JP2005248468A - Hydraulic control circuit for rotary work machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide hydraulic control circuit for a rotary work machine, which prevents occurrence of cavitation or peak pressure in a hydraulic circuit even if a lock lever is unexpectedly operated or an operating direction of the work machine is inverted. <P>SOLUTION: The hydraulic control circuit is formed of a control valve (17) for controlling at least one hydraulic motor (19) for driving the rotary work machine (21), pilot operating valves (11, 12) for controlling the opening of the control valve (17), a lock valve (13) for switching between supply and interruption of pressure oil from a hydraulic source to the control valve (17) or pilot pressure of the pilot operating valves (11, 12), a work machine locking detection sensor (34) for detecting an operating location of the lock lever (5) for selectively switching the lock valve (13), and a controller (30) for issuing a command for progressively decreasing the opening of the control valve (17) at a predetermined rate or less to close the control valve, to the pilot operating valves (11, 12), upon detection of input of a locking signal from the sensor (34), and issuing a command for closing the locking valve (13) after the lapse of a predetermined time period. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a hydraulic control circuit that controls rotation / stop of a rotary working machine such as a rotary excavator or a rotary crusher.

  Conventionally, in a working machine that drives a working vehicle or drives a working machine such as a rotary excavator or a rotary crusher with a hydraulic motor, a control valve that controls the inflow amount and direction of pressure oil to the hydraulic motor has been provided. In some cases, the operation is controlled via a controller by operating an electric lever, and the rotation speed of the hydraulic motor is normally controlled in accordance with the operation amount of the electric lever. For example, Patent Document 1 discloses that during this control, the hydraulic circuit pressure is raised and lowered and the pump discharge amount is increased and decreased by operating the control valve, and the operation time and the hydraulic circuit pressure is raised and lowered accordingly and the pump discharge amount is increased and decreased. The modulation pattern is set to limit the maximum operating speed of the control valve (maximum change speed of the operation signal) so that the ratio of the Modulation control that absorbs the shock that occurs when the control valve and pump are operated by operating the control valve and pump variable device so that it does not move faster than the set time (modulation pattern) And further prevent cavitation that occurs when the pump is in operation.

Japanese Patent No. 2509311 (page 3, FIG. 2)

  According to the conventional hydraulic control circuit described above, when the circuit pressure rises and falls at a constant rate according to the operation time, the control valve and the pump variable device are operated so as not to move faster than the modulation pattern. It is possible to absorb the shock generated when the control valve and the pump are operated, and to prevent the cavitation generated when the pump is operated.

  On the other hand, in a construction machine such as a bulldozer or a hydraulic excavator, on the left or right side of the driver's seat, the main pressure to the control valve of the traveling or working machine (hereinafter collectively referred to as working machine) (ie, working machine) It is common to provide a work implement lock lever that can shut off the operation pilot pressure to the control valve or the input hydraulic pressure from the pressure source. Based on the ON / OFF operation signal of the work implement lock lever, the control valve's main pressure on / off valve or the control valve's operation pilot pressure on / off valve is operated. When the operator leaves the driver's seat When the work implement lock lever is turned on (lock side), the on / off valve is shut off to disable the operation of the control valve, thereby preventing the operation of the work implement unexpected by the operator.

  However, in the conventional hydraulic control circuit, when the lock lever is turned on (on the lock side) during operation of the work machine, the pilot valve operating pilot or the control valve operating pilot is operated during the rotation of the hydraulic motor. Since the pressure on / off valve is suddenly forcibly cut off, cavitation occurs in the hydraulic circuit of the hydraulic motor, or peak pressure occurs in the hydraulic circuit. As a result, there is a problem that durability of the hydraulic motor and the hydraulic equipment is lowered. Similarly, when the operator operates a switch (not shown) for selecting the rotation direction of the rotary work machine during rotation of the hydraulic motor and reverses the rotation direction of the rotary work machine, Since the main pressure on-off valve of the control valve or the on-off valve of the operation pilot pressure of the control valve is suddenly switched in the opposite oil inflow direction, an abrupt change in oil pressure occurs in the hydraulic circuit, causing cavitation and peak pressure There is also a problem that occurs.

  The present invention has been made paying attention to the above-mentioned problems, and even if a lock lever or the like that shuts off the original pressure or pilot pressure of the control valve is operated unexpectedly, or an operation that reverses the rotation direction of the work implement is performed. However, an object of the present invention is to provide a hydraulic control circuit for a rotary working machine that can prevent cavitation and peak pressure from occurring in the hydraulic circuit of the control valve.

To achieve the above object, the first invention provides a hydraulic control circuit for a rotary working machine,
A control valve that controls at least one hydraulic motor that drives the rotary work machine by switching the rotation direction by switching the pressure oil from the hydraulic source;
A pilot operated valve for controlling the opening of the control valve;
A lock valve that switches supply or shut-off of pressure oil from a hydraulic source to the control valve or pilot pressure of the pilot operation valve;
A work implement lock detection sensor for detecting an operation position of a lock lever for selecting a switching operation of the lock valve;
When a lock signal is input from the work implement lock detection sensor, a command to close the control valve by gradually decreasing the opening degree of the control valve at a predetermined change rate or less is output to the pilot operation valve. And a controller that outputs a command to close the valve.

  In this case, a work machine forward / reverse selection switch for selecting a rotation direction of the rotary work machine is provided, and the controller is configured to switch from the work machine forward / reverse selection switch during rotation of the rotary work machine. Even if a selection signal for reverse rotation in the current rotation direction is input, it is preferable to perform control to maintain the current rotation direction.

In the hydraulic control circuit of the rotary work machine,
A control valve that controls at least one hydraulic motor that drives the rotary work machine by switching the rotation direction by switching the pressure oil from the hydraulic source;
A work implement forward / reverse selection switch for selecting the rotation direction of the rotary work implement;
When the rotary working machine is driven to rotate by the control valve, even if a reverse direction selection signal is inputted from the work machine forward / reverse selection switch, the current rotation direction is set by the control valve. And a controller that outputs a control command to be maintained.

  According to the first invention, when the lock lever is operated to the lock side, the controller first outputs a command to gradually reduce the opening degree of the control valve to gently decelerate and stop the hydraulic motor for driving the rotary work machine. Thereafter, since a command to close the lock valve is output, cavitation and peak pressure do not occur in the hydraulic circuit of the hydraulic motor. For this reason, the load to hydraulic equipment, such as a control valve and a hydraulic motor, is reduced, and durability can be improved.

  According to the second and third inventions, when the work implement forward / reverse selection switch is selected from the current rotation direction to the reverse rotation direction while driving the rotary work machine, this selection signal is not accepted. Since the control is performed so as to maintain the current rotation direction, it is possible to prevent the occurrence of cavitation and peak pressure in the hydraulic circuit due to the rapid reversal control of the control valve. Thereby, the load to the hydraulic equipment in the hydraulic circuit can be reduced, and durability can be improved.

  Hereinafter, an embodiment of a hydraulic control circuit of a rotary working machine according to the present invention will be described with reference to the drawings. Note that, as an application machine of the present invention, a work vehicle including a rotary excavator will be described as an example.

  First, a work vehicle equipped with a rotary excavator will be described with reference to FIG. The work vehicle 1 includes a pair of left and right crawler type traveling devices 2 and 2 on the lower left and right sides of the vehicle body 1a, and a driver's cab 4 on the upper rear side of the vehicle body 1a. A driver's seat 4a is provided in the driver's cab 4, and the work implement is locked to either the left or right side of the driver's seat 4a (usually, the side that passes when the operator leaves the driver's seat 4a, which is the left side in this example). A lever 5 is provided. One end of a pair of left and right work implement support frames 6, 6 extending forward is vertically rocked on the outer side of the track frames 3, 3 provided in the front-rear direction on the pair of left and right crawler type traveling devices 2, 2. The rotary excavator 20 is provided at the other end of the pair of left and right work machine support frames 6, 6. The rotary excavator 20 has a cylindrical shape at the front of a base member 27 that is swingably mounted in the front-rear direction on the other end of the pair of left and right work machine support frames 6, 6. A rotor 21 having an excavating blade portion is rotatably provided on the outer periphery of the rotor. Above the rotor 21, a hydraulic motor 19 that rotationally drives the rotor 21 is provided, and the hydraulic motor 19 and the rotor 21 are connected by a power transmission mechanism 22 including, for example, a gear. Also, hydraulic cylinders 28 and 28 for driving the rotary excavator 20 to move up and down are attached between the left and right front end portions of the vehicle body 1a and the base member 27, and the pair of left and right work machine support frames 6 and 6 are attached. A hydraulic cylinder (not shown) that drives the rotary excavator 20 to swing in the front-rear direction (hereinafter referred to as tilt) is attached between any one of these and the base member 27.

  FIG. 2 shows a main part of the hydraulic control circuit according to the embodiment. In FIG. 2, the output port of the hydraulic pump 15 that is driven to rotate by the engine 7 is connected to the input port of the main control valve 17 for driving the rotor via a conduit 24a and via the conduit 24c. The pressure reducing valve 14 is connected to the input port. The return port of the main control valve 17 is connected to the tank 16 via a conduit 24b, and a relief valve 18 is connected between the conduit 24a and the conduit 24b. The hydraulic motor 19 for driving the rotor is connected to the output port of the main control valve 17. The main control valve 17 is a pilot operated 4-port 3-position directional control valve in this example. The rotational power of the hydraulic motor 19 is transmitted to the rotor 21 via a power transmission mechanism 22 such as a gear mechanism or a chain drive mechanism, for example, and the rotor 21 is rotationally driven.

  In this embodiment, the hydraulic pump 15 is composed of, for example, a swash plate type variable displacement pump, and this swash plate is controlled via a swash plate control unit (not shown) based on a command from the controller 30.

  The output port of the pressure reducing valve 14 is connected to the input port of the lock valve 13 via a conduit 25a, and the drain port of the pressure reducing valve 14 is connected to the tank 16 via a conduit 25b. The pressure reducing valve 14 has a structure in which the input port and the output port are communicated at the position a, and the output port and the drain port are communicated at the position b.

  The output port of the lock valve 13 is connected to the input port of each of the rotor normal rotation valve 11 and the rotor reverse rotation valve 12, and the output port of the rotor normal rotation valve 11 and the rotor reverse rotation valve 12 is respectively the main control valve 17. Are connected to the forward rotation pilot operation section and the reverse rotation pilot operation section. The drain ports of the rotor normal rotation valve 11 and the rotor reverse rotation valve 12 are connected to the tank 16 via the pipe lines 25b and 24b, and are configured to drain the returned pilot oil into the tank 16. The rotor normal rotation valve 11 and the rotor reverse rotation valve 12 are constituted by solenoid operated switching valves, and a rotor normal rotation signal and a rotor reverse rotation signal are input from the controller 30 to each solenoid operation portion. The lock valve 13 is composed of a solenoid-operated on-off valve, and an original pressure lock signal is input from the controller 30 to the solenoid operation portion.

  In the circuit diagram of this example, only the rotor 21 is shown as the main working machine according to the present invention. However, the present invention is not limited to this, and other rotary working machines (not shown) are provided. The description of the lock valve etc. concerning these working machines is omitted.

  FIG. 3 is a block diagram of the configuration of the control device according to the embodiment. In FIG. 3, as input of operator operation information, a rotor start switch 31 for instructing start of the rotor 21, a rotor stop switch 32 for instructing stop of the rotor 21, and the rotation direction (forward or reverse) of the rotor 21 And a work implement lock detection sensor 34 for detecting the lock state of the work implement lock lever 5. Each detection signal is input to the controller 30. Here, a rotor operation lever (not shown) selects and commands start and stop. In this case, the rotor start switch 31 is constituted by a limit switch for detecting the start position of the rotor operation lever. The rotor stop switch 32 includes a limit switch for detecting the stop position of the rotor operation lever. The work implement lock detection sensor 34 includes a limit switch that detects that the work implement lock lever 5 has been operated to the lock position.

  The controller 30 is mainly composed of an arithmetic device such as a microcomputer, and inputs detection signals from the switches 31, 32, 33 and the detection sensor 34, and arithmetic processing as will be described later based on these input signals. Thus, the output of the command signal of the rotor normal rotation valve 11, the rotor reverse rotation valve 12 and the lock valve 13 is controlled to appropriately control the rotation and stop of the hydraulic motor 19. Further, a monitor panel display 40 is provided in the cab 4, and the controller 30 outputs an alarm display command and the like related to the control processing to the monitor panel display 40. The monitor panel display 40 is provided with, for example, a reverse operation prohibition lamp, a forward or reverse display (lamp or LED), or an alarm message display (liquid crystal display or the like). These reverse operation prohibition lamps and forward or reverse indications are displayed, for example, when the rotation direction opposite to the current rotation direction is selected by the rotor forward / reverse selection switch 33 during the rotation of the hydraulic motor 19. , Lighting or flashing. As one means for controlling the driving of the working machine, a working machine control valve 23 for controlling the lift (elevating / lowering) and tilting drive hydraulic cylinder 28 of the rotor 21 is provided.

Next, a control processing procedure according to the present embodiment will be described based on the control flowchart shown in FIG.
First, in step S1, the controller 30 checks whether or not the work implement lock lever 5 is off (lock release side) based on the detection signal input from the work implement lock detection sensor 34. The process of step S1 is repeated to wait for the work implement lock lever 5 to be turned off. When it is off, next, in step S2, an open command is output to the lock valve 13, and the discharge pressure oil from the hydraulic pump 15 is supplied to the rotor normal rotation valve 11 and the rotor reverse rotation valve 12 via the pressure reducing valve 14. . Next, in step S3, the forward / reverse selection signal of the rotor forward / reverse selection switch 33 is fetched, and in step S4, the rotor forward / reverse mode is set in accordance with the inputted forward / reverse selection signal.

  Next, in step S5, it is checked whether the rotor start switch 31 has been turned on from the off state. If not, the process returns to step S3 and the above processing is repeated. If the rotor start switch 31 has been turned on, the above-described rotor is set in step S6. The rotor starting process in the rotational direction corresponding to the forward rotation mode or the reverse rotation mode is performed. Here, in this rotor starting process, the rotor normal rotation mode or the reverse rotation mode respectively corresponding to the set rotor normal rotation mode or reverse rotation mode is set so that the circuit pressure of the hydraulic motor 19 for driving the rotor 21 rises gently as shown in FIG. A normal rotation signal or a reverse rotation signal that gradually increases over a predetermined time is output to the solenoid operation portion of the valve 11 or the rotor reverse rotation valve 12. Thereby, the opening degree of the main control valve 17 gradually increases from the closed position to the open position during the predetermined time, and the hydraulic motor 19 is smoothly accelerated to a predetermined rotation speed.

  Next, in step S7, it is checked whether or not the rotor forward / reverse selection switch 33 has been switched while the rotor is rotating. If switched, the switching operation is not accepted in step S8, and the rotation direction is switched while the rotor is rotating. An alarm display command notifying that an abnormal operation has been performed is output to the monitor panel display 40 to warn the operator. This prohibits an abnormal operation for switching the rotation direction during rotor rotation. After this, or when the rotor forward / reverse selection switch 33 has not been switched during the rotor rotation in step S7, it is next checked in step S9 whether the rotor stop switch 32 has been turned on. When turned on, a rotor stop process is performed in step S11. Here, in this rotor stop process, the rotor corresponding to the selected rotor forward rotation mode or reverse rotation mode so that the circuit pressure of the hydraulic motor 19 for driving the rotor 21 gradually decreases as shown in FIG. A normal rotation signal or a reverse rotation signal that gradually decreases to a rotation stop over a predetermined time is output to the solenoid operation portion of the normal rotation valve 11 or the rotor reverse rotation valve 12. Thereby, the opening degree of the main control valve 17 gradually decreases from the open position to the closed position during a predetermined time, and the hydraulic motor 19 is smoothly decelerated and finally stopped. In addition, after starting the said rotor stop process, restart is prohibited within predetermined time until the hydraulic motor 19 stops substantially.

  If the rotor stop switch 32 is not turned on in step S9, it is checked in step S13 whether the work implement lock lever 5 is turned on. If it is turned on, rotor stop processing is executed in step S14. The rotor stop process is the same as the process in step S11. Then, after a predetermined time (time until substantially stopping) has elapsed since the start of the rotor stop process, a close command is output to the lock valve 13 in step S15 and the drive pressure to the rotor normal rotation valve 11 and the rotor reverse rotation valve 12 is output. Oil (original pressure) is shut off, and the process returns to step S1 to repeat the above processing. If the work implement lock lever 5 is not turned on in step S13, the process returns to step S7 to repeat the process.

  As described above, when the work machine lock lever 5 is operated to the lock side while driving the hydraulic motor 19 that rotationally drives the rotor 21 (rotary excavator), first, the hydraulic motor drive A control command that gradually decreases within a predetermined time is output to the open / close valves (rotor forward rotation valve 11 and rotor reverse rotation valve 12), and the drive hydraulic pressure of the hydraulic motor 19 is gradually reduced to zero, so that the hydraulic motor 19 is smoothly moved. Stop. Thereafter, the lock valve 13 is closed to shut off the pilot oil to the on-off valve, and the operation of the hydraulic motor 19 is prohibited. Therefore, even if the work implement lock lever 5 is operated to the lock side during the operation of the hydraulic motor, it is possible to prevent cavitation and peak pressure from occurring in the hydraulic circuit. As a result, the load on the hydraulic equipment is reduced, so that the durability of the hydraulic equipment can be improved and the cost of the hydraulic equipment used can be reduced.

  In addition, even if the work implement forward / reverse selection switch 33 is operated and the direction opposite to the current rotation direction is selected while the hydraulic motor 19 is being driven, the current rotation direction is changed without accepting this selection. Since the control to maintain is performed, there is no sudden change in the hydraulic pressure, and cavitation and peak pressure can be prevented from occurring in the hydraulic circuit. Therefore, the durability of the hydraulic device can be improved and the cost of the hydraulic device can be reduced. Furthermore, when the selection of the work implement forward / reverse selection switch 33 is not accepted in this way, the alarm display that informs the operator to that effect is displayed on the monitor panel display 40, so that the operator can immediately understand his or her operation mistake. Since care is taken not to make an operation mistake, the operability can be improved and the durability of the hydraulic equipment can be improved.

  Conventionally, in order to prevent the occurrence of cavitation and peak pressure, a suction valve using a check valve is installed between the tank 16 and the hydraulic motor 19 so as to suck oil into the hydraulic motor 19 side. However, it is possible to simplify the hydraulic circuit by reducing the number of hydraulic components by eliminating the need for extra hydraulic equipment such as a suction valve. Furthermore, when the work machine lock lever 5 is operated to the lock side while the hydraulic motor 19 is being driven, the opening of the control valve 17 is gradually reduced as described above to gently reduce the drive hydraulic pressure of the hydraulic motor 19. Thereafter, the lock valve 13 is closed, but when the hydraulic motor 19 is driven next time, the work implement lock lever 5 is turned off (unlocked), and the operation lever (rotor operation lever) is temporarily moved to the stop position. Since the start is started only when it is operated to the start position after returning, it can be prevented from being restarted only by unlocking the work machine lock lever 5, and the hydraulic motor can be more reliably operated based on the operation of the operator. Can start.

  In the embodiment, the pilot valve pressure of the rotor normal rotation valve 11 and the rotor reverse rotation valve 12 that pilot-operate the control valve 17 has been described as being configured to supply or shut off with the lock valve 13, but the present invention is not limited thereto. Alternatively, a circuit configured to switch the supply or shutoff of the hydraulic pressure (original pressure) from the hydraulic pump 15 to the control valve 17 by the lock valve 13 may be used.

  In the embodiment, the work vehicle including the rotor 21 is described as an example of the rotary excavator. However, the application machine of the present invention is not limited to this, and the work machine including other rotary work machines may be used. Is also applicable.

It is a side view of a work vehicle provided with a rotary excavator according to the present invention. It is a principal part of the hydraulic control circuit which concerns on embodiment of this invention. It is a control unit block diagram concerning an embodiment of the present invention. It is a control flowchart concerning the embodiment of the present invention. It is a characteristic explanatory view of work implement drive oil pressure concerning control of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Work vehicle, 2 ... Traveling apparatus, 3 ... Track frame, 4 ... Driver's cab, 5 ... Work implement lock lever, 6 ... Work implement support frame, 7 ... Engine, 11 ... Rotor normal rotation valve, 12 ... Rotor reverse rotation valve , 13 ... Lock valve, 14 ... Pressure reducing valve, 15 ... Hydraulic pump, 16 ... Tank, 17 ... Main control valve, 18 ... Relief valve, 19 ... Hydraulic motor, 20 ... Rotary excavator, 21 ... Rotor, 22 ... Power Transmission mechanism, 23 ... work machine control valve, 24a, 24b, 24c ... pipe, 25a, 25b ... pipe, 27 ... base member, 28 ... hydraulic cylinder, 30 ... controller, 31 ... rotor start switch, 32 ... rotor stop Switch, 33 ... Rotor forward / reverse selection switch (work implement forward / reverse selection switch), 34 ... Work implement lock detection sensor, 40 ... Monitor panel display.

Claims (3)

In the hydraulic control circuit of a rotary work machine,
A control valve (17) for controlling at least one hydraulic motor (19) for driving the rotary work machine (21) by switching the rotation direction by switching the pressure oil from the hydraulic source;
Pilot operated valves (11, 12) for controlling the opening of the control valve (17);
A lock valve (13) for switching supply or shut-off of pressure oil from a hydraulic pressure source to the control valve (17) or pilot pressure of the pilot operation valve (11, 12);
A work implement lock detection sensor (34) for detecting an operation position of a lock lever (5) for selecting switching operation of the lock valve (13);
When the lock signal from the work implement lock detection sensor (34) is input, a command to close the pilot valve (11, 12) by gradually decreasing the opening degree of the control valve (17) below a predetermined change rate. And a controller (30) for outputting a command for closing the lock valve (13) after a predetermined time has elapsed. In the hydraulic control circuit of the rotary working machine according to claim 1,
A work machine forward / reverse selection switch (33) for selecting a rotation direction of the rotary work machine (21);
Even if the controller (30) inputs a reverse selection signal in the current rotation direction from the work implement forward / reverse selection switch (33) during the rotation of the rotary work machine (21), the current rotation direction A hydraulic control circuit for a rotary working machine, characterized in that control for maintaining the pressure is performed. In the hydraulic control circuit of a rotary work machine,
A control valve (17) for controlling at least one hydraulic motor (19) for driving the rotary work machine (21) by switching the rotation direction by switching the pressure oil from the hydraulic source;
A work implement forward / reverse selection switch (33) for selecting the rotation direction of the rotary work implement (21);
When the rotary work implement (21) is rotationally driven by the control valve (17), a reverse selection signal in the current rotational direction may be input from the work implement forward / reverse selection switch (33). And a controller (30) for outputting a control command for maintaining the current rotation direction by the control valve (17).