JP6785145B2 - Loading platform lifting device - Google Patents

Description

The present invention relates to a cargo receiving platform elevating device mounted on a freight vehicle.

Conventionally, in a freight vehicle, a loading platform lifting device installed behind the loading platform is known. This load receiving platform elevating device is shown in, for example, Patent Document 1.

In the conventional loading platform elevating device, for example, when unloading, the loading platform is unfolded from the stored state and lowered from the loading platform so as to touch the ground. The "ground" is not limited to the ground surface such as a road surface on which a freight vehicle can travel, but also includes a surface having a height difference from the ground surface such as an upper surface of a concrete pedestal. In other words, the entire surface on the ground side that the consignment stand can touch during cargo handling is called the "ground". The angle (tilt) of the loading platform is adjusted by the positional relationship with the ground. The loading platform is raised and lowered by a hydraulically driven lift cylinder, and the loading platform is deployed and the angle is adjusted by a hydraulically driven tilt cylinder. The tilt cylinder contracts when the hydraulic oil is discharged when the load receiving table is deployed and when the angle of lowering the rear of the load receiving table is adjusted.

However, in this conventional load receiving platform elevating device, the operating speed is constant because the amount of hydraulic oil discharged in the contraction operation of the tilt cylinder is constant. Therefore, at the end of the contraction operation of the tilt cylinder, the balance of the load on the load cradle may be lost due to the impact when the load cradle touches the ground or the operation at a rapid speed, and the load may fall or fall. There was room for improvement.

Japanese Unexamined Patent Publication No. 58-12844 (Fig. 2)

Therefore, it is an object of the present invention to provide a load receiving platform elevating device capable of reducing the operating speed at the end of the contraction operation of the tilt cylinder.

The present invention is a load receiving platform lifting device mounted on a freight vehicle, which is a load receiving table on which luggage is placed, a hydraulically driven lift cylinder for raising and lowering the loading platform, and a hydraulic drive for adjusting the angle of the loading platform. A tilt cylinder and a power unit that supplies hydraulic oil to the lift cylinder and the tilt cylinder are provided, and the tilt cylinder is connected to a cylindrical cylinder tube, a piston that reciprocates in the cylinder tube, and the piston. A piston rod, a valve portion provided on the tip side of the piston so as to be movable in the axial direction of the piston rod, and an urging portion for urging the valve portion toward the tip of the tilt cylinder. The cylinder tube is provided with a downstream oil passage on the tip side of the movable range of the piston, and the valve portion has a cross-sectional area larger than the actual cross-sectional area of the oil-passing portion in the downstream oil passage. The load receiving platform elevating device is configured to cover the downstream oil passage in a state where the passage of hydraulic oil is allowed with a reduced amount of oil before the piston reaches the tip of the movable range.

According to the above configuration, the valve portion can cover the downstream oil passage with a reduced amount of oil allowing the passage of hydraulic oil before the piston reaches the tip of the movable range. Therefore, the piston can be decelerated by reducing the amount of oil passing on the downstream side of the tilt cylinder. Therefore, the speed of the angle change of the load receiving table can be reduced via the piston rod.

Furthermore, the piston rod includes a spindle that projects in the axial direction of the piston rod from the surface on the tip side, and the downstream oil passage is the piston rod in a state where the piston reaches the tip of the movable range. The spindle has a portion extending in the axial direction of the piston rod from the surface on the tip side of the piston rod, and the spindle enters the downstream oil passage in a state where the piston reaches the tip of the movable range, and the valve portion is the valve portion. A through hole through which the spindle penetrates and has a cross-sectional area larger than the cross-sectional area of the spindle can be provided.

According to this configuration, the hydraulic oil passes through the gap between the through hole of the valve portion and the spindle. Therefore, when the valve portion closes the downstream oil passage, it is not necessary to separately form an oil passage for passing the hydraulic oil having a reduced amount of oil.

Further, the cylinder tube or the piston may be provided with a recess into which the valve portion enters in a state where the piston reaches the tip of the movable range.

According to this configuration, when the piston rod contracts and the piston reaches the tip of the movable range, the valve portion enters the recess, so that the valve portion can be prevented from being sandwiched between the piston and the cylinder tube and broken.

Further, the urging portion is a coil spring, the piston rod has a protruding portion protruding from the piston toward the tip end side, and the coil spring is fitted in the protruding portion, and the base end side of the valve portion. Is formed with a spring support recess in which the tip of the coil spring is located.

According to this configuration, the coil spring as the urging portion is guided by the piston rod, and the position of the valve portion and the coil spring can be prevented from being displaced by the spring support recess, so that the valve portion is not displaced. It can be operated.

According to the present invention, the rate of change in the angle of the loading platform can be reduced via the piston rod. Therefore, the operating speed can be reduced at the end of the contraction operation of the tilt cylinder, and the imbalance of the load on the loading platform can be suppressed.

FIG. 1 is a side view schematic view in which a cargo cradle lifting device according to an embodiment of the present invention is mounted on a freight vehicle and each state of the cradle is collectively shown. FIG. 2 is a side view showing a load receiving platform elevating device in a stored state. FIG. 3 is a partial vertical sectional view showing a tilt cylinder. FIG. 4 is an enlarged view of a main part of FIG. 5 (a) to 5 (f) are side views showing the posture change of the load receiving table due to the tilt cylinder in order. 6 (a) to 6 (f) are side views showing the posture change of the load receiving table due to the tilt cylinder in order. FIG. 7 is an enlarged view of a main part of FIG. 6A. FIG. 8 is an enlarged view of a main part of FIG. 6 (b). FIG. 9 is an enlarged view of a main part of FIG. 6 (d). FIG. 10 is a plan view showing the arrangement of the power unit and the like in the load receiving platform elevating device. 11A and 11B show the positional relationship between the power unit and the front cover, FIG. 11A is a plan view, and FIG. 11B is a view seen from the rear side of the vehicle. FIG. 12 is a hydraulic circuit diagram of the power unit. FIG. 13 is a hydraulic circuit diagram of the power unit according to another embodiment.

Next, an embodiment of the present invention will be taken up and described. The vertical direction in the following description is the vertical direction on the paper surface of FIG. In addition, the front-back and left-right directions correspond to the front-back and left-right directions of the freight vehicle. That is, the left side in FIG. 1 is "front", the right side is "rear", and the direction orthogonal to the paper surface in FIG. 1 is the left-right direction. The lift cylinder 2 is the contraction side of the piston rod, the side of the load receiving base 1 in the present embodiment is the "base end side", and the extension side of the piston rod is the lift frame 5 in the present embodiment. The side is referred to as the "tip side". Regarding the tilt cylinder 3, the extension side of the piston rod 33, the side of the load receiving base 1 in the present embodiment is the “base end side”, and the contraction side of the piston rod 33 is the lift frame 5 in the present embodiment. The side is referred to as the "tip side".

As shown in FIG. 1 (shown in the mounted state on the freight vehicle T) and FIG. 2 (shown with the consignment 1 and the cylinders 2 and 3 extracted), the load receiving platform lifting device Pg of the present embodiment is shown in the cargo vehicle T. A hydraulically driven lift cylinder that is mounted on the rear part and is a type of hydraulic actuator that operates the loading platform 1 (also called "platform") on which luggage is placed and the loading platform 1 and raises and lowers the loading platform 1. 2, a type of the hydraulic actuator, a hydraulically driven tilt cylinder 3 for adjusting the angle of the load receiving base 1, and a power unit 4 (shown in FIG. 10) for supplying hydraulic oil to the lift cylinder 2 and the tilt cylinder 3. , Equipped with. Each of the cylinders 2 and 3 has a substantially cylindrical shape, and as shown in FIG. 10, a pair of cylinders 2 and 3 are provided on the left and right sides of the loading platform 1. Each of the cylinders 2 and 3 is configured to be able to expand and contract by allowing the piston rod to move in the axial direction with respect to the cylinder tube so that it can appear and disappear. The loading platform 1 is supported by a lift arm 6 that is rotatable with respect to a lift frame 5 fixed to the chassis of the freight vehicle T, and is operated by expanding and contracting each cylinder 2 and 3. Can be done. Further, the load receiving table 1 is supported by the lift arm 6 via a rotating shaft 7, and the tilt cylinder 3 can be rotated with respect to the freight vehicle T and the ground G such as the ground by expanding and contracting. Tilt operation).

As shown in FIG. 1 for each state of the cargo receiving table 1, for example, when unloading when the ground G is a horizontal plane, the cargo receiving table 1 stands upright with respect to the cargo bed of the freight vehicle T (state P1 / 2). It is rotated clockwise from the dotted line (shown by the dotted line) and expanded 90 ° backward, so that the upper surface 11 of the cargo bed is in a horizontal state (state P2). At the time of the change from the state P1 to the state P2, the tilt cylinder 3 contracts. In this state, the worker moves the load (not shown) from the loading platform to the loading platform 1. Then, the load receiving table 1 descends while the load receiving table upper surface 11 is horizontal (state P3). This descent is stopped in a state where a part of the loading platform 1 is in contact with the ground G (state P4). When the load receiving table 1 is lowered, the lift cylinder 2 contracts. When the ground G is a horizontal plane, the rear portion of the loading platform 1 is not yet in contact with the ground in this state P4. Then, the angle of the cradle 1 is adjusted according to the height and inclination of the ground G, and the rear portion of the cradle 1 touches the ground (state P5 / shown by the alternate long and short dash line). At the time of the change from the state P4 to the state P5, the tilt cylinder 3 contracts. In this state P5, the worker unloads the load on the ground G. At the time of loading, the opposite of the above, that is, in the state P5, the worker moves the load from the ground G onto the cradle 1 and changes the angle of the cradle 1 to the state P4, and the state P4 is changed to the cradle. 1 changes to the rising state P2. When the loading on the loading platform is completed, the state P1 is set and the freight vehicle T can run. In the cargo receiving platform elevating device Pg of the present embodiment, this operation is performed by an operator such as a driver of the freight vehicle T operating a switch of a controller (not shown).

When the load receiving table 1 is raised and the load receiving table 1 is rotated counterclockwise in FIG. 1, each of the cylinders 2 and 3 is extended by supplying hydraulic oil under pressure from the power unit 4. On the contrary, when the load receiving table 1 is lowered and the load receiving table 1 is rotated clockwise in FIG. 1, the cap side provided on the cylinder cap (the portion of the tilt cylinder 3 indicated by reference numeral 31A (see FIG. 3)) is provided. Since the port (corresponding to the downstream oil passage outlet 3113 in the tilt cylinder 3) communicates with the tank 45 (see FIGS. 10 to 12), the cylinders 2 and 3 are mainly due to the gravity applied to the cradle 1. The piston rod is moved in the contraction direction, hydraulic oil is discharged from each of the cylinders 2 and 3, and the hydraulic oil flows out to the power unit 4 to contract. At the moment when the load receiving table 1 starts to fall from the state P1 shown in FIG. 1, gravity does not easily work in the direction of tilting the load receiving table 1, so the spring 37 provided inside the tilt cylinder 3 causes the load receiving table 1 to fall. On the other hand, it causes the force to fall backward.

A stopper 12 projects upward from the rear portion of the upper surface 11 of the loading platform 11 to prevent the load from sliding backward from the loading platform 1. The stopper 12 is movable and can be stored in the loading platform 1.

Of the cylinders 2 and 3, the tilt cylinder 3 has a built-in reduction mechanism 3s. Here, from immediately before the state P4 shown in FIG. 1 to the state P5, the conventional load receiving platform elevating device operates at a constant speed, so that the balance of the load on the load receiving table 1 is lost and the load is loaded. There was a possibility of falling or falling. In the present embodiment, the deceleration mechanism 3s suppresses the above possibility. The reduction mechanism 3s will be described below. The reduction mechanism 3s is provided in the tilt cylinder 3, but is not provided in the lift cylinder 2.

As shown in FIG. 3, the tilt cylinder 3 includes a tubular cylinder tube 31, a piston 32 that reciprocates in the cylinder tube 31, and a piston rod 33 that is connected to the piston 32. Note that FIG. 3 shows a state in which the tilt cylinder 3 is in the most contracted state and the deceleration mechanism 3s is working.

The cylinder tube 31 is provided with a cylinder cap 31A on the tip end side. A downstream oil passage 311 is provided on the tip side of the movable range of the piston 32. The cylinder tube 31 is provided with a recess 312 having a space for the valve portion 35 to enter in a state where the piston 32 reaches the tip of the movable range. The downstream oil passage 311 is a shaft extending in the axial direction of the piston rod (the axial direction of the piston rod 33, the same applies hereinafter) from the surface on the tip side of the piston rod 33 in a state where the piston 32 reaches the tip of the movable range. It has a directional oil passage 3111 and a radial oil passage 3112 extending radially from the tip end side of the axial oil passage 3111 and opening to the outer peripheral surface of the cylinder tube 31. The axial oil passage 3111 has a space in which the spindle 34, which will be described later, can enter.

The recess 312 of the present embodiment is formed by expanding the inner diameter of the proximal end side portion of the axial oil passage 3111. The cross-sectional shape of the downstream oil passage 311 (including the recess 312) is circular. As shown in FIGS. 3 and 4, the valve portion 35 and the protruding portion 331 of the piston rod 33, which will be described later, can be inserted into the recess 312. The valve portion 35 comes into contact with the tip-side inner surface 3121 of the recess 312. This contact prevents the hydraulic oil from passing between the tip surface of the valve portion 35 and the tip-side inner surface 3121 in the recess 312. When the valve portion 35 enters the recess 312, it is possible to prevent the valve portion 35 from being sandwiched between the piston 32 and the cylinder tube 31 and being broken. Further, the movable range of the piston 32 is such that after the valve portion abuts on the cylinder cap 31A of the cylinder tube 31, and before the piston 32 abuts on the cylinder cap 31A (before the piston 32 reaches the tip of the movable range). Since the piston 32 does not come into contact with the 35 and is not reduced due to the presence of the valve portion 35, the movable range of the piston 32 can be set to the maximum. Therefore, since a large angle can be obtained when the load receiving table 1 is tilted rearward, the rear portion of the load receiving table 1 can be grounded even if there is a distance between the ground G and the rear portion of the load receiving table 1. A packing may be provided on the tip surface of the valve portion 35 in order to more reliably prevent the passage of the hydraulic oil.

The piston rod 33 includes a spindle 34 that projects in the axial direction of the piston rod 33 from the surface on the tip end side. The spindle 34 of the present embodiment is a round bar-like body having a diameter smaller than that of the tip of the piston rod 33, and the base end 341 is located at the tip of the piston rod 33 so as to penetrate the piston 32. It is fixed by being screwed into. An enlarged portion 342 having an enlarged diameter is formed at the tip of the spindle 34 to prevent the valve portion from coming off. The cross-sectional shape of the spindle 34 of the present embodiment is circular. As shown in FIGS. 3 and 4, the spindle 34 enters the axial oil passage 3111 in the downstream oil passage 311 of the cylinder cap 31A in a state where the piston 32 reaches the tip of the movable range.

The tilt cylinder 3 further includes a valve portion 35 provided on the tip side of the piston 32 so as to be movable in the axial direction of the piston rod 33, and an urging portion 36 that urges the valve portion 35 toward the tip end of the tilt cylinder 3. And. As shown in FIGS. 3 and 4, the valve portion 35 in the present embodiment is provided on the tip side of the piston 32 on the tip side.

The valve portion 35 has a cross-sectional area larger than the actual cross-sectional area of the oil-passing portion in the axial oil passage 3111 in the downstream oil passage 311 in the cylinder tube 31. In the present embodiment, the "actual cross-sectional area of the oil passing portion" is the cross-sectional area of the spindle 34 (oil passing) in the state where the spindle 34 is inserted into the axial oil passage 3111 as shown in FIGS. 3 and 4. It is the cross-sectional area at the inlet end of the axial oil passage 3111, excluding the cross-sectional area of the portion that does not. The cross-sectional area of the spindle 34 may not be constant in the axial direction, for example, as the enlarged portion 342 exists in the present embodiment, but the "actual cross-sectional area of the oil passing portion" is the axial oil passage 3111. It will be evaluated at the entrance end. On the other hand, in a state where the spindle 34 does not enter the axial oil passage 3111, the "actual cross-sectional area of the oil passing portion" is the same cross-sectional area at the inlet end of the axial oil passage 3111. The valve portion 35 of this embodiment is a disk-shaped body. In the valve portion 35, the piston 32 reaches the tip of the movable range before the piston 32 reaches the tip of the movable range, specifically, after the valve portion 35 comes into contact with the tip side inner surface 3121 in the recess 312. It is configured to cover the downstream oil passage 311 (axial oil passage 3111) in a state where the passage of hydraulic oil is allowed with a reduced amount of oil. For this purpose, the valve portion 35 is provided with a through hole 351 having a cross-sectional area (diameter dimension) larger than the cross-sectional area (diameter dimension) of the spindle 34 at the center in the radial direction through which the spindle 34 penetrates. That is, the diameter dimension of the outer edge of the cross-sectional shape of the valve portion 35 is larger than the diameter dimension of the outer edge of the cross-sectional shape of the axial oil passage 3111. The diameter of the outer edge of the cross-sectional shape of the axial oil passage 3111 is larger than the diameter of the outer edge of the cross-sectional shape of the spindle 34 (the portion of the enlarged portion 342 in this embodiment). The cross-sectional shape of the through hole 351 of the present embodiment is circular, and has a diameter dimension larger than the diameter dimension of the spindle 34. Therefore, there is a gap between the inner surface of the through hole 351 and the outer surface of the spindle 34. Even when the valve portion 35 is in contact with the tip-side inner surface 3121 of the recess 312 (that is, most of the axial oil passage 3111 is closed), a small amount of hydraulic oil can pass through this gap. it can. That is, even in the contacted state, the inlet of the axial oil passage 3111 is maintained in a reduced state. Here, the "small amount" means a small amount of oil as compared with the amount of passing oil when the axial oil passage 3111 is open.

The through hole 351 of the present embodiment has both an action of guiding the axial movement of the valve portion 35 by the spindle 34 and an action of keeping the inlet of the axial oil passage 3111 in a reduced state. Therefore, the deceleration mechanism 3s can be economically configured. Further, by forming the through hole 351 in the radial center of the valve portion 35, the valve portion 35 can have a rotationally symmetric shape, so that the valve portion 35 can be easily manufactured.

In the present embodiment, the urging portion 36 uses a coil spring that expands and contracts along the axial direction of the piston rod 33. By using the coil spring, it is possible to freely set the axial dimension in the free state (the state in which the valve portion 35 is not in contact with the tip side inner surface 3121 in the recess 312). Therefore, by appropriately selecting the length of the spindle 34 and the free-state dimension of the urging portion (coil spring) 36, the axial movement range of the valve portion 35, that is, the range in which the reduction mechanism 3s works can be freely selected. Can be set.

Here, the piston rod 33 includes a protruding portion 331 protruding from the piston 32 toward the tip end side. The protruding portion 331 of the present embodiment has a columnar shape, and an urging portion (coil spring) 36 is fitted in the protruding portion 331. As shown in FIGS. 3 and 4, the protruding portion 331 is inserted into the recess 312 when the piston 32 reaches the tip of the movable range. Further, a spring support recess 352 in which the tip end portion of the urging portion (coil spring) 36 is located is formed on the base end side of the valve portion 35. With this configuration, the urging portion (coil spring) 36 is axially guided by the protruding portion 331 of the piston rod 33, and the valve portion 35 and the urging portion (coil spring) are guided by the spring support recess 352. Since the position in the radial direction with the 36 can be prevented from shifting, the valve portion 35 can be reliably operated without shifting. In particular, by using a coil spring as the urging portion 36 as in the present embodiment, since the coil spring has a columnar space inside, the protruding portion 331 of the piston rod 33 is urged. Easy to insert into the coil spring) 36. The configuration is not limited to this, and for example, a guide member separate from the piston rod 33 may be provided, or a guide member may not be provided inside the coil spring which is the urging portion 36, and the piston rod may expand and contract without a guide. It may be configured to do so.

In the present embodiment, the central axes of the axial oil passage 3111, the spindle 34, and the valve portion 35 of the downstream oil passage 311 are aligned and are on the central axis of the piston rod 33. Therefore, even if the piston 32 and the piston rod 33 are displaced in the rotational direction when the piston 32 contracts, the spindle 34 enters the axial oil passage 3111 and the valve portion 35 covers the inlet of the axial oil passage 3111. Is made stable.

As described above, the speed reduction mechanism 3s included in the tilt cylinder 3 is composed of a downstream oil passage 311 (axial oil passage 3111), a recess 312, a protruding portion 331 of the piston rod 33, a spindle 34, a valve portion 35, and an urging portion 36. ing. Next, the operation accompanying the contraction of the tilt cylinder 3 of the reduction mechanism 3s will be described.

5 (a) to 5 (f) and 6 (a) to 6 (f) show the process of deploying the consignment cradle 1. Note that the angle of the load receiving table 1 is different between FIGS. 5 and 6 due to the difference in the degree of expansion and contraction of the lift cylinder 2. FIG. 5 shows a case where the surface where the wheels of the freight vehicle T are in contact with the ground and the ground G which is the surface where the cargo receiving platform 1 is lowered are at the same height. FIG. 6 shows a case where the wheels of the freight vehicle T are in contact with the ground. It shows a case where the ground G, which is the surface on which the cargo receiving platform 1 is lowered, is at a higher position than the surface on which the cargo cradle 1 is lowered. Incidentally, FIG. 6A shows a state of being stored in the freight vehicle T, which is a state in which the freight vehicle T can travel.

5 (a) and 6 (a) show the initial state of the extension side stroke end (extended most) of the tilt cylinder 3. 5 (b) (c) and 6 (b) (c) show the process of unfolding. In the states of FIGS. 5 (a) to 5 (c) and FIGS. 6 (a) to 6 (c), the hydraulic oil is discharged from the tilt cylinder 3 mainly due to the gravity applied to the cradle 1, and the hydraulic oil flows out to the power unit 4. As a result, the tilt cylinder 3 contracts, but up to this point, as shown in FIGS. 7 (enlarged view of FIG. 6A) and FIG. 8 (enlarged view of FIG. 6B), the valve portion 35 and the recess 312 Is not decelerated because they are far apart. 5 (d) and 6 (d) show the moment when deceleration is started. In the present embodiment, when the angle of the upper surface 11 of the loading platform 11 with respect to the horizontal plane rises backward to 3 ° (3 ° before the loading platform 1 becomes horizontal), FIG. 9 (enlarged view of FIG. 6D) As shown, the valve portion 35 comes into contact with the tip-side inner surface 3121 in the recess 312. Along with this contact, the hydraulic oil that is about to flow out of the tilt cylinder 3 due to gravity passes only through the gap between the inner surface of the through hole 351 in the valve portion 35 and the outer surface of the spindle 34. Therefore, the amount of oil spilled from the tilt cylinder 3 is reduced, so that the contraction speed of the tilt cylinder 3 is reduced. 5 (e) and 6 (e) show a state in which the upper surface 11 of the loading platform is horizontal. Then, when the rear portion of the load receiving table 1 touches the ground G while the upper surface 11 of the load receiving table is tilted backward to reach FIGS. 5 (f) and 6 (f), the deployment operation is stopped at that point. (In this embodiment, it is stopped by the switch operation of the operator). In this state, the tilt cylinder 3 further contracts, and the urging portion 36 shortens while the valve portion 35 is in contact with the tip-side inner surface 3121 in the recess 312. Therefore, deceleration is continued. Note that FIGS. 5 (f) and 6 (f) show the final state of the tilt cylinder 3 at the contraction side stroke end (most contracted). The speed reduction mechanism 3s is in the state shown in FIG. In this state, the upper surface 11 of the loading platform is tilted backward. For example, when the freight vehicle T is stopped in the middle of a downhill and cargo handling work is performed on the upside of the slope, the upper surface 11 of the loading platform 11 can be leveled in this state. In this state, the urging portion 36 is in the shortest state while the valve portion 35 is in contact with the tip side inner surface 3121 of the recess 312.

Through the above process, the valve portion 35 can cover the downstream oil passage 311 with a reduced amount of oil allowing the passage of hydraulic oil before the piston 32 reaches the tip of the movable range. Since the spindle 34 has entered the axial oil passage 3111 of the downstream oil passage 311 with the piston 32 reaching the tip of the movable range, the valve portion 35 is always hydraulic oil at the contraction side stroke end of the tilt cylinder 3. The passage of is reduced. The timing at which the passage of hydraulic oil starts to decrease (that is, when the valve portion 35 covers the downstream oil passage 311) depends on the timing at which the spindle 34 begins to enter the axial oil passage 3111 of the downstream oil passage 311. Can be adjusted.

In this way, the piston 32 can be decelerated by reducing the amount of oil passing on the downstream side of the tilt cylinder 3. Therefore, the speed of the angle change of the load receiving table 1 can be reduced via the piston rod 33. As a result, at the end of the contraction operation of the tilt cylinder 3, the impact when the load receiving table 1 touches the ground G and the rapid speed at the start of the operation when the load receiving table upper surface 11 is tilted rearward from the horizontal state to unload the load. It is possible to prevent the cargo from operating on the cradle 1 and prevent the load from falling due to the imbalance of the load on the loading platform 1, so that the cargo handling work can be performed safely. The tilt cylinder 3 may be stopped until it reaches the stroke end. In this case, if the spindle 34 has entered the axial oil passage 3111 of the downstream oil passage 311 at the time of stopping, the piston 32 can be decelerated as described above.

The same effect can be obtained by electrically controlling the amount of oil to be throttled at the end of the contraction operation of the tilt cylinder 3, but in the present embodiment, since the tilt cylinder 3 is provided with the reduction mechanism 3s, it is controlled. There is no particular need for a response in terms of aspects. Therefore, for example, there is an advantage that the control program of the load receiving platform elevating device Pg can be simplified. Further, since a sensor for detecting the horizontal state of the load receiving table upper surface 11 on the load receiving table 1 is not required, the configuration of the load receiving table lifting device Pg can be simplified and can be made inexpensive.

Then, in the configuration of the present embodiment, the hydraulic oil passes through the gap between the through hole 351 of the valve portion 35 and the spindle 34. Therefore, when the valve portion 35 closes the downstream oil passage 311, it is not necessary to separately form an oil passage for passing the hydraulic oil having a reduced amount of oil. Therefore, the structure of the tilt cylinder 3 provided with the reduction mechanism 3s can be simplified.

Next, the power unit 4 will be described. As shown in FIGS. 10 to 12, the power unit 4 of the present embodiment mainly consists of a main block 41 and a sub-block 42 which can be configured by combining a valve block containing a valve for controlling oil flow and the like, and an operation. An oil pump 43 that pumps oil to the outside of the power unit 4 (main block 41 and subblock 42 in this embodiment), a motor 44 that is a driving means for driving the oil pump 43, a tank 45 that can store hydraulic oil, and oil. A filter 46 is provided. The driving means is an electric motor 44 in the present embodiment, but is not limited to this, and may be, for example, a means that takes in a driving force from the outside of the power unit 4 to shift gears or the like.

The power unit 4 is fixed on a bracket 51 extending rearward of the lift frame 5. In the present embodiment, the power unit 4 is arranged behind the axis line Rc (see FIG. 1) of the rear wheels of the freight vehicle T.

The arrangement of the portions appearing in the appearance of the power unit 4 is as shown in FIGS. 10 and 11 (a) and 11 (b). The main block 41 is arranged vertically on the bracket 51, the sub block 42 is arranged on the bracket 51, and the sub block 42 is arranged on the left side of the main block 41 in the direction when viewed from the rear (the direction orthogonal to the paper surface in FIG. 11B). The motor 44 is arranged on the right side, and the tank 45 is arranged on the right side. Further, in the internal space of the tank 45, the oil supply pump 43 is arranged on the right side of the main block 41, and the oil filter 46 is arranged on the right side. The arrangement of the elements constituting the power unit 4 is not limited to that of the present embodiment, and can be arranged in various patterns.

In this embodiment, as shown in FIG. 11B, the upper end position of the motor 44 is lower than the upper end position of the tank 45 . The sub-block 42 is located above the motor 44 so that the upper end of the sub-block 42 does not protrude from the upper end position of the tank 45. By arranging the sub-block 42 in this way, the vertical dimensions of the power unit 4 can be made compact, and the cover 8 can also be made smaller.

In the main block 41, the solenoid portion 41s is positioned so as to project forward. Further, in the sub-block 42, the solenoid portions 42s and 42s are positioned so as to project to the left side.

Further, as shown in FIGS. 10 and 11 (a) and 11 (b), the front, rear, left, right, and upper sides of the power unit 4 are covered with a hollow substantially rectangular parallelepiped cover 8 (see FIGS. 11 (a) and 11 (b)). Shows only the front cover 81). The cover 8 is formed of a plate-like body and is assembled by bolts. Therefore, the power unit 4 can be exposed by removing it during maintenance of the power unit 4. Further, although not shown, the cover 8 may be provided with an opening for ventilation for cooling the motor 44 and the like.

The main block 41 includes a check valve 411 for preventing backflow in the direction toward the port 4143, a relief valve 412 which is opened when a predetermined pressure is exceeded, and a valve for suppressing an overpressure state in the entire hydraulic circuit. A solenoid valve 413 that is opened when the cylinders connected to the block (lift cylinder 2 and tilt cylinder 3 in this embodiment) contract, and a main block side oil passage 414 connected to each of the valves 411 to 413 are built-in. Has been done. As the solenoid valve 413 of the present embodiment, a 2-port 2-position switching type solenoid valve is used (however, the configuration of the solenoid valve is not limited to this). The main block side oil passage 414 has a port 4141 connected to the oil supply pump 43, a port 4142 connected to the tank 45, and a port 4143, 4144 connected to the sub block side oil passage 421 of the sub block 42. Be prepared. Each port 4141-4144 is formed in a shape capable of connecting a pipe joint, if necessary.

The main block 41 is in the middle of the oil passage from the main block side oil passage 414 to the tank 45 via the solenoid valve 413 (the hydraulic oil returning from the cylinders 2 and 3 to the tank 45 flows through this oil passage). In the embodiment, a flow control valve 415 for adjusting the amount of oil is provided on the downstream side (left side in FIG. 12) of the solenoid valve 413 when oil is flowing. Since the flow control valve 415 can make the amount of oil in the lift cylinder 2 at the time of contraction constant, the load receiving table 1 can be lowered at a constant speed even if the weights of the loads placed on the load receiving table 1 are different. The same applies to the tilt cylinder 3 in the present embodiment, and since the amount of oil at the time of contraction can be made constant by the flow control valve 415, the load receiving table 1 can be rotated at a constant speed. A filter 416 is provided between the solenoid valve 413 and the flow control valve 415. The flow control valve 415 and the filter 416 are not essential and may not be provided.

The main block side oil passage 414 is a first upper and lower oil passage 4145 connecting ports 4141 and 4143 and extending vertically, a second upper and lower oil passage 4146 connecting ports 4142 and 4144 and extending vertically, a first upper and lower oil passage and a second. The first upper and lower oil passages are connected to the upper and lower oil passages and extend to the left and right in the figure, below the first left and right oil passages 4147 and the first left and right oil passages where the solenoid valve 413, the flow control valve 415, and the filter 416 are located. It is composed of a second left and right oil passage 4148, which connects the second upper and lower oil passages and extends to the left and right in the drawing, and where the relief valve 412 is located. The check valve 411 is located between the branch portion of the first left and right oil passages and the branch portion of the second left and right oil passages in the first upper and lower oil passages 4145.

The sub-block 42 is connected above the main block 41. The sub-block 42 contains at least a sub-block side oil passage 421 connected to the main block-side oil passage 414 of the main block 41. The sub-block side oil passage 421 includes ports 4211 and 4212 connected to the main block 41 and ports 4213 and 4214 connected to each of the lift cylinder 2 and the tilt cylinder 3. Each of the ports 4211 to 4244 is formed in a shape capable of connecting a pipe joint, if necessary.

The sub-block 42 of the present embodiment further includes solenoid valves 422 and 423 for passing oil through one or both of the lift cylinder 2 and the tilt cylinder 3. Filters 424 and 425 are provided below the solenoid valves 422 and 423 (on the side of the oil supply pump 43 during oil flow).

The sub-block side oil passage 421 branches from the collecting oil passage 4215 located directly above the port 4211 and the collecting oil passage 4215 for passing oil to the lift cylinder 2 and extends to the port 4213, and extends to the solenoid valve 422 and the filter 424. Is located in the lift oil passage 4216 and the tilt cylinder 3, the tilt oil passage 4217 and the tilt oil are branched from the collecting oil passage 4215 and extend to the port 4214, and the solenoid valve 423 and the filter 425 are located. It consists of a self-sufficient oil passage 4218 that branches off from road 4217 and extends to port 4212 below. The self-sufficient oil passage 4218 is provided with a check valve 426 for preventing backflow in the direction toward the port 4212.

Depending on the model of the cargo receiving platform lifting device Pg, the tilting operation, which is an operation of rotating the cargo receiving platform 1 with respect to the freight vehicle T and the ground G such as the ground, is not performed by using the tilt cylinder 3. In this case (when the load receiving table 1 is manually rotated), it is not necessary to provide the tilt oil passage 4217, the self-sufficient oil passage 4218, the solenoid valve 423, and the filter 425 in the sub block 42.

Further, in the configuration provided with the tilt cylinder 3, the self-sufficient oil passage 4218 is an oil for sending hydraulic oil to the tilt cylinder 3 when the load receiving table 1 is manually rotated in order to store the load receiving table 1 from the deployed state. It's a road. Due to this self-sufficient oil passage 4218, the side of the tilt cylinder 3 where the piston rod 33 does not exist (the side of the cylinder cap 31A) becomes a vacuum state, and the next time the load receiving table 1 is deployed (the tilt cylinder 3 contracts). When), the piston rod 33 suddenly moves in the contraction direction, so that the load receiving table 1 can be prevented from suddenly rotating in the deployment direction. If such a manual operation is not performed, the self-sufficient oil passage 4218 can be omitted. In this case, the section between the port 4144 in the main block 41 and the branch portion of the first left and right oil passages 4147 in the second upper and lower oil passages 4146 is also functionally unnecessary. However, from the viewpoint of sharing the main block 41, in the present embodiment, the unnecessary portion is left provided in the main block 41 in a state where the port 4144 is closed so that the hydraulic oil does not leak. As a result, the main block 41 can be shared.

With the above configuration, a valve block suitable for a load receiving platform elevating device of a type in which the load receiving table 1 is opened and closed by the tilt cylinder 3 and the angle is changed (tilted) can be configured.

In the main block 41 and the sub block 42, the appearance of the main bodies 41 m and 42 m is formed in a substantially rectangular parallelepiped shape. However, the solenoid portions 41s and 42s in the valve block of the present embodiment protrude from the main body portions 41m and 42m, respectively. The main block 41 and the sub block 42 are used by being connected with their outer surfaces in contact with each other. At the time of this connection, ports 4143, 4211/4144, and 4212 located at the connection between the two are also connected. In the present embodiment, the connection is made by bolts, but the connection means is not particularly limited.

In this way, the main block 41 and the sub block 42 are configured to be connectable and detachable. Therefore, the sub-block 42 to be combined with the main block 41 can be changed to a sub-block 42 having a different structure. As a result, the function of the valve block can be easily changed. Therefore, the main block 41 is integrated with the essential parts of at least two different power unit 4 models of the hydraulic mechanism, and the sub-block 42 is added with the hydraulic mechanism. By consolidating various parts, that is, by sharing the functions between the main block 41 and the sub-block 42, it is possible to diversify the configuration of the valve block while standardizing the main block 41. That is, when manufacturing a valve block, for example, if the main block 41 for another model has excess inventory, the man-hours can be reduced as compared with manufacturing the entire valve block from the beginning by diverting the main block 41. .. Therefore, the degree of freedom regarding the function of the valve block and the arrangement of the valve block on the freight vehicle T can be increased. Then, it can contribute to the reduction of the manufacturing cost of the power unit 4.

A front cover 81 is provided in front of the power unit 4 in the present embodiment as a part of the cover 8. At least a part of the solenoid valve provided in this valve block (in this embodiment, the solenoid portion 41s in the main block 41) is provided on the front side of the valve block (main block 41 and sub block 42). According to this configuration, since the solenoid valve is located immediately after the front cover 81, the front cover 81 can prevent sand and mud rolled up by the rear wheels from colliding with the solenoid valve, and the solenoid valve is less likely to break down. .. This is very advantageous for the freight vehicle T, which often runs on unpaved roads.

Although one embodiment of the present invention has been taken up and described above, the present invention is not limited to the above-described embodiment. For example, the hydraulic actuator is not limited to the hydraulically driven cylinder as in the above embodiment, and may be a hydraulic motor. Further, the valve portion 35 can be supported only by the urging portion 36 without providing the spindle 34. Specifically, one end of the urging portion 36 can be connected to the piston 32 or the piston rod 33, and the other end of the urging portion 36 can be connected to the valve portion 35. Further, although the spindle 34 of the above embodiment is a separate body from the piston rod 33, the spindle 34 can also be formed as a part of the piston rod 33. Further, in the above-described embodiment, the protruding portion 331 of the piston rod 33 penetrates the piston 32 and protrudes toward the tip end side, but it is also possible not to penetrate or protrude. In this case, the protruding portion 331 can be formed as a part of the piston 32, or can be formed of another member (such as a rod) different from the piston 32 and the piston rod 33, and the protruding portion 331 formed in this way. The urging portion 36 can be guided in the axial direction.

Further, the shape (cross-sectional shape) of the downstream oil passage 311, the spindle 34, and the valve portion 35 is not limited to a circle, but may be a polygon. In this case, the outer edge of the valve portion 35 does not have to cover the entire outer edge of the downstream oil passage 311. In short, when the valve portion 35 covers the downstream oil passage 311, it suffices to cover the piston 32 to the extent that the amount of passing oil can be reduced so that the piston 32 can be decelerated.

Further, in the valve portion 35, another through hole for passing a small amount of hydraulic oil may be provided at a position different from the through hole 351 and the spindle 34. Further, the valve portion 35 is not provided with a through hole through which hydraulic oil can pass, and a bypass oil passage passing through the inside and outside of the cylinder tube 31 is provided by opening at a position not covered by the valve portion 35, for example, the inner surface of the recess 312. By connecting the recess 312 and the axial oil passage 3111 at positions outside the diameter of both, and configuring the bypass oil passage so as not to be blocked by the valve portion 35, a small amount of the bypass oil passage is passed through the bypass oil passage. It is also possible to pass the hydraulic oil of. When the bypass oil passage is provided in this way, the through hole 351 of the valve portion 35 is not essential. For example, when the spindle 34 is provided, the size of the through hole 351 can be set to the minimum size that the valve portion 35 can move with respect to the spindle 34, and the through hole 351 can be formed so that the hydraulic oil does not pass through. Further, when the spindle 34 is not provided, the through hole 351 can be prevented from being formed. Further, the recess 312 into which the valve portion 35 enters is provided in the cylinder tube 31 in the above embodiment, but the present invention is not limited to this, and the recess 32 may be provided. In this case, the valve portion 35 is provided on the distal end side of the concave portion provided on the piston 32 with respect to the proximal end side.

Further, in the above embodiment, the deceleration is set to start 3 ° before the load receiving table 1 becomes horizontal when the load receiving table 1 is deployed, but the valve portion with respect to the piston rod 33 in the free state of the biasing portion 36. By changing the position of 35, the angle at which deceleration is started can be set to another angle.

Further, although the speed reduction mechanism 3s of the above embodiment is configured to decelerate when contracting, it can also be configured to decelerate when extending. Further, the lift cylinder 2 may be provided with a reduction mechanism similar to that of the above embodiment.

Further, the load receiving platform elevating device Pg may be a model having only the lift cylinder 2 without the tilt cylinder 3.

Further, the load receiving table 1 may be configured to be foldable at an intermediate portion in the front-rear direction, and the intermediate portion may be folded and unfolded by a hydraulic actuator. In this case, the hydraulic actuator corresponds to the "hydraulic actuator that operates the load receiving platform 1".

Further, a cradle elevating device that is provided with a slide cylinder (not shown) as a hydraulic actuator for operating the cradle 1 for moving the cradle 1 in the front-rear direction of the vehicle and can store the cradle 1 under the floor of the freight vehicle T. The present invention can also be applied to Pg models. An example of the hydraulic circuit in this case is shown in FIG. The configuration of the main block 41 is the same as that of the embodiment (see FIG. 12). The sub-block 47 in the present embodiment includes a solenoid valve 472 for passing oil through the lift cylinder 2, a solenoid valve 473 that excites when the slide cylinder is extended, and a solenoid valve 474 that excites when the slide cylinder is contracted. Has been done. Filters 475, 476, and 477 are provided below the solenoid valve 472, to the right of the solenoid valve 473, and above the solenoid valve 474, respectively.

The sub-block side oil passage 471 branches from the collecting oil passage 471f located directly above the port 471a and the collecting oil passage 471f for passing oil to the lift cylinder 2 and extends to the port 471c, and extends to the solenoid valve 472 and the filter 475. The lift oil passage 471g where is located, branches from the collecting oil passage 471f to pass oil through the slide cylinder, and extends to ports 471d and 471e, and the slide expansion and contraction oil passage 471h where the check valve 479 and the flow control valve 480 are located. , The slide contraction oil passage 471i extending vertically by connecting the ports 471b and 471d, and the slide extension oil passage 471j extending vertically and horizontally by connecting the slide expansion and contraction oil passage 471h and the slide contraction oil passage 471i. ing. The slide contraction oil passage 471i is provided with a check valve 478 to prevent backflow toward the port 471b, and the slide contraction oil passage 471h is provided with a check valve 479 to prevent backflow in the directions of ports 471a and 471e. Has been done. When connecting the main block 41 and the sub block 47, ports 4143, 471a / 4144, 471b located at the connection portion between the two are connected, respectively. As described above, even if the sub-block 47 is changed, it is not necessary to newly provide an oil passage or a valve in the main block 41, and the main block 41 can be shared.

Further, in the above-described embodiment, one main block 41 and one sub-block 42 are used, but it is also possible to connect two or more sub-blocks 42 to one main block 41 to form a valve block. ..

Further, the sub-block 42 may be provided with only an oil passage and a port without any valve or filter.

Further, in the above-described embodiment, the number of ports for connecting the sub-block 42 in the main block 41 is 2 (ports 4143, 4144), but the number is not limited to this, and the number of ports can be 3 or more.

Further, the number of ports for connecting to the main block 41 in the sub block 42 may be smaller than the number of ports for connecting to the sub block 42 in the main block 41. In this case, the port of the main block 41 that is not used for connecting the sub block 42 is closed by attaching a plug or the like.

Further, in the above-described embodiment, regarding the solenoid valves 422, 423, 472, 473, 474 in the sub-blocks 42 and 47, 2-port 2-position switching type solenoid valves are provided in the oil passages for passing oil to each cylinder. Was being done. However, the configuration of the solenoid valve is not limited to this, and may be, for example, a switchable solenoid valve having 3 ports or more and 3 positions or more. Further, it may be a solenoid valve that allows oil to pass through only one of the lift cylinder 2, the tilt cylinder 3, and the slide cylinder. Further, it may be a solenoid valve that allows oil to pass through one or more of the lift cylinder 2, the tilt cylinder 3, and the slide cylinder. Further, a mechanism for shutting off oil flow to each cylinder can be added to these solenoid valves.

1 Cargo stand 2 Hydraulic actuator, lift cylinder 3 Hydraulic actuator, tilt cylinder 31 Cylinder tube 311 Downstream oil passage 3111 Axial extension of downstream oil passage 312 Recess 32 Piston 33 Piston rod 331 Protruding part 34 Spindle 35 Valve part 351 Through hole 352 Spring support recess 36 Bias part 3s Deceleration mechanism 4 Power unit 41 Valve block (main block)
411 Check valve 412 Relief valve 413 Solenoid valve 414 Main block side oil passage 4141 Port connected to oil supply pump 4143, 4144 Port connected to subblock side oil passage 415 Flow control valve 42 Valve block (sub block)
421 Sub-block side oil passages 4211, 4212 Ports connected to the main block 4213 Ports connected to the lift cylinder 4214 Ports connected to the tilt cylinder 422,423 Solenoid valve 43 Oil supply pump 44 Drive means, motor 45 Tank 8 cover 81 Front cover Pg Loading platform lifting device T Freight vehicle Rc Freight vehicle rear wheel axis

Claims (4)

It is a loading platform lifting device mounted on a freight vehicle, and adjusts the angles of the loading platform on which luggage is placed, the hydraulically driven lift cylinder for raising and lowering the loading platform, and the receiving platform. A hydraulically driven tilt cylinder connected to the pedestal and the freight vehicle side, and a power unit for supplying hydraulic oil to the lift cylinder and the tilt cylinder are provided.
The tilt cylinder can move in the axial direction of the piston rod toward the tip side of the cylindrical cylinder tube, the piston that reciprocates in the cylinder tube, the piston rod connected to the piston, and the piston. A valve portion provided and an urging portion for urging the valve portion toward the tip of the tilt cylinder are provided.
The cylinder tube is provided with a downstream oil passage on the tip side of the movable range of the piston.
The valve portion has a cross-sectional area larger than the cross-sectional area of the actual oil-passing portion of the downstream oil passage, and operates the downstream oil passage before the piston reaches the tip of the movable range. It is configured to cover the oil with a reduced amount of oil, allowing it to pass through.
The loading platform is deployed from an upright state by moving the piston in a direction reaching the tip of the movable range.
At the time of unloading, the cradle is unfolded, the upper surface of the cradle is leveled by the tilt cylinder, the cradle is lowered by the lift cylinder, and then the rear portion of the cradle is grounded by the tilt cylinder. Cylinder lifting device. A cargo cradle lifting device mounted on a freight vehicle, which includes a cradle on which luggage is placed, a hydraulically driven lift cylinder that raises and lowers the cradle, and a hydraulically driven tilt cylinder that adjusts the angle of the cradle. A power unit for supplying hydraulic oil to the lift cylinder and the tilt cylinder is provided.
The tilt cylinder can move in the axial direction of the piston rod toward the tip side of the cylindrical cylinder tube, the piston that reciprocates in the cylinder tube, the piston rod connected to the piston, and the piston. A valve portion provided and an urging portion for urging the valve portion toward the tip of the tilt cylinder are provided.
The cylinder tube is provided with a downstream oil passage on the tip side of the movable range of the piston.
The valve portion has a cross-sectional area larger than the cross-sectional area of the actual oil-passing portion of the downstream oil passage, and operates the downstream oil passage before the piston reaches the tip of the movable range. It is configured to cover the oil with a reduced amount of oil, allowing it to pass through.
The piston rod includes a spindle that projects in the axial direction of the piston rod from a surface on the tip side.
The downstream oil passage has a portion extending in the axial direction of the piston rod from the surface on the tip side of the piston rod in a state where the piston reaches the tip of the movable range.
The spindle enters the downstream oil passage with the piston reaching the tip of the movable range, and enters the downstream oil passage.
The valve portion is a load receiving platform elevating device having a through hole having a cross-sectional area larger than the cross-sectional area of the spindle through which the spindle penetrates. The load receiving platform elevating device according to claim 1 or 2, wherein the cylinder tube or the piston is provided with a recess into which the valve portion enters with the piston reaching the tip of the movable range. The urging portion is a coil spring.
The piston rod has a protruding portion protruding from the piston toward the tip end side, and the coil spring is fitted in the protruding portion.
The load receiving platform elevating device according to any one of claims 1 to 3, wherein a spring support recess in which the tip end portion of the coil spring is located is formed on the base end side of the valve portion.

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