Improvements in Governing Apparatus for Screw-propeller Engines.
Year: 1894

page_text: Date of Application, 28th Aug., 1894-Accepted, 29th Sept., 1894
Improvements in Governing Apparatus for Screw-propeller
Engines.
I, GYSBRECHT HENDRIK JOHAN VAN AMSTEL, of 9 Burmanstraat, Amsterdam,
Holland, Engineer, 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 :-
The present invention relates to improvements in the well-known Dunlop
governor which is used on board screw-propeller ships for automatically con-
trolling the engines in rough weather when the ship is pitching and the propeller
at the stern is more or less immersed.
My said improvements principally consist in a better arrangement of the valve
of the relay-cylinder, and in the manner in which the valve-rod of the said
cylinder is actuated through the primary apparatus itself, and in the combination,
with the piston-rod of the relay-cylinder, of an air-pump, which, at every down
stroke of the said piston-rod, forces air into the air-pipe of the primary apparatus
and into the air-vessel situated at the stern of the ship.
The valve-rod of the Dunlop governor is connected directly to the rod of the
primary apparatus, which moves up and down, so that the valve and likewise also
the pistou of the relay-cylinder which is connected with the throttle or regulating
valve of the main engines, continually participate in the up and down movement
of the rod of the primary apparatus, corresponding to a greater or lesser immersion
of the ship's stern.
In consequence of this arrangement, the flow of steam to the main engines is
constantly being varied, with the result that the steam is partially cut off even if
the propeller is not yet in such a position as to require a readjustment or regulation
of the main throttle-valve. Under these circumstances, the engines generally run
at only half power and the speed of the steamer is reduced more than is really
necessary. According to the present invention, this defect is avoided by not
connecting the valve-rod of the relay-cylinder directly to the primary apparatus,
and by arranging the valve of the relay-cylinder in such a manner that it is always
forced into its lowermost position by the pressure of the steam. By so doing the
valve is only actuated in the lower positions of the flexible diaphragm of the
primary apparatus, as, for example, when the ship's propeller is partly or totally
lifted out of the water and closing of the throttle-valve is necessary.
The piston of the relay-cylinder then makes its full stroke, since the steam-valve
is not returned by the movement of the piston, as is the case in the Dunlop
governor. In this way, the throttle-valve is fully closed as soon as the relay-
cylinder valve has admitted the steam to the cylinder and is opened again as
hereinafter described by the return stroke of the piston as soon as the flexible
diaphragm is forced up again by the increased pressure of the air in the main pipe.
Another defect of the Dunlop governor is the constant leakage of the air in
the long main air-pipe from the ship's stern to the primary apparatus in the
engine-room.
The slightest reduction in the pressure of air in this main pipe caused by leakage
interferes with the proper operation of the regulator and if the pressure falls still
more its operation is totally stopped.
According to my present invention, this difficulty is obviated by using an
air-pump which is directly connected to the relay piston-rod, so that a quantity of
air is forced into the main air-pipe with every downward stroke of this piston.

page_text: In this manner, the pressure of air in the main pipe is constantly restored or
maintained even in cases where considerable leakage takes place in the main
air-pipe and the proper working of the governor is thus ensured.
If too much air is forced into the main air-pipe by the air-pump, this air is
automatically discharged through the opening of the air-chamber in the ship's
stern.
In the accompanying drawing
Figure 1 is a vertical section, and
Figure 2 a plan of the improved apparatus, and
Figure 3 is a vertical section of the relay-cylinder and valve-chest drawn to an
enlarged scale.
The primary apparatus A with its dish-shaped chamber B is connected to the
same frame as the relay-cylinder C and air-pump D near the lower part of the said
air-pump.
The main air-pipe a communicates with the air-chamber in the ship's stern and
this pipe opens into the bottom of the dish-shaped chamber B, so that the air
acts on the under side of the flexible diaphragm b (shown in the drawing in its
lowermost position) which is fixed to the rod E. Between the upper part of
the primary apparatus A and the diaphragm b is situated the spring c which assists
in the downward movement of the diaphragm.
The compression of this spring may be adjusted by means of a gland d. The
rod E passes through this gland and through an aperture fin the lever F and is
provided at or near its upper end with a collar G secured to it by a screw,
which collar presses down the lever F in the downward stroke of the diaphragm b.
The lever Fis mounted on a bracket F' on the frame of the apparatus, the other
end f being of oval shape and bearing against the lower end of the valve-rod g
of the relay-cylinder C. The lever F is also provided with a handle f* to move
it by hand in order to start the apparatus as hereinafter described. The steam-
valve H, shown on an enlarged scale in Figure 3, is of the piston class. The
steam ports or passages h, h₁ of the cylinder C are made moderately small in
order to give the piston a gentle or slow motion. As the uppermost surface of
the valve is of larger area than the undermost one, the pressure of the steam,
which is admitted through the port k and exhausted through the port 1, always
tends to force down the valve. A hole is provided, to permit the boring of the
lower steam-port or passage h', the upper steam-port or passage h being bored
through the port l.
The pistons of the relay-cylinder and air-pump are fixed on the same piston-
rod K.
This piston-rod is provided with a crosshead m slotted on both sides, iu
which works a lever L provided with pins n. The lever L is mounted on a
rock-shaft M on which is fixed a slotted lever N. In the slot of this lever is
adjustably secured a rod O which connects this lever with the throttle-valve of the
main engines, and in this way the movement of the piston of the relay-cylinder is
communicated to the said throttle-valve.
The air-pump cylinder D is provided at its lower end with an air-inlet valve p
and with a delivery valve r kept normally closed by a spring.
The casing of this valve communicates by a ports with the bottom of the
dish-shaped chamber B, so that, at every downward stroke of the air-pump piston,
air is forced under the diaphragm b and into the main air-pipe a.
The upper part of the air-cylinder is provided with apertures t and v, controlled
by cocks, the aperture t being somewhat larger than the aperture v. As soon as
the piston in its upward stroke covers the aperture t, the air is compressed, and, by
keeping the air-cocks at t and closed or partly closed, the piston is air-cushioned
at the end of its upward stroke as required.
The piston may be air-cushioned at the end of the downward stroke by
regulating the stroke of the valve by means of the set-screw w acting on the
end of the spindle of the suid valve. In this way, the movement of both pistons
is rendered gentle and shocks are prevented.

page_text: The air-pump piston offers no resistance to motion during its upward stroke,
i.e. during the closing of the throttle-valve; but the downward stroke of the said
piston takes more time by reason of the air being forced past the valve r, so that
the throttle-valve is gently or gradually reopened.
The main air-pipe and the air-chamber are of the usual construction, the opening
of this chamber in the ship's stern should be made wide and the total capacity of
the air-chamber is to be made about the same as that of the main airpipe a and the
dish-shaped chamber B in the uppermost position of the diaphragm b.
The position of the diaphragm, pistons and levers shown in Figure 1 of the
drawing, is that which they assume when the ship's stern is lifted and the propeller
partly or totally raised out of the water.
The lever F has been drawn downward by the rod E, and its other end f¹ has
pressed the valve H upward so that the pistons of the relay-cylinder and air-pump
have made their upward stroke, and, by so doing, have closed the throttle-valve of
the main engines by means of the levers L, N and the connecting rod 0; as soon
as the ship resumes its normal position the air in the air-chamber and main air-
pipe a is compressed and moves the diaphragm and its rod E upwards until they
are in their uppermost or normal position.
The lever F being now released, its other end f' is forced down by the downward
pressure of the steam acting on the end of the valve-rod g, which movement of the
valve opens the uppermost steam-port (Figure 3) and causes the piston to make
its downward stroke, thus gently opening the main throttle-valve and pumping
a quantity of air into the main air-pipe a.
The position of the collar G on the rod E is somewhat above that of the
lever F in its uppermost position, so that small downward movements of the
diaphragm and of the rod E do not cause the main throttle-valve to be closed.
In order to start the apparatus, the lever F is moved up and down by the
handle f in order to fill the air-pipe with air and to warm the cylinders.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
1st. A governing apparatus of the kind or class hereinbefore referred to,
constructed substantially as herein before described so that the primary apparatus
will actuate the distributing valve of the relay-cylinder without being positively
connected therewith.
2nd. The distributing valve of the relay-cylinder constructed and arranged
substantially as hereinbefore described so that the fluid-pressure in the valve-
casing tends to keep the said valve at the bottom of its stroke.
3rd. The combination of the rod E, the adjustable collar G, the lever F and
the valve H, substantially as, and for the purposes, above specified.
4th. The combination, with the relay-cylinder, of an air-pump, substantially as,
and for the purposes, hereinbefore described.
5th. The air-pump having its piston connected with that of the relay-cylinder
and communicating with the chamber of the primary apparatus below the
diaphragm thereof, substantially as, and for the purposes, above specified.
6th. The improved apparatus constructed substantially as described with
reference to the accompanying drawing and operating as and for the purposes
above specified.
Dated this 25th day of August. 1894
D. YOUNG & Co.,
11 & 12, Southampton Buildings, London, W.C.,
Agents for the Applicant.