JP2019085235A - forklift - Google Patents

Abstract

To provide a forklift capable of reducing stress generated in a mast.SOLUTION: In a forklift including a pair of masts 13 erected on a front part of a vehicle body, an energy absorbing member 40 absorbing a displacement energy generated in accordance with the deformation of the masts 13 is provided in the masts 13. When external force is applied to the vehicle body, the displacement energy caused by the inclination generated in the masts 13 in the back-and-forth direction or in the right-and-left direction is converted into the displacement energy of the energy absorbing member 40 to be absorbed depending on the application of the external force so that the stress generated in the masts 13 can be reduced and the deformation amount of the masts 13 can be reduced.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a forklift provided with a mast.

  For example, as disclosed in Patent Document 1, the forklift includes a pair of masts erected at the front of the vehicle body, and a lift bracket is supported by the pair of masts so as to be able to move up and down. Each of the pair of masts has an outer mast and an inner mast disposed inside the outer mast. Further, the lift bracket is attached with a fork for loading the load.

JP, 2009-57161, A

  By the way, when the forklift is traveling with the load placed on the fork, an impact is applied to the vehicle body as an external force, for example, when crossing over the step. At this time, the mast may be deformed such as tilting in the front-rear direction or the left-right direction or twisting, and the stress generated by the deformation may damage the mast.

  An object of the present invention is to provide a forklift capable of reducing the stress generated on the mast.

  A forklift for solving the above problems is a forklift comprising a pair of masts erected at the front of a vehicle body, the energy absorbing member absorbing the displacement energy generated in the mast as the mast is deformed. The gist is to prepare for the mast.

  According to this, when an external force is applied to the vehicle body, the mast is deformed to be inclined in the front-rear direction or the left-right direction according to the way of the external force. With the deformation of the mast, displacement energy is generated in the mast, which is converted into displacement energy of the energy absorbing member and absorbed. As a result, the stress generated on the mast can be reduced, and the amount of deformation of the mast can be reduced.

  Further, since the mast is made of metal, it is elastically deformed when an external force is applied, and periodic vibration occurs. However, the energy absorbing member converts the displacement energy of the mast into thermal energy and absorbs the heat to generate a damping force, thereby reducing the stress generated on the mast while rapidly converging the periodic vibration of the mast. Therefore, when displacement energy is generated in the mast due to the external force, the stress generated in the mast can be reduced by using the energy absorbing member as compared with the case where all the displacement energy is left as displacement energy of the mast.

In the forklift, the energy absorbing member may be a damper installed in a state of being bridged over the pair of masts.
According to this, it is possible to reduce the stress generated on the mast by absorbing part of the displacement energy by the damper. In addition, the energy absorbing member can be easily configured.

  In the forklift, the damper includes a piston rod capable of moving in and out of an outer cylinder, and a piston connected to the piston rod in the outer cylinder, and the piston is a fluid sealed in the outer cylinder. And an end portion side of the outer cylinder which is one axial end of the damper is disposed on one of the mast sides, and a protruding end side of the piston rod from the outer cylinder is the other. It may be disposed on the mast side.

  According to this, when a pair of mast receives external force and a mast deform | transforms, a piston rod follows a deformation | transformation of a mast and pops in and out with respect to an outer cylinder. By converting the displacement energy generated by the deformation of the mast into the displacement energy due to the movement of the piston rod and absorbing it, the stress generated on the mast can be reduced and the deformation amount of the mast can be reduced. Further, when the piston moves with the movement of the piston rod, the fluid sealed in the outer cylinder passes through the throttle. The resistance generated when the fluid passes through the throttle converts the kinetic energy of the piston rod into thermal energy and absorbs it to generate a damping force, which quickly converges the periodic vibration of the mast while causing stress on the mast Can be reduced. Therefore, the stress generated on the mast can be reduced by absorbing part of the displacement energy by the damper.

Further, the forklift may be provided with a pair of the dampers, and the pair of dampers may be installed in a state of being hooked on the pair of masts.
According to this, when twisting occurs in which the pair of masts are displaced relative to each other, each damper follows the twisting of each mast to cause the piston rod to appear and retract, thereby reducing the deformation amount of each mast Converge the vibration. Therefore, the pair of dampers can suppress the relative displacement of the pair of masts.

In addition, in the forklift, it is preferable that the pair of dampers be disposed apart from each other in the front-rear direction.
According to this, it is possible to prevent the pair of dampers from interfering with each other when twisting occurs in which the pair of masts is relatively displaced.

  In the forklift, the energy absorbing member includes a fluid pressure cylinder installed in a state of bridging over the pair of masts, and a pair of pressure action chambers defined by pistons accommodated in a cylinder tube of the fluid pressure cylinder. A fluid pipe connected to each, a tank connected to the fluid pipe, and a throttle for adjusting a flow passage cross-sectional area of the fluid pipe, wherein the fluid pressure cylinder can be inserted into and withdrawn from the cylinder tube The piston rod is connected to the piston, and the end of the cylinder tube which is an axial end of the fluid pressure cylinder is disposed on one of the mast sides, and the piston rod side is the other of the masts It may be arranged on the side.

  According to this, when a pair of masts receives external force and a mast deform | transforms, a piston rod follows a deformation | transformation of a mast and pops in and out with respect to a cylinder tube. By converting the displacement energy generated by the deformation of the mast into the displacement energy due to the movement of the piston rod and absorbing it, the stress generated on the mast can be reduced and the deformation amount of the mast can be reduced. Also, when the piston moves as the piston rod moves in and out, the fluid in the pressure application chamber compressed by the piston passes through the throttle via the fluid pipe and is discharged to the tank. The resistance generated when the fluid passes through the throttle converts the kinetic energy of the piston rod into thermal energy and absorbs it to generate a damping force, which quickly converges the periodic vibration of the mast while causing stress on the mast Can be reduced.

In the forklift, the energy absorbing member may be a rubber, copper or brass damping material attached to the outer surface of the mast.
According to this, when a pair of mast receives external force and a mast deform | transforms, a damping material deform | transforms according to a deformation | transformation of a mast. By converting the displacement energy generated in the mast into the displacement energy due to the deformation of the damping material and absorbing it, the stress generated in the mast can be reduced and the deformation amount of the mast can be reduced. In addition, it is possible to generate a damping force by the deformation of the damping material and to reduce the stress generated on the mast while converging the periodic vibration of the mast. Therefore, the stress which arises in a mast can be reduced by absorbing a part of displacement energy with a damping material. Moreover, by making the damping material of rubber, the manufacturing cost of the forklift can be suppressed, and by making it of copper or brass, the structure for reducing the stress generated in the mast can be simplified.

  According to the present invention, the stress generated on the mast can be reduced.

The side view showing the forklift of an embodiment. The top view which shows the front part of a forklift. The perspective view which shows a mast and a damper. Sectional drawing which shows a damper. The rear view which shows a mast and a damper. (A) is a figure which shows the state which the twist produced in the mast, (b) is a figure which shows the state which the tilt produced in the mast. The rear view which shows the energy absorption member of another example. The perspective view which shows the energy absorption member of another example.

  Hereinafter, one embodiment which materialized a forklift will be described according to FIGS. 1 to 6. First, in the following description, “front”, “rear”, “left”, “right”, “upper” and “lower” refer to “front” and “rear” when the forklift driver is facing the front of the forklift. "Left" "right" "upper" "lower" shall be shown.

  As shown in FIG. 1, the forklift 10 includes a pair of masts 13 erected at the front of the vehicle body 12. The forklift 10 includes a tilt cylinder 14 that tilts both masts 13 back and forth. Further, the forklift 10 includes a drive wheel 15 (front wheel) provided on the lower front side of the vehicle body 12 and a steered wheel 16 (rear wheel) provided on the lower rear side of the vehicle body 12. The forklift 10 is provided with a travel motor 17 for driving the drive wheels 15 on the vehicle body 12. Furthermore, the forklift 10 includes a battery 18 that supplies power to the traveling motor 17. The traveling motor 17 is driven by the power supplied from the battery 18. The forklift 10 travels by driving the driving wheels 15 by driving the traveling motor 17.

  As shown in FIG. 2, each mast 13 has an outer mast 19 and an inner mast 20 disposed inside each outer mast 19. The forklift 10 includes a lift bracket 23 supported by a pair of inner masts 20. Further, the forklift 10 includes a pair of left and right forks 11 supported by the lift bracket 23.

  As shown in FIG. 3 or FIG. 5, the forklift 10 includes a first outer mast support 21 connecting the pair of left and right outer masts 19. The first outer mast support 21 connects the upper ends of the pair of outer masts 19 with each other. In a plan view of the forklift 10 as viewed from above, the first outer mast support 21 is substantially U-shaped. Each longitudinal end of the first outer mast support 21 is fixed to the outer surface of each outer mast 19. The longitudinally extending portion of the first outer mast support 21 is located rearward of the rear surface of the outer mast 19.

  The forklift 10 includes a second outer mast support 31 connecting the pair of left and right outer masts 19. The second outer mast support 31 connects the pair of outer masts 19 below the first outer mast support 21. In a plan view of the forklift 10 as viewed from above, the second outer mast support 31 is substantially U-shaped. Each longitudinal end of the second outer mast support 31 is fixed to the outer surface of each outer mast 19. The longitudinally extending portion of the second outer mast support 31 is located rearward of the rear surface of the outer mast 19.

  As shown in FIG. 2, the forklift 10 includes an inner mast support 22 connecting the pair of left and right inner masts 20. In a plan view of the forklift 10 as viewed from above, the inner mast support 22 is rectangular. Further, the forklift 10 has a pair of lift cylinders 24 on the left and right. The piston rods 24 a of both lift cylinders 24 are connected to the longitudinal end of the inner mast support 22.

  Then, by the movement of both piston rods 24 a in the vertical direction (vertical direction), the pair of left and right inner masts 20 are moved up and down via the inner mast support 22. As a result, the lift bracket 23 moves up and down together with the pair of left and right inner masts 20. Therefore, the lift bracket 23 is supported by the pair of masts 13 so as to be movable up and down.

  Moreover, as shown in FIG. 3 or FIG. 5, the forklift 10 includes a tilt bracket 25 bridged between the left and right outer masts 19. The tilt bracket 25 is disposed below the second outer mast support 31. In a plan view of the forklift 10 from above, the tilt bracket 25 is substantially U-shaped. Each longitudinal end of the tilt bracket 25 is fixed to the outer surface of each outer mast 19. The longitudinally extending portion of the tilt bracket 25 is rearward of the rear surface of the outer mast 19.

  As shown in FIG. 1, the piston rod 14 a of the tilt cylinder 14 described above is connected to the outer surface of each longitudinal end of the tilt bracket 25. Then, the left and right masts 13 are tilted back and forth via the tilt bracket 25 by the movement of the two piston rods 14 a in the front and back direction.

  The forklift 10 includes a pair of dampers 40. The damper 40 functions as an energy absorbing member for absorbing displacement energy generated in the mast 13. The mast 13 has a tilt in the front-rear direction or in the left-right direction, a twist of each mast 13, and a pair of masts 13 relative to each other due to an impact generated when the forklift 10 running on the vehicle takes a step. Deformation such as misaligned twist occurs. During these deformations, the metal mast 13 is elastically deformed and displacement energy is generated in the mast 13.

  Also, the elastically deformed mast 13 tries to return to the original shape, but since inertia is working, the mast 13 deforms in the opposite direction past the original position. By repeating such behavior, periodic vibration occurs in the mast 13. The damper 40 absorbs the displacement energy generated in the mast 13 and converges the periodic vibration.

  As the damper 40, what is generally called an oil shock absorber (oil damper) is used. As an oil shock absorber, although there are a single cylinder type and a double cylinder type, a single cylinder type is adopted in this embodiment.

  As shown in FIG. 4, the damper 40 includes an outer cylinder 41. A first piston 42 is accommodated in the outer cylinder 41 so as to be capable of reciprocating in the axial direction of the outer cylinder 41. The inside of the outer cylinder 41 is divided by the first piston 42 into an oil chamber 41 a and a gas chamber 41 b. In the damper 40, the gas chamber 41b side along the axial direction of the outer cylinder 41 is one end side in the axial direction, and the oil chamber 41a side is the other end side in the axial direction. The oil chamber 41a is filled with oil, and the gas chamber 41b is filled with high-pressure gas.

  The second piston 44 is accommodated in the oil chamber 41 a so as to be capable of reciprocating in the axial direction of the outer cylinder 41. The second piston 44 is provided with a port 44a as a throttle. When the second piston 44 moves, oil passes through the port 44 a to generate resistance, which generates a damping force in the damper 40. The smaller the flow passage cross-sectional area of the port 44a, the greater the resistance and the higher the damping force, and the larger the flow passage cross-sectional area of the port 44a, the smaller the resistance and the lower the damping force.

  One end of a piston rod 43 is connected to the second piston 44, and the other end side of the piston rod 43 protrudes from the other end side in the axial direction of the outer cylinder 41. Further, the damper 40 is provided with a mounting portion 46 on one end side in the axial direction of the outer cylinder 41, and the piston rod 43 protrudes from the other end side in the axial direction of the outer cylinder 41.

  As shown in FIG. 3 or 5, one of the pair of dampers 40 is referred to as a first damper 40A, and the other damper is referred to as a second damper 40B. The mounting portion 46 of the first damper 40A is fixed to the right end as one end in the longitudinal direction of the tilt bracket 25, and the projecting end of the piston rod 43 is the left end as the other end in the longitudinal direction of the second outer mast support 31. It is fixed to

  Therefore, in the first damper 40A, the mounting portion 46 side of the outer cylinder 41 is disposed on the right side of the mast 13 side, and the projecting end side of the piston rod 43 is disposed on the left side of the mast 13 side. Therefore, the first damper 40A is connected to the second outer mast support 31 and the tilt bracket 25 so as to be bridged between the pair of masts 13. The first damper 40A is disposed such that the axial direction of the outer cylinder 41 obliquely intersects the axial direction of the mast 13.

  A bracket 32 is fixed to a left end as the other end in the longitudinal direction of the tilt bracket 25 and a right end as the one end in the longitudinal direction of the second outer mast support 31. The bracket 32 is substantially U-shaped. One end of the bracket 32 is fixed to the tilt bracket 25 or the second outer mast support 31. The other end of the bracket 32 is disposed rearward of the rear surface of the tilt bracket 25 or the second outer mast support 31. The other end of the bracket 32 is located rearward of the outer cylinder 41 of the first damper 40A.

  The mounting portion 46 of the second damper 40B is fixed to the bracket 32 fixed to the tilt bracket 25 among the pair of brackets 32, and the bracket 32 fixed to the second outer mast support 31 The projecting end of the piston rod 43 of the damper 40B is fixed.

  Therefore, in the second damper 40B, the mounting portion 46 side of the outer cylinder 41 is disposed on the left mast 13 side, and the projecting end side of the piston rod 43 is disposed on the right mast 13 side. Therefore, the second damper 40 B is connected to the second outer mast support 31 and the tilt bracket 25 so as to be bridged between the pair of masts 13. In addition, the second damper 40B is disposed at a position farther to the rear than the first damper 40A by the pair of brackets 32, and is disposed at a position not interfering with the first damper 40A. Further, the second damper 40 B is disposed in such a manner that the axial direction of the outer cylinder 41 obliquely intersects with the axial direction of the mast 13. The first damper 40A and the second damper 40B are installed in a state of being hooked on the pair of masts 13. Therefore, the pair of dampers 40 (the first damper 40A and the second damper 40B) are disposed apart from each other in the front-rear direction.

Next, the operation of the forklift 10 will be described.
Although not shown, it is assumed that the forklift 10 climbs over the step while the forklift 10 is traveling in a state where the lift bracket 23 is lifted together with the pair of left and right inner masts 20 and the material loaded on the fork 11 is lifted. . When crossing the step, the left and right drive wheels 15 cross the step with a time difference, and an impact as an external force is applied to the vehicle body 12 with a time difference.

  As shown in FIG. 6 (a), due to the displacement of the point of impact occurrence and the inertial force of the load, each of the pair of masts 13 (only the outer mast 19 is shown in FIG. 6 (a)) While a twist generate | occur | produces, the twist which the pair of masts 13 mutually shifted | deviated relative position arises.

  For example, when the left mast 13 is shifted backward and the right mast 13 is twisted forward, the left damper 13 is shifted backward to move the first damper 40A through the second outer mast support 31. The piston rod 43 of the first damper 40A is pressed, and the piston rod 43 of the first damper 40A is inserted into the outer cylinder 41. At the same time, the piston rod 43 of the second damper 40B is pulled through the second outer mast support 31 by the right mast 13 shifted forward, and the piston rod 43 of the second damper 40B protrudes from the outer cylinder 41.

  When twisting occurs, the displacement energy of each mast 13 is converted to the displacement energy of the piston rod 43 of the first and second dampers 40A and 40B, and the displacement energy generated in each mast 13 is absorbed. As a result, the amount of deformation of each mast 13 is reduced.

  Each of the masts 13 is deformed and then returned to its pre-deformed position, but is deformed in the opposite direction past the original position due to inertia. By this repetition, periodic vibration occurs in the mast 13. In the first and second dampers 40A and 40B, the piston rod 43 reciprocates following the periodic vibration of the mast 13. When the piston rod 43 reciprocates, oil passes through the port 44 a of the second piston 44. The resistance generated when oil passes through the port 44a converts kinetic energy of the piston rod 43 into heat energy, absorbs it, and generates a damping force. The periodic vibration of the mast 13 is converged by this damping force.

Therefore, while the twist of a pair of masts 13 is suppressed by the 1st damper 40A and the 2nd damper 40B, periodic vibration converges rapidly.
Further, as shown in FIG. 6B, when the pair of masts 13 (only the outer mast 19 is shown in FIG. 6B) is inclined to the left, when the inclination occurs, the left mast 13 The piston rod 43 of the first damper 40A is pulled through the second outer mast support 31, and the piston rod 43 of the first damper 40A protrudes from the outer cylinder 41. At the same time, the piston rod 43 of the second damper 40B is pressed by the right mast 13 via the second outer mast support 31, and the piston rod 43 of the second damper 40B is retracted into the outer cylinder 41.

  When inclination occurs, the displacement energy of each mast 13 is converted to the displacement energy of the piston rod 43 of the first and second dampers 40A and 40B, and the displacement energy generated in each mast 13 is absorbed. As a result, the amount of deformation of each mast 13 is reduced.

  In addition, each mast 13 returns to the position before deformation after being deformed, but since inertia is applied, it is deformed again in the opposite direction beyond the original position. By this repetition, periodic vibration occurs in the mast 13. In the first and second dampers 40A and 40B, the piston rod 43 reciprocates following the periodic vibration of the mast 13. When the piston rod 43 reciprocates, oil passes through the port 44 a of the second piston 44. The resistance generated when oil passes through the port 44a converts kinetic energy of the piston rod 43 into heat energy, which is absorbed and generates a damping force. The periodic vibration of the mast 13 is converged by this damping force.

  Although the pair of masts 13 may be inclined to the right, in this case, the first damper 40A and the second damper 40B move in the opposite direction to the case where the mast 13 is inclined to the left, and the inclination of the mast 13 The periodic vibration is converged while suppressing the Therefore, while the inclination of a pair of masts 13 is suppressed by the 1st damper 40A and the 2nd damper 40B, periodic vibration converges rapidly.

  Although not shown, when the pair of masts 13 is inclined forward or backward, the piston rods 43 of the first and second dampers 40A and 40B simultaneously project or retract from the outer cylinder 41 when the inclination occurs. . Then, the displacement energy of each mast 13 is converted into the displacement energy of the piston rod 43 of the first and second dampers 40A and 40B, and the displacement energy generated in each mast 13 is absorbed. As a result, the amount of deformation of each mast 13 is reduced.

  In addition, each mast 13 returns to the position before deformation after being deformed, but since inertia is applied, it is deformed again in the opposite direction beyond the original position. By this repetition, periodic vibration occurs in the mast 13. In the first and second dampers 40A and 40B, the piston rod 43 reciprocates following the periodic vibration of the mast 13. When the piston rod 43 reciprocates, oil passes through the port 44 a of the second piston 44. The kinetic energy of the piston rod 43 is converted into heat energy and absorbed by the resistance generated when oil passes through the port 44a, and a damping force is generated. The periodic vibration of the mast 13 is converged by this damping force. Therefore, while the inclination of a pair of masts 13 is suppressed by the 1st damper 40A and the 2nd damper 40B, periodic vibration converges rapidly.

According to the above embodiment, the following effects can be obtained.
(1) The displacement energy generated with the deformation of the mast 13 can be converted to the displacement energy of the damper 40 and absorbed. As a result, the amount of deformation of the mast 13 can be reduced. Furthermore, the periodic vibration of the mast 13 can be converged by the damper 40. Therefore, when displacement energy is generated in the mast 13 by an external force, stress generated in the mast 13 can be reduced by using the damper 40 as compared with the case where all of the displacement energy is used as displacement energy of the mast 13 Damage can be suppressed.

  (2) The forklift 10 includes the pair of dampers 40. Each damper 40 is connected to the second outer mast support 31 and the tilt bracket 25 so as to be bridged between the pair of masts 13. For this reason, while being able to make small deformation amount of each mast 13 by each damper 40, periodic vibration can be made to converge rapidly.

  (3) The pair of dampers 40 is installed in a state of being hooked on the pair of masts 13. Each damper 40 follows the deformation of each mast 13 so that the piston rod 43 appears and retracts. Therefore, by installing the pair of dampers 40 in a hooked state, it is also possible to reduce the twisting of the pair of masts 13 relative to each other.

  (4) The first damper 40A and the second damper 40B are spaced apart in the front-rear direction. For this reason, when a twist arises in a pair of masts 13, it can prevent that the 1st damper 40A and the 2nd damper 40B interfere.

The above embodiment may be modified as follows.
As shown in FIG. 7, the energy absorbing member includes the fluid pressure cylinder 50, the fluid pipe 51 connected to the fluid pressure cylinder 50, the variable throttle 52 connected to the fluid pipe 51, and the variable throttle 52 And a tank 54 connected to the fluid pipe 51.

  In the cylinder tube 50a of the fluid pressure cylinder 50, a piston 50b is accommodated so as to be capable of reciprocating in the axial direction of the cylinder tube 50a. One end of a piston rod 55 is connected to the piston 50b. The inside of the cylinder tube 50a is divided by a piston 50b into a first pressure application chamber 50c and a second pressure application chamber 50d. The first pressure working chamber 50c and the second pressure working chamber 50d are filled with oil as a fluid. One end of the fluid pipe 51 communicates with the first pressure working chamber 50c, and the other end communicates with the second pressure working chamber 50d. A variable throttle 52 is installed in the fluid pipe 51. The variable throttle 52 can adjust the flow passage cross-sectional area of the fluid pipe 51. A tank 54 is connected to the variable throttle 52.

  And one end side of the cylinder tube 50a which is one axial end of the fluid pressure cylinder 50 is disposed on one (right side in FIG. 7) mast 13 side, and the piston rod 55 side is on the other (left side in FIG. 7) mast 13 side As disposed, the hydraulic cylinder 50 is coupled to the tilt bracket 25 and the second outer mast support 31.

  In this configuration, when the mast 13 is deformed, the piston rod 55 protrudes and retracts with respect to the cylinder tube 50a. By converting the displacement energy generated with the deformation of the mast 13 into the displacement energy of the piston rod 55 in the fluid pressure cylinder 50 and absorbing it, the stress generated in the mast 13 can be reduced and the deformation amount of the mast 13 is reduced. it can.

  In addition, although the mast 13 is elastically deformed to generate periodic vibration, the piston rod 55 reciprocates in accordance with the periodic vibration of the mast 13. When the piston rod 55 reciprocates, fluid is supplied / discharged from the first pressure application chamber 50c or the second pressure application chamber 50d to the fluid pipe 51. At this time, the fluid passes through the variable throttle 52. The resistance generated when the fluid passes through the variable throttle 52 converts the displacement energy into heat energy, absorbs the displacement energy and generates a damping force. The periodic vibration of the mast 13 is converged by this damping force. Therefore, when displacement energy is generated in the mast 13 by an external force, stress generated in the mast 13 is obtained by using the energy absorbing member as compared with the case where all the displacement energy is kept as displacement energy of the mast 13. It can be reduced.

The variable stop 52 may be changed to an accumulator or may be changed to a fixed stop. Also, the fluid may be air.
As shown in FIG. 8, the energy absorbing member may be a damping material 60 attached to the outer mast 19 of the mast 13. The material of the damping member 60 may be any material that can absorb the displacement energy when the mast 13 is deformed, and examples thereof include rubber, copper, and brass. Damping material 60 is flat. The damping material 60 is preferably attached to substantially the entire left and right outer side surfaces and the front and rear outer side surfaces of the outer mast 19 in the mast 13, but even if it is attached to a part of the outer side surface of the outer mast 19 Good.

  In such a configuration, when the pair of masts 13 receives an external force and the masts 13 are deformed, the damping material 60 is deformed following the deformation of the masts 13. By converting the displacement energy generated in the mast 13 into the displacement energy due to the deformation of the damping material 60 and absorbing it, the stress generated in the mast 13 can be reduced and the deformation amount of the mast 13 can be reduced. In addition, the deformation of the damping member 60 generates a damping force, thereby reducing the stress generated in the mast 13 while converging the periodic vibration of the mast 13. Therefore, the stress generated in the mast 13 can be reduced by absorbing a part of the displacement energy by the damping material 60.

  When the damping material 60 is made of copper or brass, the structure for reducing the stress generated on the mast 13 can be simplified. Moreover, when the damping material 60 is made of rubber, the stress generated on the mast 13 can be reduced at low cost.

  In the embodiment, the mounting portion 46 of the damper 40 is connected to the tilt bracket 25 and the piston rod 43 is connected to the second outer mast support 31. However, the mounting portion 46 of the damper 40 and the piston rod 43 are external masts of the mast 13 It may be directly linked to 19.

The forklift 10 may include the damper 40 as an energy absorbing member and the damping material 60 attached to the outer surface of the outer mast 19.
The damper 40 may be a double cylinder type.

The throttling in the damper 40 may be a valve or an orifice instead of the port 44a.
The damper 40 may be installed in a state in which the axis of the outer cylinder 41 is parallel to the axis of the mast 13 without hooking.

The damper 40 may be only one, and may be installed in a state of being bridged over a pair of masts 13.
The forklift 10 may not be electrically driven by the traveling motor 17 but may be engine-driven by the engine.

  In the embodiment, the pair of masts 13 may be a multi-stage type provided with two or more inner masts 20 inside each outer mast 19.

  Reference Signs List 10 forklift, 12 vehicle body, 13 mast, 40 damper as an energy absorbing member 41 outer cylinder 43 piston rod 44 second piston 44 a port as a throttle 50 fluid pressure cylinder 50a: cylinder tube, 50b: piston, 50c: first pressure acting chamber, 50d: second pressure acting chamber, 51: fluid pipe, 52: variable throttle, 54: tank, 55: piston rod, 60: damping material.

Claims (7)

In a forklift comprising a pair of masts erected at the front of the vehicle body,
An energy absorbing member for absorbing displacement energy generated in the mast along with the deformation of the mast is provided on the mast.   The forklift according to claim 1, wherein the energy absorbing member is a damper installed in a state of bridging over the pair of the masts.   The damper includes a piston rod capable of moving in and out of an outer cylinder, and a piston connected to the piston rod in the outer cylinder, and the piston has a movement path of a fluid sealed in the outer cylinder. A throttle is provided, and the end of the outer cylinder which is one axial end of the damper is disposed on one of the masts, and the end of the piston rod projecting from the outer cylinder is disposed on the other mast The forklift according to claim 2.   The forklift according to claim 3, further comprising a pair of the dampers, wherein the pair of the dampers are installed in a state of being hooked on a pair of the masts.   5. The forklift according to claim 4, wherein the pair of dampers are disposed apart from each other in the front-rear direction.   The energy absorbing member is connected to each of a pair of pressure action chambers defined by a fluid pressure cylinder installed in a state of bridging over the pair of masts and a piston accommodated in a cylinder tube of the fluid pressure cylinder. A fluid pipe, a tank connected to the fluid pipe, and a throttle for adjusting a flow passage cross-sectional area of the fluid pipe, the fluid pressure cylinder including a piston rod capable of moving in and out of the cylinder tube The piston rod is connected to the piston, and an end of the fluid pressure cylinder at one end in the axial direction of the cylinder is disposed on one of the masts, and the piston rod is disposed on the other mast. The forklift according to claim 1.   The forklift according to claim 1, wherein the energy absorbing member is a rubber, copper or brass damping material attached to the outer surface of the mast.