Note: Descriptions are shown in the official language in which they were submitted.
CA 02368535 2002-O1-18
TITLE OF THE INVEN2.'ION
Manipulation Levers of Forklift and Forklift
BACKGROUND OF THE INVENTION
The present invention relates to a manipulation lever
of a forklift. Particularly, the present invention pertains
to a manipulation lever of a forklift in which an operator
IO stands.
In a typical reach type battery-powered forklift, in
which an operator stands, an operator's cab is located in
the vicinity of the rear side of the body frame. An
operator in the operator's cab operates the forklift to move
and handle a load. The operator's cab is defined by a side
frame, which is on the left side, a front frame, and a guard
frame, which is on the right side.
Fig. 7 is a partial front view o:~ a reach type
forklift in which an operator stands. A steering wheel 1 is
arranged on a side panel, which is located at the upper
portion of the side frame. For example, a lift lever 3, a
tilt lever 4, and a reach lever 5 are arranged on a front
panel 2, which is located at the upper portion of the front
frame. The lift lever 3 is used for 1_ifting and lowering a
fork. The tilt lever 4 is used for tiating the fork. The
reach lever 5 is used for moving masts. A driving lever 6,
which is used for moving the body frame, is provided on the
right side portion of the front panel 2. The lift lever 3,
the tilt lever 4, the reach lever 5, and the driving lever 6
tilt forward and rearward.
An operator 7 handles the steering wheel 1 with the
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left hand. Meanwhile, the operator 7 handles the lift lever
3, the tilt lever 4, the reach lever 5, and the driving
lever 6 with the right hand. In the reach type forklift,
the operator 7 is frequently required to handle a load, or
particularly, to lift and lower a fork, and to move the body
frame at the same time or consecutively. Therefore, the
operator 7 handles the lift lever 3, the tilt lever 4, and
the reach lever 5 with the right hand while operating the
driving lever 6 with the right forearm or the right elbow.
When the operator 7 needs to change the moving
direction of the body frame from forward to rearward while
lifting or lowering the fork, the operator 7 needs to lift
the right arm and grasp the lever-3 again before pressing
the driving lever 6 rearward. Such operation. is complicated
and decreases efficiency. Further, when handling a load,
the above mentioned operation is frequently performed. Thus,
the operator 7 gets more and more tired.
Japanese Laid-Open Patent Publication No. 10-236797
discloses a manipulation lever, which is selectively tilted
forward, rearward, leftward, and rightward. When the
manipulation lever is tilted forward or rearward, the
vehicle moves accordingly. When the manipulation lever is
tilted leftward or rightward, a fork is lifted or lowered
accordingly.
According to the above mentioned manipulation lever,
the direction of the movement of the fork differs from that
of the lever. Therefore, an operator feels uncomfortable
and takes long time until the operator masters the lever
operation.
SUMMARY OF THE INVENTION
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The objective of the present invention is to provide a
manipulation lever that facilitates operation for handling a
load and moving the forklift.
To achieve the foregoing objective, the present
invention provides a manipulation lever located on the body
frame of a forklift. The lever includes a lever body, a
grip, and a knob. The lever body is arranged on the body
frame to be tilted. The grip is arranged on the lever body.
The shape of the grip is formed to be grasped with a hand
with the palm facing down. The knob is rotatably arranged
on the grip. The knob is rotated by selectively moving the
knob upward and downward with the thumb of a hand grasping
the grip.
The present invention also provides a forklift that
has an operator's cab in which an operator stands. The
forklift includes a front panel located at the front portion
of the operator's cab, a manipulation lever, a first
detecting apparatus, a second detecting apparatus, and a
controller. The manipulation lever includes a lever body, a
grip, and a knob. The lever body .is arranged on the front
panel and selectively tilted forward and backward. The grip
is arranged on the lever body. The shape of the grip is
formed to be grasped with a hand with the palm facing down.
The knob is rotatably arranged on the grip. The knob is
rotated by moving the knob upward and downward with the
thumb of a hand grasping the grip. The first detecting
apparatus detects the inclination direction and the
inclination angle of the lever body. The second detecting
apparatus is located in the grip. The second detecting
apparatus detects the rotation direction and the rotation
angle of the knob. The controller controls the base frame'
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to move in the same direction as the inclination direction
of the lever body in accordance with the detected value of
the first detecting apparatus, and controls a fork to be
lifted and lowered in the same direction as the rotating
direction of the knob in accordance with the detected value
of the second detecting apparatus.
Other aspects and advantages of the invention will
become apparent from the following description, taken in
conjunction with the accompanying drawings, illustrating by
way of example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention, together with objects and advantages
thereof, may best be understood by reference to the
following description of the presently preferred embodiments
together with the accompanying drawings in which:
Fig. 1 is a partial perspective view illustrating a
reach type battery-powered forklift, in which an operator
stands, according to a first embodiment of the present
invention;
Fig. 2 is a perspective view illustrating the
manipulation lever provided in the forklift shown in Fig. l;
Fig. 3 is a plan view of the manipulation lever shown
in Fig. 2;
Fig. 4 is a side view illustrating the manipulation
lever taken along line 4-4 shown in Fig. 3;
' Fig. 5 is a side view illustrating the grip of the
manipulation lever taken along line 5-5 shown in Fig. 4;
Fig. 6 is a schematic diagram illustrating a control
system for moving the fork lift and handling a load in
relation to the manipulation lever of 'the present invention;
and
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Fig. 7 is a partial front view illustrating a prior
art reach type battery-powered forklift.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A reach type battery-powered forklift 10 according to
a first embodiment of the present invention will now be
described with reference to Figs. 1 to 6. Fig. 1 shows a
part of an operator's cab 12 of the forklift 10. An
operator ? stands in the operator's cab 12 of the forklift
10 when operating the forklift 10 to move and handle a load.
The direction that the operator 7 looks at masts 14
from the operator's cab 12 is referred to as the forward
direction. The operator's cab 12 is defined by a front
frame 16, a side frame 18, which is on the left side, and a
guard frame 20, which is on the right side. The front frame
16 is provided on the front side of the body frame to cover,
for example, a controller and an oil control valve for
handling a load. The side frame 18 covers, for example, a
drive apparatus and a steering apparatus. An opening 22 is
provided between the rear end of the guard frame 20 and the
side frame 18 for the operator 7 to step on and off the
operator's cab 12. A waist supporter 24 for supporting the
waist of the operator ? is arranged on the upper inner
surface of the'curved portion of the guard frame 20.
A steering wheel 28 is arranged on a panel 26, which
is located at the upper portion of the side frame 18. A
manipulation lever 32 is arranged on a front panel 30, which
is located at the upper portion of the front frame I6. A
wrist supporter 34 protrudes from the front panel 30 for
supporting the right forearm and the right elbow of the
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operator 7.
Figs. 2 to 5 are detailed illustrations of the
manipulation lever 32. As shown in Fig. 4, the manipulation
lever 32 includes a lever body 36, which is rotatably
arranged on the front frame 16. The lever body 36 extends
upward through a slot 38, which is formed on the front panel
30. The slot 38 extends in the forward and rearward
direction of the body frame. The lever body 36 is
selectively tilted forward and rearward along the slot 38.
The lower end (not shown) of the lever body 36 is connected
to an input shaft of a first potentiometer 40 (a first
detecting apparatus} for detecting the inclination angle and
the inclination direction of the lever body 36. As shown in
a schematic diagram of Fig. 6, a detected value of the first
potentiometer 40 is sent to a controller 42, which is a
microcomputer. The controller 42 controls a drive apparatus
44 in accordance with the detected value so that the body
frame moves in accordance with the inclination of the lever
body 36. The inclination direction of the lever body 36 is
the same as the direction that the base frame is moved. A
spring (not shown) is arranged between the lever body 36 and
the input shaft of the first potentiometer 40. The lever
body 36 is retained in a neutral position, which is
substantially vertical, by the force of the spring when the
lever body 36 is not used.
As shown in Figs. 2 to 4, the manipulation lever 32
includes a grip 46, which is arranged on the upper end of
the lever body 36. The grip 46 preferably includes two
separate grip pieces 46a, 46b (see Fig. 3}, which are made
of synthetic resin. The upper end of the lever body 36 is
arranged between the grip pieces 46a, 46b. The grip pieces
46a, 46b are secured to each other with bolts and nuts and
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fixed on the lever body 36. The grip 46 extends along an
axis L in a bar-like shape, the shape of the grip 46 being
formed to be grasped with a hand with the palm facing down.
The operator 7 grasps the grip 46 with the right hand with
the palm facing down. The operator 7 grasps the grip 46
mainly with the third finger and the little finger.
Therefore, a right side portion 48 of the grip 46, which is
held by the third finger and the little finger, has narrow
width in the direction that is perpendicular to the axis L.
A left side portion 50 of the other end of the grip 46 has
broad width. The operator 7 puts the forefinger and the
middle finger on the upper surface bf the left side portion
50. A back surface portion 52 extends substantially
vertically from the base portion of the grip 46, or the
joint portion with the lever body 36. The operator 7 puts
the base of the thumb (ball of the thumb) of the right hand
on the back surface portion 52.
The operator 7 puts the right forearm and the right
elbow on the wrist supporter 34 and places the right forearm
in the left and right direction. That is, the operator 7
grasps the grip 46, such that the right forearm is parallel
with a horizontal X-axis, which extends in the width
direction of the base frame. Therefore, the grip 46 is
arranged on the lever body 36 in a way to permit the
operator 7 to easily grasp the grip 46. That is, as. shown
in Fig. 3, the axis L of the grip 46 is inclined
counterclockwise by an angle a, which is 30 to 60.degrees,
with respect to the X-axis as viewed from right above. For
the similar reason, when the lever body 36 is at the neutral
position, the axis L of the grip 46 is vertically inclined
with respect to the X-axis (see Fig. 4).
A substantially cylindrical knob 54 is arranged on the
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left end of the grip 46 and rotates about the axis L, so
that the knob 54 can be rotated by selectively moving the
knob upward and downward with the thumb of a hand grasping
the grip. The knob 54 is secured to the input shaft of a
second detecting apparatus, which is a second potentiometer
58 in this embodiment. The second potentiometer 58 is
embodied in the grip 46 with, for example, screws. More
preferably, the knob 54 is secured to an input shaft of the
decelerator (not shown), which is connected to the input
shaft of the second potentiometer 58, with, for example,
screws. A protrusion 56 extends along the axis L on the
outer circumferential surface of the knob 54. The operator
7 easily turns the knob 54 by pressing the protrusion 56
upward or downward with the thumb of the right hand, which
is grasping the grip 46. As shown in the schematic diagram
of Fig. 6, the second potentiometer 58, which is connected
to the knob 54, detects the rotation direction and the
rotation angle of the knob 54 and sends the detected value
to the controller 42. In the preferred embodiment, the
controller 42 controls a first oil control valve 62, which
is connected to a lift cylinder 60, in accordance with the
detected value sent from the second potentiometer 58 and
lifts or lowers a fork (not shown) along the masts 14. Thus,
the fork of the forklift is selectively lifted and lowered
in accordance with the rotation of the knob 54. The
protrusion moves in accordance with the movement of the
thumb, and the moving direction of the protrusion is the
same as the direction that the fork is selectively lifted
and lowered. The knob 54 is retained in a neutral position
by a spring (not shown), which is embedded in the
decelerator, when the knob 54 is not used. The term "knob"
includes means to rotate axis such as a lever.
Switching means for reaching masts, which is a seesaw
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switch 64 in this embodiment, is arranged on the left side
portion 50 of the grip 46. The seesaw switch 64 (or reach
switch) is arranged at a suitable place and in a suitable
direction for the operator 7 to operate mainly with the
forefinger of the right hand. One of the ends of the seesaw
switch 64 is located toward the front side of the base frame
and the other end is located toward the rear side of the
body frame. The seesaw switch 64 controls the forward and
rearward movement of the masts 14. The seesaw switch 64 is
connected to the controller 42. The controller 42 controls
a second oil control valve 68, which is connected to a reach
cylinder 66, in accordance with the output signal sent from
the seesaw switch.
A cruciform button 70 is located on the back surface
portion 52 of the grip 46. The cruciform button 70 is
arranged at a position such that the operator 7 presses with
the thumb of the right hand, which is grasping the grip 46.
The cruciform button 70 includes an upper end portion (first
end portion) 70a, a lower end portion (second end portion)
70b, a right side portion (third end portion) 70c, and a
left side portion (fourth end portion) 70d. The upper end
portion 70a and the lower end portion 70b of the cruciform
button 70 form tilt switching means for controlling the
inclination of the masts 14 in the forward and rearward
direction. As shown in Fig. 6, the controller 42 controls a
third oil control valve 74 of a tilt cylinder 72 in
accordance with the signal sent from the cruciform button 70
when the operator 7 presses the upper end portion 70a or the
lower end portion 70b. The mast 14 of the forklift is
selectively tilted forward and backward in accordance with
the operation of the tilt switch, and the operation
direction of the tilt switch is the same as the inclination
direction of the mast 14.
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A side shift attachment (not shown), which is one of
options of attachments for handling a load, is attached to
the forklift 10. The side shift attachment includes a side
shift cylinder 76, which is arranged on a lift bracket for
moving the fork left and right. The right side portion 70c
and the left side portion 70d of the cruciform button 70
correspond to the side shift attachment. The controller 42
controls a fourth oil control valve 78, which is connected
to the side shift cylinder 76, in accordance with a signal
sent from the cruciform button 70 when the operator 7
presses the right side portion 70c or the left side portion
70d.
A horn button 80 shown in Figs. 3 and 5 is arranged on
the front face of the left side portion 50 of the grip 46.
The horn button 80 is mainly pressed by the middle finger.
The operations for moving the forklift and handling a
load using the manipulation lever 32 are described below.
The operator 7 basically stands in a posture as shown
by a dotted line in Fig. 1. Specifica=Lly, the operator 7
stands in the operator's cab 12, rests the waist against the
waist supporter 24 on the guard frame 20, grasps the
steering wheel 28 with the left hand, and grasps the grip 46
of the manipulation lever 32 with the right hand. In this
state, the operator 7 rests the right elbow and the right
forearm near the right elbow on the wrist supporter 34,
which is located on the front panel 30. This keeps the
right hand, which grasps the grip 46 and the right forearm
substantially horizontal, thus reducing exhaustion of the
right arm. Furthermore, since the body is supported at two
positions, that is, by the waist supporter 24 and the wrist
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supporter 34, the body is stabilized. Also the posture of
the right arm is similar to the driving posture used in the
prior art reach type forklift shown in Fig. 7. Therefore,
even if the operator 7 is used to the prior art forklift,
the operator 7 easily operates the forklift 10, which has
the manipulation lever 32 according to the preferred
embodiment.
When the operator 7 moves the right forearm forward
using the right elbow as a fulcrum, th.e lever body 36 and
the grip 46 of the manipulation lever 32 are tilted forward.
At this time, the first potentiometer 40 detects the
inclination direction and the inclination angle of the lever
body 36 and sends the detected value to the controller 42.
As a result, the controller 42 controls the drive apparatus
44 and advances the forklift l0 at a speed corresponding to
the inclination angle of the manipulation lever 32.
When the operator 7 tilts the manipulation lever 32
forward, the right hand could slip off the grip 46.
Therefore, as shown in Figs. 2 to 5, a flange 82 is
preferably formed on the right end of the grip 46 to prevent
slipping of the hand. The flange 82 extends in a direction
that intersects the axis L of the grip 46. When the
operator 7 moves the right forearm rearward using the right
elbow as a fulcrum, the lever body 36 is tilted rearward.
Then, the forklift 10 moves rearward at a desired speed
corresponding to the inclination dire coon and the
inclination angle of the lever body 36.
While grasping the grip 46, the manipulation lever 32
is tilted, or the operation for moving the forklift is
performed, and the knob 54 is operated with the thumb,
subsequently. For example, when the protrusion 56 of the
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knob 54 is moved upward with the thumb, the controller 42
controls the first oil control valve 62 in accordance with
the output signal from the second potentiometer 58. The
first oil control valve 62 is controlled such that hydraulic
oil is supplied to the lift cylinder 60. Accordingly, the
fork is lifted. On the other hand, when the protrusion 56
of the knob 54 is moved downward, the controller 42 switches
the position of the first oil control valve 62. The
hydraulic oil in the lift cylinder 60 is returned to the oil
tank 84. Thus, the fork is lowered.
When the operator 7 exerts an upward force on the knob
54 with the thumb, the fork is lifted. When the operator 7
exerts a downward force on the knob 54 with the thumb, the
fork is lowered. Therefore, the direci~ion of movement of
the knob 54 is the same as the direction of the actual
movement of the fork. Thus, the operator 7 performs the
operation for lifting the fork without feeling uncomfortable.
While the operator 7 grasps the grip 46, the operation
for moving the forklift or the operation for lifting the
fork is performed and the seesaw switch 64 for reaching the
fork is operated with the forefinger consecutively. When
the operator 7 presses the front side end portion of the
seesaw switch 64, the controller 42 controls the second oil
control valve 68 in accordance with the output signal from
the seesaw switch 64. Then, a piston rod of the reach
cylinder 66 is extended. As a result, the masts 14 move
forward. When the operator 7 presses the rear side end
portion of the seesaw switch 64, the masts 14 move rearward.
Therefore, the direction of switching operation and the
actual movement of the masts 24 are the same. Thus, the
operator 7 easily operates the forklift..
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When the upper end portion 70a is pressed, the masts
14 are inclined forward. When the lower end portion 70b is
pressed, the masts 14 are inclined rearward. When the right
side portion 70c is pressed, the fork moves rightward. When
the left side portion 70d is pressed, the fork moves
leftward. Therefore, the operator 7 performs the operation
for tilting the masts 14 and the operation for side-shifting
the fork using the cruciform button 70 without feeling
uncomfortable. While moving the forklift or handling a load,
the operator 7 presses the horn button 80 with the middle
finger to sound the alarm.
It should be apparent to those skilled in the art that
the present invention may be embodied in many other specific
forms without departing from the spirit or scope of the
invention. Particularly, it should be understood that the
invention may be embodied in the following forms.
In the forklift, in which an operator stands, the
operation for moving,the forklift and the operation for
lifting and lowering the fork are often performed
consecutively. Therefore, the manipulation lever may be
designed such that only the lever body inclines and the knob
rotates. A manipulation lever, which is designed for each
operation, that is, the operation for reaching the fork, the
operation for tilting the masts, and the operation for side-
shifting the fork, may be provided separately.
In the preferred embodiment, the manipulation lever 32
of the present invention is applied to the forklift, in
which an operator stands. However, the manipulation lever
32 may be applied to a counter-balance type forklift. In
this case, the fork is lifted or lowered in accordance with
the upward or downward rotation of the knob, and the masts
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are tilted in accordance with the forward or backward
inclination of the lever body.
The manipulation lever 32 of the present invention is
applied to a forklift in which masts and a fork are
integrally tilted, however, the manipulation lever 32 may be
applied to a forklift in which only a fork is tilted.
Therefore, the present examples and embodiments are to
be considered as illustrative and not restrictive and the
invention is not to be limited to the details given herein,
but may be modified within the scope and equivalence of the
appended claims.
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