JP4748961B2 - Lift truck - Google Patents

Description

  The present invention relates to a mounting structure for a load wheel of a lift truck such as a rack fork having a three-way fork, for example.

  2. Description of the Related Art Conventionally, there is a lift truck provided with a three-way fork capable of performing left and right and front cargo handling as described in, for example, Patent Documents 1 and 2 below. This type of lift truck is generally referred to as a three-way rack forklift or a three-way stacking truck. Drive tires and caster tires are provided at the bottom of the body of the lift truck. A pair of straddle legs extend forward from both lower sides of the vehicle body, and a road wheel is rotatably attached to the end of each straddle leg via a shaft. A pair of left and right masts are erected in front of the vehicle body, and a lift bracket is supported by the mast so as to be movable up and down, and a shift bracket is supported by the lift bracket so as to be capable of shifting (horizontal movement) in the horizontal direction of the vehicle body. . A pair of forks for handling cargo is supported at the front end of the shift bracket so as to be able to turn 180 ° to the left and right of the vehicle body.

  In the above configuration, the lift truck travels in the front-rear direction by rotating the drive tire and rolling the drive tire, the caster tire, and the road wheel on the floor. Further, by changing the direction of the drive tire while rotating the drive tire, the lift truck turns in the left-right direction. When carrying out cargo handling, move the lift truck to the passage between the storage shelves installed in parallel and stop it at a predetermined position, then shift the shift bracket and turn the fork to move the fork to one side Opposite the storage shelf. If the load is already loaded on the fork, the fork is made to face the storage shelf on one side by shifting the shift bracket and turning the fork before the lift truck enters the passage. Then, the lift bracket is moved up and down along the mast so that the fork faces the predetermined storage space of the storage shelf, and then the shift bracket is shifted to insert the fork into the storage space and place it on the fork. The loaded luggage is loaded into the storage space and carried in, or the luggage stored in the storage space is unloaded with a fork.

  In this way, when loading or unloading a load with a fork in the storage space, about two thirds of the weight of the lift truck body and the weight of the load is placed on the load wheel attached to the end of one straddle leg. Take it. For this reason, conventionally, as shown in FIGS. 11 to 13, two load wheels 55 are provided at the end of each straddle leg 52 so that the load can be stably loaded or loaded even when a certain amount of weight is applied. A structure in which a pair of shafts 56 and a pair of carrier plates 57 are attached in a front-and-rear direction has been employed (see Patent Documents 1 and 2).

  In the mounting structure as described above, the turning center of the vehicle body 51 when turning the lift truck 50 by changing the direction of the drive tire 53 is an axis passing through the middle of the front and rear road wheels 55 as shown in FIG. , Called swivel axis.) Located on CL. For example, as shown in FIG. 11, when the lift truck 50 turns to the right, the turning center of the vehicle body 51 is located on the turning axis CL near the right road wheel 55. Further, as shown in FIG. 12, a straight line ML connecting the centers M1 and M2 of the road wheels 55 is orthogonal to the turning axis CL. Further, when turning, the two-wheel road wheel 55 on the turning side (right side in FIG. 11) functions as a thrust that prevents the vehicle body 51 from falling to the turning side. Specifically, as shown in FIG. 13, the intersection T between the straight line ML connecting the centers M1 and M2 of the right road wheel 55 of the vehicle body 51 and the turning axis CL, and the center M3 of the drive tire 53 (shown in FIG. 11). The portions of the two road wheels 55 (the portions indicated by the oblique lines) located outside the vehicle body 51 from the straight line RL connecting the two function as stretches.

JP 2000-7294 A JP 2004-35231 A

  However, when the straight line ML connecting the centers M1 and M2 of each road wheel 55 is orthogonal to the turning axis CL as in the conventional mounting structure, for example, when the lift truck 50 turns to the right as shown in FIG. As shown in FIG. 12, when the turning center Q of the vehicle body 51 is located at the intersection T between the straight line ML and the turning axis CL, the front load wheel 55 slides to the right as indicated by the arrow and The road wheel 55 turns as it slides to the left as indicated by the arrow. For this reason, a large force (rotational force of the drive tire 53) is required to complete the turn, which causes adverse effects such as an increase in power consumption of the lift truck 50. Further, a large shearing stress is applied to each road wheel 55, and the life of the mounting parts such as the road wheel 55 and the shaft 56 is shortened. Furthermore, the frictional noise between the road wheel 55 and the floor surface is increased, and an irritating and unpleasant sound is generated for the user.

  The present invention solves the above-mentioned problems, and the problem is that the force required for turning is reduced, the stress applied to the road wheel is reduced, and the friction noise between the road wheel and the floor surface is suppressed. An object of the present invention is to provide a lift truck capable of achieving the above.

In the present invention, a pair of straddle legs extends forward from both lower sides of the vehicle body, a pair of side plates are fixed to the front end portions of the straddle legs, and the end plates are fixed to the front ends of the pair of side plates. In the lift truck in which a frame is formed and a pair of front and rear road wheels are rotatably mounted via shafts in the frame, each shaft of the pair of load wheels is connected to a pair of carrier plates, and each carrier The plate is formed with two insertion holes for inserting the respective shafts and steps provided in parallel with the insertion direction of the respective shafts. by but which connects the respective through holes in the respective shaft and each carrier plate by inserting the respective axes so as to face, the lateral direction of the center of each load wheel body As, attach each road wheel in the frame.

  If the center of each road wheel is shifted in the left-right direction of the vehicle body as described above, the straight line connecting the center of each road wheel will not be orthogonal to the turning axis, so the turning center of the vehicle body will turn when the lift truck turns. At any point on the shaft, at least one of the load wheels turns while rotating. For this reason, the force required for turning can be reduced, and there is no adverse effect such that the power consumption of the lift truck is increased. Further, the stress applied to the road wheel can be reduced, and the life of the mounting parts such as the road wheel and the shaft is prolonged. Furthermore, the frictional noise between the road wheel and the floor can be reduced, and the user is not uncomfortable.

  In the present invention, the center of the rear road wheel is shifted from the center of the front road wheel toward the center of the vehicle body.

  When the straight line connecting the centers of the road wheels is orthogonal to the turning axis as in the conventional mounting structure described above, that is, when the two road wheels are arranged in parallel with the longitudinal direction of the vehicle body, the lift truck is When turning, as shown in FIG. 13, in the two-wheel road wheel on the turning side, the rear load wheel has a larger area than the front load wheel. The road wheel is easier to wear than the front road wheel and has a shorter life. However, when the road wheels are arranged by shifting the center of the rear road wheel to the center side of the vehicle body from the center of the front road wheel as in the present invention, the lift truck is on the turning side when turning. In a two-wheel road wheel, the rear road wheel and the front road wheel have substantially the same area, and the two road wheels can be evenly stretched. The road wheel is not more easily worn than the front road wheel, and the service life is not shortened.

  According to the present invention, by attaching each road wheel in the frame so that the centers of the pair of front and rear road wheels are displaced in the left-right direction of the vehicle body, the straight line connecting the centers of the road wheels is not orthogonal to the turning axis. Therefore, when turning the vehicle body, no matter where the turning center is located on the turning axis, at least one road wheel turns while rotating, reducing the force required for turning and the stress applied to the road wheel It is possible to reduce the friction noise between the road wheel and the floor surface.

  1 and 2 are views showing the structure of a lift truck according to an embodiment of the present invention. FIG. 1 is a side view of the lift truck, and FIG. 2 is a plan view of the lift truck. In each figure, 100 is a lift truck. The lift truck 100 is a manned three-way rack forklift equipped with a three-way fork capable of handling left and right and front. Sometimes referred to as a three-way stacking track. A drive tire 3 and caster tire 4 are provided at the bottom of the vehicle body 1 of the lift truck 100. A pair of straddle legs 2 extend forward from both lower sides of the vehicle body 1, and a pair of front and rear load wheels 5 are rotatably attached to the front ends of the straddle legs 2 via shafts 6. . An outer mast 7 is erected in front of the vehicle body 1, and an inner mast 8 is fitted inside the outer mast 7 so as to be movable up and down with respect to the outer mast 7. A lift bracket 9 is supported by the inner mast 8 so as to be movable up and down, and a shift bracket 10 can be shifted (horizontally moved) in the left-right direction of the vehicle body 1 as indicated by a two-dot chain line in FIG. It is supported by. A pair of forks 11 for handling cargo is supported at the front end of the shift bracket 9 so as to be able to turn 180 ° to the left and right of the vehicle body 1 as indicated by a two-dot chain line in FIG. A driver's seat 12 on which an operator is boarded is provided at the upper portion of the vehicle body 1, and an operation unit 13 including a lever, a handle, and the like for the operator to operate each part of the lift truck 100 is provided in the driver's seat 12. Yes.

  In the above-described configuration, the drive tire 3 is rotated by driving a travel motor (not shown), and the drive tire 3, the caster tire 4, and the road wheel 5 are rolled on the floor, whereby the lift truck 100 is Drive in the front-rear direction. Further, by changing the direction of the drive tire 3 by driving a steering motor (not shown) while rotating the drive tire 3, the lift truck 100 turns left and right. When carrying out cargo handling, the lift truck 100 is moved to a passage between storage shelves (not shown) installed in parallel and stopped at a predetermined position, and then the shift bracket 10 is shifted and the fork 11 is turned. By causing the fork 11 to face the storage shelf on one side. The lift bracket 9 is moved up and down along the masts 7 and 8 so that the fork 11 faces a predetermined storage space (not shown) of the storage shelf. A baggage (not shown) inserted into the storage space and loaded on the fork 11 is loaded into the storage space and carried in, or a baggage (not shown) stored in the storage space is loaded with the fork 11. Unload and unload.

  3-7 is a figure which shows the attachment structure of the road wheel 5. As shown in FIG. In each drawing, the mounting structure of the road wheel 5 on the left side (lower side in FIG. 2) of the vehicle body 1 of the lift truck 100 is shown. 3 is a plan view of the structure, FIG. 4 is a left side view of the structure, FIG. 5 is a right side view of the structure, FIG. 6 is a sectional view of the structure viewed from the front, and FIG. 7 is an exploded perspective view of the structure. FIG.

  As shown in FIG. 3, a pair of side plates 15 and 16 are fixed to the side surface of the front end portion of the straddle leg 2 by welding, and the end plate 17 is fixed to the front end of each side plate 15 and 16 by welding. A frame 14 is formed at the tip of the straddle leg 2. The black-colored portion indicates the welding location between the members. As shown in FIGS. 4, 5, and 7, the side plates 15, 16 are formed with substantially horizontally long fitting grooves 15 a, 16 a that open downward. A cover plate 18 is fixed to the side surface outside the frame 14 of the outer side plate 15 by welding so as to cover the entire insertion groove 15a, and the insertion groove 16a is formed at the lower side surface outside the frame 14 of the inner side plate 16. One end of the horizontal plate 20 is fixed so as to partially cover. The other end of the horizontal plate 20 is fixed to the lower side of the outer side of the frame of the inner side plate (not shown) fixed to the straddle leg 2 on the right side of the vehicle body 1.

  A block 19 is fixed to the side surface of the side plate 16 outside the frame 14 and the upper surface of the horizontal plate 20 by welding. A screw hole 19a for screwing the set screw 33 is formed in the block 19 so as to communicate with the fitting groove 16a. A beam 21 is fixed by welding at the center of the side surface inside the frame 14 of the side plates 15 and 16. Moreover, the stopper 30 is being fixed to the side surface upper part inside the frame 14 of the both-sides plates 15 and 16, and the side surface of the beam 21 by welding, respectively. The stopper 30 is formed with a through hole 30a that allows the sleeve 31 with the flange to freely pass therethrough. Bolts 35 are loosely inserted into the sleeve 31 and are held via washers 36 and spring washers 37. A bracket 22 is fixed to the outer side plate 15 and the end plate 17 with screws 23, and a guide roller 24 is rotatably supported on the bracket 22 via a shaft 25.

  As shown in FIG. 3, a pair of front and rear road wheels 5 are located in the frame 14, and the center M2 of the rear (the straddle leg 2 side) road wheel 5 is the center of the front (end plate 17 side) road wheel 5. It is provided so as to be shifted by a distance Y toward the center SL (shown in FIG. 8) side (upper side in FIG. 3) of the vehicle body 1 parallel to the left-right direction of the vehicle body 1 with respect to M1. An axis CL passing through the middle of the two road wheels 5 in FIG. 3 is a turning axis at which the turning center of the vehicle body 1 is located when the lift truck 100 is turned. Each load wheel 5 is rotatably mounted on a shaft 6 via a bearing 26, and each shaft 6 is connected to a pair of carrier plates 27.

  As shown in FIG. 7, each carrier plate 27 includes two insertion holes 27 a for inserting the respective shafts 6, and slits 27 b reaching from the respective insertion holes 27 a to the front surface or the rear surface parallel to the insertion direction of the shaft 6. , A screw hole 27c reaching from the lower surface parallel to the insertion direction of the shaft 6 to a position passing through the slit 27b, a step 27d provided in parallel to the insertion direction of the shaft 6, and a screw hole 27e for screwing the bolt 35 are formed. Has been. Each shaft 6 is inserted into each insertion hole 27a so that the high surface and the low surface of the step 27d of each carrier plate 27 face each other, and each load wheel 5, each washer 28, and each carrier plate 27 are spaced from each other. Adhering to prevent the occurrence of Then, when the screws 29 are screwed into the screw holes 27c in this tight contact state, the slits 27b are closed, the insertion holes 27a are narrowed, and the shafts 6 are connected to the carrier plates 27. . In this state, the centers M1 and M2 (shown in FIG. 3) of each road wheel 5 are shifted in the axial direction of the shaft 6 (direction parallel to the shaft 6). The length of each shaft 6 is set to be short so that both ends do not protrude from each carrier plate 27 in a state where each shaft 6 is connected to each carrier plate 27 as described above.

  Each carrier plate 27 connected to each shaft 6 as described above is loosely inserted into the insertion grooves 15a and 16a of the side plates 15 and 16 from below as shown in FIGS. The bolts 35 screwed into the screw holes 27e of the carrier plates 27 are supported so as to be suspended from the stoppers 30. Each carrier plate 27 can swing up and down with a protrusion 15b, 16b formed at the center of the upper surface of each insertion groove 15a, 16a as a fulcrum. The cross-hatched portions in FIGS. 3 and 7 indicate contact portions between the carrier plates 27 and the protrusions 15b and 16b. That is, by supporting each carrier plate 27 as described above, each load wheel 5 is mounted in the frame 14 so as to be swingable up and down.

  A set screw 33 is screwed into the screw hole 19a of the block 19 from the outside of the frame 14, and the carrier plate 27 on the side plate 16 side is moved to the side plate 15 side at the tip of the set screw 33 as shown in FIGS. Pressing. Further, a lock nut 34 is screwed onto the set screw 33 to prevent loosening. That is, as described above, the carrier plate 27 on the side plate 16 side is pressed toward the side plate 15, so that the assembly (assembly: ASSY) of the load wheel 5, the shaft 6 and the carrier plate 27 is pressed against the cover plate 18. Thus, the shaft 6 does not move in the axial direction.

  As described above, when the road wheels 5 are mounted in the frame 14 so that the centers M1 and M2 of the front and rear road wheels 5 are shifted in the left-right direction of the vehicle body 1, as shown in FIG. The straight line ML connecting the centers M1 and M2 is not orthogonal to the turning axis CL. Therefore, for example, when the lift truck 100 turns to the right as shown in FIG. 8, the turning center Q of the vehicle body 1 is a straight line in the vicinity of the right road wheel 5 of the vehicle body 1 as shown in FIG. When located at the intersection T between ML and the turning axis CL, each road wheel 5 turns while slightly rotating. Further, as shown in FIG. 9B, when the turning center Q of the vehicle body 1 is located at the intersection of the straight line ML1 passing through the center M1 of the front road wheel 5 and the front-rear direction and the turning axis CL, The front road wheel 5 slides rightward as indicated by an arrow, and the rear road wheel 5 turns while slightly rotating. Furthermore, as shown in FIG. 9 (c), when the turning center Q of the vehicle body 1 is located at the intersection of the straight line ML2 passing through the center M2 of the rear road wheel 5 and the longitudinal direction and the turning axis CL. The front road wheel 5 rotates slightly and the rear road wheel 5 turns while sliding sideways to the left as indicated by the arrow.

  In other words, the straight line ML connecting the centers M1 and M2 of each road wheel 5 is no longer orthogonal to the turning axis CL, so that when the lift truck 100 turns, the turning center Q of the vehicle body 1 is on any turning axis CL. Even at the point, at least one of the road wheels 5 turns while rotating. As a result, the force required for turning can be reduced, and there will be no adverse effects such as the power consumption of the lift truck 100 becoming intense. Further, the stress applied to the road wheel 5 can be reduced, and the life of the mounting parts such as the road wheel 5 and the shaft 6 is prolonged. Furthermore, the friction sound between the road wheel 5 and the floor surface can be reduced, and the user is not uncomfortable.

  For example, as shown in FIG. 8, when the lift truck 100 turns to the right, the two-wheel road wheel 5 on the turning side (right side in FIG. 8) prevents the vehicle body 1 from falling sideways to the turning side. Function as. Specifically, as shown in FIG. 10, the intersection T between the straight line ML connecting the centers M1 and M2 of the right road wheel 5 of the vehicle body 1 and the turning axis CL, and the center M3 of the drive tire 3 (shown in FIG. 8). The portions of the two road wheels 5 (portions indicated by diagonal lines) located on the outer side of the vehicle body 1 with respect to the straight line RL connecting the two function as stretches.

  11 to 13, the straight line ML connecting the centers M1 and M2 of each road wheel 55 is orthogonal to the turning axis CL, that is, the two road wheels 55 are in the longitudinal direction of the vehicle body 51. When the lift truck 50 turns, when the lift truck 50 turns, in the two-wheel road wheel 55 on the turning side, as shown in FIG. The area becomes larger than the stretched portion of the front load wheel 55. For this reason, the rear road wheel 55 is more easily worn than the front road wheel 55 and has a shorter life.

  However, as described above, when each road wheel 5 is arranged by shifting the center M2 of the rear road wheel 5 to the center SL (FIG. 8) side of the vehicle body 1 from the center M1 of the front road wheel 5, FIG. 10, in the two-wheel road wheel on the turning side, the projecting portion of the rear load wheel 5 and the projecting portion of the front load wheel 5 have substantially the same area. The vehicle body 1 can be prevented from falling down by being stretched evenly. Therefore, unlike the conventional mounting structure, the rear side load wheel 5 is not easily worn away than the front side road wheel 5, and the service life is not shortened.

  In the embodiment described above, an example in which the road wheels 5 are arranged so that the centers M1 and M2 of the front and rear road wheels 5 are shifted by the interval Y in the left-right direction of the vehicle body 1 is described. The interval may be larger or smaller than the interval Y. Increasing the deviation interval makes it easier to rotate each road wheel when the lift truck turns. Decreasing the deviation interval eliminates the need to increase the width of the frame to which each road wheel is attached and reduces the overall vehicle width. be able to.

  Further, in the embodiment described above, the present invention is applied to a three-way rack forklift. However, the present invention includes a forklift that can perform cargo handling only in the front, and a fork and a driver's seat in front of the vehicle body. The present invention can also be applied to a lift truck such as a forklift capable of performing a provided picking operation.

It is a side view of the lift truck concerning the embodiment of the present invention. It is a top view of the lift truck. It is a top view of the attachment structure of the load wheel of the lift truck. It is a left view of the mounting structure of the load wheel of the lift truck. It is a right view of the mounting structure of the load wheel of the lift truck. It is sectional drawing of the attachment structure of the load wheel of the lift truck. It is a disassembled perspective view of the attachment structure of the load wheel of the lift truck. It is a figure which shows the example of turning of the lift truck. It is a figure which shows the road wheel at the time of turning of the lift truck. It is a figure which shows the road wheel at the time of turning of the lift truck. It is a figure which shows the example of turning of the conventional lift truck. It is a figure which shows the road wheel at the time of turning of the conventional lift truck. It is a figure which shows the road wheel at the time of turning of the conventional lift truck.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle body 2 Straddle leg 5 Road wheel 6 Axis 14 Frame 15, 16 Side plate 17 End plate 100 Lift truck M1, M2 Center of road wheel SL Center of vehicle body

Claims (2)

A pair of straddle legs are extended forward from both lower sides of the vehicle body, a pair of side plates are fixed to the end portions of the straddle legs, and the end plates are fixed to the end portions of the pair of side plates so as to be framed. In a lift truck in which a pair of front and rear load wheels are rotatably mounted via shafts in the frame,
Each shaft of the pair of load wheels is connected to a pair of carrier plates, and each carrier plate has two insertion holes for inserting the shafts, and a step provided in parallel with the insertion direction of the shafts. And connecting each axis and each carrier plate by inserting each axis through each insertion hole so that the high and low surfaces of each carrier plate face each other. The lift truck is characterized in that the road wheels are mounted in the frame so that the centers of the road wheels are shifted in the left-right direction of the vehicle body. The lift truck according to claim 1.
A lift truck, wherein the center of the rear road wheel is shifted to the center of the vehicle body from the center of the front road wheel.

Images