US2412725A

US2412725A - Fluid pressure control mechanism

Info

Publication number: US2412725A
Application number: US572275A
Authority: US
Inventors: Ellery R Fitch
Original assignee: Bendix Westinghouse Automotive Air Brake Co
Current assignee: Bendix Westinghouse Automotive Air Brake Co
Priority date: 1945-01-11
Filing date: 1945-01-11
Publication date: 1946-12-17
Anticipated expiration: 1963-12-17

Description

De@ 17,1946. E. R. FITCH FLUID PRESSURE CONTROL MECHANISM Filed Jan. ll, 1945 INVENTOR. EzlefyRf/L.

ATTORNEYS Patented 11, 19f4c l '2,412,725 raum rasssmm coNTaoL Macnamsm Elyris, ohio. asignar to sensi tive Air Brake Company, a corporation of Delaware l ElleryILFltch,

Westinghouse Antonio Elyria, Ohio,

Appliesuon .Imm-y 11, 194s, serial No. 512.215

. s claims. (ci. rs1-15a) This invention relates to iluid pressure control mechanism; and more particularly to mechanism of the above type for controlling the operation of a compressor or pump in accordance with variations of pressure in the reservoir supplied by. the compressor.

Numerous constructions .have been previously proposed for accomplishing this type of control, but many of these constructions' have involved -the use of intricate and delicate parts which prevented economical manufacture of a device of this type. and it is accordingly an object of the present invention t 'provide mechanism of the above type so consti uted as to eliminate the use of delicate operating parts and to facilitate economical manufacture.

' Another object of the invention is to provide a control mechanism or compressor governor of the above type, so constituted as to insure positive operation/in accordance with variations of pressure'in the compressorfreservoir in order to insure a uniform and" reliable control of the .operation oflthe'compressor. Y t

Yet another object of the invention is to provide a governor of the above type. sov constituted Y 2 Referring more particularly to Fig. l of the drawing. a iluid pressure supply system is shown diagrammatically, and includes in general a compresser l, a storage reservoir 5 adapted to be supplied A with fluid pressure from the compressor through a conduit 6, a governor mechanism-1, v to be more fully described hereinafter, and an unloading mechanism 8 of conventional type mounted on the compressor. an outlet'conduit 9 is connected from the governor to theunloader 8 on the compressor, and pre e is supplied to the governor from the reservoir through a conduit I0, the governor in turn being provided with an exhaust conduit il. v I'he unloader 8 on the compressor is of the fluid pressure operated type, and it will be understood by those skilled in the art, lthat. when fluid pressure is supplied to the unloader from the goveras to permit ready adjustment of the device whereby the latter will become effective at a desired pressure to unload thecompressor.

Still another vobject of the invention isto provide, in a governor of the above type. means for insuring positive loading and unloading action of the governor in accordance with variations of the pressure in the reservoir.

A further object of the invention is to provide magnetic means for insuring positive operation of the valves to load andunloa'd the compressor.

These and other novel features and objects of the invention will appear more fully hereinafter from the following detailed description when considered in connection with the accompanying drawing wherein one embodiment of the invention is illustrated. It is to be expressly understood, however, that the drawing is employed for purposes of illustration only, and is not designed as a deilnition ofthe limits lof the invention, reference being had for this purpose to the appended claims.

In the drawing: Fig. 1 is a diagrammatic view, partially in section, of a uid pressure supply system having a compressor or pump controlled by a governor of' the above type, and

Fig. 2 is an enlarged sectional view showing a modiilcation of a portion of the mechanism shown in Fis. l.

' phragm Il is clamped in the casing as shown,

- nor, the unloader will be operated to render the compressor ineffective to Supply fluid pressure to the reservoir 5 through the conduit t. With the parts o f the governor 1 in the position shown, communication is permitted between outlet conduit 9 and the exhaust conduit II, and is prevented between the supply conduit Il and the outlet conduit 9, an increase in pressure in the' reservoir` 5 above a predetermined value serving to operate the governor mechanism to prevent communication between conduits 9 and il and to establish communication between conduits lo and 9, whereupon the unloader 8 is operated to unload the compressor.

Referring more particularly to the sectional Y view of the governor mechanism 1, a casing l2, is

provided with an inlet chamber Il, an outlet chamber Il, an exhaust chamber I5, and a supply chamber It. A pressure responsiveV diaand a chamber i8 formed in the casing directly below the diaphragm is connected by a bore I9 with the supply chamber I9, the result being that the lower surface of the diaphragm is subjected at all times to the pressure inthe supply cham' ber, and consequently to the pressure in the storage reservoir. A diaphragm stem 20 is connected to the diaphragm by means of a clamping washer 2| and a clamping nut 22 threadedly received on the upper end of the stem. and the diaphragm is normally biased in a. downward direction with a predetermined force by means of a spring 23 interposed between the casing and a washer 24 ad- Justably positioned on the lower end of the stem by means of an adjusting nut 25 threadedly reinlet chamber I3 is connected with the supply t chamber I6 by means of a passage 33 formed in the casing, a port 3,4 being provided in the right t side of the diaphragm I1 in order to permit the flow of fluid pressure through the passage from the supply chamber to the inlet chamber. A valve operating element 35 is slidably mounted in a bore 3S formed in the casing, a sealing element 31, mounted in the bore in engagement with the valve operating elementserving to prevent leakage from the outlet chamber to the exhaust chamber I5. The valve operating element is provided with a'central bore 33, and a lower end of this bore is in` communication with the exhaustchamber I5, as will be more fully pointed out hereinafter. Thus, with the valve operating ele'- ment in th'position shown, the outlet chamber I4 is connected with atmosphere through thebore 38, the exhaust-chamber I5 and a passage 39 to which the exhaust conduit II is connected, while on upward movement of the valve operating element, the exhaust valve 32 is iirst engaged to prevent communication between the outlet chamber and atmosphere, and the inlet valve is subsequently moved to open position to permit iluid pressure to be supplied to the unloader 3 from the reservoir 3 through conduit III, supply chamber I3, bore I3, chamber I3, diaphragm port 34, passage 33, inlet port 21, outlet chamber I4, passages 40 and 4I formed in the casing, and conduit 9;

In mechanismsof the above type, itis essential that the inletfandexhaust'valveswhich serve to control the supply of fluid pressure to the unloader 'of the compressor, operate instantaneously in order to prevent partial unloading andv loading of the compressor, and to this end, novel means are provided for insuring instantaneous movement of the valve operating element from oneposition to another in response to variations of pressure in the reservoir 5. The valve operating element is accordingly provided with an artion. Consequently, the application of a predetermined force to move the valve operating element downward from the above position will again result in rapid movement of the element lin that direction and instantaneous closing of the inlet valve and opening of the exhaust valve.

In order that the valve operating element may be operated in accordance with variations of pressure in the reservoir 5, an operative connection is provided between the diaphragm I1 and the lower end of the element. A flange 45 is\ formed on the lower end of the element, and with the' parts in the position shown, the upper surface of the ange is adapted to be engaged by a pair of lips 46 formed on a pair o! upwardly extending members 41 formed integrally with a` diaphragm clamping nut 22, vthis contact being normally maintained by means of a spring 43 interposed between the upper surface of the nut and the lower end of the valve operating element', Thus the spring forms a resilient operating connection between the diaphr gm and element, and by properly dimensioni g the parts, the spring may be initially'preloaded to exert any desired force in the position shown. The g upper end of the plunger 20 is provided with an extension 49 which .is adapted to directly engage the valve operating element when suilicient force has been applied to the plunger to overcome the force exertedfby the spring 43. The tension of' the spring 48 is preferably so chosen that on upward movement of the plunger 20, the extension mature portion 42 formed of magnetic material such as iron, and adapted in the position shown, to engage permanent magnets 43 rigidlyv positioned in an adjustable member 43a threadedly received in the casingas shown. Thus the valve operating element is maintained in the position shownwith a predetermined force, and since the characteristics of a permanent magnet and armature are such that the attracting force decreases with extreme rapidity as the armature moves away from the magnet, it will be understood that when a force is applied to the valve 'operating elementsuilicient to move it away from the magnets, the element will move rapidly upwardly to close the exhaust valve and open the inlet valve. In order to insure a 'similar rapid `movement of vthe valve operating element in the reverse direction to-close the inlet valve and open the exhaust valve, similar permanent magnets 44 are rigidly attached to the casing and are adapted to be contacted by the upper surfaces of the armature when the latter and the valve operating element are in inlet valve opening posi- 49 is permitted to engage the lower end oi the valve operating element before sufficient force is being exerted on the latter by thev spring 43 to cause the armature to move lupward from the magnets 43. Thus when suflicient force is exerted upwardly on the valve operating element by the spring 48 and the extension 49 to cause'the armature to move upward away from the magnets 43, the spring 43 will tend to rapidlyy move the valve operating element and the armature 42 upward into engagement with the permanent magnets 44.

When the compressor is started initially, the pressure in the reservoirv 5 and in the `chamber I6 ofthe governor, will gradually increase to a point where the pressure acting upward on the diaphragm is sufficient to vovercome the tension of the spring 23.l whereupon the diaphragm will move upward to collapse the spring 43, and the diaphragm will exert force directly on the valve operating element through the` extension 49. When this force exceeds the. force exerted by the lmagnets 43 on the armature'42, the valve operating element will be moved upward by the action of the diaphragm, through the projection 49 and the spring 43, and the valve Voperating element will immediately act to close the exhaust valve and open the inlet valve to supply fluid pressure from the reservoir to the unloader 3 through the passages heretofore described. At the same time,'the armature will engagev themagnets 44 and will be retained in engagement therewith until suilicient force is exerted on the valve operating element in a downward vdirection to move the armature away from the magnets 44. The reservoir is provided with an outlet conduit 50, which may be connected with any suitable iluid pressure actuator, not shown, together 'with ldescribed in thenreceding paragraph, no further iluid pressure will 'S supplied to the reservoir, and the pressure in the latter will decrease, either due to leakage or due to the opening oi.' the valve to supply iluid pressure to the actuator. 'I'hel pressure in the chamber I5 and in the diaphragm chamber I3 will decrease correspondingly, and a Apoint will eventually be reached such thatthe force exerted downwardly on the plunger by mit the return oi the diaphragm to the position shown under the action ot the spring 23 will also be governed by the spacing of the magnets 43 and 44. andby adjusting the spacing of the magnets in conjunction with an adjustment of the tension of the spring 23, the pressure at which the governor operates to unload the compressor,

. as well as the pressure at which it operates to the spring 23 and the air pressure acting on the upper end of the valve operating element willi exceed the force exerted upwardly on the diaphragm by iiuid pressure and the force exerted by the magnets 44 on Athe amature 42, whereupon the valve operating element will move downc ward to permit closing of the inlet valve by the action oi' the spring 28 and opening of the exhaust valve to permit the exhaust of iluid presagain'load the compressor, may be aozljusted to any desired value within the limits of any particular design.

It is` also considered desirable in some cases in connection with the resilient lost motion connecsure vfrom the unloader 8 to atmosphere through to overcome the attraction of the magnets 44,-

and since the force of this attraction substantially disappears as soon as the armature leaves the magnets, it will be understood that the parts 4 may be so designed that this force -is also sumcient to move the valve operating element and armature downward sufficiently to cause the latter to reengage the magnets 43. When this action occurs, the parts are again substantially ina position shown in the drawing, and will. remain in this position until the pressure in the reservoir increases sufllciently to cause the governor ...i

to again operate to supply fluid pressure to the tion between the diaphragm and valve operating element. to provide a construction so constituted as to render the collapsible spring effective in both directions of operation, and to this end, a modiied construction of the operative connecting means between the diaphragmand valve operating element is illustrated in Fig. 2 of .the

drawing. In this modication, the valve operating element 35 is provided with a shoulder .53,

unloader mechanism to unload the compressor.

As her'etoiorestated, the tension of the spring 23 may be adjustably controlled by means of the adjusting nut 25, and this adjustment may be made at will. by the` operator on removal oi' a cover 52 normally maintained in sealing engagement with a lower end of the casing by means not shown, in order to normally prevent leakage ofA iluid pressure from the chamber I'5.

There has thus been provided in the mechanism shown in Fig. 1, means for moving the valve operating element 35 yfrom one position to another with a positive snap action in order to operate the inlet and exhaust valves 28 and 32 to control the supply of fluid pressure to the unloading mechanism 3. This snap action is further enhanced if desired by means of a lost motion connection between the diaphragm and the valve operating element, this lost motion including the collapsible spring 48 and the lips 45 formed on the members 4'l and serving to engage the ange on the valve operating element. The'pressure at which the mechanism becomes effective to supply uid pressure from the reservoir to the unloader mechanism can be controlled by adjustment of the tension of the spring 23, and the pressure range of the governor can be controlled by adjustment of the magnet carryingmember 48a. l The distance between the magnets 43 and 44 determines the travel of the valve operating element-as well as the travel of the diaphragm and the plunger 20, and it will be understood that the force exerted by the spring 23 to move the valve operating element downward to the position shown will increase with an increase in travel of the valve operating element, and will decrease when the travel is correspondingly decreased. Thus the change in pressure necessary in the diaphragm chamber I8 to perand a nut 54 threadedly received on its lower l end. A pair of washers 55 and 55 are slidably mounted on the valve operating member between the shoulder 53 and the nut 54,' and are normally maintained in the positions shown by a preloaded spring 43 interposed between the washers. The extension 48 is omitted from the upper endl of the plunger 20, and a sleeve 51 is threadedly received by the nut as shown'. The upperend of the sleeve is provided with a bore 58 adapted to s'lidably receive the ilange 53, and a shoulder 58 is adapted to'engage the upper surface of the washer 55, the

lower surface of the washer 55 being normally engaged by an annular portion 60 formed in the nut 22. The shoulder 58 and the annular portion V are so spaced as to. engage `the washers and 55 without further compressing the spring4 48 with the parts in normal position. Onupward movement of the diaphragm and the nut 22 as the pressure below the diaphragm increases, the spring 48 is compressed in the manner described in connection with the construction shown in Fig. 1 and serves to assist lin insuring engagement of the armature with the upper magnets 44. When the diaphragm and plunger are moved in the opposite direction under the action of the spring 23, and in response to a reduction in pressure in the reservoir, the sleeve 51 moves downward with the diaphragm and plunger, andthe shoulder 58 picks up the washer 55, and moves it downward to compress the spring 48 fwhile the armature is still in engagement with magnets 44. When the spring 48 has been compressed a predetermined degree, a shoulder 6i formed on the upper end of the sleeve 51 engages the uppersurface of the shoulder 53 on the valve operating element and exerts a force directly on the element to move the armature away from the magnets 44. Assoon as the armature lleaves these magnets, the magnetic force decreases rapidly, and the spring 48 is operative to move the valve operating element downward in order to permit' engagement of the armature with magnets 43.

While this lost motion connectonas well as that illustrated and described in Fig. 1,'may be advantageous in certain types of "construction, it will be understood that the lost motion and there-- silient connection may be eliminated in some cases without interfering materially with satisfactory operation of the governor mechanism.

of the sleeve 5l which insures communication be- 7 tween the passage 38 in the valve operating element and the exhaust chamber 45. Although one embodiment of the invention and a, modification of a portion of the mechanism have been described andillustrated herein, it will be expressly understood that various changes and substitutions may be made therein without departing from the spirit of the invention, as willbe'well understood by those skilled in the art.

, Reference will, therefore, be had to the appended claims for a deiinltion of the limits of the invention. f What is claimed is:

1l. A'pressure responsive governor including a casing having an inlet chamber, an outlet chambenl an exhaust port, inlet and exhaust valves for, normally preventing communication between the,` inlet and outlet chambers and for normally permitting communication' between said outlet .i1-chamber and exhaust port, a valve operatingl ielement movable in one direction to close the exhaust valve and open the inlet valve, means responsive to the pressure in the inlet chamber for moving the element in said one direction.

resilient means vfor moving the element in the other direction, means including magnets for opposing movement of the element in either direction, and means for varying the tension of said resilient means together with means to vary the y effect of said magnets to adjust the range of the governor.'

2. A pressure responsive governor including a casing having an inlet chamber, an outlet chamber, an exhaust port, inlet and exhaust valves for normally preventing communication between the inlet and outlet chambers and for normally permitting communication between said outlet chamber and exhaust port, a valve operating element operable in one position to open the 'exhaust valve and operablev on movement to another position to close the exhaust valve and open the inlet valve,l a magnet for opposing movement of the element from ysaidone posi- Ition with a predetermined force, a magnet for opposing movement oi' the element from said another position with a predetermined force, means responsive to the pressure in the inlet chamber for moving the element from said one position to said another position, resilient means -for moving the element fromsaid another positiontosald one position, and means for varying the tension of said resilient means together with means tovary the effect of said magnets to adjust'the range of the governor. y

v3. A pressure responsive governor including a casing having an inlet chamber, an outlet chamberan exhaust port, inlet and exhaust valves 'for` normally preventing communication between the inlet and outlet chambers and for normally permitting communication between said outlet chamber and exhaust port, a valve operating element operable in one position to open the exhaust valve and operable on movement to another'position to close the exhaust valve and eiiect oiA said magnets to adjust the range of the governor.

4. A pressure responsive governor including a casing having an inlet chamber, an outlet chamber, an exhaust port, inlet and exhaust valves for normally preventing communication between the inlet and outlet chambers and for normally permitting communication between said outlet chamber and exhaust port. a valve operating element movable in one direction to close said exhaust valve and open said inlet valve, means including a magnet for opposing movement of the element in said one direction with a predetermined force, means responsive to the pressure in said inlet chamber for moving the element in said one direction, and preloaded resilient means'for connecting said element and pressure responsive means and permitting'relative movement of said pressure responsive means and element prior to movement of the element in said one direction by the operation of said pressure responsive means.

5. A pressure responsive governor including a casing having an inlet chamber, an outlet chamber, an exhaust port, inlet and exhaust valves for 'normally `preventing communication between th`e inlet and outlet chambers and for normally permitting communication between said outlet chamber and exhaust port, a valve operating element operable in one position to open the exhaust valve and operable on movement to another position to closethe exhaust valve and open the inlet valve, means including a permanent magnet for opposing movement of said element from either one of said positions to the other of said positions with a predetermined forcefresilient means `for 'moving said element cluding a preloaded spring for connecting said member and element and for normally opposing Irelative movementl of said member andelement with a predetermined force, said last named predetermined force being less than said first named predetermined force. i

6. A pressure responsive governor including av casing having an inlet chamber, an outlet chamber, an exhaust port, inlet and exhaust valves for normally preventing communication between the inlet and outlet chambers and for normally permitting communication between saidoutlet/chamber and exhaust port, a valve operating element operable in one position to open the exhaust valve and operable on movement to another position to close said exhaust valve and open said inlet valve, permanent magnet means-for opposing movement of said element from either one of said positions with a predetermined i'orce, a member responsive to the pressure in the inlet chamber for moving the element from said one position to said another position, and connecting means for said element and member for permitting vlimited relative movement therebetween in either direction including a-preloaded spring for' opposing said relative movements with a force less than said predetermined force.

7. A pressure responsive governor including a casing having an inlet chamber, an outlet cham- 'ber, an exhaust port, inlet and `exhaust valves outlet chambers and for normally permitting communication between said outlet chamber and exhaust port,v a valve operating element movable in one direction to close the'exhaust valve and open the inlet valve, means responsive to the pressure in the inlet chamber for moving the element in said one direction, resilient means for moving the element in the other direction, means including spaced magnets for opposing and limiting the movement of said element in either of said directions, and means for adjusting the tension of said resiilent means and the spacing of said magnets, whereby the valves are operable to respectively connect the inlet and outlet chambers and to connect the outlet chamber and exhaust port at different predetermined pressures in the inlet chamber.

8. A pressure responsive governor including a casing having an inlet chamber, an outlet chamber, an exhaust port, inlet and exhaust valves for normally preventing communication between the inlet and outlet chambers and for normally permitting communication between said outlet chamber and exhaust port, a valve operating element operablevin one position to close the exhaust valve and open the inlet valve'and oper 10 able in another position to open the exhaust valve and permit closing of the inlet valve, Van armature connected with the valve operating element, a permanent magnet carried. by the casing adapted to engage and maintain the armature and element in said one position with a predetermined force. a permanent magnet spaced from the first named magnet adapted to engage and maintain the armature and element in said another position with a predetermined force, means responsive to the pressure in the inlet chamber for moving the element from said an other position to said one, position, resilient means for moving said element from said one position to said-another position when the pressure is reduced in the inlet chamber. and means for varying the spacing of said magnets and correspondingly varying the travel of said element, whereby the degree of variation in force exerted by said resilient means on the element on movement of the latter between said positions is varied and the degree of pressure reduction required in the inlet chamber to permit -movement of the element to said another position correspondingly varied.

ELLERY R. FTI'CH.