Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02701446 2010-04-26
ELECTRO-MECHANICAL FIREARM TRIGGER MECHANISM
FIELD OF THE INVENTION
Embodiments of the invention relate generally to firearms. More particularly,
embodiments of the invention relate to an electro-mechanical trigger mechanism
for an
automatic firearm.
BACKGROUND OF THE INVENTION
It is known that firearms that have purely mechanical automatic trigger
mechanisms, such as the type disclosed in U.S. Patent No. 3,045,555 to Stoner,
can
operate with excessively high firing rates in an automatic firing mode. MI6
type firearms
using purely mechanical automatic trigger mechanisms can have rates of fire
well in
excess of 600 rounds per minute, particularly in models with shorter barrels.
These high
rates of fire may be problematic, as they can, among other things, affect the
control and
accuracy of the firearm, increase the accumulation of heat in the barrel, or
result in
unnecessary wastage of ammunition.
High rates of fire affect the control and accuracy of the firearm due to
muzzle
climb, as there is insufficient time between consecutive discharges to allow
the operator to
return the firearm to its original point of aim. This is compounded by a
desire to increase
the portability and maneuverability of firearms by reducing weight and size,
which
respectively contribute to decreased stability and further increased rates of
fire.
In addition, the accumulation of heat in the barrel may contribute to erosion
and
wear in the barrel, and can further impact the accuracy of the firearm.
It is, therefore, desirable to provide an electro-mechanical trigger mechanism
for
an, automatic firearm to provide a controlled rate of fire when the firearm is
operated in an
automatic firing mode.
SUMMARY OF THE INVENTION
In a first aspect, there is provided an electro-mechanical trigger mechanism
for
controlling automatic firing of a firearm, the electro mechanical trigger
mechanism
comprising a solenoid operatively connected to a sear disconnect of the
firearm; and a
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processor, for controlling the solenoid; wherein, based on inputs to the
processor, the
processor controls a flow of current to the solenoid to control the automatic
firing of the
firearm.
In a further aspect, there is provided a method of controlling, an automatic
firing mode
for a firearm by controlling a rate of fire using an electro-mechanical
trigger mechanism
comprising determining that the firearm is in the automatic firing mode; and
supplying a flow
of current to a solenoid to control the rate of fire via a sear disconnect
connected to the
solenoid.
In another aspect, there is provided an electro-mechanical trigger mechanism
for
controlling automatic firing of a firearm, the electro mechanical trigger
mechanism
comprising a firing mode selector for placing the firearm in an automatic
firing mode and a
semi-automatic firing mode; a solenoid operatively connected to a sear
disconnect of the
firearm; a processor operatively coupled to the solenoid, wherein the
processor actuates the
solenoid when a trigger of the electro-mechanical trigger mechanism is
actuated and the
firearm is in the automatic firing mode; and wherein the solenoid is not
actuated when the
trigger of the electro-mechanical trigger mechanism is actuated and the
firearm is in the semi-
automatic firing mode.
In yet another aspect, there is provided an electro-mechanical trigger
mechanism for a
firearm, the electro mechanical trigger mechanism being capable of operating
in an automatic
firing mode and a semi-automatic firing mode; a firing mode selector for
placing the firearm
in the automatic firing mode and the semi-automatic firing mode; a solenoid
for use only in
the automatic firing mode, the solenoid being operatively connected to a sear
disconnect of
the firearm; a processor operatively coupled to the solenoid, wherein the
processor actuates
the solenoid when a trigger of the electro-mechanical trigger mechanism is
actuated and the
firearm is in the automatic firing mode; and wherein the solenoid is not
actuated when the
trigger of the electro-mechanical trigger mechanism is actuated and the
firearm is in the semi-
automatic firing mode.
In a further aspect, there is provided an electro-mechanical trigger mechanism
for
controlling automatic firing of a firearm, the electro mechanical trigger
mechanism
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comprising a firing mode selector for placing the firearm in an automatic
firing mode and a
semi-automatic firing mode; a mechanism operatively connected to a sear
disconnect of the
firearm; a means for controlling operation of the mechanism and for sensing
the position of
the firing mode selector and for sensing actuation of the trigger, wherein the
means actuates
the mechanism when a trigger of the electro-mechanical trigger mechanism is
actuated and
the firearm is in the automatic firing mode; and wherein the mechanism is not
actuated when
the trigger of the electro-mechanical trigger mechanism is actuated and the
firearm is in the
semi-automatic firing mode.
In yet another aspect, there is provided a method of controlling an automatic
firing
mode for a firearm by controlling a rate of fire using an electro-mechanical
trigger mechanism
eomprising determining that the firearm is in the automatic firing mode; and
supplying a flow
of current to a solenoid to control the rate of fire via a sear disconnect
connected to the
solenoid.
In still another aspect, there is provided a method of controlling the rate of
fire of a
firearm, comprising sensing the position of a firing mode selector configured
for placing the
firearm in an automatic firing mode and a semi-automatic firing mode; sensing
the position of
a trigger of the firearm; and actuating a mechanism operatively connected to a
sear disconnect
of the firearm when the trigger of the electro-mechanical trigger mechanism is
actuated and
the firearm is in the semi-automatic firing mode.
In another aspect, there is provided a firearm, comprising a barrel; an
electro-
mechanical trigger mechanism for controlling automatic firing of the firearm,
the electro
mechanical trigger mechanism including a firing mode selector for placing the
firearm in an
automatic firing mode and a semi-automatic firing mode; a mechanism
operatively connected
to a sear disconnect of the firearm; a means for controlling operation of the
mechanism,
wherein the means actuates the mechanism when a trigger of the electro-
mechanical trigger
mechanism is actuated and the firearm is in the automatic firing mode; and
wherein the
mechanism is not actuated when the trigger of the electro-mechanical trigger
mechanism is
actuated and the firearm is in the semi-automatic firing mode.
Other aspects and features of embodiments will become apparent to those
ordinarily
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skilled in the art upon review of the following description of specific
embodiments of the
invention in conjunction with the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the invention will now be described, by way of example only,
with
reference to the attached Figures, wherein:
Fig. 1 is a cross-sectional view of a portion of a firearm incorporating an
electro-
mechanical trigger mechanism; and
Fig. 2 is a flow chart of a method of using an electro-mechanical trigger
mechanism
for controlling a firearm.
DETAILED DESCRIPTION
In this disclosure, an embodiment of an electro-mechanical trigger mechanism
and a
method for using Such a mechanism to control a firearm are disclosed.
Embodiments of the
invention may be applied to a wide variety of firearms, but is shown here in
an embodiment
with an automatic firearm, such as an AR-15, MI6 or U.S. Patent No. 3,045,555
(Stoner)
type.
Figure 1 shows a first cross sectional view of a firearm 10 incorporating an
electro-
mechanical trigger mechanism. In one embodiment the electro-mechanical trigger
mechanism
40 resides within a hand grip 12.
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The electro-mechanical trigger mechanism 40 comprises a solenoid 26 which is
in
communication with, and controlled by, a processor 28, such as a central
processing unit
(CPU) and is also connected to a hammer 20 and a trigger 22 via a sear
disconnect 24.
A firing mode selector 14 provides an apparatus for switching operation of the
firearm 10 between a safe mode, a semi-automatic mode, and an automatic mode
as
determined, or required, by a user of the firearm 10.
The solenoid 26 is also connected to a plunger 32 which extends between the
solenoid 26 and the sear disconnect 24. In one embodiment, the solenoid
plunger 32 can
be biased towards the sear disconnect 24 by a coil spring or an elastic
member.
The hammer 20 includes a primary sear abutment 56 and a secondary sear
abutment 54, and is pivotally mounted by a transversely oriented pivot pin 35.
The sear disconnect 24 includes a secondary sear 46 and is moveable between a
catch position and a release position. In the catch position the secondary
sear 46 engages
the secondary sear abutment 54 and the hammer 20 is held in a cocked position.
In the
release position the secondary sear 46 is pivoted such that the secondary sear
46
disengages the secondary sear abutment 54 so that the hammer 20 is not
retained by the
secondary sear 46.
The sear disconnect 24 further includes a slotted opening 42 operative with
pin 44
connected to the solenoid plunger 32. This configuration connects the sear
disconnect 24
and the solenoid 26. In use, this configuration allows the solenoid 26 to
engage the sear
disconnect 24, thus releasing it from the secondary sear 46 and allowing for
automatic
firing, when necessary.
The CPU 28 is operatively connected to a power source, in the form of a
battery
48, a trigger sensor 50 which is used for sensing whether or not the trigger
22 is pulled, a
firing mode sensor 52 which is used for sensing the position of the firing
mode selector 14
and a timer 55 which is used to determine the rate of fire by the firearm 10.
It will be
understood that the location of the CPU 28, the battery 48, the trigger sensor
50, the firing
mode sensor 52 and the timer 55 may be anywhere within the firearm 10 and not
simply at
the locations outlined in Figure 1. In operation, the CPU 28 controls the
supply of current
from the battery 48 to the solenoid 26, and includes circuitry or software
instructions to
apply a current pulse to the solenoid 26 for a pre-determined number of times,
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corresponding to a number of rounds to be fired to provide a burst fire mode.
This is
based on inputs which are received by the processor 28 from the various
sensors located
throughout the firearm 10. Furthermore, a temperature sensor 58 is located
within a barrel
57 of the firearm to provide temperature information to the CPU 28 so that the
CPU can
control the solenoid 26 based on this information. In alternative embodiments,
the CPU
28 can receive other information which can assist in controlling the solenoid
26. This other
information can be in the form of a user input or could be information which
is received
from a firearm sighting system.
In semi-automatic operation of the firearm, the firing mode selector 14 is set
to
semi-automatic and the electro-mechanical trigger mechanism 40 operates in a
purely
mechanical manner whereby the solenoid 26 is not used. In this situation, the
CPU 28 may
not be fully powered in order to conserve the battery 48. When the firing mode
sensor 52
transmits a signal to the processor that the semi-automatic mode has been
selected, the
processor does not allow current to be supplied to the solenoid 26.
In order to initiate the semi-automatic firing mode, the hammer 20 is cocked
either
from a previous use or through the user physically pulling back the bolt (not
shown). The
hammer 20 is held by the engagement between the primary sear abutment 56 and
the
primary sear 36.
When the trigger 22 is pulled, the hammer 20 is released, and engages a firing
pin
(not shown) to fire a round from the firearm and to cock the hammer 20, which
is caught
and held by the engagement of the secondary sear abutment 54 and the secondary
sear 46.
When the trigger 22 is released, the secondary sear 46 is released, but the
hammer
20 remains cocked by the engagement of the primary sear abutment 36 and the
primary
sear 56 and this completes one cycle of ammunition firing in the semi-
automatic firing
mode.
In automatic firing mode operation of the firearm, the firing mode selector 14
is set
to automatic and the electro-mechanical trigger mechanism 10 operates in an
electro-
mechanical manner. The CPU 28 may be activated by the firing mode sensor 52
which
transmits a signal to the CPU 28 indicating that the firing mode selector 14
has been set to
automatic and the CPU 28 provides current to the solenoid 26 to control the
firing of the
firearm.
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In order to initiate the automatic firing mode, the hammer 20 is cocked either
from
previous use or by physically pulling back the bolt to cock the hammer 20. The
hammer
20 is held by the engagement of the primary sear abutment 56 and the primary
sear 36.
When the trigger 22 is pulled, the hammer 20 is released, and engages a firing
pin
to fire a round from the firearm and cock the hammer 20, which is caught and
held by the
engagement of the secondary sear abutment 54 and the secondary sear 46.
However, unlike semi-automatic mode, if the firing mode selector 14 is set to
automatic and the trigger 22 is held in place, the CPU 28 provides current to
cycle the
solenoid 26 in accordance with a selected control methodology. Therefore, the
CPU
continues to control the necessary current to the solenoid 26 so that the
firearm can
continue to operate in the automatic firing mode. The trigger sensor 50
detects whether
the trigger is pulled or released and provides that information to the CPU 28
so that the
CPU recognizes that the solenoid 26 is to continually receive current to
assist in
controlling the firing rate of the firearm in that the CPU can control the
flow of current to
the solenoid 26 which directly affects the firing rate, or rate of fire
In one embodiment, the control methodology may include setting or limiting a
rate
of fire based on signals received from the timer 55, the barrel temperature
sensor 58 or
both. As long as the trigger 22 (detected by the trigger sensor 50) is held in
place, the
CPU 28 will operate the solenoid 26 to trip the sear disconnect 24 causing the
secondary
sear 46 to release the hammer 20, and continuously engage the firing pin to
fire a round
from the firearm and re-cock the hammer 20. The hammer 20 is caught and held
by the
engagement of the secondary sear abutment 54 and the secondary sear 46, until
the
solenoid 26 cycles or the trigger 22 is released. If the trigger 22 remains
held, the solenoid
26 cycles again allowing another round to be fired.
When the trigger 22 is released, the hammer 20 is caught by the engagement of
the
primary sear abutment 56 and the primary sear 36 and held in the cocked
position, and this
competes one cycle of operation in automatic mode. In one embodiment, once the
trigger
sensor senses release of the trigger, a signal is transmitted to the processor
to stop the flow
of current to deactivate the solenoid.
Referring now to Figure 2 a flow chart of a method for use of an electro-
mechanical trigger mechanism in controlling a firearm is shown generally as
100.
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Although this is shown as a sequential process, one skilled in the art will
recognize that
many of the steps may run in parallel and interrupt the stream to provide
data, examples
being at steps 114, 116 and 120.
Beginning at step 102, a test is made by the processor 28 to determine the
position
or status of the firing mode selector 14. In one embodiment, this can be
performed by
having the processor 28 communicating with or accessing the firing mode sensor
52 to
retrieve the mode selector information. At step 104, a test is made to
determine if the
safety of the firearm is on or if the firing mode selector has been set to
safe mode. If the
safety is on or the firing mode selector 14 is set to safe mode, the firearm
is unable to fire
(step 106) and processing returns back to step 102 to monitor the firing mode
selected by
the firing mode selector. At step 108, a test is made to determine if the
firing mode
selector is set at semi-automatic by having the processor communicate with the
firing
mode sensor. If so the firearm is considered active and may operate in semi-
automatic
mode until the status or position of the selector 14 is changed. This is
continually checked
in step 102. Should the test at step 108 indicate that the firearm is not semi-
automatic,
then it is fully automatic as can be confirmed by the processor and processing
moves to
step 114. As discussed above, the processor continually checks the firing mode
sensor to
determine the selected firing mode. At step 114 a test is made to determine or
control the
rate of fire. In one embodiment, the CPU 28 obtains data from timer 55 which
provides
data on how quickly the firearm is discharging rounds. Processing then moves
to step 116
where the barrel temperature is tested by barrel temperature sensor 58. The
barrel
temperature is then transmitted to the processor so that the processor can
further control
the rate of fire, if necessary. At step 118, if the barrel temperature is
within an acceptable
range for the firearm, processing moves to step 122 where a test is made to
determine if
the trigger 22 has been released by having the processor communicate with the
trigger
sensor, otherwise the firearm can continue to be used in automatic mode and
the
temperature of the barrel continued to be monitored (step 116). If the
temperature is
determined to be too hot, in one embodiment, the CPU can lower the rate of
fire to reduce
the amount of heat generated by controlling the current flow being supplied to
the
solenoid. In another embodiment, a signal may be transmitted from the CPU
processor to
the solenoid to power down the solenoid so that the firearm returns to the
release position
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and therefore no longer in the automatic firing mode. At step 122, if the
trigger has been
released, processing returns to step 102 until the firearm is be used again.
While in automatic firing mode, steps 116, 118 and 122 can be cycled to
determine
if automatic firing should be disabled or the rate of fire reduced due to
temperature (step
118) or by the release of the trigger (step 122).
In the preceding description, for purposes of explanation, numerous details
are set
forth in order to provide a thorough understanding of the embodiments of the
invention.
However, it will be apparent to one skilled in the art that these specific
details are not
required in order to practice the invention. In other instances, well-known
electrical
structures and circuits are shown in block diagram form in order not to
obscure the
invention.
The above-described embodiments of the invention are intended to be examples
only. Alterations, modifications and variations can be effected to the
particular
embodiments by those of skill in the art without departing from the scope of
the invention,
which is defined solely by the claims appended hereto.
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