JP2010236607A - Hydraulic control circuit in construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic control circuit of a construction machine equipped with working attachments which can avoid the deceleration of working speed when a hydraulic actuator for attachment and the other hydraulic actuator work together while preventing an excessive flow amount from flowing into the hydraulic actuator for attachment. <P>SOLUTION: First and second pumps 11, 12 are controlled in discharge flow independently by the use of an electromagnetically proportional pressure reducing valve 35 for first pump control which outputs signal pressure to a capacity variable means 11a of the first pump 11 based on operations of control valves 20-24 supplied with hydraulic oil from the first pump 11 when a hydraulic actuator 18 for attachment is driven, and an electromagnetically proportional pressure reducing valve 36 for second pump control which outputs the signal pressure to a capacity variable means 12a of the second pump 12 based on operations of control valves 25-29 supplied with hydraulic oil from the second pump 12 when the actuator is driven. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technical field of a hydraulic control circuit in a construction machine such as a hydraulic excavator to which various work attachments are attached.

In general, some construction machines, such as hydraulic excavators, are configured so that various work attachments driven by a hydraulic actuator, such as a grapple, a hydraulic breaker, or a lifting magnet, can be exchangeably mounted. In order to prevent an excessive flow rate from flowing through the hydraulic actuator that drives the work attachment and damage to the hydraulic actuator that drives the work attachment, a specific flow rate that conforms to each work attachment hydraulic actuator is determined. In addition, conventionally, a technology that can control the discharge flow rate of a pump, which is a hydraulic pressure supply source of a hydraulic actuator for work attachment, by an electromagnetic proportional valve that operates according to a signal from a controller, so that it can be limited according to the specified flow rate. Is known (for example, see Patent Document 1).
Incidentally, in construction machines such as hydraulic excavators, in addition to the hydraulic actuator for work attachment, for example, a traveling motor, a swing motor, or many other hydraulic actuators such as a boom cylinder, a stick cylinder, and a bucket cylinder are provided. In some cases, two pumps are provided as a hydraulic pressure supply source of these hydraulic actuators. In the one disclosed in Patent Document 1, pressure oil is supplied from two pumps to a plurality of hydraulic actuators including a hydraulic actuator for work attachment. It is configured.

JP 2008-32175 A

  However, in the thing of the said patent document 1, when restrict | limiting the discharge flow rate of a pump according to the hydraulic actuator for work attachments, it is the structure which controls the discharge flow rate of two pumps simultaneously with one electromagnetic proportional valve. For this reason, when the hydraulic actuator for work attachment and other hydraulic actuators are driven in conjunction with each other, even if it is necessary to limit the discharge flow rate of only one of the two pumps, the other pump that does not need to be restricted However, there is a problem that the operating speed of the hydraulic actuator supplied with pressure oil from the other pump is lowered and the working efficiency is inferior, and the problem to be solved by the present invention is here. is there.

  The present invention was created with the object of solving these problems in view of the above circumstances, and the invention of claim 1 is equipped with a work attachment driven by a hydraulic actuator for attachment. In the construction machine, the hydraulic control circuit of the construction machine includes the attachment hydraulic actuator, other hydraulic actuators other than the attachment hydraulic actuator, and variable displacement first and second pumps serving as hydraulic supply sources, A first group consisting of a control valve for the first attachment that controls the oil supply from the first pump to the hydraulic actuator for attachment, and another control valve that controls the oil supply from the first pump to any of the other hydraulic actuators Attach from control valve and second pump A second group of control valves comprising a control valve for second attachment for controlling oil supply to the hydraulic actuator for the actuator, and another control valve for controlling oil supply from the second pump to any other hydraulic actuator; The control valve operation detecting means for detecting the operation of each control valve of the first and second groups and the discharge flow rate of the first pump based on the operation of the control valve of the first group when driving the attachment hydraulic actuator. The first pump control means for controlling, and the second pump control means for controlling the discharge flow rate of the second pump based on the operation of the control valve of the second group, the first and second pump control means, The first and second pump discharge flow rates When the control valve for single action is controlled, the flow rate for attachment is set in advance according to the hydraulic actuator for attachment, while the control valve for the first and second attachments and the other of the first and second groups are controlled. The hydraulic control circuit in a construction machine is characterized by controlling each of the attachment flow rate to a flow rate obtained by adding a flow rate set according to another hydraulic actuator to the attachment flow rate.

  According to the first aspect of the invention, when the attachment hydraulic actuator is driven, the discharge flow rates of the first and second pumps are independently controlled by the first and second pump control means. Then, when the first and second attachment control valves are single acting, by controlling the discharge flow rate of the first and second pumps to be the attachment flow rate, an excessive flow rate will flow to the attachment hydraulic actuator. The first and second attachment control valves are connected to the other control valves of the first and second groups while pressure oil is supplied to the other control valves that are interlocked. The discharge flow rate of the pump, the second pump, or both the first and second pumps can be transferred to other hydraulic actuators. Therefore, it can be increased by the set flow rate, so that it can be avoided that the pump flow rate is insufficient at the time of interlocking and the operating speed of the hydraulic actuator is reduced, which contributes to the improvement of work efficiency and is necessary. It is possible to eliminate the waste of increasing the pump flow rate.

It is a side view of a hydraulic excavator equipped with a crusher as a work attachment. It is a hydraulic circuit diagram of a hydraulic excavator. It is a block diagram which shows the input / output of a controller. It is a control block diagram of a pump flow rate calculation unit.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a hydraulic excavator (which is an example of a construction machine according to the present invention), and the hydraulic excavator 1 is a crawler-type lower traveling body 2 and an upper portion that is rotatably supported by the lower traveling body 2. The revolving structure 3 includes a front working machine 4 attached to the upper revolving structure 3, and the front working machine 4 further includes a boom whose base end is supported by the upper revolving structure 3 so as to be swingable up and down. 5. The stick 6 is supported by the tip of the boom 5 so as to be swingable back and forth, and the work attachment 7 is attached to the tip of the stick 6. Here, in the present embodiment, the crusher is illustrated in FIG. 1 as an example of the work attachment 7, but not only the crusher but also a bucket that is normally equipped on the hydraulic excavator 1, a grapple, Various work attachments (not shown) such as a hydraulic breaker or a lifting magnet can be mounted in a replaceable manner. In FIG. 1, 8 is a boom cylinder that swings the boom 5, 9 is a stick cylinder that swings the stick 6, and 10 is a bucket cylinder that swings the work attachment 7. The bucket cylinder 10 is referred to as the bucket cylinder 10 because it is a cylinder that swings the bucket when the bucket is mounted as the work attachment 7, but when the work attachment 7 other than the bucket is mounted. The bucket cylinder 10 operates as a hydraulic cylinder for swinging the work attachment 7 with respect to the stick 6.

  Next, FIG. 2 shows a hydraulic circuit diagram of the excavator 1. In FIG. 2, reference numerals 11 and 12 denote variable displacement first and second pumps driven by the engine E, and 11a and 12a denote first and second The capacity variable means of the two pumps 11 and 12, 13 is a pilot pump as a pilot pressure supply source, and 14 is an oil tank. 8-10, 15-18 are hydraulic actuators using the first and second pumps 11, 12 as hydraulic supply sources, 8, 9, 10 are the boom cylinder, stick cylinder, bucket cylinder, A right traveling motor, 16 is a left traveling motor, 17 is a turning motor, and 18 is an attachment hydraulic actuator that drives the work attachment 7. In the present embodiment, an open / close cylinder that opens and closes the crushing arm 19 provided in the crusher is provided as the attachment hydraulic actuator 18 (see FIG. 1). The boom cylinder 8, the stick cylinder 9, the bucket cylinder 10, the right traveling motor 15, the left traveling motor 16, and the turning motor 17 correspond to other hydraulic actuators of the present invention.

  Further, 20 to 29 are control valves for controlling oil supply to the respective hydraulic actuators based on the operation of a hydraulic actuator operating tool (not shown). The control valves 20 to 24 for the first attachment, the bucket, the first boom, and the first stick are connected to the discharge line of the first pump 11 and supplied with pressure oil from the first pump 11. The control valves 25 to 29 for left side running, turning, second stick, second boom, and second attachment are connected to the discharge line of the second pump 12 and are pressurized oil from the second pump 12. Although it is configured to be supplied, hereinafter, control valves 20 to 24 supplied with pressure oil from the first pump 11 are used. A first group A, the control valve 25 to 29 are pressurized oil supplied from the second pump 12 and the second group B. Further, among the control valves 20 to 24 of the first group A, the control valves 20 and 22 to 24 other than the control valve 21 for the first attachment are referred to as other control valves 20 and 22 to 24 of the first group A, Further, among the control valves 25 to 29 of the second group B, the control valves 25 to 28 other than the control valve 29 for the second attachment are referred to as other control valves 25 to 28 of the second group B.

  Each of the control valves 20 to 29 is located at a neutral position N where the oil supply control for the hydraulic actuator is not performed when the corresponding hydraulic actuator operation tool is not operated. Is switched to the operating position X or Y for performing oil supply control on the corresponding hydraulic actuator by the pilot pressure output based on the above. In this case, the pilot pressure output according to the increase / decrease of the operation amount of the hydraulic actuator operating tool increases / decreases, and the control valves 20-29 correspond to the increase / decrease of the pilot pressures input to the control valves 20-29. The movement stroke of the spool is increased or decreased, whereby the supply flow rate to the hydraulic actuator is controlled to increase or decrease.

  Here, the boom cylinder 8 is supplied with pressure oil from the first pump 11 when the boom 5 is lowered, but is supplied with pressure oil from both the first and second pumps 11 and 12 when the boom 5 is raised. Therefore, a first boom control valve 24 supplied with pressure oil from the first pump 11 and a second boom control valve 28 supplied with pressure oil from the second pump 12 are provided. . The stick cylinder 9 includes a first stick control valve 24 supplied with pressure oil from the first pump 11 and a second pump so that pressure oil can be supplied from both the first and second pumps 11 and 12. 12 is provided with a control valve 27 for the second stick supplied with pressure oil from 12. Further, the attachment actuator 18 is for the first attachment that is supplied with pressure oil from the first pump 11 so that the pressure oil can be supplied from either the first or second pump, or both pumps 11 and 12. Although the control valve 21 and the control valve 29 for the second attachment supplied with pressure oil from the second pump 12 are provided, in this embodiment, the work attachment 7 requires crushing that requires a flow rate of two pumps. Since the machine is mounted, pressure oil is supplied from both the first and second pumps 11 and 12.

  Further, the control valves 20 to 24 of the first group A have center bypass valve passages 20c to 24c for flowing the pressure oil supplied from the first pump 11 to the oil tank 14 via the first throttle 31. The center bypass valve passage that is formed and that allows the control oil 25 to 29 of the second group B to flow the pressure oil supplied from the second pump 12 to the oil tank 14 via the second throttle 32. 25c to 29c are formed. The flow rates through these center bypass valve passages 20c to 29c are the largest when the control valves 20 to 29 are in the neutral position N, and the smaller the spool movement stroke, the smaller the operation amount of the hydraulic actuator operation tool. Control is performed so that the passage flow rate of the center bypass valve passages 20c to 29c decreases as the number increases. The upstream pressures of the first and second throttles 31 and 32 are the first and second center bypass signal pressures Ps1 and Ps2, and are input ports of first and second shuttle valves 33 and 34, which will be described later. 33a and 34a are input respectively.

  The first and second shuttle valves 33 and 34 are supplied with first and second center bypass signal pressures Ps1 and Ps2 input from one input port 33a and 34a, and first and second pump control electromagnetic proportionalities described later. A high pressure side is selected from the first and second attachment mode signal pressures Pa1 and Pa2 input from the pressure reducing valves 35 and 36 to the other input ports 33b and 34b, and the selected signal pressure is supplied to the first and second pumps. 11 and 12 to the variable capacity means 11a and 12a, respectively. When the signal pressure input from the first and second shuttle valves 33 and 34 is high, the capacity variable means 11a and 12a reduce the discharge flow rate of the first and second pumps 11 and 12 and the signal pressure is low. The so-called negative flow rate control is performed to increase the discharge flow rate. In the present embodiment, the first and second shuttles 33 and 34 and the first and second pump control electromagnetic proportional pressure reducing valves 35 and 36 are assembled together as one valve unit.

  The first and second pump control electromagnetic proportional pressure reducing valves 35 and 36 set the first and second attachment mode signal pressures Pa1 and Pa2 to the first and second based on a control signal output from a controller 37 described later. It outputs to the other input ports 33b and 34b of the two shuttle valves 33 and 34, respectively. The first pump control means of the present invention includes the first pump control electromagnetic proportional pressure reducing valve 35 and the controller 37, and the second pump control means of the present invention includes the second pump control electromagnetic proportional pressure control valve. A pressure reducing valve 36 and a controller 37 are included.

  On the other hand, as shown in the block diagram of FIG. 3, the controller 37 has, on the input side, the right side traveling, the first attachment, the bucket, the first boom, the first stick, the left side traveling, the turning, Control valve operation detecting means 20a to 29a for detecting the switching operation of the control valves 20 to 29 for the second stick, the second boom, and the second attachment are connected, respectively, and the first, The second pump control electromagnetic proportional pressure reducing valves 35 and 36 are connected, and a pump flow rate calculation unit 38 to be described later is provided. The control valve operation detecting means 20a to 29a are pressure switches and pressure sensors for detecting input pilot pressures to the control valves 20 to 29, or the control valves 20 to 29 are based on the operation of a hydraulic actuator operating tool. Therefore, it can be configured by using an operation tool operation detection means (for example, an operation lever angle detection sensor) that detects an operation of each hydraulic actuator operation tool.

  Next, the control performed by the controller 37 will be described. First, the controller 37 determines whether or not the first attachment control valve 21 is operating based on the detection signal from the first attachment control valve operation detecting means 21a. Determine. When it is determined that the first attachment control valve 21 is not in operation (positioned at the neutral position N), the controller 37 controls the first pump control electromagnetic proportional pressure reducing valve 35 to A control signal for outputting one attachment mode signal pressure Pa1 is not output. Thereby, the tank pressure is input to the other input port 33b of the first shuttle valve 33, and therefore the first shuttle valve 33 selects the first center bypass signal pressure Ps1 input from the one input port 33a, The first center bypass signal pressure Ps1 is output to the capacity varying means 11a of the first pump 11. Thus, when the first attachment control valve 21 is in the neutral position N, the discharge flow rate of the first pump 11 is controlled by the other control valves 20, 22-24 of the first group A by the first center bypass signal pressure Ps1. The discharge flow rate is controlled so as to increase as the movement stroke increases (the operation amount of the hydraulic actuator operating tool increases).

  On the other hand, when it is determined that the first attachment control valve 21 is operating (positioned at the operation position X or Y), the controller 37 controls the electromagnetic proportional pressure reducing valve 35 for controlling the first pump. A control signal for outputting the first attachment mode signal pressure Pa1 is output so that the pump flow rate of the first pump 11 is the flow rate obtained by the pump flow rate calculation unit 38 to be described later. When the first attachment mode signal pressure Pa1 is higher than the first center bypass signal pressure Ps1 (signal pressure for reducing the pump flow rate), the high-pressure first attachment mode signal pressure Pa1 is the first shuttle valve. 33 is selected and input to the capacity variable means 11 a of the first pump 11. Thereby, when the control valve 21 for the first attachment is located at the operating position X or Y, the discharge flow rate of the first pump 11 is calculated by the pump flow rate calculation unit 38 by the first attachment mode signal pressure Pa1. It is controlled so that the pump flow rate becomes the same. When the first center bypass signal pressure Ps1 is higher than the first attachment mode signal pressure Pa1 (signal pressure for reducing the pump flow rate), the first center bypass signal pressure Ps1 is variable in capacity of the first pump 11. Input to means 11a. Thus, the discharge flow rate of the first pump 11 is limited so as not to exceed the pump flow rate calculated by the pump flow rate calculation unit 38.

  Further, the controller 37 determines whether or not the second attachment control valve 29 is operating based on the detection signal from the second attachment control valve operation detecting means 29a. When it is determined that the second attachment control valve 29 is not operating (positioned at the neutral position N), the controller 37 controls the second pump control electromagnetic proportional pressure reducing valve 36 to The control signal for the two attachment mode signal pressure Pa2 output is not output. Thereby, the tank pressure is input to the other input port 34b of the second shuttle valve 34, and therefore the second shuttle valve 34 selects the second center bypass signal pressure Ps2 input from the one input port 34a, The second center bypass signal pressure Ps2 is output to the capacity varying means 12a of the second pump 12. Thus, when the control valve 29 for the second attachment is in the neutral position N, the discharge flow rate of the second pump 12 is moved by the other control valves 25 to 28 of the second group B by the second center bypass signal pressure Ps2. The discharge flow rate is controlled to increase as the stroke increases (the operation amount of the hydraulic actuator operating tool increases).

  On the other hand, when it is determined that the second attachment control valve 29 is in operation (positioned at the operation position X or Y), the controller 37 controls the second pump control electromagnetic proportional pressure reducing valve 36. In order to set the pump flow rate of the second pump 12 to the flow rate calculated by the pump flow rate calculation unit 38, which will be described later, a control signal for outputting the second attachment mode signal pressure Pa2 is output. When the second attachment mode signal pressure Pa2 is higher than the second center bypass signal pressure Ps2 (signal pressure for reducing the pump flow rate), the high-pressure second attachment mode signal pressure Pa2 is the second shuttle valve. 34 is selected and input to the capacity variable means 12 a of the second pump 12. Thus, when the second attachment control valve 29 is located at the operating position X or Y, the discharge flow rate of the second pump 12 is calculated by the pump flow rate calculation unit 38 by the second attachment mode signal pressure Pa2. It is controlled so that the pump flow rate becomes the same. When the second center bypass signal pressure Ps2 is higher than the second attachment mode signal pressure Pa2 (signal pressure for reducing the pump flow rate), the second center bypass signal pressure Ps2 is variable in capacity of the second pump 12. Input to means 12a. Thus, the discharge flow rate of the second pump 12 is limited so as not to exceed the pump flow rate calculated by the pump flow rate calculation unit 38.

Next, calculation of the pump flow rates of the first and second pumps 11 and 12 in the pump flow rate calculation unit 38 will be described based on the control block diagram shown in FIG.
First, when calculating the pump flow rate of the first pump 11, the pump flow rate calculation unit 38 sets the first attachment flow rate La1 in the first attachment flow rate setting unit 39, and the first attachment flow rate La1 is set to the first attachment flow rate La1. Output to one adder 40. Here, the first attachment flow rate La1 is a flow rate set in advance according to the type and size of the attachment hydraulic actuator 18 as the supply flow rate from the first pump 11 to the attachment hydraulic actuator 18. The first attachment flow rate La1 and the later-described second attachment flow rate La2 correspond to the attachment flow rate of the present invention.

  Further, the pump flow rate calculation unit 38 determines whether or not the other control valves 20 and 22 to 24 of the first group A are operating in the first group control valve operation signal output unit 41. 20a, 22a-24a based on the detection signals, and when all the other control valves 20, 22-24 of the first group A are not operating (positioned in the neutral position N) Outputs “0” to the first selector 42, while outputting “1” to the first selector 42 when any of the other control valves 20, 22 to 24 is operating.

  The first selector 42 outputs an additional flow rate “0” to the first adder 40 when “0” is input from the first group control valve operation signal output unit 41. On the other hand, when “1” is input from the first group control valve operation signal output unit 41, the first interlocking additional flow rate Lc 1 is output to the first adder 40. The additional flow rate Lc1 at the time of first interlocking is an additional flow rate required for the first pump 11 when interlocking between the first attachment control valve 21 and the other control valves 20, 22-24 of the first group A, The first interlock is set according to each control valve 20, 22-24, and the operation is determined by the first group control valve operation signal output unit 41 according to the control valve 20, 22-24. The hourly additional flow rate Lc1 is output.

  The first adder 40 includes a first attachment flow rate La1 input from the first attachment flow setting unit 39 and an additional flow rate “0” input from the first selector 42 or a first interlocking additional flow rate Lc1. And the added flow rate is output as the pump flow rate of the first pump 11.

  Thus, among the control valves 20 to 24 of the first group A, when the first attachment control valve 21 is operating independently (during single action), the first attachment flow rate La1 is the first pump. 11, and a control signal is output from the controller 37 to the pump control electromagnetic proportional pressure reducing valve 35 so as to output the first attachment mode signal pressure Pa1 for obtaining the pump flow rate. On the other hand, when the control valve 21 for the first attachment of the first group A and the other control valves 20, 22 to 24 are operating in an interlocked manner (when interlocking), the first interlocking flow rate La1 is the first interlock. The flow rate (La1 + Lc1) obtained by adding the hourly additional flow rate Lc1 is calculated as the pump flow rate of the first pump 11, and the first pump control is performed from the controller 37 so as to output the first attachment mode signal pressure Pa1 for obtaining the pump flow rate. A control signal is output to the electromagnetic proportional pressure reducing valve 35 for use.

  The calculation of the pump flow rate of the second pump 12 in the pump flow rate calculation unit 38 is the same as the calculation of the pump flow rate of the first pump 11 described above. ˜29, the second attachment flow rate La2 is calculated as the pump flow rate of the second pump 12 when the second attachment control valve 29 is single-acting, while the second attachment control valve 29 and the second group B At the time of interlocking with other control valves 25 to 28, a flow rate (La2 + Lc2) obtained by adding the second interlocking additional flow rate Lc2 to the second attachment flow rate La2 is calculated as the pump flow rate of the second pump 12. . The second attachment flow rate La2 is a flow rate set in advance according to the type and size of the attachment hydraulic actuator 18 as the supply flow rate from the second pump 12 to the attachment hydraulic actuator 18. Further, the additional flow rate Lc2 at the time of second interlocking is an additional flow rate required for the second pump 12 when interlocking with the control valve 29 for second attachment of the second group B and the other control valves 25 to 28, It is individually set according to the control valves 25-28. In FIG. 4, 43 is a second attachment flow rate setting unit, 44 is a second adder, 45 is a second group control valve operation signal output unit, and 46 is a second selector. The flow rate setting unit 39, the first adder 40, the first group control valve operation signal output unit 41, and the first selector 42 are the same.

  That is, when an operation tool for attachment (not shown) is operated, the first and second attachment control valves 21 and 29 are switched to the operating position X or Y, and these first and second attachment control valves 21 are operated. 29, pressure oil is supplied from both the first and second pumps 11 and 12 to the attachment hydraulic actuator 18, and in this case, the discharge flow rate of the first pump 11 is When the first attachment control valve 21 of the first group A supplied with pressure oil from the pump 11 is single-acting, the first attachment flow rate La1 is controlled to be set in advance, while the first attachment control is performed. When the valve 21 and the other control valves 20, 22 to 24 of the first group A are interlocked, the first attack is performed. It is controlled so as to instruments for flow La1 will flow adding a first interlock when adding flow Lc1 (La1 + Lc1). The discharge flow rate of the second pump 12 is set to a preset second attachment flow rate La2 when the second attachment control valve 29 in the second group B supplied with pressure oil from the second pump 12 is single-acting. On the other hand, when the second attachment control valve 29 and the other control valves 25 to 28 of the second group B are interlocked, the second interlocking additional flow rate Lc2 is added to the second attachment flow rate La2. The flow rate is controlled to be the added flow rate (La2 + Lc2). In the present embodiment, the first attachment flow rate La1 and the second attachment flow rate La2 are supplied so that the same amount of pressure oil is supplied from the first and second pumps 11 and 12 to the attachment hydraulic actuator 18. Are set to the same value, but can be set to different values.

  In the present embodiment configured as described, the hydraulic control circuit of the hydraulic excavator 1 includes the first pump 11 via the first shuttle valve 33 based on the control signal from the controller 37 when the actuator 18 for attachment is driven. The first pump control electromagnetic proportional pressure reducing valve 35 that outputs the first attachment mode signal pressure Pa1 to the capacity variable means 11a and the second attachment mode to the capacity variable means 12a of the second pump 12 via the second shuttle valve 34. A second pump control electromagnetic proportional pressure reducing valve 36 for outputting the signal pressure Pa2 is provided. The discharge flow rate of the first pump 11 is that of the first group A supplied with pressure oil from the first pump 11 by the first attachment mode signal pressure Pa1 output from the electromagnetic proportional pressure reducing valve 35 for controlling the first pump. Among the control valves 20 to 24, when the first attachment control valve 21 that performs oil supply control to the attachment hydraulic actuator 18 is single-acting, the control valve 20 is controlled so as to have a preset first attachment flow rate La1. When the first attachment control valve 21 and the other control valves 20, 22 to 24 of the first group A are interlocked, a flow rate (La1 + Lc1) obtained by adding the first interlocking additional flow rate Lc1 to the first attachment flow rate La1. It will be controlled to become. Further, the discharge flow rate of the second pump 12 is that of the second group B supplied with pressure oil from the second pump 12 by the second attachment mode signal pressure Pa2 output from the electromagnetic proportional pressure reducing valve 36 for controlling the second pump. Among the control valves 25 to 29, when the second attachment control valve 29 that performs oil supply control to the attachment hydraulic actuator 18 is single-acting, the control valve 25 is controlled so as to have a preset second attachment flow rate La2. When the second attachment control valve 29 is interlocked with the other control valves 25 to 28 of the second group B, the second attachment additional flow rate Lc2 is added to the second attachment flow rate La2 to obtain a flow rate (La2 + Lc2). It will be controlled as follows.

  As a result, when the attachment hydraulic actuator 18 is driven, the discharge flow rates of the first and second pumps 11 and 12 are output from the first and second pump control electromagnetic proportional pressure reducing valves 35 and 36, respectively. It is controlled independently by the attachment mode signal pressures Pa1 and Pa2. Thus, when the attachment hydraulic actuator 18 is single-acting, the discharge flow rates of the first and second pumps 11 and 12 can be controlled to be the first and second attachment flow rates La1 and La2. When the hydraulic actuator 18 is linked to any one of the other hydraulic actuators (the boom cylinder 8, the stick cylinder 9, the bucket cylinder 10, the right traveling motor 15, the left traveling motor 16, and the turning motor 17), When the control valve for the actuator is the control valve 20 or 22 to 24 of the first group A, the discharge flow rate of the second pump 12 that supplies pressure oil to the second group B is set to the second attachment flow rate La2. Discharge flow rate of the first pump 11 that supplies pressure oil to the first group A while controlling It can be controlled so as to flow rate and add the first interlock when adding flow Lc1 First attachment for flow La1. If the control valves for other hydraulic actuators to be interlocked are the control valves 25 to 28 of the second group B, the discharge flow rate of the first pump 11 that supplies pressure oil to the first group A is set to the flow rate for the first attachment. While controlling to become La1, the discharge flow rate of the second pump 12 that supplies pressure oil to the second group B is controlled to be a flow rate obtained by adding the second interlocking additional flow rate Lc2 to the second attachment flow rate La2. can do. Further, if the control valves for other hydraulic actuators to be interlocked are the control valves of both the first and second groups A and B, the discharge flow rates of both the first and second pumps 11 and 12 are set to Control can be performed so that the first and second interlocking additional flow rates Lc1 and Lc2 are added to the first and second attachment flow rates La1 and La2. Moreover, in this case, the first and second interlocking additional flow rates Lc1 and Lc2 are flow rates that are individually set according to the other control valves 20, 22 to 28. As for the discharge flow rate, an appropriate flow rate is added according to each of the other hydraulic actuators that are linked.

  Thus, when the attachment hydraulic actuator 18 is single-acting, the discharge flow rate of the first and second pumps 11 and 12 is controlled so as to become the first and second attachment flow rates. While preventing the excessive flow from flowing, when the attachment hydraulic actuator 18 is linked to another hydraulic actuator, the first pump 11 or the second pump 11 that supplies pressure oil to the other hydraulic actuator that is linked. The discharge flow rate of the pump 12 or both the first and second pumps 11 and 12 can be increased by the flow rate set corresponding to the other hydraulic actuators, so that the pump flow rate is insufficient at the time of interlocking. As a result, the operating speed of the hydraulic actuator can be prevented from decreasing, contributing to improved work efficiency. Is possible, it is possible to eliminate waste that would increase the pump flow rate more than necessary.

Needless to say, the present invention is not limited to the above embodiment, and the attachment hydraulic actuator 18 in the above embodiment requires a flow rate of two pumps, so both the first and second pumps are used. 11 and 12 are configured to be supplied with pressure oil, but even an attachment hydraulic actuator that requires only a flow rate for one pump is linked to a pump that serves as a hydraulic supply source of the attachment hydraulic actuator. When configured to be able to switch to the first pump or the second pump according to other hydraulic actuators, etc., by implementing the present invention, the discharge flow rate of the first pump or the second pump serving as the hydraulic supply source is At the time of the single action of the hydraulic actuator for attachment or with the hydraulic actuator for attachment and other hydraulic actuators It can be controlled to a flow rate suitable for the time of integration.
Furthermore, the value of the flow rate for attachment and the additional flow rate added at the time of interlocking with other hydraulic actuators (additional flow rate at the time of the first and second interlocking) are increased or decreased by the control valve spool movement stroke or the operating tool operation amount. It can also be set to increase / decrease corresponding to the increase / decrease, and in this way, the discharge flow rate control of the first and second pumps can be further performed without waste.

  INDUSTRIAL APPLICABILITY The present invention can be used to control the discharge flow rate of a pump that serves as a hydraulic pressure supply source for an attachment hydraulic actuator and other hydraulic actuators in a construction machine such as a hydraulic excavator to which various work attachments are attached.

7 Work attachments 8, 9, 10, 15, 16, 17 Other hydraulic actuators (boom cylinder, stick cylinder, bucket cylinder, right side travel motor, left side travel motor, turning motor)
DESCRIPTION OF SYMBOLS 11 1st pump 12 2nd pump 18 Attachment hydraulic actuator 20, 22-24 Other control valve of 1st group 21 Control valve for 1st attachment 25-28 Other control valve of 2nd group 29 Control for 2nd attachment Valves 20a to 29a Control valve operation detecting means 35 Electromagnetic proportional pressure reducing valve for first pump control 36 Electromagnetic proportional pressure reducing valve for first pump control 37 Controller

Claims (1)

In a construction machine equipped with a work attachment driven by a hydraulic actuator for attachment, a hydraulic control circuit of the construction machine,
The attachment hydraulic actuator, and other hydraulic actuators other than the attachment hydraulic actuator;
Variable displacement type first and second pumps that serve as hydraulic supply sources;
A first group consisting of a control valve for the first attachment that controls the oil supply from the first pump to the hydraulic actuator for attachment, and another control valve that controls the oil supply from the first pump to any of the other hydraulic actuators Control valve and
A second group consisting of a control valve for second attachment that controls oil supply from the second pump to the hydraulic actuator for attachment, and another control valve that controls oil supply from the second pump to any other hydraulic actuator Control valve and
Control valve operation detecting means for detecting the operation of each control valve of the first and second groups;
When the attachment hydraulic actuator is driven, the first pump control means for controlling the discharge flow rate of the first pump based on the operation of the first group of control valves, and the second pump of the second group based on the operation of the second group of control valves. A second pump control means for controlling the discharge flow rate,
The first and second pump control means set the discharge flow rate of the first and second pumps to an attachment flow rate that is preset according to the attachment hydraulic actuator when the first and second attachment control valves are single acting. The first and second attachment control valves are linked to the other control valves of the first and second groups, and the attachment flow rate is set in accordance with the other hydraulic actuators. A hydraulic control circuit in a construction machine, wherein each control is performed so that a flow rate is added.

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