JP4168004B2 - Hydraulic control equipment for construction machinery - Google Patents

Description

  The present invention relates to a hydraulic control device for a construction machine.

  A construction machine such as a hydraulic excavator is provided with an attachment such as a boom, an arm, or a bucket, and a traveling system for traveling independently. Many of the hydraulic control devices for construction machines that have been generally employed in the past have pump lines basically divided into two groups.

  In this type of hydraulic control device, one of the left and right, for example, a left traveling motor (traveling actuator) and an actuator for attachment other than traveling, such as a swing motor or an arm cylinder, are connected to one pump line. The other pump line is connected with a right traveling motor and other actuators for attachment other than traveling, such as a boom cylinder and a bucket cylinder.

  In the same pump line, each actuator is connected in parallel to the hydraulic pump via a direction switching valve (control valve).

  During normal work, since long running is hardly performed, with this configuration, various attachment operations that occupy most of the work can be performed using the two pump lines to the maximum.

  On the other hand, in the case of the connection mode in which the left and right travel actuators are distributed to the two pump lines, the pressure load in the left and right pump lines can be greatly different depending on the work state of the attachment. You may not be able to go straight ahead. Therefore, for example, when the traveling operation and the attachment operation are performed simultaneously, the traveling straight valve is switched, both the left and right traveling actuators are connected to only one pump line, and the actuator for the attachment other than the traveling There has been proposed a hydraulic control apparatus configured to switch the entire connection mode so that all of the above are connected to the other pump line (see, for example, Patent Document 1).

  According to the hydraulic control device according to this configuration, it is possible to ensure good straight traveling performance while performing each attachment work, regardless of the pressure load caused by the attachment work.

JP-A-3-244721

  However, in a hydraulic control apparatus that employs a configuration that switches the left and right traveling actuators to be driven by the same pump line when a predetermined condition is established in this way, Although there is an advantage that good straight traveling performance can be ensured regardless of the work load of the attachment, there has been a new problem that it may be difficult to escape from the mud.

  The present invention has been made as a result of ascertaining the causal relationship that such a problem is further promoted because the left and right traveling systems are combined into the same pump line, and is a normal attachment work. It is an object of the present invention to provide a hydraulic control device for a construction machine that secures a comfortable workability, ensures a good straight traveling property during traveling, and is easy to escape from a muddy or the like.

The present invention connects one of the left and right traveling actuators to the first pump line and a part of the actuator other than the traveling, and also connects the other left and right traveling actuators to the second pump line. In addition to having a first connection mode for connecting an actuator and other actuators other than traveling, when a predetermined condition is met , both the left and right traveling actuators are connected to the first pump line, and the second In the hydraulic control device for a construction machine configured to switch to the second connection mode in which all the actuators other than for driving are connected to the pump line, an idling detecting means for detecting the idling state of either the left or right traveling system is provided. provided, when the hydraulic control device of the construction machine, make any attachment operations other than the running with the traveling operation simultaneously, the first connection Rutotomoni switched from like the second connection mode, during operation in said second connection mode, when the idling detection means detects the idling state of the traveling system, switching to return to the first connection mode By providing the valve, the above-described problems are solved.

Due to the nature of construction machinery, it is often necessary to work on muddy land, so it is very often the case that either the left or right traveling system slips during traveling. In such a situation, the situation on the site is different each time, so it was difficult to think about the relationship with the hydraulic control device. However, when the left and right traveling systems are combined into the same pump line, good straight traveling performance can be obtained regardless of other attachment work on roads or construction sites where normal traveling is possible. However, when one of the traveling systems enters a mud and enters an idle state, the idle side becomes a low load, so that the pressure oil gradually flows into the low load side, making it difficult to escape.

  Therefore, in the present invention, when the left and right traveling actuators are connected in a single pump line by switching to the second connection mode in this way, the idling state is detected by some method. In addition, when it is detected that the idling state has occurred, the original first connection mode, that is, the connection mode in which the left and right travel actuators are distributed to separate pump lines is restored. As a result, the relative interference between the traveling actuators is cut off, and the pressure oil can be supplied to the traveling system on the high load side, so that the escape from the muddy can be performed more easily.

  Since the present invention uses the existing configuration of returning the existing straight traveling valve almost as it is, it is possible to obtain a great effect of “easy escape from mud” with only a slight modification.

  According to the present invention, it is possible to obtain a hydraulic control device for a construction machine that ensures a good straight traveling property during traveling while ensuring comfortable workability of a normal attachment work, and that is easy to escape from a muddy state. be able to.

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

  FIG. 1 is a schematic hydraulic circuit diagram showing the gist of the hydraulic control apparatus according to the present embodiment, and FIGS. 2 and 3 are more specific hydraulic circuit diagrams of FIG. 2 and 3, the same hydraulic circuit is divided into two for the convenience of the size of the page, and they are connected by C1 to C4 in the drawings.

  The schematic hydraulic circuit diagram of FIG. 1 is a schematic representation for explaining the main functions related to the present embodiment. What is an actual concrete hydraulic circuit shown in FIGS. It does not necessarily correspond one-on-one. Therefore, for convenience of explanation, the configuration of the present embodiment will be described here mainly with reference to FIG. 1, and in FIG. 2 and FIG. 3, the same reference numerals as those in FIG.

  In FIG. 1, the hydraulic control device 10 includes a front pump 12, a rear pump 14, and a pilot pump 16.

  The hydraulic control apparatus 10 includes a left traveling motor 20 operated by a left traveling control valve 18 and a right traveling motor 24 operated by a right traveling control valve 22 as a traveling system actuator. In addition, the hydraulic control device 10 includes, as actuators other than the traveling system, a bucket cylinder 28 operated by a bucket control valve 26, a boom cylinder 32 operated by a boom control valve 30, and an arm cylinder operated by an arm control valve 34. 36 and a turning motor 40 operated by a turning control valve 38.

  Each control valve 18, 22, 26, 30, 34, 38 shuts off or controls switching of the signal hydraulic line in conjunction with switching of each main controller 18A, 22A, 26A, 30A, 34A, 38A. Auxiliary control units 18B, 22B, 26B, 30B, 34B, and 38B are integrally provided.

  Each actuator is connected to the front pump 12 and the rear pump 14 via a travel straight valve 50 except for the right travel switching valve 22 directly connected to the front pump 12.

  The straight travel valve 50 includes switching positions A and B, and is always urged toward the switching position A by a spring 52. When the pilot line pressure P1 is input to the port 54 (overcoming the urging force of the spring 52), the traveling straight valve 50 is switched to the switching position B side, and further to the port 56 from an electromagnetic switching valve 58 (described later). When the pilot line pressure P2 is input, even if the pilot line pressure P1 is applied to the port 54, the switching position A can be returned.

  When the switching position of the traveling straight valve 50 is on the A side, a first connection mode is formed in which the left and right traveling motors 20 and 24 are distributed to the two pump lines of the front pump 12 and the rear pump 14, respectively. Further, when a predetermined condition described later is satisfied, the switching position is set to the B side, both the left and right traveling motors 20 and 24 are connected to the front pump 12, and all other actuators are connected to the rear pump 14. A second connection mode to be connected is formed.

  More specifically, when the straight travel valve 50 is set to the switching position A, the right travel control valve 22 (right travel motor 24) is connected to the front pump 12 via the line 60, and the line 62, The swing control valve 38 (swing motor 40) and the arm control valve 34 (arm cylinder 36) are respectively connected through 64. The left travel control valve 18 (left travel motor 20) is connected to the rear pump 14 via lines 66 and 68, and the bucket control valve 26 (bucket cylinder 28) and boom control are connected via lines 66 and 70. Valves 30 (boom cylinders 32) are connected to each other. This is the first connection mode in this embodiment.

  On the other hand, when the straight travel valve 50 is set to the switching position B, the right travel switching valve 22 (right travel motor 24) is connected to the front pump 12 via the line 60, and via the lines 62 and 68. The left travel control valve 18 (left travel motor 20) is connected to each other. Further, the bucket control valve 26 (bucket cylinder 28) and the boom control valve 30 (boom cylinder 32) are connected to the rear pump 14 through lines 66 and 70, and the swing control valve is connected through the lines 66 and 64. 38 (swing motor 40) and arm control valve 34 (arm cylinder 36) are connected to each other. This is the second connection mode in this embodiment.

  The pilot line pressure P1 at the port 54 of the straight travel valve 50 is such that one of the left and right travel control valves 18, 22 is turned on, and one of the other actuator control valves 26, 30, 36, 40 is on. Occurs when a state is entered. The oil passage for specifically generating the pilot line pressure P1 is constituted by auxiliary control portions 18B, 22B, 26B, 30B, 34B, 38B, etc. of the respective control valves (see FIG. 2). Since the first and second connection modes themselves belong to a known connection mode, detailed description thereof is omitted here.

  On the other hand, the pilot line pressure P <b> 2 of the port 56 of the traveling straight valve 50 is generated by the electromagnetic switching valve 58. The electromagnetic switching valve 58 is maintained on the X side by a spring 58A during normal times (when not excited), and connects the port 56 to the tank T. However, when a predetermined condition is satisfied (when the idling state of the traveling system is detected in the second connection mode), the operation is switched to the Y side, and the pilot line pressure P2 of the pilot pump 16 is guided to the port 56 side. It is said that.

  In the present embodiment, in order to determine whether this predetermined condition is satisfied, a pressure switch 80 for detecting the operation of the left and right travel control valves 18 and 22 and a pressure switch 82 for detecting the operation of other actuators are provided. And the pressure sensor 84 is arrange | positioned at the pump line 60 to which the traveling system is connected in the pump line of the front side, ie, the 2nd connection mode.

  With this configuration, when both the pressure switches 80 and 82 are turned on, that is, when either the traveling system or another actuator is operated at the same time and the line pressure Po of the traveling system line 60 is determined to be less than or equal to a predetermined value. In addition, a control configuration is formed in which the electromagnetic switching valve 58 is excited, the electromagnetic switching valve 58 is switched to the Y side, and the pilot line pressure P2 is guided to the port 56 of the traveling straight valve 50.

  Next, the operation of this embodiment will be described.

  When the normal work inherent to the construction machine is performed, the line pressure P1 is not particularly generated at the port of the traveling straight valve 50, so that the traveling straight valve 50 maintains the switching position A side by the urging force of the spring 52. As a result, the first connection mode is formed.

  That is, the right travel control valve 22 (right travel motor 24) is connected to the front pump 12 through a line 60, and the swing control valve 38 (swing motor 40) and the arm control valve are connected through lines 62 and 64. 34 (arm cylinder 36) are respectively connected. The left travel control valve 18 (left travel motor 20) is connected to the rear pump 14 via lines 66 and 68, and the bucket control valve 26 (bucket cylinder 28) and boom control are connected via lines 66 and 70. Valves 30 (boom cylinders 32) are connected to each other.

  Thus, the frequently used actuator groups of the bucket cylinder 28 and the boom cylinder 32 and the actuator groups of the arm cylinder 36 and the swing motor 40 are respectively driven by separate (two) pump lines. Will be able to work comfortably.

  Even when one or both of the left and right traveling motors 20, 24 are driven, the line pressure P1 at the port 54 of the traveling straight valve 50 is not generated unless any other actuator is simultaneously driven at this time. Therefore, the first connection mode is maintained as it is.

  Here, when both the left and right traveling control valves 18 and 22 are turned on and any other actuator is operated at the same time, the line pressure P1 is generated at the port 54 of the traveling straight valve 50. The straight valve 50 is switched to the B side, and the second connection mode is formed.

  That is, the right travel switching valve 22 (right travel motor 24) is connected to the front pump 12 via a line 60, and the left travel control valve 18 (left travel motor 20) is connected via lines 62 and 68, respectively. Connected. Further, the bucket control valve 26 (bucket cylinder 28) and the boom control valve 30 (boom cylinder 32) are connected to the rear pump 14 through lines 66 and 70, and the swing control valve is connected through the lines 66 and 64. 38 (swing motor 40) and arm control valve 34 (arm cylinder 36) are connected to each other.

  Accordingly, the left and right traveling motors 20 and 24 can be independently supplied with the pressure oil from the front pump 12 regardless of the usage mode of the actuator other than traveling, and good traveling straightness can be ensured.

  By the way, when traveling in this state, if one of the traveling systems becomes muddy and falls into the idling state, the traveling load of the idling state suddenly becomes lighter. The supplied pressure oil will increasingly flow into the light load side travel system. As a result, idling tends to become more intense and it becomes difficult to escape from the mud. However, in this embodiment, this state can be detected by the pressure switches 80 and 82 and the pressure sensor 84, and the connection mode can be returned to the first connection mode.

  First, it is determined whether or not both of the pressure switches 80 and 82 are on. This is for confirming whether or not the current state is operating in the second connection mode. If the operation is not performed in the second connection mode, the problem of “difficult to escape from mud” noted in the present embodiment is not particularly problematic. When it is determined that both the pressure switches 80 and 82 are in the ON state and the pressure sensor 84 determines that the pressure of the system of the front pump 12 serving as the traveling system is equal to or lower than a predetermined value, the electromagnetic switching valve 58 is excited. And switched to the Y side. This is because the driving pressure for traveling is not so high originally, but when the idling starts, the load further decreases suddenly, so that the idling state is detected by detecting that the pressure of the system of the front pump 12 is below a predetermined value. This is because it is considered that it can be detected.

  By switching the electromagnetic switching valve 58 to the Y side, the pilot line pressure P2 generated by the pilot pump 16 acts on the port 56 of the traveling straight valve 50, and the traveling straight valve 50 is pushed back to the switching position A side. Then, the hydraulic control apparatus 10 is again in the first connection mode, and the left and right traveling motors 20 and 24 are separately driven by the rear pump 14 and the front pump 12, respectively. Therefore, it becomes possible to supply pressure oil to the traveling high load side (side not idling), and it is easy to escape from the mud.

  Here, if the state is kept as it is, the pressure sensor 84 has recovered to a predetermined value or more because it may cause meandering (because of the first connection mode) after escape from the muddy state. Is detected, the electromagnetic switching valve 58 is turned off again to return to the second connection mode (for straight traveling). Note that the predetermined value in this case is set slightly higher than the predetermined value when idling is detected in order to prevent hunting.

  Various variations are conceivable for the present invention.

  In the above embodiment, basically, one of the left and right traveling actuators and the non-traveling actuator are connected to the first pump line, and the other of the left and right is connected to the second pump line. The travel actuator and other actuators other than the travel were connected (first connection mode). In this state, when the traveling operation and any attachment operation other than traveling are performed at the same time, both the left and right traveling actuators are connected to the first pump line, and the traveling operation is performed with respect to the second pump line. It was set as the structure by which all actuators other than are connected and connected (2nd connection aspect).

However, according to the present invention, from the gist, the hydraulic control device has at least two connection modes. From the first connection mode in which the left and right travel actuators are distributed to the two pump lines, The present invention can be similarly applied as long as it can be switched to the second connection mode in which both the left and right traveling actuators are combined in the pump line .

  Moreover, in the said embodiment, it is provided with the driving | running | working system pressure detection means which detects the pressure of the pump line by which the actuator for driving | running | working is connected in the 2nd connection aspect among two pump lines, A configuration has been adopted in which the electromagnetic switching valve is switched when the idling state is detected when the pressure detected by the detection means is equal to or lower than a predetermined value.

  However, in the present invention, how to specifically detect the idling state of the left and right traveling systems is not particularly limited. For example, in addition to the above-described detection method, pressure detection means (for example, the aforementioned pressure sensor 84) that detects the pressure of one of the two pump lines, and pressure detection means that detects the pressure of the other pump line (For example, a sensor denoted by reference numeral 88 in FIG. 1), and when the differential pressure between the pressures detected by the two pressure detection means (the difference between the pressures detected by the pressure sensors 84 and 88) exceeds a predetermined value, It can also be set as the structure which switches a switching valve as a state is detected.

  Furthermore, left and right traveling system pressure detecting means (for example, sensors 90 and 92 in FIG. 1) that respectively detect the pressure actually applied to the left and right traveling actuators are provided. A configuration may be adopted in which the switching valve is switched when the idling state is detected when the differential pressure between the respective detected pressures becomes a predetermined value or more.

  Alternatively, the idling state may be detected more accurately by appropriately combining these configurations. In addition, when it transfers to the 2nd connection mode from the 1st connection mode under specific conditions, the idling state detection on the assumption of the specific conditions should be made.

  In the above embodiment, the fact that the idling state has been detected is detected by the output signal of the pressure detection means such as a pressure switch or a pressure sensor, and the traveling straight valve is switched via the switching valve (58). . This method is excellent in that the degree of freedom of switching control is high and the idling state can be detected in detail based on various information. However, in the present invention, a hydraulic pressure corresponding to the pilot line pressure P2 is mechanically generated from a hydraulic line having similar information using a throttle, a check valve, a switching valve, or the like, and this is generated as a straight travel valve (50). It may be guided to the port (56). In this case, the detection of the idling state is not detected as “substantiated information” per se, but the information extracted as pilot hydraulic pressure on such a predetermined hydraulic line can also be used as the predetermined effect of the present invention. It can be the detection information of the idling state for extracting.

  Further, the present invention basically relies on the detection of the idling state to return from the second connection mode to the first connection mode, and (when the idling has converged) There are no particular restrictions on the conditions for transitioning to the second connection mode, but at this time, if the configuration for applying the conditions for transitioning from the first connection mode to the second connection mode is applied as it is, There is a possibility of returning to the second connection mode before the idling state is not yet settled.

  Therefore, it is preferable to separately provide a means for detecting that the idling state has converged and to return to the second connection mode again on condition that the idling state has been detected.

  In this case, as to how to detect that the idling state has converged, for example, as in the previous embodiment, the configuration for idling detection is changed by changing the threshold (giving hysteresis) and detecting convergence. It may be used again as a configuration for the above, or may be configured to detect that the elapsed time after switching to the first connection mode has become a predetermined time or more due to the detection of the idling state. . This belongs to the technique of giving temporal hysteresis to the return.

  INDUSTRIAL APPLICABILITY The present invention can be used as a hydraulic control device that facilitates escape of mud while a construction machine is traveling straight ahead.

1 is a schematic hydraulic circuit diagram schematically showing the gist of a hydraulic control device for a construction machine to which an example of an embodiment of the present invention is applied. Hydraulic circuit diagram showing half of a more specific configuration of the hydraulic control device Hydraulic circuit diagram showing the other half of the more specific configuration of the hydraulic control device

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Hydraulic control apparatus 12 ... Front pump 14 ... Rear pump 16 ... Pilot pump 18 ... Left travel control valve 20 ... Left travel motor 22 ... Right travel control valve 24 ... Right travel motor 26 ... Bucket control valve 28 ... Bucket cylinder 30 ... Boom Control valve 32 ... Boom cylinder 34 ... Arm control valve 36 ... Arm cylinder 38 ... Swing control valve 40 ... Swing motor 50 ... Traveling straight valve 52 ... Spring 54, 56 ... Port 58 ... Electromagnetic switching valve 58A ... Spring 60, 62, 64 , 66, 68, 70 ... line 80, 82 ... pressure switch 84, 88 ... pressure sensor T ... tank

Claims (6)

One of the left and right traveling actuators and a part of the actuator other than traveling are connected to the first pump line, and the other left and right traveling actuators and other than the traveling are connected to the second pump line. a first connection mode connecting the other actuators, with connecting both the left and right traveling actuator on the first pump line to connect all actuators except for the traveling to the second pump line In the hydraulic control device for a construction machine having the second connection mode ,
Equipped with idling detection means for detecting idling state of either the left or right traveling system ,
Hydraulic control device for the construction machine, when performing any attachment operations other than the running with the travel operation time, Rutotomoni switched from the first connection mode to the second connection mode,
During operation in the second connection mode, when the idling detection means detects the idling state of the traveling system, for a construction machine characterized by comprising a switching valve to return to said first connection mode Hydraulic control device. Oite to claim 1, further
Of the two pump lines, a travel system pressure detecting means for detecting the pressure of the pump line to which the travel actuator is connected in the second connection mode is provided, and the detected pressure by the travel system pressure detecting means is predetermined. A hydraulic control device for a construction machine, wherein the switching valve is switched when the idling state is detected when a state equal to or less than a value is detected. Oite to claim 1, further
Of the two pump lines, in the second connection state, a traveling system pressure detecting means for detecting a pressure of a pump line to which a traveling actuator is connected and a pressure of a pump line to which an actuator other than the traveling is connected are detected. Attachment system pressure detecting means,
A configuration in which the changeover valve is switched when the idling state is detected when the pressure difference between the pressure detected by the traveling system pressure detecting means and the pressure detected by the attachment system pressure detecting means is greater than or equal to a predetermined value. This is a hydraulic control device for construction machinery. Oite to claim 1, further
Left and right traveling system pressure detecting means for respectively detecting the pressures of the pump line to which the traveling actuator is connected in the second connection state of the two pump lines. Prepared,
When the differential pressure between the detected pressures by the left and right traveling system pressure detecting means is in a state of a predetermined value or more, the switching valve is switched when the idling state is detected. Hydraulic control device for construction machinery. In any one of Claims 1-4 ,
Furthermore, a means for detecting that the idle state has converged,
The hydraulic control device for a construction machine, wherein the first connection mode is returned to the second connection mode again when it is detected that the idling state has converged. In claim 5 ,
Means for detecting that the idling state has converged,
A hydraulic control device for a construction machine, characterized in that it is means for detecting that an elapsed time after returning to the first connection mode when the idling state is detected is a predetermined time or more.

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