[0001] This application relates to a power tool, such as a drywall screwdriver, with an
ergonomic handgrip.
[0002] Various drywall screwdrivers with handgrips are known in the art. However, the handgrips
of these known screwdrivers are lacking in ergonomic design, resulting in user discomfort
and fatigue when the tool is used over a period of time.
[0003] In an aspect, a power tool with an ergonomic handgrip includes a housing with a rear
end portion, a front end portion, and lateral sidewalls, and defining a tool axis.
A motor is disposed in the housing. A working end is coupled to the front end portion
of the housing, and configured to be driven by the motor. A handle has a proximal
portion coupled to the housing, a distal end portion away from the housing, a rear
wall portion, and a front wall portion, and defines a handle axis. A trigger is coupled
to the handle and defines a trigger axis extending in a direction of trigger movement.
A first gripping region includes a rear concave recess on the rear end portion of
the housing and a lateral concave recess extending along one of the lateral sidewalls
of the housing generally parallel to the tool axis. The rear concave recess has an
innermost point that is closest to the front end portion of the housing. A second
gripping region includes a convex surface on the rear wall portion of the proximal
portion of the handle. A vertical line extending from the innermost point generally
perpendicular to the tool axis intersects the trigger axis at a first intersection
point that is forward of a second intersection point where the trigger axis intersects
the handle axis.
[0004] Implementations of this aspect may include one or more of the following features.
A third gripping region may be disposed on the housing, and offset rearward of the
front end portion of the housing. The trigger axis may be generally perpendicular
to the handle axis. The trigger axis may be at an acute angle of at least 15 degrees
to the tool axis. The convex surface may have a curvature defined by an ellipse that
has an eccentricity of less than 0.5. The ellipse may have a center proximate to the
trigger axis. The ellipse may have a minor axis generally parallel to the tool axis
and a major axis generally perpendicular to the tool axis. The convex surface may
have a rearmost point that is approximately 26 mm to 32 mm rearward of the innermost
point and approximately 70 mm to 80 mm distal of the innermost point. A fourth gripping
surface may be on the rear wall portion of the distal portion of the handle extending
along the handle to a point distal of the trigger. The ergonomic handgrip may be configured
to be grasped in one of: (a) a first grip position where the first gripping region
receives a thumb and a forefinger of a user, the second gripping region receives in
a palm of the user, and the trigger receives at least one of a ring finger and a pinky
finger of the user; and (b) a second grip position where the second gripping portion
receives the thumb of the user, the trigger receives at least one of the forefinger
and the middle finger of the user, and the fourth gripping region receives the palm
of the user.
[0005] In another aspect, a power tool with an ergonomic handgrip includes a housing with
a rear end portion, a front end portion, and lateral sidewalls, and defines a tool
axis. A motor is disposed in the housing. A working end is coupled to the front end
portion of the housing, and configured to be driven by the motor. A handle has a proximal
portion coupled to the housing, a distal end portion away from the housing, a rear
wall portion, and a front wall portion, and defines a handle axis. A trigger is coupled
to the handle and defines a trigger axis extending in a direction of trigger movement.
A first gripping region includes a rear concave recess on the rear end portion of
the housing and a lateral concave recess extending along one of the lateral sidewalls
of the housing generally parallel to the tool axis. A second gripping region includes
a convex surface on the rear wall portion of the proximal portion of the handle. The
convex surface has a curvature defined by an ellipse that with an eccentricity of
less than 0.5.
[0006] Implementations of this aspect may include one or more of the following features.
The trigger axis may be generally perpendicular to the handle axis. The trigger axis
may be at an acute angle of at least 15 degrees to the tool axis. The ellipse may
have a center proximate to the trigger axis. The ellipse may have a minor axis generally
parallel to the tool axis and a major axis generally perpendicular to the tool axis.
The rear concave recess may have an innermost point that is closest to the front end
portion of the housing, and the convex surface may have a rearmost point that is approximately
26 mm to 32 mm rearward of the innermost point and approximately 70 mm to 80 mm distal
of the innermost point. A fourth gripping surface may be on the rear wall portion
of the distal portion of the handle extending along the handle to a point distal of
the trigger. The ergonomic handgrip may be configured to be grasped in one of: (a)
a first grip position where the first gripping region receives a thumb and a forefinger
of a user, the second gripping region receives in a palm of the user, and the trigger
receives a ring finger of the user; and (b) a second grip position where the second
gripping portion receives the thumb of the user, the trigger receives the forefinger
of the user, and the fourth gripping region receives the palm of the user.
[0007] In another aspect, a power tool with an ergonomic handgrip includes a housing with
a rear end portion, a first front end portion, a second front end portion, and lateral
sidewalls, and defines a tool axis. A motor is disposed in the housing. A working
end is coupled to the front end portion of the housing, and configured to be driven
by the motor. A handle includes a proximal portion is coupled to the housing, a distal
end portion away from the housing, a rear wall portion, a front wall portion, and
a pair of sidewalls, and defines a handle axis. A trigger is coupled to the handle
and defines a trigger axis extending in a direction of trigger movement. A first gripping
region includes a rear concave recess on the rear end portion of the housing and a
lateral concave recess extending along one of the lateral sidewalls of the housing
generally parallel to the tool axis. A second gripping region includes a convex surface
on the rear wall portion of the proximal portion of the handle. A third gripping region
is on the second front end portion of the housing and is offset rearward from first
front end portion. A fourth gripping region is on the rear end portion of the distal
portion of the handle. A fifth gripping region is on the front wall portion of the
distal portion of handle adjacent the trigger. A sixth gripping region is on the front
wall portion of the distal portion of the handle, distal of the fifth gripping region.
The handle has a first depth from the trigger to the convex gripping surface, a second
depth from the fifth gripping region to the fourth gripping region, and a third depth
from the sixth gripping region to the fourth gripping region, the first depth being
greater than the second depth, and the second depth being greater than the third depth.
The handle has a first width between the sidewalls at the trigger, a second width
between the sidewalls at the fifth gripping region, and a third width between the
sidewalls at the sixth gripping region, the first width being less than the second
width, and the second width being approximately equal to the third width.
[0008] Implementations of this aspect may include one or more of the following features.
The gripping regions may be configured to be grasped in one of: (a) a first grip position
where the lateral concave recesses receives a thumb and a forefinger of a user, the
rear concave recess receives a web between the thumb and the forefinger of the user,
the convex gripping surface is received in a palm of the user, the third gripping
region receives a middle finger of the user, and the trigger receives at least one
of a ring finger and a pinky finger of the user; and (b) a second grip position where
the fourth gripping region receives the palm of the user, the convex gripping surface
receives the web and the thumb of the user, the fifth gripping region receives the
ring finger of the user, the sixth gripping region receives the pinky finger of the
user, and the trigger receives at least one of the forefinger and the middle finger
of the user. A trigger lock-on switch may be on the fifth gripping region.
[0009] Advantages may include one or more of the following. First, the position of the innermost
point of the first gripping region relative to the trigger axis and the handle axis
results allows the web between the user's thumb and forefinger to lie closer to the
trigger, resulting in a more ergonomic grip and easier actuation of the trigger. Second,
the position and low eccentricity of the ellipse defining the second gripping region,
and the position of the rearmost point of the second gripping region allow the second
gripping region to fill the palm of a user's hand without significant gaps, without
creating pressure points in the palm, and without forcing the palm upward or rearward
to push the fingers out of alignment with the tool axis and the trigger, resulting
in a more ergonomic grip. Third, the angle of the trigger axis relative to the tool
axis and the handle axis, and the position of the lock-on switch below the trigger
allow for more ergonomic actuation of the trigger and the lock-on switch. Fourth,
the depth and width of the handle at the trigger, at the fifth gripping surface, and
at sixth gripping surfaces result in a more ergonomic grip when the tool is being
gripped in the second position.
[0010] According to a first aspect of the present invention, there is provided a power tool
with an ergonomic handgrip comprising a housing with a rear end portion, a front end
portion, and lateral sidewalls, the housing defining a tool axis; a motor disposed
in the housing; a working end coupled to the front end portion of the housing, and
configured to be driven by the motor; a handle with a proximal portion coupled to
the housing, a distal end portion away from the housing, a rear wall portion, and
a front wall portion, the handle defining a handle axis; a trigger coupled to the
handle, the trigger defining a trigger axis extending in a direction of trigger movement;
a first gripping region including a rear concave recess on the rear end portion of
the housing and a lateral concave recess extending along one of the lateral sidewalls
of the housing generally parallel to the tool axis, the rear concave recess having
an innermost point that is closest to the front end portion of the housing; and a
second gripping region including a convex surface on the rear wall portion of the
proximal portion of the handle, wherein a vertical line extending from the innermost
point generally perpendicular to the tool axis intersects the trigger axis at a first
intersection point that is forward of a second intersection point where the trigger
axis intersects the handle axis.
[0011] According to a second aspect of the present invention, there is provided a power
tool with an ergonomic handgrip comprising a housing with a rear end portion, a front
end portion, and lateral sidewalls, the housing defining a tool axis; a motor disposed
in the housing; a working end coupled to the front end portion of the housing, and
configured to be driven by the motor; a handle with a proximal portion coupled to
the housing, a distal end portion away from the housing, a rear wall portion, and
a front wall portion, the handle defining a handle axis; a trigger coupled to the
handle, the trigger defining a trigger axis extending in a direction of trigger movement;
a first gripping region including a rear concave recess on the rear end portion of
the housing and a lateral concave recess extending along one of the lateral sidewalls
of the housing generally parallel to the tool axis; and a second gripping region including
a convex surface on the rear wall portion of the proximal portion of the handle, wherein
the convex surface has a curvature defined by an ellipse that with an eccentricity
of less than 0.5.
[0012] The trigger axis can be generally perpendicular to the handle axis. Alternatively,
the trigger axis can be at an acute angle of at least 15 degrees to the tool axis.
[0013] The ellipse can have a center proximate to the trigger axis.
[0014] The ellipse can have a minor axis generally parallel to the tool axis and a major
axis generally perpendicular to the tool axis.
[0015] The power tool can further comprise a fourth gripping surface on the rear wall portion
of the distal portion of the handle extending along the handle to a point distal of
the trigger. In such a power tool, the ergonomic handgrip can be configured to be
grasped in one of: (a) a first grip position where the first gripping region receives
a thumb and a forefinger of a user, the second gripping region receives in a palm
of the user, and the trigger receives a ring finger of the user; and (b) a second
grip position where the second gripping portion receives the thumb of the user, the
trigger receives the forefinger of the user, and the fourth gripping region receives
the palm of the user.
[0016] According to a third aspect of the present invention, there is provided a power tool
with an ergonomic handgrip comprising a housing with a rear end portion, a first front
end portion, a second front end portion, and lateral sidewalls, the housing defining
a tool axis; a motor disposed in the housing; a working end coupled to the front end
portion of the housing, and configured to be driven by the motor; a handle with a
proximal portion coupled to the housing, a distal end portion away from the housing,
a rear wall portion, a front wall portion, and a pair of sidewalls, the handle defining
a handle axis; a trigger coupled to the handle, the trigger defining a trigger axis
extending in a direction of trigger movement; a first gripping region including a
rear concave recess on the rear end portion of the housing and a lateral concave recess
extending along one of the lateral sidewalls of the housing generally parallel to
the tool axis; a second gripping region including a convex surface on the rear wall
portion of the proximal portion of the handle; a third gripping region on the second
front end portion of the housing and offset rearward from first front end portion;
a fourth gripping region on the rear end portion of the distal portion of the handle;
a fifth gripping region on the front wall portion of the distal portion of handle
adjacent the trigger; and a sixth gripping region on the front wall portion of the
distal portion of the handle, distal of the fifth gripping region, wherein the handle
has a first depth from the trigger to the convex gripping surface, a second depth
from the fifth gripping region to the fourth gripping region, and a third depth from
the sixth gripping region to the fourth gripping region, the first depth being greater
than the second depth, and the second depth being greater than the third depth, and
wherein the handle has a first width between the sidewalls at the trigger, a second
width between the sidewalls at the fifth gripping region, and a third width between
the sidewalls at the sixth gripping region, the first width being less than the second
width, and the second width being approximately equal to the third width.
[0017] These and other advantages and features will be apparent from the description, the
drawings, and the claims.
FIG. 1 is a perspective view of an exemplary embodiment of a screwdriver.
FIG. 2 is a left side view of the screwdriver of FIG. 1 with a portion of the exterior
housing removed.
FIGS. 3A and 3B are left side views of the screwdriver of FIG. 1.
FIG. 4 is a close-up view of the trigger on the screwdriver of FIG. 1.
FIG. 5 is a front view of the screwdriver of FIG. 1.
FIG. 6 is a rear view of the screwdriver of FIG. 1.
FIG. 7 is a schematic illustration of the anatomy of a user's hand.
FIG. 8 is a right side view of the screwdriver of FIG. 1 being gripped in a first
position.
FIG. 9 is a left side view of the screwdriver of FIG. 1 being gripped in the first
position.
FIG. 10 is a right side view of the screwdriver of FIG. 1 being gripped in a second
position.
FIG. 11 is a left side view of the screwdriver of FIG. 1 being gripped in the second
position.
FIG. 12 is a close up left-side view of the screwdriver of FIG. 1.
[0018] Referring to FIGS. 1 and 2, in one embodiment, a power tool 10 has a housing 12 having
a front end portion 18, a rear end portion 22, and sidewalls and defining a tool axis
X-X. The housing 12 includes a motor housing portion 13 that contains a rotary motor
14 and a transmission housing portion 15 that contains a parallel axis transmission
20 that transmits rotary motion from the motor 14 to an output spindle 26. Coupled
to the front end portion 18 of the transmission housing portion 15 and mechanically
connected to the output spindle 26 is a working end or tool holder 16 for retaining
a tool bit (e.g., a drill bit or screw driving bit, not shown) and defining a tool
holder axis X-X. As shown, the tool holder 16 includes a hex bit retention mechanism.
Further details regarding exemplary tool holders are set forth in commonly-owned
U.S. Patent Application Nos. 12/394,426 and
14/186,088, which are incorporated herein by reference. The working end 16 could encompass other
elements, such as a different hex bit holder, a chuck, a nosepiece of a nailer or
stapler, or a saw blade holder. The motor 14 drives the working end or tool holder
16 via the transmission 20 and the output spindle 26. A nosepiece or magazine may
optionally be coupled to the front end portion 18 of the housing 12, as described
and shown in the aforementioned
U.S. Patent Application No. 14/186,088, which is incorporated by reference.
[0019] Extending downward and slightly rearward of the housing 12 is a handle 40 in a pistol
grip formation. The handle 40 has a proximal portion 42 coupled to the housing 12
and a distal portion 44 coupled to a battery receptacle 28. The handle 40 also has
a first front wall portion 43 and a second front wall portion 59 facing the tool holder
16 side of the tool, a rear wall portion 41 facing away from the tool holder 16 side
of the tool, and sidewalls 49. The handle 40 extends generally along a handle axis
Y-Y that is at an obtuse angle α to the tool bit holder axis X-X and that lies along
a midline of the handle 40. For example, the angle α may be approximately 100-115
degrees, e.g., approximately 106 degrees, such that the distal portion 44 is located
generally rearward and downward of the rear end portion 22 of the housing 12. It should
be understood that this angle can be varied among a wide range of angles.
[0020] The motor 14 may be powered by an electrical power source, e.g., a battery (not shown),
which is coupled to the battery receptacle 28. A trigger 30 is coupled to the handle
40 adjacent the motor housing portion 13 of the housing 12. The trigger 30 electrically
connects the battery (or other source of power) to the motor 14 via an electronic
switch and control module 29 for controlling power delivery to the motor 14. The trigger
30 defines a trigger axis Z-Z extending along the direction of trigger travel, which
is generally perpendicular to the handle axis Y-Y. A light unit (e.g., an LED) 27
may be disposed on the battery receptacle 28 and may be angled to illuminate an area
in front of the tool holder 16. Power delivery to the light unit 27 may be controlled
by the trigger 30 and the electronic switch and control module 29, or by a separate
switch on the tool. As shown in the drawings, the power tool is a battery powered
cordless screwdriver. However, it should be understood that the tool may be any type
of corded, cordless, pneumatic, or combustion powered tool, such as a drill, an impact
driver, a wrench, a hammer, a hammer drill, a nailer, a stapler, a saw, a grinder,
a sander, or a router.
[0021] Referring to FIG. 3A, the power tool 10 includes an ergonomic handgrip 50 designed
to be contoured to a user's hand. The ergonomic handgrip 50 includes a first gripping
region 52 on the transmission housing portion 15, a second gripping region 54 on the
rear wall portion 41 of the proximal portion 42 of the handle 40, a third gripping
region 53 on the motor housing portion 13, a fourth gripping region 56 on the rear
wall portion 41 of the distal portion 44 of the handle 40, a fifth gripping region
45 on a front wall portion 43 of the proximal portion 46 of the handle 40 adjacent
to the trigger 30, and a sixth gripping region 47 on the front wall portion 43 of
the proximal portion 46 of the handle 40 distal of the fifth gripping region 45 and
adjacent the battery receptacle 28. One or more of the gripping regions 52, 53, 54,
56, 45, 47 may be formed or covered with an elastomeric material, such as rubber or
a resilient plastic material, and may include one or more ridges or recesses to facilitate
gripping of these regions.
[0022] Referring also to FIGS. 3B-6 and 12, the first gripping region 52 has a pair of longitudinal
concave recesses 56 extending generally along or parallel to the tool axis X-X on
opposite sidewalls 58 of the transmission housing portion 15. The longitudinal concave
recesses 56 extend along most of the length of the transmission housing portion 15,
and include ridges 61 to enhance gripping of the recesses 56. The first gripping region
52 also has a rear concave recess 60 in communication with the longitudinal concave
recesses 56 and wrapping around the rear end portion 22 of the housing 12. The rear
concave recess 60 has a concave curvature having a radius of curvature R1 of approximately
10 mm to 15 mm (e.g., approximately 13.5 mm). When viewed from the side as shown in
FIG. 3B, the rear concave recess 60 has an innermost point 64 that is closest to the
first front end portion 18 of the housing 12. The innermost point 64 generally coincides
with or is proximate to the tool axis X-X. The first gripping region 52 has a first
height H1 of approximately 25 mm to 35 mm (e.g., approximately 27 mm).
[0023] The second gripping region 54 includes a generally convex gripping surface 65 that
wraps around the rear wall portion 41 of the proximal portion 42 of the handle 40
and covers at least a portion of the sidewalls 49 of the handle 40. As shown in FIG.
12, the convex gripping surface 65 has a curvature that is generally defined by an
ellipse 66 centered at a center point 68 that is proximate the trigger axis Z-Z and
that is positioned below and in front of the trigger 30. The ellipse 66 has a minor
or horizontal axis 72 that is generally parallel to the tool axis X-X and a major
or vertical axis 70 that is generally transverse to the tool axis X-X. The major axis
70 has a length "a" of approximately 142 mm to 152 mm (e.g., approximately 152 mm),
and the minor axis 72 has a length "b" of approximately 135 mm to 145 mm e.g., approximately
140 mm). In one embodiment, both the major axis 70 and the minor axis 72 intersect
at least a portion of the trigger 30. Although the center point 68 is not shown as
intersecting the trigger axis Z-Z, it should be understood that they may intersect.
It should also be understood that the ellipse 66 may instead be a circle, or may have
a major axis in the horizontal direction or in a direction transverse to the vertical
and horizontal directions.
[0024] The ellipse 66 has a relatively small eccentricity. Eccentricity is a measurement
the amount that an elliptical shape surface deviates from circular, and is given by
the following equation:
where a = ½ the length of the major axis 70 and b = ½ the length of the minor axis
72. Eccentricity is measured on a scale of 0 to 1, with 0 being circular, and values
approaching 1 being elongated in one direction and flattened in the other direction,
approaching a straight line. In the illustrated embodiment, the ellipse 66 that defines
the concave gripping surface has an eccentricity of is less than 0.5, such as, for
example, between approximately 0.3 and 0.4. In one possible embodiment, the eccentricity
of the ellipse may be approximately 0.38.
[0025] The second gripping region 54 has a second height H2 of approximately 50 mm to 65
mm (e.g., approximately 58 mm). The second gripping region 54 also has a rearmost
point 57 at a point farthest rearward and distal from the innermost point 64. The
rearmost point 57 is positioned a distal distance DD of approximately 70 mm to 80
mm (e.g., approximately 71 mm) distally of the innermost point 65, and a rearward
distance RD of approximately 26 mm to 32 mm (e.g., approximately 29 mm) rearward of
the innermost point 65. The rearmost point 57 is also generally proximate to the rearward
end of the minor or horizontal axis 70 of the ellipse 66.
[0026] The third gripping region 53 comprises a generally flat gripping surface 59 that
is disposed on the second front end portion 55 on the motor housing portion 13 and
that partially wraps around the sides of the motor housing portion 13. The third gripping
region 53 has a height H3 and is disposed a first offset distance L1 forward of the
innermost point 64 of the concave recess 60 and a second offset distance L2 from the
front end portion of the longitudinal concave recess 56. The height H3 may be approximately
25 mm to 35 mm (e.g., approximately 30 mm)., the first offset distance L1 may be approximately
50 mm to 95 mm (e.g., approximately 84 mm), and the second offset distance L2 may
be approximately 13 mm to 64 mm (e.g., approximately 27 mm).
[0027] The fourth gripping region 56 has a gripping surface 63 that wraps around the rear
wall portion 41 of the distal portion 44 of the handle 40 and covers at least a portion
of the sidewalls 49 of the handle 40. When viewed from the side as in FIG. 3B, the
gripping surface 63 is substantially straight with a slight convex curvature. The
fourth gripping region 56 has a height H4 of approximately 60 mm to 70 mm (e.g., approximately
65 mm).
[0028] The fifth gripping region 45 comprises a generally flat front resting surface 80
formed on the front wall portion 45 of the distal portion 44 of the handle 40 adjacent
the trigger 30, and side resting surfaces 82 formed on the sidewalls 49 of the distal
portion 44 of the handle 40. Disposed on the finger resting surface 80 is a lock-on
switch 74 that can be actuated to lock-on the trigger 30 when it is depressed. The
fifth gripping region 45 a height H5 of approximately one finger width, e.g., approximately
20 mm to 30 mm (e.g., approximately 25 mm).
[0029] The sixth gripping region 47 comprises a generally convex finger resting surface
84 that wraps around the front wall portion 45 of the distal portion 44 of the handle
40 and onto both sidewalls of the handle 40, distal of the fifth gripping region 45
and adjacent the battery receptacle 28. The convex finger resting surface 84 may be
joined with the side resting surfaces 82 as one continuous surface. The sixth gripping
region 47 has a height H6 of approximately one finger width, e.g., approximately 20
mm to 30 mm (e.g., approximately 25 mm).
[0030] The trigger 30 generally has an L-shape with a generally straight front surface 33
and a generally straight top surface 35 joined by a curved corner surface 37. The
front surface 33 has a height H7 of approximately two finger widths, for example approximately
33 mm to 43 mm (e.g., approximately 38 mm). The straight top surface 35 has a depth
D of approximately 8 mm to 15 mm (e.g., approximately 11 mm). The curved corner surface
37 has a radius of curvature R2 of approximately 7 mm to 13 mm (e.g., approximately
10 mm) defined by a circle 39 with a center point C. The trigger axis Z-Z extends
through the center point C in the direction of trigger travel, generally perpendicular
to the handle axis Y-Y. The trigger axis Z-Z is at an acute angle β of at least 15
degrees, e.g., approximately 15 to 20 degrees (such as 17 degrees) to a line L-L that
is parallel to the tool holder axis X-X.
[0031] The ergonomic grip 50 facilitates ergonomic gripping of the tool by a user's hand
in two different grip positions during operation of the tool. FIG. 7 illustrates the
anatomical parts of a user's hand. Generally, a user's hand 100 includes a palm 101
to which is connected a thumb 102, a forefinger 104, a middle finger 106, a ring finger
108, and a pinky finger 110. A web 112 of muscles connects the base of the thumb 102
and forefinger 104. In addition, the palm 101 includes a center region 111 flanked
by two fleshy pads in the form of a thenar eminence 114 on the thumb side of the palm
and the hypothenar eminence 116 on the pinky side of the palm. Further, there are
fleshy pads 118, 120, 122, 124, and 126 on the palm 101 at the base of the thumb 118
and each finger 104, 106, 108, and 110.
[0032] The handle 40 has a first depth D1 and a first width W1 at the trigger, a second
depth D2 and a second width W2 at the fifth gripping region 45, and a third depth
D3 and a third width W3 at the sixth gripping region 47. The first, second, and third
depths D1, D2, D3 are measured from the trigger to the second gripping region 54,
from the fifth gripping region 45 to the fourth gripping region 56, and from the sixth
gripping region 47 to the fourth gripping region, respectively. The first depth D1
is greater than the second depth D2, which is greater than the third depth D3. For
example, the first depth D1 is approximately 45 mm to 55 mm (e.g., approximately 50
mm), the second depth D2 is approximately 40 mm to 45 mm (e.g., approximately 42 mm),
and the third depth D3 is approximately 35 mm to 40 mm (e.g., approximately 37 mm).
The first, second and third widths W1, W2, W3 are measured between sidewalls 49 of
the handle 40 at the trigger 30, at the fifth gripping region 45 and at the sixth
gripping region 47, respectively. The first width W1 is less than the second width
W2, which is approximately equal to the third width W3. For example, the first width
W1 is approximately 30 mm to 35 mm (e.g., approximately 32 mm), the second width W2
is approximately 31 mm to 36 mm (e.g., approximately 35 mm), and the third width W3
is approximately 28 mm to 37 mm (e.g., approximately 35 mm).
[0033] Referring to FIGS. 8 and 9, when gripped in the first grip position, the longitudinal
concave recesses 56 of the concave gripping region 52 receive the thumb 102 and forefinger
104, which are generally aligned along the tool holder axis X-X. The rear concave
recess 60 receives the web 112 that connects the thumb 102 and forefinger 104. The
second gripping region 54 is received in the center region 111 of the palm 101 with
the thenar eminence 114 on one side of the second gripping region 54 and the hypothenar
eminence 116 on the other side of the second gripping region 54. The middle finger
106 rests alongside the motor housing portion 13 with the fingertip of the middle
finger 106 resting on the third gripping region 53. The ring finger 108 and the pinky
finger 110 rest on the trigger 30 and are used to actuate the trigger 30. The pinky
finger 110 can also be used to actuate the lock-on switch 74.
[0034] Referring to FIGS. 10 and 11, when gripped in the second grip position, the fourth
gripping region 56 receives the center region 111 of the palm 100 with the thenar
eminence 114 on one side of the fourth gripping region 56 and the hypothenar eminence
116 on the other side of the fourth gripping region 56. The forefinger 104 and middle
finger 106 are received on the trigger 30. The ring finger 108 is positioned to rest
on the front surface resting surface 80 and side resting surface 82 of the fifth gripping
region 45. The pinky finger 110 is positioned to rest on the finger resting surface
84 of the sixth gripping region 47. The web 112 and thumb 102 rest on the second gripping
surface 54. The trigger is actuated using the forefinger 104 and/or middle finger
106, while the lock-on switch 74 is actuated using the ring finger 108.
[0035] One or more of the following features, alone or together, proved the handgrip 50
with superior ergonomics. First, the position of the innermost point 64 of the first
gripping region 52 results in a more ergonomic design. A vertical line V-V taken from
the innermost point 64 on the rear concave recess 60 intersects the trigger axis Z-Z
at an intersection point 86 that is forward of the handle axis Y-Y. This configuration
allows the web 112 between the thumb 102 and forefinger 104 to lie in a plane that
is closer to the trigger 30 when the handle 40 is gripped in the first position. This
allows the user's grip to be centered forward of the handle axis, resulting in a more
ergonomic grip and easier actuation of the trigger.
[0036] Second, the configuration of second gripping region 54 results in a more ergonomic
grip. Advantageously, the ellipse 66 that defines the second gripping region 54 has
a relatively low eccentricity of less than 0.5, such as 0.3 to 0.4, resulting in a
curvature that is neither too shallow nor too sharp. In addition, the rearmost point
57 of the second gripping region 54 is positioned proximate the rear end point to
the horizontal axis 70 of the ellipse 66. The rearmost point 57 is positioned at a
distance DD of approximately 70 mm to 80 mm (e.g., approximately 71 mm) distally of
the innermost point 65, and a rearward distance RD of approximately 26 mm to 32 mm
(e.g., approximately 29 mm) from the innermost point 64 of the first gripping region
52. Further, the center point 68 of the ellipse 66 is positioned just below and in
front of the trigger, and within the circle 39 that defines the radius R2 of the curved
trigger surface 37. These aspects of the second gripping region 54 allow the second
gripping region 54 to fill the palm of a user's hand without significant gaps, without
creating pressure points in the palm, and without forcing the palm upward or rearward
to push the fingers out of alignment with the tool axis and the trigger.
[0037] Third, the configuration of the trigger 30 and lock-on switch 74 results in a more
ergonomic grip. The trigger 30 travels along the trigger axis Z-Z, at an acute angle
β of at least 15 degrees to the tool holder axis X-X (e.g., approximately 17-20 degrees).
The trigger axis Z-Z is also generally perpendicular to the handle axis Y-Y. This
orientation of the trigger axis Z-Z results in a more ergonomic and natural movement
for the ring finger and pinky finger to pull the trigger when the tool is being gripped
in the first position, and for the forefinger and middle finger to pull the trigger
when the tool is being gripped in the second position. Further, the lock-on switch
74 is positioned on the fifth gripping region 45, just below the trigger 30. This
allows the pinky to actuate the lock-on switch 74 when the tool is gripped in the
first position and the ring finger to actuate the lock-on switch 74 when the tool
is gripped in the second position.
[0038] Finally, the configuration of the fourth, fifth and sixth gripping surfaces result
in a more ergonomic grip when the tool is being gripped in the second position. The
first depth D1 at the trigger is greater than a second depth D2 at the fifth gripping
region 45, which is greater than the third depth D3 at the sixth gripping region 47.
At the same time, the first width W1 at the trigger 30 is smaller than the second
width W2 at the fifth gripping region 45, which is approximately equal to the third
width W3 at the sixth gripping region 47. Having the smallest width W1 and largest
depth D1 at the trigger 30 allows the sides of the handle to comfortably receive the
thenar eminence 114 and the hypothenar eminence 116 while the forefinger and middle
finger grasp the trigger. The larger widths W2 and W3 at the finger rests 43 and 45
allow the handle to be comfortably received in the center of the palm. The larger
depth D2 at the finger rest 43 than the depth D3 at the finger rest 45 provides a
more comfortable grip for the larger ring ringer and smaller pinky finger.
[0039] Numerous modifications may be made to the exemplary implementations described above.
For example, the trigger may be moved upward and rearward on the housing so that it
is closer to the tool axis and to the handle axis. Also, the housing may have only
one portion with the motor being in-line with the transmission or directly driving
the working end without a transmission. These and other implementations are within
the scope of the following claims.
1. A power tool with an ergonomic handgrip comprising:
a housing with a rear end portion, a front end portion, and lateral sidewalls, the
housing defining a tool axis;
a motor disposed in the housing;
a working end coupled to the front end portion of the housing, and configured to be
driven by the motor;
a handle with a proximal portion coupled to the housing, a distal end portion away
from the housing, a rear wall portion, and a front wall portion, the handle defining
a handle axis;
a trigger coupled to the handle, the trigger defining a trigger axis extending in
a direction of trigger movement;
a first gripping region including a rear concave recess on the rear end portion of
the housing and a lateral concave recess extending along one of the lateral sidewalls
of the housing generally parallel to the tool axis, the rear concave recess having
an innermost point that is closest to the front end portion of the housing; and
a second gripping region including a convex surface on the rear wall portion of the
proximal portion of the handle,
wherein a vertical line extending from the innermost point generally perpendicular
to the tool axis intersects the trigger axis at a first intersection point that is
forward of a second intersection point where the trigger axis intersects the handle
axis.
2. The power tool of claim 1, further comprising a third gripping region disposed on
the housing, and offset rearward of the front end portion of the housing.
3. The power tool of claim 1, wherein the trigger axis is generally perpendicular to
the handle axis.
4. The power tool of claim 1, wherein the trigger axis is at an acute angle of at least
15 degrees to the tool axis.
5. The power tool of claim 1, wherein the convex surface has a curvature defined by an
ellipse that has an eccentricity of less than 0.5.
6. The power tool of claim 5, wherein the ellipse has a center proximate to the trigger
axis.
7. The power tool of claim 5, wherein the ellipse has a minor axis generally parallel
to the tool axis and a major axis generally perpendicular to the tool axis.
8. The power tool of claim 1, wherein the convex surface has a rearmost point that is
approximately 26 mm to 32 mm rearward of the innermost point and approximately 70
mm to 80 mm distal of the innermost point.
9. The power tool of claim 1, further comprising a fourth gripping surface on the rear
wall portion of the distal portion of the handle extending along the handle to a point
distal of the trigger.
10. The power tool of claim 9, wherein the ergonomic handgrip is configured to be grasped
in one of: (a) a first grip position where the first gripping region receives a thumb
and a forefinger of a user, the second gripping region receives in a palm of the user,
and the trigger receives at least one of a ring finger and a pinky finger of the user;
and (b) a second grip position where the second gripping portion receives the thumb
of the user, the trigger receives at least one of the forefinger and the middle finger
of the user, and the fourth gripping region receives the palm of the user.
11. The power tool of claim 1, wherein the rear concave recess has an innermost point
that is closest to the front end portion of the housing, and the convex surface has
a rearmost point that is approximately 26 mm to 32 mm rearward of the innermost point
and approximately 70 mm to 80 mm distal of the innermost point.
12. A power tool with an ergonomic handgrip comprising:
a housing with a rear end portion, a front end portion, and lateral sidewalls, the
housing defining a tool axis;
a motor disposed in the housing;
a working end coupled to the front end portion of the housing, and configured to be
driven by the motor;
a handle with a proximal portion coupled to the housing, a distal end portion away
from the housing, a rear wall portion, and a front wall portion, the handle defining
a handle axis;
a trigger coupled to the handle, the trigger defining a trigger axis extending in
a direction of trigger movement;
a first gripping region including a rear concave recess on the rear end portion of
the housing and a lateral concave recess extending along one of the lateral sidewalls
of the housing generally parallel to the tool axis; and
a second gripping region including a convex surface on the rear wall portion of the
proximal portion of the handle,
wherein the convex surface has a curvature defined by an ellipse that with an eccentricity
of less than 0.5.
13. A power tool with an ergonomic handgrip comprising:
a housing with a rear end portion, a first front end portion, a second front end portion,
and lateral sidewalls, the housing defining a tool axis;
a motor disposed in the housing;
a working end coupled to the front end portion of the housing, and configured to be
driven by the motor;
a handle with a proximal portion coupled to the housing, a distal end portion away
from the housing, a rear wall portion, a front wall portion, and a pair of sidewalls,
the handle defining a handle axis;
a trigger coupled to the handle, the trigger defining a trigger axis extending in
a direction of trigger movement;
a first gripping region including a rear concave recess on the rear end portion of
the housing and a lateral concave recess extending along one of the lateral sidewalls
of the housing generally parallel to the tool axis;
a second gripping region including a convex surface on the rear wall portion of the
proximal portion of the handle;
a third gripping region on the second front end portion of the housing and offset
rearward from first front end portion;
a fourth gripping region on the rear end portion of the distal portion of the handle;
a fifth gripping region on the front wall portion of the distal portion of handle
adjacent the trigger; and
a sixth gripping region on the front wall portion of the distal portion of the handle,
distal of the fifth gripping region,
wherein the handle has a first depth from the trigger to the convex gripping surface,
a second depth from the fifth gripping region to the fourth gripping region, and a
third depth from the sixth gripping region to the fourth gripping region, the first
depth being greater than the second depth, and the second depth being greater than
the third depth, and
wherein the handle has a first width between the sidewalls at the trigger, a second
width between the sidewalls at the fifth gripping region, and a third width between
the sidewalls at the sixth gripping region, the first width being less than the second
width, and the second width being approximately equal to the third width.
14. The power tool of claim 13, wherein the gripping regions are configured to be grasped
in one of: (a) a first grip position where the lateral concave recesses receives a
thumb and a forefinger of a user, the rear concave recess receives a web between the
thumb and the forefinger of the user, the convex gripping surface is received in a
palm of the user, the third gripping region receives a middle finger of the user,
and the trigger receives at least one of a ring finger and a pinky finger of the user;
and (b) a second grip position where the fourth gripping region receives the palm
of the user, the convex gripping surface receives the web and the thumb of the user,
the fifth gripping region receives the ring finger of the user, the sixth gripping
region receives the pinky finger of the user, and the trigger receives at least one
of the forefinger and the middle finger of the user.
15. The power tool of claim 14, further comprising a trigger lock-on switch on the fifth
gripping region.