US2981533A

US2981533A - Time delay apparatus

Info

Publication number: US2981533A
Application number: US723763A
Authority: US
Inventors: Wallace D Wilson; Jr Glenn W Johnson
Original assignee: Elastic Stop Nut Corp
Current assignee: Elastic Stop Nut Corp
Priority date: 1958-03-25
Filing date: 1958-03-25
Publication date: 1961-04-25
Anticipated expiration: 1978-04-25

Description

TIME DELAY APPARATUS Filed March 25, 1958 FIG.| 3% 44 a: 26 I51 Q3 /46 2 d 3 2 I 54 so I I 2g 1/ 2 IO l8 5 H "1 68 I2 M HWIIW 5 INVENTORS WALLACE D.W|LSON AT TORNEY z GLENN W. JOHNSON,JR.

Jr., Summit, N.'J., assignors to Elastic Stop Nut Cor-' poration of America, Union, N..l., a corporation of New Jersey Filed Mar. 25, 1958, Ser. No. 723,763

7 Claims. (Cl. 267-1) This invention relates to timing devices and more particularly to time delay apparatus and still more particularly to such apparatus in which air or other gas is used as the timing medium. More specifically the invention relates to such apparatus which will maintain a substantially constant time delay period throughout a wide temperature range.

Time delay apparatus is known having a wall and a flexible diaphragm cooperating to provide a timing chamber, and an orifice through the wall. In such apparatus the diaphragm is moved to cause the gas to flow through the orifice during a time delay cycle, the duration of which is a function of the rate at which the gas flows through the orifice.

For certain applications it is desirable that the duration of the time delay cycle, or the time delay period be as constant as possible between about minus 65 degrees F. and plus 180 degrees F. With respect to the time delay period at room temperature, prior apparatus of the type referred to above has been subject to a variation in the time delay period of as much as minus 30% at minus 65 degrees F. to plus 20% at plus 180 degrees F. Thus if such prior apparatus is set for a time delay period of one minute at room temperature, the time delay period may be as little as 48 seconds at minus 65 degrees F. and as much as 78 seconds at plus 180 degrees F.

The presentinvention makes it possible to maintain, Within the temperature range referred to, the time delay period well within plus or minus of the time delay period at room temperature.

It is known that the viscosity of air or other gas is a function of temperature, the gas being more viscous the higher its temperature. In prior apparatus of the type referred to, the timing gas flows through the orifice more slowly at high temperature than at low temperature, and this accounts for the substantial variation in the time delay period.

Apparatus in accordance with this invention contains simple, inexpensive means for compensating for the change in viscosity of the timing gas to maintain the rate at which timing gas flows through the orifice, and hence the time delay period as well, substantially constant throughout the temperature range.

This invention provides gas timed time delay apparatus having a wall and a flexible diaphragm cooperating to provide a timing chamber and an orifice through the wall with means providing a bias against the diaphragm during a time delay cycle for moving the diaphragm in a predetermined direction to change the volume of the timing chamber and to cause timing gas to flow through the orifice, the means including a bi-metallic element for regulating the magnitude of the bias as a function of the temperature of the gas at all operative positions of the diaphragm during the time delay cycle.

Important objects of the invention are to provide time delay apparatus possessing the above advantages.

The above and other objects and advantages will appear more clearly from the following description of a preferred Patent Patented Apr.'25, 1961 example of the invention and the accompanying drawings thereof in which:

Fig. 1 is a view on line 1-1 of Fig. 2, showing apparatus embodying the invention at the start of a time delay cycle;

Fig. 2 is a view on line 2-2 of Fig. 1;

Fig. 3 is a plan view of the bi-metallic element of the apparatus, by itself;

Fig. 4 is a view on line 44 of Fig. 3; and

Fig. 5 is a view on line 5-5 of Fig. 4.

The drawings show time delay apparatus including a timing head assembly indicated generally at 6 (Fig.1) which includes a timing head cover 8 defining an axis and having an internal configuration providing a generally concave wall 10 and having an annular flange surface 12 perpendicular to the axis.

Timing head assembly 6 also includes a base ring 14 having an annular flange surface 16 confronting flange surface 12 and a circular flexible diaphragm 18 the outer periphery of which is clamped between confronting

surfaces

12 and 16. Timing head cover 8 and base ring 14 are suitably held together as by screws (not shown).

Wall lib of timing head cover 8 and diaphragm 18 thus cooperate to provide a timing chamber 20.

Suitably secured to and depending from the center of diaphragm 18 is a spindle 22 having a pair of external axially spaced confronting shoulders 24 for engaging other mechanism such as a switch (not shown) to control and change the condition thereof as will be more fully explained hereinafter.

A timing orifice 26 is provided through Wall ltl of timing head cover 8, and timing gas, such as air or nitrogen, can flow through orifice 26 to change the volume of timing chamber 20, also as will be more fully explained hereinafter.

Wall 10 includes an internal cylindrical surface 28 intersecting flange surface 12, a plane surface 30 intersecting surface 28 and extending therefrom toward the axis of timing head cover 3 and confronting the outer portion of diaphragm 13, an internal cylindrical surface 32 intersecting surface 30 and extending therefrom in the direction away from diaphragm 18, a plane surface 34- intersecting surface 32 and extending therefrom toward the axis of timing head cover 8 and confronting a radially inner portion of diaphragm 18, an external cylindrical surface 36 intersecting surface 34 and extending therefrom toward diaphragm 18 and a plane surface 38 perpendicular to the axis of timing head cover 8 and confronting diaphragm 18 and defining the end of surface 36 remote from surface 34. As shown. the axial length of surface 36 is less than the axial length of surface 32.

Thus

surfaces

32, 34 and 36 define an annular recess or well 40 having an open end facing diaphragm 18.

Timing orifice 25 extends perpendicularly through wall 10 from a radially outer portion of surface 30.

In timing chamber 20 is an assembly comprising a coil spring 42, a spring retainer 44 and a bi-metallic temperature-compensating element 46.

Spring retainer 44 is in the form of a sleeve open at both ends and having an internal annular flange 48 at one end and an external annular flange 50 at the other end. Spring retainer 44 is coaxial with timing head cover 8 and is partly in recess 40 with internal flange 48 confronting surface 34 and external flange 50 confronting diaphragm 18.

The radially inner portion of diaphragm 18 is clamped between a coupler 52 in timing chamber 20 and a washer 56, coupler 52 being in threaded engagement with one end of spindle 22. Coupler 52 has an annular flange surface 54 confronting external flange 50 of retainer 44.

Spring 42 is located largely within retainer 44, and one end of spring 42 engages internal flange 48 of re- 3 miner-44 and the-otherend engages flange surface 54 of coupler 52. Spring 52 is under compression to tend to elongate to move diaphragm 13 away from surface 38 thus to enlarge timing chamber 20. Thus spring 42 provides a bias against diaphragm 18.

Several turns of spring 42 are in well 4%} radially between surface 36 and retainer 44.

Bi-metallic element 46 is made of a laminated sheet of two metals having different coefficients of thermal expansion and has a flat, generally rectilinear portion 58 having a central circular aperture 60 therethrough of greater diameter than the outside diameter of retainer 44 (except for external flange 50). A pair of similar arcuate legs 62 depend from and are integral with opposite ends of rectilinear portion 53. Each leg 62 is of approximately 180 degrees in arcuate extent. Similar flat portions 64 overlying and spaced from portion 58 extend toward each other from the ends of legs 62 remote from rectilinear portion 58. As shown in Fig. 4, which illustrates element 46 by itself at room temperature, portions 64 are coplanar and parallel to portion 58. The ends of portions 64 remote from legs 62 have confronting arcuate cut-out parts 67 which provide for the free passage therethrough of retainer 44 (except for flange 50).

Flat portions 64 have inner spaced ends in the form of four similar projections 66 extending away from the plane of rectilinear portion 58.

Bi-metallic element 46 is under compression in timing chamber with: rectilinear portion 58 lying flat against surface 36; projections 66 engaging that side of flange 50 which faces well 40; and retainer 44 passing through cut-out parts 67 and aperture 60.

The material of bi-rnetallic element 46 having the lower coefiicient of expansion is on the outside. Thus, with rising temperature, the distance between projections 66- and the plane of rectilinear portion 58 will tend to increase, and the distance between internal flange 48 and flange surface 54 of coupler 52 for any given axial position of coupler 52 (and the central portion of diaphragm 18) is a function of temperature. In turn the length of spring 42 and the bias against diaphragm 18 are also controlled as a function of temperature.

More specifically, for any given axial position of coupler 52, the resilient means comprising spring 42 and bi-metallic element 46 will provide a greater bias against diaphragm 18 at higher temperature than at lower temperature.

Means such as a solenoid or recycling spring (not shown) moves spindle 22, diaphragm 18 and coupler 52.

in the direction of the arrow (Fig. 1) and holds spindle 22 in that position until the delay cycle is begun (as by de-energizing the solenoid). During this movement, the volume of timing chamber 29 is reducedand air or other timing gas leaves timing chamber 20 quickly through valve means indicated generally at 68.

Also during the movement referred to spring 42 is axially compressed (shortened) to the condition shown in Fig. 1, retainer 44 is moved toward surface 34 to the position shown in Fig. l and bi-metallic element 46 is further compressed to the condition shownin Figs 1, in which projections 66 are closer to rectilinear portion 58.

Thus, with diaphragm 18 and related parts positioned as shown in Fig. 1, spring 42 exerts a bias against dia-- phragm 18 tending to expand timing chamber 20, and bi-metallic element 46, by controlling, through retainer 44, the length of spring 42, regulates this bias. If it be'assumed that Fig. l showsthe parts at room temperature, and that the temperature rises, then bi-metallic element 46 will expand from the illustrated condition, so. that projections 66 will be closer to diaphragm 18. This in turn will move retainer 44 closer to diaphragm 18 to shorten spring 42 and increase the bias thereof. If the. temperature drops below room temperature, the reverse occurs and the bias of spring 42 will be decreased.

If now the means holding spindle 22 in the position of Fig. l is released to start the time delay cycle, the.

resilient means comprising spring 42 and bi-metallic element 46 causes diaphragm 18 and related parts to move in the direction opposite that indicated by the arrow in Fig. 1, immediately closing valve means 68 to expand timing chamber 20. Also, during the time delay cycle, air or other timing gas is drawn into timing chamber 20 through orifice 26. The rate at which the gas is drawn through orifice 26 and in turn the rate of axial movement of spindle 22 are dependent upon the viscosity of the gas and the force or, bias exerted on diaphragm 18 by the resilient means comprising spring 42 and bi-metallic element 46.

As has been pointed out the timing gas is more viscous at higher temperatures than at lower temperature, that is, more force is required to cause the gas to flow through orifice 26 at the same rate at higher temperatures than at lower temperatures. Bi-metallic element 46 compensates for these changes in viscosity by providing a greater force at higher temperatures and a lesser force at lower temperatures.

Thus, with the invention, spindle 22 will travel at substantially the same rate during the time delay cycle at all operating temperatures, and therefore the time delay period will be substantially constant for all operating temperatures.

It is noted that retainer 44 is free-floating. That is,- retainer 44 is supported only by spring 42 and bi-metallic element 46 and there is a clearance between retainer 44 at one end thereof and surface 34 and between retainer 44 at the other end thereof and coupler surface 54, so that there is no interference with the temperature-compensating action of bi-metallic element 46, either at the lower or upper end of the temperature range. Exceptions might be: at the lower temperature limit and at the start of the time delay cycle, retainer 44 might just touch surface 34; and at the upper temperature limit at the start of the time delay cycle retainer 44 might just touch surface 54.

Projections 66 perform the function of assuring that the same parts of element 46 engage flange 50 at all times. Thus the lever arms of element 46 are substantially constant in length and more uniform time delay periods assured.

It has been pointed out that the invention provides means providing a bias against the diaphragm for mov ing the latter to change the volume of the timing chamber and to cause gas to flow through the orifice. In the illustrated example the means referred to comprises a spring and a separate bi-metallie element, but the spring and the bi-metallic element could be combined in a single part. In any event the bi-metallic element provides at least indirectly at least a part of the bias against the diaphragm.

Preferably the bi-metallic element is under compression during all parts of the time delay cycle at all operative temperatures. If this were not so, the bi-metallic element would not under some circumstances provide any part of the bias against the diaphragm and there would be no compensation for changes in temperature.

The invention is well adapted to the attainment of the stated objects and advantages and others.

Various changes in the details of the illustrated examplecan be made without departing from the invention. Therefore those details are not to be taken as limitations upon the invention except insofar as the details may be included in the appended claims.

What is claimed is:

1. In gas timed time delay apparatus having a wall and a flexible diaphragm cooperating to provide a timing.

chamber and an orifice through said wall: means providing a bias against said diaphragm during a time delay cycle for moving said diaphragm in a predetermined direction to change the volume of said' timing chamber and to cause gas to fiow through said orifice, said means including a bi-metallic element for regulating the magnitude of said bias as a function of the temperature of said gas at all* operative positions of said diaphragm during said time delay cycle.

2. In gas timed time delay apparatus having a wall and a flexible diaphragm cooperating to provide a timing chamber and an orifice through said wall: resilient means providing a bias against said diaphragm during a time delay cycle for moving said diaphragm in a predetermined direction to change the. volume of said timing chamber and to cause gas to flow through said orifice, said means including a resilient bi-metallic element for regulating the magnitude of said bias as a function of the temperature of said gas at all operative positions of said diaphragm during said time delay cycle, said bi-metallic element providing at least indirectly at least a part of said bias.

3. In gas timed time delay apparatus having a wall and a flexible diaphragm cooperating to provide a timing chamber and an orifice through said wall: means providing a bias against said diaphragm during a time delay cycle for moving said diaphragm in a predetermined direction to change the volume of said timing chamber and to cause gas to flow through said orifice, said means including a spring and a bi-metallic element for regulating the magnitude of said bias as a function of the temperature of said gas at all operative positions of said diaphragm during said delay cycle.

4. In gas timed time delay apparatus having a wall and a flexible diaphragm cooperating to provide a timing chamber and an orifice through said wall: means providing a bias against said diaphragm during a time delay' cycle for moving said diaphragm in a predetermined direction to. change the volume of said timing chamber and to cause gas to flow through said orifice,

said means including a coil spring and a resilient bimetallic element for regulating the magnitude of said bias as a function of the temperature of said gas at all operative positions of said diaphragm during said delay cycle.

5. In gas timed time delay apparatus having a wall and a flexible diaphragm cooperating to provide a timing chamber and an orifice through said wall: means for moving said diaphragm in a predetermined direction during a time delay cycle to change the volume of said timing chamber and to cause gas to flow through said orifice, said means including a coil spring providing a positive bias against said diaphragm in said direction and a resilient bi-metallic element associated with said spring for regulating the magnitude of said bias as a l 6 function of the temperature of said gas at all operative positions of said diaphragm during said delay cycle, so that said bias is greater at higher temperature than at lower temperature.

6. In gas timed time delay apparatus having a wall and a flexible diaphragm cooperating to provide a timing chamber and an orifice through said wall: means for moving said diaphragm in a predetermined direction during a time delay cycle to change the volume of said timing chamber and to cause gas to flow through said orifice, said means including a compression coil spring having an end facing said diaphragm and providing a positive bias against said diaphragm in said direction and a resilient bi-metallic element havinga fixed portion and a movable portion controlling the position of the other end of said spring and the length of said spring, Whereby said bi-metallic element regulates the magnitude of said bias as a function of the temperature of said gas at all operative positions of said diaphragm during said delay cycle, so that said bias is greater at high temperature than at lower temperature. I

7. In gas timed time delay apparatus having a wall and a flexible diaphragm cooperating to provide a timing chamber and an orifice through said Wall: means for moving said diaphragm in a predetermined direction during a time delay cycle to change the volume of said timing chamber and to cause gas to flow through said orifice, said means including a compression coil spring having an end facing said diaphragm and providing a positive bias against said diaphragm in said direction, a free-floating sleeve-like spring retainer having an internal flange at one end and an external flange at the other end, the end of said spring remote from said diaphragm being within said retainer and bearing against said internal flange, and a bi-metallic element having a fixed portion and a movable portion engaging that side of said external flange remote from said diaphragm and providing a pressure against said external flange in said direction to control the position of said internal flange and the length of said spring, whereby said bi-metallic element regulates the magnitude of said bias against'said diaphragm in said direction as a function of the temperature of said gas at all operative positions of said diaphragm during said delay cycle, so that said bias is greater at higher temperature than at lower temperature.

References Cited in the file of this patent UNITED STATES PATENTS