Improvements in Electric Percussive Tools.
Year: 1892

page_text: Date of Application, 19th May, 1892
Complete Specification Left, 20th Mar., 1893-Accepted, 13th May, 1893
PROVISIONAL SPECIFICATION.
Improvements in Electric Percussive Tools.
I, LLEWELYN BIRCHALL ATKINSON, of Woodfield Works, Woodfield Road,
Harrow Road, in the County of Middlesex, Civil Engineer, do hereby declare the
nature of this invention to be as follows:-
This invention relates to percussive tools driven by an electric current and has
for its object the construction and arrangement of such machines whereby an
increase of effective power for a given weight and an increase of efficiency of direct
acting percussive tools is obtained.
In the Specification of British Letters Patent No. 9683 dated 21st of June 1890
granted to me, I have described a form of percussive tool designed in accordance
with the well known principles of electric motor design and applied to a motor
having a rectilinear motion; it has however been found in practice, that a difficulty
occurs in effecting the proper lamination of that part which corresponds to the
armature of a motor and also that what corresponds in a motor to back induction
and cross induction is excessive, also that the weight is large compared with the
duty capacity of the machine.
This invention overcomes these difficulties and is carried out as follows.
.
The moving part of the tool consists of a central rod on which is mounted a solid
cylinder or equivalently a number of discs of iron are threaded thereon, as used in
the construction of dynamo or motor armatures.
This moving part is carried by bearings in which it can freely reciprocate and by
rotated if desired, this part is equivalent to the moving field magnet of a motor
having a fixed armature.
Surrounding this said solid cylinder are arranged one or more laminated
magnetic cores on which are wound coils corresponding to the armature coil of a
motor.
The tool is operated by a combination of a continuous or unidirectional and an
alternating current in the manner described in the Specification of the before cited
Letters Patent 9683*0.
In this case however the continuous or unidirectional current circulates in one or
more coils partly surrounding the central cylinder and partly surrounding that part
of the magnetic circuit of the armature in which it is desired to prevent magnetic
change.
The alternating current circulates in one or more coils no longer circumferentially
surrounding the reciprocating part but wound on those parts of the armature in
which it is desired that the magnetic variation shall take place.
Dated this 10th day of May 1892
FELL & WILDING,
1, Queen Victoria Street, London, E.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Electric Percussive Tools.
I, LLEWELYN BIRCHALL ATKINSON, of Woodfield Works, Woodfield Road,
Harrow Road, in the County of Middlesex, Civil 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 :-
This invention relates to percussive tools driven by an electric current and has

page_text: for its object the construction and arrangement of such machines whereby an
increase of effective power for a given weight and an increase of efficiency of direct
acting percussive tools is obtained.
In the Specification of British Letters Patent No. 9683 dated 21st June 1890),
granted to me, I have described a form of percussive tool designed in accordance
with the well known principles of electric motor design and applied to a motor
having rectilinear motion; it has however been found in practice that a difficulty
occurs in effecting the proper lamination of that part which corresponds to the
armature of a motor and also that what corresponds in a motor to back induction
and cross induction is excessive also that the weight is large compared with the
duty capacity of the machine.
:
This invention overcomes these difficulties, and is carried out as follows;-
-:
The moving part of the tool consists of a central rod on which is mounted a solid
cylinder or equivalently a number of discs of iron are threaded thereon, as used in
the construction of dynamo or mortor armatures.
This moving part is carried by bearings in which it can freely reciprocate and be
rotated if desired, this part is equivalent to the moving field magnet of a motor
having a fixed armature.
Surrounding this said solid cylinder are arranged one or more laminated
magnetic cores, on which are wound coils corresponding to the armature coil of a
motor.
The tool is operated by a combination of a continuous or unidirectional and an
alternating current in the manner described in the Specification of the before cited
Letters Patent 9683 of 1890.
In this case however the continuous or uni-directional current circulates in one
or more coils partly surrounding the central cylinder and partly surrounding that
part of the magnetic circuit of the armature in which it is desired to prevent
magnetic charges.
The alternating current circulates in one or more coils no longer circumferentially
surrounding the reciprocating part but wound on those parts of the armature in
which it is desired that the magnetic variation shall take place.
And in order that my invention may be better understood I now proceed to
describe the same in relation to the drawings hereunto annexed reference being had
to the letters and figures marked thereon.
Fig. 1. and Fig. 2. shew in section and end elevation a reciprocating motor
constructed in accordance with the present invention, and which may be taken as a
representative form, it being understood that the number and arrangement of the
magnet poles and armature coils may be varied as in ordinary motors retaining the
principles of this present invention.
In Figs. 1. and 2. like letters refer to like parts-"a" is the central rod moving
in bearings "b."
"X" is a solid cylinder of magnetic material, or preferably build of thin discs
separated both electrically and magnetically from one another.
"C. C. are laminated magnetic cores partially surrounding the central magnetic
core, the magnet circuit being completed by the magnetic limbs "d. d. d. d" which
may be either solid or laminated.
On the magnetic cores "C. C." are wound coils "EE" which may be varied in
number and position.
The principal magnetising coils may be wound so as to surround both the central
cylinder and the laminated magnetic cores as shewn at "f.f" or may be wound on
on the magnetic limbs as "g. 9 or partly on both.
Referring now to these drawings, the coils f. f and ❝
9.9 carry a continuous or
uni-directional current magnetising the whole system in manner well understood,
the magnetic induction passing from "E to E" through the central cylinder "X."
When two coils only are wound on each laminated core as shewn, they are wound
so that the same alternating current passes through them in opposite directions, so
that when the current is in one direction, the magnetic induction from "P" to "P"

page_text: "
is neutralised, whilst that from "Q" to "Q" is strengthened with the result that
the core "X moves to "Q," when the current reverses, the opposite effect results,
producing reciprocating motion.
To prevent what in ordinary motors is known as cross induction, the parts "P.Q"
are partially or entirely separated magnetically as at "S. S" and the central cylinder
as before described is divided and separated magnetically as well as electrically.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is ;-
1. In a reciprocating motor the combination of a central rod on which are
mounted a cylinder or cylinders solid or laminated, moving longitudinally between
the faces of laminated cores, connected magnetically by limbs the whole being
magnetised by coils carrying a continuous or uni-directional current; with coils
wound round or upon the laminated cores, carrying a reversing or alternating current
or currents, as and for the purpose described.
2. In a reciprocating motor with a laminated cylinder, and laminated cores, the
separation or division of the parts magnetically to prevent cross induction as, and
for the purposes described.
3. In a reciprocating motor as described the combination of magnetising coils
wound partly or wholly round the central cylinder, and partly or wholly on the
connecting limbs with coils carrying an alternating or reversing current wound
round or upon the laminated core.
4. In a reciprocating tool the combination and arrangements of parts illustrated
and described in Figs. 1 and 2.
D
ليوم
1 1000
FELL & WILDING,
1, Queen Victoria Street, London, E.C., Agents for the Applicant.