AUTOMATIC VIBRATION METHOD AND APPARATUS FOR HYDRAULIC EXCAVATOR

Abstract: This invention relates to an automatic vibration method and apparatus for a hydraulic excavator which is used for a hydraulic excavator having a work machine consisting of booms, arms and bucket and applies suitable vibration to the work machine in order to reduce excavation resistance despite the change of nature of the soil and diversified tasks and to conduct efficiently the excavation work. Particularly in the present invention, an operation mode (Bo, A, Bu, Sk) and vibration mode (L, M, S) are set in advance in accordance with nature of the soil and an operation pattern, and suitable vibration is automatically generated as an automatic vibration mode. The operation load of a work machine lever is included with the vibration described above. For this reason, even in a simple and delicate repetition work such as the rolling work, the sieving work or the excavation work with vibration applied to the bucket, the work can be executed easily and uniformly without imparting a great deal of load and fatigue to the operator, and work efficiency can be improved drastically.

Description: The present invention relates to an automatic vibration method and device for use in a hydraulic excavator with working parts consisting of a boom, an arm and a bucket to apply adequate vibrations to the working parts and thereby achieve effective drilling with reduced resistance in various types of operations or even when the soil is changed. From WO 91/05113 a hydraulic driving machine is known which is capable of performing repeated operations automatically and which is also capable of reducing a correction operation by correcting an automatic operation through intervening a lever operation during automatic operation. Further there is a vibration method for a reciprocating motion of a cylinder in response to a signal from directional control circuit is known from JP-A-59-31537. Recent progress of the electronic technologies is remarkable. In the operation of cylinders for the working parts of construction equipment, electronic hydraulic control has replaced the mechanical control. In the structure shown in, for example, Fig. 5, a converter 52 converts the control input of a lever 51 operated by the operator into an electric signal, and inputs it to a controller 53. The controller 53 outputs an electric signal proportional to the control input to a solenoid 55 or 56 of an electro-magnetic proportional valve 54. The electromagnetic proportional valve 54 is opened proportionally to the electric signal, and an amount of oil proportional to the amount of the opening is supplied to a working part cylinder 61 via pipes 58 and 59 or a pipe 60. The discharged oil from the working part cylinder 61 is returned to a tank 63 via a pipe 62. However, the above-described conventional technique is performed manually, and therefore simple and minute repeated operations of the hydraulic excavator, such as pressure-shifting or sifting work, makes the operator exhausted. Also, in pressure-shifting, sifting or drilling carried out while the bucket is vibrated in order to increase the drilling force, the electro-magnetic proportional valve 54 must be activated at a very high speed. However, in an electro-magnetic proportional valve having a large capacity, the force of inertia is large and there is a limit to increasing the switching speed. Consequently, it is impossible to apply adequate vibration to the bucket to cope with changes in the operation form or soil. In view of the aforementioned problems, an object of the present invention is to provide an automatic vibration method and device for a hydraulic excavator which are capable of effective drilling by reducing the resistance to cope with various types or operations or changes in the soil. Disclosure of Invention The present invention provides an automatic vibration method for a hydraulic excavator which comprises a working mode in which a vibration signal for at least one working part selected from a boom, an arm and a bucket is selected from a memory according to an operation form, a vibration mode in which an amplitude and a frequency of the selected vibration signal are selected from the memory according to the operation form, and an automatic vibration mode in which the vibration signal selected by the working mode and the vibration mode is output to an electronic hydraulic valve of an actuator of the working part. An operation signal corresponding to a control input of a working part lever is added to the vibration signal selected from the memory by the working mode and the vibration mode. The present invention also provides an automatic vibration device for a hydraulic excavator which comprises a working mode switch for selecting a vibration signal for at least one working part selected from a boom, an arm and a bucket from a memory according to an operation form, a vibration mode switch for selecting an amplitude and a frequency of the selected vibration signal from the memory according to the operation form, and an automatic vibration mode switch for outputting the vibration signal selected by the working mode and the vibration mode to an electronic hydraulic valve of an actuator of the working part. The automatic vibration device for the hydraulic excavator further includes an addition circuit for adding an operation signal corresponding to a control input of a working part lever to the vibration signal selected from the memory by the working mode switch and the vibration mode switch. In the above-described structure, when the operator selects the vibration signal for at least one working part from the memory using the working mode switch, the amplitude and frequency of the vibration signal from the memory using the vibration mode switch the automatic vibration mode using the automatic vibration mode switch, the vibration signal is input to the electronic hydraulic valve of the working part actuator to automatically vibrate the selected working part at the selected amplitude and frequency. Furthermore, since the operation signal corresponding to the control input of the working part lever which is operated by the operator is added to the vibration signal by the addition circuit, the selected working part can be vibrated similarly using the obtained vibration signal. Thus, adequate vibration can be automatically generated by setting the working mode and vibration mode according to the soil or operation form beforehand and by setting the automatic vibration mode. Furthermore, since the control input of the working part lever can be added to the vibration, simple and minute repeated operations, such as pressure-shifting, sifting or drilling conducted while the bucket is vibrated, can be performed readily and uniformly without exhausting the operator, and workability can thus be greatly improved. Brief Description of the Drawings Fig. 1 is an electric and hydraulic circuit diagram of an automatic vibrating device for a working part according to an embodiment of the present invention; Fig. 2 is a flowchart of an automatic vibrating method for a working part according to an embodiment of the present invention; Fig. 3 illustrates an automation controller shown in Fig. 1; Fig.4 illustrates the operation of an actuator according to the embodiment of the present invention; and Fig. 5 is a conventional electric and hydraulic circuit diagram. Best Mode for Carrying Out the Invention Fig. 1 is an electric and hydraulic circuit diagram of a working part automatic vibrating device according to an embodiment of the present invention. In Fig. 1, reference characters 1a and 1b denote right and left working parts levers. 2a, 2b and 2c denote devices for converting the control inputs of the working parts levers 1a and 1b into electrical signals. 3 denotes an automation controller with a vibration mode/work mode memory to be selected by electric signals respectively designated by a vibration mode switch 4 and a work mode switch 5 incorporated therein. When an automatic vibration mode switch 6 is turned off after the vibration mode/work mode memory has been selected, a vibration signal of the selected vibration mode/work mode is input to an electronic controller 7. That is, in the vibration mode switch 4, either the L mode: large amplitude/low frequency, the M mode: intermediate amplitude/intermediate frequency or the S mode: small amplitude/high frequency is selected from the memory as the vibration mode. In the work mode switch 5, the Bo mode: boom vibrated, the A mode: arm vibrated, the Bu mode: bucket vibrated or the Sk mode: arm and bucket vibrated simultaneously (hereinafter referred to as a skeleton vibration) is selected from the memory as the work mode. The vibration signals of the selected vibration mode/work mode are output from the automation controller to the electronic controller 7 in the form of pulsed voltage signals J Bo , J A , J Bu and J Sk . In the controller 7, for example, the boom voltage signal J Bo and the command flow rate to a boom cylinder 15 have a relation shown in Fig. 7b. The command flow rate of the boom voltage signal changes with time in the manner shown in Fig. 7c. The command flow rate of the boom voltage signal and a current signal have a relation shown in Fig. 7d. Thus, the boom voltage signal J Bo is output from the controller 7 to a solenoid 8 or 9 of electronic hydraulic valves 10 and 11 or 12 and 13 in the form of current signals 7e and 7f. The thus-arranged automatic vibration device is operated in the manner described blow. When the automatic vibration mode switch 6 is turned off and the work mode switch 5 is set to the Bo mode while the vibration mode switch 4 is set to the L mode, the controller 3 outputs a pulsed voltage signal such as that indicated by 7a to the electronic controller 7 as the boom voltage signal J Bo . The controller 7 converts the voltage signal J Bo into a boom raising current signal or a boom lowering current signal indicated by 7e and 7f and outputs the same to the solenoid 8 or 9 of the electronic hydraulic valves 10 and 11 or 12 and 13. When the boom raising current signal 7e is input to the solenoid 8, poppet valves 10 and 11 are opened according to the signal, and the amount of pressure oil corresponding to the amount of opening of the poppet valves is discharged from a hydraulic pump 14 and is supplied to a bottom chamber of the boom cylinder 15, moving a piston rod in the direction indicated by an arrow P. Concurrently with this, the pressure oil discharged from a rod chamber returns to a tank 16. When the boom lowering current signal 7f is input from the electronic controller 7 to the solenoid 9, poppet valves 12 and 13 are opened according to the signal, and the amount of pressure oil discharged from the hydraulic pump 14 according to the amount of opening is supplied to the boom cylinder 15 while the pressure oil is discharged to the tank 16, moving the piston rod in the direction indicated by an arrow Q. Thus, the piston rod of the boom cylinder 15 is moved back and forth by P and Q directions in the L mode. Since there are four work modes Bo, A, Bu and Sk and three vibration modes L, M and S, 12 types of operation forms can be carried out in total. In Fig. 1, only the operation of the boom cylinder 15 have been illustrated. The other working cylinders are operated in the same manner, and description thereof is omitted. Fig. 2 is a flowchart of the automatic vibration method according to the embodiment of the present invention. After the automatic vibration method has been started, the automatic vibration mode switch 6 is turned off in step S1. If the working mode switch 5 is set to the Bo mode in step S2, the process goes to step S3. If the vibration mode switch 4 is set to the L mode in step S3, the vibration signal memory for the Bo mode and L mode is written out in step S4. The vibration signal read out from the memory is input to the electronic controller 7 as the boom voltage signal J Bo . If the operator operates the working part lever 1a, the control input of the lever la is converted into a boom lever operation signal I Bo by the electric signal converting device 2a, and the converted signal I Bo is added to the vibration signal memory in step S5. The obtained vibration signal is input to the electronic controller 7 as a pulsed boom voltage signal K Bo . The electronic controller 7 converts the boom voltage signal K Bo into a current signal and inputs it to the solenoid 8 or 9. If the working mode switch 5 is set to the A mode in step S2 shown in Fig. 2, the process proceeds from steps S1 and S2 to step S9, and an arm voltage signal J A or K A is output via the process enclosed by a frame indicated by *A which contains the similar step to that of the L mode described in a frame indicated by *Bo to perform vibration of the arm in the same manner as the boom. If the working mode switch 5 is set to the Bu mode, the process goes from steps S1, S2 and S9 to step S10, and a bucket voltage signal J Bu or K Bu is output via the process enclosed by a frame l'indicated by *Bu which contains the similar step to that of the L mode described in the frame indicated by Bo to perform vibration of the bucket. If the working mode switch 5 is set to the Sk mode, the process passes through step S1, S2, S9, S10 and a skeleton voltage signal J Sk or K Sk is output via the process enclosed by a frame indicated by *Sk which contains the similar step to that of the L mode described in the frame indicated by *Bo to perform skeleton vibration. Skeleton work originating from sifting the soil in a skeleton-shaped bucket indicates the opeation in which both the arm and the bucket are activated at the same time. Fig. 3 illustrates the automation controller 3 shown in Fig. 1 in detail. When the automatic vibration mode switch 6 is turned on, a switch 18 is attracted to a magnet 17 to provide the manual mode. Turning off of the automatic vibration mode switch 6 makes the switch 18 separated from the magnet 17 and thus provides the automatic vibration mode in which the vibration signal corresponding to the modes set by the vibration mode switch 4 and the working mode switch 5 is output from a memory 19. The output vibration signal is input to the electronic controller 7 as the pulsed voltage signal J. If the operator operates the working part lever 1a or 1b, the control input of the lever is converted into an electric signal by the electric signal converter 2a, 2b or 2c, and the converted electric signal is added to the vibration signal. The vibration signal obtained by an addition circuit as a result of addition is input to the electronic controller 7 as the pulsed voltage signal K. Fig. 4 illustrates the operation of an actuator according to the embodiment of the present invention. The ordinate axis represents the stroke (amplitude) of the actuator, and the abscissa axis represents the time (frequency). While the working part lever 1a or 1b is not operated, the actuator is pulse vibrating at a fixed amplitude (e) and a fixed frequency. Once the working part lever 1a or 1b is operated, the reference level of the pulses varies with the control input of the levers added thereto. In the case of the actuator for the boom cylinder, when raising and lowering operations of the boom are performed, the boom rises and lowers with the same amplitude (e) at a longer period. Industrial Applicability The automatic vibration method and device according to the present invention are employed in a hydraulic excavator with working parts consisting of a boom, arm and bucket and are particularly advantageous in pressure-shifting, sifting or drilling carried out while the bucket is vibrated in order to increase the drilling force.

Claims: An automatic vibration method for a hydraulic excavator with working parts consisting of a boom, an arm and a bucket, said method comprising: a working mode in which a vibration signal for the at least one working part selected from the boom, the arm and the bucket is selected from a memory according to an operation form; a vibration mode in which an amplitude and a frequency of the selected vibration signal are selected from the memory according to the operation form; and an automatic vibration mode in which the vibration signal selected by the working mode and the vibration mode is output to an electronic hydraulic valve of an actuator of the working part, wherein an operation signal corresponding to a control input of a working part lever is added to the vibration signal selected from the memory by the working mode and the vibration mode. An automatic vibration device for a hydraulic excavator with working parts consisting of a boom, an arm and a bucket, comprising: a working mode switch for selecting a vibration signal for the at least one working part selected from the boom, the arm and the bucket from a memory according to an operation form; a vibration mode switch for selecting an amplitude and a frequency of the selected vibration signal from the memory according to the operation form; and an automatic vibration mode switch for outputting the vibration signal selected by the working mode and the vibration mode to an electronic hydraulic valve of an actuator of the working part, further comprising an addition circuit for adding an operation signal corresponding to a control input of a working part lever to the vibration signal selected from the memory by the working mode switch and the vibration mode switch.

Inventors: ONODA TAKUMI, TAKAMURA FUJITOSHI, ONODA, TAKUMI, TAKAMURA, FUJITOSHI
Applicants: KOMATSU MFG CO LTD, KABUSHIKI KAISHA KOMATSU SEISAKUSHO
Application year: 1990
Main classification: E02F3
IPC codes: E02F9, E02F3