JPH0276905A - Control circuit for hydraulic cylinder - Google Patents

Abstract

PURPOSE:To supply a large flow to a cylinder by means of a small pump by arranging a regeneration passage joining from the upper stream side of the orifice in an outflow passage through a check valve to the inflow passage of a working liquid flowing to the liquid room located on the side opposite to a piston rod. CONSTITUTION:A four ways valve 25 determines the working direction of a hydraulic cylinder 20 and a flow and pressure adjusting valves 24A, 24B controlled by a controller 27 control the drive force and drive speed of the hydraulic cylinder 20. In the case of the extension of the hydraulic cylinder, a working liquid flows in a liquid room B located on the side opposite to a piston rod 35 from a hydraulic source 22, meantime it flows out from a liquid room A located on a piston rod side to a reservoir 26. A regeneration passage 46 branched on the upper stream side of an orifice 43 interposed in this outflow passage 42 supplies a part of the working liquid flowing out from the liquid room A located on the piston rod side to the inflow passage 44 to the liquid room B located on the side opposite to the piston rod and the inflow amount to the oil room B located on the side opposite to the piston rod is increased. Thus, the hydraulic cylinder can be extended quickly by using a small pump.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvements in control circuits for hydraulic cylinders used in industrial machines and construction machines.

(Prior Art) Hydraulic cylinders used in industrial machines such as injection molding machines and press machines, and construction machines such as AM machines and cranes are controlled by a control circuit as shown in FIG. 4, for example.

That is, 1 is a hydraulic cylinder as a hydraulic cylinder,
Oil chambers A and B on both sides of the piston 2 are connected to a hydraulic pump 5 via a switching valve 4 that determines the operating direction of the piston rod 3.

Between the hydraulic cylinder 1 and the switching valve 4, there is a flow control valve (variable orifice) 6 for performing meter-in control (pressure and flow rate control on the supply side) on the inflow side and the outflow side, respectively.
A and 6B, and flow control valves (variable orifices) 7A and 7B for meter-out control (pressure and flow rate control on the return side) are interposed, and the flow control valves 6A and 6B on the meter-in side are connected to bypass passages. There are check valves 8A and 8B that allow the flow of oil on the return side, and check valves 9A and 9B that allow the flow of oil on the supply side are interposed in the bypass passages of the meter-out side flow control valves 7A and 7B, respectively. will be equipped.

For example, when the switching valve 4 is switched to the contraction side when the hydraulic cylinder 1 is operating on the contraction side, the piston rod 3 is caused to contract by the pressure oil supplied to the oil chamber A.

In that case, meter-in 1ull can be performed by adjusting the flow rate control valve 6A on the inflow side. Further, meter act control can be performed by setting the flow 1 control valve 7B on the outflow side to 114g if necessary.

In addition, IOA is oil chamber A11ll, and IOB is oil chamber B.
11 is a pressure reducing valve that reduces the hydraulic pressure from the hydraulic pump 5 to a set value; 12 is a relief valve that regulates the maximum discharge pressure of the hydraulic pump 5; 6 (Problems to be solved by the invention); In the control circuit, the flow rate of hydraulic oil flowing in and out of the oil chamber B on the side opposite to the piston rod 3 of the hydraulic cylinder 1 always exceeds the flow rate of hydraulic oil simultaneously flowing in and out of the oil chamber A on the piston rod 3 side. Therefore, when it is desired to extend the hydraulic cylinder 1 at high speed, the flow rate of hydraulic oil sent to the oil chamber B is as follows:
In order to contract the hydraulic cylinder 1 at the same speed, it was necessary to use a hydraulic pump 5 with a large discharge rate, which was larger than the flow rate of the hydraulic oil sent into the oil chamber A, and to ensure the expansion speed.

SUMMARY OF THE INVENTION In view of these problems, it is an object of the present invention to provide a control circuit that is capable of various controls and that can supply a large flow rate to a cylinder using a small pump.

(Means for Achieving the Object) The present invention provides a four-way valve that selectively connects a liquid chamber on the piston rod side and a liquid chamber on the opposite side inside a hydraulic cylinder to a hydraulic pressure source and a reservoir; Equipped with a valve that adjusts the flow rate and pressure of the working fluid between the valve and each of the liquid chambers, and a controller that controls the valve by signal output,
An orifice is provided in the middle of the outflow passage for the hydraulic fluid that flows out from the liquid chamber on the piston rod side of the hydraulic cylinder via the four-way valve, and this outflow passage is provided in the inflow passage for the hydraulic fluid to the liquid chamber on the opposite side of the piston rod. It is equipped with a regeneration passage that joins from the upstream side of the orifice via a check valve.

(Operation) The four-way valve determines the operating direction of the hydraulic cylinder, and the flow rate and pressure regulating valve controlled by the controller controls the driving force and driving speed of the hydraulic cylinder.

When the hydraulic cylinder is extended, hydraulic fluid flows from the hydraulic pressure source into the fluid chamber on the opposite side of the piston rod, and at the same time, hydraulic fluid flows out from the fluid chamber on the piston rod side into the reservoir. A regeneration passage that branches on the upstream side of the orifice installed in this outflow passage replenishes a portion of the working fluid that has flowed out from the liquid chamber on the piston rod side to the inflow passage to the liquid chamber on the opposite side of the piston rod, and Increase the amount of flow into the oil chamber on the opposite side of the rod.

(Example) Embodiments of the present invention are shown in FIGS. 1 to 3.

In FIG. 1, reference numeral 20 denotes a hydraulic cylinder, in which oil chambers A and B formed in a piston 21 connected to a piston rod 35 are selected as a hydraulic pump 22 and a reservoir 26 via a four-way valve 25. connected.

A poppet-type cartridge valve 24A that responds to pilot pressure is located between the four-way valve 25 and the oil chamber A.
A similar cartridge valve 24B is installed between the oil chamber B and the oil chamber B as a valve for adjusting flow rate and pressure.

The four-way valve 25 connects the cartridge valve 24A to the hydraulic pump 22 and connects the cartridge valve 24B to the reservoir 2.
Shrinking bonoshi connecting to 6! an extended position b that connects the cartridge valve 24B to the hydraulic pump 22 and the cartridge valve 24A to the reservoir 26;
It is a solenoid valve equipped with a neutral secretin C that releases both of these into the reservoir 26, and is switched and controlled by a command from a controller 27, which will be described later.

Cartridge valve 2 of extension bonoshishin b of four-way valve 25
An orifice 43 is provided in the outflow passage 42 connecting 4A to the reservoir 26. Further, the upstream side of the orifice 43 of the outflow passage 42, that is, the cartridge valve 24A side, and the inflow passage 44 that connects the cartridge valve 24B to the hydraulic pump 22 are connected by a regeneration passage 46, and a check valve 45 is provided in the middle thereof. .

Cartridge valves 24A and 24B are hydraulic cylinders 20
A poppet valve 29 is slidably housed in the cylinder 28, and the poppet valve 29 controls the pressure and flow rate of the poppet valve 2.
9 increases or decreases the passage area communicating the hydraulic cylinder 20 and the four-way valve 25 in response to the pilot pressure supplied to the pilot chamber 40 or 41. These pilot pressures are supplied via electro-hydraulic servo valves 30A and 30B that connect hydraulic pump 22 and reservoir 26 to pilot chambers 40 and 41 under direction and opening control based on commands from controller 227. be done.

P1 to P, the controller 27 detects the pressure upstream and downstream of the poppet valve 29 of the cartridge valves 24A and 24B.
a pressure sensor that outputs a pressure signal to the poppet valve 2;
This is a position sensor that detects the displacement position of 9 and outputs a position signal to the controller 27.

A command input device (not shown) is attached to the controller 27, and it switches the west valve 25 based on the command from the command input device, and also specifies the opening degrees of the cartridge valves 24A and 24I3 via the servo valves 3OA and 30B. The displacement position of the poppet valve 29 and the pressure sensor P are adjusted according to the control details.

~P, respectively perform feedback control based on the detected pressure.

34A and 34B are relief valves that prevent an abnormal increase in pressure in the circuit when, for example, a force is applied to the piston rod 35 from the load system side while the hydraulic cylinder 20 is stopped, and 36A and 36B are oil chamber A. In order to prevent air bubbles from forming in the oil chambers A and B, the reservoir 26
37 is a relief valve that regulates the maximum discharge pressure of the hydraulic pump 22.

Next, the effect will be explained.

Hydraulic cylinder 204: To operate to the contraction side, operate the hydraulic pump 22 and input a command from the input device, then the CI-227 switches the west valve 25 to the contraction cylinder 3a and The discharge oil of the hydraulic pump 22 is supplied to the oil chamber A of the hydraulic cylinder 20 through the cartridge valve 24A, and at the same time, the hydraulic oil in the oil chamber B passes through the cartridge valve 24B and is supplied to the reservoir 26 via the west valve 25. leaks to.

At this time, the controller 27 includes a pressure sensor P.

The pressures p1 to p detected by ~P, and the displacement position (opening degree) of the poppet valves 29 of the cartridge valves 24A and 24B detected by the position sensor 48 are input as signals, and based on these, the controller 27 inputs the signals. Performs various controls specified via the device.

For example, the inflow and outflow flow rates of the hydraulic cylinder 20 are controlled as follows.

First, the controller 27 calculates the flow fiQ of the cartridge valve 24A as follows based on the detected pressures p and p and the opening degree x of the poppet valve 29 detected by the position sensor 48.

Q = K-A (x)i However, K: Flow rate coefficient A (x): Oil flow cross-sectional area of poppet valve 29 (calculated from m degrees X) Controller 27 compares this flow rate Q with command flow rate Q0 However, when these do not match, a signal is output to the servo valve 3o that drives the poppet valve 29 so that the poppet valve 29 of the cartridge valve 24A increases or decreases the oil passage cross-sectional area A (x) in the direction of bringing Q closer to Qo. , By feeding back the flow rate Q calculated from the input signal to the opening degree control of the poppet valve 29, the flow rate Q becomes the command flow rate Q0.
matches. Note that meter-out control of the flow rate in the cartridge valve 24B is also performed by pressure sensors P1 and P.

The same process is performed based on the opening degree of the poppet valve 29 determined from the pressures p1 and p2 detected by the position sensor 48 and the detected value of the position sensor 48.

Further, when pressure meter-in control is instructed, the controller 27 controls the pressure p in the oil chamber A detected by the pressure sensor P4.
, and the commanded pressure pno, p,〉p,. By outputting a signal to the servo valve 3OA to drive the bobbet valve 29 of the cartridge valve 24A in the closing direction in the case of p4 < 94°, the pressure p in the oil chamber A is set to the command pressure. p.

match. Further, in meter-out control of pressure in the cartridge 7 valve 24B, llz>pz.

In this case, the poppet valve 29 is opened in the opening direction, 92<1)2
In the case of .degree., a signal for driving the poppet valve 29 in the leap direction is output to the servo valve 30B.

On the other hand, the piston rod 35 pulls out the hydraulic cylinder 20.
For the expansion operation, meter-in control is performed by the cartridge valve 24B and meter-out control is performed by the cartridge valve 24A in the same process as described above.

Incidentally, since the cross-sectional area of the oil chamber B is larger than the oil chamber A by the amount of the piston rod 35, the amount of inflow required into the oil chamber B exceeds the amount of flow out from the oil chamber A during the extension operation of the hydraulic cylinder 20. On the other hand, the extension valve 1 of the four-way valve 25
In channel b, an orifice 43 provided in the outflow passage 42
provides resistance to the hydraulic oil flowing out from the oil chamber A, and causes a part of the hydraulic oil to flow into the inflow passage 44 via the regeneration passage 46 that branches from the upstream side of the orifice 43. For this reason,
During the extension operation, hydraulic oil in an amount equal to or greater than the discharge amount of the hydraulic pump 22 is supplied to the oil chamber B, and the hydraulic cylinder 20 quickly extends.

FIG. 2 shows another embodiment in which a regeneration passage 46 is provided outside the four-way valve 25, and a cutoff valve 47 that is switched by pilot pressure is interposed in the regeneration passage 46. That is, when the pressure p on the cartridge valve 24B side becomes higher than a certain level during the extension operation, the cutoff valve 47 is switched and the check valve 4
The regeneration passage 46 is communicated through the regeneration passage. Further, during the contraction operation, since the pressure p+ is low, the shutoff valve keeps the regeneration passage 46 in a closed state and prevents the oil discharged from the hydraulic pump 22 from escaping from the regeneration passage 4G to the outflow side.

FIG. 3 also shows a two-way servo valve 31A in place of the cartridge valves 24A and 24B and servo valves 3OA and 30A shown in FIG. 1 as valves for adjusting flow rate and pressure.
and 31B, and in this example also the first
The same effect as the embodiment shown in the figure can be obtained.

(Effects of the Invention) As described above, the present invention provides a west valve that selectively connects a liquid chamber on the piston rod side and a liquid chamber on the opposite side inside a hydraulic cylinder to a hydraulic pressure source and a reservoir; a valve that adjusts the flow rate and pressure of the working fluid between the four-way valve and each of the liquid chambers;
Since it is equipped with a controller that controls this valve, it is possible to perform various controls such as controlling the operating direction of the hydraulic cylinder and meter-in and meter-out control of flow rate and pressure.

In addition, an orifice is provided in the middle of the outflow passage for the working fluid from the fluid chamber on the piston rod side of the hydraulic cylinder, and an
Since the inflow passage for hydraulic fluid into the liquid chamber on the opposite side of f7t' is equipped with a regeneration passage that joins from the upstream side of the orifice of this outflow passage via a check valve, when the hydraulic cylinder is extended, the fluid on the piston rod side is A part of the hydraulic fluid flowing out of the chamber joins the hydraulic fluid from the hydraulic pressure source flowing into the fluid chamber on the opposite side of the piston rod through this regeneration passage, increasing the amount of hydraulic fluid flowing into the hydraulic cylinder. can be expanded rapidly.

[Brief explanation of the drawing]

@ Fig. 1 is a control circuit diagram showing an embodiment of the present invention, Fig. 2 is a control circuit diagram showing another embodiment, and Fig. 3 is a control circuit diagram showing still another embodiment. Further, FIG. 4 is a control circuit diagram showing a conventional example. 20... Hydraulic cylinder, 22... Hydraulic pump, 24
A, 24B...Cartridge valve, 25...Four-way valve, 26...Reservoir, 27...Controller, 2
9...Poppet valve, 3OA, 30B...Servo assembly,
42... Outflow passage, 43... Orifice, 44...
- Inflow passage, 45... Check valve, 46... Regeneration passage, A, B... Oil chamber.

Claims (1)

[Claims] A four-way valve selectively connects a liquid chamber on the piston rod side and a liquid chamber on the opposite side inside the hydraulic cylinder to a hydraulic pressure source and a reservoir; It is provided with a valve that adjusts the flow rate and pressure, and a controller that controls this valve by signal output, and is located in the middle of the outflow passage of the hydraulic fluid flowing out from the liquid chamber on the piston rod side of the hydraulic cylinder via the four-way valve. A hydraulic cylinder characterized in that an orifice is provided, and a regeneration passage is provided in an inflow passage for hydraulic fluid to a liquid chamber on the opposite side of the piston rod, which joins the outflow passage from the upstream side of the orifice via a check valve. control circuit.