JPH0519620Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention is installed at the entrance or exit or side or rear opening of a vehicle such as a bus or a truck, and is used to lift wheelchairs, cargo, etc. by the lifting and lowering movement of the platform. getting on and off,
The present invention relates to a lifting device for facilitating cargo handling.

(Prior Art and Problems) In recent years, lifting devices that have a parallel link mechanism attached to a main body frame fixed to the vehicle side and raise and lower a platform via the parallel link mechanism have been used for loading and unloading cargo and assisting wheelchair users in getting on and off the platform. It is beginning to be used in

By the way, in a lifting device that raises and lowers a platform using this type of link mechanism, when the platform is at its highest raised position, each link is at the upper limit position where it stands up almost vertically, and the hydraulic cylinder for driving the links at this time is The load is minimal and the moment of inertia of the platform due to the rotation of the link is large. As a result, unless some kind of countermeasure is taken, the elevated platform will forcefully collide with the vehicle side (boarding/exit or cargo loading port) and come to a halt, giving an undesirable impact to the wheelchair and cargo on the platform. Put it away.

(Means for solving the problem) In view of the above points, the present invention provides a means for slowing the rotation of the link before the platform reaches the raised position on the link side or the link drive side, so that the platform can be raised. The object of the present invention is to provide an elevating device that reduces the impact when the elevating device reaches the limit position.

In the present invention, a parallel link mechanism is provided on the main body frame fixed to the vehicle side, and the platform is raised and lowered via the parallel link mechanism, and the hydraulic cylinder for raising and lowering has a first chamber divided by a piston. a second chamber, the first chamber is supplied with hydraulic oil from a hydraulic source, and the second chamber is configured to move the piston into the first chamber when the second chamber is in a contracted state. A coil spring is disposed to urge the second chamber, and oil is supplied from an oil tank with an air breather to the second chamber through a parallel connection of a check valve and a flow rate restricting valve. The second chamber is filled with the oil, and restricts upward movement of the links of the parallel linkage mechanism at a speed at which the oil in the second chamber passes through the flow rate restrictor and returns to the oil tank with an air breather. The coil spring is configured to suppress rotation of the link of the parallel link mechanism when the link rotates close to the upper limit position, thereby solving the problems of the prior art.

(Function) In the lifting device of the present invention, hydraulic oil from a hydraulic source is supplied to the first chamber divided by the piston of the lifting hydraulic cylinder for rotationally driving the parallel link mechanism, and the hydraulic oil is supplied to the other second chamber. The oil from the oil tank with an air breather is supplied to the oil tank through a parallel connection of a check valve and a flow rate restricting valve, and the oil in the second chamber is filled with the oil. The movement of the link in the parallel link mechanism in the upward direction can be restricted by the speed at which the oil passes through the flow restrictor and returns to the oil tank with air breather. Achieving movement.

Further, a coil spring is arranged to urge the piston toward the first chamber when the second chamber of the lifting hydraulic cylinder is in a contracted state, and the coil spring pushes the link of the parallel link mechanism to the upper limit. The rotation of the link can be suppressed when the platform rotates close to the position, the rotation of the link is smoothly decelerated before the upper limit position, and the platform gently reaches the upper limit position. As a result, the impact when the platform hits the vehicle entrance or loading port is extremely small.

(Embodiment) Hereinafter, an embodiment of the present invention will be described by taking as an example a lifting device having a platform that can be folded into a staircase shape.

1 to 3 show the structure of the lifting device, and FIG. 4 shows an example of a bus as a vehicle to which the lifting device is installed.

As shown in FIG. 4, entrances 1 and 3 are provided on the side surfaces of the bus body 5, and opening/closing doors 7 and 9 are provided, respectively. The elevating device of the present invention is usually attached to the rear entrance 3.

As shown in Figs. 1 to 3, the elevating device is the entrance 3 of the bus body (the upper floor of the entrance is indicated by 3A).
A main body frame 10 fixed to the side, a side frame 11 supported so as to be able to rise and fall freely with respect to the main body frame 10 via a parallel link mechanism for elevating and lowering, an upper frame 12 integrated therewith, and a footboard 13
and a platform 16 having a first connecting plate 14 and a second connecting plate 15 pivotally connected on both sides thereof, and having a rear end pivotally connected to the upper frame 12.
, a footboard-cum-car stop plate 17 provided at the tip of the platform so as to be able to rise and fall freely, and a parallel link mechanism for deployment for changing the platform 16 from a folded step-like state to a flat-plate-like unfolded state.

The main body frame 10 is arranged on both sides of the entrance/exit 3, and one ends of a main arm 20 and a sub-arm 21, which form parallel links for elevating and descending, are pivotally supported (rotatably supported) thereon. That is,
The main arm 20 is fixed to a rotating shaft 22 that is supported by the main body frame 10, and the sub-arm 21 is attached to the main body frame 10 with a pin 23.
The other ends of the main arm 20 and the sub-arm 21 are pivotally attached (rotatably attached) to the side frame 11 with pins 24 and 25. The rotating shaft 22 to which the main arm 20 is fixed has a
As shown in FIGS. 2 and 3, a driving arm 26 is fixed, and a rod of a lifting hydraulic cylinder 27 is connected thereto. The rear end of the lifting hydraulic cylinder 27 is pivotally attached to the main body frame 10 side.

As a result, as the lifting hydraulic cylinder 27 extends and retracts, the upper frame 12 descends or rises while maintaining a horizontal state.

The connecting plate 14 of the platform 16, the tread plate 13 and the connecting plate 15, and the car stop plate 1 that also serves as a tread plate.
7 are connected to each other by a hinge or the like, and have a predetermined width and tread allowance so that they can form stairs at the entrance/exit. Bent portions 28 and 29 are formed on both sides of the footboard 13 and the connecting plate 15 for reinforcement.

The expansion parallel link mechanism includes a first link 32 pivotally connected between the upper frame 12 and the lower frame 31 and a second link 3 parallel to the first link 32.
3, and an expansion hydraulic cylinder 35 disposed between diagonal pivot points of four pivot points forming a parallelogram of these links 32 and 33.

As the expansion hydraulic cylinder 35 extends and retracts, the lower frame 31 rises or falls while maintaining a horizontal state.

At the tip of the lower frame 31, the tip of the platform 16 and a car stop plate 17 that also serves as a footboard are attached.
A connecting shaft 36 is pivotally supported on the lower frame 31, and a car stop hydraulic cylinder 40 for raising and lowering the car stop plate 17 is attached to the lower surface of the lower frame 31, and the tip rod of the cylinder 40 is connected to the car stop plate 17 bracket 41. has been done.

As shown in FIGS. 5 and 6, the lifting hydraulic cylinder 27 has a piston 81 slidably provided in a cylinder chamber inside an outer cylindrical body 80, a piston rod 82 connected and integrated with the piston 81, and The first and second chambers separated by a piston 81 are provided with oil supply and discharge ports 83A and 83B, respectively, similar to a double-acting hydraulic cylinder. Further, in order to return the piston 81 in the direction in which the piston rod 82 extends when the second chamber having the port 83B is in the contracted state,
A coil spring 84 is arranged in the second chamber.

As shown in the hydraulic circuit diagram of FIG.
Hydraulic oil is supplied to the first chamber through port 83A from a power unit PU serving as a hydraulic source, and oil is supplied to the second chamber through the port 83B from an oil tank 87 equipped with an air breather via a parallel connection of a check valve 85 and a flow rate throttle valve 86. In other words, unlike a normal single-acting hydraulic cylinder, the second chamber to the right of the piston 81 is always filled with oil.

In the configuration of the above embodiment, the lifting device is the first
In the state shown in the figure, the rod of the lifting hydraulic cylinder 27 is in the most retracted state, the lifting parallel link is in the raised position, and the upper surface of the upper frame 12 is approximately aligned with the upper floor surface 3A of the entrance/exit door 3. There is. Further, the deployment hydraulic cylinder 35 and the vehicle stopper hydraulic cylinder 40 are also in the retracted state, the lower frame 31 is in the lowered position, and the first connecting plate 14 is guided vertically and the footboard 13 is guided horizontally, so that the platform 16 is guided horizontally. The car stop plate 17, which also serves as a footboard, is horizontal and functions as a footboard. In this state, passengers can normally board and alight using the footplate 13 of the platform 16 and the footplate-cum-vehicle stop plate 17.

When lifting or lowering a wheelchair, etc., first extend the parking hydraulic cylinder 40 to raise the parking plate 17, then extend the deployment hydraulic cylinder 35, and raise the lower frame 31 by the deployment parallel link mechanism. let As a result, the platform 16 on the lower frame unfolds like a single flat plate as shown in FIG. After the platform 16 is fully expanded, the lifting hydraulic cylinder 27 is extended. The platform 16 is lowered by the force of the spring in the cylinder 27 and by gravity until it lands as shown in FIG.

In order to place a wheelchair or the like onto the platform 16 on which it has landed, the wheel stopper plate 17 must be in the down position. Therefore, after landing, the vehicle stop hydraulic cylinder 40 is retracted.

The operation of loading a wheelchair or the like onto the platform 16 from the ground and transporting it to the upper floor surface 3A of the entrance/exit can be accomplished by performing the above-mentioned reverse operation. In other words, the platform 1 is shaped like a single plate as shown in Figure 3.
Place a wheelchair, etc. on 6, and use hydraulic cylinder 4 to stop the vehicle.
0 is extended and the tip of the car stop plate 17 is raised, and the lifting hydraulic cylinder 27 is retracted. As a result, the main arm 20 in FIG.
Then, the sub-arm 21 rotates clockwise, and the platform 16 rises. At this time, the speed at which the oil in the second chamber (the right chamber) of the piston 81 of the lifting hydraulic cylinder 27 passes through the flow rate restricting valve 86 and returns to the oil tank 87 corresponds to the speed at which the hydraulic cylinder 27 contracts. is limited. That is, the main arm 20
The rotation speed in the upward direction will be limited,
In consideration of the case where a wheelchair or the like is on the platform 16, the platform 16 is gradually raised. And platform 1
6 approaches the highest position, the second chamber of the cylinder 27 contracts and the coil spring 84
As a result, the platform 16 is smoothly decelerated when it approaches the upper limit position, and the impact when it hits the floor end of the entrance/exit can be sufficiently weakened. Therefore, a large impact is not given to wheelchairs etc. on the platform, and the platform can be smoothly raised.

In the above-mentioned embodiments, the platform has a structure that can be folded in a stepwise manner, but the present invention is also applicable to a structure in which a single flat platform is raised and lowered by a parallel link mechanism.

(Effects of the invention) As explained above, according to the invention, in a configuration in which a parallel link mechanism is provided on the main body frame fixed to the vehicle side and the platform is raised and lowered via the parallel link mechanism, the parallel link mechanism is In addition to devising the structure of the lifting hydraulic cylinder that drives the platform up and down through the platform, a check valve and a flow rate restricting valve are installed in parallel in the second chamber on the opposite side of the first chamber to which the hydraulic oil for the cylinder is supplied. Since oil is supplied from the oil tank with air breather through the connection, the platform can be moved up and down gently in consideration of loading wheelchairs, etc. onto the platform, and the platform is at the upper limit position. It is possible to obtain an elevating device that can reduce the impact when

[Brief explanation of the drawing]

Fig. 1 is a side view of an embodiment of the lifting device according to the present invention, in which the platform is in the form of stairs;
Figure 3 is a side sectional view of the platform in its unfolded state, Figure 3 is a side sectional view of the platform in its landing state, Figure 4 is a side view showing a bus as a vehicle equipped with a lifting device, and Figure 5 is an embodiment of the present invention. FIG. 6 is a longitudinal sectional view showing the lifting hydraulic cylinder used, and FIG. 6 is a hydraulic circuit diagram. 1, 3... Entrance/exit, 10... Body frame, 1
1...Side frame, 12...Upper arm, 13...Tread plate, 14, 15...Connection plate, 1
6...Platform, 17...Car stop plate, 20
...Main arm, 21...Sub arm, 27...
... Hydraulic cylinder for lifting, 31 ... Lower frame, 32, 33 ... Link, 35 ... Hydraulic cylinder for deployment, 40 ... Hydraulic cylinder for car stop, 86
...Flow rate restrictor, 87...Oil tank with air breather.

Claims (1)

[Claims for Utility Model Registration] A parallel link mechanism is provided on the main body frame fixed to the vehicle side, and the links constituting the parallel link mechanism are rotationally driven by a lifting hydraulic cylinder. In the lifting device for lifting and lowering, the lifting hydraulic cylinder includes a first chamber and a second chamber separated by a piston, hydraulic oil from a hydraulic source is supplied to the first chamber, A coil spring is disposed in the second chamber to urge the piston toward the first chamber when the second chamber is in a contracted state, and a check valve and a flow rate restricting valve are disposed in the second chamber. The second chamber is filled with oil by being supplied with oil from an oil tank with an air breather through the parallel connection of the oil tank, and the oil in the second chamber passes through the flow rate restricting valve to The movement of the link in the parallel link mechanism in the upward direction is restricted by the speed of returning to the breather oil tank, and the rotation of the link is controlled by the coil spring when the link of the parallel link mechanism rotates to near the upper limit position. A lifting device characterized by suppressing.