TECHNICAL FIELD
[0001] The present invention relates to a head guard structure for a forklift.
BACKGROUND
[0002] A head guard is mounted to a forklift used to carry, load, and unload various loads.
A head guard is a guard unit for protecting a driver from a fallen load when a load
falls due to collapse of loads upon loading or unloading loads at a height.
[0003] The head guard includes a pair of right and left front pillars disposed at the front
of a vehicle of a forklift at intervals in the vehicle width direction, a right and
left rear pillars disposed at the rear of the vehicle at intervals in the vehicle
width direction, and a ceiling disposed over the front pillars and the rear pillars.
The head guard has high rigidity to protect the driver from fallen objects.
[0004] Patent Document 1 discloses an attachment structure of a head guard.
[0005] According to Patent Document 1, an attachment structure includes a fixing metal piece
disposed on a weight of a forklift, and an attachment part of a rear frame of a head
guard is fastened to the metal piece by bolts.
[0006] Further, a bolt inlet is disposed on a wall of the attachment part centrally in the
vehicle width direction, and a screw member is disposed on the metal piece. An attachment
part of the head guard is fitted onto the attachment part of the rear frame and the
screw member and fastened thereon by screwing a fixing bolt inserted through the bolt
inlet.
[0007] In this way, the fastening member is less exposed so as to prevent damage due to
collision and scratch against bolts and nuts, for instance, according to the above
described technique.
Citation List
Patent Literature
[0008] Patent Document 1: Japanese Unexamined Patent Application Pub. No.
2001-151490
SUMMARY
Technical Problem
[0009] Meanwhile, a head guard is required to have high rigidity, and thus includes thick
iron plate members integrated by welding joint. When the members are joined by welding,
a welding jig is used to arrange the shape and fix the members before welding. However,
residual strain occurs from welding and deformation occurs after removing the head
guard out from the jig.
[0010] Patent Document 1 discloses no technique for correcting misalignment that possibly
occurs from deformation due to welding of a head guard between a bolt inlet (attachment
hole) of the head guard side and a screw hole (attachment hole) of a metal piece.
[0011] Accordingly, the head guard and the piece member are screwed while elastically deforming
the head guard with high rigidity, which results in an increase in assembly workload
and cost. Also, since the head guard is forced to deform elastically, internal stress
rises and the strength decreases.
[0012] The present invention was made in view of the above issues. An object is to provide
an attachment structure for a forklift that absorbs deformation caused by welding
joint, so that quality is stably secured and assembly to a vehicle body is facilitated.
Solution to Problem
[0013] To achieve the above object, a head guard attachment structure according to the present
invention includes a head guard which includes: a pair of right and left front pillars
disposed at a front of a vehicle body of a forklift and arranged at an interval in
a vehicle width direction; a pair of right and left rear pillars disposed at a rear
of the vehicle body and arranged at an interval in the vehicle width direction; and
a ceiling part disposed over the front pillars and the rear pillars. A fastening direction
of fastening members which fasten either one of the pair of front pillars or the pair
of rear pillars to the vehicle body is the vehicle width direction, and a fastening
direction of fastening members which fasten other one of the pair of front pillars
or the pair of rear pillars to the vehicle body is a vehicle front-rear direction.
[0014] Further, preferably in the present invention, the fastening direction of the fastening
members attaching the front pillars to the vehicle body may be orthogonal to the fastening
direction of the fastening members attaching the rear pillars to the vehicle body,
as seen in a planar view.
[0015] Accordingly, the fastening direction of the fastening members attaching the head
guard to the vehicle body at the front pillars are orthogonal to the fastening direction
of the fastening members attaching the head guard to the vehicle body at the rear
pillars, as seen in a planar view. Thus, it possible to secure the degree of freedom
in two directions in fastening, which makes it possible to easily absorb the production
error of the head guard and to improve the assembly performance of the fastening members
to the vehicle body.
[0016] Further, preferably in the present invention, at least one of the pair of front pillars
or the pair of rear pillars is fastened to the vehicle body by interposing an attachment
bracket between the vehicle body and each front pillar or each rear pillar, and the
fastening direction of the fastening members fastening the bracket and each front
pillar or each rear pillar is the vehicle front-rear direction.
[0017] Upon attaching the front pillars and the rear pillars to the vehicle, the attachment
surface on the vehicle side can be used as a guide in the vehicle width direction.
According to the above invention, the attachment bracket can be used as a guide in
the vehicle front-rear direction, which makes it possible to facilitate the attachment.
[0018] Further, preferably in the present invention, the front pillars and the rear pillars
may each have a closed cross section in an orthogonal direction to an axis of each
pillar. The attachment bracket may contact an inner circumferential surface of the
front pillars and/or the rear pillars. A screw part to which each fastening member
is screwed may be disposed on a side of the bracket opposite to a side facing the
inner circumferential surface.
[0019] Accordingly, with the tip end of the screw member disposed inside one of the pillars,
the number of protrusions around the attachment part is reduced, which improves safety
during work.
[0020] Further, with the screw member disposed on the attachment bracket, fastening work
between the attachment bracket and the front pillars, and between the attachment bracket
and the rear pillars are facilitated.
[0021] Further, preferably in the present invention, the attachment bracket may be fixed
to a vehicle body frame supporting a counterweight of the forklift.
[0022] Accordingly, with the attachment bracket fixed to the vehicle body frame supporting
the counterweight of the forklift, it is possible to increase the rigidity of the
attachment part of the head guard and improve the protection effect of the head guard.
[0023] Further, preferably in the present invention, vehicle-side attachment parts attached
to the front pillars and the rear pillars may include inclined surfaces enlarged in
the vehicle width direction at lower sides, and the front pillars and the rear pillars
may each have inclined surfaces along the inclined surfaces of the vehicle-side attachment
parts.
[0024] According to the present invention, with the vehicle-side attachment parts attached
to the front pillars and the rear pillars including inclined surfaces enlarged in
the vehicle width direction at lower sides, and the front pillars and the rear pillars
having inclined surfaces along the inclined surfaces of the vehicle-side attachment
parts, the positions can be easily matched between the center line in the vehicle
width direction of the vehicle body and the center line in the vehicle width direction
of the head guard when the head guard is attached to the vehicle body, which makes
it possible to facilitate the assembly work.
Advantageous Effects
[0025] With the above configuration, the attachment structure is capable of absorbing the
deformation caused by the welding joint. Thus, provided is the head guard structure
of the forklift whereby stability of the quality is secured and attachment of the
vehicle is facilitated.
BRIEF DESCRIPTION OF DRAWINGS
[0026]
FIG. 1 is a schematic side view of a forklift according to one embodiment of the present
invention.
FIG. 2 is a schematic perspective view of attachment parts on a vehicle side and on
a head guard according to one embodiment of the present invention.
FIG. 3 is a schematic perspective view of the head guard according to the present
invention.
FIG. 4 is a detail view of an attachment part of the head guard to front pillars according
to the present invention.
FIG. 5 is a cross-sectional view taken along the line A-A from FIG. 4.
FIG. 6A is a detail view of an attachment part of a rear pillar in FIG. 2, and FIG.
6B is a diagram for describing fitting the rear pillar onto an attachment bracket.
FIG. 7A is a joint structure diagram between the attachment bracket and the rear pillar,
and the FIG. 7B is a view taken from FIG. 7A as seen in the direction of the arrow
A.
DETAILED DESCRIPTION
[0027] Embodiments of the present invention will now be described in detail with reference
to the accompanying drawings. It is intended, however, that unless particularly specified,
dimensions, materials, shapes, relative positions and the like of components described
in the embodiments shall be interpreted as illustrative only and not limitative of
the scope of the present invention.
[0028] FIG. 1 is a schematic side view of a forklift according to one embodiment of the
present invention, and the reference sign 1 indicates an overall side view of a forklift.
[0029] A forklift 1 includes a vehicle body 2, a load lifting unit 7 mounted to a front
part of the vehicle body 2, a head guard 5 mounted to an upper part of the vehicle
body 2, front wheels 8, rear wheels 9 mounted to the rear of the vehicle body 2, a
counterweight 3 mounted to the rear of the vehicle body 2, a steering wheel 6 for
steering the rear wheels 9, and a seat 10 for seating a driver. The head guard 5 is
to prevent a load from falling onto a driver's seat due to collapse of loads lifted
by the load lifting unit 7. The front wheels 8 are driving wheels for moving the forklift
1. The rear wheels 9 are steering wheels of the forklift 1. The counterweight 3 has
a weight such that the rear wheels 9 do not become spaced from the road surface due
to the weight of loads on the load lifting unit 7, and such that the rear wheels 9
can contact the road surface firmly.
[0030] Since the forklift 1 is steered by the rear wheels 9, the traveling direction of
the vehicle body 2 cannot be changed unless the rear wheels 9 are brought into firm
contact with the road surface by the counterweight 3.
[0031] The vehicle body 2 includes the vehicle body frame 21 on which an engine, a device
for driving the front wheels, a hydraulic pump such as a hydraulic cylinder, and a
device for driving and work such as a steering device for the rear wheels (not illustrated)
are mounted, and an engine cover 24 covering the top of these devices for traveling
and work.
[0032] The vehicle body frame 21, to which the head guard 5 is mounted, includes a pair
of right and left side frames (not illustrated), and a plurality of cross members
(not illustrated). The side frames each have a rectangular basic cross section in
the vehicle width direction, extending in the vehicle front-rear direction at an interval
in the vehicle width direction. The cross members connect the pair of right and left
side frames in the vehicle width direction and are arranged at an interval in the
front-rear direction.
[0033] The devices for traveling and devices for work are accommodated between the pair
of right and left side frames.
[0034] The engine cover 24 covers a space between the pair of right and left side frames.
[0035] A seat 10 for seating a driver is disposed on the upper surface of the engine cover
24.
[0036] The vehicle body frame 21 has high strength and high rigidity because the counterweight
3 or the like are connected to the vehicle body frame 21 via the cross members.
[0037] The load lifting unit 7 includes forks 72 having an L shape as seen from the side,
on which loads are to be placed, a back rest 73 to which the forks 72 are attached,
a mast 71 for supporting the back rest 73 slidably in the vertical direction, a lift
chain (not illustrated) for sliding the back rest 73 in the vertical direction, an
assist mast 75 that is fit slidably in the vertical direction to the mast 71 so as
to lift the back rest 73 further above the upper end of the mast 71, and a tilt cylinder
(hydraulic pressure) 76 for tilting the mast 71 and the assist mast 75 to adjust tips
of the forks 72. The tips of the forks 72 are tilted (adjusted) upward and downward
to insert the forks 72 under a load, so that the load is placed on the forks 72.
[0038] The assist mast 75 is slid by a lift cylinder (hydraulic pressure) that is not illustrated,
upward and downward with respect to the mast 71.
[0039] FIG. 2 illustrates the head guard in an attached state, and FIG. 3 is an exterior
perspective view of the head guard.
[0040] The head guard 5 includes a pair of right and left front pillars 51, 51 disposed
at the front of the vehicle body 2 so as to be spaced from each other in the vehicle
width direction, a pair of right and left rear pillars 52, 52 disposed at the rear
of the vehicle body 2 so as to be spaced from each other in the vehicle width direction,
and a rectangular ceiling 53 welded to the upper ends of the four pillars on the four
corners.
[0041] While the front and rear pillars are arranged in pairs, the same reference number
is used for each pair to simplify the description.
[0042] The front pillars 51 each have a pillar shape with a cross-section in an orthogonal
direction to the axis of the pillar forming a hollow closed cross section of a substantially
rectangular shape.
[0043] The lower parts of the front pillars 51 are attached to the front of the vehicle
body 2 of the forklift 1 and above the front wheels 8.
[0044] FIG. 4 illustrates details of the attachment structure of the lower parts of the
front pillars 51.
[0045] An attachment structure of the front pillars 51 adjacent to the vehicle body frame
21 includes a pair of right and left front-attachment brackets 21b standing on the
upper surface of a front fender 21a of the vehicle body frame 21, a pair of right
and left gussets 21c disposed on the inner sides of the front-attachment brackets
21b in the vehicle width direction so as to maintain the rigidity of the front-attachment
brackets 21b in the vehicle width direction, and an instrument panel 28 (see FIG.
1) connecting the pair of right and left gussets 21c, for instance. A steering wheel
6, a control lever for driving and lifting loads, driving meter devices and the like
are mounted to the instrument panel 28. An instrument reinforcement member for reinforcement
is disposed inside the instrument panel 28.
[0046] Thus, the pair of right and left front attachment brackets 21b has high rigidity
in the vehicle width direction, and also maintains high rigidity in the vertical direction
for being disposed on the front fender 21a integrally formed with the vehicle body
frame 21.
[0047] Further, the right and left front attachment brackets 21b each have a distal end
inclined toward the inside of the vehicle body 2, so as to have an inclined surface
of a trapezoidal shape as seen in the vehicle front-rear direction. This inclined
surface guides insertion from above when mounting the front pillars 51 to the front
attachment brackets 21b , and makes it possible to easily determine the positions
of the center lines in the vehicle width direction of the vehicle body 2 and the head
guard 5.
[0048] Thus, the lower end and the upper end of the head guard 5 respectively have a dimension
WL and a dimension WU in the vehicle width direction, satisfying a relationship of
WL > WU so as to conform to the inclined surface.
[0049] The front attachment brackets 21b each include the first attachment holes 21d penetrating
through in the vehicle width direction. Each nut 22d constitutes a fastening member
22 fixed to a position corresponding to the corresponding first attachment hole 21d,
on a side of the front attachment bracket 21b that is inside the vehicle. The nuts
22d are welded to the front attachment brackets 21b.
[0050] At the lower part of each front pillar 51, two second attachment holes 51a are disposed
in the vertical direction on a face facing the first attachment holes 21d.
[0051] The second attachment holes 51a are disposed so as to open on a surface contacting
the front attachment bracket 21b of the rectangular cross section.
[0052] Further, work holes 51b are disposed so as to open at the lower part of each front
pillar 51, and on a face of the rectangular cross section that is opposite to the
face on which the second attachment holes 51a are disposed. The work holes 51b each
have a diameter larger than that of the second attachment holes 51a.
[0053] Each work hole 51b has a diameter such that a bolt 22a, a spring washer 22b, and
a plain washer 22c, all of which constitute a fastening member 22, can pass through
the work hole 51b, and a box wrench (not illustrated) for fastening the bolt 22a can
pass through the work hole 51b.
[0054] Each front pillar 51 is fixed to the corresponding front attachment bracket 21b by
assembling the spring washer 22b and the plain washer 22c onto the bolt 22a being
a fastening member 22, and screwing the bolt 22a onto the nut 22d through the work
hole 51b.
[0055] Each work hole 51b is closed by a resin plug 23 after fastening the first bolt 22a.
[0056] The rear pillars 52 each have a pillar shape with a cross-section in an orthogonal
direction to the axis of the pillar forming a hollow closed cross section of a substantially
rectangular shape, similarly to the front pillars 51.
[0057] FIGs. 2, 6A and 6B illustrate an attachment structure of the lower parts of the rear
pillars 52 in detail.
[0058] An attachment structure of the rear pillars 52 adjacent to the vehicle body frame
21 includes a pair of right and left first support brackets 26 disposed at the rear
of the vehicle body of a forklift 1 and along an outer side in the vehicle width direction
of the upper surface 21e of the vehicle body frame 21, and a pair of right and left
second support brackets 27 extending upward from the vertical wall surface of the
inner sides of the vehicle body frame 21 in the vehicle width direction.
[0059] The first support brackets 26 each have a pillar shape with a substantially rectangular
cross section as seen in a planar view.
[0060] The rear surface of the pillar shape of the each first support bracket 26 is joined
to the front surface of a rear cross member (not illustrated), and arranged so that
the outer surfaces of the pillar shape are along the outer surfaces of the vehicle
body frame 21.
[0061] The rear pillars 52 of the head guard 5 are attached to rear attachment brackets
25. Each rear attachment bracket 25 is disposed and fixed over the upper parts of
the first support bracket 26 and the second support bracket 27.
[0062] As a result, the attachment part of at the lower part of each rear pillar 52 has
high rigidity with respect to the vertical direction, the front-rear direction, and
the right-left direction of the vehicle.
[0063] As illustrated in FIG. 6A and 6B, each rear attachment bracket 25 includes a flat
portion 25a disposed over the upper parts of the first support bracket 26 and the
second support bracket 27, a vertical wall portion 25c formed continuously from the
flat portion 25a and bended downward, and a protrusion 25a to which the rear pillar
52 is attached.
[0064] The vehicle outer edge 25cs and the lower edge 25cu of the vertical wall portion
25c are respectively fixed to the horizontal edge 26a and the vertical edge 26b of
the upper edge of the cutout section of the first support bracket 26.
[0065] Thus, the first support bracket 26 has a box shape structure.
[0066] The protrusion 25a is disposed so as to contact the front surface of the rectangular
cross section of the rear pillar 52.
[0067] The protrusion 25a includes the fourth attachment hole 25d penetrating through in
the vehicle front-rear direction disposed at a position corresponding to the third
attachment hole 52a of the rear pillar 52.
[0068] A nut 22d constituting a fastening member 22 is disposed in accordance with the axis
of the fourth attachment hole 25d at the opposite side to the face contacting the
rear pillar 52.
[0069] Further, the protrusion 25a includes a guide portion 25e inclined toward the rear
of the vehicle (or curved in an arc shape) at the distal end, so as to facilitate
fitting when the rear pillar 52 is fit onto the protrusion 25a.
[0070] Here, the inclining direction of the guide portion 25e is not limited to the above.
It is sufficient if the guide portion 25e is inclined to the opposite side from the
face contacting the inner circumferential surface of the rear pillar 52.
[0071] Further, while the rear attachment bracket 25 is joined to the rear pillar 52 in
the present embodiment, the same effect can be achieved when an attachment bracket
similar to the rear attachment bracket 25 is used to fix the front pillars 51.
[0072] Each rear pillar 52 is attached to the protrusion 25a as follows. The bolt 22a, to
which the spring washer 22b and the plain washer 22c are assembled and which constitutes
the fastening member 22, is inserted into the third attachment hole 52a of the rear
pillar 52 and screwed to the nut 22d fixed to the protrusion 25a.
[0073] In the present embodiment, each front pillar 51 is attached to the vehicle body 2
by inserting the bolt 22a in the vehicle width direction of the vehicle body 2.
[0074] When the front pillars 51 are attached to the vehicle body 2, each front pillar 51
has a degree of freedom in the vehicle width direction.
[0075] Thus, the deforming direction generated at a joint between each front pillar 51 and
the ceiling 53 by fastening the bolt 22a is different from the deforming direction
generated at a joint between each rear pillar 51 and the ceiling 53.
[0076] As a result, the production error in the dimension in the vehicle width direction
produced during production is easily absorbed (corrected) by fastening the bolt 22a,
which facilitates the attachment work.
[0077] On the other hand, each rear pillar 52 is attached to the vehicle body 2 by inserting
the bolt 22a in the vehicle front-rear direction of the vehicle body 2.
[0078] When the rear pillars 52 are attached to the vehicle body 2, each rear pillar 52
has a degree of freedom in the vehicle front-rear direction.
[0079] As a result, the production error in the dimension in the vehicle front-rear direction
produced during production is easily absorbed (corrected) by fastening the bolt 22a,
which facilitates the attachment work.
[0080] Described below is an example of advantages obtained during attachment of the head
guard 5 to the vehicle body 2 from the above structure of the present embodiment,
in which the bolts 22a are fastened in two directions orthogonal to each other.
[0081] First, each rear pillar 52 is fitted onto the protrusion 25, and the plain washer
22c and the spring washer 22b are mounted to the bolt 22a to temporarily fasten the
rear pillar 52 onto the nut 22d.
[0082] In the above state, the rear pillar 52 has a degree of freedom (a length TR from
temporal fastening and completed fastening, see FIG. 7) in the direction of the axis
of the bolt 22a, which is the vehicle front-rear direction.
[0083] That is, absorption of the production error in dimension is facilitated at TL1 and
TL2 in FIG. 3.
[0084] Next, each front pillar 51 is temporarily fastened to the nut 22d by mounting the
plain washer 22c and the spring washer 22b onto the bolt 22a.
[0085] In a case where the front pillar 51 is temporarily fastened to the first nut 22,
it is possible to produce an adjustment margin corresponding to the temporarily fastened
length TR of the rear pillar 52 and a gap (TR = D1-D2, see FIG. 5) between the second
attachment hole 51a and the outer circumference of the screw portion of the bolt 22a.
[0086] Thus, it is possible to easily perform the temporal fastening of the front pillar
51 onto the vehicle body 2 via the bolt 22a only by adjusting the position of the
front pillar 51 in the vehicle width direction.
[0087] Subsequently, the head guard 5 is easily attached by completely fastening one of
the bolts.
[0088] Further, since the attachment of the head guard 5 to the vehicle body 2 is facilitated,
the assembly workload required for the attachment is reduced, which makes it possible
to achieve a cost-reduction effect.
[0089] In the present embodiment, a part of the vehicle body 2 to which the front pillars
51 and the rear pillars 52 are mounted is formed in a trapezoidal shape, with the
upper side slightly narrower than the lower side in the vehicle width direction. In
this way, attachment of the front pillars 51 and the rear pillars 52 to the vehicle
body 2 is even more facilitated, and matching of the centers of the vehicle body 2
and the head guard 5 in the vehicle front-rear direction is facilitated, which makes
it possible to improve the quality of the products.
[0090] Further, while each rear pillar 52 is attached to the protrusion 61 by a single bolt
22a in the present embodiment, using two or more bolts 22a enhances the fastening
rigidity between the rear pillars 52 and the protrusion 61 and restricts the deformation
of the head guard 5 in the vehicle width direction, which makes it possible to improve
the stability of the quality and strength.
Industrial Applicability
[0091] The present invention can be provided as an attachment structure for attaching a
head guard to a vehicle body of a forklift.
Reference Signs List
[0092]
- 1
- Forklift
- 2
- Vehicle body
- 3
- Counterweight
- 5
- Head guard
- 6
- Steering wheel
- 7
- Load lifting unit
- 8
- Front wheel
- 9
- Rear wheel
- 21
- Vehicle body frame
- 21b
- Front attachment bracket
- 21d
- First attachment hole
- 22
- Fastening member
- 22a
- Bolt
- 22b
- Spring washer
- 22c
- Plain washer
- 23
- Plug
- 25
- Rear attachment bracket
- 25a
- Protrusion
- 25d
- Fourth attachment hole
- 51
- Front pillar
- 51a
- Second attachment hole
- 51b
- Work hole
- 52
- Rear pillar
- 52a
- Third attachment hole