JP5272211B2 - Hydraulic circuit for construction machinery - Google Patents

Description

  The present invention relates to a hydraulic circuit of a construction machine such as a hydraulic excavator.

  The hydraulic excavator includes a plurality of operating parts such as a lower traveling body (base body), an upper swing body, a boom, an arm, and a bucket, and is widely used for construction work and the like.

  Often, these multiple actuation sites of a hydraulic excavator are actuated simultaneously. For example, when performing excavation work or floor digging work, which is a general work of a hydraulic excavator, simultaneous operation (combined operation) in which the boom and the arm are simultaneously operated is often performed. In order to perform such simultaneous operation smoothly, a plurality of hydraulic pumps are provided, and a boom switching valve and an arm switching valve are connected in tandem to each hydraulic pump, and the tandem connected passages are connected in parallel. A provided hydraulic circuit is used (for example, see Patent Document 1).

  An example of such a hydraulic circuit is the hydraulic circuit shown in FIG. The hydraulic circuit 100 includes a plurality of hydraulic pumps (first hydraulic pump 102 and second hydraulic pump 104) for driving hydraulic actuators in parallel. From the upstream to the downstream of the first hydraulic pump 102, the first boom switching valve 110 for adjusting the direction and flow rate of the driving hydraulic oil to the boom cylinder 106, and the driving hydraulic oil to the arm cylinder 108 An arm second switching valve 116 for adjusting the direction and flow rate is provided in tandem. Further, from the upstream side to the downstream side of the second hydraulic pump 104, the boom second switching valve 112 for adjusting the direction and flow rate of the driving pressure oil to the boom cylinder 106, and the driving pressure to the arm cylinder 108 are provided. An arm first switching valve 114 for adjusting the oil direction and flow rate is provided in tandem. Thereby, in the hydraulic circuit 100, the boom switching valve and the arm switching valve that are tandemly connected are tandemly connected to the hydraulic pumps 102 and 104 and provided in parallel.

  When excavation is performed by a hydraulic excavator equipped with the hydraulic circuit 100, the boom is raised at the same time as the operation lever 120A of the arm remote control lever device 120 in FIG. The operation is performed by appropriately adjusting the operation (performed by tilting the operation lever 118A of the boom remote control lever device 118 to the right in FIG. 5) and the bucket closing operation.

  At this time, the supply of pressure oil from the second hydraulic pump 104 to the arm cylinder 108 is performed by adjusting the opening degree of the tandem passage 130 according to the amount of switching from the neutral position of the second boom switching valve 112 to the position p, and the boom. When the boom raising input of the boom remote control lever device 118 is very small so that the boom operation can be performed reliably (this is done via the second switching valve 112 and the parallel passage 132 arranged in parallel). Even when the boom operation lever 118A is slightly tilted to the right in FIG. 5, the boom second switching valve 112 is set so that the opening degree of the tandem passage 130 is narrowed. FIG. 6 is a graph showing an example of the relationship between the switching amount from the neutral position to the position p side of the second boom switching valve 112 and the opening area of the tandem passage 130. For reference, the relationship with the opening area of the meter-in passage 134 is also shown in FIG. As shown in FIG. 6, even if the switching amount from the neutral position to the position p side of the second boom switching valve 112 is small, the opening area of the tandem passage 130 is greatly reduced, and the boom second switching valve 112 is When switching to the position p side by about one third of the movable range, the opening area of the tandem passage 130 is set to be about 10% when the second boom switching valve 112 is in the neutral position.

  On the other hand, the parallel passage 132 has a smaller passage area than the tandem passage 130 due to its structure, or a throttle 136 is provided on the passage to prevent excessive supply of pressure oil to the arm cylinder 108. The pressure oil supply is limited to some extent.

JP 2002-4339 A

  Here, in the early stage of excavation work, the earth and sand are basically collected by the movement of the arm 122, but the closing operation of the arm 122 adds a passage pressure loss to the pressure that needs to be applied to the arm cylinder bottom chamber for the arm closing operation. This can be achieved by applying a pressure to the arm cylinder bottom chamber passage 108a.

  On the other hand, in the early stage of excavation work, the operation for raising the boom 124 is performed simultaneously with the operation for closing the arm 122, but this boom raising operation is not intended to raise the boom 124 itself. This is to suppress the jack-up of the airframe caused by the excavation reaction force due to the arm operation. For this reason, the boom raising operation in the early stage of excavation work is an operation of controlling the extension amount of the rod of the boom cylinder 106 with respect to the force pulling the rod of the boom cylinder 106 (excavation reaction force due to the arm operation). This is based on meter-out control of the pressure oil returning from the rod chamber to the tank T.

  The meter-out passage 106a that leads from the rod chamber of the boom cylinder 106 to the tank T is installed only in the first boom switching valve 110 for simplification of the structure, and the merging meter-in passage 134 is connected to the second boom switching valve 112. Only the tandem passage 130 may be installed (for example, the hydraulic circuit shown in FIG. 5).

  Therefore, in the boom raising operation at the beginning of excavation work by the hydraulic excavator having the hydraulic circuit shown in FIG. 5, there is actually no pressure oil that returns to the tank T through the second boom switching valve 112 (second boom switching). Despite the fact that meter-out control is not performed on the pressure oil that returns to the tank T through the valve 112), the boom operation lever 118A is operated in the boom raising direction (the operation amount in the right direction in FIG. 5). Then, the meter-in control is performed, and the second boom switching valve 112 is switched to the position p side, and the tandem passage 130 of the second boom switching valve 112 following the first arm switching valve is throttled. For this reason, although the amount of pressure oil supplied to the boom cylinder 106 is not required so much, the passage pressure loss of the pressure oil supplied to the arm cylinder 108 increases as a result. The energy loss of the arm closing operation becomes large.

  This invention is made | formed in view of this problem, Comprising: It aims at providing the hydraulic circuit of the construction machine which can suppress the energy loss of arm closing operation | movement low.

  The present invention is connected to a first hydraulic pump, connected to a first switching valve for a boom for switching the direction and flow rate of pressure oil supplied to a boom cylinder that drives the boom, and a second hydraulic pump, A second switching valve for boom for switching the direction and flow rate of pressure oil supplied to the boom cylinder; and a tandem connection to the second hydraulic pump downstream from the second switching valve for boom; A first switching valve for arm for switching the direction and flow rate of pressure oil supplied to the arm cylinder to be driven, and the first hydraulic pump are connected in tandem with the first switching valve for boom and supplied to the arm cylinder. A second switching valve for the arm for switching the direction and flow rate of the pressurized oil, and a boom operation lever for operating the first switching valve for the boom and the second switching valve for the boom. In the hydraulic circuit of the machine, a boom second switching valve control mechanism capable of changing the degree of switching from the neutral position of the second boom switching valve to the operation amount of the boom operating lever is provided, and the arm closing From the neutral position of the second boom switching valve with respect to the operation amount of the boom operation lever, when the operation state and the boom raising operation are performed at the same time and in a specific work state that matches a predetermined condition The above-mentioned problem is solved by controlling the switching amount to be smaller than that in times other than the specific work state.

  In the present invention, the amount of switching from the neutral position of the second switching valve for the boom to the amount of operation of the boom operating lever is a working state in which the arm closing operation and the boom raising operation are performed simultaneously and meet a predetermined condition. In a specific work state to be controlled, control is performed to be smaller than in other than the specific work state. For this reason, the pressure oil supplied from the second hydraulic pump can be supplied to the bottom chamber of the arm cylinder in a state where the opening degree of the tandem passage is large, so that the passage pressure loss is reduced. Therefore, in the present invention, it is possible to perform the arm closing operation with little energy loss.

  Whether or not it is the specific work state is, for example, comparing at least one of the arm closing parameters indicating the degree of the closing operation of the arm with a predetermined threshold, and the boom raising parameter indicating the degree of the boom raising operation Can be determined by comparing at least one of the values with a predetermined threshold.

  In this case, a boom pilot pressure detecting means for detecting a pilot pressure for switching the first boom switching valve, a pilot pressure for switching the first arm switching valve, and a pilot pressure for switching the second arm switching valve. An arm pilot pressure detecting means for detecting at least one of the pilot pressure for switching the first switching valve for the arm or the pilot pressure for switching the second switching valve for the arm as one of the arm closing parameters. One of the boom raising parameters may be a pilot pressure for switching the first boom switching valve.

  Further, when an arm operating lever for operating the first arm switching valve and the second arm switching valve is provided, one of the arm closing parameters can be set as an operation amount of the arm operating lever. One of the boom raising parameters may be an operation amount of the boom operation lever.

  Also, a boom pressure oil amount detecting means for detecting the pressure oil amount supplied to the bottom chamber of the boom cylinder, and an arm pressure oil amount detecting means for detecting the pressure oil amount supplied to the bottom chamber of the arm cylinder. The one of the arm closing parameters can be the amount of pressure oil supplied to the bottom chamber of the arm cylinder, and one of the boom raising parameters can be supplied to the bottom chamber of the boom cylinder. The amount of pressure oil can be reduced.

  Further, whether or not the specific working state is present is based on the thrust when the arm cylinder rod is extended, when arm cylinder rod extension thrust detection means for detecting the thrust when the arm cylinder rod is extended is provided. It can also be judged.

  In the case of including discharge pressure detection means for detecting discharge pressures of the first hydraulic pump and the second hydraulic pump, whether or not the specific working state is present is determined by the first hydraulic pump and the second hydraulic pump. It can also be determined based on the discharge pressure of the hydraulic pump.

  In the case of including an excavation work determination means for determining whether the work state of the construction machine is an early stage of the excavation work, the work state of the construction machine is the early stage of the excavation work. It can also be determined based on whether or not.

  In the case of having a floor digging operation determining means for determining whether or not the work state of the construction machine is a floor digging work, whether the work state of the construction machine is a floor digging work or not is determined. Judgment can be made based on whether or not.

  According to the present invention, the energy loss of the arm closing operation can be suppressed low.

The figure which shows the structure of the hydraulic circuit of the hydraulic shovel which concerns on 1st Embodiment of this invention. In the hydraulic circuit, a graph schematically showing an example of the relationship between the switching amount from the neutral position of the second boom switching valve 18 to the position D side and the opening areas of the tandem passage 40 and the boom confluence passage 80c. The figure which shows the structure of the hydraulic circuit of the hydraulic shovel which concerns on 2nd Embodiment of this invention. The figure which shows the structure of the hydraulic circuit of the hydraulic shovel which concerns on 3rd Embodiment of this invention. The figure which shows an example of a structure of the hydraulic circuit of the conventional hydraulic shovel The graph which shows typically an example of the relationship between the switching amount from the neutral position of the 2nd switching valve 112 for booms to the position p side, and the opening area of the tandem channel | path 130 and the meter-in channel | path 134 in the hydraulic circuit of the conventional hydraulic shovel.

  Hereinafter, an example of a preferred embodiment of a hydraulic circuit of a hydraulic excavator according to the present invention will be described in detail based on the drawings.

  FIG. 1 is a diagram showing a configuration of a hydraulic circuit of a hydraulic excavator according to the first embodiment of the present invention.

  The hydraulic circuit 10 includes a first hydraulic pump 12, a second hydraulic pump 14, a boom first switching valve 16, a boom second switching valve 18, an arm first switching valve 20, and an arm first switching valve. 2 switching valve 22, boom remote control lever device 24, arm remote control lever device 26, pressure sensors 28 and 30, controller 32, electromagnetic proportional valve 34, and pilot hydraulic pump 36, and a boom cylinder Pressure oil is supplied to 80 and the arm cylinder 82, and the boom 84 and the arm 86 are actuated to cause the excavator 70 to perform various operations such as excavation work and floor digging work. Reference numeral 88 denotes a bucket.

  The first hydraulic pump 12 and the second hydraulic pump 14 are arranged in parallel. A tandem passage 38 is connected to the first hydraulic pump 12, and pressure oil supplied from the first hydraulic pump 12 via the tandem passage 38 is supplied to the boom cylinder 80 and / or the arm cylinder 82. The tandem passage 38 is provided with the boom first switching valve 16 on the upstream side and the arm second switching valve 22 on the downstream side. The boom first switching valve 16 and the arm second switching valve are provided. 22 is connected in tandem.

  A tandem passage 40 is connected to the second hydraulic pump 14, and pressure oil supplied from the second hydraulic pump 14 via the tandem passage 40 is supplied to the boom cylinder 80 and / or the arm cylinder 82. The tandem passage 40 is provided with the second boom switching valve 18 on the upstream side and the arm first switching valve 20 on the downstream side. The boom second switching valve 18 and the arm first switching valve are provided. 20 is connected in tandem.

  The first boom switching valve 16 is a three-position six-port switching valve, and includes three switching positions A, B, and C. The direction and flow rate of the pressure oil from the first hydraulic pump 12 toward the boom cylinder 80. To control. Pilot ports 16a and 16b are respectively provided at both ends of the spool of the first boom switching valve 16, and pilot pressure is supplied from the pilot passages 24a and 24b, respectively.

  The spool of the first boom switching valve 16 moves when the operator operates the boom remote control lever device 24 to control the direction and flow rate of the pressure oil supplied from the first hydraulic pump 12 to the boom cylinder 80. The pressure oil supplied from the first hydraulic pump 12 to the boom cylinder 80 is supplied from the tandem passage 38 to the boom cylinder 80 via the boom first switching valve 16 and the boom passages 80a and 80b.

  The second boom switching valve 18 is a three-position six-port switching valve, and has three switching positions D, E, and F. The direction and flow rate of pressure oil from the second hydraulic pump 14 toward the boom cylinder 80 To control. Pilot ports 18a and 18b are respectively provided at both ends of the spool of the second boom switching valve 18, and pilot pressure is supplied to the pilot port 18a from the pilot passage 36a. The pilot passage 36b is connected to the tank T, and no pilot pressure is supplied to the pilot port 18b.

  At the switching position D, the boom confluence passage (meter-in passage) 80c communicates, and the pressure oil from the second hydraulic pump 14 is supplied to the bottom chamber of the boom cylinder 80, but the boom cylinder 80 returns from the rod chamber. The passage through which oil passes is not provided at the switching position D. This is because there is not much return oil from the rod chamber of the boom cylinder 80, and the passage through which the return oil from the rod chamber of the boom cylinder 80 returns to the tank T is sufficient only for the passage through the first switching valve 16 for boom. That's why. Therefore, the entire amount of return oil from the rod chamber of the boom cylinder 80 returns to the tank T through the first boom switching valve 16.

  Similarly to the spool of the first boom switching valve 16, the spool of the boom second switching valve 18 is moved by the operator operating the boom remote control lever device 24, and supplied from the second hydraulic pump 14 to the boom cylinder 80. Control the direction and flow rate of pressurized oil. The pressure oil supplied from the second hydraulic pump 14 to the boom cylinder 80 passes from the tandem passage 40 through the boom second switching valve 18 to the boom junction passage 80c, and at the junction points 80e and 80f, the boom passages 80a and 80b. And are supplied to the boom cylinder 80. However, as will be described in detail later, the movement amount of the spool of the second boom switching valve 18 is determined only by the pilot pressure determined by the operation amount of the operation lever 24A of the boom remote control lever device 24 made by the operator. Instead, the controller 32 determines the pilot pressure determined by the operation amount of the operation lever 26A of the arm remote control lever device 26.

  The first arm switching valve 20 is a three-position six-port switching valve, and has three switching positions G, H, and I. The direction and flow rate of pressure oil from the second hydraulic pump 14 toward the arm cylinder 82 To control. Pilot ports 20a and 20b are respectively provided at both ends of the spool of the arm first switching valve 20, and pilot pressure is supplied from the pilot passages 26a and 26b, respectively.

  The spool of the arm first switching valve 20 moves when the operator operates the arm remote control lever device 26, and controls the direction and flow rate of the pressure oil supplied from the second hydraulic pump 14 to the arm cylinder 82. The pressure oil supplied from the second hydraulic pump 14 to the arm cylinder 82 passes from the parallel passage 42 or the tandem passage 40 and the parallel passage 42 through the arm first switching valve 20 and the arm passages 82a and 82b. It is supplied to the arm cylinder 82.

  The second arm switching valve 22 is a three-position six-port switching valve, and includes three switching positions J, K, and L. The direction and flow rate of pressure oil from the first hydraulic pump 12 toward the arm cylinder 82 To control. Pilot ports 22a and 22b are respectively provided at both ends of the spool of the arm first switching valve 22, and pilot pressure is supplied from the pilot passages 26a and 26b, respectively.

  Similarly to the spool of the arm first switching valve 20, the spool of the arm second switching valve 22 moves when the operator operates the arm remote control lever device 26, and the direction of the pressure oil supplied to the arm cylinder 82 And control the flow rate. The pressure oil supplied from the first hydraulic pump 12 to the arm cylinder 82 passes from the parallel passage 44 or the tandem passage 38 and the parallel passage 44 through the arm second switching valve 22 and through the arm joining passages 82c and 82d. At the joining points 82e and 82f, the arm passages 82a and 82b join together and are supplied to the arm cylinder 82.

  The pressure sensor (boom pilot pressure detecting means) 28 has a role of measuring the pilot pressure of the pilot passage 24a supplied to the pilot port 16a of the first boom switching valve 16, and the obtained pressure data is an electric signal. It is sent to the controller 32 via the line 28a.

  The pressure sensor (arm pilot pressure detecting means) 30 has a role of measuring the pilot pressure of the pilot passage 26b supplied to the pilot port 20b of the first arm switching valve 20, and the obtained pressure data is an electric signal. It is sent to the controller 32 via the line 30a.

  Based on the pressure data sent from the pressure sensors 28 and 30, the controller 32 determines whether or not the working state of the excavator 70 corresponds to the early stage of excavation work (specific working state), and based on the determination result. The electromagnetic proportional valve 34 is operated via the electric signal line 32a to adjust the opening degree of the pilot passage 36a, and the pilot pressure supplied from the pilot hydraulic pump 36 to the pilot port 18a of the second boom switching valve is adjusted. Thus, the switching amount from the neutral position to the position D side of the second boom switching valve 18 is adjusted. Therefore, the controller 32, the electromagnetic proportional valve 34, and the pilot hydraulic pump 36 can be said to be a second boom switching valve control mechanism.

  The electromagnetic proportional valve 34 receives a command from the controller 32, adjusts the opening degree of the pilot passage 36a, adjusts the pilot pressure supplied to the pilot port 18a of the second boom switching valve 18, and controls the second boom valve. It has the role of adjusting the switching amount from the neutral position to the position D side of the switching valve 18. When an electric signal is sent from the controller 32 to the solenoid portion 34a of the electromagnetic proportional valve 34 via the electric signal line 32a, the electromagnetic proportional valve 34 switches the spool of the electromagnetic proportional valve 34 in accordance with the electric signal, and the pilot passage 36a Adjust the opening. As a result, the pilot pressure supplied to the pilot port 18a of the second boom switching valve 18 is adjusted, and the switching amount from the neutral position to the position D side of the second boom switching valve 18 is adjusted.

  Next, the operation and action of the hydraulic circuit 10 according to the first embodiment configured as described above will be described.

  In FIG. 1, when the operator tilts the operation lever 24A of the boom remote control lever device 24 to the right and applies pilot pressure to the pilot port 16a via the pilot passage 24a, the first boom switching valve 16 is moved to the position A. The second boom switching valve 18 is switched to the position D (however, as will be described later, the switching amount from the neutral position to the position D side is limited by the control of the controller 32 in the early stage of excavation work). . Thereby, the pressure oil from the first hydraulic pump 12 is supplied to the bottom chamber of the boom cylinder 80 via the tandem passage 38 and the boom passage 80a, and the pressure oil from the second hydraulic pump 14 is supplied to the tandem passage 40 and the boom. It is supplied to the bottom chamber of the boom cylinder 80 through the junction passage 80c, the junction 80e, and the boom passage 80a. Thereby, the rod of the boom cylinder 80 extends and the boom 84 rises.

  At this time, the pressure sensor 28 measures pilot pressure data (pilot pressure data applied to the pilot port 16a) of the pilot passage 24a, and sends the measured pilot pressure data to the controller 32 via the electric signal line 28a.

  In addition, when the operator tilts the operation lever 26A of the arm remote control lever device 26 to the left in FIG. 1 and applies pilot pressure to the pilot ports 20b and 22b via the pilot passage 26b, the arm first switching valve 20 is provided. Is switched to position I, and the second arm switching valve 22 is switched to position L. Thus, the pressure oil from the second hydraulic pump 14 passes from the parallel passage 42 or the tandem passage 40 and the parallel passage 42 through the arm first switching valve 20, the arm passage 82 b, and the bottom of the arm cylinder 82. The pressure oil supplied to the chamber from the first hydraulic pump 12 passes from the parallel passage 44 or the tandem passage 38 and the parallel passage 44 through the arm second switching valve 22 to the arm joining passage 82d, the joining point 82f, The gas is supplied to the bottom chamber of the arm cylinder 82 through the arm passage 82b. Thereby, pressure oil is supplied from both the first hydraulic pump 12 and the second hydraulic pump 14 to the bottom chamber of the arm cylinder 82, the rod of the arm cylinder 82 can be extended greatly, and the arm 86 performs a large closing operation. It can be carried out.

  Here, in order to supply the pressure oil from the second hydraulic pump 14 to the bottom chamber of the arm cylinder 82 with less energy loss and to close the arm 86, the opening degree of the tandem passage 40 is increased, It is necessary to reduce the pressure oil passing through the parallel passage 42 and increase the pressure oil passing through the tandem passage 40. The parallel passage 42 is provided with a throttle 42A (for securing the pressure oil supplied to the boom cylinder 80 when the boom 84 is started up), and the opening area of the parallel passage 42 is smaller than that of the tandem passage 40. It is.

  Therefore, in the case of an operation that requires a large closing operation of the arm 86 (an operation of extending the rod of the arm cylinder 82), even if the boom 84 is simultaneously started up, It is preferable to reduce the amount of switching from the neutral position to the position D side of the switching valve 18, thereby reducing energy loss when performing the closing operation of the arm 86 (the operation of extending the rod of the arm cylinder 82). it can.

  However, when it is required to supply a large amount of pressure oil to the bottom chamber of the boom cylinder 80, if the amount of switching to the position D side of the second boom switching valve 18 is small, the bottom of the boom cylinder 80 There is a risk of insufficient pressure oil supply to the chamber. Accordingly, in the operation of the hydraulic excavator 70 that simultaneously performs the closing operation of the arm 86 and the raising operation of the boom 84, when the switching amount from the neutral position of the second boom switching valve 18 to the position D side is reduced, It is necessary to determine whether or not the working state of the excavator 70 is a working state in which it is not required to supply a large amount of pressure oil to the bottom chamber of the boom cylinder 80. In the operation of the hydraulic excavator 70 that simultaneously performs the closing operation of the arm 86 and the raising operation of the boom 84, it is necessary to perform a large closing operation of the arm 86. However, a large amount of pressure oil may be supplied to the bottom chamber of the boom cylinder 80. The work state that is not required is, for example, the beginning of excavation work.

  In the early stage of excavation work, the boom 84 is also raised, but the main purpose is to excavate earth and sand by closing the arm 86. For this reason, it is necessary to greatly extend the rod of the arm cylinder 82, and it is necessary to supply a large amount of pressure oil to the bottom chamber of the arm cylinder 82.

  On the other hand, in the early stage of excavation work, a pulling load is applied to the rod of the boom cylinder 80 due to the reaction force during earth and sand excavation due to the closing operation of the arm 86. For this reason, the boom raising operation in the early stage of excavation work is an operation for controlling the extension amount of the rod of the boom cylinder 80 with respect to the force pulling the rod of the boom cylinder 80 (excavation reaction force by the arm operation). This is based on the meter-out control of the pressure oil returning from the rod chamber to the tank T, and it is not required to supply a large amount of pressure oil to the bottom chamber of the boom cylinder 80.

  Therefore, in this embodiment, when it is determined that the working state of the excavator 70 is “beginning of excavation work”, it is determined as “specific working state” in the present invention, and the operation lever 24A is operated. Control is performed so that the switching amount from the neutral position to the position D side of the second boom switching valve 18 with respect to the operation amount in the boom raising direction is smaller than that in other working states. Thereby, in this embodiment, when performing the raising operation | movement of the boom 84 and the closing operation of the arm 86 simultaneously, the energy loss at the time of performing the closing operation of the arm 86 (operation | movement which expands the rod of the arm cylinder 82) is reduced. .

  In the present embodiment, in order to determine whether or not the working state of the excavator 70 is an early stage of excavation work (whether it is a specific working state), the pressure sensors 28 and 30 are provided, and the pressure sensor 28 performs measurement. The pilot pressure data of the pilot passage 24 a and the pilot pressure data of the pilot passage 26 b measured by the pressure sensor 30 are sent to the controller 32.

  Based on the pressure data sent, the controller 32 determines whether or not the working state of the excavator 70 corresponds to the early stage of excavation work, and based on the determination result, an electric signal line is connected to the solenoid portion 34a of the electromagnetic proportional valve 34. An electrical signal is sent through 32a. This electric signal includes a command for adjusting the opening degree of the pilot passage 36a to be small when it is determined that the working state of the hydraulic excavator 70 is an early stage of excavation work. As a result, when the excavator 70 is in the early stage of excavation work, the pilot pressure input to the pilot port 18a of the second boom switching valve 18 is reduced, and the boom with respect to the operation amount of the operation lever 24A in the boom raising direction is reduced. The amount of switching from the neutral position to the position D side of the second switching valve 18 is reduced, and a wide opening area of the tandem passage 40 is ensured. As a result, in the early stage of excavation work in which the excavator 70 performs the closing operation of the arm 86 and the raising operation of the boom 84 at the same time, the energy loss is reduced and the pressure oil from the second hydraulic pump 14 is sent to the bottom of the arm cylinder 82. The arm 86 can be supplied to the chamber, and the closing operation of the arm 86 can be performed with little energy loss without hindering the raising operation of the boom 84.

  Therefore, when the controller 32 determines that the working state of the excavator 70 corresponds to the early stage of excavation work, in this embodiment, the movable range of the spool of the second switching valve 18 for the boom is narrowly limited. Become. This situation is schematically shown in a graph in FIG. FIG. 2 is a graph showing an example of the relationship between the switching amount from the neutral position to the position D side of the second boom switching valve 18 and the opening area of the tandem passage 40. For reference, the relationship with the opening area of the boom confluence passage (meter-in passage) 80c is also shown in FIG.

  In this embodiment, when it is determined that the working state of the excavator 70 corresponds to the early stage of excavation work, the controller 32 moves to the position D of the spool of the second switching valve 18 for boom as shown in FIG. The opening range of the tandem passage 40 is ensured to be wide by controlling so that the movable range is narrow.

  When the operation lever 24A of the boom remote control lever device 24 is tilted to the right in FIG. 1 and the pilot pressure is supplied to the pilot passage 24a, the first boom switching valve 16 is switched to the position A. Therefore, the return oil from the rod chamber of the boom cylinder 80 is discharged to the tank T through the boom passage 80b and the first boom switching valve 16, and is thus discharged to the tank T through the first boom switching valve 16. Meter-out control can be performed on the returning pressure oil.

  Next, in the present embodiment, how the controller 32 determines whether or not the work state of the excavator 70 corresponds to the early stage of excavation work (specific work state) will be specifically described.

  In the early stage of excavation work, the main purpose is to excavate earth and sand by the closing operation of the arm 86, and therefore it is necessary to increase the extension speed and extension thrust of the rod of the arm cylinder 82. On the other hand, as described above, the boom raising operation in the early stage of excavation work is an operation for controlling the extension amount of the rod of the boom cylinder 80 with respect to the force pulling the rod of the boom cylinder 80 (excavation reaction force due to the arm operation). The amount of pressure oil supplied to the bottom chamber of the boom cylinder 80 does not need to be increased so much, based on meter-out control of the pressure oil returning from the rod chamber of the boom cylinder 80 to the tank T.

  Therefore, the amount of pressure oil supplied to the bottom chamber of the arm cylinder 82 exceeds a predetermined threshold required in the early stage of excavation work, and the amount of pressure oil supplied to the bottom chamber of the boom cylinder 80 is less than that of the excavation work. If it falls below a predetermined threshold required in the early stage, the working state of the excavator 70 can be determined as the early stage of excavation work or a working state equivalent thereto.

  In the present embodiment, pilot pressure data supplied to the pilot port 20b of the first arm switching valve 20 and the pilot port 22b of the second arm switching valve 22 is measured by the pressure sensor 30, and the pilot pressure data is an electrical signal. It is sent to the controller 32 via the line 30a. Based on the pilot pressure data, the controller 32 determines the switching amount from the neutral position of the arm first switching valve 20 to the position I side and the switching amount from the neutral position of the arm second switching valve 22 to the position L side. The amount of pressure oil supplied to the bottom chamber of the arm cylinder 82 can be determined, and the state of the closing operation of the arm 86 can be determined.

  In the present embodiment, the pilot pressure data supplied to the pilot port 16 a of the first boom switching valve 16 is measured by the pressure sensor 28, and the pilot pressure data is sent to the controller 32. Based on the pilot pressure data, the controller 32 can determine the amount of switching from the neutral position of the first boom switching valve 16 to the position A side, and the amount of pressure oil supplied to the bottom chamber of the boom cylinder 80 can be determined. It is possible to determine the situation of the rising operation of the boom 84.

  Therefore, in the present embodiment, the controller 32 determines whether the working state of the excavator 70 is an early stage of excavation work based on the pilot pressure data measured by the pressure sensor 30 and the pilot pressure data measured by the pressure sensor 28. It can be judged.

  In the present embodiment, the pilot pressure data measured by the pressure sensor 30 and the pilot pressure data measured by the pressure sensor 28 are used as parameters to determine whether or not the working state of the excavator 70 is an early stage of excavation work. As a result, it is determined whether or not it is in a specific work state, but a parameter (arm closing parameter) that can determine the state of the arm 86 closing operation and the state of the boom 84 rising operation are determined. As long as it is a parameter that can be used (boom raising parameter), another index may be used as a parameter. For example, the operating amount of the arm operating lever 26A (the operating amount in the left direction in FIG. 1) is used as an arm closing parameter, and the operating amount of the boom operating lever 24A (the operating amount in the right direction in FIG. 1) is used as a boom raising parameter. It is good. Further, for example, a boom pressure oil amount detecting means for detecting the pressure oil amount supplied to the bottom chamber of the boom cylinder 80 is provided in the boom passage 80a, and the pressure oil amount supplied to the bottom chamber of the arm cylinder 82 is detected. Arm pressure oil amount detecting means is provided in the arm passage 82b, the pressure oil amount supplied to the bottom chamber of the arm cylinder 82 is used as an arm closing parameter, and the pressure oil amount supplied to the bottom chamber of the boom cylinder 80 is The boom raising parameter may be used.

  Further, in the early stage of excavation work, since the arm closing operation is performed largely, it is necessary to increase the extension speed and extension thrust of the rod of the arm cylinder 82, and the extension speed and extension thrust of the rod of the arm cylinder 82 are increased by the hydraulic excavator. It is effective to take this into account when determining whether the work state 70 is an early stage of excavation work. Therefore, a means for detecting the extension speed and extension thrust of the rod of the arm cylinder 82 is provided, and whether or not the working state of the hydraulic excavator 70 is an early stage of excavation work in consideration of the extension speed and extension thrust of the rod of the arm cylinder 82 May be judged.

  In order to increase the extension speed and extension thrust of the rod of the arm cylinder 82, it is necessary to increase the discharge pressures of the first hydraulic pump 12 and the second hydraulic pump 14. Therefore, a means for detecting the discharge pressures of the first hydraulic pump 12 and the second hydraulic pump 14 is provided, and the working state of the excavator 70 is determined by excavating work in consideration of the discharge pressures of the first hydraulic pump 12 and the second hydraulic pump 14. It may be judged whether it is the beginning of the.

  However, the application of the present invention is not particularly limited to the “early stage of excavation work”, and the controller directly determines whether the work state of the construction machine is a specific work state based on various parameters. It doesn't matter at all.

  Next, a hydraulic circuit 50 for a hydraulic excavator according to a second embodiment of the present invention will be described.

  FIG. 3 is a diagram showing a configuration of a hydraulic circuit 50 of a hydraulic excavator according to the second embodiment of the present invention. The same components as those of the hydraulic circuit 10 according to the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the hydraulic circuit 10 according to the first embodiment, the opening degree of the pilot passage 36a is adjusted by the electromagnetic proportional valve 34 based on the measurement data of the pressure sensors 28 and 30, and the pilot pressure from the pilot hydraulic pump 36 is adjusted, thereby The pilot pressure is input from the passage 36a to the pilot port 18a of the second boom switching valve 18, but in the hydraulic circuit 50 according to the second embodiment, the branch point 24b on the pilot passage 24a and the second boom switching are provided. A pilot passage 24c connecting the pilot port 18a of the valve 18 is provided so that the pilot pressure input to the pilot port 16a of the first boom switching valve 16 is input to the pilot port 18a of the second boom switching valve 18. did. Further, an electromagnetic proportional valve 54 is provided in the middle of the pilot passage 24c, and the opening of the pilot passage 24c is adjusted by the electromagnetic proportional valve 54, whereby the pilot port 16a of the first boom switching valve 16 is input. The pilot pressure is reduced from the pilot pressure, and the pilot pressure is input to the pilot port 18a of the second boom switching valve 18.

  Similarly to the controller 32 of the first embodiment, the controller 52 of the hydraulic circuit 50 according to the second embodiment is based on the measurement data of the pressure sensors 28 and 30, and the working state of the hydraulic excavator 70 is the first stage of excavation work (specific Is determined to be in a working state), and an electric signal is sent to the solenoid portion 54a of the electromagnetic proportional valve 54 via the electric signal line 52a based on the determination result. This electric signal includes a command for adjusting the opening degree of the pilot passage 24c to be small when it is determined that the working state of the hydraulic excavator 70 is an early stage of excavation work. The electromagnetic proportional valve 54 switches the spool according to the transmitted electrical signal, and adjusts the opening of the pilot passage 24c to be small when it is determined that the excavation work is in the early stage. Thus, the pilot pressure supplied to the pilot port 18a of the second boom switching valve 18 is adjusted to be lower than the pilot pressure input to the pilot port 16a of the first boom switching valve 16, and the boom first The amount of switching from the neutral position to the position D side is limited. Thus, in the early stage of excavation work in which the excavator 70 performs the closing operation of the arm 86 and the raising operation of the boom 84 at the same time, the energy loss is reduced and the pressure oil from the second hydraulic pump 14 is sent to the bottom of the arm cylinder 82 The arm 86 can be supplied to the room, and the closing operation of the arm 86 can be performed with less energy loss without hindering the boom raising operation.

  Next, a hydraulic circuit 60 for a hydraulic excavator according to a third embodiment of the present invention will be described.

  FIG. 4 is a diagram showing a configuration of a hydraulic circuit 60 of a hydraulic excavator according to the third embodiment of the present invention. The same components as those of the hydraulic circuit 50 according to the second embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the hydraulic circuit 10 according to the first embodiment, pilot pressure is supplied to the pilot port 18a and no pilot pressure is supplied to the pilot port 18b connected to the tank T in the second switching valve 18 for boom. In the hydraulic circuit 60 according to the third embodiment, the pilot pressure is supplied from the pilot hydraulic pump 66 to the pilot port 18b of the second boom switching valve 18 via the pilot passage 66a. Further, the pilot port 18a of the boom second switching valve 18 is input to the pilot port 16a of the boom first switching valve 16 through the pilot passage 24c, similarly to the hydraulic circuit 50 according to the second embodiment. The pilot pressure was input. However, the pilot passage 24c is not provided with an electromagnetic proportional valve, and the pilot port 18a of the second boom switching valve 18 has the same magnitude as the pilot pressure input to the pilot port 16a of the first boom switching valve 16. The pilot pressure is input. In addition, an electromagnetic proportional valve 64 is provided in the middle of the pilot passage 66a. By adjusting the opening of the pilot passage 66a with the electromagnetic proportional valve 64, an input is made to the pilot port 18b of the second switching valve 18 for boom. The pilot pressure to be adjusted was adjusted.

  In the hydraulic circuit 60 according to the third embodiment, since the pilot pressure is input to the pilot ports 18a and 18b at both ends of the second switching valve 18, the spool of the boom second switching valve 18 is caused by the difference between the pilot pressures. Will move.

  Similarly to the controller 32 of the first embodiment, the controller 62 of the hydraulic circuit 60 according to the third embodiment is based on the measurement data of the pressure sensors 28 and 30, and the working state of the hydraulic excavator 70 is the first stage of excavation work (specific It is determined whether or not it is in a working state), and based on the determination result, an electric signal is sent to the solenoid portion 64a of the electromagnetic proportional valve 64 via the electric signal line 62a. This electric signal includes a command for adjusting the opening degree of the pilot passage 66a to be small when it is determined that the working state of the hydraulic excavator 70 is an early stage of excavation work. The electromagnetic proportional valve 64 switches the spool in accordance with the sent electric signal, and adjusts the pilot passage 66a to have a small opening when it is determined that the excavation work is in the early stage. As a result, the pilot pressure supplied to the pilot port 18b of the second boom switching valve 18 is reduced and adjusted, and the switching amount from the neutral position to the position D side of the second boom switching valve 18 is limited. Thus, in the early stage of excavation work in which the excavator 70 performs the closing operation of the arm 86 and the raising operation of the boom 84 at the same time, the energy loss is reduced and the pressure oil from the second hydraulic pump 14 is sent to the bottom of the arm cylinder 82 The arm 86 can be supplied and the arm 86 can be closed with little energy loss.

  The specific working state in which the present invention is effective includes not only the early stage of excavation work, but also, for example, floor excavation work in which the closing operation of the arm and the raising operation of the boom are performed simultaneously to horizontally pull the bucket toward the front. is there. The floor excavation work can be determined by a method (satisfaction of conditions) substantially the same as the early stage of the excavation work.

  In addition, when the driver manually provides a switch or the like that can specify that these work states (the early stage of excavation work, floor digging work, etc.), the present invention can be achieved by simply checking whether or not the switch is turned on. It is possible to determine whether or not this is a specific work state. Therefore, as long as it is confirmed that the arm closing operation and the boom raising operation are performed simultaneously, the operation of the sensor or the like for detecting the actual value of the parameter is stopped. However, it is possible to control the switching amount from the neutral position of the second boom switching valve with respect to the operation amount of the boom operating lever to be smaller than in a case other than a specific working state.

  Further, in the embodiment described above, the arm second switching valve 22 is provided on the downstream side of the boom first switching valve 16 in the tandem passage 38, but the arm second switching valve 22 is switched to the boom first switching valve. It may be provided on the upstream side of the valve 16.

  Further, the present invention can be applied without depending on a pump control system such as a positive control, a negative control, and an open center.

  For example, it can be suitably used for a hydraulic excavator that frequently performs simultaneous operation (combined operation) for simultaneously operating a boom and an arm.

DESCRIPTION OF SYMBOLS 10, 50, 60 ... Hydraulic circuit 12 ... 1st hydraulic pump 14 ... 2nd hydraulic pump 16 ... 1st switching valve for booms 18 ... 2nd switching valve for booms 20 ... 1st switching valve for arms 22 ... 2nd for arms Switch valve 24 ... Boom remote control lever device 26 ... Arm remote control lever device 24A ... Boom operation lever 26A ... Arm operation lever 28 ... Pressure sensor (pilot pilot pressure detection means)
30 ... Pressure sensor (pilot pressure detecting means for arm)
32, 52, 62 ... Controller 34, 54, 64 ... Electromagnetic proportional valve 36, 66 ... Pilot hydraulic pump 38, 40 ... Tandem passage 42, 44 ... Parallel passage 70 ... Hydraulic excavator 80 ... Boom cylinder 82 ... Arm cylinder 84 ... Boom 86 ... arm 88 ... bucket

Claims (9)

A first boom switching valve for switching the direction and flow rate of the pressure oil connected to the first hydraulic pump and supplied to the boom cylinder that drives the boom;
A second switching valve for a boom, connected to a second hydraulic pump, for switching the direction and flow rate of pressure oil supplied to the boom cylinder;
A first switching valve for an arm that is tandemly connected to the second hydraulic pump downstream of the second switching valve for the boom, and that switches the direction and flow rate of pressure oil supplied to an arm cylinder that drives the arm; ,
A second switching valve for an arm that is connected in tandem with the first switching valve for the boom to the first hydraulic pump, and that switches the direction and flow rate of the pressure oil supplied to the arm cylinder;
A boom operation lever for operating the first boom switching valve and the second boom switching valve;
In the hydraulic circuit of construction machinery with
A second boom switching valve control mechanism capable of changing the degree of switching from the neutral position of the second boom switching valve to the amount of operation of the boom operating lever;
The boom second switching valve with respect to the operation amount of the boom operation lever in a specific work state in which the closing operation of the arm and the raising operation of the boom are performed at the same time and satisfying a predetermined condition A hydraulic circuit for a construction machine, wherein a switching amount from a neutral position is controlled to be smaller than that in a state other than the specific working state. In claim 1,
Whether at least one of the specific working states is determined by comparing at least one of the arm closing parameters indicating the degree of the closing operation of the arm with a predetermined threshold, and at least a boom raising parameter indicating the degree of the boom raising operation A hydraulic circuit for a construction machine, wherein one is determined by comparing one with a predetermined threshold value. In claim 2, further:
At least one of a pilot pressure detecting means for detecting a pilot pressure for switching the first switching valve for the boom, a pilot pressure for switching the first switching valve for the arm, and a pilot pressure for switching the second switching valve for the arm. An arm pilot pressure detecting means for detecting
One of the arm closing parameters is a pilot pressure for switching the first switching valve for the arm or a pilot pressure for switching the second switching valve for the arm, and one of the boom raising parameters is a pilot for switching the first switching valve for the boom. A hydraulic circuit of a construction machine characterized by being a pressure. In claim 2 or 3, further
An arm operating lever for operating the first arm switching valve and the second arm switching valve;
A hydraulic circuit for a construction machine, wherein one of the arm closing parameters is an operation amount of the arm operation lever, and one of the boom raising parameters is an operation amount of the boom operation lever. In any one of Claims 2-4, Furthermore,
Boom pressure oil amount detection means for detecting the pressure oil amount supplied to the bottom chamber of the boom cylinder; and arm pressure oil amount detection means for detecting the pressure oil amount supplied to the bottom chamber of the arm cylinder; With
One of the arm closing parameters is the amount of pressure oil supplied to the bottom chamber of the arm cylinder, and one of the boom raising parameters is the amount of pressure oil supplied to the bottom chamber of the boom cylinder. Hydraulic circuit for construction machinery. In any one of Claims 1-5, Furthermore,
Arm cylinder rod extension thrust detection means for detecting the thrust at the time of rod extension of the arm cylinder,
A hydraulic circuit for a construction machine that determines whether or not the specific working state is present based on a thrust force when the rod of the arm cylinder is extended. In any one of Claims 1-6, Furthermore,
A discharge pressure detecting means for detecting a discharge pressure of the first hydraulic pump and the second hydraulic pump;
A hydraulic circuit for a construction machine, wherein whether or not the specific working state is present is determined based on discharge pressures of the first hydraulic pump and the second hydraulic pump. In any one of Claims 1-7,
Provided with excavation work judgment means for judging whether or not the working state of the construction machine is an early stage of excavation work;
A hydraulic circuit for a construction machine that determines whether or not the work state is the specific work state based on whether or not the work state of the construction machine is an early stage of excavation work. In any one of Claims 1-8, Furthermore,
A floor digging work judging means for judging whether or not the working state of the construction machine is a floor digging work;
A hydraulic circuit for a construction machine that determines whether or not the work state is the specific work state based on whether or not the work state of the construction machine is a floor digging work.

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