US2577052A - Centrifugal governor or other mechanism requiring sensitive motion transmission - Google Patents

Description

Dec. 4, 1951 D. N. WALKER CENTRIFUGAL GOVERNOR OR OTHER MECHANISM REGUIRING SENSITIVE MOTION TRANSMISSION Filed Aug; 24, 1945 Edd 11%! I Patented Dec. 4, 1951 CENTRIFUGAL GOVERNOR OR OTHER MECHANISM REQUIRING SENSITIVE, MOTION TRANSMISSION Daniel Norman Walker, Ashby Parva, near Rugby,

England, assignor to Power -Jetl.(Research 8: Development) Limited, London, England Application August 24, 1945, Serial No. 012,344

- In Great Britain mm 20, 1941 Section 1, Public Law 690, August a, 1m Patent expires October 20, 1961 1 Claim. (Cl. 264) This invention relates to centrifugal governors in which it is required to transmit motion with a high degree of sensitivity. Such devices, when a high degree of precision is required in operation. are found to require in some cases that provision be made to avoid or reduce the effects of static friction, sticking to local binding of moving parts, and so on. The invention seeks to provide means for keeping the moving parts live" to a suflicient extent to .ensure good operation, without introducing undue complexity. This is of advantage in such cases as that of a speed governor on a very smooth-running engine, e. g., a steam or gas turbine; the need on a rougher engine such as a, reciprocating engine, is less marked, because the ambient vibration is generally sumcient to prevent the governor from sticking.

It has been proposed previously to provide means for impartin oscillation to the valve mechanism of centrifugal governors to avoid or reduce the effects of static friction, and thus to increase sensitivity. Consequently, no claim is made to any such device broadly.

By the present invention there is provided in a centrifugal governor including valve means actuated by the axial movements of a rotating governor spindle, a cam-like or swashplate-like for-, mation on or rotating with the governor spindle so as to impose on the valve means and parts moving therewith an oscillatory motion of small amplitude compared with the working movement thereof, by virtueof the rotation of the spindle. The valve is preferably moved by the spindle through the medium of a rocker against one end of which the governor spindle bears, and the oscillatory effect is applied both 'to valve and rocker, keeping them both live. The oscillatory'movemnt is small compared to the working movement; this comparison of course involves a consideration of the shape and design of the port or ports controlled by the valve as well as other matters, but in general it is to be understood that the amplitude of the oscillatory movement should be insignificant in its effect on the function of the valve as a valve, whilst involving some sliding of the valve to ensure against it being bound by static friction with consequent possibilities of erratic or unstable action.

The invention will now be described with reference to the accompanying drawing, which is diagrammatic in nature and necessarily exaggerated for the sake of clarity.

Fig. 1 illustrates a typical arrangement of governor to which the invention is applicable.

Fig. 2 illustrates the oscillating means in one example, and an arrangement for the provision of satisfactory bearing.

In Fig. 1, a casin 1 houses the centrifugal mass consisting of flyweight arms 2 rotated by a driving spindle 3 and so pivoted at 4 that their tails 2A bear substantially axially against a collar 5 (resisted by spring 8) which is on a governor spindle l which rotates with the driving spindle 3. Suitable bearings and other details are of course provided. The end of the spindle I projects from the casing I and bears against one end of a rocker 8 the other end of which bears on the end of a valve stem 9 carrying a sliding valve ill in a ported cylinder II. The valve I0 is thrust by a spring i2 against the rocker 8, whereby the abutting surfaces between 1 and 8, and 8 and 9, are kept in contact and backlash or looseness is avoided. It will be appreciated that Fig. l is a formal rather than an exact representation of a governor; the invention not being dependent on the exact design of governor providing the essential elements are present.

The end of the governor spindle I is formed as a miniature swashplate where it bears on the rocker 8. Thus as the spindle rotates it oscillates the rocker and the valve. The angle of swash is of a very small order, for example such as to cause the valve to move .01" per revolution of the spindle 1. Such an angle is too small to be shown on this drawing.

Fig. 2 indicates an anti-wear type of bearing between spindle l and rocker 8. The rocker I has a hardened steel insert 8A with a'flat-faced head 8B to bear on the swashed end of the spindle l. The angle of inclination or swash of the end of the spindle I is indicated (exaggeratedly) at A. It will be seen that a smooth sinusoidal oscillation of the rocker is caused by the rotation of spindle 1, and the oscillation effeet on the rocker 8 is due to what is in effect the change of radius (from the axis of the rocker fulcrum) at which the contacting part of the spindle-end bears against the rocker 8, or against .the. head 8B, and the angle A should therefore be greater than the angle which the head, or rubbing face, of the rocker, can make to the axis of the spindle I, in any normal operative position, if such smooth oscillation is desired, whilst the position of the lever is such that the plane of the face on the head 83 is at an angle other than referred to the axis of the spindle I.

The swashed end of the spindle can be regarded smegma 3 as a convenient way of providing an eccentric high spot" on the end of the spindle 1.

It is assumed that the masses of end load due to the various parts will be designed to be such that the reaction in the spindle I of the oscillatory forces it applies to the rocker will not be such as to aifect the operation of the governor, or to excite am; untoward natural frequencies or to cause undue wear for ei rample on the pivots 4.

I claim:

In centrifugal governor mechanisms for controlling the movement of a device through a lever system in accordance with the movement of the governor on change of speed; an oscillatory means for preventing the governor or device from sticking comprisins a spindle arranged on said governor for rotation therewith and for axial movement on the axis thereof onrchanse of speed 4 to actuate said lever system and device and having a swashplate end formation for imparting a constant and continuous oscillatory movement between said governor, lever system and device during rotation of said governor.

DANIEL NORMAN WALKER.

REFERENCES CITED The following references are of record in the 10 file of this patent:

UNITED STATES PATENTS

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