JPH06323245A - Hydraulic system for hydraulically-driven piston type slurry pump - Google Patents

Abstract

PURPOSE:To provide a hydraulic system which prevents noise and vibration from producing to enable speed control and is capable of operating a slurry pump at high volumetric efficiency. CONSTITUTION:Ten units of hydraulic pumps 1 to 10 are used, and check valves 101, 201,... 1001 are set in the delivery circuits for the hydraulic pumps 1 to 10. Also unloading relief valves 102, 202, 1002 are set in the delivery circuits for all the hydraulic pumps 1 to 10. The operating speed of a slurry pump is determined by the number of hydraulic pumps to be loaded. When the force- feed pistons 34 and 44 and suction and delivery valves 50 of the slurry pump are started and stopped, the hydraulic pumps 1 to 10 are on-loaded and unloaded one by one at a specified interval. Thus the movement of the suction and delivery valve at its start and end is made smooth. In addition, the operating speed of the slurry pump is adjusted by selecting the number of on-load hydraulic pumps among the hydraulic pumps 1 to 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic system of a hydraulically driven piston type slurry pump for pressure-feeding slurry such as dredged soft soil.

[0002]

2. Description of the Related Art In a hydraulically driven piston type concrete pump or slurry pump (collectively referred to as "slurry pump" in the present invention), when a pressure-feeding piston and an intake / discharge valve are sequentially operated in sequence, when switching between them, In particular, the discharge amount of the hydraulic pump is not adjusted, and the hydraulic circuit is switched by simply operating the hydraulic switching valve. As a method of adjusting the operation speed, the shaft rotational speed of the hydraulic pump has been changed, and the variable displacement hydraulic pump has been used to change the pressure oil discharge amount of the hydraulic pump itself. When the suction / discharge valve that switches the suction and discharge of the slurry to the slurry pump is operated, the suction / discharge valve is generally driven with the hydraulic pump discharge amount set according to the operating speed set at that time. Also, especially inhalation
When the change in the operating speed of the discharge valve is a problem, an accumulator was used in the intake / discharge valve drive hydraulic circuit.

Such a conventional hydraulic system in a hydraulically driven piston type slurry pump has the following problems. When the pumping device becomes large in size and becomes a large flow rate hydraulic system, it becomes a serious problem and cannot be tolerated. It was something that ended up.

(1) When the hydraulic circuit is switched to sequentially operate the pressure feeding piston and the suction / discharge valve, the hydraulic switching valve can be switched while the high-speed pressure oil flows in the hydraulic pipeline, so that the high pressure circuit Surge pressure is generated, which causes large noise and vibration.

(2) Similarly, since the driven actuator also reaches the stroke end and stops at a high speed, a large mechanical vibration and noise are generated due to the energy.

(3) If the hydraulic pump is a variable displacement pump for adjusting the operating speed, the cost of the hydraulic pump itself increases, and the control system becomes complicated. In addition, in order to adjust the operating speed, varying the shaft speed of the hydraulic pump requires a complicated device in the case of the electric motor drive system, which results in high cost, and in the case of the engine drive system, There is no problem when the engine capacity is relatively small, but it is not easy to change the rotation speed of a large engine such as several thousand horsepower because there are various problems such as durability and noise and vibration.

Furthermore, in the conventional hydraulic system, even when the intake / discharge valve is switched, since the hydraulic pump oil amount is proportional to the operating speed of the pump, the intake / discharge valve is switched at a low speed operation. The speed becomes slower, the backflow of the pressure-feeding object during switching increases, and the volumetric efficiency of the slurry pump decreases. On the other hand, if the size of the hydraulic cylinder is set so that the switching speed of the intake / discharge valve at low speed operation becomes high, this time, the switching speed of the intake / discharge valve at high speed operation becomes too high, and Durability and noise / vibration increase, which becomes a problem. Also, if an accumulator is installed to increase the switching speed of the intake / discharge valve even at low speeds, additional equipment and a special hydraulic control circuit are required for that, and the device becomes complicated and the cost increases. .

[0008]

SUMMARY OF THE INVENTION The present invention, in a hydraulic system for a hydraulically driven piston type slurry pump, requires a special mechanism for acceleration / deceleration control at the beginning and end of movement of the pressure-feeding piston and the intake / discharge valve of the slurry pump. It is an object of the present invention to provide a hydraulic system that can be realized without any noise and prevents the generation of noise and vibration. Another object of the present invention is to provide a hydraulic system capable of speed control in a hydraulically driven piston type slurry pump without using a special mechanism or the like. Still another object of the present invention is to provide a hydraulic system that operates a slurry pump so as to ensure high volumetric efficiency as a pressure pump regardless of operating speed.

[0009]

In order to solve the above problems, the hydraulic system according to the present invention adopts the following configuration. A large flow rate hydraulic source is configured by connecting multiple hydraulic pumps in parallel. (1) Each hydraulic pump is equipped with an independent unload relief valve. (2) The operation speed of the pressure pump is selected by selecting the number of on-load hydraulic pumps. (3) At the time of starting and ending the movement of the pressure-feeding piston and the suction / discharge valve, the unload relief valve of the selected hydraulic pump is unloaded / onloaded one by one with a fixed time difference to accelerate / decelerate. And (4) When the intake / discharge valve is in operation, a preset number of hydraulic pumps are always on-loaded regardless of the selected operation speed.

[0010]

[Action]

(1) By providing unloading relief valves for all hydraulic pumps individually, it is possible to select unloading / onloading for each hydraulic pump. By selecting the number of onloading hydraulic pumps, Driving speed can be adjusted freely.

(2) At the time of starting and ending the operation of each actuator, by unloading / onloading the unload relief valve of the hydraulic pump one by one with a fixed time difference, the start and end of the operation of each actuator Acceleration / deceleration control is sometimes performed, the pressure of surge pressure generated in the hydraulic circuit is reduced and the pressure of the circuit is also released, the surge pressure generated in the circuit disappears almost completely, and the driven actuator also , It will never reach the stroke end at high speed, and will reach the stroke end in a decelerated state and stop.

(3) When the suction / discharge valve is in operation, a preset number of hydraulic pumps are on-loaded regardless of the operating speed of the selected pumping device, and the suction / discharge valve is always sucked at a constant speed. The discharge valve switches.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A hydraulic system according to the present invention will be specifically described below based on the illustrated embodiments. In FIG. 1, 1
Numerals 10 to 10 represent hydraulic pumps (in this example, 10 hydraulic pumps are shown), 101, 201, 301 ...
Reference numeral 1001 denotes check valves (there are 10) installed in the discharge circuits of the hydraulic pumps 1 to 10, 102, 202, 302 ... 1
002 is an unload relief valve (there are 10), which are solenoid valves 103, 20 installed in the respective vent circuits.
3, 303 ... 1003 (there are 10) are not energized, the hydraulic pump discharge circuit 20 is connected to each of the pipelines 104, 20.
, ... 1004 communicates with the oil tank 24, and when energized, the vent circuit is closed and the unload relief valves 102, 202, ... 1002 function as normal relief valves. Here, the unload relief valve 102 is connected to the secondary side of the above-mentioned check valve 101, but the other unload relief valves 202 to 1002 are provided in the conduit between each hydraulic pump and the check valve. It is connected.

Reference numerals 30 and 40 denote hydraulic cylinders which drive the pressure-feeding pistons 34 and 44 via the piston rods 32 and 42 by the hydraulic pressure acting on the hydraulic pistons 31 and 41. Numerals 33 and 43 are pressure feeding cylinders and pressure feeding pistons 34 and 4
The object 4 is sucked from the chamber 51 by the reciprocating motion of the cylinder 4 in the cylinder, and is pushed out to the pressure-feeding conduit 60 via the suction / discharge valve 50. Reference numerals 35 and 45 are piston position detection sensors, which output an electric signal when the hydraulic pistons 31 and 41 move to the vicinity of the stroke end. Reference numeral 52 denotes a hydraulic cylinder, which swings the suction / discharge valve 50 between two pressure feeding cylinders via a lever 56 to switch between the suction process and the discharge process of the pressure feeding cylinder. Reference numerals 54 and 55 denote piston rod position detection sensors, which output an electric signal near the stroke end when the hydraulic cylinder 52 operates.

FIG. 2 shows a time chart of the embodiment shown in FIG. The horizontal axis of FIG. 2 represents the time axis. In FIG. 2, (1) shows an on-load state of the hydraulic pump, and one step-like step indicates that one hydraulic pump is on-loaded. In FIG. 2, (2) shows the operating states of the piston rod position detection sensors 54, 55 of the hydraulic cylinder 52, and 540 shows the operating state of the sensor 54.
Reference numeral 550 indicates a state in which the sensor 55 is operating. Figure 2
(3) shows the operating state of the piston position detection sensors 35 and 45 of the hydraulic cylinders 30 and 40, where 350 is the operating state of the sensor 35 and 450 is the sensor 45.
Indicates that it is operating.

The uppermost horizontal axis 1 is the intake / discharge valve 5.
0 indicates a period in which the position opposite to the position shown in FIG. 1 is switched to the illustrated state, and II indicates a period in which the hydraulic oil is supplied to the hydraulic cylinder 40 and the hydraulic piston 41 operates in the rightward direction in the drawing.
Indicates a period during which the intake / discharge valve 50 switches from the illustrated position to the opposite position, and IV indicates a period during which the hydraulic oil is supplied to the hydraulic cylinder 30 and the hydraulic piston 31 operates in the right direction in the drawing. Further, according to this figure, as the operating speed of the pressure feeding device (the operating speed of the pressure feeding piston),
Eight hydraulic pumps are selected by operating an operating speed selection switch (not shown). Regardless of this, four hydraulic pumps are on-loaded when the intake / discharge valves are activated.

In the hydraulic system described above,
Eight of the unload relief valves 102 are on-loaded from the higher number side, and the combined pressure oil is supplied to the hydraulic cylinder 40 by the hydraulic pressure switching valve 21 via the discharge pipe 20 (the hydraulic pressure switching valve 21. Coil 21A is energized), the hydraulic piston 41 moves to the right in FIG. 1, and therefore the pressure feeding piston 44 also moves to the right in the pressure feeding cylinder 43 via the piston rod 42. The object to be pressured that has been sucked into the cylinder 4
Push out from 3. The pushed object to be pressure-fed is pressure-fed to the pressure-feeding conduit 60 via the suction / discharge valve 50.

When the hydraulic piston 41 reaches the vicinity of the stroke end, the piston position sensor 45 causes the hydraulic piston 4 to move.
Detecting the approach of 1 and transmitting an electric signal (Fig. 2, (3)
450 rise). The unload relief valve 10 is activated by the signal transmitted from the piston position sensor 45.
2,202,302, ... 1002 is the highest number 1
Place a fixed time (for example, 0.1 second pitch) in sequence one by one, and start unloading to the smaller number (Fig. 2,
(1), C part of II). And finally, when the unload relief valve 102 is unloaded ((A) in Fig. 2, (1), II)
Portion), the pressure in the discharge circuit 20 via the unload relief valve 102 is changed to the pipelines 104, 204, ...
It is opened to the oil tank 24 side via 04 and the pressure in the discharge circuit is released. As described above, the hydraulic piston 41 is rapidly decelerated and reaches the stroke end softly.

After the unload relief valve 102 is unloaded, the coil 21A of the hydraulic pressure switching valve 21 is de-energized and the coil 22B of the hydraulic pressure switching valve 22 is energized. At this time, at the same time, the unload relief valves 102, 202, ...
02 is on-loaded (part D in FIG. 2, (1), III), pressure oil is supplied to the hydraulic cylinder 52, and the intake / discharge valve 50 starts to switch smoothly. After that, the hydraulic pumps are on-loaded up to a preset number (4 in the case of FIG. 2).

When the intake / discharge valve 50 moves to the vicinity of the position opposite to the position shown in FIG. 1, the piston rod position detection sensor 55 is activated, and the signal causes the unload relief valves 102, 202, ... Unloading in order from the larger one, and finally the unloading relief valve 102 unloads to depressurize the hydraulic circuit 20 (portion A in FIG. 2, (1), III). When the pressure release is completed, the coil 22B of the hydraulic pressure switching valve 22 is de-energized, the coil 21B of the hydraulic pressure switching valve 21 is energized, and at the same time, the unload relief valve 102 is sequentially unloaded from the highest unload relief. The valves 102, 202, ... 1002 are on-loaded, and the hydraulic piston 31 starts moving to the right in FIG.

After that, the same operation as described above is performed on the hydraulic cylinder 30 side (FIG. 2, (1), part after IV).
In order to automatically perform the above operations according to the signal from the sensor or the driving speed instruction, if a control device using a microcomputer (for example, a programmable controller) is used, only software is required and special technology is required. Since it can be realized without any explanation, the explanation is omitted.

The present invention has been specifically described above based on the illustrated embodiments, but the present invention is not limited to these embodiments, and the constitution and structure thereof are within the scope of the present invention shown in the claims. It goes without saying that various changes may be added to the. For example, in the above embodiment, the hydraulic pressure switching valves 21 and 22 are described as normal four-way switching valves, but the present invention is not limited to this as long as a similar function can be realized. For example, a logic valve is used. Is also good. The structure of the slurry pump is not limited to the structure shown in FIG. 1, and the point of supplying pressure oil to the hydraulic cylinders 30 and 40 and the suction / discharge valve may be of other types.

[0023]

As described above, according to the hydraulic system of the present invention, the following effects can be obtained. (1) Acceleration / deceleration control can be realized at the beginning and end of movement of the pressure-feeding piston and suction / discharge valve without requiring any special mechanism / control, so movement is smooth and circuit switching is possible. Since the pressure in the circuit can be depressurized at the moment, the occurrence of noise and vibration due to surge pressure in the hydraulic circuit and mechanical collision is prevented. (2) Speed control of a large capacity hydraulic system is possible without requiring any special mechanism or control. (3) Since the operation speed of the suction / discharge valve can be made constant regardless of the pressure feeding speed of the slurry pump, the safety of the equipment is improved and high volumetric efficiency can be secured as a pressure feeding pump regardless of the operating speed. .

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a hydraulic system of a hydraulically driven piston type slurry pump according to an embodiment of the present invention.

2 is a time chart diagram in the hydraulic system shown in FIG. 1, (1) shows an on-load state of the hydraulic pump, (2) shows an operating state of the sensors 54, 55,
(3) shows the operating states of the sensors 35 and 45.

[Explanation of symbols]

1-10 Hydraulic pump 101-1001 Check valve 102-1002 Unload relief valve 103-1003 Solenoid valve which controls unload relief valve 21 Hydraulic switching valve which controls the flow of the hydraulic oil to the hydraulic cylinder which drives a pumping piston 22 Hydraulic switching valve that controls the flow of pressure oil to the hydraulic cylinder that drives the intake / discharge valve 30,40 Hydraulic cylinder that drives the pressure-feeding piston 34,44 Pressure-feeding piston 35,45 Sensor that detects the position of the hydraulic piston 50 Intake・ Discharge valve 52 Hydraulic cylinders for driving intake / discharge valves 54, 55 Sensors for detecting switching of hydraulic cylinders for driving intake / discharge valves

Claims (1)

[Claims] 1. In a hydraulic system of a hydraulically driven piston type slurry pump in which a plurality of hydraulic pumps are connected in parallel to obtain a large flow rate, (1) each is installed in the middle of a discharge circuit of all the hydraulic pumps. Check valve, an unload relief valve installed in the secondary side circuit that has passed through the check valve of one discharge circuit of the hydraulic pump, and the remaining discharge circuits of all the hydraulic pumps. An unload relief valve installed in a circuit between the hydraulic pump discharge port and the check valve, and (2) a pressure-feeding piston of the slurry pump and a suction / switching switch for suctioning and discharging the slurry to the pressure-feeding piston. At the start and end of the operation of the discharge valve, the hydraulic pumps are unloaded or on-loaded one by one with a certain time difference, and (3) the operating speed of the slurry pump is the hydraulic pressure. It is adjusted by selecting the number of on-load pumps. (4) When the suction / discharge valve is operating, a preset number of hydraulic pumps are always on-load regardless of the operating speed of the slurry pump. A hydraulic system for a hydraulically driven piston type slurry pump, which is characterized in that