Improvements in Automatic Regulating Apparatus for Steam. Engines.
Year: 1893

page_text: Date of Application, 30th Oct., 1893-Accepted, 2nd Dec., 1893
Improvements in Automatic Regulating Apparatus for Steam.
Engines.
We, JOHN WHYTE, HENRY WHYTE, and ARTHUR WILLIAM COOPER, all
of the firm of J. & H. Whyte and Cooper, Britannia Engine and Boiler Works,
East Dock Street, Dundee, in the County of Forfar, Scotland, Engineers, do
hereby declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:—
This invention relates to apparatus for automatically varying the expansion of
the steam in steam engines according to the position of the governor, and has for
its main object the easy conversion of existing steam engines having only one slide
valve, into engines with automatically variable expansion, but it may also be
advantageously applied to new engines.
The description of our improvements is assisted by two sheets of explanatory
drawings, hereunto appended and hereinafter referred to.
Figure 1. (Sheet 1.) is a part sectional elevation at A. A. (Figure 2.); Figure 2.
a side elevation; and Figure 3. a plan of the regulating apparatus.
Figure 4. (Sheet 2.) is a view looking on B. (Figure 5.); and Figure 5. is a side
elevation showing on an enlarged scale, the trip gear of the apparatus.
In these drawings the same reference numerals are used to mark the same or
like parts wherever they are repeated.
The apparatus acts in such a manner, that at the beginning of the piston stroke of
the steam engine, steam is admitted into the valve chest containing the main or slide
valve at full pressure and that according to the position of the governor (not shewn
in the drawings), the steam is cut off sooner or later.
The effect of the apparatus is therefore similar to that of the valve gear of
ordinary steam engines with automatically variable expansion, except that the
steam contained in the main valve chest takes part in the expansion, which occurs
twice in every revolution of the engine.
The special construction of this apparatus whereby it differs essentially from
other apparatus for the same purpose is as follows:-
Fresh steam is admitted from the boiler through the casing 10. into the main
11. is a
valve box, preferably in the direction of the arrows Figures 1. and 2.
small stop valve which is used to permit the steam to blow through from the boiler
to the valve chest before the engine is started and therefore before the valve 12. is
opened, such valve 11. being closed when the cylinder of the engine is fully
heated. The double beat valve 12. is lifted off its seat twice in a revolution when
the crank is at or about its dead centres, by means of the engine eccentric, or
like gear, actuating the rod 13. and the other trip gear mechanism connected
therewith.
The function of the trip gear mechanism is to render the cut-off dependent on
the speed of the engine, and hence on the position of the governor, and is
constructed in the following manner :-
The lever 14. is caused to oscillate through a sector of a circle by means of the
reciprocating rod 13. which in turn causes the extremities of the levers 15. and 16.
to be alternately elevated and depressed, and consequently the pawls 17. and 18. to
be alternately depressed and elevated. When say the pawl 17. is being depressed,
a tension spring stretched between the fixed point 19. and the tipping lever 20.
draws the point of such tipping lever into a recess 21. as shewn, and keeps it there
until its other extremity comes in contact with the adjustable stud 22. upon which
the extremity which is in the recess 21. is withdrawn and caused to slide further

page_text: back upon the lever by means of the tension spring. As long as the extremity
of the tipping lever 20. is in the recess 21. the pawl 17. is clear of the pawl 23. on
the lever 24; but whenever it is taken out of such recess by touching the stud 22,
the pawl 17. is drawn forward until it is ready to engage with the lever 24. by the
same movement which draws back the tipping lever. In its upward travel it
therefore lifts the lever 24, which in turn lifts the valve 12. by means of the central
spindle 25. This valve 12. is made to close rapidly by means of the tension
springs 26; 27. being a dash pot employed to cushion its contact with the seat.
The time of release of the lever 24. is determined by the governor, a rod from it
being coupled to the bell crank 28. thus determining the position of the stops 29,
against which the levers 30. strike when they are being raised by the levers 15.
or 16. and their appurtenances; thus causing the pawls 17. or 18. to be drawn
back, leaving the lever 24. free to fall and with it the valve 12. The position of
one of the stops 29. may be adjusted by means of the pinching pins 31. and the
lever 32. The highest position of the stops 29. may also be determined by means
of the adjustable stop 33, in this manner cutting off the steam at a definite
maximum part of the stroke. It is to be understood that 33. is an emergency stop,
and that the bell crank 28. in ordinary circumstances will not touch it unless
something happens to the
governor.
Where the bracket 34. is fitted to the other 35, the construction is such that 34.
may be turned about the axis of the central spindle 25. and fixed in any suitable
position by means of pinching screws.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
(1) In apparatus for automatically varying the expansion of the steam in steam
engines according to the position of the governor, the combination of a double beat
valve 12. and its appurtenances, adapted to admit and cut off steam at each end of
the cylinder alternately by means of trip gear mechanism, set in motion by the
eccentric or equivalent moving part of the engine, substantially as hereinbefore
described and illustrated on the accompanying drawings.
(2) In apparatus for automatically varying the expansion of the steam in steam
engines according to the position of the governor, the described combination of
disengaging gear, such combination consisting of the levers 15. and 16, the
pawls 17. and 18, tipping levers 20, adjustable studs 22, lever 24, central spindle 25,
variable stops 29, and levers 30, substantially as described and illustrated.
(3) In apparatus for automatically varying the expansion of the steam in steam
engines according to the position of the governor, the combination of the adjustable
pinching screws 31. and lever 32. as described and illustrated.
(4) In apparatus for automatically varying the expansion of the steam in steam
engines according to the position of the governor, the combination of the adjustable
stop 33. with the bell crank 28, as described and illustrated.
Dated this 28th day of October 1893.
GEO. C. DOUGLAS & Co.,
41, Reform Street, Dundee, Agents for Applicants.