Improvements in Variable Stroke Fluid-pressure Motors and Compressors.
Year: 1899

page_text: Date of Application, 22nd July, 1899-Accepted, 7th Oct.,
1899
COMPLETE SPECIFICATION.
Improvements in Variable Stroke Fluid-pressure Motors and
Compressors.
We, CHARLES THOMAS BROCK SANGSTER, General Manager to The Cycle Com-
ponents Manufacturing Company, Limited, of Bournbrook, near the City of
Birmingham, and CHARLES MONTAGUE LINLEY, of 42, St. Luke's Road, Clapham,
London, S.W., Manager, 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 variable stroke engines and compressors and is an
amplification or developement of the improvements in motors and compressors
described in the Specification of former Letters Patent granted to us and bearing
date the 20th day of June 1898 No. 13703, on which the variation in the length
of the piston stroke, with a corresponding differentiation in the area of the
compression chamber of the cylinder was obtained by the employment, in con-
junction with the piston rod, and intermediate between it and its connecting rod,
of a rocking beam, controlled in its movement by a radius arm and mounted
upon or swinging from a link carried by a moveable arm or frame which was
operated by suitable gearing for shifting the fulcrum of the said beam and varying
the distance between the said fulcrum and the connection of the beam to the
piston rod.
The object of the present inventions is to simplify such variable stroke engines
and compressors and to render them more efficient in action, which is effected
by reducing the number of their parts and making the construction more
compact.
Figure 1 of the accompanying drawings represents an elevation (with the
cylinder and piston in section) of a variable stroke internal combustion engine
constructed according to our present invention, according to which the piston
rod is linked to the connecting rod by a rack slide which acts as a lever and
is adjustably mounted upon a rocking carriage and is adapted, according to
its position relative to the centre about which the carriage rocks, to modify the
stroke of the piston and to give either a long stroke and large compression
area for power or a short and rapid stroke with smaller compression space for
speed as may be required, and without the employment of differential speed
gearing.
In this figure, the parts of the motor are shown in the positions which they
assume when set to give a short stroke and small compression area for rapid
driving, whilst Figure 2 represents the motor adjusted for power driving at
slow speed, with long stroke and proportionately large compression area, it
being understood that any intermediate length of stroke and area of compression
space may be obtained according to requirements.
Figure 3 represents a separate elevation of the swinging slide-carriage, which
is provided with a worm wheel and pinion gearing into a rack on the slide lever
for adjusting the latter.
Figure 4 is an end elevation of Figure 3, with the worm wheel removed.

page_text: Figure 5 is a longitudinal vertical section of the lever and its carriage,
taken through the pinion and rack.
Figure 6 is a like sectional view of the said carriage separately and Figure 7
is a transverse section of Figure 6 upon the dotted line .
Figure 8 is a side elevation of the slide lever or adjustable link between the
piston rod and connecting rod.
Figure 9 is a plan view thereof.
Figure 10 represents the worm with its stalk and hand wheel, through which
the driver controls the rack and pinion adjustment between the lever and its
bearing carriage or fulcrum and thus regulates the driving speed.
Figure 11 represents the worm wheel into which the worm, Figure 10, gears
showing its connection with the spindle carrying the pinion.
The same letters of reference indicate corresponding parts in the several
figures of the drawing.
a is a cylinder and a¹, the compression chamber at the rear end thereof, bis
the piston and e the piston rod whose outer end is jointed at c¹ to the arm or
branch of the lever or adjustable link connection d, arranged between and
adapted to communicate motion from, the said piston rode and the connecting
or driving rod e, whose outer end is jointed' at ¹, to another arm d², at the top
of the lever or link, whilst its other end e is jointed to, the crank f¹, of the
driven shaft f, which may transmit power direct at variable speeds for any
required purpose.
The sliding lever or link is carried by or is adjustable upon, a rocking carriage g,
whose opposite trunnions or journal ends g₁ work within suitable bearings h',
of the framing h, of the motor, with the slide being confined to the carriage
and guided in its movements thereon, by incline-sided grooves formed
along the inner side of the said carriage taking over guide ribs g² of a corre-
sponding section on the opposed side of the said carriage, although it is obvious
that the converse or any other suitable arrangement of guides may be employed.
Located along the inner side of the slide and preferably in a central position
between the grooves d³, is a toothed rack d', taking into a corresponding
clearance g³, between the ribs, of the carriage and engaging with a pinion i,
which extends into the said clearance and is made fast to a spindle, running
axially through the carriage and having keyed to one of its outer ends, a worm
wheel, meshing with a worm j, formed at one end of a rod j¹, which is
mounted in the framing and terminates in a hand wheel, or the like, arranged
in a position convenient for manipulation by the driver of the motor.
OPERATION.
Assuming that the engine has been running at a high speed with a short stroke
and small area of compression chamber, in which case the several parts would be
in the positions represented in Figure 1, and that the driver requires to now run
at a lower speed or with enhanced power, then by turning the hand wheel j³,
he causes the worm wheel, to rotate in the direction indicated by the arrow
in Figure 1 and carry round with it the pinion i, which, by meshing with the
rack, causes the sliding intermediate lever d, to descend until it reaches a
position such for instance as is shown in Figure 2. This has the effect of
increasing the distance between the point c¹ at which the piston rod and lever
are connected and the bearings g', of the carriage which constitute the fulcrum
whereon the said rocking carriage and lever swing, whilst the distance between
the point c', where the connecting rod is jointed to the said lever and the said
fulcrum is correspondingly decreased. It therefore follows that, whereas when
the parts were in the previous position (Figure 1) the short stroke of the piston
was multiplied to the connecting rod, a much longer piston stroke is now
obtained but its movement is reduced or speeded down in being transmitted by
the intermediate rocking lever member to the connecting rod, whose stroke is
always constant.

page_text: It is understood that the levering member may be shifted to any intermediate
position between those shown respectively in Figures 1 and 2, whereby corre-
sponding variations of speed may be obtained and that instead of employing a
rack and pinion for shifting the position of the rocking lever or swinging link
member relative to its fulcrum, we may use any other mechanism which will
give the desired movement to the slide. Further instead of operating the adjust-
ment mechanism by a worm and worm wheel as described, we may employ any
other gearing which will convey the required movement and retain the parts in
their proper positions after the adjustment has been accomplished.
The application of our invention to compressors for various purposes differs in
no essential respect from its application to internal combustion engines as herein
described.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that
what we claim is:
First: In variable stroke motors, the employment in conjunction with the
piston rod, and intermediate between it and its connecting rod, of a rocking
slide link or lever which is adjustable relative to a stationary fulcrum or centre
of motion, whereby the distance between the point of connection of the piston
rod with the said lever and the said fulcrum may be varied substantially as
and for the purpose described and set forth.
Secondly-In variable stroke motors, the employment in conjunction with
the piston rod and intermediate between it and its connecting rod, of a lever or
link, mounted upon a carriage or bearing which is free to rock about a stationary
fulcrum and upon which the said lever member is adjusted or made to slide by
rack and pinion gearing, substantially as and for the purpose described and set
forth.
Thirdly: A variable stroke motor comprising a cylinder with piston and
piston rod, jointed to an intermediate lever or rocking member arranged between
the said piston rod and the connecting rod which drives the crank shaft, with the
said lever being mounted upon a rock carriage having trunnions or journal ends
working in bearings and constituting the stationary fulcrum of the lever, which
is made to slide for adjusting or shifting it relative to the said fulcrum by a rack
upon it being engaged by a pinion mounted on a spindle directed through the
carriage and provided with a worm wheel which is rotated through a worm and
hand wheel, the several parts being arranged, combined and operated substantially
as and for the purpose herein described and set forth.
Fourthly: In variable stroke motors and air compressors, the employment
of means arranged and operating to vary the length of piston or plunger stroke
substantially as herein described and set forth.
1030
CHARLES THOMAS BROCK SANGSTER,
CHARLES MONTAGUE LINLEY,
By Henry Skerrett,
24, Temple Row, Birmingham, Agent for Applicants.