Improvements in Motors for Tools, Stamps, and the like Reciprocating Mechanism.
Year: 1899

page_text: Date of Application, 17th Nov., 1899-Accepted, 24th Feb., 1900
COMPLETE SPECIFICATION.
Improvements in Motors for Tools, Stamps, and the like Reciprocating
Mechanism.
I, CHESTER BIDWELL ALBREE, of 187, Western Avenue, Allegheny, in the
County of Allegheny, State of Pennsylvania, United States of America,
Mechanical 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, reference being had to the
accompanying drawings in which:-
Figure 1 is a longitudinal section of a pneumatic tool embodying my inven-
tion. Figure 2 shows the same with the parts in the positions which they
occupy when the piston is at the other end of its stroke. Figure 3 illustrates
a modification, and Figures 4 and 5 are like views of other modifications.
My invention relates to the class of pneumatic tools, rock-drills, hammers,
stamps, and other mechanism of the reciprocatory type, and is designed to
provide a compound motor of improved construction wherein the motive fluid
acts at high pressure to move the piston in one direction, and then expansively
at a lower pressure to move the piston in the opposite direction, thus imparting
great efficiency to the motor and enabling it to be used with economy of motive
fluid.
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In the form shown in Figs. 1 and 2 of the drawing, A represents the cylinder,
having two portions A, A' of different diameter, and B is the inlet port opening
into the larger portion A of the cylinder. D) is the exhaust-port communicating
with an annular space C in the smaller diameter of the cylinder. The piston E
has two portions E and E of different diameters, fitting respectively within
the portions A, A' of the cylinder, and around the larger portion E is an
annular recess of sufficient length to constitute a port which is always in
communication with the inlet-port B in every position of the stroke of the piston.
It will be understood that the shape of the ports B and F, may be reversed,
the port B being elongated, and the port F being a single opening,
is
same
between
the relations
and L,
the ports G
hereinafter described. G is a passage which is formed lengthwise
the annular
through the piston, having ports H communicating with
port F, and ports L communicating with an annular port C adapted by reason
of its length to be in communication with the ports L at every portion of the
stroke of the piston. Ports J also lead from the passage G to the outer surface
of the piston at or near the shoulder K at the junction of the large and small
diameters of the piston. The passage G is preferably cylindrical, and it contains
a hollow sliding inertia-valve M which fits neatly therein, but is free to slide
back and forth. It has an exterior annular recess N, constituting a port of
sufficient length to register with and connect the ports H and J when the valve
is at the outer end of the passage G, as shown in Fig. 1. It has also a port O
leading from the interior to the exterior of the valve, and adapted to register
with the ports J when the valve is at the inner end of the passage G, as
illustrated in Fig. 2. The valve has ports P, leading from its interior to its
exterior surface, and adapted to register with the ports L when the valve is at
the outer end of the passage G, as shown in Fig. 1. The valve has also an

page_text: exterior annular space Q, so situate that it does not register with any two of
the ports, L, J or H at any position of the valve. Therefore it does not serve
as a port, but its purpose is to contain coiled springs S, S¹, the adjacent ends
of which bear against a ring R, which is fixed to the interior of the passage G,
of the piston. The outer ends of the springs bear against the valve at the ends
of the annular space Q, and these springs are so related to each other in strength,
that normally they hold the valve in the position shown in Fig. 1 but they are
sufficiently flexible to allow the valve to be moved by inertia to the other end
of its stroke, in the manner explained below. The piston has a socket or
holder T adapted to the tool which is intended to be used with it, and the
cylinder has a suitable head V. At the end of the passage G is a stop U
adapted to limit the motion of the valve, and between the cylinder head and
the piston is a spring W, which is adapted to return the piston automatically
to the outer end of the stroke when the cylinder is disconnected from power, in
order to put the parts in position for starting as explained below.
.
The operation is as follows: The parts being in the position shown in Fig. 1,
to start the motor, compressed air is admitted through the port B, and thence
passes through the passage F, and ports H; passage N, and ports J to the
shoulder or differential area K on the piston, and forces the piston to the rear
end of the cylinder, the air contained in the rear portion of the cylinder being
displaced through the passage G, hollow valve M, ports P and L, and passage C
to the exhaust port. When the piston strikes the rear end of the cylinder, its
motion is checked thereby, and the valve M by reason of its inertia moves back
in the passage G until it is stopped by the stop U. The parts then are in the
position shown in Fig. 2, in which the inlet ports B and H are cut off from com-
munication with the working space of the cylinder, and the space A² of the
cylinder at the shoulder K is put into communication with the rear of the
cylinder by the way of the ports J, O and hollow valve passage M, the exhaust
ports being cut off from communication with the interior of the valve by the
disconnection of the ports L and P. Thereupon the air under the pressure
which is contained in the space A flows to the rear end of the piston, and by
reason of its expansion forces the piston outward, the air pressure per square
inch decreasing as the motion of the piston continues and as the volunie of
the space in which the motive fluid can expand increases. When the forward
motion of the piston is checked, either by striking the end of the cylinder,
or by striking of the tool against some object before the end of the stroke is
reached, the valve M. continues to move by reason of its inertia until it reaches
the end of the passage G, whereupon the valve is brought again into the position
shown in Fig. 1, another supply of motive fluid is admitted from the inlet 13
into the space A2 and any motive fluid remaining under pressure at the back
end of the piston exhausts through the ports P, L and D, the motion of the
piston being thus reversed, and the operation repeated, as above described.
In order to insure the starting of the piston, it is necessary that the passage N
should be in register with the ports and H and also that the piston should be
at the outer end of its stroke. This is not always the position of the parts when
the motive fluid is cut off, and if the apparatus should come to rest with the
piston at the rear end of its stroke, it must be moved to the other end in order
to make it possible to start the apparatus. Great convenience is effected by
doing this automatically, and although such automatic means are not essential
to my invention, broadly considered, the means which I have invented for that
purpose are desirable and I intend to claim the same.
The necessary automatic motion of the valve to its outer position, is effected
by the springs S S₁ which may be either in tension or compression, and which
as above explained, normally hold the valve in the position of Fig. 1. The
spring W, when the motive fluid is turned off, presses the piston automatically
to the outer end of its stroke so that no matter at what portion of the stroke the
piston may be stopped, it will immediately assume the position required for

page_text: starting. When the cylinder is vertical or nearly so, with the piston extending
downwardly, this spring is not necessary, for the automatic return of the piston
will be effected by gravity.
The arrangement of the ports and passages shown in Figs. 1 and 2 may be
varied, or more than one inertia valve may be employed, without departure from
the scope of my invention. For example, the parts may be arranged so that
the motive fluid will act at high pressure to move the piston outwardly, and
will perform the backward stroke by expansion.
The springs controlling the valve M may be placed inside of the valve, or
at its ends, or may be otherwise arranged to perform the function above explained.
In Fig. 3, I show a motor working on the same principle as in Fig. 1, but
with the position of the ports varied the port B being in the smaller portion of
the cylinder and the port D in the larger portion and the port O being formed
in the piston. The operation of this form of my invention will be sufficiently
apparent from the drawing without further description, the same reference letters
being used as in Fig. 1 to designate the parts.
In Fig. 4 I show a form of my device in which the direct pressure is employed
to force the piston outwardly, while the reverse stroke is accomplished by ex-
pansion of the motive fluid admitted on the out-stroke. In this form the piston
has three diameters, the portion E2 at its rear end extending outwardly through
the cylinder, and an annular stop X being provided to engage the part E and
to limit the instroke of the piston. In the operation of this form of my
invention, the compresed air passes from the port B through passage F, port H,
passage N, and port 5 into the space between the parts E and E of the piston
and propels the piston forward, the air in advance of the part E being displaced
through ports J, O, L, and passage C through the exhaust D. When the piston
is checked the valve moves forward by inertia, thus shutting off the exhaust and
inlet and connecting the space back of the piston part E with the space in front
of said part by way of a port 6, hollow valve passage, and ports 7 and J. The
compressed air in the cylinder then expands into this space in front of the piston
and drives the piston back, until at the end of its back stroke the valve is
moved by inertia into the position shown in Fig. 4.
In Fig. 5 I show an arrangement which is similar to Fig. 1, except that two
inertia valves M₁ M² are employed. A plug G' separates these valves and forms
the rearward stop for the valve M. Air enters the inlet port B, traverses the
passage F, port H, port 2, into the interior of the hollow inertia valve M, and
thence through said valve and through a port 3 to a space back of the shoulder K
between the two diameters of the piston, thus moving the piston rearwardly.
When the piston reaches the end of its stroke, the valves M M² are moved back
by inertia, thus closing the port H and cutting off the air-supply, and putting
the space A2 of the cylinder into communication with the space back of the
piston by way of a port 4 which is uncovered by backward motion of the
valve M², the exhaust ports L and L being cut off from communication with
the space back of the piston by the same rearward motion of this valve. The
piston is then propelled forwardly and when its motion is checked the inertia
valves are again brought into the position shown in Fig. 5, and the operations
above described are repeated.
The efficiency of the apparatus will be appreciated by those skilled in the
art. The operation of the valves is automatic, the construction is simple, and
by reason of the compound action of the motor, the motive fluid received at
high pressure can be exhausted at very low pressure, and great economy thus
obtained.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:
amusund motor having
nistan
th differential

page_text: valves carried thereby and adapted to move by inertia when the motion of the:
piston is checked, and a port or ports affording communication between the
space at the small area of the piston and the space at the larger area thereof
said valve or valves being arranged to open said communication at the time
when the said port is cut off from the source of motive fluid, whereby a high-
pressure motive fluid is admitted to press on the smaller area of the piston at
one end of the travel of the valve, and whereby the same motive fluid is admitted
to press on the larger area of the piston when the piston and valve are checked
in their travel at or near the opposite end; substantially as described.
2. A motor having a piston, a valve carried thereby and adapted to move by
inertia to control the ports, and a spring bearing on the valve and adapted to
restore it to starting position when the motor is stopped, substantially as
described.
3. A compound motor having a piston with differential areas, a valve or
valves carried thereby and adapted to move by inertia when the motion of the
piston is checked, and ports controlled by said valves, whereby a high pressure
motive fluid is admitted to press on the smaller area of the piston at one end
of the travel of the valve, and whereby the same fluid is admitted to press on
the larger area of the piston when the piston and valve are checked in their
travel at or near the opposite end, said valve having a spring adapted to hold
such valve at or normally near the end portion of its travel in position to
admit motive fluid to the smaller piston area when the piston is at rest;
substantially as described.
4. A motor, comprising a cylinder having portions of different diameters, a
piston within the cylinder and having corresponding portions of different dia-
imeter, a valve carried by the piston and arranged to move by inertia when the
piston is checked and a spring acting upon the piston and adapted to move
toward the smaller portion of the cylinder when the motor is stopped, to restore
the parts to starting position; substantially as described.
5. A motor having a reciprocating piston with differential areas upon which
the motive fluid acts in opposite direction respectively, one of said areas adapted
to receive such fluid at high pressure and the other to receive the same ex-
pansively, a valve adapted to be moved by inertia when the motion of the piston
is checked, ports controlled by the motion of the valve and adapted to successively
admit fluid at high pressure to one of said areas and afterwards to admit the
same fluid to act expansively on the other piston area, and an inlet port for
such fluid adapted to be opened by said valve when it moves to admit the fluid
at high pressure and to be closed thereby when it moves to admit the fluid
expansively to the other piston area, and an exhaust port also controlled by such
valve and adapted to be opened thereby during direct action of the motive fluid
and to be closed during its expansion; substantially as described.
6. A motor having a reciprocating piston with differential areas upon which
the motive fluid acts in opposite directions respectively, one of said areas adapted
to receive such fluid at high pressure and the other to receive the same expan-
sively, a valve adapted to be moved by inertia when the motion of the piston
is checked, and ports controlled by the motion of the valve and adapted to
successively admit fluid at high pressure to one of said areas and afterwards
to admit the same fluid to act expansively on the other piston area, said valve
being hollow and having ports formed in and through its side; substantially as
described.
11
1
1
1
1000
W. B. JOHNSON,
4, Clayton Square, Liverpool, Agent.