JPH0251773B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a truck, and more particularly to a truck that can raise and lower the loading platform while keeping it horizontal and also tilt or dump the loading platform rearward.

For freight vehicles, if the loading platform can be raised and lowered while remaining horizontal during loading, and if it can be dumped when unloading, it will be easier to load and unload cargo, and dangerous work can be avoided; It would be desirable to see a freight vehicle equipped with a loading platform that can carry cargo.

Dump vehicles are well known, and freight vehicles that can raise and lower the cargo bed while keeping it horizontal have also been proposed, but a combination of the two is unknown. In particular, current vehicles that can raise and lower the loading platform require a lift frame between the loading platform and the chassis frame on the vehicle body to raise and lower the loading platform.
If they are simply combined, the structure will be complicated and the space occupied by the mechanism will be large.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a freight vehicle which can not only be raised and lowered while remaining horizontal on a loading platform, but also can be dumped without the need for a lift frame.

In order to achieve this objective, according to the present invention,
A pair of legs are fixed to the front and rear of the loading platform, each leg is provided with a hydraulic cylinder, and the legs are made to extend and retract by the operation of the cylinder, and the lower ends of the pair of legs at the front of the loading platform are It is placed on the chassis frame of the main body of the vehicle, and the lower ends of the pair of legs at the rear of the loading platform are pivoted to the front chassis frame so that the loading platform can be dumped. A dumping mechanism consisting of a dumping hydraulic cylinder and a link is provided between the chassis frame and the loading platform at a position approximately in the center of the loading platform, and the loading platform is attached to the chassis frame by the mechanism and the legs, and the legs extend and retract. A hydraulic circuit is provided for supplying hydraulic oil to the dump cylinder and the dump cylinder, and this hydraulic circuit includes one hydraulic pump and a directional control valve,
By switching the directional switching valve from the outside, the lifting/lowering of the loading platform or the dumping operation of the loading platform is selectively performed. and a second direction switching valve that switches the direction of the hydraulic oil supplied to the leg extension/retraction hydraulic cylinder. A replenishment circuit is provided for supplying pressurized oil to the dumping cylinder so that the piston can be raised, and the replenishment circuit is configured to supply the dumping cylinder with pressure oil so that the piston can be lowered even when the leg is shortened. A truck is provided that has a cargo platform that can be lifted, lowered, and dumped, and is replenished with pressure oil discharged from cylinders for extending and retracting legs.

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show an overall view of a truck having a cargo platform that can be raised and lowered and dumped according to the present invention. A pair of legs 3, 3 and a pair of legs 4, 4 are fixed to the front and rear parts of the loading platform 1, respectively. Each of these legs contains a hydraulic cylinder that extends each leg or returns the extended leg. The lower ends of the front legs 3, 3 are placed on a chassis frame 5 (more specifically, a subframe 6 fixed to the chassis frame 5) of the truck body. In this regard, referring to FIG. 4, the lower end 7 of leg 3
is merely inserted into a hole 9 formed in a guide plate 8 fixed to the subframe 6, and is not fixed. This lower end 7 is approximately
It is inserted about 40mm and will not come off even if the load is on one side when the loading platform is raised or lowered.

Further, the lower ends of the rear legs 4, 4 are pivotally supported to the subframe 6 (and thus the chassis frame 5). In FIG. 4, a pin 10 connects the leg 4 and the subframe 6. This pin 10 may be supported by a bracket 11 fixed to the subframe 6. Therefore, the loading platform 1 can raise the front part around the pin 10 and tilt the entire loading platform rearward, that is, can be dumped.

A dumping hydraulic cylinder 13 and its link 14 are provided at approximately the center of the lower surface of the loading platform between the loading platform frame 12 and the subframe 6 (and eventually the chassis frame 5) which are fixed to the lower surface of the loading platform. Since this dumping mechanism is well known, detailed explanation will be omitted. Briefly, the lower end of the hydraulic cylinder 13 is pivotally supported by the chassis frame 6, and the triangular plate 15 of the link mechanism 14
One end is pivotally supported on the carrier frame 12, and when the piston rod 16 is extended as shown in FIG. 6, the carrier 1 is dumped with the aid of an auxiliary rod 17.

FIG. 7 shows a case where the hydraulic cylinders for extending and retracting the legs built into the legs 3 and 4 are operated, and the platform 1 can be raised while remaining horizontal. As shown in FIGS. 6 and 7, the loading platform 1 is connected to the chassis frame 5.
When the legs 3 and 4 are further separated, the oil pipes that supply pressure oil to the hydraulic cylinders built into the legs 3 and 4 also rise up. For this reason, as shown in FIG. When the loading platform 1 is connected and does not separate from the chassis frame 5, it is slightly slackened as shown by the solid line in FIG. In this case, the guide 20 is
Its downward rotation angle is determined and has a certain length to prevent it from hanging downward.
When the loading platform 1 rises, the guide 20 rotates upward as shown by the chain line, and the joint 21 also rotates upward.
It rotates as 9 is pulled up. Therefore, loading platform 1
The oil pipe 19 can follow the dumping and rising of the fuel without any problem.

A driver's seat 23 of the vehicle body is provided with an operating lever 24 for raising and lowering the cargo platform 1 while keeping it horizontal or dumping it. Three levers are shown in the diagram, one of which is used to transmit the rotational force of the engine to the hydraulic pump, and the other two are used for dumping and the other for raising and lowering the hydraulic pump. The loading platform 1 can be dumped by sending pressure oil to the cylinder 13, or the loading platform 1 can be raised and lowered while remaining horizontal by sending pressure oil to the hydraulic cylinders for extending and contracting the legs 3 and 4. In addition, the loading platform 1 cannot be used for both lifting and dumping.
Two of the levers 24 are configured so that they can only be moved selectively.

A hydraulic circuit is provided to operate the hydraulic cylinder for extending and retracting the legs or the hydraulic cylinder for dumping. This hydraulic circuit is shown in FIG. In FIG. 8, power taken out from the engine 25 via the transmission mechanism 26 drives one hydraulic pump 27 to supply pressure oil from a tank 38 to the circuit via a filter 39. In the transmission mechanism 26, power transmission and interruption thereof are controlled by one of the levers 24 shown in FIG. Further, two 6-port 3-position directional switching valves 28 and 29 are provided in the circuit, one switching valve 28 is used to control the dump hydraulic cylinder 13, and the other switching valve 28 is used to control the dump hydraulic cylinder 13.
Reference numeral 9 is used to control the leg extension/retraction hydraulic cylinders 30 provided on the front and rear legs 3 and 4.

First, the control circuit section of the dump hydraulic cylinder 13 will be explained. A pipe 30' extends from the switching valve 28 and leads via a pilot check valve 31 to a port 32 of the hydraulic cylinder 13 on the opposite side from the piston rod 16. The opening and closing of the pilot check valve is controlled by the hydraulic pressure of a hydraulic pump. A pipe 34 extending from a port 33 on the rod 16 side of the piston cylinder 13 returns to the pipe 30 via a check valve 35. A branch pipe 37 is provided in the pipe 34' so as to pass through another check valve 36, and this check valve 36 is designed so that it will not open unless the hydraulic pressure is stronger than that of a normal check valve such as the check valve 35. There is. For example, if the check valve 35
If it is 0.5Kg/ ^cm2 , check valve 36 at 1Kg/ ^cm2 .
is starting to open. Pipe 37 is oil tank 38
Excess oil is returned to the tank. tube 34 and tube 37
A pipe 40 is further provided at the branch point of the pipe 40.
is connected to a port on the opposite side of the switching valve 28 from the pipe 30'. This pipe 40 is also connected to similar ports of other switching valves 29, and is further connected to a pipe 42 extending from the hydraulic pump 27 via a relief valve 41. The pipe 42 is the switching valve 2
8, and further connected to an adjacent port via a branch pipe 43 and a check valve 44. Further, the pipe 43 is further branched and connected to a similar port of the switching valve 29 via a check valve 45.

Next, in the circuit for the hydraulic cylinder 30 for extending and retracting the legs, a pipe 46 extends from a port on the opposite side from the pipes 40 and 43 of the switching valve 29, and three throttles 47,
It is sent to each hydraulic cylinder 30 via 48 and 49. Each hydraulic cylinder 30 is provided with a pilot check valve mechanism 50 to control the inflow and outflow of pressure oil. Pressure oil from the port on the side where the piston rod of each hydraulic cylinder 30 extends is connected through one pipe 51 to another port of the switching valve 29.

The central port of the directional control valve 28 and the central port of the directional control valve 29 are connected by a pipe 52, and a pipe 53 is connected from the port on the opposite side of the directional control valve 29.
is extended, and this tube 53 returns to the tank 38. This circuit consisting of the pipes 42, 52, 53 works effectively to eliminate the burden on the pump 27 in the event of an engine stall, etc., but it is not essential, and the circuit consisting of the pipes 42, 52, and 53 is The port valve may be replaced with a 4-port valve.

The positions of the directional control valves 28 and 29 are switched by operating a lever 24 provided at the driver's seat. These operations will be explained using FIGS. 9 to 13.

First, when the directional control valves 28 and 29 are not in operation, such as when driving, the lever 2
4, both are in the right position. While the weight from the loading platform is applied to the piston rod 16 of the dump hydraulic cylinder 13, the pressure oil from the pump 27 is returned to the port 33 on the rod side of the hydraulic cylinder 13 via the relief valve 41, pipe 40, and pipe 34. The piston is forced in a downward direction.
In this case, pilot check valve 31 is open and pipe 30' is in communication with pipe 40, which further assists in forcing and prevents the platform from dumping.

The directional control valve 29 supplies the pressure oil from the pump 27 to the leg extension/retraction hydraulic cylinder 3 via the pipe 43 and the pipe 51.
0 is forced into a contracted state, and the escape oil is drained into pipe 4.
6 and returns to the tube 40. Therefore, when not in operation, all the hydraulic cylinders are forced into a retracted state, and the loading platform 1 is strongly supported so as not to move upwardly away from the chassis frame 5 even if there is vibration during traveling.

FIG. 10 shows the state of the loading platform 1 when the dump truck is raised. The directional control valve 28 is moved from a central neutral position to a left-hand position. pump 2
Pressure oil from 7 is sent to port 32 of hydraulic cylinder 13 via pipe 43, pipe 30', and pilot check valve 31 to push piston rod 16 upward. Escaping oil from port 33 is returned to the tank via pipe 34 and check valve 36. Note that since pressure oil is applied to the check valve 35, passage of oil from the pipe 34 is blocked. Furthermore, the relief valve 41 creates an escape for pressure oil when switching from the non-operating position shown in FIG. 9 to when the dump truck is raised as shown in FIG. 10, thereby making the switching smooth. The action of this relief valve also works in the same way when the other switching valves 29 are switched.

In order to stop the tilting of the loading platform, the directional control valve 28 may be stopped at the center position shown in FIG. As a result, no pressure oil is applied to the hydraulic cylinder 13, and leakage of pressure oil from the port 32 is also prevented by the check valves 31 and 35. In addition, in FIG. 8, the other directional control valve 29 is also in the neutral position, but this illustration is for convenience of explanation.
It should be understood that the switching valve 29 is in the right-hand position as shown in FIG.

Next, in order to lower the dumped cargo platform, the first
As shown in FIG. 1, the switching valve 28 is moved to the right position. The rod 16 is lowered by the weight of the loading platform, and the pilot check valve 31 is turned off by the pump 2.
7 is opened, and pressure oil is sent to the pipe 40. Pressure oil from pipe 40 is returned to hydraulic cylinder 13 via port 33. Therefore, the loading platform 1 descends due to its own weight. In this case, the pressure oil from the pump 27 passes through the relief valve 41 to the pipe 40 and then via the check valve 36 to the tank 38. Check valve 3
5 is pressed by pressure oil when the rod descends, so it hardly opens.

FIG. 12 shows a state in which the loading platform is raised while keeping it horizontal. The directional valve 29 is in the left-hand position. (Note that the dumping directional control valve 28 is in the right position. This is also the case during stopping and lowering, which will be explained next.) Pressure oil from the pump 27 is supplied to the hydraulic pressure for each leg extension and contraction via a pipe 46. The piston of the cylinder 30 is pushed to extend the legs, and the escape pressure oil is returned to the pipe 34 via the pipe 51 and the pipe 40.

That is, the pressure oil discharged from the leg extension/retraction hydraulic cylinder is returned to the dump hydraulic cylinder 13. This allows the dump hydraulic cylinder 13 to move freely in the upward direction. This is the seventh
As shown in the figure, when the loading platform rises, the rod 16 of the dumping hydraulic cylinder 13 is pulled up as the loading platform rises, so if the movement of the dumping cylinder 13 is not smooth, the lifting of the loading platform 1 will be suppressed. It is. In particular, when the piston rod 16 is pulled, if the oil from the port 33 is simply returned to the port 32, there will be insufficient oil to the cylinder on the port 32 side by the volume occupied by the rod 16, which will prevent the cargo platform from rising. It acts like this.

Cylinder 3 mentioned above eliminates this drawback.
0 to the pipe 40. According to this, the pressure oil is forced to be sent to the port 32 through the check valve 35, so that it acts to push up the piston, thereby preventing the dumping hydraulic cylinder 13 from acting as a blocking action. In particular, check valve 35 and check valve 36 have different control pressures, and check valve 36 is larger, so it has the advantage that a pushing force acts on the piston, although it is not as strong as described above. , check valve 3 for excess oil.
6 and returned to tank 38.

To stop the lift, the directional control valve 29 is returned to the neutral position, as shown in FIG. (Also in this case, the other switching valve 28 is not in the position shown in FIG. 8 but in the right position shown in FIG. 12, as described above.) Switching valve 29
When in the neutral position, oil supply and discharge are stopped and the leg telescoping hydraulic cylinder 30 remains stationary. Further, the pressure oil from the pump 27 is returned to the tank 38 through the relief valve 41, the pipe 40, and the check valve 36.

FIG. 13 shows the loading platform when it is lowered. The loading platform 1 tries to push the piston of the hydraulic cylinder 30 for extending and retracting the legs by its own weight, but this is restricted by the throttles 47 to 49, so pressure oil is supplied from the pump 27 through the pipe 51, and the piston is pushed in the retracting direction. Press.
The escape pressure oil reaches the pipe 40 from the pipe 46 and is supplied from the pipe 40 to the port 33 via the pipe 34. Also, the pilot check valve 31 is opened by the pressure of the pump 27, and the oil from the port 31 is transferred to the pipe 30'.
is returned to tube 40 via. That is, here as well, the pressure oil from the leg extension/retraction hydraulic cylinder 30 is used to assist the lowering of the dump hydraulic cylinder 13, and therefore the dump hydraulic cylinder 13 has a blocking action when the platform is lowered. Not only does it disappear, but this also promotes downward movement. In this case, if the loading platform is to be lowered by an impact, adjustment can be made using the throttles 47 to 49.

As clarified above, according to the configuration of the present invention, the loading platform can perform dumping operations and elevation in a horizontal position using the front and rear legs and the dumping mechanism without the need for a subframe such as a lift frame. In addition, since the dumping operation and horizontal elevation are performed selectively, only one pump is required for the hydraulic circuit, which simplifies the hydraulic circuit configuration, making manufacturing, assembly, and repair easier, and lowering the price. can also be kept low. and,
According to the present invention, the hydraulic circuit with the replenishment circuit eliminates the effect of interfering with the lifting and lowering of the dump cylinder when the loading platform is raised and lowered in a horizontal position, thereby ensuring smooth raising and lowering.

[Brief explanation of the drawing]

FIG. 1 is a side view of a truck according to the present invention having a cargo platform that can be lifted and dumped, and FIG.
FIG. 3 is a rear view of the truck shown in FIG. 1, FIG. 4 is a partial side view showing details of the loading platform, FIG. 5 is an explanatory diagram showing the connection of the oil pipe, Fig. 6 and Fig. 7 are side views of the freight vehicle showing when the cargo platform is dumped and when the cargo platform is raised and lowered, respectively, Fig. 8 is a circuit diagram showing the configuration of the hydraulic circuit, and Figs. FIG. 4 is an explanatory diagram showing the state of the hydraulic circuit when the dump truck is dumped, when the dump truck is lowered, when the loading platform is raised, and when the loading platform is lowered. DESCRIPTION OF SYMBOLS 1... Loading platform, 3... Front leg, 4... Rear leg, 5... Chassis frame, 6... Subframe, 7... Lower end of front leg, 8... Guide plate, 10
... Pivot pin, 12 ... Loading platform frame, 13 ...
Dump hydraulic cylinder, 14...link, 19...
... Oil pipe, 20 ... Guide, 21 ... Swivel joint, 23 ... Driver's seat, 24 ... Switching lever, 25 ... Engine, 27 ... Hydraulic pump, 2
8, 29...Directional switching valve, 30...Hydraulic cylinder for leg extension/contraction, 31...Pilot type check valve, 2
8...Tank, 41...Relief valve.

Claims (1)

[Scope of Claims] 1. A pair of legs are fixed to the front and rear of the loading platform, each leg has a built-in hydraulic cylinder, and the legs are made telescopic by the action of the cylinder. The lower ends of the pair of legs are placed on the chassis frame of the vehicle body, and the lower ends of the pair of legs at the rear of the loading platform are pivoted to the front chassis frame so that the loading platform can be dumped. A dumping mechanism consisting of a dumping hydraulic cylinder and a link is provided between the lower surface of the loading platform and the chassis frame at a position approximately in the center of the loading platform, and the loading platform is attached to the chassis frame by the mechanism and the legs. A hydraulic circuit is provided for supplying hydraulic oil to the telescopic cylinder and the dump cylinder, and this hydraulic circuit includes one hydraulic pump and a directional switching valve, and the directional switching valve can be switched from the outside. The directional control valve is configured to selectively perform lifting and lowering of the loading platform or dumping operation of the loading platform, and the directional switching valve includes a first directional switching valve that switches the direction of hydraulic oil supplied to the dump hydraulic cylinder, and a first directional switching valve that switches the direction of hydraulic oil supplied to the dumping hydraulic cylinder; and a second directional switching valve that switches the direction of hydraulic oil supplied to the hydraulic cylinder, and the hydraulic circuit includes a second direction switching valve that switches the direction of hydraulic oil supplied to the hydraulic cylinder. A replenishment circuit is provided for supplying the piston so that it can be raised, and this replenishment circuit also operates when the leg is shortened.
A truck having a cargo platform that can be raised and lowered and dumped, characterized in that the dumping cylinder is supplied with pressurized oil discharged from a leg extension/retraction cylinder so that its piston can be lowered. 2 In order to maintain the connection of the oil pipe connected to the hydraulic cylinder for extending and retracting the legs when the loading platform is raised, the oil pipe has a guide that is pivotally supported on the chassis frame on the vehicle body side, and the oil pipe is connected to this guide. 2. Truck according to claim 1, characterized in that it is loosely attached.