JP2001207773A - Driving control device for earth auger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving control device for an earth auger capable of excavating work by minimizing a temperature rise in a hydraulic fluid even in a relief state. SOLUTION: In this driving control device for the earth auger for arranging a work device driven by a hydraulic motor on a leader erected in front of a base machine so as to be liftable, the hydraulic motor 21 of the work device 5 is connected via a directional control valve 23 from a variable delivery pump 11. A relief valve 25 and a pressure detector 28 are arranged in a delivery passage of the variable delivery pump 11. When the pressure detector 28 detects the fact of being relief preset pressure, a delivery quantity of the variable delivery pump 11 is controlled in a minimum delivery quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device such as an earth auger for rotating an auger screw by a hydraulic motor.

[0002]

2. Description of the Related Art As shown in FIG. 3, an earth auger is provided so that a working device 5 can be moved up and down by engaging with a guide rail 3 of a reader 2 erected in front of a base machine 1. An auger screw 6 is attached to the lower part of the.

[0003] Then, the auger screw 6 is driven by the working device 5, and the excavator at the lower end of the auger screw 6 is driven underground while rotating to excavate. The excavator is pushed in by providing a pinion in the working device 5 that meshes with a rack provided in the longitudinal direction of the leader 2 and driving the pinion with a hydraulic motor, or winding and lowering the working device 5 with a wire rope. Is performed by using a wire rope for narrowing down.

[0004] The earth auger is provided with a plurality of hydraulic pumps driven by an engine mounted on the base machine 1 for operating various devices constituting the earth auger, including the working device 5 and the pushing device. FIG. 4 shows a part of a hydraulic circuit of a conventional earth auger machine. Two variable discharge pumps 11 and 13 driven by engines are connected to left and right via switching valves 19, 20, 23 and 24, respectively. Pressure oil is supplied to the traveling hydraulic motors 17 and 18, the auger driving hydraulic motor 21, and the auger lifting hydraulic motor 22.

The pressure oil of the variable discharge pumps 11 and 13 is supplied to the hydraulic motors 17, 18, 21 and 22 as well as to the hydraulic motors of the winch. It is omitted here. The operation of the cylinder, such as the support of the leader, the outrigger, and the adjustment of the leader position, is performed by the pressure oil of a separately provided constant discharge type hydraulic pump.

Further, a control hydraulic pump 15 is provided to control the discharge amount of the variable discharge pumps 11, 13 and the rotation of the traveling hydraulic motors 17, 18. Reference numeral 16 denotes a remote control valve which is operated to operate the switching valves 19 and 20.

[0007] In the earth auger, the engine is normally used at a constant speed, the hydraulic motor 21 for driving the auger is operated by setting the variable discharge pump 11 to the maximum discharge amount, and the hydraulic motor 22 for raising and lowering the working device 5 is used. The discharge amount of the variable discharge pump 13 is reduced, and ascending and descending are performed at a constant fine speed so as not to damage the auger screw 6.

In this discharge amount control, the pressure oil of the control pump 15 is appropriately depressurized by a variable pressure reducing valve provided in the discharge amount control device 12, and a swash plate or an oblique shaft attached to the variable discharge pump 11 is controlled. By operating a cylinder that changes the tilt angle.

[0009]

In the excavation work using an earth auger, the load is largely fluctuated due to soil properties and the like, and even if the excavation resistance is increased and the relief valve 25 is operated, it is often temporary. Therefore, excavation work is often continued in the relief state without returning the operation lever of the switching valve 23 to the neutral position. When the operating lever of the switching valve 23 is returned to the neutral position, it takes time before the excavation starts again. Therefore, if the switching valve 23 is set to the neutral position every time the relief valve 25 operates, the work efficiency is poor. is there.

[0010] In the excavation work in the relief state, as long as the excavation resistance does not decrease, the state will continue,
The temperature of the hydraulic oil rises. If the pressure rises sharply, not only the hydraulic oil deteriorates, but also there is a risk that hydraulic equipment such as a hydraulic pump or a hydraulic motor may break due to breakage of the oil film.

[0011] For this reason, when digging work in the relief state, the worker works while paying maximum attention to the rise in oil temperature. As means to prevent the temperature of the hydraulic oil from rising, it is conceivable to increase the capacity of the oil cooler or use an unload valve that returns the hydraulic oil to the oil tank when the oil cooler enters the relief state. When the switching valve is operated to the neutral position, the earth auger which is often used in the state near the maximum output of the engine is not preferable because it leads to a decrease in the engine output, and since the excavation force is lost when the unload valve operates, the excavation power is lost. There is a disadvantage that workability is poor as in the case of

The present invention has been made in view of such a technical background, and an object of the present invention is to provide a drive control device such as an earth auger capable of performing excavation work by minimizing a rise in the temperature of hydraulic oil even in a relief state. The purpose is.

[0013]

In order to achieve the above object, the present invention employs the following means. That is, in a drive control device such as an earth auger provided with a working device driven by a hydraulic motor on a reader erected in front of the base machine so as to be able to move up and down, the hydraulic motor of the working device is switched from a variable discharge pump through a switching valve. Connected, a relief valve and a pressure detector are provided in the discharge flow path of the variable discharge pump, and when the pressure detector detects that the pressure is the relief set pressure, the discharge amount of the variable discharge pump is controlled to the minimum discharge amount. It is characterized by doing so.

The term "earth auger or the like" refers to a construction machine for foundation work having a working device driven by a hydraulic motor on a reader standing in front of a crawler running base machine. Rather, it includes a ground improvement machine that performs excavation and agitation, and an excavator that rotationally drives an excavating tool with a keriba.

Further, the present invention is applied to a system in which a plurality of hydraulic pumps are driven by rotating an engine at a constant speed and a drilling tool is driven by a hydraulic motor. In excavation work such as earth auger, the load fluctuation is often large and the relief set pressure is reached, but when the relief valve is activated, returning the switching valve to the neutral position or using the unload valve is not efficient for excavation work. Therefore, excavation work is often continued even in the relief state.

According to the present invention, in excavation work in the relief state, the excavator is driven with the discharge amount of the variable discharge pump being minimized to prevent the temperature of the hydraulic oil from rising. The control of the discharge amount of the variable discharge pump is such that a swash plate or a cylinder for changing the tilt angle of the oblique shaft attached to the variable discharge pump is operated via a variable pressure reducing valve with pressure oil from a control pump. However, the present invention is not limited to this, and may be, for example, an electrically controlled one.

In the excavation work, when the load is large and the relief set pressure is reached, the discharge amount of the variable discharge pump is controlled to a minimum, but when the load is reduced while the excavation work is continued in this state. The discharge amount of the variable discharge pump is preferably increased stepwise to the maximum discharge amount. Thereby, chattering of the relief valve and howling of the engine can be prevented, and stable control can be performed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an earth auger will be described below with reference to the drawings. The basic hydraulic circuit of the earth auger is the same as that described with reference to FIG.

That is, the two variable discharge pumps 11 and 13 driven by the engines are provided with switching valves 19, 20, 23 and 24.
The hydraulic oil is supplied to the left and right traveling hydraulic motors 17 and 18, the excavation driving hydraulic motor 21 of the working device 5, the auger lifting hydraulic motor 22, and the like.

The switching valves 2 of the hydraulic motors 21 and 22
As for 3, 24, a manual type having an operation lever is used, but the same operation method as the travel switching valves 19, 20 may be used. Further, the discharge amounts of the variable discharge pumps 11 and 13 are configured to be controlled by the hydraulic pressure of a control hydraulic pump 15.

FIG. 1 shows a hydraulic circuit of the hydraulic motor 21 for the working device 5 shown in FIG. 4, and the same components as those used in FIG. 4 are denoted by the same reference numerals. The variable discharge pump 11 connected to the engine is connected to a hydraulic motor 21 of the working device 5 via a manual switching valve 23. In order to control the discharge amount of the variable discharge pump 11, the variable discharge pump 11
It is connected to the.

Further, the variable discharge pump 11 to the switching valve 23
A pressure detector 28 for detecting when the relief set pressure is reached and outputting the same to the discharge amount control device 12 is provided in the flow path to the relief valve. There is provided a neutral detector 27 which detects the return to the position and outputs it to the discharge amount control device 12. In addition, 25 is a relief valve.

The discharge amount of the variable discharge pump 11 is determined by the position of the piston rod of the cylinder which changes the tilt angle of the swash plate or the oblique shaft attached to the variable discharge pump 11,
This is based on the balance between the control hydraulic pressure and the internal spring, and the discharge amount is controlled by changing the control hydraulic pressure with a variable pressure reducing valve.

With this configuration, when the pressure detector 28 detects the relief state during the auger excavation work, the signal is sent to the discharge amount control device 12 and the discharge of the variable discharge pump 11 is performed. The control oil pressure is reduced and sent to the amount control unit so as to minimize the discharge amount, and the tilt angle of the swash plate or the swash axis is changed.

Thus, the discharge amount of the variable discharge pump 11 becomes the minimum discharge amount, and the rotation speed of the hydraulic motor 21 for driving the excavating tool of the working device 5 becomes the minimum. When the excavation resistance is reduced and the relief state is released, that is, when the discharge pressure becomes equal to or lower than the relief set pressure, the discharge amount control device 1 increases the discharge amount of the variable discharge pump 11.
The control hydraulic pressure is increased from 2 and fed, and the tilt angle of the swash plate or the swash axis is changed. In this case, the discharge amount is increased stepwise up to the maximum discharge amount.

As described above, when the relief state is established during the auger excavation, the excavation work is performed with the discharge amount of the variable discharge pump being minimized, so that the oil temperature rise is small, and When the digging resistance decreases, the auger rotation automatically returns to the maximum at the maximum discharge rate.

When the switch valve 23 is operated to the neutral position when the relief state is reached during the auger excavation, the neutral detector 27 detects this and the signal thereof is output to the discharge amount control device 1.
2 to the discharge amount control unit of the variable discharge pump 11 by increasing the control hydraulic pressure so that the discharge amount in the idling state (the set discharge amount when the switching valve 23 is in the neutral position) is increased. The tilt angle of the oblique axis can be changed.

Next, the above operations will be described together with a flowchart shown in FIG. With the start of the drive control device, the discharge pressure of the variable discharge pump 11 is detected (step 110). If the pressure is the relief set pressure, a signal is sent to the discharge amount control device 12 (step 120), and the discharge amount of the variable discharge pump 11 is controlled to a minimum (step 130). If the pressure is not the relief set pressure in step 120, the process proceeds to step 140 and the switching valve 2
When 3 is in the neutral position, that is, when the neutral detector 27 attached to the switching valve 23 for detecting the neutral position detects that it is in the neutral position, a signal is sent to the discharge amount control device 12 and the discharge in the idling state is performed. Controlled to quantity.

On the other hand, when the switching valve 23 is not neutral, the control differs depending on whether or not the variable discharge pump 11 has the maximum discharge amount (step 150). When the discharge amount is the maximum discharge amount, the discharge amount control device 12 maintains the state,
When the discharge amount is not the maximum discharge amount, the discharge amount of the variable discharge pump 11 is increased by one step (step 160), and this control is sequentially repeated to obtain the maximum discharge amount.

[0030]

As described above, the drive control device such as the earth auger of the present invention is provided with the relief valve and the pressure detector in the discharge flow path from the variable discharge pump, and the pressure detector operates at the relief set pressure. When it is detected, the discharge amount of the variable discharge pump is controlled to the minimum discharge amount, so that excavation work can be performed without worrying about a rise in the temperature of the hydraulic oil even in the relief state, and work efficiency is high. In addition, since the ejection amount is increased in a stepwise manner when leaving the relief state, stable control can be performed.

[Brief description of the drawings]

FIG. 1 is a control circuit diagram of a discharge amount of a variable discharge pump as an embodiment of a drive control device such as an earth auger of the present invention.

FIG. 2 is a flowchart for explaining the operation of the apparatus.

FIG. 3 is a schematic side view showing the entire earth auger.

FIG. 4 is a hydraulic circuit diagram of a conventional earth auger.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Base machine 2 ... Leader 3 ... Guide rail 5 ... Working device 6 ... Screw auger 11 ... Variable discharge pump 12 ... Discharge amount control device 13 ... Variable discharge pump 14 ... Discharge amount control device 15 ... Control pump 16 ... Remote control valve 17, 18 ... Hydraulic motor for traveling 19, 20 ... Switching valve for traveling 21 ... Hydraulic motor 22 ... Hydraulic motor 23 ... Switching valve 24 ... Switching valve for raising and lowering 25, 26 ... Relief valve 27 ... Neutral detector 28 ... Pressure Detector

Claims (2)

[Claims] In a drive control device such as an earth auger in which a working device driven by a hydraulic motor is provided on a reader erected in front of a base machine so as to be able to move up and down, a hydraulic motor of the working device is switched from a variable discharge pump to a switching valve. A relief valve and a pressure detector are provided in the discharge flow path of the variable discharge pump, and when the pressure detector detects that the pressure is the relief set pressure, the discharge amount of the variable discharge pump is reduced to the minimum discharge amount. A drive control device for an earth auger or the like, characterized in that the drive control device is controlled in a controlled manner. 2. A neutral detector for detecting that the switching valve is at the neutral position, and when the switching valve is not at the neutral position, the discharge amount of the variable discharge pump is increased stepwise to the maximum discharge amount. A drive control device such as an earth auger according to claim 1.