US1664849A - Governor - Google Patents

Description

April s, 1928.

O. N. BRYANT GOVERNOR Filed May 22, 1925 3 Sheets-Sheet 1 ATTORNEY April 3, 1928. 1,664,849 O. N. BRYANT GOVERNOR v Filed y 2, 1925 5 Shegts-Shi a V I 0.N.Br ant WITNESSES: lNVEN OR ATTORNEY Patented Apr. 3, 1928.

UNITED STATES 1,664,849 PATENT OFFICE.-

OZRO N. BRYANT, 0F MOORE, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELEC- TRIO & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

GOVERNOR.

' Application filed May 22, 1925. Serial No. 32,039.

My invention relates to governing apparatus, more specifically to governing apparatus operated by variable fluid pressure, and has for its object the provision of apparatus of the character designated which shall be simple of design, positive in action and which shall effect close regulation of the machine governed.

Apparatus embodying features of my in vention is illustrated in the accompanying drawings in which Fig. l is a view in elevation showing an elastic-fluid turbine having my improved governing apparatus applied thereto; Fig. 2 is avertical sectional view of the governing apparatus shown in Fig. 1; and Fig.3 is a view similar to Fig. 2 showing a modified form of my improved governing apparatus.

Variable fluid pressure operated governing apparatus, as known to me, has heretofore embodied a means of developing fluid pressure varying as a functionof the speed of the machine governed and a spring weighted element acted upon by the variable fluid pressure for effectinggoverning movements. In the design of such apparatus, difficulties have been encountered in providing a governor sufficiently sensitive to slight variations in fluid pressure and, at the same time, effecting governing movements of sufficient amplitude. This is due to the fact that a spring capable of withstanding the initial load required and capable of defiecting a sufiicient amount per unit of variation in governing pressure is of impractically great length. Various methods have been proposed for effecting a follow up motion of the spring employed in such apparatus and so reduce its length. While such apparatus has been found very efficient in operation, I have found that it may be greatly simplified and at the same time lose none of its efficiency.

In accordance with my invention, I provide a variable fluid pressure operated governor embodying a differential piston for effecting governing movements in response to differences in pressure on its sides of greater and lesser area, respectively, and provide a pressure operated relief valve for determining the pressure acting against the side of greater area. I

Referring now to the drawings for a better understandin of my invention, I show in l at 1.9 an elastic fluid turbine hav ng an admission valve 11 controlled by my improved governing apparatus at 1,2

centrifugal pump 13', driven directly by the turbine 10, develops fluid pressure varying as a function of the speed of the turbine and delivers the same through a conduit 14 to the governing apparatus 12. At 16 I.

show a fluid reservoir for supplying the pump 13'.

Referring v11.0w to Fig. 2 the governing apparatus, a 12 comprises a housing 2 whichdefines an operating cylinder17 having located therein a differential piston 18. The differential piston 18 has a face of lesser area 19 and a face of greater area 21. Variable fluid pressure is admitted through the conduit 14 to the side of lesser area 19 and is 'by-passed to the side of greater area 21,, as by an orifice 22, passingthrough said piston. The area of the upper side 19 of the piston 18 is diminished relativeto the lower side by a relatively large stem portion 23 extending through a cover 24 of the cylinder 17 and making therewith substantially a fluid-tight fit. Connected to the under side 21 of the piston 18 is a smaller stem 26 ex-- tending through a lower cover27 of the cylinder 17 and connected at its-lower end to .the admission valve 11, said stem also making an approximately fluid-tight fit with its associated cover. It will be plain from the drawing that with equal pressures on both sides of the piston 18 it will move upwardly due to the pressure acting against the greater area 21. By reducing the pressure acting against the greater area 21 sufficiently, however, the piston 18 may be caused to move downwardly. In order to accomplish this result I provide a relief valve 29 carried by a stem 31 and embodying a piston member '32 disposed within a suitably machined cylinder 33 within the body of the piston 18. Fluid pressure venteringthe upper part of the cylinder 17 passes through an orifice 34 in the stem 23 leading to the cylinder 33 above the piston member 32, so that fluid pressure developed by the pump 13 is acting at all times on said piston member tending to force the relief valve 29 downwardly in an opening direction. The relief valve '29 is also made to move toward a closing position against the fluid pressure existent beneath the piston 18 and actin against the face '21 thereof.

from eneath the piston 18 passes through a passage 36 to the upper side of the relief valve and passing said relief valve 29 drains through a passage 37 in the stem 26 and from thence through a conduit 38 back to thereservoir 16.. The rate of flow by the relief valve 29 varies in accordance with its opening, that is, the wider the opening, the greater the flow. A passage 41 leads from beneath the piston member 32 to a passage 42 which leads from the upper end of the stem 23 to the passage 37 and permits fluid leaking past the stem 23 and fluid leaking past the piston member 32 to drain into the passage 37 and thence back to the fluid reserv01r.

In order to vary the action of the relief valve 29 in accordance with the position of the operating piston 18, I provide a spring 43 secured at one end to the stem 81 of the relief valve and atthe other end to an anchor 44 carried by a suitably threaded stem 46 passing outwardly through the upper cover of the housing 20. The initial tension of the spring 43 may be varied by raising or lowering the anchor 44. This variation in the initial tension may be acomplished either manually, as by hand wheel 47, or mechanically as by a gear 48. in Fig. 1 I show the gear-48 as meshing with a worm 49 driven by a reversible motor 51.

In operation, fluid pressure admitted to the upper end of the cylinder 17 acts against the side 19 of lesser area of the differential piston, tending to force it downwardly. At the same timefluid is by-passed through the passage 22 to the side of greater area 21, from thence past the relief valve 29 to the passage 37 and from thence to the exhaust. Assuming that the area of the side 21 is twice the area of the side 19, it the pressure beneath the piston is one-half the pressure above the piston 18, it will remain stationary. Upon an increase in speed of the turbine 10, and an increase in fluid pressure developed by the pump 13, fluid pressure acting against the piston member 32 and the pressure acting against the upper side of the valve 29 forces the valve downwardly opening it wider and causing a greater flow of fluid from beneath the piston 18. This action further relieves pressure from beneath the piston 18 until it is less than half the pressure above it and it is forced downwardly. The stem 26 is connected to the admission valve 11 so that a downward move- :ment of the pistoneitects a closing movement of the admission valve 11, thus throt- .tling the supply of motive fluid to the tur- 'bine 10.

against the greater area 21 of the piston 18 increases sufficiently to balance the force exerted by the higher pressure acting against the smaller area 19, a state of equilibrium is established and no further movement takes place until there is a change in governing fluid pressure.

Upon a decrease in speed and a consequent decrease in governing fluid pressure the spring 43 further biases the relief valve 29 toward a closed position, further throttling the flow oi fluid thereby and the pressure beneath the piston 18 becomes higher relative to the pressure acting against the lesserarea 19. As soon as the pressure beneath the piston is more than half the pressure above it, the piston moves upwardly, effecting an opening movement of the admission valve.

11. This upward movement continues until the spring load on the valve 29 is reduced under pressure is constantly flowing. The

outlet to the conduit is defined by the valve 29 which permits a building up or a decrease in pressure on the side of greater area of the differential )iston, causing it to move to wards or away 'rom the higher pressure acting on its side of lesser area.

In Fig. 8' I show a modification of my invention adapted for higher initial pressure than the form illustrated in Figs'l and 2 and also adapted to exert a greater governing force. In this modification I show a housing 52 which defines an operating cylinder having disposed therein a differential piston 54. The differential piston 54 has an upper stem portion 56 which forms a fluidtight fit with the upper cover 57 of the operating cylinder 53. The stem 56 defines the side of lesser area of the difl'erential piston 54. The lower stem 58 ot the piston 54 is adapted to be connected as in the previously described modification to the admission valve 11 ot the turbine.

The u 3 er end of the housin 52 defines a pressure chamber 59 into which the variable fluid pressure is admitted through a conduit 61 and acts against the upper stem portion 56 of the diii'erential piston. Fluid flowing past the differential piston 54 passes to the drain byway of a conduit 62 located in the upper end of the cylinder 53. The difli'erential piston 54 is made hollow and has disposed in the hollow thereof a relief valve 63 for controlling the flow of fluid from the side of lesser area of the piston 54 to the lower side thereof or side of greater area a; sutflciently to permit fluid under pressure to and from the side of greater area to the. ex

nected to the lower side of the relief valve 63 is a stem'67 carried by a diaphragm 68, said diaphragm member functioning to hold the valve in a central position with respect to the hollow portion of the stem 56, and is sutliciently flexible to permit movements of the valve away from, and toward,its seat. The diaphragm 68'should be provided with holes 707O to prevent the accumulation of fluid beneath it. v

The piston portion 64 of the valve 63 has a small amount of clearance with respect to the hollow of the stem portion 56 so as to permit a restricted flow of fluid thereby. Fluid flowing past the piston portion 64, passes through a series of ports 7171 in the piston 54 to the under side thereof where it acts to counteract the greater fluid pressure acting against the stem portion 56. Fluid flowing past the relief valve 63 is free to pass through a series of port-s 72-72 provided in the piston 54 to the upper side thereof and thence outthrough the conduit 62 to the exhaust.

Inasmuch a-s the apparatus made in accordance with this modification of my invention is designed to accommodate higher initial pressures than that illustrated in Figs.

1v and 2, it is necessary to provide heavier 7 spring means for counteracting the pressure acting against the relief valve 63 as well as it is necessary to provide a larger valve 63 in order to .accommodate a greater rate of flow thereby. To this end I provide a relatively heavy spring 73 whichis carried by the piston 54 and is in compression between an abutment 74 bearing against the stem 67 of the valve 63 and the lower part of the piston 54 which is made hollow to accommodate the spring 73. The spring 73'need deflect only a very small amount in order .to furnish the valve opening required of the valve 63 and it, therefore, can be made to withstand a substantial initial load. A relatively small spring 76 is secured to the upper end of the valve 63 and is carried byan adjustable anchor 77 depending from the housing 52 as described for they first modification. The function of the spring 7 6 .is to vary the back pressure imposed upon the side of greater area of the piston 54 in accordance with the position of said piston and may be of any desired scale, it being understood that the greater the scale, the wider the governing movement effected per unit of change in governing fluid pressure.

The operation of apparatus made in accordance with this modification will be apparent. .Fluid pressure entering the pressure chamber 59 by the conduit 61 acts against the upper stem portion 56 of the piston 54 tending to force it in a downward direction. At the same time it acts against the piston portion 64 ofthe valve 63 tending to force it downwardly and the valve 63 in an opening direct-ion. Fluid flowing .past the piston portion 64 acts against the side of greater area of the piston 53 and tends to balance the force exerted by the greater pressure acting againstthe stem portion 56. Assuming that the lower side of the piston 54 is twice the area of the stem 56, if the pressure on the lower side is half the pressure acting againstthe stem portion 56, the piston 54 will be in. a state of equilibrium and will remain stationary. Under such conditions the valve 63 is open sufliciently and the springs 73 and 76 are exerting a suflicient force that the flow past the valve 63 is such that the pressure beneath the pi-ston 54 is half the initial pressure.

Should there now be an increase in governing fluid pressure, the force acting against the stem portion 56 and against the piston portion 64 of the valve 63 is increased and the valve 63 is opened slightly wider than, before, permitting an increased flow of fluid thereby and to the exhaust. Increasing the fluid flow-past the valve 63 efl'ects a decrease in pressure acting againstthe lower side of the'piston 54 and the greater relative pressure acting against the stem 56 forces the piston downwardly and the admission valve 11 in a closing direction. The piston 54 continues to movedownwardly until the spring 76, being elongated by the downward movement of the piston 5.4, increases the upward force acting against the valve 63 causing it to limit the flow of fluid thereby and to impose a greater pressure on the fluid on the under side of the piston 54. As soon as the pressure on the underside of the piston 54 is one-half the pressure acting against the stem portion 56, a state of. equilibrium is established and no further movement of the piston occurs until there is a change in governing fluid pressure.

Upon a decrease in governing fluid pressure, pressure acting against the upper stem portion 56 and the piston portion 64 of the valve 63 being decreased, the valve .63 ,is biased towards a closing position and the rate of flow of fluid thereby is decreased causing a building up of pressure beneath the piston 54. When the pressure beneath the piston 54 is more than half the pressure acting against the stem portion 56, the piston moves upwardly. As this upward movement continues, the load on the spring 76 is decreased permitting a wider opening of the valve 63 and a more rapid flow of fluid thereby. Increasing the rate of flow of fluid by the valve 63 decreases the pressure on the side of greater area. As soon as the pressure on the side of greater area again becomes one-halfthat acting against the stem lished and no further movement of the piston occurs until there is a further change in governing fluid pressure.

, It should be understood that in speaking of the relative areas of the stem portion 56 and the lower side of the piston 54: I have employed'the ratio of two to one for the purpose of illustration only and that any suitable ratios of area may be employed so long as a differential piston is employed. What I regard particularly as my invention is the employment .of a fluid motor for governing purposes operated by variable fluid pressure, said motor embodying a differential piston interposed in the path of the variable fluid pressure and effecting reciprocatory' movements responsive to variations in the governing fluid pressure.

From the foregoing it will be apparent that I have invented an improved fluid-pressure-actuated governing apparatus capable of close regulation of a prime mover.

While I have shown my invention in but two forms, it will be obvious to'those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications, without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims. I

What I claim is:

1. In a variable fluid pressure operated governing apparatus, a differential piston for effecting governing movements, means for admitting variable fluid pressure to the side of lesser area of the differential piston, means for by-passing fluid to the side of greater area, a pressure operated relief valve carried by the differential piston for determining the pressure onthe side of greater area, and a spring connecting the relief valve with a stationary part for modifying its action in accordance with the position of the differential piston.

2. In a variable fluid pressure operated governing apparatus, a differential piston for effecting governing movements, means for admitting variable fluidpressure to the side of lesser area of the differential piston, means for by-passing fluid to the side of greater area, a pressure operated relief valve carried by the differential piston for deter l'niningjtlle pressure on the side of greater area, a spring connecting the relief valve with a stationary part for modifying its action in accordance with the position of the differential piston, and means for adjusting the initial tension of the spring.

3. In a variable fluid pressure operated governing apparatus, a diflerential piston for effecting governing movements, means for admitting variable fluid pressure to the side of lesser area of the differential piston,

means for bypassing fluid to the side of greater area, a relief valve carried by the differential piston for determining theipresfor effecting governing movements, means for admitting variable fluid pressure to the side of lesser area of the differential piston, means for by-passing fluid to the side of greater area, a housing embodying a cylinder for the differential piston, a relief valve carried by the differential piston for determining the pressure on the side of greater area, said relief valve embodying a piston member subjected to the variable fluid pressure and a valve member subjected to the fluid pressure by-passed to the side of great or area, both of said pressures acting in a direction for opening said relief valve, and a spring connecting the relief valve with the housing for modifying the action of said relief valve in accordance with the position of the differential piston.

5. In a variable fluid pressure operated governing apparatus, a differential piston for effecting governing movements, means for admitting variable fluid pressure to the side of lesser area of the differential piston, means for by-passing fluid to the side of greater area, a housing embodying a cylinder for the differential piston, a relief valve carried by the differential piston for determining the pressure on the side of greater area, said relief valve embodyinga piston member subjected to the variable fluid pressure and a valve member subjected to the fluid pressure by-passed to the side of greater area, a spring for modifying the action of said relief valve in accordance with the position of the differential piston, an anchor for the spring secured to the housing, and

l at) motor-actuated means for moving the anchor'and changing the initial tension of the spring.

6. In a governing apparatus for a'prime mover, the combination of a differential piston for effecting govening movements, means for developing fluid pressure varying as a function of the speed of the prime mover, means for admitting the variable fluid pressure to the side of lesser area of the piston, said piston being arranged to permit a flow of fluid to its side of greater area, a relief valve carried by the piston and subjected to the fluid pressure for pair mitting a flow of fluid from the side of greater area of the piston and imposing a back pressure thereon, a housing and a spring disposed between the relief valve and the housing for varying the back pressure imposed on the differential piston in accordance with the position of said piston.

7. In a variable fluid pressure operated governing apparatus, the combination of a differential piston for effecting governing movements, means for admitting sure to the side of lesser areaof the piston, means providing an orifice for permitting a flow of fluid under pressure to the side of greater area, and means responsive to variable fluid pressure, to said fluid pressure on the side of greater area of the piston and to the position of the piston for imposing a lesser back pressure on the side of greater area. I

8. The combination with a prime mover, and a pump for developing fluid pressure varying with the speed of the prime mover, of a housing provided with a fluid inlet and a fluid exhaust, means for conveying fluid pressure developed by the pump to the housing, a hollow differential piston disposed within the housing and having its side of lesser area subjected to the pressure developed by the pump, said differential piston being provided with ports leading from the hollow thereof to the side of greater area and to the exhaust, a. movable element embodying a loose-fitting piston member and a valve member disposed within the hollow of, the differential piston, said loose-fitting piston member permitting a restricted flow of fluid under pressure from the side of lesser area of the diflerential piston to the side of greater area thereof and said valve member controlling the flow of fluid from the side of greater area to the exhaust, a spring associated with the movable element for opposing the variable fluid pressure and restricting the opening of the valve member, and a second spring disposed between the movable element and the housing for further varying the opposition to the variable fluid pressure in accordance with the position of the piston.

In testimony whereof, I have hereunto subscribed my name this fifteenth day of May, 1925.

OZRO N. BRYANT.

Images