JP2006329341A - Hydraulic control unit of working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control a communication path for preventing an abrupt speed reduction by applying a part of the oil on the working side to a traveling side, into a desired state (open state or closed state) depending on situations at compound operation in which traveling operation is simultaneously performed with working operation. <P>SOLUTION: A communication path 35 and a control valve 36 that opens/closes it are provided in a travel linear motion valve 32. At compound operation, working pressure and traveling pressure are taken in as both-side pilot pressure. So the communication path 35 is closed without condition at travel minute operation which shows a small travel operation amount, the communication path 35 is opened when the working pressure is higher than the traveling pressure at travel major operation which shows a large amount of traveling operation, and the communication path 35 is closed when the working pressure is lower than the traveling pressure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydraulic control device for a work machine such as a hydraulic excavator.

  The background art will be described using a hydraulic excavator as an example.

  As shown in FIG. 5, the hydraulic excavator has an upper swing body 2 mounted on a crawler type lower traveling body 1 so as to be rotatable around a vertical axis. The upper swing body 2 has a boom 3, an arm 4, and a bucket 5. In addition, a work (excavation) attachment 9 composed of cylinders 6, 7, 8 for raising and lowering the boom, operating the arm, and operating the bucket is mounted.

  In addition, left and right traveling motors 10 and 11 (see FIG. 6) for driving the lower traveling body 1 and a turning motor 12 (same as above) for rotating the upper rotating body 2 are provided.

  FIG. 6 shows a hydraulic control device of a hydraulic excavator.

  The hydraulic actuator group is divided into a first group G1 including a right traveling motor 11, a bucket cylinder 8, and a boom cylinder 6, and a second group G2 including a left traveling motor 10, a turning motor 12, and an arm cylinder 7. Yes.

  The hydraulic actuators of the two groups G1 and G2 are connected in tandem by center bypass lines C1 and C2 with the traveling motors 11 and 10 on the most upstream side, respectively, while the hydraulic actuators (working actuators) 6 other than the traveling motors 6 , 7, 8, and 12 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.

  For each hydraulic actuator, hydraulic pilot type control valves 13 to 18 for controlling the operation and remote control valves 19 to 24 as operation means for switching these are provided.

  On the other hand, first and second pumps 25 and 26 are provided as pressure oil supply sources for the hydraulic actuator group, and the oil discharged from both pumps 25 and 26 is a hydraulic pilot type traveling straight valve (hereinafter referred to as a general abbreviation). (Referred to as a straight running valve) 27 and supplied to both groups G1, G2.

  The straight travel valve 27 has a neutral position A and a straight travel position B, and is configured as a two-position four-port switching valve having two pump ports P1 and P2 and two actuator ports A and B. The switching is controlled by the secondary pressure of the electromagnetic proportional switching control valve 29 based on a command from the controller 28. Reference numeral 30 denotes a primary hydraulic source of the switching control valve 29.

  An operation signal (for example, a signal from a pressure sensor for detecting the remote control valve pilot pressure) corresponding to the operation amount of each remote control valve 19 to 24 is input to the controller 28, and a travel operation and a work operation (work actuators 6, 7) are input. , 8, and 12) are performed separately, the straight running valve 27 is in the neutral position a shown in the figure.

  In this state, the discharge oil of the first pump 25 is supplied to the first group G1 through the passage P1-B of the straight travel valve 27, and the discharge oil of the second pump 26 is directly supplied to the second group G2. (This state is referred to as a first pressure oil supply state).

  On the other hand, during the combined operation in which the traveling operation and the work operation are performed simultaneously, the straight travel valve 27 is switched from the neutral position a to the travel straight travel position b.

  In this state, the oil discharged from the first pump 25 is supplied to the hydraulic actuators 6, 7, 8, 12 other than the travel motors 10, 11 through the passage P 1 -A of the straight valve 27 and the pressure oil supply pipe L. On the other hand, the oil discharged from the second pump 26 is distributed and supplied to both travel motors 10 and 11 (this state is referred to as a second pressure oil supply state).

  In this second pressure oil supply state, both the traveling motors 10 and 11 are driven by the common second pump 26, so that the same amount of oil is supplied to both the traveling motors 5 and 6 when the traveling operation is performed by the same amount left and right. These rotate at the same speed. That is, traveling straightness is ensured.

  In this case, since the amount of pressure oil supplied to both travel motors 10 and 11 is halved compared to the first pressure oil supply state, the speed is also halved (rapidly decelerated) and a shock is generated.

Therefore, as a means for alleviating this shock, the first straight pump 27 is provided with a communication passage 31 and the pump lines of both pumps 25 and 26 are communicated through the communication passage 31 in the second pressure oil supply state. A part of the 25 discharged oil is sent to the traveling side (see Patent Document 1).
JP 2000-17893 A

  However, according to the publicly known technology, the following problems have occurred with the provision of the communication path 31.

  (i) When a work operation is performed during low speed travel (during travel by a so-called half lever that finely operates the travel remote control valves 19 and 22).

  In this case, when the operating pressure (working pressure) of the work actuators 6, 7, 8, and 12 is higher than the pressure (running pressure) of the travel motors 10 and 11, the discharge oil (work side oil) of the first pump 25 is reduced. It flows into the traveling side and is accelerated against the operator's will.

  Conversely, when the working pressure is lower than the traveling pressure, the oil discharged from the second pump 26 (running side oil) flows into the working side, and traveling further slows down or stops.

  Therefore, in this situation, it is desirable that the communication path 31 is closed.

  (ii) When a work operation is performed during high speed traveling (traveling with a so-called full lever that greatly operates the travel remote control valves 19 and 22).

  In this case, in a situation where the working pressure is higher than the traveling pressure, a part of the working-side oil is supplied to the traveling side as originally intended, so that sudden deceleration can be prevented. However, on the contrary, when the working pressure is lower than the traveling pressure, the oil on the traveling side turns to the working side and decelerates more rapidly.

  That is, the communication path 31 is unconditionally closed in the case (i), and is preferably opened and closed in accordance with the working pressure and the traveling pressure in the case (ii). However, in the known technique in which the communication path 31 is always open. It was not possible to meet such a request.

  Therefore, the present invention provides a hydraulic control device for a work machine that can control the communication path to a desired state (open or closed state) according to the situation.

  According to the first aspect of the present invention, a work attachment is mounted on an upper swing body mounted on a lower traveling body, and a hydraulic actuator group including a work actuator for operating the work attachment and left and right traveling motors is either left or right. A first group including a traveling motor and a second group including the other traveling motor, both first and second pumps as hydraulic pressure sources, and a traveling straight valve that switches a flow path of pump discharge oil This straight traveling valve is in a neutral position during independent operation for separately performing the traveling operation and the work operation, and supplies the pump oil discharged to the first and second groups separately. It is configured to switch to the straight travel position and supply the oil discharged from the separate pumps to both the travel motor and the work actuator at the time of combined operation in which operations are performed simultaneously. In addition, in the hydraulic control device for a work machine configured to connect the pump lines of both pumps through the communication path in the process in which the travel straight valve is switched from the neutral position to the travel straight position, the communication path is opened and closed. A control valve is provided, and at the time of combined operation, the control valve allows the following passage to be routed according to the position of the travel straight valve, the working pressure that is the working pressure of the work actuator, and the running pressure that is the working pressure of the travel motor. It is configured to be controlled by a pattern.

  (I) The communication path is unconditionally closed during a fine travel operation with a small travel operation amount.

  (II) During a large travel operation with a large travel operation amount, the communication path is opened when the work pressure is higher than the travel pressure, and the communication path is closed when the work pressure is lower than the travel pressure.

  According to a second aspect of the present invention, in the configuration of the first aspect, the communication passage is closed unconditionally in a state where the traveling straight valve is switched to the traveling straight position.

  According to a third aspect of the present invention, in the configuration of the first or second aspect, the control valve is configured as a hydraulic pilot valve, and working pressure is introduced into one pilot chamber of the control valve, and traveling pressure is introduced into the pilot chamber on the opposite side. It is configured.

  According to a fourth aspect of the present invention, in the configuration of the third aspect, a communication path and a sub spool are provided in a main spool which is a spool of a travel straight valve, a pilot chamber is formed on both sides of the sub spool, and the main spool is formed. A control valve is configured by providing a working side pilot port for introducing working pressure into one pilot chamber and a traveling side pilot port for introducing running pressure into the opposite pilot chamber.

  According to the present invention, the control valve for opening and closing the communication path is provided, and this control valve closes the communication path unconditionally when the travel operation amount is small (half lever travel = low speed travel). The following effects are obtained because the communication path is opened when the working pressure is higher than the traveling pressure and the communication path is closed when the working pressure is higher than the traveling pressure during a large travel operation with a large operation amount (during full lever travel = high speed travel). Can be obtained.

  (1) During the half-lever travel, there will be no adverse effects such as the work-side oil flowing into the travel side to increase the speed, or the travel-side oil flowing into the work side to further decelerate or stop the travel. .

  (2) In a situation where the working pressure is higher than the running pressure during full lever running, the working side oil is supplied to the running side as intended, so that sudden deceleration can be prevented. However, in the opposite situation, since the oil flow on the traveling side and the working side is blocked, it is possible to prevent the adverse effect of more rapid deceleration.

  Thus, the communication path can be controlled to a desired state (open or closed state) according to the situation, and the combined operability can be improved.

  According to the second aspect of the present invention, since the traveling independent function is obtained in which the traveling operation is completely independent of the work operation at the straight traveling position, for example, it is possible to prevent the swinging of the load during traveling.

  Furthermore, according to the inventions of claims 3 and 4, the control valve is configured as a hydraulic pilot valve, and the working pressure is introduced into one pilot chamber of the control valve and the running pressure is introduced into the pilot chamber on the opposite side. Therefore, the control valve can be opened and closed automatically during full lever travel and accurately according to the working pressure and travel pressure.

  By the way, as a method for realizing the configuration of claim 3, it is possible to provide a control valve by pulling out the communication path to the outside of the straight traveling valve, and to operate this control valve as described above.

  However, according to this external control valve method, since a control valve must be newly installed outside, adding a control circuit increases the cost significantly, and the control valve is limited within a limited space. Problems such as having to create space arise.

  In this regard, according to the invention of claim 4, a configuration in which a communication path and a sub spool are provided in a main spool that is a spool of a traveling straight valve, and working pressure and traveling pressure are introduced into both side pilot chambers of the sub spool, That is, since the control valve is built in the straight traveling valve, there is no need to add a space for the control valve and a control circuit. For this reason, it is easy to mount the control valve and the cost can be reduced.

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

  FIG. 1 shows the overall configuration of the hydraulic control apparatus. In FIG. 1, the same parts as those of the conventional hydraulic control apparatus shown in FIG.

  In the embodiment, the straight travel valve 32 has a neutral position (i) at the left end in the figure and a straight travel position (d) at the right end, and intermediate first and second positions (b) and (c), and two pump ports P1, P2. And a four-position four-port switching valve having two actuator ports A and B, which are switched by the secondary pressure of the electromagnetic proportional switching control valve 29 in response to a command from the controller 33 based on an operation signal or the like. Be controlled.

  That is, the straight travel valve 32 is set to the neutral position a when traveling / working is operated alone.

  In this state (first pressure oil supply state), the discharge oil of the first pump 25 passes through the passage P1-B of the straight valve 27 and is first, as in the neutral position A of the straight valve 27 in FIG. The oil discharged from the second pump 26 is directly supplied to the second group G2 to the group G1.

  On the other hand, when the travel independent switch 34 is operated, the travel straight valve 32 is switched to the travel straight travel position D.

  In this state (second pressure oil supply state), the discharge oil of the first pump 25 is supplied to the work actuators 6, 7, 8, 12 through the passage P1-A and the pressure oil supply pipe L of the straight valve 32. On the other hand, the oil discharged from the second pump 26 is distributed and supplied to both the traveling motors 10 and 11, and traveling straightness is ensured.

  Further, since the traveling system is completely separated from the working system and an independent traveling state is obtained, it is possible to prevent, for example, a load swing during suspended traveling.

  In this case, if the first pressure oil supply state is suddenly switched to the second pressure oil supply state, the amount of pressure oil supplied to both travel motors 10 and 11 is suddenly reduced and suddenly decelerated, causing a shock.

  As a countermeasure against this point, like the conventional straight valve 27, the straight valve 32 is provided with a communication passage 35 for supplying a part of the oil discharged from the first pump 25 to the traveling side.

  However, if the communication path 35 is always open, an undesired situation may occur depending on the relationship between the working pressure and the traveling pressure during the half lever traveling and the full lever traveling as described above.

  Therefore, a control valve 36 for opening and closing the communication path 35 is incorporated in the straight running valve 32.

  2 (a) to 2 (d) show the configuration of the straight valve 32 with the control valve 36 in an enlarged manner for each position A to D as a hydraulic symbol.

  FIG. 3 shows a specific valve structure (half section) of the straight valve 32. As shown in the figure, a sub spool 38 is provided in a main spool 37, which is a spool of the straight valve 32, in a state where the stroke can be operated in the left-right direction in the figure.

  As shown in the figure, the sub spool 38 has a smaller diameter than the left and right end portions (the left and right end portions in FIG. 3; the same applies to the left and right direction of each portion described below). A communication path 35 is formed between the inner peripheral surface of 37. Reference numerals 39 and 40 are communication ports for communicating the communication path 35 with the pump ports P1 and P2.

  In addition, a work side pilot chamber 41 is provided on the right side of the sub spool 38 and a travel side pilot chamber 42 is provided on the left side, and work pressure (pressure of the first pump 25) is introduced into the work side pilot chamber 41 into the main spool 37. Work side pilot ports 43 and 44 and a travel side pilot port 45 for introducing a travel pressure (pressure of the second pump 26) into the travel side pilot chamber 42 are provided. In FIG. 3, Tp is a tank port and Dr is a drain port.

  The two working side pilot ports 43 and 44 are provided in the working side pilots in the neutral state of the straight valve in FIGS. 2 and 3 (a) and in the half lever traveling operation state in the combined operation of FIG. 2 (b). This is because the chamber 41 communicates with the tank port Tp or the drain port Dr, while the pilot chamber 41 communicates with the pump port P1 in the full lever traveling operation state of FIG.

  46 is a spring provided in the traveling side pilot chamber 42, and the sub spool 38 is moved in the right direction of FIG. 3 (reamed) by a force obtained by combining the force of the spring 46 and the traveling pressure introduced into the traveling side pilot chamber 42. It is pushed in the direction of closing the passage 35 and pushed in the left direction (the opening direction) by the working pressure introduced into the work side pilot chamber 41.

  In this way, the control valve 36 is constituted by the sub spool 38, the pilot chambers 41 and 42 on both sides, the pilot ports 43 to 45, the spring 46, and the like. Opening / closing control is performed as follows according to the running pressure.

  When the straight valve 32 is in the neutral position a, as shown in FIG. 3 (a), the work side pilot chamber 41 communicates with the tank and drain ports Tp, Dr, and the travel side pilot chamber 42 has a travel side pilot port. Communicating with the travel side pump port P2 through 45.

  Accordingly, since pressure (traveling pressure) is introduced only into the traveling-side pilot chamber 42, the sub spool 38 is pushed to the right and the communication path 35 (control valve 36) is closed. For this reason, between the two pump ports P1 and P2, the first pressure oil in which the discharge oil of the first pump 25 is supplied separately to the first group G1 and the discharge oil of the second pump 26 is supplied separately to the second group G2. Supply state.

  When a composite operation is performed from this state, the state shifts to the state shown in FIG. 3B or 3C depending on the travel operation amount.

  First, in the half lever travel stage in which the travel operation amount is small, as shown in FIG. 3B, the work side pilot chamber 41 communicates with the drain port Dr, and the travel side pilot chamber 42 passes through the travel side pilot port 44 to the pump port P2. Therefore, the communication path 35 is still closed.

  That is, when the half lever travels, the communication path 35 is unconditionally closed regardless of the working pressure and the traveling pressure.

  Therefore, when the working pressure is higher than the traveling pressure, the oil discharged from the first pump 25 flows into the traveling side and is accelerated against the operator's intention to travel at a low speed. When the pressure is higher than the working pressure, it is possible to prevent an undesired situation in which the oil discharged from the second pump 26 (running side oil) flows into the working side and the running is further decelerated or stopped.

  Next, when the full lever traveling operation is performed with the intention of traveling at a high speed from the half lever traveling state, traveling pressure is introduced into the traveling side pilot chamber 42 as shown in FIG. The working pressure is introduced into the working side pilot chamber 41 through the pump port P1 and the working side pilot port 43, and the position of the sub spool 38 is determined by the antagonistic action of the pressures of the pilot chambers 41 and 42 on both sides.

  That is, if the traveling pressure is higher than the working pressure, the sub spool 38 is pushed to the right side. Conversely, if the running pressure is lower than the working pressure, the sub spool 38 is pushed to the left side. Closes when higher and opens when lower.

  Thus, since the communication path 35 opens in a situation where the traveling pressure is low, a part of the oil on the work side is supplied to the traveling side as the original purpose for which the communication path 35 is provided, thereby preventing sudden deceleration of the traveling. it can.

  On the other hand, since the communication path 35 is closed in a situation where the traveling pressure is higher, it is possible to prevent the adverse effect that traveling-side oil turns to the working side and decelerates more rapidly.

  When the travel straight valve 32 is switched to the travel straight travel position D by the ON operation of the travel independent switch 34 shown in FIG. 1, the flow path of the pump discharge oil is P1-A, P2 as shown in FIG. 3 (d). At the same time as switching to -B, the communication path 35 is blocked, and the vehicle travels straight (travel independent state).

  In this way, the flow of oil during composite operation is controlled by controlling the opening and closing of the communication path 35 with the control valve 36 in accordance with the situation (separate half lever travel and full lever travel, and working pressure and travel pressure during full lever travel). It is possible to improve the composite operability.

  Moreover, a configuration in which the control valve 36 is built in the traveling straight valve 32, that is, a main spool 37 that is a spool of the traveling straight valve 32, a communication path 35 and a sub spool 38 that opens and closes the communication path 35 are provided. Since the sub-spool 38 is operated by the working pressure and the traveling pressure, it is not necessary to add a control valve space and a control circuit. For this reason, it is easy to mount the control valve 36 and the cost can be reduced.

Other Embodiments As shown in FIG. 4, the pilot ports 43 and 45 that connect the pilot chambers 41 and 42 to the pump ports P1 and P2 in the full lever traveling state at the time of combined operation are respectively provided with a throttle, Pilot ports 47 and 48 with a throttle leading to the tank port Tp may be added to both the traveling side.

  In this way, the pressure generated in the pilot chambers 41 and 42 on both the working side and the traveling side can be arbitrarily set according to the throttle sizes of the two pilot ports 43, 47 and 45, 48. There are advantages in that the degree of freedom of size selection for the spring 46 is widened and the pilot pressure on both sides can be stabilized.

  The two-stage throttle pilot structure may be provided only on one of the working side and the traveling side.

It is a figure showing the whole oil pressure control device composition concerning an embodiment of the present invention. (a)-(d) is a figure which shows the switching condition of the driving | running | working rectilinear valve in the apparatus as a hydraulic symbol. (a)-(d) is a half section drawing which shows the structure and switching state of the valve. It is half sectional drawing which shows the structure of the driving | running | working rectilinear valve concerning other embodiment of this invention. It is a schematic side view of a hydraulic excavator. It is a figure which shows the whole structure of the conventional hydraulic control apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lower traveling body 2 Upper revolving body 9 Work attachment 6, 7, 8, 12 Work actuator 10,11 Traveling motor G1 1st group G2 2nd group 25 1st pump 26 2nd pump 32 Traveling straight valve 35 Communication path 36 Control Valve 37 Main spool of travel straight valve 38 Sub spool 41 Work side pilot chamber 42 Travel side pilot chamber 43, 44 Work side pilot port 45 Travel side pilot port 46 Spring

Claims (4)

A work attachment is mounted on the upper swinging body mounted on the lower traveling body, and a hydraulic actuator group including a work actuator for operating the work attachment and left and right traveling motors includes either a left or right traveling motor. It is divided into a group and a second group including the other traveling motor, and both first and second pumps as hydraulic sources and a traveling straight valve for switching the flow path of pump discharge oil are provided. The valve is in a neutral position during a single operation for separately performing a traveling operation and a work operation, supplying the pump discharge oil to the first and second groups separately, and during a combined operation for simultaneously performing the traveling operation and the work operation. It is configured to switch to the straight travel position and supply the oil discharged from the separate pumps to both the travel motor and the work actuator, and the travel In a hydraulic control device for a work machine configured to connect the pump lines of both pumps through a communication path in the process of switching the straight valve from the neutral position to the traveling straight position, a control valve that opens and closes the communication path is provided. During operation, the control valve is controlled by the following pattern according to the position of the traveling straight valve, the working pressure that is the working pressure of the work actuator, and the running pressure that is the working pressure of the running motor. A hydraulic control device for a work machine, characterized by comprising.
(I) The communication path is unconditionally closed during a fine travel operation with a small travel operation amount.
(II) During a large travel operation with a large travel operation amount, the communication path is opened when the work pressure is higher than the travel pressure, and the communication path is closed when the work pressure is lower than the travel pressure.   2. The hydraulic control device for a working machine according to claim 1, wherein the communication path is unconditionally closed in a state in which the travel straight valve is switched to the travel straight travel position.   3. The hydraulic control device for a work machine according to claim 1, wherein the control valve is configured as a hydraulic pilot valve, and the working pressure is introduced into one pilot chamber of the control valve and the traveling pressure is introduced into the pilot chamber on the opposite side. A hydraulic control device for a work machine, characterized by comprising.   4. The hydraulic control device for a work machine according to claim 3, wherein a communication path and a sub spool are provided in a main spool which is a spool of a travel straight valve, a pilot chamber is formed on both sides of the sub spool, and the main spool is provided. The working machine hydraulic pressure is characterized in that a control valve is configured by providing a working side pilot port for introducing working pressure into one pilot chamber and a traveling side pilot port for introducing running pressure into the opposite pilot chamber. Control device.

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