JP3579232B2 - High / low speed switching circuit for earth drill - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hydraulic circuit that switches the rotation speed of an earth drill bucket between high and low.
[0002]
[Prior art]
The earth drill working machine is one in which an earth drill drilling device is installed in a working machine main body based on a crawler crane. The work machine main body includes a traveling body, a revolving body installed rotatably on the traveling body, and a boom mounted on the revolving body so as to be able to move up and down. The earth drill drilling device is composed of a front frame attached to the revolving superstructure of the work machine body, a rotary drive device installed at the tip of the front frame, and a rotary drive device suspended from the boom tip by a winch via a wire rope. It has a kelly bar to which a rotational driving force is transmitted, and an earth drill bucket connected to a tip of the kelly bar. By rotating the kelly bar with the rotary driving device, the earth drill bucket at the tip of the kelly bar is rotated to excavate the ground.
[0003]
In a drilling operation using an earth drill, earth and sand in the earth drill bucket are discharged after excavation, but the earth and sand adheres to the earth drill bucket depending on soil properties. For this reason, it is usually necessary to rotate the earth drill bucket at a high speed after discharging the earth to shake off the attached earth and sand.
[0004]
[Problems to be solved by the invention]
The earth drill rotation drive device is equipped with a hydraulic motor driven by pressure oil from a variable displacement hydraulic pump.Conventionally, the engine speed is maximized, and then the earth drill operation lever is operated to the maximum to operate the hydraulic motor. Is rotated at the maximum speed.
[0005]
The variable displacement hydraulic pump reduces the displacement volume as the discharge pressure becomes higher by so-called horsepower control, and thereby effectively uses the engine output. Such a variable displacement hydraulic pump has a maximum displacement when the pump pressure is equal to or lower than a first predetermined value. When the pump pressure is higher than the first predetermined value, the displacement increases as the pressure increases, and the displacement decreases. This prevents the absorption torque of the hydraulic pump from exceeding the output torque of the engine.
[0006]
The capacity (displacement capacity) of the hydraulic pump and hydraulic motor of the earth drill rotary drive device is determined from various viewpoints, but usually, the earth drill bucket is rotated at a desired rotation speed at a desired drilling torque. It is determined. As a result, the engine speed is maximized when shaking off the earth and sand that has adhered after the earth has been discharged, and the motor speed is limited by the discharge flow rate of the hydraulic pump even if the operating lever for the earth drill is maximally operated, and the bucket speed is slow. The earth and sand may not be able to shake off sufficiently.
[0007]
An object of the present invention is to provide a high / low speed switching circuit for an earth drill that can rotate an earth drill bucket in the air at a higher speed than in the prior art.
[0008]
[Means for Solving the Problems]
The present invention will be described with reference to FIG. 2 showing one embodiment. The present invention relates to variable displacement hydraulic pumps 41A and 41B driven by a prime mover, and grounds rotated by discharge oil of the hydraulic pumps 41A and 41B. The present invention is applied to an earth drill high / low speed switching circuit including variable displacement hydraulic motors 43A and 43B for driving the drill bucket 34. The displacement of the hydraulic pumps 41A and 41B is controlled by horsepower control to switch the rotation speed of the earth drill bucket 34 in at least two stages. When the switching device 51 is switched to the high speed side, the horsepower is controlled. When the maximum displacement of the variable displacement hydraulic pumps 41A and 41B is set to the maximum value and the displacement of the variable displacement motors 43A and 43B is set to the minimum value by control, when the switching device 51 is switched to the low speed side, the horsepower is reduced. By providing the displacement capacity setting means for setting the maximum displacement volume of the variable displacement hydraulic pumps 41A and 41B to the minimum value and the displacement volume of the variable displacement motors 43A and 43B to the maximum value by control, the above-mentioned object is achieved. To achieve.
According to a second aspect of the present invention, in the switching circuit of the first aspect, the displacement setting means includes pump regulators 45A and 45B and motor regulators 46A and 46B, and the switching device 51 includes a hydraulic pump regulator and a hydraulic motor. This is a switch that controls the regulator in conjunction with it.
[0009]
In the section of the means for solving the above problems, description has been made in association with the drawings of the embodiments, but the present invention is not limited to the embodiments.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.
FIG. 1 is a view showing the entire configuration of the earth drill working machine. The earth drill working machine is one in which an earth drill drilling device 30 is installed on a working machine main body 10 based on a crawler crane. The work machine main body 10 includes a traveling body 11, a revolving body 12 rotatably installed on the traveling body 11, and a boom 13 attached to the revolving body 12 so as to be able to move up and down. The earth drill digging device 30 includes a front frame 31 attached to the revolving unit 12, a rotary drive device 32 installed at a tip of the front frame 31, and a winch (not shown) that is hung from the tip of the boom 12 via a wire rope 14. A kelly bar 33 to be lowered and an earth drill bucket 34 connected to a lower end of the kelly bar 33 are provided. The ground drive is excavated by rotating the earth drill bucket 34 by rotating the keriba 33 with the rotary drive device 32.
[0011]
FIG. 2 is a diagram showing a hydraulic circuit of the earth drill working machine. In FIG. 2, pressure oil from variable displacement hydraulic pumps 41A and 41B driven by an engine (not shown) is controlled in direction and flow rate by control valves 42A and 42B, and the rotation direction and rotation speed of variable displacement hydraulic motors 43A and 43B are controlled. Is controlled. The control valves 42A and 42B are switched by pilot hydraulic pressure output from an operating device 44 which is a hydraulic pilot valve. The hydraulic motors 43 </ b> A and 43 </ b> B are driven by the speed reducer 47 to drive the kelly bar 33.
[0012]
In this embodiment, as shown in FIG. 3, the control valve 42A starts to open at the pilot oil pressure P1MPa, and has a maximum opening area at the pilot oil pressure P2MPa. The control valve 42B starts to open at the pilot oil pressure P2MPa, and has a maximum opening area at the pilot oil pressure P3MPa. Therefore, the circuit of FIG. 2 is a so-called merging circuit. When the operating device 44 is operated to the position of L1 in the figure, the pilot oil pressure of the operating device 44 is P2MPa, only the control valve 42A is operated, and the hydraulic motors 43A and 43B rotate at the discharge flow rate from the hydraulic pump 41A. When the operating device 44 is operated to L1 or higher in the figure, the operating device 44 outputs a pressure equal to or higher than the pilot oil pressure P2MPa, the control valve 42B starts to open, and the variable displacement hydraulic motor 43A and 43B rotate. When the operating device 44 is operated to the maximum position L2, the pilot pressure oil becomes P3 MPa, and the control valve 42B has the maximum opening area. At this time, the control valve 42A also has the maximum opening area.
[0013]
The displacement of the variable displacement hydraulic pumps 41A and 41B is controlled by pump regulators 45A and 45B, and the displacement of the variable displacement hydraulic motors 43A and 43B is controlled by motor regulators 46A and 46B, respectively. The pump regulators 45A and 45B respectively increase and decrease the maximum displacement volume of the hydraulic pumps 41A and 41B in two stages (hereinafter, the maximum value is qP1 and the minimum value is qP2) by the pressure oil of the displacement volume switching pilot line 45PC. Switch. In order to control the horsepower, the displacement is controlled in accordance with the pressure oil in the pump pressure line 45PP. This is called PQ control as shown in FIG. 4, and the pump displacement volume, that is, the pump flow rate Q is controlled in accordance with the pump pressure P so that the pump absorption horsepower does not exceed the engine output horsepower. Things. Here, since the maximum displacement volume of the pump is set to two levels, the maximum pump flow rate is limited by Q1 or Q2 in FIG.
[0014]
The motor regulators 46A and 46B switch the displacement volumes of the hydraulic motors 43A and 43B to two levels (hereinafter the maximum value is qM1 and the minimum value is qM2) by the pressure oil of the displacement volume switching pilot pipeline 46PC. .
[0015]
In this embodiment, the maximum displacement of the hydraulic pumps 41A and 41B is set to the minimum value qP2 when the pressure oil in the displacement volume switching pilot lines 45PC and 46PC is the tank pressure, and the displacement of the hydraulic motors 43A and 43B is set. except volume is set to the minimum value qM 2. Conversely, the maximum displacement of the hydraulic pumps 41A, 41B is set to the maximum value qP1 when the pressure oil in the displacement volume switching pilot lines 45PC, 46PC is the pilot pump pressure, and the displacement of the hydraulic motors 43A, 43B is set. It is set to the maximum value qM 1.
[0016]
In FIG. 2, reference numeral 50 denotes a displacement volume command circuit. In this command circuit 50, a displacement volume switching pilot pressure can be switched by a high / low speed switch 51 having two interlocked contacts. As shown, when the switch 51 is open, the solenoid valves 52P and 52M are respectively at the position A. At this time, the maximum pressure specified by the relief valve 54 is applied to the pump regulators 45A and 45B from the pilot pump 53, and the maximum displacement volumes of the hydraulic pumps 41A and 41B are set to the maximum value qP1. On the other hand, the tank pressure is supplied to the motor regulators 46A and 46B, and the displacement volume of the hydraulic motors 43A and 43B is set to the minimum value qM2.
[0017]
When the switch 51 is closed, the solenoid valves 52P and 52M are respectively in the B position. At this time, the tank pressure is supplied to the pump regulators 45A and 45B, and the maximum displacement volumes of the hydraulic pumps 41A and 41B are set to the minimum value qP2. On the other hand, the maximum pressure specified by the relief valve 54 is applied to the motor regulators 46A and 46B from the pilot pump 53, and the displacement volume of the hydraulic motors 43A and 43B is set to the maximum value qM1. FIG. 5 shows the tilt angles of the pump and the motor according to the switching position of the changeover switch 51.
[0018]
The operation of the earth drill high / low speed switching circuit thus configured will be described.
When the high / low speed switch 51 is closed and operated to the low speed (L) side, the solenoid valves 52P and 52M are switched to the low position, tank pressure is supplied to the pump regulators 45A and 45B, and pilot pressure is supplied to the motor regulators 46A and 46B. The maximum pressure specified by the relief valve 54 is applied from the pump 53. Therefore, the maximum displacements of the hydraulic pumps 41A and 41B are set to the minimum value qP2, and the displacements of the hydraulic motors 43A and 43B are set to the maximum value qM1. Therefore, when the operating device 44 is operated to the maximum operating position L2, the hydraulic motors 43A and 43B are operated according to the torque-rotation speed characteristic LC as shown in FIG. In the characteristic LC, the maximum torque is T1 and the maximum rotation speed is N1.
[0019]
On the other hand, when the high / low speed changeover switch 51 is opened and operated to the high speed (H) side, the solenoid valves 52P, 52M are switched to the a position, and the pump regulators 45A, 45B are switched from the pilot pump 53 to the maximum specified by the relief valve 54. Pressure is applied, and tank pressure is supplied to motor regulators 46A and 46B. Therefore, the maximum displacement of the hydraulic pumps 41A and 41B is set to the maximum value qP1, and the displacement of the hydraulic motors 43A and 43B is set to the minimum value qM2. Therefore, when the operating device 44 is operated to the maximum operating position L2, the hydraulic motors 43A and 43B are operated according to the torque-rotation speed characteristic HC as shown in FIG. In the characteristic HC, the maximum torque is T2 (<T1), and the maximum rotation speed is N2 (> N1).
[0020]
As described above, by setting the displacement volumes of both the hydraulic pump and the hydraulic motor as shown in FIG. 5, it is possible to rotate the bucket in the air at a higher speed than before. That is, (the maximum value of the present embodiment) up to displacement volume of qP 1 of conventional hydraulic pump, when the displacement volume of the hydraulic motor and QM1 (maximum value in this embodiment), 6, conventional Can be expressed as PRC. In this characteristic PRC, the motor rotation speed was limited by N3 even though the desired torque T1 could be obtained, and the rotation speed required for shaking off the earth and sand adhering to the bucket after discharging was not obtained. Therefore, the maximum displacement volume of the hydraulic pump can be switched between qP2 and qP1 which is larger than that, so that the maximum displacement volume of the pump is set to the maximum qP1 and the displacement volume of the motor is set to the minimum qM2. 6, the characteristic HC of FIG. 6 can be obtained.
[0021]
Further, in the above embodiment, when the switch 51 is set to the high speed side, the pump maximum displacement is set to the maximum value and the motor displacement is set to the minimum value. When the switch 51 is set to the low speed side, the maximum displacement of the pump is set to the minimum value, and the displacement of the motor is set to the maximum value. Becomes possible. Therefore, during excavation, the changeover switch 51 is switched to the low-speed side, and when the soil is shaken off after the earth is discharged, the switch is merely switched to the high-speed side. The performance is improved. Undesirable operation such as a combination of the maximum pump displacement volume and the minimum motor displacement volume, or the combination of the maximum pump displacement volume and the maximum motor displacement volume. Since the state is prohibited, the operability is good.
[0022]
Note that the two contacts of the changeover switch 51 may be individually operable, and the switching between the pump displacement volume and the motor displacement volume may be performed separately.
[0023]
Further, in the above description, the maximum displacement volume of the hydraulic pump is set in two stages of large and small, and the displacement volume of the hydraulic motor is set in two stages of large and small. Only the maximum displacement volume of the hydraulic pump or the displacement volume of the hydraulic motor may be switched in three or more stages. In addition, the kerry bar is driven by two hydraulic motors, but may be driven by one unit.
[0024]
In the above embodiment, the engine constitutes the prime mover, the command circuit 50 constitutes the switching device, and the regulators 45A, 45B, 46A, 46B and the solenoid valves 52P, 52M constitute the volume setting means.
[0025]
【The invention's effect】
According to the present invention, the maximum displacement volume of the variable displacement hydraulic pump is made switchable in at least two stages, and the displacement volume of the variable displacement hydraulic motor is also switched in at least two stages. By setting the motor displacement volume to the minimum value by the value, the bucket can be rotated at a desired high-speed rotation speed, and the soil attached to the bucket can be effectively shaken off.
In particular, if the pump displacement and the motor displacement are interlocked and set to an optimal operation state as in the second aspect of the invention, the switch can be operated at a high speed when the soil is shaken off after discharging. Only by switching to the side, the earth drill bucket can be rotated at a desired rotation speed, and operability is improved. Undesirable operation such as a combination of the maximum pump displacement volume and the minimum motor displacement volume, or the combination of the maximum pump displacement volume and the maximum motor displacement volume. The state is definitely forbidden.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of an earth drill working machine according to the present invention; FIG. 2 is a circuit diagram showing an embodiment of a high / low speed switching circuit according to the present invention; FIG. FIG. 4 is a diagram for explaining PQ characteristics of a hydraulic pump. FIG. 5 is a diagram for explaining a switching position of a changeover switch and a displacement volume of a pump and a motor. FIG. 6 is a torque of a hydraulic motor. -Diagram showing rotation speed characteristics [Explanation of symbols]
10 Work Machine Body 30 Earth Drill 32 Rotary Drive 33 Keriva 34 Bucket 41A, 41B Variable Displacement Hydraulic Pump 42A, 42B Control Valve 43A, 43B Variable Displacement Hydraulic Motor 45A, 45B Pump Regulator 46A, 46B Motor Regulator 50 Command Circuit 51 High / low speed switch 52P, 52M solenoid valve

Claims (2)

A variable displacement hydraulic pump driven by a prime mover,
A high-low speed switching circuit for an earth drill, comprising: a variable displacement hydraulic motor that is driven by the discharge oil of the hydraulic pump to drive an earth drill bucket;
In the hydraulic pump, displacement is controlled by horsepower control,
A switching device for switching the rotation speed of the earth drill bucket in at least two stages;
When the switching device is switched to the high-speed side, the maximum displacement volume of the variable displacement hydraulic pump by horsepower control is set to a maximum value, the displacement volume of the variable displacement motor is set to a minimum value, and the switching device is operated at a low speed. And a displacement volume setting means for setting the maximum displacement volume of the variable displacement hydraulic pump under horsepower control to a minimum value and the displacement volume of the variable displacement motor to a maximum value. High and low speed switching circuit for earth drills. The switching circuit according to claim 1,
The displacement volume setting means includes a regulator for a pump and a regulator for a motor,
The high / low speed switching circuit for an earth drill, wherein the switching device is a switch that controls the regulator for the hydraulic pump and the regulator for the hydraulic motor in conjunction with each other.

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