US1805972A - Fluid pressure governing mechanism - Google Patents

Description

May 19, 1931- o. N. BRYANT ET AL 1,805,972

FLUID PRESSURE GOVERNING MECHANISM Filed March 28, 1929 I l i l i WITNESS i! n lNvENToRs il OJl-Blg/au 8|: li l i Archwendm p l I BY a' @.PW

ATTORNEY Patented May 19, 1931 UNITED STATES OZRO N. BRYANT, OF MOORES, AND ANTHONY F. SCHWENDNER, OF ESSINGTON, PENN- SYLVANIA., ASSGNORS TO WESTNG-OUSE ELECITRIO AND MANUFACTURING COM- PANY, A CORPORATION OF PENNSYLVANTAl FLUID PRESSURE GOVERNNG IJIECI'IAN IS1VI Application filed March 28, 1929.

Our invention relates to a governing mechanism for a prime mover, more particularly to a fluid pressure governing mechanism, and it has for its object to provide improved operation thereof.

A more specific object is to sluit off the supply of motive fluid to the prime mover upon a failure or predetermined minimum pressure of the fluid supplied to the pressure developing mea-ns of the governing` mechanism.

In a fluid pressure governing mechanism having a fluid pump of the pressure type, such as a centrifugal impeller, the pressure delivered by the pump is the sum of the pressure developed by the pump added to the pressure of the fluid supplied at the inlet of' the pump. In order, therefore, to obtain reliable governing, it is desirable to safeguard against a possible failure or diminution of the inlet pressure.

In accordance with our invention, we provide an impeller receiving fluid at positive pressure, that is, above atmospheric pressure, and a fluid pressure relay for controlling the admission valve of the prime mover. The

relay includes a pressure-responsive element, preferably the pilot valve, which is responsive to the fluid pressure delivered by the pump and which issubjected torfiuid pressure in the direction for increasing the admission valve opening. We provide a valve which releases the fluid pressure acting on the pressure-responsive element in valve opening direction, upon a predetermined minimum pressure of the fluid at the inlet of the pump, thereby unbalancing the forces acting on the pressure-responsive element and causing the saine to move in valve-closing direction.

The above and other objects are effected by our invention, as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

rlhe single figure of the drawing is a diagrammatic view showing a governing system embodying our invention, parts thereof being shown on an enlarged scale.

Referring now to the drawing more in detail, we show our novel governing mecha- Serial N0. 350,603.

nism applied to a prime mover, of which is shown only a portion of the rotor shaft 10, and a portion of the bearing housing,'11, containing a journal bearing 12 for the shaft;v

An admission valve 13 controls the admission of motive fluid to the prime mover.

The fluid pressure governing mechanism is supplied with fluid pressure varying asV from the discharge annulus 16 of the pump,

through a conduit 19, and delivers fluid at a positive pressure to the chamber 15, through a conduit 21. Lubricating fluid is also conveyed through the conduit 21 to the bearing 12.

The admission valve 13 is actuated by a fluid pressure relay, including an operating piston 22 connected to the valve 13 by means of a stem 20, and a pilot valve 23 for controlling the operating piston. The lstationary housing structure of the` relay includes a cylinder 24. in which the piston 22 operates and a sleeve25 forming-a valve casing for the pilot valve 23. The cylinder 211 contains springs 56 which bias the piston 22 downwardly in valve-closing direction.

The sleeve25 is formed with annular rows of ports 26 and 27 communicating with the cylinder 24;, above and below, respectively',

of the travel of the operating piston 22.

The sleeve 25 is furtherV provided With ports 28 disposed between the rows of ports 26 and 27, and communicating with a chamber 28, which is supplied with fluid pressure from any suitable source through an inlet opening 29. Above and below, respectively, of the ports 26 and 2?, the sleeve 25 is provided with rows of ports 31 and 32, communicating with a discharge chamber 30, having an outlet opening 33.

The pilot valve is provided with piston portions 311 and 35 which cover the annular rows of ports 26 and 27, when the pilot valve is in normal cut-off position. It is also provided with piston portions 36 and 37 at its upper and lower ends.

A tension spring 38, connected "at its upper end to the pilot valve, is disposed within the sleeve 25 and biases the pilot valve downwardly. The lower end of the spring is attached to a stem 39, extending Vthrough the lower endof the pilot valve casing and pivoted to a lever 41 intermediate the ends thereof. One end of the lever 4- 1 is pivoted to a stationary part, and the other end is pivoted to the stem 20.

The' pilot valve is biased upwardly by the fluid pressure delivered by the pump 14, which is transmitted to the lower end of the pilot valve casing through a conduit 42.

y The pilot valve is biased downwardly Vin opopening 155.

position to the impeller pressure, by the pressure in the chamber or enclosed space 43, which receives a lrestricted flow of fluid through a restricted orifice 40 in the pilot valve. The pressure in this chamber is controlled by a pressure relief valve 44, which is biased to closed position by a spring 45. A lever '46' is provided tok actuate a spring abutment 47, by means of which the compression or setting of the spring 45 may be varied.

The chamber 43 communicates with a drain chamber 48, through an opening 49 which is controlled by'` a piston valve 51. The chamber 48 is provided with an outlet A pressure-responsive Vpiston 52 is connected to the piston valve 51 and is biased upwardly by a spring 53. It is biased downwardly by the pressure in the conduit 21, which is communicated to the chamber 54 abovethe piston 52, and which is the pressure of the fluid supplied to the pump 14. y

The operation of the above-described embodiment is as follows:

Fluid flowing by gravity from the reservoir 17 and motivated by fluid pressure from the pump 14, is delivered by the ejector 18 to the conduit 21 at a positive pressure, for example, 7 pounds per square inch. A From the conduit 21, fluid is supplied'at said pressure to the inlet of the pump 14, through the chamber 15, `and to the bearing 12.

The lfiuid pressure discharged by the pump 14 is conveyed to the pilot valve 23 to bias the same upwardly. This pressure varies substantially as the square of the speed ofthe prime mover. A portion ofthe fluid `flows through the restricted orifice 40 and builds up a pressure determined by the pressurerelief valve 44. This pressure, which may, for convenience, be termed the second fluid pressure` is constant for a given "speed setting, and biases the pilot valve23 downwardly in opposition tothe pump pressure. The spring 38 is designed to balance the excess of the pump pressure over the second fluid pressure.

Upon an increase in speed, the fluid pressure discharged by the pump 14 is increased and -moves the pilot valve 23 upwardly. Fluid pressure is thus admitted to the upper end of the cylinder 24 through the ports 28 and 26, and discharged from the lower end of the cylinder through the ports 27 and 32. The piston 22, therefore, moves downwardly to decrease the opening of the admission valve 13. The lever41 is carried downwardly at the same time, and returns the pilot valve 23 to cut-olf position.

Upon decrease in speed, the mechanism opcrates in the reverse manner to increase-the valve opening and the motive Huid admission, as will be readily apparent to those skilled in the art.

As long as the pump inlet pressure is of a predetermined minimum value, the piston 52 is held down and the piston valve 51 covers the opening 49. ln case said pressure should diminish below the predetermined value, the spring 53 moves the piston 52 and the piston valve 51 upwardly, thereby uncovering the opening 49.

The second fluid pressure in the chamber 43 is thus released, the fluid escaping to the drain chamber 48. The pump pressure acting on the pilot valve 23 now exceeds the force of the spring 38, and moves the pilot valve upwardly.` As explained above, upward movement of the pilot valve results in closing movement vrof the admission valve 13. The admission of motive `fluid to the prime mover is thus shutoff.

rThe minimum pressure in the chamber 43 is so chosen that when 'the pressure therein is released, the pump pressure effects a 'sufficient elongation ofthe spring 38 to eect closing ofthe admission valve 13.

From the above description, it will be seen that we have provided a fluid pressure governing mechanism having provision for shutting lvoff the 'admission of motive fluid upon a predetermined diminution in pressure o'r failure of the fluid supply for the ressu're developing means.

lVhil'e we have shown our invention in but one form, it will be obvious to those skilled in thek art that 'it is not so limited, but is Asusceptible of Vvarious changes and modifications without departing from the spirit thereof, and we desire, therefore, lthat only such limitations shall be placed thereupon as are imposed by the prior art or as are spec'ically set forth in "the appended claims.

lVhat we claim is:

1. In a governing mechanism for a prime mover having an admission v'alve, the `vcombination of means providing fluid Vpressure varying as a function of an loperating condition of lthe prime mover, 'a fluid pressure relay for controlling the admission valve and including an operating piston and an element responsive to said variable fluid pressure for controlling the movements of the operating piston, said pressure-responsive element being biased in valve-closing direction and being biased by fluid pressure in valve-opening direction, and valve means responsive to an abnormal operating concition of the prime mover for releasing the fluid pressure acting on said element in valvep direction, and valve mea-ns responsive to an abnormal operating condition of the prime mover for releasing the fluid pressure acting on said element in valve-opening direction.

3. In a governino` mechanism for a prime i mover having an admission valve, the combination of means providing fluid pressure varying in response to the speed of the prime mover, a fluid pressure relay for controlling the admission valve and including an operating piston and an element responsive to said variable fluid pressure for controlling the movements of the operating piston, said pressure-responsive element being biased in valve-closing direction and being biased by fluid pressure in valve-opening direction, and valve means responsive to a minimum pressure of the fluid at the inlet of said fluidpressure providing means for releasing the fluid pressure acting` on said element in valve-opening direction.

Ll. In a governing mechanism for a prime mover having an admission valve, the combination of means providing fluid pressure varying as a function of the speed of the prime mover, means providing a supply of fluid to said means, a fluid pressure relay for controlling the admission valve and including an operating piston and an element responsive to said variable fluid pressure for controlling the movements of the operating piston, said pressure-responsive element being biased in valve-closing direction and being biased by fluid pressure in valve-opening direction, and valve means responsive to "the supply of fluid to the mst-mentioned means for releasing the fluid pressure acting on said element in valve-opening direction.

5. In a Huid pressure governing mechanism for a prime mover, the combination of means providing a fluid pressure varying as a function of an operating condition of the prime mover, means providing a supply of fluid to said means, fluid pressure relay means controlling the admission of motive fluid to said prime mover and including a control element responsive to said fluid pressure, means biasing said element by a second fluid pressure in the direction for increasing the motive fluid admission, and means responsive to the supply of fluid to the firstmentioned means for releasing said second fluid pressure.

6. In a fluid-pressure governing system for a prime mover having an admission valve, the combination-of a pump providing a fluid pressure varying With the speed of the prime mover, a fluid pressure relayforV the admission valve including a pressureresponsive control element, means for applying the fluid pressure provided by said pump to said element in valve-closing direction, means for applying a second pressure to said element in valve-opening direction and in opposition to the first-mentioned pressure, and means responsive t-o a predetermined minimum fluid pressure at the inlet of said pump for releasing said second pressure.

7. In Va fluid-pressure governing system for a prime mover having an admission valve, the combination of a pmnp providing a fluid pressure varying With the speed of the prime mover, a fluid pressure relay for the admission valve including a pressureresponsive control element, means for applying the fluid pressure provided by said pump to the pressure-responsive element in valveclosing direction, means for applying a second fluid pressure to said pressure-responsive element in valve-opening direction and in opposition to the first-mentioned fluid pressure, and means responsive to a predetermined minimum fluid'pressure at the inlet of said pump for releasing said second fluid pressure.

8. In a fluid pressure governing system for a prime mover having an admission valve, the combination of a centrifugal pump driven by the prime mover, admission valve including a pressure-responsive control element, means for applying the pressure provided by said pump to one side of the pressure-responsive element in valveclosing direction, means providing a vrestricted flow of the fluid discharged from said pump to the opposite side of said pressure-responsive element, means controlling the escape of fluid from said opposite side and imposing a back pressure thereon, means for supplying fluid under positive pressure to the inlet of the pump, and means responsive to a predetermined minimum value of said last-mentioned pressurefor releasing said back pressure.

9. In a fluid pressure governor for a prime mover, the combination of fluid translating means providing a governing Huid pressure a fluid pressure relay for the l varying as a function of an operating condition of the prime mover, means forsupply'ing fluid at positive pressure at the inlet of said fluid translating means, fluid pressure relay7 means controlling 'said primemover and including a control element responsive to said governing fluid pressure in one direction, means for applying a second fluid pressure to said element in opposition to the governing fluid pressure, and means releasing the second fluid pressure Ionsaid element upon a decrease of the pump inlet pressure below a predetermined value.

l0. In a fluid pressure governor for a machine, the combination of means including a pump providing a fluid pressure varying as a function of the speed of the machine, means for supplying fluid at positive pressure at the inlet of said pump, a pressureresponsive element subjected to said fluid pressure, a fluid pressure relay controlled by said element for governing said machine, means for applying a back pressure on said element in opposition to said first-mentioned fluid pressure, and means responsive to the inlet pressure of said. pump for releasing said back pressure.

11. In a fluid pressure governor for a prime mover having a rotary shaft, the combination of a vpump having an impeller mounted on said shaft, means for supplying fluid under positive pressure to the inlet of the pump, said pump developing a governing fluid pressure varying as the square of the speed of the Vprime mover, a fluid pressure relay including a pilot valve and a pilot valve casing for controlling the admission of motive fluid to said prime mover, means for transmitting said governing fluid pressure to `one end of said casing to bias the pilot valve in the direction 4fordecreasing the admission of motive fluid, means providinga fluid pressure in the other end of said casing acting on said pilot valve in opposition to the .govern- .ing fluid pressure, and a valve adapted to release the fluid pressure in said other end-of said casing upon decrease of said pump inlet pressure below a predetermined value.

12. In a governing mechanism for a prime mover having a bearing, means for supplying lubricating fluid under pressure to `the bearing, and an admission valve, the combination of means providing fluid pressure .varying as a function of the speed of the prime mover, a fluid pressure relay for controlling the admission valve and including an operating piston and an element responsive to said variable fluid pressure for controlling the movements of the operating piston, said pressure-responsive element being biased in valve-closing direction and being biased by fluid pressure in valve-opening direction, and valve means responsive to a lminimum pres- Asure of the lubricating fluid supplied to the bearing for releasing the fluid pressure acting on said element in valve-opening direction.

13. In a governing mechanism for a prime mover, the combination of means providing a governing force varying as a function of an operating condition of the prime mover, fluid pressure relay means controlling the admission of motive fluid to said prime` mover and including a control element responsive to said governing force, means biasing said element by a second force in the direction for increasing the motive fluid admission, and means responsive to an abnormal operating condition of said `prime mover for releasing said second force.

In testimony whereof, we have hereunto subscribed our names this 16th day of March,

OZRO N. BRYANT. Y ANTHONY F. SCHVENDNER.

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