US2160553A - Centrifugal governor - Google Patents

Description

530,- 1939- P. MARTINOTTI 2,160,553

' CENTRIFUGAL GOVERNOR Filed Jgne 3, 1936 2 Sheets-Sha e; l

og ww May 19394 P. MART II'\IOTTI 2,160,553

CENTRIFUGAL GOVERNOR Filed June '3, 1956 2 Sheets-Sheet 2 ily. a

I A ffarn Patented May 30, 1939 UNITED STATES: PATENT- OFFICE amm Application June s, 1930, Serial No. 83,245

In'Italy-June 17,1935

e Claims. (or. 264-19) The present invention relates to 'a-centrifugal governor which, although it is adaptable to various applications, is more particularly intended for controlling the'vaa'iable pitch propellers used in'aviation'. 4

The centrifugal governor according to the inventionis essentially characterised in that it comprises a fluid mass which rotates proportionallyto the speed of rotation of the machine or m apparatus to be governed, said mass, owing to its tendency to'centrifugate, increasing or decreasing in volume and thereby producing a suc tion or a' pressure on a piston or equivalent member connected to the control member of the i5 machine or apparatusto .be governed, said piston being displaced under the action of the said mass against the'reaction of an opposing force.

According to another characteristic of the invention, the force opposing the action of the fluid mass is influenced by the variations of pressure of the surrounding air.

The various characteristics of the invention -will become'apparent from the ensuing descriptiontaken in conjunction with the accompanymg drawings, in' which: 57

Fig. l. is a diagram'illustrating, according to a first embodiment, the technical principle of the- -.invention-,

Figs. 2 and 3 are views similar tothat of Fig. 1,

showing a modified embodiment;

Fig. 4 is a sectional view'of the centrifug al governor, r

Fig. 5 me plan view in part sectionof the centrifu'gal. governor, as applied to the control of a variable pitch propeller. I

,Fig. 6 is a view of a modifled form of the structure shown in Fig. 5;

Referring to Fig. l, the centrifugal governor comprises a reservoir i adapted to be rotated and provided with two radial extensions 2,

placed'in alignment with each other and being preferably of cylindrical shape. In each of the cylinders 2 is mounted ajpiston. 3 subjected to the action of a force P obtained, for example, by I means of a spring 4. In the reservoir I 'p'roper, is mounted a piston 5 which is subjected to the force exerted by a spring 6 or a system of springs, the force exerted by which can counterbalance the pressure due to the springs 4. The space between the pistons 3 and 5 is'filled with a heavy liquid, mercury for example.

when the apparatus isat rest, the pistons3 and 5 are in a position of equilibrium. On the contrary, whenthe apparatus rotates about the 5' axis oi the reservoircl, under the action of the variations of centrifugal force I which, "as is known, is proportional to the square oi. the speed of rotation of the apparatus, the pistons-3 move towards or away'from the axis of rotation. As a consequence, the piston 5 is forced in or 5 driven out.

The displacements of thepiston 6 can be used to actuate any member through the instrumen tality of links I, and for example, to vary the pitch of a propeller. 10 In the modification shown in Figs. 2 and 3, the springs 4 are replaced by a lighter liquid than the one with which the reservoir l is filled and, for example, by oil. The cavities filled with oil communicate with each other through ducts 8 Iii so that the pistons 3 and 5 are positively connected by the. liquid which unites their movements. In "said Figs. 2 and 3,'the apparatus is supposed to be mounted on the hub of a variable go pitch propeller, links 1 connecting the piston 5 to the rings 3 each supporting a bladelllof the propeller. In Fig. 4 a governor has been shown to which isapplied the principle described withreference g5 to Fig. l. The governor has a reservoir ll, provided at its front end with two radially disposed cylindrical extensions I! placed in alignment with each other. On each extension I! is mounted a sliding cylinder i3. Springs or pneuso matic boxes I exert a pressure on the cylinders 13, said springsor pneumatic boxes being inter,- posed between a flange 15 provided on said cylinders and the outer wall of each of two chambers l6 secured to the reservoir II and concentric s5 withflthe extensions l2.

Communication between the interior'of each extension I 2" and the corresponding cylinder I3- is ensured. by a syphon device, designated gen- .erally by H. V d 40 Within reservoir ii, and at its rear end, is mounted a piston i8 subjected to the action of a system of springs or of; a pneumatic box IS. The piston 13 is connected by. a linkage 20 to themember to be controlled. r

. Atdts front end, the reservoir II is cliised-by 2' a piston 2i subjected to the action of a force either to aspring 22, or to apneumatic box.

As previously mentioned, the reservoir II is filled with a heavy liquid, mercury for example; so

The portion of the reservoir H- between its -rear emh and the two extensions i2 is divided into twoeompartinents 23 and 24 by a closure device. The latter is composed-oi a partition 23 which is, fixed relatively to the reservoir ll 5i \3 which is provided at its centre with a duct 26 closed by a ball 21 subjected to the action of a spring 28. By means of this arrangement, the mercury can only pass from the compartment 24 to the compartment 23. The two compartments 23 and 24 furthermore communicate through a duct 29, controlled by a cylindrical slide valve 30 secured to a float 3| urged towards the rear ,'of

the reservoiri by a spring 32. In the position shown in Fig. 4, communication is established between the compartments 23 and 24.

The compartment -24 communicates with the chambers 33 formed between the sliding cylinders l3 and the extensions l2 through the syphons II.

The operation of the apparatus is as follows:

When the governor is rotated about the axis of the reservoir II, the mercury is subjected to the action of centrifugal force. A- part of the mercury which is contained in the compartment 24, then flows through the syphons intothe chambers 33. The quantity of mercury which thus acts on the ends of the sliding cylinders i3, against the action of the springs i4, increases or decreases proportionally to the speed of rotation of theapparatus.

When the mercury passes from the compart-' meat 24 to the chambers 33, the pistons l8 and 2| are forced in, piston 2| serving to absorb part of the variations in the volume of the mercury contained in the reservoir and thus decreasin the amplitude of the displacements of piston l8 which would otherwise be necessary to counteract such variations. On the contrary, when the mercury passes. from the chambers 33to the compartment 24, the pistons i8 and 2| are driven back. The displacements of the piston i8 are transmitted to the member to be actuated through the links 20.

The closure device connecting the compartments 23 and 24 only comes into play if the apparatus'takes up inclined position relatively to the horizontal plane passing through the axis of the reservoir If the apparatus tilts towards the rear, under the action of the float 3|, the slide valve 30 rises and closes the duct 29.

. The liquid contained in the compartment 23 no longer being able to pass into the compartment 24 the piston I8 is locked in the position which it occupies. ,In the case where the links 20 control the pitch of the blades of a variable pitch propeller, this arrangement creates a desirable condition whereby when the airplane assumes a certain inclination the pitch of the propeller will be maintained at -a given value. As soon as the apparatus returns to its horizontal position, the spring 32 brings the float 3| back to the position in which .the slide valve." keeps the duct 29 open.

It must be noted that if the members l4, l9 and 22 acting on the cylinders l3, I8 and piston 2|, consist of metal springs, the variationsof the pressure of the surrounding air have no influence on the operation of the governor.

On the contrary, if the members 14- and 22 acting on the cylinders l3 and piston 2| consist of pneumatic boxes having a certa'lnipressure within them and the member-l9 consists of a metal spring, it'is obvious that a decrease; or an increase in the pressure of the surrounding air will produce an increase or decrease in the action exerted on the cylinders i3 and piston. 1

On the contrary, if the members l4 and 22 consist of metal springs and the member 19 consists of a pneumatic box, the'action of the latter on thepiston l8 will decrease or increase accordmunication with the chamber 40, formed by the extension 36 and the corresponding cylinder 31,

through a syphon 4|. Each chamber 39 further-'- more contains a piston 42. On each cylinder 31 is mounted another mov able cylinder 43 held by springs 44,

The apparatus is completed either in the manner shown at the upper part of Fig. 5, or in' that shown at the lower part of Fig. 6.

0 In the first case, the cylinder 43 is provided with a bearing member 44' through whichis inserted the curved end of a lever 45 pivoted at 45 on the body 34 and connected by a link 41 to the moving hub 35 of the propeller. The curve of the end of the lever 45 is calculated as a function of the increase in volume of the liquid contained in the chamber 49 so that the amplitude of. the

oscillating movement of the said-lever 45 is constant.

In the second case, the cylinder 43 isi-extended by a cylindrical compartment 48 in which slides a piston 49 secured to the bearing member- 4 4'. The piston 49 is subjected to the action of -a pneumatic box 50 tending push-it back towards-the axis of the apparatus. According to the pressure of the surrounding air, the bearing member 44' will be moved closer to or further away from the axis of the apparatus.

The operation of the governor is as follows: When the apparatus-rotates about the axis XX, under the action of the liquid, the cylinders 31 are displaced against the action of the springs 38. The latter then transmit a force to the cylinders 43 which are also displaced, through a distance proportional to the difference in compression of the springs 38 and 44. a

In their displacements, the cylinders 43 rock the levers 45 which, through the instrumentality of the links 41, rotate the blades 35' and, consequently modify the pitch of the propeller.

The variation of the pitch of the propeller i therefore a function of the speed of rotation of the engine, said variation being eflfected in a completely automatic manner.

It is-possible, by an adjustment of the initial degree of compression of the springs 38 and '44 to determine the speed of rotation of the engine for which the governor will begin to operate. In order to take into account'the variations of pressure of the surrounding air, either pneumatic boxes 5| can be associated'with the springs 38,

or said springs 38 can be replaced by pneumatic ,boxes 52.

It is obviousthat the invention is in nowise limited to' the embodiments which have been more especially described by way of example, butthat it extends to all possible modifications coming, fairly, within the scope of the appended claims.

Iciaim: l. A centrifugal governor comprising a. rotating element having a plurality of hollow radial extensions, elements telescopically mounted with respect to said extensions, forming a watertight to variations in the governor comprising a rotat- 55, proportional to' the ts of 2. A centrifugal element having a plurality of hollow radial extensions, elements telescopically mounted with respect to said extensions, forming a watertight 5 movable closure therefor, a liquid mass within formed, responsive to the acelement, an additional element telescopically mounted with respect to each of said first mentioned telescopically mounted elements, elastic rotating element scopically mounted elements, tending to oppose ment or said control element in a ratio d last mentioned 'teieseopically"mountcd el cuts.

4. A centrifugal governor a rotatmeans interposed between said and said second mentioned telev with respect to the former, scopically mounted with as to hold t e liquid mass telescopi ally V 3 ing element having a plurality of hollow' radial extensions each having a Syphon-like passage I leading to the outer end thereof, a cylinder telescopically mounted upon each extension, forming a watertight collapsible and extensible chamber therewith, ,a liquid mass within each chamber,

( responsive to the action of centrifugal force to.

displace said telescopically mounted cylinders, elastic means tending to force said telescopically mounted cylinders inwardly so as to hold the liquid mass'to a constant volume, and a control element responsive to the displacements of said telescopically mounted cylinders.

5. A centrifugal governor comprising a rotate ing reservoir having an axial extension and a voir, and extensions, elastic means tending to force said telescopically mounted cylinders and said piston inwardly so as to hold the liquid mass to a constant volume, a partition within said axial extension .interposed between said piston and said reservoir, said'partition being provided with a through passage, a check valve permitting liquid to flow from said reservoir towards said pisflowing in the opposite dia by-pass between said through passage and said reservoir, a float actuatedvalve controlling said by-pass, and a' control element operatively associated with said piston.

6. A centrifugal governor comprising a rotatting element having a an element telerespect to each exten-. sion, forming a watertight movable closure therefor; a liquid mass within each chamber thus i'ormed responsive to the action of centrifugal force to displace said telescopically 'mounted element, elastic means interposed between each telescopically mounted element and its corresponding primary control element, tending to force said telescopically'mounted element inwardly so as to hold the liquid mass to a constant volume, operative]! asand a secondary control element sociated'with said control elements.

pluralityoi. hollow radial

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