JP2002364604A - Cylinder synchronization device of gate lifter provided with gate sinking prevention mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylinder synchronization device of a gate lifter provided with a gate sinking prevention mechanism capable of automatically correcting deviation of expansion amount of right and left hydraulic cylinders and preventing sinking of a gate at an ascent position. SOLUTION: In this gate lifter in which a rod side chamber 3Lc of a first hydraulic cylinder 3L is connected with a drive source 41 through a first piping 42 and a counter-rod side chamber 3Ld is connected with a rod side chamber 3Rc of a second hydraulic cylinder 3R through a second piping 43 to lift and lower the gate along a support column by expanding, shrinking, and synchronizing the first and second hydraulic cylinders 3L, 3R, correction and sealing circuits 46, 47 for correcting deviation of mutual expansion amount by the hydraulic cylinders 3L, 3R when the first and second hydraulic cylinders 3L, 3R are shrunk and retracted and the gate is arranged at the ascent position and sealing pressure oil into the rod side chambers 3Lc, 3Rc and the first and second pipings 42, 43 by a predetermined pressure are provided. A buckling prevention means for preventing buckling of a piston rod 3Ld of the first hydraulic cylinder 3L is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder tuning apparatus for correcting a shift between a pair of left and right hydraulic cylinders for raising and lowering a gate of a gate lifter, and to a gate sunken prevention mechanism for preventing the gate from sinking at a gate ascending position. It is.

[0002]

2. Description of the Related Art In general, a gate at the rear end of a truck vehicle is raised and lowered by a gate lifter which supplies and discharges hydraulic oil from a hydraulic pump to a pair of cylinders to extend and contract a piston rod of each cylinder. . In such a gate lifter, the piston rods of each cylinder are attached to both left and right ends of the gate, so a cylinder tuning device that synchronizes the amount of expansion and contraction of the piston rod of each cylinder is required to keep the gate horizontal. It is considered indispensable.

As shown in FIG. 6, the cylinder tuning apparatus is configured such that a rod side chamber A1a of one cylinder A1 (left side in FIG. 6) is connected to a pump unit A2 by a first pipe A3.
And the other cylinder A4 (right side in FIG. 6) and the opposite rod side chamber A1b of one cylinder A1.
Is connected to the rod side chamber A4a through a second pipe A5,
It is conventionally known that check valves A6, A6 are provided in through holes A1d, A4d penetrating through the pistons A1c, A4c of the cylinders A1, A4 in the direction of expansion and contraction, respectively.

[0004] The pump unit A2 includes a motor A2a.
And the reservoir tank A2b are integrated,
A gear pump A2c is interposed between the two A2a and A2b. Then, the cylinder tuning apparatus A connects each check valve A6 to the opposite rod side chamber A1 of each cylinder A1, A4 at the upper limit position of the gate A7 substantially flush with the deck of the packing box.
The cylinders A1 and A4 are opened by contacting the end faces of the cylinders b and A4b to open the opposite rod-side chambers A1b and A4b of the cylinders A1 and A4 with the rod-side chambers A1a and A4a, respectively. Thereby, the oil amount of the non-rod side chambers A1b, A4b and the rod side chambers A1a, A4a of each cylinder A1, A4 is increased or decreased, and the piston rod A of each cylinder A1, A4 is increased.
The expansion and contraction amounts of 1e and A4e are synchronized.

[0005]

However, in the conventional cylinder tuning apparatus A, when the cylinders A1 and A4 are most contracted and the gate A7 is disposed substantially on the same plane as the floor of the carrier, the cylinder A1 and A4 are moved to the gate A7. When a load is applied downward by carrying a load, the cylinders A1, A4
In addition, a phenomenon in which the gate A sinks due to expansion of a pipe such as a hose serving as a hydraulic flow path has occurred. Therefore, if the gate sinks, for example, while the cargo is being transferred from the loading platform to the gate, it will hinder the movement of the cargo, and the gate may tilt and sink, causing the cargo to move unexpectedly, which is dangerous. There was a problem.

The present invention has been made in view of such a point, and if a predetermined sealing pressure is previously held in a cylinder or a pipe when a gate is raised, a load up to a load corresponding to the pressure is held. Focusing on the fact that the gate does not sink when placed on the gate, the cylinder of the gate lifter equipped with the gate sink prevention mechanism that prevents the gate from sinking by providing this function to the hydraulic circuit or cylinder structure It is an object to provide a tuning device.

[0007]

According to the first aspect of the present invention, there is provided a cylinder tuning apparatus for a gate lifter having a gate sunk prevention mechanism, comprising: a pressure receiving area on a side of a piston of a first hydraulic cylinder opposite a rod side chamber; and a second hydraulic cylinder. The piston has the same pressure receiving area as the side surface of the rod side chamber, the rod side chamber of the first hydraulic cylinder is connected to the drive source via the first pipe, and the opposite rod side chamber of the first hydraulic cylinder is connected to the second hydraulic cylinder. The second hydraulic cylinder is connected to the reservoir tank via a second pipe, and the opposite rod side chamber of the second hydraulic cylinder is connected to the reservoir tank via the third pipe. The working fluid is supplied and discharged from the drive source, and the piston rods of the respective cylinders are extended and contracted while being synchronized with each other. In the gate lifter that moves up and down along the pair of right and left columns, when the first and second hydraulic cylinders are retracted and the gate is disposed at the ascending position, the amount of mutual expansion and contraction by the first and second hydraulic cylinders is reduced. A correcting / sealing means for correcting the displacement and enclosing the pressurized oil at a predetermined pressure in each rod side chamber and the first and second pipes is provided, while the first hydraulic pressure is increased when the first and second hydraulic cylinders extend. A buckling prevention means is provided for preventing the pressure of the hydraulic oil from increasing on the side opposite to the rod side chamber of the cylinder to prevent buckling of the piston rod of the first hydraulic cylinder.

According to a second aspect of the present invention, in the gate lifter cylinder tuning apparatus provided with the gate sunk prevention mechanism, the correcting / enclosing means includes a check valve built in a piston of the first hydraulic cylinder and a check valve of the second pipe. A fourth pipe is connected to the middle part and the reservoir tank, and a solenoid valve and a relief valve of a two-position switching type are sequentially provided on the fourth pipe from the second pipe side. The fourth position is determined by a signal such as a position for closing the pipeline of the four pipes and an operation of an up switch for raising the gate.
The position can be switched to a position where the pipe of the pipe is opened.

According to the third aspect of the present invention, in the gate lifter cylinder tuning apparatus provided with the gate sunk prevention mechanism, the correcting / enclosing means is provided with a first correction provided between the first pipe and the second pipe. An enclosed circuit, and a second modified / enclosed circuit provided between the second pipe and the third pipe, wherein the first modified / enclosed circuit is located in the middle of the first pipe and in the middle of the second pipe. A fifth pipe is connected to the
A first solenoid valve of a two-position switching type and a first relief valve are sequentially provided in the pipe from the first pipe side, while a second correction / sealing circuit is provided downstream of the first relief valve. A sixth pipe is connected to a middle part of the fifth pipe and the middle part of the third pipe, and a second solenoid valve of a two-position switching type from the fifth pipe side to the sixth pipe, and a second relief valve. Are sequentially provided, and the first and second solenoid valves are arranged to close the conduits of the fifth and sixth pipes, and when the first and second hydraulic cylinders are most retracted,
The fifth and sixth pipes can be switched to open positions.

According to a fourth aspect of the present invention, in the gate lifter cylinder tuning apparatus provided with the gate sunk prevention mechanism, the correcting / enclosing means includes a check valve and a relief valve built in each piston of the first and second hydraulic cylinders. Each check valve is interposed in a communication passage that communicates between the rod side chamber and the opposite rod side chamber, and normally prevents the flow of pressure oil from the rod side chamber to the opposite rod side chamber, and the piston rod is most retracted. In this case, the first and second hydraulic cylinders come into contact with the push rods to allow the flow of the pressure oil from the rod side chamber to the opposite rod side chamber. To allow the flow of pressure oil from the rod side chamber to the opposite rod side chamber, while the relief valve is provided on the rod side chamber side of the communication passage, De-side chamber opens the communication passage if a predetermined pressure have been made from the anti-rod side chamber to prevent the flow of pressure oil to the rod side chamber.

[0011]

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

FIG. 1 shows the rear of a truck equipped with the gate lifter cylinder tuning apparatus of the present invention. The truck T has a packing box Tb at the rear of the vehicle body Ta. A gate lifter 1 is provided at the rear end of the packing box Tb. The gate lifter 1 is connected to the gate T of the track T.
By raising and lowering c in the vertical direction along the column 2 (described later), it is provided for facilitating the loading and unloading work of loading and unloading the unshown luggage into the packing box Tb.

The gate lifter 1 comprises a pair of right and left columns 2
(Only one is shown in FIG. 1) and a pair of first and second left and right
It includes hydraulic cylinders 3L, 3R and a cylinder tuning device.

Each of the columns 2 extends vertically upward from the deck surface Td at both left and right positions at the rear end of the packing box Tb. A slider 21 is provided in each of the columns 2 so as to be vertically movable along the column 2. At the lower end of each slider 21, a support bracket 22 projecting rearward from the column 2 is provided. The support bracket 22 has a base end portion of the gate Tc (FIG. 1).
The front end is supported rotatably about a horizontal axis (not shown). In this case, the gate Tc pivots around the horizontal axis with respect to each support bracket 22, so that the gate Tc stands upright along each column 2, and falls down substantially horizontally (position shown in FIG. 1). The posture is mutually changed.

Rollers 21a, 21a are rotatably supported on the upper end and the middle of each slider 21. The rollers 21a allow the slider 21 to slide smoothly in the up and down direction within the column 2. ing.

The first and second hydraulic cylinders 3L, 3R are:
Each of the columns 2 is provided so as to extend in the vertical direction substantially in parallel with each column 2. As shown in FIG. 2, each hydraulic cylinder 3L,
3R is composed of the upper and lower rod side chambers 3Lb and 3Rb and the lower rod side chambers 3Lc and 3R by the pistons 3La and 3Ra.
The front ends of the support brackets 22 are connected to distal ends (lower ends) of the piston rods 3Ld and 3Rd, respectively, which are defined below the pistons 3La and 3Ra.

In this case, the first hydraulic cylinder 3L and the second hydraulic cylinder 3R are connected to the side surface (the upper surface in FIG. 2) of the piston 3La of the first hydraulic cylinder 3L opposite the rod side chamber 3Lb.
Pressure receiving area and the piston 3Ra of the second hydraulic cylinder 3R
In order to match the pressure receiving area of the side surface of the rod side chamber 3Rc (the lower surface in FIG. 2), the rods are formed to have different diameters.

The gate Tc supplies the pressurized oil to the rod side chamber 3Lc of the first hydraulic cylinder 3L as will be described later, and the slider 21 via the support bracket 22 at the time of contraction to contract each of the piston rods 3Ld and 3Rd. Is raised, so that it is positioned at the upper limit position (the solid line position shown in FIG. 1) which is substantially flush with the deck surface Td of the packing box Tb. On the other hand, the gate Tc discharges pressurized oil from the rod side chamber 3Lc of the first hydraulic cylinder 3L and lowers the slider 21 via the support bracket 22 when the piston rods 3Ld and 3Rd are extended to extend to the ground G. It is positioned at a descending position where it touches the ground (a position indicated by a two-dot chain line in FIG. 1).

FIG. 2 shows a hydraulic circuit for operating the cylinder tuning device of the gate lifter.

The cylinder tuning device corrects the displacement of the piston rods 3Ld, 3Rd of the left and right hydraulic cylinders 3L, 3R when the displacement has occurred, and synchronizes the displacement of the piston rods 3Ld, 3Rd. The pump unit 41 includes a pump unit 41 as a drive source, first to third pipes 42 to 44, a check valve 47 and a correction / sealing circuit 46 constituting a correction / sealing means.

The pump unit 41 includes a gear pump 41b driven by a motor 41a, a control valve 41c for controlling the elevation of the gate Tc, and a reservoir tank 41d as main parts.

The gear pump 41b has a suction port connected to a reservoir tank 41d through a suction pipe 41e, and one end of the first pipe 42 connected to a discharge port.

The control valve 41c is a two-position switching type solenoid valve that can be switched between an upper position and a lower position in FIG. 2 by exciting and demagnetizing the solenoid SOL1 by operating a gate lift switch (not shown). It is interposed in a discharge pipe 41f that communicates with the middle part and the reservoir tank 41d.

Further, a flow regulating valve 41h is interposed in the discharge pipe 41f closer to the reservoir tank 41d than the control valve 41c. The flow rate adjusting valve 41h adjusts the flow rate of the pressure oil flowing from the first pipe 42 to the reservoir tank 41d to a predetermined amount, so that the descending speed of the gate Tc becomes constant.

The first pipe 42 has one end connected to the discharge port of the gear pump 41b as described above, and the other end connected to the rod side chamber 3Lc of the first hydraulic cylinder 3L. The first gear pump 41b is closer to the gear pump 41b than the communicating portion of the discharge pipe 41f.
A check valve 41i is interposed in the pipe 42.
i prevents the backflow of the pressure oil to the gear pump 41d side.

The second pipe 43 has one end connected to the opposite rod side chamber 3Lb of the first hydraulic cylinder 3L and the other end connected to the rod side chamber 3Rc of the second hydraulic cylinder 3R.

The third pipe 44 has one end connected to the opposite rod side chamber 3Rb of the second hydraulic cylinder 3R and the other end connected to the reservoir tank 41d.

A fourth part is provided in the middle of the second pipe 43.
One end of the pipe 45 is connected, and the other end of the fourth pipe 4 is connected to the reservoir tank 41d. And this 4th
The pipe 45 has a correction / sealing circuit 4 which is a main part of the present invention.
6 are interposed.

The correcting / enclosing circuit 46 comprises a two-position switching type solenoid valve 46a, and a relief valve 46b provided in series on the reservoir tank 41d side with respect to the solenoid valve 46a.

The solenoid valve 46a is connected to the fourth pipe 45
2 and a right position to open the pipeline of the fourth pipe 45, and is normally arranged at the left position, and is operated by operating an up switch for raising the gate. The position is switched to the right position by exciting the solenoid SOL2.

The relief valve 46b opens the line of the fourth pipe 45 when the pressure on the upstream side of the fourth pipe 45 becomes higher than a predetermined set pressure. This set pressure is provided to the pump unit 41. The pressure is set to be smaller than the set pressure of the relief valve 41j.

The correction / sealing circuit 46 also has a pressure oil sealing function for sealing pressure oil into the first and second hydraulic cylinders. The pressure oil filling function will be described later in detail.

On the other hand, a check valve 47 is provided on the piston 3La of the first hydraulic cylinder 3L.
The check valve 47 is interposed in a communication passage 48 that connects the rod side chamber 3Lc and the non-rod side chamber 3Lb, and normally prevents the flow of pressure oil from the rod side chamber 3Lc to the non-rod side chamber 3Lb, When 3Ld is most retracted, it comes into contact with the push rod 49 provided in the first hydraulic cylinder 3L to allow the flow of the pressure oil from the rod side chamber 3Lc to the opposite rod side chamber 3Lb, and the opposite rod side chamber 3Lb has a predetermined pressure. When the pressure exceeds the pressure, the communication passage 48 is opened to allow the flow of the pressure oil from the non-rod side chamber 3Lb to the rod side chamber 3Lc.

Next, the gate lifting / lowering operation performed by the gate lifter cylinder tuning device configured as described above, and when the gate is tilted to the left or right from a horizontal state, the gate is adjusted by adjusting the tilt. A description will be given of a tuning operation for bringing the camera into a horizontal state.

First, when the control valve 41c is switched to the up position by the gate up / down switch while the gate Tc is at the down position, the gear pump 41b is driven by the motor 41a to supply pressure oil to the first pipe 42. Thereby, pressure oil is supplied to the rod side chamber 3Lc of the first hydraulic cylinder 3L, and the piston rod 3Ld of the first hydraulic cylinder 3L contracts. At the same time, pressure oil proportional to the pressure oil supplied to the rod side chamber 3Lc of the first hydraulic cylinder 3L is supplied from the opposite rod side chamber 3Lb of the first hydraulic cylinder 3L to the second pipe 43.
Is supplied to the rod-side chamber 3Rc of the second hydraulic cylinder 3R, and the pressure receiving areas are made to coincide with each other as described above, so that the piston rod 3Rd of the second hydraulic cylinder 3R contracts by the same length as the piston rod 3Ld. In this way, the left and right first and second hydraulic cylinders 3L, 3R are synchronized, so that the gate Tc ascends to the ascending position while maintaining the horizontal position.

On the other hand, the control valve 4 is controlled by a gate lift switch.
When 1c is switched to the lowered position, the pressure oil is returned from the rod side chamber 3Lc of the first hydraulic cylinder 3L to the reservoir tank 41d through the first pipe 42 and the discharge pipe 41f by the weight of the gate Tc. Thereby, the first hydraulic cylinder 3L
The piston rod 3Ld extends. At the same time as the first
In the opposite rod side chamber 3Lb of the hydraulic cylinder 3L, the same amount of pressure oil as the pressure oil returned from the rod side chamber 3Lc of the first hydraulic cylinder 3L is supplied to the rod side chamber 3Rc of the second hydraulic cylinder 3R.
Through the second pipe 43, the piston rod 3Rd of the second hydraulic cylinder 3R extends the same length as the piston rod 3Ld. In this way, the left and right first and second hydraulic cylinders 3L and 3R are synchronized, and the gate Tc descends to the descending position while maintaining the horizontal position.

Next, the gate Tc which moves up and down as described above
Is tilted to the left or right due to pressure oil leakage from the rod side chamber 3Lc of the first hydraulic cylinder 3L to the opposite rod side chamber 3Lb, for example, the left and right first and second hydraulic cylinders 3L, Gate Tc by adjusting the amount of expansion and contraction of 3R piston rods 3Ld and 3Rd
The procedure for correcting the horizontal position will be described.

First, in the case where the first hydraulic cylinder 3L (left side) is displaced in the downward direction and the left side of the gate Tc is inclined downward, as described above, the first hydraulic cylinder 3L and the second hydraulic cylinder 3R is degenerated and gate Tc
Is raised to the raised position, first, the second hydraulic cylinder 3R completes the contraction first. At this time, the solenoid valve 46a is switched to the right position in conjunction with the operation of the up switch. When pressure oil is further supplied to the rod-side chamber 3Lc of the first hydraulic cylinder 3L in this state, the pressure in the rod-side chamber 3Lb and the pressure in the second pipe 43 also increase with the increase in the pressure in the rod-side chamber 3Lc. Therefore, when this pressure becomes higher than the set pressure of the relief valve 46b, the relief valve 46b is opened, and by opening of the relief valve 46b, the non-rod side chamber 3Lb of the first hydraulic cylinder 3L is opened.
Is returned to the reservoir tank 41d through the second pipe 43 and the fourth pipe 45. As a result, the first hydraulic cylinder 3L is most contracted, the displacement of the first hydraulic cylinder 3L is corrected, and the gate Tc is in the horizontal state.

When the displacement of the first hydraulic cylinder 3L is corrected in this manner, by turning off the lift switch,
The solenoid valve 46a switches to the left position to close the fourth pipe 45.

At this time, the first and second hydraulic cylinders 3L, 3L
The pressure corresponding to the set pressure of the relief valve 46b is sealed in the R, the first pipe 42, and the second pipe 43. Therefore, even if a load is placed on the gate Tc when the gate Tc is at the ascending position, the gate Tc can be prevented from sinking for a load corresponding to the pressure, and the load can be safely gated. It can be loaded and unloaded on Tc.

On the other hand, when the right side of the gate Tc is tilted downward due to a downward displacement on the second hydraulic cylinder 3R side (right side), the first hydraulic cylinder 3L and the second hydraulic cylinder 3R is degenerated and gate Tc
Is raised to the raised position, first, the first hydraulic cylinder 3L completes contraction first. At this time, the solenoid valve 46a is switched to the right position in conjunction with the operation of the ascent switch or the detection of another retracted position detection sensor or the like. When pressure oil is further supplied to the rod side chamber 3Lc of the first hydraulic cylinder 3L in this state, the check valve 47 abuts on the push rod 49 to allow the flow of the pressure oil from the rod side chamber 3Lc to the opposite rod side chamber 3Lb. For,
The pressure oil flows through the second pipe 43 to the second hydraulic cylinder 3R.
Is supplied to the rod side chamber 3Rc. As a result, the second hydraulic cylinder 3R contracts most and the second hydraulic cylinder 3R
Is corrected, and the gate Tc becomes horizontal. The rod side chamber 3Rc of the second hydraulic cylinder 3R and the second
When the pressure in the pipe 43 becomes higher than the set pressure of the relief valve 46b, the relief valve 46b is opened, and the pressure oil supplied to the second pipe 43 is returned to the reservoir tank 41d through the fourth pipe 45.

At this time, the first and second hydraulic cylinders 3L, 3L
The pressure corresponding to the set pressure of the relief valve 46b is sealed in the R, the first pipe 42, and the second pipe 43. Therefore, even if a load is placed on the gate Tc when the gate Tc is at the ascending position, the gate Tc can be prevented from sinking for a load corresponding to the pressure, and the load can be safely gated. It can be loaded and unloaded on Tc.

That is, in addition to the function of correcting the displacement between the first hydraulic cylinder 3L and the second hydraulic cylinder 3R, the correcting / enclosing circuit 46 also supplies the first and second hydraulic cylinders 3L with a predetermined pressure at a predetermined pressure. , 3R and the first and second pipes 42 and 43 are also provided with a pressure oil sealing function.

When the gate Tc is lowered as described above, if any obstacle contacts the left side of the gate Tc and the lowering of the left side of the gate Tc is prevented, the second hydraulic cylinder 3R The pressure oil in the rod-side chamber 3Rc flows through the second pipe 43 to the counter-rod-side chamber 3Lc of the first hydraulic cylinder 3L and presses the piston 3La downward, so that the piston rod 3Ld extends despite the presence of an obstacle. Act on. Thus, the piston rod 3Ld
When the force for extending the pressure is continuously applied, the buckling occurs in the piston rod 3Ld which is prevented from being extended. However, in this example, when the pressure on the non-rod side chamber 3Lb becomes equal to or higher than a predetermined pressure, the communication passage 48 is opened by the check valve 47 to allow the flow of the pressure oil from the non-rod side chamber 3Lb to the rod side chamber 3Lc. Can be prevented from being applied with an excessive load, whereby the buckling can be prevented.

That is, when the gate Tc is lowered by extending the first and second hydraulic cylinders 3L and 3R, the check valve 47 supplies the pressure oil on the side opposite to the rod side chamber 3Lc of the first hydraulic cylinder 3L. The first hydraulic cylinder 3L has a function as a buckling preventing means for preventing buckling of the piston rod 3Ld of the first hydraulic cylinder 3L by preventing a rise in pressure.

FIG. 3 shows another embodiment of the hydraulic circuit. The same components as those of the above-described hydraulic circuit are denoted by the same reference numerals, and description thereof will be omitted.

In this hydraulic circuit, a first correction / sealing circuit 50 is provided between the first pipe 42 and the second pipe 43, and a second correction / sealing is provided between the second pipe 43 and the third pipe 44. A circuit 51 is provided.

The first correcting / enclosing circuit 50 includes a first pipe 42
A two-position switching type first solenoid valve 50a provided in a fifth pipe 52 connected between a middle part of the second pipe 43 and a middle part of the second pipe 43, and the first solenoid valve 50a
And a first relief valve 50b provided in the fifth pipe 52 on the downstream side of the first.

The first solenoid valve 50a is connected to the lower position in FIG.
The first hydraulic cylinder 3L is most retracted and the solenoid SOL3 is energized when the limit switch LS1 is turned on when the first hydraulic cylinder 3L is most retracted. By doing so, it is switched to the upper position.

The second correction / sealing circuit 51 includes a sixth pipe 53 connected between a middle part of the fifth pipe 52 downstream of the first relief valve 50b and a middle part of the third pipe 44. And a second relief valve 51b provided in the sixth pipe 53 downstream of the second solenoid valve 51a.

The second solenoid valve 51a closes the line of the sixth pipe 53 in FIG.
3 can be switched to an upper position to open the pipeline, and is normally arranged at a lower position. When the second hydraulic cylinder 3R is most retracted and the limit switch LS2 is turned on, the solenoid SOL4 is excited. By doing so, it is switched to the upper position.

The fifth pipe 52 is connected to a bypass pipe 54 for bypassing the first correction / sealing circuit 50. The bypass pipe 54 is connected to a check valve 55.
Is provided. This check valve 55 prevents the flow of the pressure oil from the first pipe 42 side to the second pipe 43 side,
The flow of the pressure oil from the second pipe 43 to the first pipe 42 is allowed.

As described above, the first correction / sealing circuit 50 and the second
By providing the correction / enclosure circuit 51, for example, in a case where a downward displacement occurs on the first hydraulic cylinder 3L side (left side) and the left side of the gate Tc is inclined downward, as described above, the first hydraulic pressure is applied. Cylinder 3L and second hydraulic cylinder 3
When the gate Tc is raised to the raised position by reducing R, first, the second hydraulic cylinder 3R completes the reduction first. As a result, the limit switch LS2 is turned on, so that the second solenoid valve 51a is switched to the upper position.

In this state, when pressure oil is further supplied to the rod side chamber 3Lc of the first hydraulic cylinder 3L, the pressure in the rod side chamber 3Lb and the pressure in the second pipe 43 also increase as the pressure in the rod side chamber 3Lc increases. . Therefore, when this pressure becomes higher than the set pressure of the second relief valve 51b, the second relief valve 51b is opened, and the oil in the non-rod side chamber 3Lb of the first hydraulic cylinder 3L is released by the opening of the second relief valve 51b. Third pipe 4 through pipe 53
4 and returned to the reservoir tank 41d. As a result, the first hydraulic cylinder 3L is most contracted, the displacement of the first hydraulic cylinder 3L is corrected, and the gate Tc is in the horizontal state.

When the displacement of the first hydraulic cylinder 3L is corrected in this way, the limit switch LS1 is also turned on, and the first solenoid valve 50a is switched to the upper position, so that the first and second hydraulic cylinders 3L, 3R In addition, the pressures corresponding to the set pressures of the first and second relief valves 50b and 51b are filled in the first pipe 42 and the second pipe 43, respectively, so that the appropriate filling pressure is secured even when the raising operation is stopped. It will be in the state that was done. Therefore, even if a load is placed on the gate Tc when the gate Tc is in the ascending position, the gate Tc is not affected by a load corresponding to the above pressure.
Of cargo can be prevented, and cargo can be safely transferred to the gate T
c and can be unloaded.

On the other hand, when the right side of the gate Tc is inclined downward due to the downward displacement of the second hydraulic cylinder 3R side, the first hydraulic cylinder 3L and the second hydraulic cylinder 3R are retracted as described above. Then, when the gate Tc is raised to the raised position, first, the first hydraulic cylinder 3L completes contraction first. Thereby, the limit switch LS1
Is turned ON, the first solenoid valve 50a is switched to the upper position.

In this state, when pressure oil is further supplied to the rod-side chamber 3Lc of the first hydraulic cylinder 3L, the pressure in the rod-side chamber 3Lc and the fifth pipe 52 increases, and this pressure is set to the first relief valve 50b. When the pressure becomes higher than the pressure, the first relief valve 50b is opened, and when the first relief valve 50b is opened, the pressure oil flows through the fifth pipe 52 to the rod side chamber 3Rc of the second hydraulic cylinder 3R. As a result, the second hydraulic cylinder 3R is most contracted, the displacement of the second hydraulic cylinder 3R is corrected, and the gate Tc is in the horizontal state.

When the displacement of the second hydraulic cylinder 3R is corrected in this way, the limit switch LS2 is also turned on, and the second solenoid valve 51a is switched to the upper position, so that the first and second hydraulic cylinders 3L, 3R , And the pressures corresponding to the set pressures of the first and second relief valves 50b and 51b are filled in the first pipe 42 and the second pipe 43, respectively. Enclosure pressure will be secured. Therefore, even if a load is placed on the gate Tc when the gate Tc is at the ascending position, the gate Tc can be prevented from sinking for a load corresponding to the pressure, and the load can be safely gated. It can be loaded and unloaded on Tc.

That is, the first and second correction / sealing circuits 50,
51 is a first hydraulic cylinder 3L and a second hydraulic cylinder 3R
The first and second hydraulic cylinders 3L, 3R and the first and second pipes 4
It also has a pressure oil sealing function for sealing into 2, 43.

When the gate Tc is lowered as described above, and an obstacle contacts the left side of the gate Tc to prevent the left side of the gate Tc from lowering, the second hydraulic cylinder Since the pressure oil of the rod side chamber 3Rc of the 3R flows to the first pipe 42 through the check valve 55 of the bypass pipe 54, it is possible to prevent an excessive load from acting on the piston rod 3Ld of the first hydraulic cylinder 3L.
Buckling of the piston rod 3Ld can be prevented from occurring as in the case described above.

That is, when the gate Tc is lowered by extending the first and second hydraulic cylinders 3L and 3R, the check valve 55 transmits the pressure oil on the side opposite to the rod side chamber 3Lc of the first hydraulic cylinder 3L. The first hydraulic cylinder 3L has a function as a buckling preventing means for preventing buckling of the piston rod 3Ld of the first hydraulic cylinder 3L by preventing a rise in pressure.

FIG. 4 shows a function for correcting the above-mentioned displacement between the first hydraulic cylinder 3L and the second hydraulic cylinder 3R, and a method for displacing the pressure oil at a predetermined pressure with the first and second hydraulic cylinders 3L and 3R and the first and second hydraulic cylinders 3L and 3R. A circuit in which the pressure oil sealing function sealed in the second pipes 42 and 43 is structurally incorporated in the piston is shown. Note that the same components as those of the above-described hydraulic circuits are denoted by the same reference numerals, and description thereof is omitted.

Each piston of the first and second hydraulic cylinders 3L and 3R has a built-in check valve 47 and relief valve 60, respectively.

More specifically, as shown in FIG. 5, each check valve 47 is interposed in a communication passage 48 that communicates between the rod side chambers 3Lc and 3Rc and the opposite rod side chambers 3Lb and 3Rb. The flow of pressure oil from the side chambers 3Lc, 3Rc to the non-rod side chambers 3Lb, 3Rb is prevented, and when the piston rods 3Ld, 3Rd are retracted most, they come into contact with the push rods 49 provided on the first hydraulic cylinders 3L, 3R. To allow the flow of pressure oil from the rod side chambers 3Lc, 3Rc to the non-rod side chambers 3Lb, 3Rb,
When the pressure on the non-rod side chambers 3Lb, 3Rb becomes equal to or higher than a predetermined pressure, the communication passage 48 is opened to allow the flow of the pressure oil from the non-rod side chambers 3Lb, 3Rb to the rod side chambers 3Lc, 3Rc.

As shown in FIG. 5, the relief valve 60 is provided on the rod side chamber 3Lc, 3Rc side of the communication path 48, and opens the communication path 48 when the rod side chambers 3Lc, 3Rc reach a predetermined pressure. The flow of the pressure oil from the side chambers 3Lc and 3Rc to the opposite rod side chambers 3Lb and 3Rb is allowed.

As shown in FIG. 4, a check valve 62 is provided in the communication pipe 61 which connects the first pipe 42 and the second pipe 43, and the first pipe 42 is connected to the second pipe 4.
3 and the flow of the pressure oil from the second pipe 43 to the first pipe 42 is allowed.

By providing the check valve 47 and the relief valve 60 on each of the pistons 3La and 3Ra in this manner, for example, a shift in the descending direction occurs on the first hydraulic cylinder 3L side (left side), and the left side of the gate Tc is lowered. When the first hydraulic cylinder 3L and the second hydraulic cylinder 3R are retracted to raise the gate Tc to the raised position as described above, first, the second hydraulic cylinder 3R completes the retracting first. . At this time, the check valve 47 of the second hydraulic cylinder 3R comes into contact with the push rod 49 to allow the flow of the pressure oil from the rod side chamber 3Rc to the opposite rod side chamber 3Rb.

In this state, when pressure oil is further supplied to the rod side chamber 3Lc of the first hydraulic cylinder 3L, the second pipe 43 and the rod side chamber 3Rc of the second hydraulic cylinder 3R are increased as the pressure in the rod side chamber 3Lc increases. Pressure also increases,
This pressure is applied to the relief valve 60 of the second hydraulic cylinder 3R.
When the pressure becomes higher than the set pressure, the relief valve 60 opens, and by the opening of the relief valve 60, the pressure oil in the rod side chamber 3Rc of the second hydraulic cylinder 3R flows through the communication passage 48 to the third pipe 44 and is returned to the reservoir tank 41d. You. As a result, the first hydraulic cylinder 3L is most contracted, the displacement of the first hydraulic cylinder 3L is corrected, and the gate Tc is in the horizontal state. Further, when pressure oil is supplied, the relief valve 60 of the piston 3La of the first hydraulic cylinder 3L is opened.

At this time, the first and second hydraulic cylinders 3L, 3L
The pressure corresponding to the set pressure of the relief valves 60, 60 is filled in the R, the first pipe 42, and the second pipe 43, respectively. Therefore, even if a load is placed on the gate Tc when the gate Tc is in the ascending position, the gate Tc is not affected by a load corresponding to the pressure.
c can be prevented from sinking, and the cargo can be safely loaded and unloaded on the gate Tc.

On the other hand, if the right side of the gate Tc is tilted downward due to a downward displacement on the second hydraulic cylinder 3R side, the first hydraulic cylinder 3L and the second hydraulic cylinder 3R are retracted as described above. Then, when the gate Tc is raised to the raised position, first, the first hydraulic cylinder 3L completes contraction first. At this time, the check valve 47 of the first hydraulic cylinder 3L comes into contact with the push rod 49 to allow the flow of the pressure oil from the rod side chamber 3Lc to the opposite rod side chamber 3Lb.

In this state, when pressure oil is further supplied to the rod side chamber 3Lc of the first hydraulic cylinder 3L, the pressure in the rod side chamber 3Lc rises, and this pressure becomes higher than the set pressure of the relief valve 60 of the first hydraulic cylinder 3L. When the pressure rises, the relief valve 60 is opened, and by the opening of the relief valve 60, the pressure oil in the rod side chamber 3Lc of the first hydraulic cylinder 3L flows through the communication path 48 and the second pipe 43 to the rod side chamber 3Rc of the second hydraulic cylinder 3R. . This allows the second
The hydraulic cylinder 3R is retracted upward and the displacement is corrected. Further, when the pressurized oil is supplied, the pressure rises and the opposite rod side chamber 3
Rb pressure oil is supplied to the reservoir tank 41 through the third pipe 44.
Returned to d. As a result, the second hydraulic cylinder 3R is most contracted, the displacement of the second hydraulic cylinder 3R is corrected, and the gate Tc is in a horizontal state.

At this time, the first and second hydraulic cylinders 3L, 3L
The pressure corresponding to the set pressure of the relief valves 60, 60 is filled in the R, the first pipe 42, and the second pipe 43, respectively. Therefore, even if a load is placed on the gate Tc when the gate Tc is in the ascending position, the gate Tc is not affected by a load corresponding to the pressure.
c can be prevented from sinking, and the cargo can be safely loaded and unloaded on the gate Tc.

When the gate Tc is lowered as described above, and an obstacle contacts the left side of the gate Tc to prevent the left side of the gate Tc from lowering, the second hydraulic cylinder The pressure oil of the rod side chamber 3Rc of the 3R is supplied to the first pipe 42 through the check valve 62 of the communication pipe 61.
Since it flows to the side, an excessive load can be prevented from acting on the piston rod 3Ld of the first hydraulic cylinder 3L, and buckling of the piston rod 3Ld can be prevented in the same manner as described above.

That is, when the gate Tc is lowered by extending the first and second hydraulic cylinders 3L and 3R, the check valve 62 controls the pressure oil on the side of the first hydraulic cylinder 3L opposite the rod side chamber 3Lc. The first hydraulic cylinder 3L has a function as a buckling preventing means for preventing buckling of the piston rod 3Ld of the first hydraulic cylinder 3L by preventing a rise in pressure.

[0075]

As described above, according to the gate lifter cylinder tuning apparatus of the present invention, when the gate is arranged at the raised position by the correcting / enclosing means of the cylinder tuning apparatus,
A load was placed on the gate at the ascending position by automatically correcting the displacement of the expansion and contraction amounts of the left and right hydraulic cylinders, and filling the rod side chamber, the first and second pipes with pressurized oil at a predetermined pressure. As a result, it is possible to prevent the gate from sinking for a load corresponding to the sealed pressure,
This allows the cargo to be safely loaded and unloaded on the gate.

[Brief description of the drawings]

FIG. 1 is a sectional view of the vicinity of a rear portion of a track provided with a gate lifter cylinder tuning device of the present invention.

FIG. 2 is a hydraulic circuit of the cylinder tuning device.

FIG. 3 is a circuit diagram showing another configuration of the hydraulic circuit of the cylinder tuning device.

FIG. 4 is a circuit diagram showing still another configuration of the hydraulic circuit of the cylinder tuning device.

FIG. 5 is a sectional view showing a specific structure of a piston.

FIG. 6 is a hydraulic piping system diagram of a cylinder tuning device according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gate lifter 2 Prop 3L 1st hydraulic cylinder 3Lb Non-rod side chamber 3Lc Rod side chamber 3Ld Piston rod 3R 2nd hydraulic cylinder 3Rc Rod side chamber 3Rd Piston rod 41d Reservoir tank 42 1st piping 43 2nd piping 44 3rd piping 45 4th piping 46 Correction and sealing circuit (correction and sealing means) 46a Solenoid valve 46b Relief valve 47 Check valve 50 First correction and sealing circuit 50a First solenoid valve 50b First relief valve 51 Second correction and sealing circuit 51a Second solenoid valve 51b First 2 Relief valve 52 Fifth pipe 53 Sixth pipe 55 Check valve 60 Relief valve 62 Check valve

Claims (4)

[Claims] The pressure receiving area on the side of the piston of the first hydraulic cylinder opposite to the rod side is equal to the pressure receiving area of the side of the rod side chamber of the piston of the second hydraulic cylinder, and the rod side chamber of the first hydraulic cylinder is driven by the drive source. Is connected to the rod side chamber of the first hydraulic cylinder via a second pipe, and the opposite rod side chamber of the second hydraulic cylinder is connected to the atmosphere. Open or connected to a reservoir tank via a third pipe, the hydraulic fluid is supplied and discharged from the drive source to the first hydraulic cylinder, and the piston rod of each cylinder is expanded and contracted while being tuned. A gate lifter for raising and lowering a gate connected to a piston rod along a pair of right and left columns, wherein the first and second hydraulic cylinders are retracted. When placing the gate in the raised position, thereby correcting the deviation of the mutual expansion and contraction amount of the first hydraulic cylinder and second hydraulic cylinder,
A correction / sealing means for sealing the pressure oil at a predetermined pressure is provided in each rod side chamber and the first and second pipes.
And a buckling preventing means for preventing a pressure oil pressure increase on the side opposite to the rod side chamber of the first hydraulic cylinder during extension operation of the second hydraulic cylinder to prevent buckling of the piston rod of the first hydraulic cylinder. A gate lifter cylinder tuning device provided with a gate sinking prevention mechanism. 2. The correction / enclosing means includes: a check valve built in a piston of a first hydraulic cylinder;
A fourth pipe is connected to a middle part of the pipe and the reservoir tank, and a solenoid valve and a relief valve of a two-position switching type are sequentially provided on the fourth pipe from the second pipe side. 2. The apparatus according to claim 1, wherein a position of closing the pipe of the fourth pipe and a position of opening the pipe of the fourth pipe by a signal such as an operation of an up switch for raising the gate. Gate lifter cylinder tuning device equipped with a gate sinking prevention mechanism. 3. The correction / sealing means is provided between a first correction / sealing circuit provided between the first pipe and the second pipe, and between the second pipe and the third pipe. The second
The first correction / sealing circuit includes a fifth pipe connected to a middle part of the first pipe and a middle part of the second pipe, and the fifth pipe is connected to the fifth pipe from the first pipe side. A two-position switching type first solenoid valve and a first relief valve are sequentially provided. On the other hand, the second correction / sealing circuit is provided in the middle of a fifth pipe downstream of the first relief valve and the first relief valve. A sixth pipe is connected to an intermediate part of the third pipe, and a second solenoid valve of a two-position switching type and a second relief valve are sequentially provided on the sixth pipe from the fifth pipe side. The second solenoid valve is set between a position where the pipes of the fifth and sixth pipes are closed and a position where the pipes of the fifth and sixth pipes are opened when the first and second hydraulic cylinders are most retracted. 2. The gate according to claim 1, wherein the gate is switchable. Cylinder tuning device Getorifuta having only prevention mechanism. 4. The correcting / enclosing means comprises a check valve and a relief valve built in each piston of the first and second hydraulic cylinders, and each check valve communicates between the rod side chamber and the opposite rod side chamber. It is interposed in the communication passage and normally prevents the flow of pressure oil from the rod side chamber to the opposite rod side chamber, and when the piston rod is retracted most, it comes into contact with the push rods provided in the first and second hydraulic cylinders. To allow the flow of pressure oil from the rod side chamber to the opposite rod side chamber, and, when the opposite rod side chamber has a predetermined pressure or more, open the communication passage to allow the flow of pressure oil from the rod side chamber to the opposite rod side chamber. On the other hand, the relief valve is provided on the rod side chamber side of the communication path, opens the communication path when the rod side chamber reaches a predetermined pressure, and releases the pressure oil from the opposite rod side chamber to the rod side chamber. Cylinder tuning device Getorifuta having a gate sink preventing mechanism according to claim 1, characterized in that adapted to prevent les.