JPH07766Y2 - Hydraulic circuit for rotation control - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a hydraulic circuit for rotation control which requires low torque high speed rotation and low speed high torque rotation, and is particularly suitable for a separator, and is suitable for a dehydration separation. The present invention relates to a rotation control hydraulic circuit capable of obtaining low-torque high-speed rotation and high-torque low-speed rotation during scraping.

(Prior Art) A conventional hydraulic circuit for centrifuge rotation control is, for example,
June 15, 1981 Issued by Japan Machinist Co., Ltd. "New edition: Hydraulic pressure to be known / Applications" (author Fujikoshi Hydraulics Research Group), page 45 disclosed as shown in FIG.

That is, the hydraulic motor 16, a closed circuit formed by a variable discharge piston pump 2 having a discharge port and a suction port communicating with an inlet and an outlet of the hydraulic motor, and a boost pump 1 for supplying and exchanging pressure oil to the closed circuit. ′ And flushing valve
22 '. The pressure oil in the main circuit during operation flows in the closed circuit as shown by the solid line arrow, and the boost pump 1'is supplied with pressure oil and the flushing valve 22 '(the valve automatically switches to the left position during operation). The pressure oil for the pressure oil exchange had a flow like a dotted arrow. The screen basket of the centrifuge is rotated at high speed by the hydraulic motor 16 and requires a low speed rotation control for dewatering and scraping. For example, if raw water such as sludge is supplied into a screen-shaped basket and a hydraulic motor for rotating the screen-shaped basket (hereinafter referred to as a hydraulic motor) is rotated at high speed,
It is dehydrated by the centrifugal action, and then the sludge in the basket is pushed by the inner wall and solidified. In order to scrape off this solidified sludge with a separately installed blade, it is necessary to rotate the hydraulic motor with high torque and low speed. In this case, the rotation control of the hydraulic motor 16 shown in FIG.
Was done in closed circuit control using. The rotation speeds of these centrifuges are as shown in the process cycle diagram of FIG.
Normally, the rotation speed during dehydration separation requires a high speed of 1500 rpm,
A low rotation speed of 50 rpm is required for scraping. Therefore, the pump discharge rate needs to be the flow rate corresponding to the above rotation, and especially when scraping, it is about 1/30 (about 3%) as described above.
Only the discharge amount of is required. Under such a condition, the conventional variable displacement piston pump 2 of the hydraulic system and the surrounding pressure control valve 20 'have a drawback that a smooth low speed rotation cannot be obtained due to the following reasons. It was
That is, (I) In a general commercial product, the minimum discharge amount of the variable discharge piston pump 2 is limited to 30 to 40% of the maximum discharge amount, and if the discharge amount is less than this, the flow rate fluctuation becomes large and the hydraulic motor Cause uneven rotation. That is, the efficiency is extremely lowered, and the change in the oil viscosity due to the change in the oil temperature greatly affects the drain amount, etc., and a stable required discharge amount cannot be secured. Therefore, a separate hydraulic device for scraping was required.

(II) In the pressure control valve 20 ', etc., in order to obtain stable pressure, the maximum flow rate of 30% is required for small valves (equivalent to 3 / 8B).
%, The flow rate of 10% or more is the minimum required flow rate for large valves (equivalent to 1 / 2B or more). Therefore, at a small flow rate, as in the case of the pump, the oil temperature changes, the flow rate from the valve and the main body is adversely affected, and the pilot pressure inside the valve cannot be obtained. Become.

(III) In the flushing valve 22 ', the switching pressure becomes unstable at a small flow rate due to the same reason as described above, so-called fluctuation occurs, a reliable flushing exchange operation cannot be obtained, and deterioration of oil in the closed circuit progresses. .

For this reason, the controllability of the hydraulic system is poor, and uneven rotation occurs when the hydraulic motor 16 rotates at high torque and low speed, and becomes unstable. This is directly transmitted to the screen-like basket, causing system vibration and noise, and And the scraping blade was damaged, resulting in a shortened machine life.

(Problems to be solved by the invention) The object of the present invention is to obtain an appropriate low torque high-speed rotation that solves the drawbacks of conventional products, and to rotate at an extremely low speed such as when scraping a centrifuge. Rotation requiring high torque can be obtained without rotation unevenness, and unstable flushing of the pressure control valve etc. due to supply of an extremely small amount of pressure oil to the hydraulic motor at low speed rotation and flushing replacement due to fluctuation of the flushing valve etc. An object of the present invention is to provide a rotation control hydraulic circuit that eliminates the inconvenience.

(Means for Solving the Problems) For this reason, the present invention relates to a closed circuit formed by a hydraulic motor 16 and a variable discharge pump 2 having a discharge port and a suction port communicating with an inlet and an outlet of the hydraulic motor, In a rotation control hydraulic circuit including a boost pump 1 and a flushing valve 22 for replenishing and exchanging pressure oil to the closed circuit, the variable discharge pump 2 causes the switching device 100 to make the discharge amount substantially zero.
The boost pump 1 includes a variable discharge pump that has a high pressure and a small capacity and reduces the discharge amount when the discharge pressure rises, and the inlet side oil passages 15 and 17 of the hydraulic motor 16 have hydraulic pressure at their outlets. A circuit backflow prevention valve 18 that blocks the inflow of pressure oil from the oil passage 15 toward the motor inlet to the oil passage 17 is arranged, and the sequence is performed from one of the switching valves 7 provided in the discharge passage of the boost pump 1. A circuit connected to both ports of the variable discharge pump 2 via a valve 8 constitutes a boost circuit (supplementary circuit), and the other of the switching valves 7 is a flow rate adjusting valve.
A circuit connected to the outlet of the circuit check valve 18 via 14 is provided, and the pilot path 28 of the flushing valve 22 is connected to the pilot path 28 and the return circuit 31 ′ of the hydraulic motor 16 or the tank 4. A switching valve 29 is provided for connecting to either one of the return circuits 25, and an open circuit is constituted by the return circuit to the tank and the circuit constituted by the flow rate adjusting valve 14 to enable high torque low speed rotation. The hydraulic circuit for rotation control is characterized in that

(Embodiment) Next, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the variable displacement piston pump 2 includes a remote control unit 100 that is a well-known switching device that switches the displacement to substantially zero. Circuit 17 is a circuit check valve 18
Through the oil passage 15 to the hydraulic motor 16, and the return side of the hydraulic motor 16 is returned to the suction side of the variable discharge piston pump 2 via the return circuit 31 ′ and the oil passage 31. They are communicated with each other to form a so-called closed circuit.

A closed circuit pressure setting relief valve 9 branched from the oil passage 17 and connected is provided between the oil passage 17 and the oil passage 31 forming the closed circuit. Further, the pressure setting relief valve 9 is connected to the oil passage 31 via the oil passage 10 and the check valve 19, and the oil passage 17
The excess oil is returned to the suction port of the variable discharge piston pump 2.

Between the oil passage 17 and the oil passage 15 on the inlet side of the hydraulic motor 16, a check valve 18 (alternatively, another circuit check valve such as a solenoid valve may be used) is arranged as a circuit check valve. Oil passage
15 pressure oils are prevented from flowing into the oil passage 17.

The brake valve 20 is connected between the oil passage 15 and the return circuit 31 'with the high pressure side port being the return circuit 31' side.
Return circuit 3 by inertial force when braking 16 or stopping
1 ', the surge pressure generated in the oil passage 31 is released to the oil passage 15 side,
It is designed to prevent the occurrence of abnormal pressure and to prevent damage to surrounding pipes and valves.

The boost pump 1 is formed of a well-known variable discharge piston pump which has a high pressure and a small capacity and reduces the discharge amount when the discharge pressure rises. The boost pump 1 is integrally formed with the variable discharge piston pump 2 and is connected to the electric motor 3 so as to suck oil from the tank 4 through the suction filter 5.

After the pressure oil of the boost pump 1 passes through the check valve 6,
It is branched and connected to a pressure reducing valve for supplying control pressure to the switching device 100 of the variable discharge piston pump 2 and a solenoid valve 7 which is a switching valve.

A sequence valve 8 and a flow rate adjusting valve 14 are provided at the outlet of the solenoid valve 7.
When the solenoid valve 7 is connected and the solenoid valve 7 is off, the check valve 6 and the solenoid valve 7 are connected to the discharge side of the pump 1 as shown in FIG.
Connected to the sequence valve 8 and further connected to both ports of the variable discharge piston pump 2 via the tank line 10 of the relief valve 9 for setting the pressure of the closed circuit and the check valves 19 and 30. (Supply circuit) is configured. The set pressure of this boost circuit is the relief valve connected to the circuit 11 between the solenoid valve 7 and the sequence valve 8.
It is configurable by 12. The sequence valve 8 is for securing the control pressure of the switching device 100.

When the solenoid valve 7 is turned on, the discharge oil of the pump 1 passes through the check valve 6, the solenoid valve 7, the oil passage 13, the flow rate adjusting valve 14, and the circuit check valve as shown in FIG. A scraping (high torque / low speed rotation) circuit is configured by being connected to the outlet side of the (check valve) 18 and the oil passage 15 between the hydraulic motors 16.

The pump 1 has a pressure compensation mechanism (compensator) inside, and the pressure of the circuit can be set by the pump 1.

The discharge flow rate of the pump 1 is designed to decrease when the pressure becomes high, but the flow rate adjusting valve 14 can regulate the flow rate.

Flushing valve 22 between oil passage 15 and return circuit 31 '
The oil passage 15 is branched and connected to the oil passage 21 of the flushing valve 22 and the pilot passage 27. Further, the return circuit 31 'and the oil passage 26 of the flushing valve 22 are branched and connected.

Further, the pilot passage 28 of the flushing valve 22 is connected to the return circuit 31 'when the solenoid valve 29 is off and the return circuit 25 to the tank 4 when the solenoid valve 29 is on, via the solenoid valve 29.
It is designed to be connected with.

During the closed circuit operation shown in FIG. 1, the solenoid valve 29 is turned off and the pilot path 28 and the return circuit 31 'are in communication. Oilway 15
Is higher than the pressure in the return circuit 31 ', the flushing valve 22 is moved to the left position by the pressure oil in the pilot passage 27, and the excess oil in the oil passage 26 is removed by the oil passage 23 and the pressure holding relief valve 24.
Through the return circuit 25 to the tank 4.
If the pressure in the return circuit 31 'is higher than the pressure in the oil passage 15, the pressure oil in the pilot passage 28 causes the flushing valve 22
Is set to the right position, and excess oil in the oil passage 21 is returned to the return circuit 25 to the tank 4 via the oil passage 23 and the pressure-holding relief valve 24.

When the solenoid valve 29 is turned on as shown in FIG. 2, the pressure oil in the pilot passage 28 is communicated with the return circuit 25 to the tank 4 via the solenoid valve 29, so that the flushing valve 22 is In the figure, it is always set to the left position, and oil passage 26 is the oil passage.
23, connected to a return circuit 25 to the tank 4 via a pressure-holding relief valve 24. That is, the oil discharged from the pump 1 is constantly returned to the tank via the hydraulic motor 16, and the scraping (high torque, low speed rotation) circuit shown in FIG. 2 constitutes an open circuit.

Next, the operation of the embodiment will be described with reference to FIGS. 1 to 3 showing hydraulic circuit diagrams.

When the electric motor 3 is started, the boost pump 1 and the variable discharge piston pump 2 rotate, and a high-pressure large-capacity hydraulic motor
16 rotates. When, for example, raw water of sludge is supplied into the screen basket when the rotation speed reaches high speed, dehydration is performed from the inside of the screen basket, and solid sludge remains in the basket. Therefore, the discharge amount of the variable discharge type piston pump 2 is reduced to perform braking as shown in FIG. After that, the solidified and hardened sludge is scraped at low speed by using a scraping blade tool separately installed.

More specifically, during high-speed rotation (during dehydration separation), as shown in FIG. 1, the pressure oil discharged from the discharge port of the variable discharge piston pump 2 whose flow rate is set by the switching device 100 is To the oil passage 17, the check valve 18, the oil passage 15, and the hydraulic motor 16, and the hydraulic motor is rotated at a high speed at a predetermined rotation speed for dehydration separation. The return oil from the hydraulic motor 16 returns to the suction port of the variable displacement piston pump 2 via the return circuit 31 'and the oil passage 31.

When pressure oil is guided to the hydraulic motor 16 and the hydraulic motor 16 starts rotating, the oil passage 15 side becomes the load side, and the pilot circuit 27 of the flushing valve 22 is connected to the oil passage 21 connected to the oil passage 15.
The pressure oil is introduced via the pressure oil, the flushing valve 22 is switched by this pressure oil, and the excess oil on the oil passage 26 side passes through the oil passage 23, the pressure setting relief valve 24, and the oil passage 25 to the tank 4 Returned to.

On the other hand, at this time, the solenoid valve 7 is turned off, and the pressure oil from the boost pump 1 is replenished to the oil passage 31 via the solenoid valve 7, the sequence valve 8, and the check valve 19 which are in the off state to supply the boost circuit. The oil in the closed circuit is replaced.

During braking, the tilt angle of the swash plate for controlling the discharge amount of the variable discharge piston pump 2 is controlled by the switching device 100 to reduce the discharge amount as shown in the process cycle of FIG. 3 for braking.
Return circuit on the output side of the hydraulic motor 16 due to inertial force during braking
31 ', the oil passage 31 is increased in pressure. At this time, the solenoid valve 29 is in the off state, and the pressure oil in the return circuit 31 'that has been increased in pressure is released by the solenoid valve.
29 and pilot line 28, flushing valve 22
To the right position in the figure, the oil passage 15 is a flushing valve 22,
It communicates with the tank 4 via an oil passage 23, a pressure-holding relief valve 24, and a return circuit 25.

In this state, the oil from the boost pump passes through the solenoid valve 7, the sequence valve 8 and the check valve 30 in the off state to the oil passage.
It is connected to 17 and guided into a closed circuit. In this way, when the hydraulic motor 16 rotates at high speed and during braking, the boost pump 1 and the flushing valve 22 replace the oil in the closed circuit.

Next, the high torque low speed rotation (in the scraping state) will be described. As shown in FIG. 3, braking is applied from the high speed rotation during the centrifugal action, and the rotation speed is gradually reduced. At this point, an electric signal separately installed is output, the solenoid valve 7 is turned on as shown in FIG. 2, and the discharge amount of the variable discharge piston pump 2 is tilted by the swash plate for controlling the discharge amount. The angle is set to almost 0 by the remote control unit 100, and oil is not sucked or discharged between the oil suction side oil passage 31 and the discharge side oil passage 17 of the variable discharge amount piston pump 2. Therefore, the low speed rotation of the hydraulic motor 16 during the scraping work is performed by only the small capacity of the pump 1, and the flow of the pressure oil flowing through the circuit is as shown by the arrow in FIG.

That is, the pressure oil from the pump 1 is sent to the hydraulic motor 16 via the oil passage 13, the flow rate adjusting valve 14, and the oil passage 15 on the outlet side of the check valve 18. The rotational speed of the hydraulic motor varies depending on the material of the scraped material, but the desired rotational speed can be easily obtained by controlling the discharge flow rate of the boost pump with the flow rate adjustment valve 14, and the hydraulic motor scrapes. The object is rotated at a rotation speed corresponding to the object, for example, 50 rpm.

In addition, the flushing valve 22 has the same oil passage as at high speed rotation.
The oil passage 21 connected to 15 and the pilot oil passage 27 are switched to operate so that the oil in the return circuit 31 'from the hydraulic motor is returned to the tank 4 via the flushing valve 22 and the like. As shown, the solenoid valve 29 is turned on,
The flushing valve 22 is operated to forcibly return the oil in the return circuit 31 'from the hydraulic motor to the tank 4 by the solenoid valve 29, and an open circuit is always constructed.

Therefore, the oil introduced into the circuit of the hydraulic motor is constantly flushed by the flushing valve 22 during the closed circuit and open circuit operations.
Are replaced by the oil, and the pressure oil is confined in a closed circuit, resulting in deterioration of the oil itself and the rise in the oil temperature, which adversely affects the pumps, valves, and even the machine body in the system. There is no.

Further, at the time of high torque low speed rotation, the flushing valve is forcibly set to the fixed position even when the flow rate is small due to the pump 1, so the flushing is caused by the load fluctuation during the scraping of the clean basket rotation hydraulic motor 16. The valve 22 does not fluctuate. Further, since the pressure oil supplied to the oil passage 15 by the circuit backflow prevention valve (check valve) 18 is separated from the large-capacity relief valve 9 that sets the pressure of the closed circuit, in the case of a small flow rate by the pump 1. However, pressure instability does not occur. Therefore, even when scraping, the small flow rate control by the flow rate adjusting valve 14 and the pump 1
The stable high torque low speed rotation is possible by the high pressure control of the pressure gauge 32. The pressure gauge 32 is for confirming the set pressure of the boost circuit system and the pressure gauge 33 is for confirming the set pressure of the closed circuit system. Further, as the switching device 100, various devices such as electric control and remote control are used.

(Effects of the Invention) As described above, according to the present invention, a power source and a boost pump for one system can be used instead of a power source and a boost pump for two circuits for a closed circuit and an open circuit. , Moderate low torque high speed rotation can be obtained, and, for example, when scraping a centrifuge, extremely low speed rotation and rotation requiring high torque can be obtained without rotation unevenness,
In addition, a rotation control hydraulic circuit that eliminates the instability of the pressure control valve and the like due to the supply of an extremely small amount of pressure oil to the hydraulic motor at low speed rotation and the inability to obtain flushing replacement due to fluctuations in the flushing valve etc. It became something to do.

Furthermore, the present invention does not require a special pump or valve,
Pumps and valves with general marketability can be applied, stable functions are always obtained, maintenance is easy, and product quality is stable without causing deterioration of environment due to vibration and noise and shortening of machine life. .

Further, since the two-system power source is one system, the weight is reduced, and it is compact and easy to handle.

High-speed rotation low torque and low-speed rotation high torque for each process can be set appropriately by the switching valve for each process, so the control sequence is simple and always stable and smooth control of the hydraulic motor works reliably and smoothly. It is extremely useful because it has the advantage that it can be done.

[Brief description of drawings]

1 and 2 are hydraulic circuit diagrams showing the operating states of the centrifuge rotation control hydraulic circuit according to the embodiment of the present invention at the time of dehydration separation and at the time of scraping, respectively, and FIG. 3 is a centrifugal separator. An operation cycle diagram, FIG. 4 is a hydraulic circuit diagram of a conventional rotation control hydraulic circuit. 1 ... Pump (boost pump), 2 ... Variable discharge piston pump (variable discharge pump), 4 ... Tank, 7
...... Solenoid valve (switching valve), 8 …… Sequence valve, 14 …… Flow rate adjusting valve, 15 …… Oil passage, 16 …… Hydraulic motor, 17 …… Oil passage, 18 …… Check valve (circuit check valve) ), 22 …… flushing valve, 25 …… return circuit, 28 …… pilot path, 29 …… solenoid valve (switching valve), 31 ′ …… return circuit, 100
...... Switching device.

Claims (1)

[Scope of utility model registration request] 1. A closed circuit formed by a hydraulic motor 16 and a variable discharge pump 2 having a discharge port and a suction port communicating with an inlet and an outlet of the hydraulic motor, and a boost for replenishing and exchanging pressure oil to the closed circuit. Pump 1 and flushing valve 22
In the rotation control hydraulic circuit including, the variable discharge pump 2 includes a switching device 100 that makes the discharge amount substantially zero, and the boost pump 1 has a high-pressure small-capacity and the discharge amount increases when the discharge pressure increases. A circuit backflow prevention valve 18 having a variable discharge pump for reducing the oil pressure is provided in the inlet side oil passages 15 and 17 of the hydraulic motor 16 so that the outlet thereof faces the inlet of the hydraulic motor. A circuit connected from one of the switching valve 7 provided in the discharge passage to both ports of the variable discharge pump 2 via the sequence valve 8 and the other circuit of the switching valve 7 from the other side via the flow rate adjusting valve 14. A circuit connected to the outlet of the check valve 18 is provided, and
A switching valve that connects the pilot passage 28 to the pilot passage 28 of the flushing valve 22 and either the return circuit 31 'of the hydraulic motor 16 or the return circuit 25 to the tank 4.
29. The hydraulic circuit for rotation control is provided with 29.