JP5067290B2 - Work machine - Google Patents

Description

  The present invention relates to a work machine of a two-pump system having a plurality of hydraulic actuators and having two hydraulic pumps as the hydraulic source.

  As shown in FIG. 5, the hydraulic excavator includes a base machine B in which an upper swing body 2 is mounted on a crawler-type lower traveling body 1 so as to be rotatable about a vertical axis, and an upper swing body of the base machine B. 2, the boom 3, the arm 4, the bucket 5 and the shovel attachment A <b> 1 including the boom, arm, and bucket cylinders (hydraulic cylinders) 6 to 8 for operating the boom 3, the arm 4, and the bucket 5 are mounted.

  Further, as other hydraulic actuators, left and right traveling motors that drive the lower traveling body 1 and a swing motor (none of which is shown) that swings the upper swing body 2 are provided.

  In this hydraulic excavator, it is general that all hydraulic actuators are divided into two groups, and the actuator groups of both groups are driven by separate hydraulic pumps (first and second hydraulic pumps).

  The above configuration is shown in Patent Document 1.

  On the other hand, this excavator may be diverted to other working machines, for example, a wood processing machine for cutting, pruning, and transporting trees.

  In this case, as shown in FIG. 6, the bucket 5 is removed from the tip of the shovel attachment A1, and instead, a wood processing unit (hereinafter referred to as a processor according to a common name) 9 is mounted to constitute the wood processing attachment A2.

  The processor 9 includes a big saw that cuts a large tree, a small saw that cuts a small tree, a grab that grabs and transports wood, a wheel that slides and prunes the wood, a harvester as a frame that bundles these, and a plurality of operating these Hydraulic actuators (hereinafter collectively referred to as processor actuators).

  When the processor 9 is attached to the tip of the attachment and converted from a hydraulic excavator to a wood processing machine, the processor actuator is connected to, for example, the second group, and the excavator actuators of the same group (both traveling and turning motors and boom and arm both) are connected. Together with the cylinder) and is driven by the oil discharged from the second pump.

The wood processing machine is shown in Patent Documents 2 and 3.
JP 2001-295804 A JP 2002-154104 A JP 52-57597 A

  However, according to the above configuration, the load frequency of the second hydraulic pump increases as the processor actuator is added. Moreover, in wood processing machines, processor actuators are frequently used, which increases the risk of damage to the couplings and bearings of the pump, resulting in a problem that the life is significantly shorter than that of the first hydraulic pump. It was.

  Although it is conceivable to add a hydraulic pump dedicated to the processor actuator, it is not practical because the equipment cost including the pump becomes high and it is difficult to secure a space for the additional equipment.

  Therefore, the present invention provides a working machine capable of increasing the pump life by equalizing the loads of both hydraulic pumps on the premise of a two-pump system.

  According to the first aspect of the present invention, in the work machine configured to divide the hydraulic actuator group into two groups and to drive each group by the first and second hydraulic pumps, the maximum required flow rate is covered by only one hydraulic pump. For the hydraulic actuator that is equivalent to a single flow to be obtained, it is configured to perform small merging control to supply the discharge oil of both hydraulic pumps by joining them in a truncated state where the total discharge flow rate is equivalent to the single flow. Is.

  The invention of claim 2 is the configuration of claim 1, wherein the maximum required flow rate is equivalent to a single flow that can be covered by only one hydraulic pump, and the maximum required flow rate is the sum of the maximum discharge amounts of both hydraulic pumps. A large flow rate actuator that is equivalent to merging that can only be covered is provided, and small merging control is performed when the small flow rate actuator is activated, and the total discharge amount of both hydraulic pumps is equivalent to merging when the large flow rate hydraulic actuator is activated. It is configured to perform large merging control by merging and supplying in a state.

  According to a third aspect of the present invention, in the configuration of the first or second aspect, a work attachment is attached to the base machine, and the work attachment includes an arm at the tip of the boom and a work machine attached to the tip of the arm. The small merging control is performed when the small flow rate actuator for the working machine is operated.

  According to a fourth aspect of the present invention, in the configuration of the third aspect, a wood processing unit for performing wood processing such as cutting, pruning or transporting a tree is attached as a working machine.

  According to a fifth aspect of the present invention, in the configuration of the third or fourth aspect, the combined discharge flow rates of both hydraulic pumps are simply reduced during the combined operation in which the operation of the small flow hydraulic actuator and the operation of the base machine, boom or arm are performed simultaneously. The discharge amount of at least one of the hydraulic pumps is increased so that the value is equal to or greater than the flow and equal to or less than the merge.

  According to a sixth aspect of the present invention, in the configuration of the fifth aspect, in accordance with the operation amount of the operation means that commands the operation of each hydraulic actuator, positive control is performed to control the pump discharge amount as the required flow rate increases as the operation amount increases. As a premise, during the combined operation including the boom raising operation, when the boom raising operation amount exceeds the set value, the small merging control for the small merging actuator is canceled and only the discharge oil of one hydraulic pump is discharged. It is configured to switch to the single flow control to be supplied.

  According to the present invention, for the hydraulic actuator corresponding to a single flow that can be covered by the discharge oil of one pump, the discharge oil of the two hydraulic pumps is combined and supplied in a truncated state where the total flow rate is equivalent to a single flow. Therefore, both hydraulic pumps can be controlled by using a hydraulic actuator that is frequently used (a hydraulic actuator for a working machine in claim 3 and a hydraulic actuator for a processor in claim 4) as a control target. It is possible to reduce the risk of breakage by equalizing the load of the two pumps and consequently improve the service life of both pumps.

  In this case, according to the second aspect of the present invention, in a machine having both a small flow rate actuator that requires a small merge and a large flow rate actuator that requires a large merge, a small merge operation and no head cut depending on the actuator. Therefore, the two functions of protecting the pump and ensuring the work function with a large flow rate can be achieved at the same time.

  According to the fifth and sixth aspects of the present invention, the supply flow rate is increased more than the small merge control during the combined operation in which the operation of the small flow hydraulic actuator and the operation of the base machine, the boom or the arm are performed simultaneously. Can be avoided.

  By the way, in the combined operation including the boom raising operation, the boom raising operation pressure is high, and therefore the boom raising flow rate tends to be insufficient. In particular, in a machine that performs positive control, even if the pump discharge amount is increased in response to an increase in boom raising operation amount (boom rapid raising command), the boom raising speed does not increase as expected.

  In this respect, according to the invention of claim 6, when the boom raising operation amount becomes equal to or greater than the set value, the small merging control is canceled and switched to the single flow control. Can be ensured.

  An embodiment of the present invention will be described with reference to FIGS.

  In the embodiment, a case where a wood processing machine is configured by attaching a processor to the tip of an attachment of a hydraulic excavator will be described as an example.

  FIG. 1 shows the configuration of an excavator's original hydraulic circuit (excavator circuit).

  This shovel circuit includes, as hydraulic actuators, boom, arm, and bucket cylinders 6, 7, and 8, and left and right traveling motors 10 and 11 and a swing motor 12.

  The hydraulic actuator group and the hydraulic pilot type control valve group for individually controlling these hydraulic actuator groups are divided into first and second groups G1 and G2.

  The first group G1 on the right side of the drawing is composed of a right traveling motor 11, a boom cylinder 6, a bucket cylinder 8, and control valves 13, 14, 15 which are hydraulic pilot switching valves for individually controlling them.

  Note that an arm second speed control valve for increasing the speed of the arm cylinder 7 may be provided in the first group.

  The second group G2 on the left side of the figure is composed of a left traveling motor 10, a turning motor 12, an arm cylinder 7, and control valves 16, 17, 18 which are hydraulic pilot switching valves for individually controlling them.

  The control valves 13 to 15 and 16 to 18 of the two groups G1 and G2 are connected in tandem by the center bypass lines C1 and C2, with the travel motor control valves 13 and 16 being on the most upstream side, respectively. The other control valves 14, 15, 17, and 18 are connected in parallel to a pressure oil supply line L provided separately from the center bypass lines C1 and C2. T is a tank.

  Further, a remote control valve is provided for each control valve, and a pressure sensor for detecting the pilot pressure of the remote control valve as a control valve operation amount is provided. However, here, only the pressure sensor 19 for detecting the boom raising pilot pressure related to the invention of claim 6 is shown, and the others are omitted.

  On the other hand, a first hydraulic pump 20 responsible for the first group G1 and a second hydraulic pump 21 responsible for the second group G2 are provided as pressure oil supply sources for the hydraulic actuator group.

  Both hydraulic pumps 20, 21 are provided with pump regulators 22, 23, and the discharge amounts (tilts) of both hydraulic pumps 20, 21 are controlled by the shovel controller 24 through these regulators 22, 23.

  Here, the pump discharge amount is controlled by a positive control that assumes that the required flow rate increases as the operation amount of the remote control valve for each actuator increases.

  In the excavator circuit, it is necessary to supply the same amount of oil to the left and right traveling motors 10 and 11 and drive them at the same speed during a complex operation including a traveling operation such as turning while traveling (during a traveling complex operation). Therefore, as described above, the left and right traveling motors 10 and 11 are divided into different groups G2 and G1, and are driven by separate pumps except during the traveling combined operation, while the discharge oil of the same pump is used for both traveling motors 10 during the traveling combined operation. , 11 is distributed and supplied.

  Therefore, it is necessary to switch the oil flow paths from both the hydraulic pumps 20 and 21 during the traveling combined operation and other times.

  Therefore, a traveling straight valve (hereinafter referred to as a straight traveling valve according to a general abbreviation) 25 for performing this switching is provided in the pump lines of both hydraulic pumps 20 and 21, and the discharge oil of both pumps 20 and 21 travels straight. The two groups G1 and G2 are supplied via the valve 25 or directly.

  The straight valve 25 has a single operation position (single flow position in terms of merging / single flow described later) and a combined operation position (same merging position) B, and two pump ports P1. , P2 and a two-position four-port hydraulic pilot switching valve having two actuator ports a and b, which are connected to the pump lines of both hydraulic pumps 20 and 21.

  The straight running valve 25 is switch-controlled by the secondary pressure of the straight running control valve 26 as an electromagnetic proportional switching control valve based on a command from the shovel controller 24. A straight running pilot line 27 connects the secondary side of the straight running control valve 26 and the pilot port of the straight running valve 25.

  The shovel controller 24 receives an operation signal (a pilot pressure signal including a boom raising pilot pressure signal Ps1 from the pressure sensor 19) according to the operation amount of each remote control valve, and performs a traveling operation and other operations (work operations). ) Are performed separately, the straight running valve 25 is in the illustrated single operation position a.

  In this state, the discharge oil of the first pump 20 passes through the passage P1-b of the straight valve 5 to the first group G1, and the discharge oil of the second pump 21 is supplied directly to the second group G2.

  On the other hand, during the traveling combined operation in which the traveling operation and the work operation are performed at the same time, the straight valve 25 is switched from the single operation position A to the combined operation position B based on a signal from the shovel controller 24.

  In this state, the oil discharged from the first pump 20 passes through the passage P1-a of the straight valve 25 and the pressure oil supply line L and is parallel to the hydraulic actuators 6, 7, 8, 12 other than the travel motors 10, 11. On the other hand, the oil discharged from the second pump 21 is distributed and supplied to both travel motors 10 and 11.

  Thus, since both travel motors 10 and 11 are driven by the common second pump 21, if the same amount of left and right travel is operated, the same amount of oil is supplied to both travel motors 10 and 11 so that they have the same speed. Rotate. That is, traveling straightness is ensured.

  The straight travel valve 25 is also switched to the composite operation position B during a composite operation in which a plurality of hydraulic actuators other than the travel motors 10 and 11 belonging to the same group are operated simultaneously.

  In this state, the discharge oils of the hydraulic pumps 20 and 21 merge at the merge point O, and the flow rate required for the plurality of hydraulic actuators to operate simultaneously is secured by this merge action.

  By the way, in the state where the straight running valve 25 is set to the combined operation position b, the discharge oil of the second hydraulic pump 21 is distributed to the center bypass lines C1, C2 of both groups G1, G2, as described above. When one of the actuators of the groups G1 and G2 is operated, if the other center bypass line C1 or C2 is left connected to the tank T, all the pump discharge oil is unloaded, and a situation occurs in which the actuator does not operate.

  Therefore, hydraulic pilot type cut valves 28 and 29 for closing the lines C1 and C2 as necessary are provided on the most downstream side of the center bypass lines C1 and C2.

  The cut valves 28 and 29 are unload positions where the center bypass line C1 communicates with the tank T as shown in the figure by a pilot pressure sent from an electromagnetic proportional valve (not shown) based on a signal from the shovel controller 24. And the block position B which is shut off with respect to the tank T.

  Of these cut valves 28 and 29, the cut valve 28 on the first group G1 side is operated when one of the control valves on the second group G2 side is operated, and the cut valve 29 on the second group G2 side is the first group G1. When one of the control valves on the side is operated, it switches to the block position b.

  This action ensures the actuator operation of both groups G1, G2.

  When the wood processing machine is configured based on the hydraulic excavator provided with the above excavator circuit, the hydraulic actuator group provided in the processor 9 is connected to the second group G2 via the option valve 30.

  The option valve 30 is configured as a hydraulic pilot switching type directional control valve, and is controlled by a processor controller 32 in FIG. 1 and 2, a third hydraulic pump 33 as a pilot hydraulic source of the option valve 30, and a pressure 34 detects the pilot pressure (switching state) of the option valve 30 and sends it to the excavator controller 24 as a pilot pressure signal Ps 2. It is a sensor.

  The processor 9 is a big saw that cuts a large tree as described above, a small saw that cuts a small tree, a wheel that slides and prunes wood by rotating and opening and closing the wheel, and a grab that grabs and transports the wood. It comprises a harvester (not shown) as a frame, hydraulic actuators (hydraulic cylinders or hydraulic motors) 35-40 for driving them, and switches 41-46 for commanding the operation of these actuators.

  Further, there is provided a merging changeover switch 47 which is switched and operated based on a signal from the processor controller 32 in accordance with the type of actuator to be operated, and a switching signal of the merging changeover switch 47 is sent to the shovel controller 24 to be joined. The control is selected and executed from “small merge control” and “large merge control”.

  “Small merge control” means a small flow rate actuator (small saw motor 35, wheel opening / closing cylinder 38, grab opening / closing cylinder 39, harvester raising cylinder 40) whose maximum required flow rate is equivalent to a single flow that can be covered only by the second hydraulic pump 21. On the other hand, the oil discharged from both hydraulic pumps 20 and 21 is in a truncated state where the sum of the respective discharge flow rates is equivalent to a single flow (for example, the first hydraulic pump 20 is 45% of the maximum discharge amount and the second hydraulic pump 21 is 55% of the ratio).

  On the other hand, “large merging control” refers to both large flow rate actuators (big saw motor 36 and wheel rotation motor 37) whose maximum required flow rate is equivalent to merging that can be covered only by the sum of the maximum discharge amounts of both hydraulic pumps. This is a control in which the sum of the discharge amounts of the hydraulic pumps 20 and 21 is equivalent to the confluence (no head cut = maximum discharge amount) and is supplied after full confluence.

  The overall operation including this point will be described with reference to the flowcharts of FIGS.

  The flowchart of FIG. 3 shows the basic operation.

  After the control is started, it is determined in step S1 whether or not the processor switch (at least one of the switches 41 to 46) has been turned on. If YES, the switching of the merge switch 47 in FIG. 2 is switched in step S2. It is determined which of the large merging control and the small merging control is to be executed based on the change signal (determined by the type of the operated switch).

  That is, when the small saw, wheel opening / closing, grab opening / closing, and harvester raising switches 41, 44 to 46 are operated, the small merge control is determined, and when the big saw and wheel rotation switches 42, 43 are operated, the large merge control is determined.

  If it is determined that the large merging control is selected, the straight valve 25 in FIG. 1 is switched to the merging position (combined operation position) B in step S3, and both hydraulic pumps 20, 21 are controlled to the maximum tilt in step S4. Is done.

  As a result, the maximum discharge amounts of the first and second hydraulic pumps 20 and 21 merge and are supplied to the processor actuator (the big saw motor 36 or the wheel rotation motor 37).

  On the other hand, when it is determined that the small merging control is performed, the straight valve 25 is switched to the merging position (combined operation position) B in step S5. However, in the subsequent step S6, the merging flow rates of the hydraulic pumps 20 and 21 are simply set. The tilting of both hydraulic pumps 20 and 21 is controlled so that they merge in a head-cutting state corresponding to the flow (for example, 45%: 55% of the maximum discharge amount).

  This control is continued until it is determined in step S7 that the processor switch is turned off. After the processor switch is turned off, both the hydraulic pumps 20 and 21 are controlled to the minimum tilt (step S8), and the straight running valve 25 is switched. Release (return to single flow position a) completes control.

  In this way, when the hydraulic actuator whose required flow rate is equivalent to a single flow (a flow rate that can be covered by only one pump discharge oil) is actuated, the discharge oils of both hydraulic pumps 20 and 21 are combined and supplied in a head-off state. Therefore, the problem that the load frequency of the pump 21 is increased and the risk of breakage is increased as in the case where the configuration is covered only by the second hydraulic pump 21 as in the prior art is solved. , 21 can be improved (equalized).

  Based on actual work measurement data of wood processing, regarding the life improvement of both hydraulic pumps 20, 21, the effect of shaft spline surface pressure life La and bearing life Lb when the life in excavation work is assumed to be 100% went.

  As a result, while La was 9.6% and Lb was 23.9%, La was improved by 137% and Lb was 121%.

  FIG. 4 shows an operation when a composite operation in which the boom 3 or the arm 4 is operated is performed during the execution of the small merging control for the hydraulic actuator for processor (when the small flow rate actuator is operated).

  Steps S11 to S16 related to the small merge or large merge control for the processor hydraulic actuator are the same as steps S1 to S6 in FIG.

  In step S17, it is determined whether or not there is an excavator operation (boom operation, arm operation, turning operation, traveling operation). If NO (no excavator operation), step S18 corresponding to step S7 to step S9 in FIG. Control proceeds to step S20.

  On the other hand, if YES in step S17 (with excavator operation), in step S21, the tilting of both hydraulic pumps 20, 21 is controlled so that the total flow rate of both hydraulic pumps 20, 21 becomes a single flow equivalent plus α.

  “Single flow equivalent plus α” means a value where the sum of the discharge flow rates of the hydraulic pumps 20 and 21 is greater than or equal to the single flow and less than or equal to the full merge (for example, an increase of 10% corresponding to the single flow).

  In this way, since the supply flow rate is increased during the combined operation with the shovel operation compared to the small merge control, it is possible to avoid the shortage of the flow rates of both the processor actuator and the shovel actuator.

  By the way, in the combined operation including the boom raising operation, since the boom raising operating pressure is high, the flow rate is taken by another actuator having a low operating pressure, and the boom raising flow rate tends to be insufficient.

  Therefore, it is determined whether or not the shovel operation includes a boom raising operation in step S22, and whether or not the boom raising pilot pressure (operation amount) is equal to or higher than a set value in step S23. The direct valve 25 is switched to the single flow position (single operation position) a.

  By switching the straight running valve 25, the discharge oil of the first hydraulic pump 20 is supplied to the first group G1, and the discharge oil of the second hydraulic pump 21 is supplied to the second group G2 including the processor actuator. Therefore, it is possible to secure a sufficient flow rate for raising the boom and to ensure the rapid raising operation of the boom.

  In step S25, it is determined again whether or not the boom raising pilot pressure is equal to or higher than the set value. If NO, the straight running valve 25 is switched again to the merging position (composite operation position) in step S26 and the process returns to step S22. .

  If it is determined in step S22 that the boom raising operation is not included, it is determined in step S27 whether or not there is an excavator operation. If it is determined that there is no shovel operation, the original small merge control is switched in step S28. Return to S17.

Other Embodiments (1) In the above embodiment, the processor 9 having both the small flow rate actuator and the large flow rate actuator is configured to switch between the small merge control and the large merge control. In the case where only the actuator is provided, a configuration that is limited to the small merge control may be employed.

  (2) In the above embodiment, the case where the wood processing machine is configured by attaching the wood processing processor 9 to the tip of the attachment is taken as an example, but the present invention is a two-pump in which a working machine other than the processor 9 is attached. Can be widely applied to system machines.

It is a circuit diagram of an excavator circuit showing an embodiment of the present invention. 2 is a circuit diagram of the processor circuit. FIG. It is a flowchart for demonstrating a basic effect | action. It is the flowchart which added the effect | action at the time of compound operation with shovel operation to the basic effect | action. It is a schematic side view of a hydraulic excavator. It is a schematic side view of the wood processing machine which is a diversion example of a hydraulic shovel.

Explanation of symbols

B Base machine A1 Excavator attachment as work attachment A2 Same wood processing attachment 1 Lower traveling body of base machine 2 Same upper swing body 3 Boom 4 Arm 5 Bucket 6 Boom cylinder 7 Arm cylinder 8 Bucket cylinder 9 Processor (Wood processing unit) )
DESCRIPTION OF SYMBOLS 10,11 Left and right traveling motor 12 Rotating motor 19 Pressure sensor for detecting boom raising pilot pressure 20 First hydraulic pump 21 Second hydraulic pump 24 Excavator controller 25 Straight running valve 32 Processor controller 35 Small saw motor as small flow rate actuator 36 Big saw motor as a large flow actuator 37 Wheel rotation motor as a large flow actuator 38 Wheel opening and closing cylinder as a small flow actuator 39 Grab opening and closing cylinder as a small flow actuator 40 Harvester raising cylinder as a small flow actuator 47 Merge switch

Claims (6)

  In a working machine configured so that the hydraulic actuator group is divided into two groups and driven by the first and second hydraulic pumps by group, the maximum required flow rate is equivalent to a single flow that can be provided by only one hydraulic pump. A working machine configured to perform small merging control for supplying the oil discharged from both hydraulic pumps to the actuator by merging them in a truncated state where the sum of the respective discharge flow rates corresponds to the single flow. .   Combined with a small flow rate actuator whose maximum required flow rate can be provided by only one hydraulic pump and a large flow rate actuator whose maximum required flow rate can be provided only by the sum of the maximum discharge amounts of both hydraulic pumps. The small flow control is performed when the small flow actuator is operated, and the large flow control is performed when the large flow hydraulic actuator is operated so that the sum of the discharge amounts of both hydraulic pumps corresponds to the merge. The work machine according to claim 1, wherein the work machine is configured.   A work attachment is attached to the base machine, and this work attachment has an arm attached to the tip of the boom and a work machine attached to the tip of the arm, and performs small merging control when the small flow actuator for this work machine is operated. 3. The work machine according to claim 1, wherein the work machine is configured as described above.   4. The work machine according to claim 3, wherein a wood processing unit that performs wood processing such as cutting, pruning, and transporting trees is attached as the work machine.   At least one so that the sum of the discharge flow rates of both hydraulic pumps is equal to or greater than the single flow and equal to or less than the combined flow during the combined operation in which the operation of the small flow hydraulic actuator and the base machine, boom or arm are performed simultaneously. 5. The work machine according to claim 3, wherein the discharge amount of the hydraulic pump is increased.   Assuming that positive control is performed to control the pump discharge amount as the required flow rate increases as the operation amount increases in accordance with the operation amount of the operation means that commands the operation of each hydraulic actuator, during complex operation including boom raising operation When the boom raising operation amount exceeds the set value, the small merging control for the small merging actuator is canceled, and the control unit switches to single flow control that supplies only the discharge oil of one hydraulic pump. The work machine according to claim 5, wherein:

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