JP6621431B2 - Hydraulic drive device for hydraulic excavator - Google Patents

Description

  The present invention relates to a hydraulic drive device for a hydraulic excavator provided with an attachment control device.

  In general, construction machines such as hydraulic excavators can perform various operations by attaching various work attachments in addition to buckets and the like. When the attachment is mounted, it is necessary to set the flow rate and / or pressure required for the actuator of each attachment. This setting usually corresponds to the excavator side.

  In view of this, a hydraulic excavator provided with an attachment control device that switches modes between using the attachment and not using the attachment is disclosed in, for example, Japanese Patent Application Laid-Open No. 2011-163031 (Patent Document 1).

  In this technique, in an attachment control device for a hydraulic excavator having a hydraulic circuit having a plurality of flow control valves including a flow control valve for attachment, either the non-attachment mode or the attachment mode is selected, and the attachment mode is selected. The mode switching means for switching the state of the hydraulic circuit to a state suitable for the use of the attachment actuator, and when the attachment operation means is operated when the attachment mode is not selected by the mode switching means, the attachment actuator And an operation restricting means for restricting the operation.

  In this known technology, in order to prevent the failure of the attachment and other hydraulic equipment and the reduction in the service life when the operator forgets to switch from the excavation mode to the attachment mode and operates the attachment, As a detector, the pump flow rate is limited when the attachment operation amount is detected in the excavation mode.

JP 2011-163031 A

  In Patent Document 1, when the operator forgets to switch from the excavation mode to the attachment mode and operates the attachment, the pump flow rate can be limited. However, when the pump flow rate is limited, the actuator may not be sufficiently protected only by limiting the pump flow rate while the actuator pressure limit value is high.

  Therefore, the problem to be solved by the present invention is to protect the actuator and prevent the actuator from being damaged even when the pump flow rate is limited while the actuator pressure limit value is high.

  In order to solve the above-described problem, an aspect of the present invention provides an engine, at least one hydraulic pump driven by the engine, a plurality of actuators including an attachment actuator, and an operation pilot pressure for attachment. In a hydraulic drive device for a hydraulic excavator provided with an attachment direction control valve for supplying discharged oil to the attachment actuator, a pilot pressure is supplied to the attachment direction control valve to operate the attachment actuator An operation device, an electromagnetic variable relief valve provided in a high-pressure line through which pressure oil is supplied from the attachment direction control valve to the attachment actuator, and a control for changing a set pressure of the electromagnetic variable relief valve A device comprising: The control device includes: a first determination unit that determines whether or not an excavation mode in which a set pressure of the electromagnetic variable relief valve is set to a high pressure compared to a pressure when the attachment actuator is driven; A second determination unit that determines whether or not the attachment actuator is driven by an operating device, the excavation mode is selected by the first determination unit, and the attachment actuator is selected by the second determination unit. When it is determined that the actuator has been driven, the set pressure of the electromagnetic variable relief valve is set so as to be a preset minimum pressure.

  According to one aspect of the present invention, even when the pump flow rate is limited while the actuator pressure limit value is high, the actuator can be protected and the actuator can be prevented from being damaged. Note that problems, configurations, and effects other than those described above will be clarified in the following description of embodiments.

It is a figure showing a hydraulic excavator concerning an embodiment of the present invention. FIG. 2 is a hydraulic circuit diagram showing a hydraulic circuit system of the hydraulic excavator shown in FIG. 1. It is a block diagram which shows the processing content of the controller in the hydraulic circuit shown in FIG. It is a flowchart which shows the control procedure of the controller corresponding to the processing content of FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing an overall configuration of a hydraulic excavator according to an embodiment of the present invention. In FIG. 1, a hydraulic excavator 150 basically includes a traveling body 100, a turning body 101, and a front work machine 102.

  The traveling body 100 includes left and right traveling motors 103 and left and right crawlers 104. The traveling body 100 travels by driving the traveling motor 103 to rotate the crawler 104. The turning body 101 is turned on the traveling body 100 by a turning motor 105.

  The front work machine 102 has a multi-joint structure including a boom 106, an arm 107, and an attachment 108, and is attached so that a predetermined work can be performed on the front side of the revolving structure 101. The boom 106 is attached to the swivel body 101 so as to be able to move up and down, for example, by pin coupling. The arm 107 is rotatably attached to the tip of the boom 106 by, for example, pin coupling.

  The attachment 108 is attached to the tip of the arm 107 by, for example, pin coupling. The boom 106, the arm 107, and the attachment 108 are rotationally driven in a vertical plane by a boom cylinder 109, an arm cylinder 110, and a bucket cylinder 111, respectively. Since the attachment 108 is normally attached instead of the bucket attached to the tip of the arm, it is driven by the bucket cylinder 111.

  The attachment 108 is a breaker in this embodiment. The breaker is for crushing massive objects such as large rocks and concrete lumps, and includes a striking rod made of a steel rod with a sharp tip and a breaker cylinder for driving the striking rod. This breaker cylinder corresponds to an attachment operation cylinder for operating the attachment, and is shown as a first actuator 9a in FIG.

  As the attachment 108, a clam shell, a slope bucket, a trapezoid bucket, a skeleton bucket, a ripper bucket, a bucket crusher, a raw con bucket, a ripper, a hydraulic cutter, a grapple, a lifting magnet and the like are known in addition to a breaker.

  A driver's cab 112 is installed on the front side of the revolving structure 101, and a driving source chamber 113 in which the engine 1 and the hydraulic pump 2 are arranged is installed on the rear. The traveling body 100, the revolving body 101, the boom 106, the arm 107, and the attachment 108 are each driven by an operator operating an operation lever corresponding to the operation of each of the plurality of operation levers in the cab 112. Work becomes possible.

  FIG. 2 is a hydraulic circuit diagram schematically showing an example of a hydraulic circuit system as a hydraulic drive device of the excavator 150 shown in FIG.

  The hydraulic circuit system according to the present embodiment includes an engine 1, a hydraulic pump 2, a pilot pump 3, a main relief valve 4, a hydraulic oil tank 5, a control valve 7, first and second actuators 9a and 9b, a boom 106, and an arm. 107, the operation lever 11 for operating one of the buckets, the pedal 23 for operating the attachment 108, the first and second electromagnetic variable relief valves 14a and 14b, and the controller 20 are basically configured.

  The hydraulic pump 2 and the pilot pump 3 are driven by the engine 1. The suction ports 2 a and 3 a of the hydraulic pump 2 and the pilot pump 3 communicate with the hydraulic oil tank 5. In FIG. 2, each of the hydraulic pump 2 and the pilot pump 3 is single, but may be plural. The discharge port of the hydraulic pump 2 is connected to the control valve 7 via the main oil passage 6.

  The control valve 7 is a center bypass type direction control valve and includes first and second spools 7a and 7b for switching at least a plurality of directions. The first and second spools 7 a and 7 b communicate with the main oil passage 6 at the neutral position, and communicate the discharge pressure of the hydraulic pump 2 to the hydraulic oil tank 5.

  Thus, the control valve 7 is composed of a plurality of switching spools. In the first spool 7a shown as an example, the pilot pressure controlled by the pedal 23 based on the supply oil of the pilot pump 3 is applied to the first or second pilot port 7aa, 7ab, and the spool is displaced. The amount of hydraulic oil supplied from the hydraulic pump 2 to the first actuator 9a is controlled according to the displacement amount. The pilot pressure output by operating the pedal 23 is detected by first and second pressure detection sensors 24a and 24b installed in the first and second pilot pipes 25a and 25b, respectively. Each detected pilot pressure is input to the controller 20. The controller 20 detects the attachment operation amount from the pilot pressure detected by the first and second pressure detection sensors 24a and 24b, and determines whether or not the first actuator 9a is operated from the attachment operation amount. .

  The main oil passage 6 of the first spool 7a supplies pressure oil to the bottom chamber 9aa or the rod chamber 9ab of the first actuator 9a according to the switching position of the first spool 7a. The first actuator 9a expands and contracts according to this supply state, and drives the attachment 108. First and second downstream of the first and second pressure oil supply oil passages 8a and 8b for supplying pressure oil from the first spool 7a to the bottom chamber 9aa and the rod chamber 9ab of the first actuator 9a. First and second electromagnetic variable relief valves 14a and 14b are connected to the return oil passages 8c and 8d. The first and second electromagnetic variable relief valves 14a and 14b communicate with the bottom chamber 9aa and the rod chamber 9ab of the first actuator 9a, respectively, and apply pressure oil when an excessive external force is applied to the first actuator 9a. It has a function of discharging to the hydraulic oil tank 5 side and protecting the first actuator 9a.

  The first electromagnetic variable relief valve 14a is provided on the downstream side of the first pressure oil supply oil passage 8a with respect to the port of the bottom chamber 9aa of the first actuator 9a. The second electromagnetic variable relief valve 14b is provided on the downstream side of the second pressure oil supply oil passage 8b with respect to the port of the rod chamber 9ab of the first actuator 9a. The relief setting pressures of the first and second electromagnetic variable relief valves 14 a and 14 b are electrically set by the controller 20. As described above, the pilot pressure applied to the pilot port of the first spool 7a is input to the controller 20, and the controller 20 knows the state of the pilot pressure applied to the first spool 7a.

  The controller 20 includes a microcomputer system including a central processing unit (CPU), a read only memory (ROM), and a random access memory (RAM). The CPU includes a control unit and a calculation unit. The control unit controls the interpretation of instructions and the flow of program control, and the calculation unit executes calculations. The program is stored in the ROM, and an instruction to be executed (a certain numerical value or a sequence of numerical values) is taken out from the ROM in which the program is placed, expanded in the RAM, and the program is executed. The controller 20 controls the entire excavator 150 and each part. The controller 20 is connected with a monitor 21 having an operation function and a display function as a man-machine interface. For example, an attachment selection display unit and a message display unit are set on the monitor 21, an attachment is selected from the monitor 21, and an attachment setting state is displayed on the monitor 21.

  The second actuator 9b exemplifies one of the boom cylinder 109, the arm cylinder 110, and the bucket cylinder 111 shown in FIG. 1, for example. In the actual machine, the number of actuators and spools corresponding to these cylinders are provided, and each is individually operated by the operation lever 11. The second spool 7b has the same structure as the first spool 7a.

  Further, on the downstream side of the third and fourth pressure oil supply oil passages 8e, 8f connected to the ports of the bottom chamber 9ba and the rod chamber 9bb of the second actuator 9b, the first and second relief valves 15a, 15b is connected, and when an excessive external force is applied to the second actuator 9b, the pressure oil is discharged to the hydraulic oil tank 5 side and has a function of protecting the second actuator 9b. The relief setting pressures of the first and second relief valves 15a and 15b are fixed and set in advance to protect the second actuator 9b. In the actual machine, the second actuator 9b is not replaceable and is fixed, so the fixed relief pressure is set in consideration of the strength and additional pressure of the second actuator 9b.

  The relief pressure of the main relief valve 4 is also fixed and set to a pressure that can protect the entire hydraulic circuit.

  FIG. 3 is a block diagram showing the processing contents of the controller 20. In the figure, the controller 20 is set with a maximum pressure in the excavation mode in which excavation is performed using a bucket and a maximum pressure in using the various attachments described above. In the present embodiment, on the premise of using the first to third attachments, the maximum pressure for these first to third attachments is set as the set pressure. Specifically, as shown in FIG. 3, the set pressure 30 in the excavation mode, the set pressure for the first attachment (ATT1 set pressure) 31a, the set pressure for the second attachment (ATT2 set pressure) 31b, and the third attachment Set pressure (ATT3 set pressure) 31c. Further, although the pressure is higher than the relief pressure of the main relief valve 4, a pressure that does not interfere with the attachment and the hydraulic drive system of the excavator 150 is set as the minimum set pressure 32 regardless of which attachment is used. These set pressures 31a, 31b, and 31c are stored in a nonvolatile RAM mounted on a microcomputer including a CPU, for example.

  The minimum set pressure value can be the minimum pressure set value of the hydraulic circuit, but since the minimum pressure set value of the hydraulic circuit can be defined by the set pressure of the main relief valve 4, in this embodiment, all It is set as the minimum pressure of the set pressure at the time of the attachment mode, and the required minimum pressure limit.

  The controller 20 includes a set pressure 30 in the excavation mode, a first attachment set pressure (ATT1 set pressure) 31a, a second attachment set pressure (ATT2 set pressure) 31b, and a third attachment set pressure (ATT3 set). The first switch function 33a for selecting any one of (pressure) 31c and the second switch function 33b for selecting any one of the minimum set pressures 32 from the first switch function 33a are set in software. The set pressure selected by the first and second switch functions 33a and 33b is input to the first and second relief pressure setting terminals 14a1 and 14b1 of the first and second electromagnetic variable relief valves 14a and 14b, respectively. Then, the relief pressures of the first and second electromagnetic variable relief valves 14a and 14b are set as a valve output (valve opening) proportional to the input signal output.

  In the present embodiment, as shown in FIG. 3, a monitor 21 is connected to the controller 20, and the selection result of the excavation mode or attachment is displayed on the monitor 21.

  In FIG. 3, although it is indicated by an icon, it is also possible to select from a selection screen by characters and set the selected set pressure portion to be displayed in reverse video or colored to clearly indicate the selection state. Alternatively, a rotary analog switch whose selection function is illustrated and a selection result can be displayed on a monitor.

  FIG. 4 is a flowchart showing the attachment control pressure change control procedure executed by the CPU of the controller 20.

  In this control procedure, when control is started, first, operation information of the excavator 150, here, information on which work is performed, that is, whether excavation is performed using a bucket, or an attachment 108 such as a breaker is used. Thus, information on whether or not to execute the function set in the attachment is acquired (step S1). And it is judged from this acquired information whether excavation mode is selected (step S2).

  If the excavation mode is not selected in this determination (step S2: N), the attachment 108 attached to the tip of the arm 107 is not used at a high pressure corresponding to the excavation mode, so the attachment set pressure is changed. Without (step S4), it returns to this main flow and performs the control so far.

  If it is determined in step S2 that the excavation mode is selected (step S2: Y), it is determined whether the attachment operation is on (step S3). Whether or not the attachment operation is turned on is determined by whether or not the pedal 23 for operating the operation valve is depressed, and whether or not the pedal 23 is depressed is determined by the first and second operations for operating the first spool 7a. It can be detected from a change in the pressure state of the pilot lines 25a and 25b. Since the pressures in the first and second pilot pipes 25a and 25b are detected by the first and second pressure detection sensors 24a and 24b as described above, the controller 20 detects the detected first and second pressures. If the controller 20 determines that the attachment operation is turned on from the pressure of the pilot pipes 25a and 25b (step S3: Y), the controller 20 selects the attachment setting pressure to the A side in FIG. 3 by the second switch function 33b. Then, the pressure is changed to the minimum set pressure position (step S5).

  On the other hand, if it is determined from the pressures of the first and second pilot pipelines 25a and 25b that the attachment operation is not turned on (step S3: N), the second switch function 33b selects the B side in FIG. Without changing the attachment set pressure to the minimum set pressure 32, the pressure selected by the first switch function 33a is held.

  Thus, when the work modes such as the excavation mode, the first attachment set pressure 31a, the second attachment set pressure 31b, and the third attachment set pressure 31c are selected, the pressure setting according to each work mode is selected. When the excavation mode is set (step S2: Y) and the attachment operation is on (step S3: Y), the set pressure of the electromagnetic variable relief valve is switched to the minimum set pressure side.

  As a result, even if the operator forgets to switch from the normal excavation mode to the attachment work mode and performs the attachment operation, the attachment and its drive circuit are damaged or broken regardless of the type of attachment. There is no. In other words, when the attachment is operated in the excavation mode in which excavation is performed, if the controller 20 detects the attachment operation amount based on the detection outputs of the first and second pressure detection sensors 24a and 24b, the first and second electromagnetic variable The set pressure of the relief valves 14a and 14b is made lower than the pressure selected in the excavation mode. Specifically, the pressure is changed to the minimum set pressure that is the minimum of the pressures set for each of the various attachments set in advance. At the same time, an operation abnormality such as “Attachment operation was performed in the excavation mode” is displayed on the message portion of the monitor 21 to prompt the operator to return the operation to an appropriate mode. Or inform you that the operation is wrong. As a result, it is possible to prevent the attachment and other hydraulic devices from being damaged, broken down, or shortened.

  For example, depending on the type of attachment such as a crusher or a gripping device, the pressure required for work may be insufficient with the above-mentioned minimum set pressure, and therefore, set on the monitor 21 after changing to the above-mentioned minimum set pressure. A screen capable of selecting a pressure is displayed.

  As described above, according to the present embodiment, the following effects can be obtained.

  (1) In this embodiment, the engine 1, at least one hydraulic pump 2 driven by the engine 1, a plurality of actuators 9a and 9b including an actuator for attachment, and the discharge of the hydraulic pump 2 by the operation pilot pressure for attachment In the hydraulic drive device of the hydraulic excavator 150 having an attachment first spool (direction control valve) 7a for supplying oil to the attachment actuator 9a, a pilot pressure is supplied to the attachment first spool 7a. A pedal (operating device) 23 for operating the attachment actuator 9a, and first and second pipes provided on the high-pressure side pipe through which pressure oil is supplied from the first spool 7a for attachment to the attachment actuator 9a. Electromagnetic relief valve 14a, 14b And a controller (control device) 20 that changes the set pressure of the first and second electromagnetic variable relief valves 14a, 14b. The controller 20 is compared with the pressure when the attachment actuator 9a is driven. A first determination unit (step S2) for determining whether or not the excavation mode for setting the set pressure of the first and second electromagnetic variable relief valves 14a and 14b to a high pressure is selected, and the actuator 23a for attachment by the pedal 23. A second determination unit (step S3) for determining whether or not the vehicle is driven, the excavation mode is selected by the first determination unit (step S2), and the attachment is selected by the second determination unit (step S3) When it is determined that the actuator 9a is driven by the pedal 23, the first and second pressures are set so that the preset minimum pressure is obtained. The set pressure of the electromagnetic variable relief valves 14a and 14b is set.

  With this configuration, even if the operator forgets to switch from the excavation mode to the attachment work mode and operates the attachment, regardless of the type of attachment, the attachment actuator 9a is the attachment and its drive circuit. It is possible to prevent the pressure oil supply circuit and the return circuit from being damaged or damaged. That is, when the attachment 108 is operated in the excavation mode in which excavation is performed, the controller 20 can detect the amount of operation of the attachment and change it to the minimum set pressure that can protect each of the various attachments.

  (2) In the present embodiment, the minimum pressure is a pressure that is the minimum of the pressures set in advance for each of the various attachments. Therefore, a pressure greater than the minimum set pressure 32 is applied to the attachment actuator 9a. No matter what kind of attachment, the damage and failure of the plurality of actuators 9a, 9b, the first and second pressure oil supply oil passages 8a, 8b, and the first and second return oil passages 8c, 8d are eliminated. be able to.

  (3) In the present embodiment, the controller 20 determines that the excavation mode is selected by the first determination unit (step S2: Y), and the attachment actuator 9a is pedaled by the second determination unit. 23, when the non-driving state is determined (step S3: N), the set pressure of the first and second electromagnetic variable relief valves 14a and 14b is set higher than the minimum pressure. (Step S4), it is possible to automatically work in the excavation mode. In the present embodiment, the first determination unit corresponds to the determination process in step S2, and the second determination unit corresponds to the determination process in step S3.

  (4) Moreover, in this embodiment, when it is detected (step S3: Y) that the actuator 9a for attachment is driven in the state where the excavation mode is set (step S2: Y), that fact Since the monitor (display device) 21 for displaying is provided, even if the operator forgets to switch from the normal excavation mode to the attachment work mode and performs the attachment operation, an error message is displayed on the monitor 21. The operator can be prompted to return the operation to the proper mode, or can be informed that the operation is incorrect. As a result, it is possible to prevent the attachment and other hydraulic equipment from being damaged, failed, or shortened.

  (5) Further, in the present embodiment, the operating device includes the first spool 7a of the control valve 7 installed in the hydraulic circuit connected to the attachment actuator 9a, and the first spool 7a of the control valve 7. The first and second pilot pipes 25a and 25b connected to the first and second pilot ports 7aa and 7ab and the pedals installed in the first and second pilot pipes 25a and 25b for controlling the pilot pressure 23. Since it comprised in this way, the breaker which is the attachment 108 can be easily operated by operation of the pedal 23, for example.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention, and all technical matters included in the technical idea described in the claims are included. The subject of the present invention. The above embodiment shows a preferable example, but those skilled in the art can realize various alternatives, modifications, variations, and improvements from the contents disclosed in this specification, These are included in the technical scope described in the appended claims.

1 Engine 2 Hydraulic pump 7 Control valve (direction control valve)
7a 1st spool 7aa 1st pilot port 7ab 2nd pilot port 8a 1st pressure oil supply oil passage (high pressure side pipe line)
8b Second pressure oil supply oil path (high-pressure side pipe line)
9a 1st actuator (actuator for attachment)
9b Second actuator 11 Operation lever 14a First electromagnetic variable relief valve 14b Second electromagnetic variable relief valve 20 Controller (control device)
21 Monitor (display device)
23 Pedal (operating device)
25a First pilot line 25b Second pilot line 108 Attachment 150 Hydraulic excavator

Claims (5)

Engine,
At least one hydraulic pump driven by the engine;
A plurality of actuators including an actuator for attachment;
A hydraulic drive device for a hydraulic excavator, comprising: a directional control valve for attachment that supplies the hydraulic pump discharge oil to the attachment actuator by an operation pilot pressure for attachment;
An operating device for operating the attachment actuator by supplying a pilot pressure to the directional control valve for the attachment;
An electromagnetic variable relief valve provided in a high-pressure line through which pressure oil is supplied from the directional control valve for attachment to the actuator for attachment;
A control device for changing a set pressure of the electromagnetic variable relief valve,
The controller is
A first determination unit that determines whether or not an excavation mode in which a set pressure of the electromagnetic variable relief valve is set to a high pressure is selected as compared to a pressure when the attachment actuator is driven;
A second determination unit that determines whether or not the attachment actuator is driven by the operating device;
When the excavation mode is selected by the first determination unit, and when it is determined by the second determination unit that the actuator for attachment is driven by the operation device, the minimum pressure is set in advance. A hydraulic drive device for a hydraulic excavator, wherein a set pressure of the electromagnetic variable relief valve is set. In the hydraulic drive device of the hydraulic excavator according to claim 1,
The hydraulic drive device for a hydraulic excavator, wherein the minimum pressure is a minimum pressure among pressures preset for each of the various attachments. In the hydraulic drive device of the hydraulic excavator according to claim 1,
The controller is
When the first determination unit determines that the excavation mode is selected, and the second determination unit determines that the attachment actuator is not driven by the operating device, the electromagnetic A hydraulic drive device for a hydraulic excavator, wherein the set pressure of the variable relief valve is set to a set pressure set higher than the minimum pressure. In the hydraulic drive device of the hydraulic excavator according to claim 1,
A hydraulic drive device for a hydraulic excavator, comprising: a display device for displaying when the attachment actuator is driven in a state where the excavation mode is set. The hydraulic drive device for a hydraulic excavator according to claim 2,
The operating device is:
A directional control valve installed in a hydraulic circuit connected to the actuator for attachment;
First and second pilot lines connected to the first and second pilot ports of the directional control valve;
An operation valve that is installed in the first and second pilot lines and controls pilot pressure;
A hydraulic drive device for a hydraulic excavator, comprising: