JP3397309B2 - Tailgate lifter hydraulic circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit for a tailgate lifter. A hydraulic circuit that can ensure a safe work especially when the gate plate drive mechanism of the tailgate lifter has a problem and is forcibly manually pushed up to store it in the rear part of the door Is.

[0002]

2. Description of the Related Art FIG. 6 shows a tailgate lifter using a parallelogram link mechanism A. In FIG. 6, a frame 22 is fixed to the lower rear portion of the chassis 21 of the van type vehicle. A rotary shaft 23 is rotatably supported by the frame 22, and the rotary shaft 23 is driven by a hydraulic cylinder 24 housed in the frame 22 to rotate. Rotating side plates 25 are fixed to both sides of the rotating shaft 23. One end of a tension arm 26 is pivotally attached to the frame 22 by a pin 27, and a lift arm is attached to the rotary side plate 25.
One end of the frame 28 is pivotally attached by a pin 29. The other end of the tension arm 26 has a vertical arm 30.
At the same time, it is pivotally attached to the gate plate B, and the other end of the lift arm 28 is pivotally attached to the lower end of the vertical arm 30 by a pin 31.

The elevating device constructed as described above performs the cargo handling work by raising and lowering between the rear end of the bed floor surface D and the ground C with the gate plate B horizontal, and the rear door E which is closed during traveling. The gate plate B is swung up by approximately 90 ° by the opening / closing hydraulic cylinder 32 so as to be stored face to face and stored.

When the gate plate B of such a tailgate lifter is closed to forcibly store it manually as shown in FIG. 7 (a) (in principle, it is not allowed to manually close the gate plate, but the gate plate is not available at the destination. In the case where the operation of B is unsuccessful and cannot be stored, the operator may be forced to push it up to store it, and the rod 32 'of the opening / closing hydraulic cylinder 32 (Fig. 7a) is forcibly pulled. Then, since the stop valve 33 is closed, no oil is supplied, so that the hydraulic cylinder 32 is in a vacuum state.

In this state, when the lock of the gate plate of the tailgate lifter is released, the rod 3 of the hydraulic cylinder 32 is released.
2'returns rapidly and the gate plate rotates rapidly (Fig. 8 ・
b). This is extremely dangerous for workers.

Incidentally, FIG. 9 shows an example of a locking device for a tailgate lifter for which a patent application has been filed by the present applicant. In this locking device, a lock bar mounting bracket 35 is projected rearward on a rear surface of a side pillar 34 to which a rear door E is hinged, and a lock bar 36 orthogonal to the lock bar mounting bracket 35 is provided at a tip end of the lock bar mounting bracket 35. Installed.

On the other hand, on the gate plate side of the tailgate lifter, a slide bar 37 which slides laterally on the side edge thereof.
And have. A lock bracket 39 having a hole 38 into which the lock bar 36 is fitted is formed at the end of the slide bar 37 at a right angle.

Therefore, when the gate plate is stored, if the slide bar 37 is slid sideways to fit the lock bar 36 into the hole 38 of the lock bracket 39, the gate plate B will not return to the rear.

In order to prevent the rod 32 'of the hydraulic cylinder 32 from suddenly returning when the lock is released, there is also a method of electrically controlling the stop of the gate plate B by using a limit switch or the like. However, since the gate plate B is attached to the rotating portion, there are (1) wiring arrangement problem, (2) limit switch durability problem, (3) cost problem, etc., and improvement thereof is desired. ing.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a tailgate lifter capable of reliably and safely stopping the gate plate at the storage position without requiring any special operation.

[0011]

Therefore, a tailgate lifter according to the present invention is provided with a pipeline connected between an opening / closing hydraulic cylinder for opening / closing a gate plate and an oil tank via an opening / closing solenoid valve, and the opening / closing. A tailgate lifter having a hydraulic oil cylinder and a conduit connected to the oil tank via a check valve, wherein the opening / closing solenoid valve can be switched between a conduction position and a position for blocking oil flow. Yes, the check valve is held in the “closed” state when the gate plate is closed by the motor when the motor is operating, and is “open” when the gate plate is manually stored when the motor is not rotating. And supply the oil in the oil tank to the opening / closing hydraulic cylinder,
It is characterized in that a vacuum inside the hydraulic cylinder for opening and closing is prevented. Further, another tailgate lifter of the present invention is characterized in that a hydraulic circuit including the oil tank, the motor, and the opening / closing solenoid valve is formed into a power pack. In still another tailgate lifter according to the present invention, the check valve is provided outside the power pack.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A description will be given with reference to FIGS. Figure 1
a is a principle diagram of the safety hydraulic circuit of the present invention. 1 is an oil tank. The oil tank 1 is connected via an opening / closing solenoid valve 9 to an opening / closing cylinder 15 (corresponding to the opening / closing cylinder 32 in FIG. 6) of the gate plate (a known hydraulic circuit such as a hydraulic pump is omitted). The open / close solenoid valve 9 can be switched between a conduction position and a position for blocking the flow of oil. A feature of the present invention is that a pipeline e with a check valve 11 that allows oil flow only in the direction from the tank 1 to the open / close cylinder 15 is provided in the pipeline connecting the open / close solenoid valve 9 and the open / close cylinder 15. In point. The check valve 11 has a function of a safety valve that opens when the opening / closing cylinder 15 is sucking oil and closes when the oil is not sucking oil.

Therefore, as shown in FIG. 1B, when there is a malfunction in the operation of storing the gate plate B, the operator may be forced to manually push up the gate plate B. (The arrow in FIG. 1b), the rod 15 'of the opening / closing cylinder 15 is forcibly pulled at this time (FIG.
a arrow). Then, although the opening / closing solenoid valve 9 is in the closed position, the oil flows from the tank 1 through the check valve 11 due to the existence of the safety check valve 11, and is sucked by the opening / closing cylinder 15 so that the cylinder 15 is evacuated. Prevent.

Referring to FIG. 2, since the oil in the open / close cylinder 15 once sucked in FIG. 1A does not flow backward in the reverse direction by the check valve 11, the oil in the open / close cylinder 15 remains as it is. This acts as a cushion, and the rod 15 'cannot return even if it tries to return. That is, the safety is maintained and the situation where the gate plate B is suddenly inverted (opened) does not occur. In addition, to release this state,
Although not shown, the push button switch, which is separately provided, is pushed to open the switch.

FIG. 3 is a hydraulic circuit diagram of a tailgate lifter having the safety circuit described with reference to FIGS. 1 and 2.
In FIG. 3, a block Q surrounded by a chain line is a manifold block. In the manifold block Q, a safety circuit including the check valve 11 described in FIG. 1 is built in. The manifold block Q is housed inside a power pack (a drive circuit for driving a gate plate is packed) P. In FIG. 3, 1 is an oil tank, 2 is a suction filter, and the oil is sucked by a hydraulic pump 3 driven by a motor 4 through this. The pressure oil discharged from the hydraulic pump 3 reaches the shuttle valve 5.

From the shuttle valve 5 to the tank 1 via the relief valve 6, a line a, a line b connected to the lifting solenoid valve 8 and the opening / closing solenoid valve 9, and a line connecting to the return flow control valve 7. It is branched and connected to c. A check valve 11 is connected by a conduit e between the outlet of the flow control valve 7 provided on the conduit c and the conduit d on the outlet of the opening / closing solenoid valve 9.

The above is the configuration of the power pack P, which can be attached to any place. From the lift solenoid valve 8 via the conduits f and g, further via the solenoid valve 12 the lift hydraulic cylinder 13, and from the opening / closing solenoid valve 9 via the conduits d and e, and the opening / closing speed. It is configured so that it can be connected to an opening / closing hydraulic cylinder 15 via an adjustment throttle valve 14. In the figure, 10 is an air breather provided in the tank.

FIG. 4 shows another example of the hydraulic circuit including the safety circuit of the present invention in the power pack P as in FIG. Also in this circuit, the circuit of the present invention is provided on the side of the opening / closing hydraulic cylinder 15 that presses the piston. In this example as well, the return flow control valve 7 on the outlet side from the shuttle valve 5 via the pipe line c and the outlet side pipe line d on the opening / closing solenoid valve 9 are connected.
And the check valve 11 is connected to the pipe line e.

Unlike the example of FIGS. 3 and 4, FIG. 5 is provided with a check valve 11 of the present invention outside the power pack P. In this case, the pipe line i connected to the tank 1 is connected to the pipe line d connecting the opening / closing solenoid valve 9 and the throttle valve 14 for opening / closing speed provided in the circuit branched from the shuttle valve 5. A check valve 11 is provided in the pipeline i.

(Operation) As described above, the check valve 11 is provided in the opening / closing circuit inside the manifold block Q in the power pack P. Due to this, the check valve 11 remains closed during normal closing operation (pushing the operation switch to rotate the motor and pumping oil), and only when the motor is manually closed when the motor is not rotating. Since the check valve 11 opens and the oil in the tank 1 is sucked into the hydraulic cylinder 15 for opening and closing, the gate plate B may not operate in some cases, and even if an operator pushes it up and stores it, the hydraulic tank Since the oil in 1 is supplied to the opening / closing hydraulic cylinder 15 via the check valve 11, the inside of the opening / closing hydraulic cylinder 15 does not become a vacuum, and when the gate plate lock of the tailgate lifter is released, the gate plate suddenly opens. You can avoid the unexpected accident from happening.

[0021]

According to the first aspect of the present invention, the gate plate B can be manually closed without stopping, and a sudden opening operation that occurs when the gate plate lock of the tailgate lifter is unlocked can be prevented. Therefore, an accident can be prevented. It is possible to secure safety. According to the second or third aspect, it is possible to provide the power pack with the safety circuit provided inside or outside the power pack in advance, so that it is possible to provide the vehicle with the tailgate lifter that is safe for the operator even in an emergency.

[Brief description of drawings]

FIG. 1 shows a circuit diagram of the principle of the present invention.

FIG. 2 shows a state in which the gate plate is forcibly lifted in FIG.

FIG. 3 is a first example including the hydraulic circuit of the present invention.

FIG. 4 is a second example of the same.

FIG. 5 shows an example in which a safety circuit is provided outside the power pack.

FIG. 6 is a side view of a known tailgate lifter.

FIG. 7 is a hydraulic circuit diagram of a known tailgate lifter.

FIG. 8 is a diagram showing a danger when the valve is forcibly closed.

FIG. 9 is a diagram showing an example of a lock device for a tailgate lifter.

[Explanation of symbols]

1 oil tank 2 suction filter 3 gear pump 4 motor 5 shuttle valve 6 relief valve 7 return flow control valve 8 lift solenoid valve 9 open / close solenoid valve 10 air breather 11 check valve 12 solenoid valve 13 lift hydraulic cylinder 14 open / close speed adjustment Throttle valve 15 Hydraulic cylinder for opening and closing

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B60P 1/44 F15B 11/02 F15B 20/00 B62D 33/02

Claims (3)

(57) [Claims] 1. A pipe line connecting an opening / closing hydraulic cylinder for opening / closing a gate plate and an oil tank via an opening / closing solenoid valve, and a check valve between the opening / closing hydraulic cylinder and the oil tank. A tailgate lifter having a pipe line connected through the opening / closing solenoid valve, wherein the opening / closing solenoid valve can be switched between a conduction position and a position for blocking the flow of oil, and the check valve is used when the motor operates. Is held in the closed position when the motor is closed to the storage position, and it is opened when the gate plate is manually stored when the motor is not rotating, and the oil in the oil tank is opened and closed for opening and closing. A tailgate lifter, characterized in that it is supplied to a hydraulic cylinder to prevent a vacuum inside the opening / closing hydraulic cylinder. 2. The tailgate lifter according to claim 1, wherein a hydraulic circuit including the oil tank, the motor, and the opening / closing solenoid valve is formed as a power pack. 3. The tailgate lifter according to claim 2, wherein the check valve is provided outside the power pack.