EP2927184B1

EP2927184B1 - Forklift head-guard attachment structure

Info

Publication number: EP2927184B1
Application number: EP12889162.9A
Authority: EP
Inventors: Akihiro Ishigami; Tomoyuki Hayakawa
Original assignee: Mitsubishi Nichiyu Forklift Co Ltd
Current assignee: Mitsubishi Logisnext Co Ltd
Priority date: 2012-11-29
Filing date: 2012-11-29
Publication date: 2020-04-01
Anticipated expiration: 2032-11-29
Also published as: CN104540771A; BR112015006791A2; BR112015006791B1; JP5885319B2; EP2927184A4; JPWO2014083660A1; WO2014083660A1; EP2927184A1; CN104540771B

Description

TECHNICAL FIELD

The present invention relates to a head guard structure for a forklift.

BACKGROUND

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.
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.
Patent Document 1 discloses an attachment structure of a head guard.
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.
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.
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

Patent Document 1: Japanese Unexamined Patent Application Pub. No. 2001-151490
JP H07 206396 A describes a head guard structure for forklift having two front pillars and two rear pillars. There is a sealing part disposed over the front and rear pillars.
NL 6 509 863 A describes a head guard structure for an agriculture vehicle having front pillars and rear pillars. The fastening direction of the fastening members of the front pillars is in front-rear direction. At the rear pillars there are brackets having a fastening direction in vertical direction.
US 2805887 A describes a tractor canopy guard with an attachment structure which is installed on a tractor affording adequate protection for the operator.

SUMMARY

Technical Problem

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.
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.
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.
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

The object is solved by the features of the independent claims. Preferred embodiments are given in the dependent claims.
A head guard attachment structure 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.
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.
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.
Further, , 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.
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.
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.
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.
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.
Further, the attachment bracket is fixed to a vehicle body frame supporting a counterweight of the forklift.
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.
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.
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

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

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

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.
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.
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.
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.
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.
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.
The devices for traveling and devices for work are accommodated between the pair of right and left side frames.
The engine cover 24 covers a space between the pair of right and left side frames.
A seat 10 for seating a driver is disposed on the upper surface of the engine cover 24.
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.
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.
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.
FIG. 2 illustrates the head guard in an attached state, and FIG. 3 is an exterior perspective view of the head guard.
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.
While the front and rear pillars are arranged in pairs, the same reference number is used for each pair to simplify the description.
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.
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.
FIG. 4 illustrates details of the attachment structure of the lower parts of the front pillars 51.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Each work hole 51b is closed by a resin plug 23 after fastening the first bolt 22a.
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.
FIGs. 2, 6A and 6B illustrate an attachment structure of the lower parts of the rear pillars 52 in detail.
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.
The first support brackets 26 each have a pillar shape with a substantially rectangular cross section as seen in a planar view.
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.
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.
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.
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.
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.
Thus, the first support bracket 26 has a box shape structure.
The protrusion 25a is disposed so as to contact the front surface of the rectangular cross section of the rear pillar 52.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
That is, absorption of the production error in dimension is facilitated at TL1 and TL2 in FIG. 3.
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.
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.
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.
Subsequently, the head guard 5 is easily attached by completely fastening one of the bolts.
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.
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.
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

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

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

Claims

A head guard attachment structure, comprising a head guard (5) which includes:
a pair of right and left front pillars (51, 51) disposed at a front of a vehicle body (2) of a forklift (1) and arranged at an interval in a vehicle width direction;

a pair of right and left rear pillars (52, 52) disposed at a rear of the vehicle body (2) and arranged at an interval in the vehicle width direction; and

a ceiling part (53) disposed over the front pillars (51) and the rear pillars (52),

characterized in that

a fastening direction of fastening members (22) which fasten either one of the pair of front pillars (51) or the pair of rear pillars (52) to the vehicle body (2) is the vehicle width direction, and a fastening direction of fastening members (22) which fasten other one of the pair of front pillars (51) or the pair of rear pillars (52) to the vehicle body (2) is a vehicle front-rear direction,

wherein at least one of the pair of front pillars (51) or the pair of rear pillars (52) is fastened to the vehicle body (2) by interposing an attachment bracket (25) between the vehicle body (2) and each front pillar (51) or each rear pillar (52), wherein the fastening direction of the fastening members (22) fastening the attachment bracket (25) and each front pillar (51) or each rear pillar (52) is the vehicle front-rear direction.
The head guard attachment structure according to claim 1, wherein the fastening direction of the fastening members (22) attaching the front pillars (51) to the vehicle body (2) is orthogonal to the fastening direction of the fastening members (22) attaching the rear pillars (52) to the vehicle body (2), as seen in a planar view.
The head guard attachment structure according to claim 1 or 2, wherein the front pillars (51) and the rear pillars (52) each have a closed cross section in an orthogonal direction to an axis of each pillar,
wherein the attachment bracket (25) contacts an inner circumferential surface of the front pillars (51) and/or the rear pillars (52), and
wherein a screw part (22d) to which each fastening member (22) is screwed is disposed on a side of the bracket (25) opposite to a side facing the inner circumferential surface.
The head guard attachment structure according to claim 1, 2 or 3, wherein the attachment bracket (25) is fixed to a vehicle body frame (21) supporting a counterweight (3) of the forklift (1).
The head guard attachment structure according to any one of claims 1 to 4, wherein the attachment bracket (25) attached to the front pillars (51) and the rear pillars (52) include inclined surfaces enlarged in the vehicle width direction at lower sides, and
wherein the front pillars (51) and the rear pillars (52) each have inclined surfaces along the inclined surfaces of the attachment bracket (25.