JP3748954B2 - Hydraulic control circuit for viscous fluid pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic control circuit of a viscous fluid pump that sucks and discharges a viscous fluid such as concrete.
[0002]
[Prior art]
In the piston type viscous fluid pump, when either one of the two main hydraulic cylinders for fluid pumping moves forward and reaches the stroke end, the proximity sensor is activated to switch the suction and discharge of viscous fluid. It is known to switch valves (oscillating valves , slip valves, etc.) (hereinafter simply referred to as intake and discharge valves) and to switch the main hydraulic cylinder in the reverse direction.
[0003]
As an example, when the suction and discharge valves are of the swing valve type, as shown in FIG. 3, the head side pressure chambers of the two main hydraulic cylinders 1 and 2 are connected by a sealing line 3, and the two The rod side pressure chambers of the main hydraulic cylinders 1 and 2 and the tilted main oil pump 4 are connected by main pressure oil lines 5 and 6 to form a closed circuit, and a line 8 connected to the discharge side of the charge pump 7 The pressure oil guided from the charge pump 7 to the actuator 11 is connected to the actuator 11 for tilt adjustment through the servo valve 10 which is operated by switching the main circuit solenoid valve 9 which is an electromagnetic three-position valve. The direction is switched by switching the servo valve 10.
[0004]
Pressure oil that supplies pressure oil from the valve discharge pump 14 to the oscillating cylinders 12 and 13 that perform switching of the oscillating valve that is the suction discharge valve as the main hydraulic cylinders 1 and 2 alternately advance and retreat. A valve four-way valve 17 is provided in the middle of the pressure oil line 15 so as to be switched by the operation of the solenoid valve 16 for valve circuit, and swings when the valve four-way valve 17 is switched. The cylinders 12 and 13 are moved forward and backward to switch the swing valve. Further, the pressure oil line 18 is taken out from the middle of the pressure oil line 15 and an accumulator 19 is provided. Then, after sequentially passing through the variable throttle valve 20 and the pressure reducing valve 21, it is guided to the operating portion of the servo valve 10 through the main circuit solenoid valve 9. Reference numeral 23 denotes a check valve assembled in the oil discharge line 22 of the actuator 11 so that the discharge amount of the main oil pump 4 does not increase rapidly.
[0005]
In the above configuration, when the proximity sensors LS1 and LS2 provided at the forward stroke ends of the two main hydraulic cylinders 1 and 2 are alternately operated by the main hydraulic cylinders 1 and 2 moving forward alternately, Solenoid SOL. 1 or SOL. 2 is excited and the main circuit solenoid valve 9 is switched, so that the main oil pump 4 is reversed, and at the same time, the solenoid SOL. 3 or SOL. 4 is excited and the four-way valve 17 is switched, so that the forward and backward movement of the oscillating cylinders 12 and 13 is switched.
[0006]
[Problems to be solved by the invention]
However, in the hydraulic control circuit of the conventional viscous fluid pump, the main circuit solenoid valve 9 and the valve circuit solenoid valve 16 are switched at the same time when the proximity sensor LS1 or LS2 is operated, but their operations are independent of each other. Therefore, the tilt angle of the main oil pump 4 is switched in the reverse direction, and the suction / discharge valve is switched, and even if both operations are completed, the interruption of the pressure oil is eliminated. However, since a large pressure fluctuation occurs, there is a problem that the original effect of the closed circuit cannot be exhibited and pulsation occurs. That is, when the main circuit solenoid valve 9 is switched, the tilt angle of the main oil pump 4 is gradually reduced, and the suction discharge valve is switched in the process of increasing the tilt angle in the reverse direction from zero discharge amount. Since the timing is unstable, effective pressure fluctuation reduction has not been made. Furthermore, if any of the operations is delayed, the main oil pump 4 is normally operated to reversely rotate instantaneously, so there is a problem that the pulsation becomes larger. In addition, a check valve 23 is provided in the oil discharge line 22 of the actuator 11 in order to prevent the discharge amount of the main oil pump 4 from increasing suddenly. Therefore, it becomes dependent operation and pressure fluctuation cannot be reduced effectively.
[0007]
Accordingly, the present invention is intended to provide a hydraulic control circuit for a viscous fluid pump that can suppress a large pressure fluctuation during operation and reliably reduce pulsation.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention has a closed circuit in which pressure oil discharged from both tilting main oil pumps is alternately supplied to two main hydraulic cylinders, and the main oil pump An actuator for switching the tilt direction of the motor, a servo valve for switching the operating direction of the actuator, and a solenoid valve for a main circuit that is a three-position valve for operating the servo valve. In the hydraulic control circuit of a viscous fluid pump having a solenoid valve for a valve circuit for switching a suction / discharge switching valve for switching the suction / discharge of viscous fluid in accordance with the forward / backward movement of the main hydraulic cylinder, provided a proximity sensor and the stroke end near the stroke end of the hydraulic cylinder respectively, solenoid valve the main circuit neutral position by a signal of the proximity sensor in the vicinity of the stroke end Together to be switched on, so switching of the valve circuit for the solenoid valve by a signal of the proximity sensor of the stroke end is performed, further, by switching completion signal from the suction and discharge switching valve, communicating with the main circuit electromagnetic valve pressure oil to the main hydraulic cylinder is configured such that the so that switched to be supplied with is switched to the position tilting directions of the tilting main oil pump is switched.
[0009]
When the main hydraulic cylinder reaches the vicinity of the stroke end, the proximity sensor at that position is activated, and one solenoid of the main circuit solenoid valve is switched from the excited state to the demagnetized state, and the main circuit solenoid valve is switched to the neutral position. As a result, the discharge amount of the main oil pump is reduced to zero. When the main hydraulic cylinder reaches the stroke end near the discharge amount of zero, the suction discharge valve is switched by the signal of the proximity sensor at that position, and the other solenoid of the main circuit solenoid valve is excited based on the switching completion signal. By switching, the discharge amount of the main oil pump is increased. Therefore, there is no large pressure fluctuation and pulsation is reduced.
[0010]
The solenoid valve for the valve circuit is switched by a signal from the proximity sensor at the stroke end of the main hydraulic cylinder, the solenoid valve for the main circuit is switched to the communication position by the switching completion signal of the suction / discharge switching valve for the viscous fluid and the main hydraulic pressure is switched. Instead of switching to supply pressure oil to the cylinder, a timer that operates based on a signal from a proximity sensor near the stroke end of the main hydraulic cylinder can be used to switch the solenoid valve for the main circuit. A configuration may be adopted in which switching is performed so as to supply pressure oil to the main hydraulic cylinder .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
1 and 2 show an embodiment of the present invention. In the same configuration as the hydraulic control circuit of the viscous fluid pump shown in FIG. 3, a proximity sensor LS1 is provided at the forward stroke end of the main hydraulic cylinders 1 and 2. FIG. , LS2 is provided, proximity sensors LS1, LS2 are provided at positions slightly before the forward stroke end, proximity sensors LS3, LS4 are provided at the forward stroke end, and the proximity sensor LS1 or LS2 is activated. Sometimes solenoid SOL. 1 or SOL. 2 is demagnetized so that the main circuit solenoid valve 9 is switched to the neutral position, and when the proximity sensor LS3 or LS4 is activated, the solenoid SOL. 3 or SOL. 4 is excited to switch the valve circuit solenoid valve 16 so that the valve four-way valve 17 is switched.
[0013]
In addition, an unload valve 25 that can be switched by the operation of the solenoid valve 24 is provided in the middle of the main hydraulic lines 5 and 6, and further proximity sensors LS5 and LS6 are provided at the stroke ends of the oscillating cylinders 12 and 13, When the proximity sensor LS5 or LS6 is activated, the solenoid SOL. 2 or SOL. 1 is energized so that both tilting main oil pumps 4 are reversed, and when the proximity sensor LS5 or LS6 is activated, the solenoid SOL. 5 is excited to switch the electromagnetic valve 24 so that the unload valve 25 is switched to the open position.
[0014]
Now, when the main hydraulic cylinder 1 moves forward and the main hydraulic cylinder 2 moves backward, when the main hydraulic cylinder 1 reaches a position slightly ahead of the forward stroke end, the proximity sensor LS1 is activated and excited. The solenoid SOL. When 1 is demagnetized, the main circuit solenoid valve 9 is switched to the neutral position. As a result, the supply of the operating pressure oil to the servo valve 10 is cut off, and the actuator 11 is gradually returned to the neutral position, so that the discharge amount of the main oil pump 4 is gradually reduced and finally made zero. .
[0015]
Subsequently, when the main hydraulic cylinder 1 reaches the forward stroke end when the discharge amount of the main oil pump 4 is close to zero, the proximity sensor LS3 is activated, whereby the solenoid SOL. 3 is excited, the valve circuit solenoid valve 16 is switched, and the valve four-way valve 17 is switched, so that the forward and backward movements of the oscillating cylinders 12 and 13 are switched.
[0016]
Further, when the forward / backward movement of the swing cylinders 12 and 13 is switched and the swing cylinder 12 reaches the stroke end, the proximity sensor LS5 is operated, so that the solenoid SOL. 5 is excited and the electromagnetic valve 24 is switched, whereby the unload valve 25 is switched to the communication position of the main pressure oil lines 5 and 6. At the same time, the solenoid SOL. 2 is excited and the main circuit solenoid valve 9 is switched to the communication position, so that the servo valve 10 is operated and the actuator 11 is operated in the reverse direction. The angle is switched to the opposite direction, and the pressure oil discharge amount is gradually increased to shift to a constant speed operation. As a result, the forward and backward movements of the main hydraulic cylinders 1 and 2 are switched.
[0017]
Even after the forward and backward movements of the main hydraulic cylinders 1 and 2 are switched, the same control is performed as shown in the time chart of FIG.
[0018]
As described above, in the present invention, based on the signals from the proximity sensors LS1 and LS2 of the main hydraulic cylinders 1 and 2, the main circuit solenoid valve 9 is once neutralized to reduce the pressure oil discharge amount of the main oil pump 4. After that, the discharge amount is set to be zero for a certain time, and the main circuit solenoid valve 9 is switched after receiving the signals (valve switching completion signals) of the proximity sensors LS5 and LS6 of the swing cylinders 12 and 13, Since the pressure oil is supplied to the tilt adjustment actuator 11 to start the discharge of the pressure oil of the main oil pump 4 and the set discharge amount is reached, the operation is shifted to the constant speed operation. It is possible to suppress a large pressure fluctuation that occurs at the time of switching between the two forward and backward movements. The tilt angle command of the main oil pump 4 is given by the pressure reducing valve 21, and the tilt angle increasing speed can be adjusted by the variable throttle valve 20.
[0019]
In the above-described embodiment, the time from when the pressure oil discharge amount of the main oil pump is decreased to zero and the discharge is started again is the combination of the proximity sensors LS1, LS3, LS5 and the proximity sensors LS2, LS4. , LS6 is set in combination, but the functions of the proximity sensors LS3, LS5 and LS4, LS6 may be replaced by a timer that operates on the basis of the signals of the proximity sensors LS1 and LS2. In the embodiment, the suction / discharge valve is shown as a swing valve type, but the same can be applied to a slide valve type as well, and various other modifications are possible without departing from the scope of the present invention. Of course, it can be added.
[0020]
【The invention's effect】
As described above, according to the hydraulic control circuit of the viscous fluid pump of the present invention, the following excellent effects are exhibited.
(1) An actuator having a closed circuit for alternately supplying pressure oil discharged from both tilting main oil pumps to the two main hydraulic cylinders, and for switching the tilting direction of the main oil pump And a servo valve for switching the operating direction of the actuator, and a solenoid valve for a main circuit which is a three-position valve for operating the servo valve, and is accompanied by a forward and backward operation of the two main hydraulic cylinders. In a hydraulic control circuit for a viscous fluid pump having a solenoid valve for a valve circuit that switches a suction / discharge switching valve for switching suction / discharge of viscous fluid, in the vicinity of stroke ends and strokes of the two main hydraulic cylinders respectively a proximity sensor in the end, when the main circuit electromagnetic valve is to be switched to the neutral position by a signal of the proximity sensor in the vicinity of the stroke end To, as the switching signal by the electromagnetic valve for a valve circuit of the proximity sensor of the stroke end is performed, further, by switching completion signal from the suction and discharge switching valve, both in the main circuit electromagnetic valve is switched to the communicating position since the pressure oil to the main hydraulic cylinder along with the tilting direction of the tilting main oil pump is switched is a configuration in which the so that switched to be supplied, detects the stroke position of the main hydraulic cylinder with proximity sensors near the stroke end After that, the discharge amount of the main oil pump is reduced to make the discharge amount zero, and when the main hydraulic cylinder reaches the stroke end near the discharge amount zero, the suction discharge valve is switched by the signal of the proximity sensor at the stroke end, and the suction discharge The main oil pump discharge can be started in response to the valve switching completion signal, so that a large pressure change It is possible to reduce the pulsation can be suppressed, it is possible to exert a closed circuit original effect.
(2) a main hydraulic cylinder signal by a valve circuit electromagnetic valve from the proximity sensor of the stroke-end of switched, solenoid valve for the main circuit by switching completion signal suction and discharge switching valve of the viscous fluid with switched to the communicating position Instead of being switched to supply pressure oil to the main hydraulic cylinder, a timer that operates based on a signal from a proximity sensor near the stroke end of the main hydraulic cylinder is used. By adopting a configuration in which switching is performed so that pressure oil is supplied to the main hydraulic cylinder, the same effect as the item (1) can be obtained, and the discharge amount can be reliably increased after a predetermined time. it can.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an embodiment of a hydraulic control circuit of a viscous fluid pump according to the present invention.
FIG. 2 is a time chart showing operation.
FIG. 3 is a schematic diagram showing an example of a hydraulic control circuit of a conventional viscous fluid pump.
[Explanation of symbols]
1, 2 Main hydraulic cylinder 4 Double tilting main oil pump 9 Main circuit solenoid valve 10 Servo valve 11 Actuator 16 Valve circuit solenoid valves LS1, LS2, LS3, LS4 Proximity sensor

Claims (2)

An actuator for alternately supplying pressure oil discharged from both tilting main oil pumps to the two main hydraulic cylinders, and for switching the tilting direction of the main oil pump; A servo valve for switching the operating direction of the actuator, and a solenoid valve for a main circuit, which is a three-position valve for operating the servo valve, and further includes a viscosity according to the forward and backward operation of the two main hydraulic cylinders. In a hydraulic control circuit for a viscous fluid pump having a solenoid valve for a valve circuit for switching a suction / discharge switching valve for switching between suction and discharge of fluid, in the vicinity of each stroke end and the stroke end of the two main hydraulic cylinders provided a proximity sensor, respectively, as well as to for the main circuit electromagnetic valve is switched to the neutral position by a signal of the proximity sensor in the vicinity of the stroke end, As switching of the solenoid valve for the valve circuit by a signal of the proximity sensor of the stroke end is performed, further, by switching completion signal from the suction and discharge switching valve, both in the main circuit electromagnetic valve is switched to the communicating position tilting hydraulic control circuit of the viscous fluid pump, characterized in that it comprises a main pressure oil to the main hydraulic cylinder along with the tilting direction of the oil pump is switched was so that switched to be supplied configuration. The solenoid valve for the valve circuit is switched by the signal from the proximity sensor at the stroke end of the main hydraulic cylinder, the solenoid valve for the main circuit is switched to the communication position and the main hydraulic cylinder is switched by the switching completion signal of the suction / discharge switching valve for the viscous fluid . Instead of switching to supply pressure oil, a timer that operates based on a signal from a proximity sensor near the stroke end of the main hydraulic cylinder is used to switch the main circuit solenoid valve and the main hydraulic pressure. 2. The hydraulic control circuit for a viscous fluid pump according to claim 1 , wherein switching is performed so as to supply pressure oil to the cylinder .

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