JPH0112961B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) This invention controls the rising speed of a cylinder, and controls the cylinder to operate quickly when the load is small and slowly when the load is large. Regarding equipment.

(Prior art) Figure 3 is related to U.S. Patent No. 3071926.
In this device, when the control valve 50 is switched from the illustrated neutral position to the right in the drawing, oil discharged from the pump 51 is supplied to the piston side chamber 54 of the cylinder 53 via the check valve 52.

At this time, if the load pressure of the cylinder 53 is equal to or lower than the set pressure of the sequence valve 55, the sequence valve 55 remains closed, so that the hydraulic fluid discharged from the rod side chamber 56 of the cylinder 53 passes through the check valve 57. and is returned to the piston side chamber 54.

When the load pressure of the cylinder 53 is low as described above, the return oil from the rod side chamber 56 is also supplied to the piston side chamber 54 except for the discharge amount of the pump 51, so that the operating speed becomes faster.

When the load pressure of the cylinder 53 becomes equal to or higher than the set pressure, the sequence valve 55 opens and the hydraulic oil in the rod side chamber 56 is returned to the tank 58.

Therefore, when the load pressure of the cylinder 53 exceeds the set pressure, the flow rate supplied to the cylinder 53 is only the pump discharge amount, and the operating speed is slowed by the amount of oil discharged from the rod side chamber 56 that is not supplied.

(Problems to be Solved by the Present Invention) In the conventional device as described above, the cylinder 5
Every time the load pressure in step 3 changes beyond the set pressure,
Since the sequence valve 55 opens and closes,
There was a problem that the operating speed of the cylinder 53 changed each time, and the cylinder did not rise smoothly.

An object of the present invention is to provide a device in which the operating speed of a cylinder does not change even if the load pressure of the cylinder repeatedly changes beyond a set pressure.

(Means for solving the problem) This invention is arranged between a pump and a cylinder,
It is equipped with a control valve that controls the switching operation of supplying and discharging pressure oil to the cylinder, and when the load pressure of the cylinder is below the set pressure, the communication between the rod side chamber and the tank is cut off, and when the load pressure is above the set pressure. A sequence valve mechanism is provided which switches the rod side chamber to communicate with the tank when the rod side chamber reaches the piston side chamber, and allows only flow from the rod side chamber to the piston side chamber. This assumes a cylinder control device equipped with a check valve.

Based on the above device, the present invention forms a sequence valve chamber in the spool of the control valve to which oil discharged from the pump is supplied when the spool is switched in one direction, and this valve chamber. is equipped with a main valve that forms an orifice and a poppet that opens when the pressure exceeds a set pressure, while simultaneously communicating the rod side chamber of the cylinder with the tank when the poppet opens and the main valve moves to a predetermined position. The present invention is characterized in that the control hole formed in the main valve is communicated with the through hole of the spool, and the back pressure chamber of the main valve is communicated with the tank.

(Operation of the present invention) Since the present invention is constructed as described above, the poppet remains closed as long as the load pressure of the cylinder is equal to or lower than the set pressure. In this state, load pressure acts on the back pressure chamber of the main valve, so the main valve maintains its original position and blocks the flow path that communicates the rod side chamber of the cylinder with the tank.

If the flow path that communicates the rod side chamber with the tank is shut off in this way, the oil discharged from the rod side chamber will be supplied to the piston side chamber of the cylinder via the check valve, which will increase the operating speed of the cylinder. Become.

Further, when the load pressure of the cylinder exceeds the set pressure, the poppet opens to communicate the back pressure chamber with the tank. To do this, the main valve moves and opens a flow path that communicates the rod side chamber with the tank. If the rod side chamber and the tank communicate in this manner, the discharged oil from the rod side chamber is returned to the tank, so that only the discharge amount of the pump is supplied to the cylinder. Therefore, the operating speed of the cylinder is also slowed down to the extent that the discharged oil from the rod side chamber is not supplied.

Also, once the back pressure chamber communicates with the tank,
Even if the cylinder load pressure falls below the set pressure and the poppet closes, the main valve maintains its moving position, so the communication between the rod side chamber and the tank remains cut off.

(Effects of the Present Invention) According to the control device of the present invention, when the load pressure of the cylinder exceeds the set pressure and the main valve moves, the operating speed of the cylinder changes even if the load pressure subsequently decreases. The operation of the cylinder becomes stable.

(Embodiment of the present invention) A spool 2 is slidably installed inside the valve body 1, and the spool 2 is normally held at the neutral position shown in FIG. 1 by the action of a spring 3.

When the spool 2 is in the neutral position as described above, the communication hole 4 in the valve body 1 is maintained in an open state. When the communication hole 4 is open in this manner, the pump port 5 communicates with the first tank port 6. Therefore, the pressure oil from pump 7 is directly transferred to tank 8.
return to.

Now, when the spool 2 is pulled in the right direction in FIG. 1 against the spring 3, the communication hole 4 is completely blocked by the spool 2. When the communication hole 4 is blocked, pressure oil from the pump 7 pushes open the check valve 9 and flows into the passage 10.

At this time, since the spool 2 communicates the passage 10 and the main port 12 through the annular groove 11, the pressure oil from the pump 7 flows into the piston side chamber 29 of the cylinder 28 through the pipe 13. , let it rise.

On the other hand, the spool 2 has an oil passage hole 14 formed in its diameter direction. The oil passage hole 14 is closed when the spool 2 is in the neutral position, and communicates with the pump port 5 when the spool 2 is moved rightward in FIG. Furthermore, this oil passage hole 14 communicates with the sequence valve chamber 16 of the spool 2 via a passage hole 15 formed along the axis of the spool 2.

The main valve 17 is located in the sequence valve chamber 16.
and poppet 18 are incorporated. The main valve 17 is formed with an orifice 19, and the through hole 15 side and the poppet 1 are connected through this orifice.
It communicates with the 8th side. Also, this main valve 17 is normally in the position shown in FIG. 1 due to the action of a spring 20. That is, the communication between the communication hole 21 formed in the spool 2 and the discharge hole 22 is cut off, and the control hole 23 formed in the main valve 17 and the through hole 24 formed in the spool 2 are made to be different from each other.
It is held in a relative position that closes the through hole 24.

However, the main valve 17 is connected to the spring 2.
0, the communication hole 21 and the discharge hole 22 are brought into communication through the annular groove 25, while the control hole 23 and the through hole 24 are brought into alignment.

The communication hole 21 described above is always open to the sub-port 26 which communicates with the rod side chamber 31 of the cylinder via the conduit 30, and the discharge hole 22 is always open to the second tank port 27.

Further, the poppet 18 is normally closed by the action of a control spring 32, and when opened against the control spring 32, a back pressure chamber 33 on the side of the spring 20 is opened.
is communicated with the second tank port 27 via the hole 34.

In the figure, reference numerals 35 and 36 are check valves, and 37 is a throttle.

However, when the spool 2 is moved rightward in Figure 1, the communication hole 4 is closed as described above, and the pressure oil from the pump 7 is transferred to the piston side chamber
9 and causes the cylinder 28 to move upward.

At this time, the load pressure of the cylinder 28 is
If the pressure is lower than the set pressure determined in step 2, the rod side chamber 3
The return oil of No. 1 flows into the piston side chamber 29 via the check valve 35 and increases the cylinder's rising speed.

When the load pressure becomes higher than the set pressure, the poppet 18 is opened by the pressure oil from the pump 7, resulting in the state shown in FIG. 2. That is, poppet 18
When the main valve 17 opens, the back pressure chamber 33 communicates with the second tank port 27, so a pressure difference is generated before and after the orifice 19, and the main valve 17 moves against the spring 20.

When the main valve 17 moves as described above,
The communication hole 21 and the discharge hole 22 communicate with each other, and the return oil from the rod side chamber 31 returns to the tank 38 from the second tank port 27. Therefore, the cylinder 28 is raised only by the amount of oil discharged from the pump 7, and the rising speed is slower than in the case described above.

Once the main valve 17 moves as described above, even if the load pressure fluctuates,
The main valve 17 does not return to its original position for the following reason.

That is, when the main valve 17 moves, the control hole 23 and the through hole 24 communicate with each other, so that the back pressure chamber 3
3 maintains communication with tank 38. Therefore, even if the poppet 18 closes when the load pressure falls below the pressure set by the control spring 32, the differential pressure across the orifice 19 remains unchanged, so the main valve 17 maintains the moving state shown in FIG. 2. .

Since the main valve 17 does not return to its original position as described above, even if the load pressure fluctuates, the rod side chamber 3
The return oil of No. 1 is returned to the tank 38. In other words, the cylinder 28 slowly moves upward only by the amount of oil discharged from the pump 7.

In order to return the main valve 17 to its original position, the spool 2 must be returned to its neutral position.

Next, to lower the raised cylinder 28,
The spool 2 may be moved to the left in FIG.
When the spool 2 is moved to the left, the main port 3 and the third tank port 39 communicate with each other via the annular groove 11, so that the cylinder 28 uses its own weight to direct the oil in the piston side chamber 29 through the throttle 37. and return it to the tank 40.

At this time, oil from the tank 38 is sucked into the rod side chamber 31. In other words, since the sub-port 26 and the second tank port 27 communicate with each other via the groove 41 formed in the spool, oil from the tank 38 is sucked into the sub-port 26 and the second tank port 27.

[Brief explanation of drawings]

Drawings 1 and 2 show an embodiment of the present invention, in which Fig. 1 is a sectional view when the spool is in the neutral position, Fig. 2 is an enlarged sectional view of the main part when the spool is moved to the right, FIG. 3 is a circuit diagram showing a conventional device. 2... Spool, 7... Pump, 16... Sequence valve chamber, 17... Main valve, 18... Poppet, 19... Orifice, 23... Control hole,
24... Through hole, 28... Cylinder, 29... Piston side chamber, 33... Back pressure chamber, 38... Tank.

Claims (1)

[Claims] 1. A control valve is disposed between the pump and the cylinder to control the switching operation of supplying and discharging pressure oil to the cylinder, and also prevents communication between the rod side chamber and the tank when the load pressure of the cylinder is below the set pressure. A sequence valve mechanism is provided that shuts off the piston and switches the rod side chamber to the tank when the load pressure exceeds the set pressure. In a cylinder control device equipped with a check valve that allows flow only from the side chamber to the piston side chamber, a sequence in which oil discharged from the pump is supplied into the spool of the control valve when the spool is switched in one direction. It forms a valve chamber, and this valve chamber houses a main valve with an orifice and a poppet that opens when the pressure exceeds the set pressure.When the poppet opens and the main valve moves to a predetermined position, the cylinder A cylinder control device configured to communicate a back pressure chamber of the main valve with the tank by communicating a rod side chamber of the main valve with the tank and at the same time communicating a control hole formed in the main valve with a through hole of the spool.