JPH07180576A - Hydraulic type working machine - Google Patents

Abstract

PURPOSE:To provide a hydraulic type working machine to maintain working efficiency at a high value even when the number of revolutions of a prime mover is reduced. CONSTITUTION:When an ordinary mode is selected by a mode changeover switch 15, the number of revolutions of an engine 1 is maintained at a value responding to the position of a governor lever 13, a solenoid valve 10 is switched to a position A and the delivery pressure of a hydraulic pump 2 is guided to the maximum volume limit cylinder 9 of a regulator 8, and the maximum value of a regulation range of the the displacement volumes of hydraulic pumps 3 and 4 is set to a comparatively low value. When a low noise mode is selected by the mode change-over switch 15, the maximum number of revolutions of an engine 1 is limited to a value lower than the maximum value of the number of revolutions of the engine set by the governor lever 13. Simultaneously, the solenoid valve 10 is switched to a position B and the maximum values of the displacement volumes of the hydraulic pumps 3 and 4 set by a maximum volume limit cylinder 9 are varied to a value higher than an ordinary mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic work machine such as a hydraulic crawler crane, a hydraulic wheel crane, and a rough tele crane.

[0002]

2. Description of the Related Art A variable displacement hydraulic pump is connected to the output shaft of a prime mover such as a diesel engine, and the displacement volume is increased or decreased according to the load of the hydraulic pump while maintaining the maximum number of revolutions of the prime mover during work. A constant pressure horsepower control hydraulic working machine is known. With this type of work machine, the maximum displacement volume of the hydraulic pump is limited so that the discharge rate of the hydraulic pump does not exceed the allowable flow rate of the work machine circuit connected to it even if the prime mover rotates at the maximum permissible speed. To do.

[0003]

When noise is a problem such as nighttime work or city work, it is necessary to lower the rotation speed of the prime mover in the work machine described above. However, regardless of the set value of the prime mover speed, the maximum value of the adjustment range of the displacement volume of the hydraulic pump is kept constant, so if the speed of the prime mover is decreased, the maximum discharge amount of the hydraulic pump also decreases, The operating speed of the working machine driven by the discharged oil becomes slow and the working efficiency deteriorates.

An object of the present invention is to provide a hydraulic working machine which can maintain a high working efficiency even when the rotating speed of the prime mover is reduced and used.

[0005]

When the invention of claim 1 is described in association with FIG. 1 showing an embodiment, the invention of claim 1 is a variable displacement hydraulic pump 3, 4 driven by a prime mover 1, and a hydraulic pump 3. , 4 for adjusting the displacement volume of the displacement volume 8
And a displacement volume limiting means 9 for limiting the maximum value of the displacement volume adjusting range by the displacement volume adjusting means 8, and a prime mover 1.
It is applied to a hydraulic working machine provided with a rotation speed limiting means 12 for limiting the maximum rotation speed. Then, the selection means 1 for selecting either the first work mode or the second work mode.
5 and maximum rotation speed changing means 12 for changing the maximum rotation speed of the prime mover 1 limited by the rotation speed limiting means 12 when the second work mode is selected to a value lower than that when the first work mode is selected. , A maximum displacement volume changing means 10 for changing the maximum value of the displacement volume restricted by the displacement volume limiting means 9 when the second work mode is selected to a value larger than that when the first work mode is selected, 12 is provided to achieve the above-mentioned object. According to the second aspect of the present invention, the maximum rotational speed changing means 12 and the maximum displacement volume are set so that the maximum discharge amounts of the hydraulic pumps 3 and 4 become equal when the first work mode is selected and when the second work mode is selected. The change amounts of the changing means 10 and 12 are set.

[0006]

When the second work mode is selected, the maximum rotation speed of the prime mover 1 is limited to a value lower than that when the first work mode is selected, and noise is reduced. At this time, the maximum value of the adjustment range of the displacement volumes of the hydraulic pumps 3 and 4 is changed to a value larger than that when the first work mode is selected, and the maximum discharge of the hydraulic pumps 3 and 4 accompanying the decrease in the rotation speed of the prime mover 1 is performed. The decrease in volume is offset. In the invention of claim 2, since the maximum discharge amounts of the hydraulic pumps 3 and 4 are equal in both the working mode and the low noise mode, the maximum operating speed of the working machine driven by the discharged oil of the hydraulic pumps 3 and 4 is constant. To be kept.

Incidentally, in the section of means and action for solving the above problems for explaining the constitution of the present invention, the drawings of the embodiments are used for making the present invention easy to understand. It is not limited to.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a hydraulic circuit of a working machine according to the present embodiment, where 1 is an engine and 2 is an output shaft 1a of the engine 1.
Fixed displacement hydraulic pumps 3 and 4 connected to the variable displacement hydraulic pumps 3 and 4 connected to the output shaft 1a through the gear train 5, and 6 a governor (not shown) for increasing or decreasing the rotational speed of the engine 1. Drive motor, 7 is drive motor 6 and engine 1
A push-pull cable for connecting to the governor lever 1b, and a regulator 8 for the hydraulic pumps 3, 4. The regulator 8 has a servo cylinder (not shown) built-in, and the hydraulic pumps 3, 4 are based on the pump discharge pressure and the pilot pressure.
The pump input is controlled to a constant torque by increasing or decreasing the displacement volume of. The regulator 8 includes a maximum volume limiting cylinder 9 that limits the maximum value of the adjustment range of the displacement volumes of the hydraulic pumps 3 and 4.
Is installed. The discharge pressure of the hydraulic pump 2 or the pressure of the tank 11 is introduced into the maximum volume limiting cylinder 9 as a driving pressure according to the switching position of the solenoid valve 10. The regulator 8 is configured such that the higher the driving pressure of the maximum volume limiting cylinder 9, the smaller the maximum value of the adjustment range of the displacement volumes of the hydraulic pumps 3 and 4. In addition, the hydraulic pump 2
4, the gear train 5, and the regulator 8 are integrally housed in a common housing H, and the housing H is directly attached to the engine 1. The oil discharged from the hydraulic pumps 3 and 4 is a hydraulic actuator of various work machines (for example, a winch for boom and elevation or a hydraulic motor that drives a crawler of the undercarriage).
Be led to.

Reference numeral 12 is a control device composed of a microcomputer and its peripheral parts, and is a governor lever 1.
The rotation of the engine 1 is detected by detecting the number of passing teeth of the gears forming the gear train 5, the potentiometer 14 that outputs a signal corresponding to the rotation stop position of No. 3, the mode changeover switch 15 provided in the driver's seat of the working machine, and the like. A rotation speed sensor 16 that outputs a signal corresponding to the number is connected. The control device 12 controls the operation of each part of the working machine based on a predetermined control program. The characteristic part of the present embodiment is that the electromagnetic wave is generated based on the output signals of the potentiometer 14, the mode changeover switch 15 and the rotation speed sensor 16 described above. The valve 10 and the drive motor 6 are controlled according to the procedure shown in FIGS. The governor lever 13 is a well-known one that is provided in the driver's seat of the working machine and is operated by the operator to instruct the set value of the engine speed during work. The mode changeover switch 15 is a lever-type two-position changeover switch, and outputs a signal indicating either the normal mode or the low noise mode according to the changeover position.

When the mode selector switch 15 is operated, the control device 12 starts the mode setting process shown in FIG. In step S1, it is determined whether the low noise mode is currently selected based on the output signal of the mode changeover switch 15. When the low noise mode is determined, the process proceeds to step S2, the solenoid of the solenoid valve 10 is excited, and the solenoid valve 10 is turned on.
Switch to position. In a succeeding step S3, the cutoff speed setting flag of the engine 1 is set to 1 and the mode setting process is ended. When it is determined in step S1 that the mode is not the low noise mode, the process proceeds to step S4, the excitation of the solenoid of the solenoid valve 10 is released, and the solenoid valve 10 is switched to the A position. In a succeeding step S5, the cutoff speed setting flag of the engine 1 is reset to zero.

FIG. 3 shows a control procedure of the engine speed of the engine 1 by the control device 12. The controller 12 controls the operation of the drive motor 6 by executing the illustrated process each time a predetermined control cycle arrives. In the first step S11, the engine speed set by the governor lever 13 and the current engine speed are read by the output signals of the potentiometer 14 and the speed sensor 15. Next step S
At 12, it is determined whether the cutoff speed setting flag is set to 1. When the setting flag 1 is not set, the process proceeds to step S13, and the governor drive motor 6 is driven so that the current engine speed matches the set value of the engine speed by the governor lever 13.
When the setting flag 1 is set in step S12, the process proceeds to step S14, and it is determined whether the set value of the engine speed by the governor lever 13 is the cutoff speed or more. The cut-off speed is lower than the maximum allowable speed of the engine 1, and is given to the control device 12 in advance.

When it is determined in step S14 that the set value of the engine speed is equal to or higher than the cutoff speed, step S1
5, the governor drive motor 6 is driven so that the current rotation speed matches the cutoff rotation speed. On the other hand, when it is determined that the set value of the engine speed is less than the cutoff speed, the process proceeds to step S13.

According to this embodiment, the mode changeover switch 1
Depending on whether the normal mode or the low noise mode is selected by 5, the maximum value of the adjustment range of the displacement volumes of the hydraulic pumps 3, 4 and the maximum rotation speed of the engine 1 are controlled as follows. (1) Exclusion volume of hydraulic pumps 3 and 4 When the normal mode is selected, the solenoid valve 10 is processed in step S4.
Becomes the position A, and the discharge pressure of the hydraulic pump 2 is guided to the maximum volume limiting cylinder 9 of the regulator 8. On the other hand, when the low noise mode is selected, the solenoid valve 10 is turned on by the process of step S2.
The position is reached, and the drive pressure of the maximum volume limiting cylinder 9 becomes equal to the tank pressure. Maximum volume limit cylinder 9 as described above
Since the maximum value of the adjustment range of the displacement volumes of the hydraulic pumps 3 and 4 becomes smaller as the driving pressure of the hydraulic pump becomes higher, the maximum volume limiting cylinder 9 is selected when the low noise mode is selected than when the normal mode is selected.
The maximum value of the displacement volume of the hydraulic pumps 3 and 4 which is limited by is increased.

(2) Engine speed When the normal mode is selected, the cutoff speed setting flag is reset to 0 by the process of step S5, and step S1
The rotation speed of the engine 1 is controlled according to the set value by the governor lever 13 by the processing of S2 and S13. Therefore,
The maximum rotation speed of the engine 1 is equal to the maximum value of the rotation speed that can be set by the governor lever 13. On the other hand, when the low noise mode is selected, the cutoff rotation speed setting flag 1 is set in the processing of step S3. Therefore, when the setting value of the rotation speed by the governor lever 13 becomes equal to or more than the cutoff rotation speed, the processing of steps S14 and S15 is performed. The rotation speed of the engine 1 is fixed to the cutoff rotation speed. Therefore, in the low noise mode, the maximum rotation speed of the engine 1 becomes lower than in the normal mode.

As is apparent from the above, in the present embodiment, the maximum rotation speed of the engine 1 is changed to a value lower than that in the normal mode by selecting the low noise mode, and at the same time, the displacement volumes of the hydraulic pumps 3 and 4 are maximized. Since the value is changed to a value larger than that in the normal mode, the reduction of the maximum discharge amount of the hydraulic pumps 3, 4 due to the reduction of the maximum engine speed is suppressed while reducing the noise, and the discharge of the hydraulic pumps 3, 4 is suppressed. It is possible to prevent the maximum speed of the hydraulic actuator driven by oil from decreasing and maintain high work efficiency.

FIG. 4 shows the relationship between the discharge pressure P and the discharge amount Q of the hydraulic pumps 3 and 4 when the engine 1 is rotated at the maximum rotation speed in the normal mode and the low noise mode. In both the normal mode and the low noise mode, the maximum pressure P of the circuit connected to the hydraulic pumps 3 and 4
When max is equal to the discharge pressure P of the hydraulic pumps 3, 4, the displacement volume of the hydraulic pumps 3, 4 becomes the minimum value of the adjustment range by the regulator 8. When the discharge pressure P becomes lower than Pmax, the displacement volumes of the hydraulic pumps 3 and 4 increase, and the discharge amount Q increases accordingly. When the displacement volume reaches the maximum value of the adjustment range by the regulator 8, the maximum discharge amount Qma
x is obtained. The maximum discharge amount Qmax is set in a range in which the operating speed of the hydraulic actuator driven by the discharge oil of the hydraulic pumps 3 and 4 does not exceed the allowable maximum speed in order to increase the work implement speed and the work efficiency in the no-load state. Set as high as possible.

Assuming that the maximum displacement volumes of the hydraulic pumps 3 and 4 are the same in the normal mode and the low noise mode, the maximum discharge amount in the low noise mode is the maximum rotation speed of the engine 1 in both modes. Is decreased by an amount ΔQ corresponding to the difference of Qp to Qp, and the operation speed of the hydraulic actuator becomes slow. In this embodiment, since the maximum displacement volume in the low noise mode is changed to a value larger than that in the normal mode, the maximum discharge amount in the low noise mode is larger than Qp by an amount corresponding to the change amount. Also grows. When the maximum rotation speed of the engine 1 in the normal mode is N1, the maximum displacement volume is q1, the cutoff rotation speed in the low noise mode is N2 (<N1), and the maximum displacement volume is q2,

[Equation 1] If q2 = q1 · N1 / N2 is set, the maximum discharge amount in the work mode and the low noise mode is made equal to Qmax, and the maximum speed of the hydraulic actuator driven by the discharge oil of the hydraulic pumps 3 and 4 is constant. Can be kept at In this case, the working machine is driven at exactly the same speed in the no-load state regardless of the mode, and the reduction in working efficiency is minimized.

In this embodiment, the case where the displacement volumes of the two variable displacement hydraulic pumps 3 and 4 are controlled by the common regulator 8 is shown. However, the present invention uses a single variable displacement hydraulic pump. It can also be applied to the case where different regulators are used for a plurality of hydraulic pumps. The mode changeover switch 15 is not limited to the lever type, and various changes such as a push button type switch can be made. An adjuster for adjusting the cutoff speed of the engine 1 when the low noise mode is selected may be provided. In this case, the change amount of the maximum value of the displacement volume may be adjusted according to the set value of the cutoff rotation speed.

In the above embodiment, the engine 1 is the prime mover, the hydraulic pumps 3 and 4 are the variable displacement hydraulic pumps, the regulator 8 is the displacement volume adjusting means, and the maximum volume limiting cylinder 9 is the displacement volume limiting means. , Mode selector switch 1
5 is the selecting means, the control device 12 is the rotation speed limiting means and the maximum rotation speed changing means, the solenoid valve 10 and the control device 12
Constitutes the maximum displacement volume changing means, and the normal mode is the first
The work mode and the low noise mode correspond to the second work mode.

[0020]

As described above, according to the present invention,
When the second work mode is selected, the maximum rotation speed of the prime mover is limited to a value smaller than that when the first work mode is selected, and the maximum value of the displacement range of the displacement of the hydraulic pump is set to the first work mode. Since the value is changed to a value that is larger than when selected, the maximum speed of the prime mover is set as high as possible in the first work mode to effectively use the output of the prime mover, while in the second work mode the speed of the prime mover is changed. By lowering the noise to reduce the noise, it is possible to prevent the operating speed of the working machine driven by the discharge oil of the hydraulic pump from decreasing and to maintain the working efficiency high. According to the invention of claim 2, the maximum discharge amount of the hydraulic pump is constant regardless of the working mode, so that the maximum operating speed of the working machine driven by the discharge oil of the hydraulic pump is kept constant.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a flowchart showing a mode setting process in the control device of FIG.

3 is a flow chart showing an engine speed setting process in the control device of FIG. 1. FIG.

FIG. 4 is a diagram showing a relationship between a discharge pressure and a discharge amount of a hydraulic pump in a normal mode and a low noise mode of the working machine of FIG. 1.

[Explanation of symbols]

 1 Engine 3, 4 Variable displacement hydraulic pump 6 Governor drive motor 8 Regulator 9 Maximum volume limit cylinder 10 Solenoid valve 12 Controller 13 Governor lever 15 Mode changeover switch

Claims (2)

[Claims] 1. A variable displacement hydraulic pump driven by a prime mover, a displacement volume adjusting means for adjusting the displacement volume of the hydraulic pump, and a maximum displacement range of the displacement volume by the displacement volume adjusting means. In a hydraulic working machine comprising a displacement volume limiting means for limiting a value and a rotation speed limiting means for limiting the maximum rotation speed of the prime mover, one of a first work mode and a second work mode is set. When the second working mode is selected, the selecting unit that selects the maximum rotation speed of the prime mover that is limited by the rotation speed limiting unit is the first rotation speed.
The maximum rotation speed changing means for changing the value to a value lower than that when the work mode is selected, and the maximum value of the displacement volume limited by the displacement volume limiting means when the second work mode is selected. 1
And a maximum displacement volume changing means for changing the value to a value larger than that when the work mode is selected. 2. The hydraulic working machine according to claim 1, wherein the maximum discharge amount of the hydraulic pump is equalized when the first work mode is selected and when the second work mode is selected. A hydraulic working machine characterized in that the changing amounts of the rotation speed changing means and the maximum displacement volume changing means are set.