JP6614695B2 - Hydraulic actuator control circuit - Google Patents

Description

  The present invention relates to a technical field of a hydraulic actuator control circuit for performing oil supply / discharge control for a hydraulic actuator provided in a construction machine such as a hydraulic excavator.

In general, construction machines such as hydraulic excavators are provided with various hydraulic actuators. As a control circuit for performing oil supply / discharge control for such hydraulic actuators, conventionally, a single spool valve has been used as a hydraulic actuator. Simultaneously performs direction switching control for switching the supply / discharge direction of hydraulic oil to the hydraulic pump, supply flow control for controlling the supply flow rate from the hydraulic pump to the hydraulic actuator, and discharge flow control for controlling the discharge flow rate from the hydraulic actuator to the oil tank. Such a configuration is widely known. However, when the supply flow rate control and the discharge flow rate control are performed with a single spool valve as described above, the relationship between the supply side opening area and the discharge side opening area with respect to the movement position of the spool valve is uniquely determined. Therefore, for example, the supply flow rate and the discharge flow rate are determined according to various work contents such as a single operation of driving a single hydraulic actuator independently, a combined operation of simultaneously driving a plurality of hydraulic actuators, or a light operation and a heavy operation. There is a problem that the relationship between the two cannot be changed and the operability is inferior.
Therefore, conventionally, the oil supply / discharge control for the hydraulic actuator is performed by controlling the supply flow rate from the hydraulic pump to the head side oil chamber and the rod side oil chamber of the hydraulic cylinder. Valve) and four metering valves: head side oil chamber, rod side oil chamber, head side and rod side discharge valve (head end, rod end drain valve) for controlling the discharge flow rate from the oil tank to the oil tank, respectively. A technique is known which is performed by a formed bridge circuit (see, for example, Patent Document 1). In this, the four metering valves are individually operated based on a command from the controller, and thus the relationship between the supply flow rate and the discharge flow rate can be easily changed according to the work contents. can do.
On the other hand, an auxiliary valve having a variable resistance function is arranged on the upstream side of the direction switching valve (spool valve) that performs the above-described direction switching control, supply flow rate control, and discharge flow rate control at the same time. There is also known a technique in which the pressure oil supply to the direction switching valve is controlled in an auxiliary manner in accordance with the work content or the like. (For example, refer to Patent Document 2).

Japanese Patent No. 5214450 JP-A-9-79212

However, as described in Patent Document 1, an oil supply / discharge control for a hydraulic actuator is performed by four metering valves, in addition to the four spools (or poppets) constituting the four metering valves. In addition, four actuators (solenoids in Patent Document 1) for moving each spool are necessary, and there is a problem that the circuit is complicated, the number of components is large, and the cost is high.
On the other hand, although the thing of patent document 2 can control the hydraulic oil distribution and priority to each hydraulic actuator at the time of complex work by an auxiliary valve, supply flow control and discharge flow rate to the hydraulic actuator with one directional switching valve Since the control is performed at the same time as before, the problem that the relationship between the supply flow rate and the discharge flow rate cannot be changed according to the work content is still not solved, and the problem to be solved by the present invention is here. is there.

SUMMARY OF THE INVENTION The present invention was created in view of the above-described circumstances to solve these problems, and the invention of claim 1 is a hydraulic actuator control circuit for performing oil supply / discharge control for a hydraulic actuator. The hydraulic actuator control circuit includes first and second hydraulic pumps, a plurality of hydraulic actuators supplied with pressure oil from at least one of the first and second hydraulic pumps, a flow control valve for controlling the supply flow rate to the hydraulic actuators from the second hydraulic pump, is arranged on the downstream side of the flow rate control valve, from the hydraulic actuator switches the supply and discharge direction of the hydraulic fluid to the hydraulic actuators While controlling the discharge flow rate is controlled and the directional control valve supply flow rate does not control, the bypass flow rate flowing through the first, the oil tank from the second hydraulic pump One, a second bypass valve, while the flow control valve, Ru and control means for controlling the operation of the directional control valve and the bypass valve, the hydraulic actuator is pressure from the first, second both hydraulic pumps Including a large-flow hydraulic actuator supplied with oil, and the flow control valve for the large-flow hydraulic actuator is composed of first and second flow control valves for controlling supply flow from the first and second hydraulic pumps, respectively. The supply flow rates from the first and second flow rate control valves are merged to flow to the direction switching valve, and the control means includes first and second flow rate control valves for a large flow rate hydraulic actuator. In controlling the flow control valve for each hydraulic actuator, the distribution flow obtained by distributing the discharge flow rates of the first and second hydraulic pumps according to the operation amount of each operation tool for the hydraulic actuator is obtained. Each hydraulic actuator based on the flow rate supplied to each hydraulic actuator from the first and second hydraulic pumps calculated based on the pressure difference between the pump pressure of the first and second hydraulic pumps and the load pressure of each hydraulic actuator It is a hydraulic actuator control circuit characterized by controlling a flow control valve for use .
A second aspect of the present invention is the hydraulic actuator control circuit according to the first aspect, wherein the flow control valve is an electromagnetic proportional poppet valve.
A third aspect of the present invention is the hydraulic actuator control circuit according to the first or second aspect, wherein the direction switching valve is a spool valve, and the discharge flow rate from the hydraulic actuator is controlled by a notch formed in the spool valve. It is.
According to a fourth aspect of the present invention, in any one of the first to third aspects, the control means calculates a discharge flow rate from the hydraulic actuator based on an operation amount of the operation tool for the hydraulic actuator, and the calculated discharge amount. A hydraulic actuator control circuit that controls a direction switching valve based on a flow rate and a load pressure of the hydraulic actuator.
A fifth aspect of the present invention is the hydraulic actuator control circuit according to any one of the first to fourth aspects, wherein the hydraulic actuator control circuit controls oil supply / discharge for each hydraulic actuator of a boom cylinder, a stick cylinder, a bucket cylinder, and a swing motor provided in the hydraulic excavator. The hydraulic actuator control circuit is configured to supply the first and second hydraulic pumps and the supply flow rate from the first or second hydraulic pump to the bucket cylinder and the swing motor. Flow control valves for buckets and swings for respectively controlling the flow rate, and flow control valves for the first boom and the first stick for controlling the supply flow rate from the first hydraulic pump to the boom cylinder and the stick cylinder, respectively. A second block that controls the supply flow rate from the second hydraulic pump to the boom cylinder and stick cylinder. Each of the flow control valves for the cylinder and the second stick, and downstream of the flow control valves for the bucket and the swing, respectively, and the supply and discharge directions of the hydraulic oil to the bucket cylinder and the swing motor are switched and the bucket cylinder The directional control valves for the bucket and the swing for controlling the discharge flow rate from the swing motor and the flow control valves for the first and second booms are arranged downstream of the first and second boom flow control valves. It is arranged downstream of the boom direction switching valve that controls the discharge flow from the boom cylinder and the first and second stick flow control valves, and switches the supply and discharge direction of hydraulic oil to the stick cylinder and from the stick cylinder. The directional control valve for the stick that controls the discharge flow rate and the bypass flow rate that flows from the first hydraulic pump to the oil tank A first bypass valve Gosuru a hydraulic actuator control circuit characterized in that it comprises a second bypass valve for controlling the bypass flow rate flowing into the oil tank from the second hydraulic pump.

According to the invention of claim 1, the supply flow rate and the discharge flow rate can be controlled by individual valves, the work efficiency and operability can be improved, the circuit configuration is simplified, and the number of parts is reduced. This can be achieved and contribute to cost reduction.
According to the second aspect of the present invention, a backflow prevention function from the hydraulic actuator to the hydraulic pump side can be provided in addition to the flow rate control function without complicating the valve structure of the flow rate control valve.
By setting it as invention of Claim 3, a direction switching valve can be produced at low cost.
By setting it as invention of Claim 4, highly accurate supply flow rate control can be performed.
By setting it as invention of Claim 5, highly accurate discharge flow rate control can be performed.
By performing the oil supply / discharge control of the large flow rate hydraulic actuator, the supply flow rate control can individually control the supply flow rates from the first and second hydraulic pumps, while switching the direction. Control and discharge flow rate control can be performed with one directional switching valve for one hydraulic actuator, which contributes to the reduction of parts.
According to the invention of claim 7, various operations by the hydraulic excavator can be efficiently performed, and it is possible to contribute to improvement in operability and energy efficiency.

It is a hydraulic circuit diagram of a hydraulic excavator. It is a block diagram which shows control of a controller. It is a block diagram which shows control of the control part for booms. It is a block diagram which shows control of the control part for sticks. It is a block diagram which shows control of the control part for buckets. It is a block diagram which shows control of the control part for turning. It is a block diagram which shows control of the control part for attachments.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a hydraulic circuit diagram of a hydraulic excavator in which a hydraulic actuator control circuit according to the present invention is implemented. In FIG. 1, 1 and 2 are variable displacement type first and second hydraulic pumps, and 3 is an oil tank. 4 is a left travel motor, 5 is a right travel motor, 6 is a boom cylinder, 7 is a stick cylinder, 8 is a bucket cylinder, 9 is a turning motor, and 10 is a hydraulic actuator for attachment (hydraulic motor or hydraulic cylinder).
The boom cylinder 6, the stick cylinder 7, the bucket cylinder 8, the swing motor 9, and the attachment hydraulic actuator 10 correspond to the hydraulic actuator of the present invention. In the following description, the boom cylinder 6, the stick cylinder 7, and the bucket cylinder. 8. The swing motor 9 and the attachment hydraulic actuator 10 may be simply referred to as a hydraulic actuator. Further, the present invention is not implemented in the oil supply / discharge control for the left traveling motor 4 and the right traveling motor 5, and the left traveling motor 4 and the right traveling motor 5 do not correspond to the hydraulic actuator of the present invention.

  The first hydraulic pump 1 is connected to a first pump line 12 via a travel straight travel valve 11 at a first position X, which will be described later, and to a left travel control valve 13. On the other hand, the second hydraulic pump 2 is connected to the second pump line 14 and to the right travel control valve 15 via the travel straight travel valve 11 at the first position X.

  The traveling straight valve 11 is a two-position switching valve that switches between a first position X and a second position Y based on a control signal output from a controller 16 to be described later. The traveling straight valve 11 is a first position. In the state positioned at X, the discharge oil of the first hydraulic pump 1 is supplied to the first pump line 12 and the left travel control valve 13, and the discharge oil of the second hydraulic pump 2 is supplied to the second pump line 14 and the right side. When the traveling straight valve 11 is located at the second position Y, the oil discharged from the first hydraulic pump 1 is supplied to both the left and right traveling control valves. 13 and 15 and the oil discharged from the second hydraulic pump 2 is supplied to both the first and second pump lines 12 and 14. Then, the controller 16 operates when only the left and right traveling operation tools (not shown) are operated, or other hydraulic actuator operation tools (boom, stick, bucket, swivel) other than the traveling operation tool. When only the operation tool for attachment or attachment (not shown) is operated, the traveling straight valve 11 is controlled to be positioned at the first position X. On the other hand, when both the left and right traveling operation tools are operated to perform straight traveling, and the other hydraulic actuator operation tools are operated at the same time, a control signal is output to set the traveling straight valve 11 to the second position Y. Switch. As a result, when only the left and right traveling operation tools are operated, the travel straight-advancing valve 11 located at the first position X causes the discharged oil of the first and second hydraulic pumps 1 and 2 to be left and right. Are supplied to the left and right traveling motors 4 and 5 through the traveling control valves 13 and 15, respectively, so that the flow rates supplied to both the traveling motors 4 and 5 can be made equal. When another hydraulic actuator operation tool is operated at the same time as the travel operation tool, the discharge flow rate of the first hydraulic pump 1 is distributed only by the left and right travel motors 4 and 5 to both travel motors 4 and 5. The supply flow rate can be made equal. In the following description, when the traveling straight valve 11 is located at the first position X, that is, the discharge oil of the first hydraulic pump 1 is supplied to the first pump line 12 and the left traveling control valve 13, The case where the oil discharged from the second hydraulic pump 2 is supplied to the second pump line 14 and the right traveling control valve 15 will be described.

The left and right traveling control valves 13 and 15 are pilot-operated three-position switching valves that respectively perform oil supply / discharge control for the left and right traveling motors 4 and 5, and control signals output from the controller 16. Based on this, there are provided pilot ports 13a, 13b, 15a, 15b on the forward side and the reverse side connected to an electromagnetic proportional valve (not shown) that outputs a pilot pressure based on the pilot pressure. The left and right traveling control valves 13 and 15 supply power to the left and right traveling motors 4 and 5 when no pilot pressure is input to the forward and reverse pilot ports 13a, 13b, 15a and 15b. Although it is located at the neutral position N where exhaust control is not performed, the first hydraulic pump is driven to drive the left traveling motor 4 and the right traveling motor 5 forward by inputting pilot pressure to the forward pilot ports 13a and 15a. 1. The forward side that supplies the oil discharged from the second hydraulic pump 2 to one of the ports 4 a and 5 a of the left traveling motor 4 and the right traveling motor 5 and flows the oil discharged from the other ports 4 b and 5 b to the oil tank 3. The left traveling motor 4 and the right traveling motor are located at the operating position X and the pilot pressure is input to the reverse pilot ports 13b and 15ba. The oil discharged from the first hydraulic pump 1 and the second hydraulic pump 2 is supplied to the other ports 4b and 5b of the left traveling motor 4 and the right traveling motor 5 and discharged from one port 4a and 5a. Although it is configured to be located at the reverse operation position Y for flowing oil into the oil tank 3, the left travel motor 4 and the right travel motor 5 when it is located at the forward operation position X or the reverse operation position Y. The supply flow rate to the engine increases and decreases according to the increase and decrease of the pilot pressure output from the electromagnetic proportional valve to the forward or reverse pilot ports 13a, 13b, 15a and 15b. Then, when the left and right traveling operation tools are operated, the controller 16 controls the electromagnetic proportional valve so as to output a pilot pressure that increases or decreases in accordance with the operation amount of the traveling operation tool. Accordingly, the left and right traveling motors 4 and 5 can be driven at a speed corresponding to the operation amount of the traveling operation tool.
The left and right traveling control valves 13 and 15 do not correspond to the flow control valve and the direction switching valve of the present invention. Incidentally, the operability when the left and right traveling motors 4 and 5 are independently or combined with other hydraulic actuators is ensured by the traveling straight valve 11 described above.

  On the other hand, a first boom supply oil passage 17, a first stick supply oil passage 18, a bucket supply oil passage 19, and a first attachment supply oil passage 20 are branched from the first pump line 12. In addition, a second boom supply oil passage 21, a second stick supply oil passage 22, a turning supply oil passage 23, and a second attachment supply oil passage 24 are branched from the second pump line 14. . The supply oil passages 17 to 24 are respectively provided with a first boom flow control valve 25, a first stick flow control valve 26, a bucket flow control valve 27, a first attachment flow control valve 28, and a second. A boom flow control valve 29, a second stick flow control valve 30, a turning flow control valve 31, and a second attachment flow control valve 32 are provided. The first flow control valves 25 to 32 for the first boom, the first stick, the bucket, the first attachment, the second boom, the second stick, the turning, and the second attachment are the Corresponds to a flow control valve. The flow control valves 25, 26, 28 for the first boom, the first stick, and the first attachment correspond to the first flow control valve of the present invention, and are for the second boom, the second stick, Each flow control valve 29, 30, 32 for two attachments corresponds to the second flow control valve of the present invention.

  The flow control valves 25 to 32 for the first boom, the first stick, the bucket, the first attachment, the second boom, the second stick, the turning, and the second attachment are output from the controller 16. The first proportional flow rate control valve 25 controls the supply flow rate to the corresponding hydraulic actuators 6 to 10 based on the control signal. Is supplied to a boom direction switching valve 33 which will be described later. Further, the first stick flow control valve 26 controls the supply flow rate from the first hydraulic pump 1 to the stick cylinder 7 to flow to the stick direction switching valve 34. Further, the bucket flow control valve 27 controls the supply flow rate from the first hydraulic pump 1 to the bucket cylinder 8 to flow to the bucket direction switching valve 35. The first attachment flow control valve 28 controls the flow rate supplied from the first hydraulic pump 1 to the attachment hydraulic actuator 10 and causes the flow to the attachment direction switching valve 37. Further, the second boom flow control valve 29 controls the supply flow rate from the second hydraulic pump 2 to the boom cylinder 6 and causes the flow to the boom direction switching valve 33. Further, the second stick flow control valve 30 controls the supply flow rate from the second hydraulic pump 2 to the stick cylinder 7 to flow to the stick direction switching valve 34. Further, the turning flow control valve 31 controls the supply flow rate from the second hydraulic pump 2 to the turning motor 9 to flow to the turning direction switching valve 36. Further, the second attachment flow control valve 32 controls the flow rate supplied from the second hydraulic pump 2 to the attachment hydraulic actuator 10 to flow to the attachment direction switching valve 37. Furthermore, each of these flow control valves 25-32 has a backflow prevention function, so that backflow from the corresponding hydraulic actuators 6-10 to the first and second pump lines 12, 14 is prevented. .

The boom direction switching valve 33 is disposed downstream of the first boom flow control valve 25 and the second boom flow control valve 29, and the first and second boom flow control valves 25, The flow rates from 29 are combined and supplied. Further, the stick direction switching valve 34 is arranged downstream of the first stick flow control valve 26 and the second stick flow control valve 30, and the first and second stick flow control valves 26, 30. The flow rates from are combined and supplied. Further, the bucket direction switching valve 35 is arranged on the downstream side of the bucket flow control valve 27, and the flow rate from the bucket flow control valve 27 is supplied. Further, the turning direction switching valve 36 is arranged on the downstream side of the turning flow control valve 31, and the flow rate from the turning flow control valve 31 is supplied. Further, the attachment direction switching valve 37 is disposed downstream of the first attachment flow control valve 28 and the second attachment flow control valve 32, and the first and second attachment flow control valves 28, 32. The flow rates from are combined and supplied.
The direction switching valves 33 to 37 for the boom, the stick, the bucket, the swivel, and the attachment are, as will be described later, the first boom, the first stick, the bucket, the first attachment, The flow supplied from the flow control valves 25 to 32 for the second boom, the second stick, the swing, and the second attachment is used as it is, the boom cylinder 6, the stick cylinder 7, the bucket cylinder 8, the swing motor 9, and the attachment hydraulic pressure. The boom 10 is configured to flow through the actuator 10, so that the oil discharged from the first and second hydraulic pumps 1 and 2 is flowed into the boom cylinder 6 by the first and second boom flow control valves 25 and 29. It is supplied via the boom direction switching valve 33 after being controlled, and is discharged to the stick cylinder 7 from the first and second hydraulic pumps 1 and 2. Is supplied through the stick direction switching valve 34 after the flow rate is controlled by the first and second stick flow control valves 26 and 30, and the bucket cylinder 8 is supplied with the discharge oil of the first hydraulic pump 1. The flow rate is controlled by the bucket flow control valve 27 and then supplied via the bucket direction switching valve 35, and the oil discharged from the second hydraulic pump 2 is supplied to the swing motor 9 by the swing flow control valve 31. After being controlled, it is supplied via the turning direction switching valve 36, and the discharge oil of the first and second hydraulic pumps 1 and 2 is supplied to the attachment hydraulic actuator 10 through the first and second attachment flow control. The flow rate is controlled by the valves 28 and 32 and then supplied via the attachment direction switching valve 37. The boom cylinder 6, stick cylinder 7, and attachment hydraulic actuator 10 are hydraulic actuators supplied with pressure oil from both the first and second hydraulic pumps 1 and 2. It corresponds to. Moreover, each direction switching valve 33-37 for the said boom, stick, bucket, turning, and attachment is equivalent to the direction switching valve of this invention.

Further, the details of the direction switching valves 33 to 37 for the boom, the stick, the bucket, the turning, and the attachment will be described. The direction switching valve 33 for the boom, the stick, the bucket, the turning, and the attachment. ˜37 are spool valves that are pilot operated by electromagnetic proportional valves 40a, 40b to 44a, 44b (not shown in FIG. 1) that output pilot pressure based on a control signal output from the controller 16. As will be described later, the hydraulic actuators 6 to 10 (the boom cylinder 6, the stick cylinder 7, the bucket cylinder 8, the swing motor 9, and the attachment actuator 10) are switched in the hydraulic oil supply / discharge direction, and the hydraulic actuator 6 Configured to control the discharge flow rate from -10 That.
First, the boom direction switching valve 33 will be described. The boom direction switching valve 33 includes pilot ports 33a and 33b connected to the boom expansion side electromagnetic proportional valve 40a and the boom reduction side electromagnetic proportional valve 40b. Yes. When the control signal for pilot pressure output is not output from the controller 16 to the boom expansion-side electromagnetic proportional valve 40a and the boom reduction-side electromagnetic proportional valve 40b, the first and second boom flow control valves 25, The oil supplied from 29 is not supplied to the head side oil chamber 6a and the rod side oil chamber 6b of the boom cylinder 6, and the oil discharged from the head side oil chamber 6a and the rod side oil chamber 6b is not allowed to flow into the oil tank 3. Although it is located at the neutral position N, it is supplied from the first and second boom flow control valves 25 and 29 by outputting a control signal for pilot pressure output from the controller 16 to the boom expansion-side electromagnetic proportional valve 40a. The pump flow rate to be supplied is supplied to the head side oil chamber 6a and the exhaust oil from the rod side oil chamber 6b is switched to the extension side operating position X which flows into the oil tank 3, and By supplying a pilot pressure output control signal to the side electromagnetic proportional valve 40b, the pump flow rate supplied from the first and second boom flow rate control valves 25, 29 is supplied to the rod side oil chamber 6b, and A part of the oil discharged from the head side oil chamber 6 a is supplied to the rod side oil chamber 6 b, and the surplus portion is switched to the reduction side operation position Y that flows into the oil tank 3. The opening amount of the boom direction switching valve 33 at the extension side and reduction side operation positions X and Y is from the first and second boom flow control valves 25 and 29 to the head side oil chamber 6a of the boom cylinder 6 and the rod side. The opening area of the supply side valve passage for supplying the pump flow rate to the oil chamber 6b is set sufficiently large with respect to the opening areas of the first and second boom flow control valves 25, 29. The supply flow rate controlled by the second boom flow control valves 25 and 29 is supplied as it is to the head-side oil chamber 6a and the rod-side oil chamber 6b. On the other hand, the opening area of the discharge side valve passage (notch formed in the boom direction switching valve 33) for discharging the oil from the head side oil chamber 6a and the rod side oil chamber 6b of the boom cylinder 6 is adjusted from the controller 16 to the boom. Increase / decrease control is performed based on command values output to the expansion-side electromagnetic proportional valve 40a and the boom reduction-side electromagnetic proportional valve 40b, and the head side is controlled by increasing / decreasing the opening area of the discharge-side valve path of the boom direction switching valve 33. The discharge flow rate from the oil chamber 6a and the rod-side oil chamber 6b to the oil tank 3 is controlled to increase or decrease. Thus, the boom direction switching valve 33 switches the supply / discharge direction of the hydraulic oil to / from the boom cylinder 6 and controls the discharge flow rate from the boom cylinder 6. The supply flow rate to the cylinder 6 is not controlled.

  The stick direction switching valve 34, the bucket direction switching valve 35, the turning direction switching valve 36, and the attachment direction switching valve 37 are the same as the boom direction switching valve 33. The stick direction switching valve 34 includes a stick expansion side electromagnetic proportional valve 41a and a stick reduction side electromagnetic proportional valve 41b, and the bucket direction switching valve 35 includes a bucket expansion side electromagnetic proportional valve 42a and a bucket reduction side electromagnetic proportional valve. 42b, the turning direction switching valve 36 is pilot-operated by the left-turning electromagnetic proportional valve 43a and the right-turning electromagnetic proportional valve 43b, and the attachment-direction switching valve 37 is pilot-operated by the attachment electromagnetic proportional valves 44a and 44b, respectively. The neutral position N is switched to the operating position X or Y, and the opening amount of the operating positions X and Y is the first The flow control valves 26, 30, 27, 31, 28, 32 for the second stick, bucket, swivel, first and second attachment to stick cylinder 7, bucket cylinder 8, swivel motor 9, and attachment hydraulic pressure. The opening area of the supply side valve passage that supplies the pump flow rate to the actuator 10 is set sufficiently large with respect to the opening area of each flow control valve 26, 30, 27, 31, 28, 32. The supply flow rate controlled by the valves 26, 30, 27, 31, 28, 32 is supplied as it is to the stick cylinder 7, bucket cylinder 8, swing motor 9, and attachment hydraulic actuator 10. Further, the opening area of the discharge side valve passage (notch) through which the oil discharged from the stick cylinder 7, the bucket cylinder 8, the swing motor 9, and the attachment hydraulic actuator 10 flows to the oil tank 3 is determined by the controller 16. Increase / decrease control is performed based on the control signals output to 41a, 41b to 44a, 44b, and the stick cylinder 7, bucket cylinder 8, swing motor 9, and attachment hydraulic actuator 10 are controlled by increase / decrease control of the opening area of these discharge side valve passages. The discharge flow rate from is increased or decreased. As a result, the stick direction switching valve 34, the bucket direction switching valve 35, the turning direction switching valve 36, and the attachment direction switching valve 37 are respectively the stick cylinder 7, the bucket cylinder 8, the turning motor 9, and the attachment hydraulic actuator 10. The hydraulic oil supply / discharge direction is switched, and the discharge flow rate from the stick cylinder 7, bucket cylinder 8, turning motor 9, and attachment hydraulic actuator 10 is controlled. The control is not performed on the flow rate of supply to the cylinder 7, the bucket cylinder 8, the swing motor 9, and the attachment hydraulic actuator 10.

  Further, 45 and 46 are first and second bypass oil passages branched from the first and second pump lines 12 and 14 respectively to reach the oil tank 3, and these first and second bypass oil passages 45, First and second bypass valves 47 and 48 are arranged at 46, respectively. The first and second bypass valves 47 and 48 are spool valves that open and close the first and second bypass oil passages 45 and 46 based on a control signal output from the controller 16. By increasing or decreasing the opening area of the bypass valves 47 and 48 based on the command value output from the controller 16, the bypass flow rate flowing from the first and second hydraulic pumps 1 and 2 to the oil tank 3 is increased or decreased. It is like that. By increasing or decreasing the bypass flow rate, the discharge flow rates of the first and second hydraulic pumps 1 and 2 can be supplied to the flow rate control valves 25 to 32 without excess or deficiency.

  On the other hand, as shown in the block diagram of FIG. 2, the controller (corresponding to the control means of the present invention) 16 detects the operation direction and the operation amount of the boom cylinder operation tool on the input side. , Stick operation detecting means 51 for detecting the operation direction and operation amount of the stick operation tool, operation detection means 52 for bucket detecting the operation direction and operation amount of the bucket operation tool, operation direction and operation of the turning operation tool A turning operation detecting means 53 for detecting the amount, an operation direction detecting means 54 for detecting the operation direction and the operation amount of the attachment operating tool, a first pump pressure sensor 55 for detecting the discharge pressure of the first hydraulic pump 1, A second pump pressure sensor 56 for detecting the discharge pressure of the two hydraulic pumps 2 and a boom pressure sensor 57 for detecting the load pressure of the boom cylinder 6 Stick pressure sensor 58 for detecting the load pressure of the stick cylinder 7, bucket pressure sensor 59 for detecting the load pressure of the bucket cylinder 8, turning pressure sensor 60 for detecting the load pressure of the turning motor 9, and attachment hydraulic actuator 10 An attachment pressure sensor 61 for detecting the load pressure of the first boom, the first boom, the first stick, the bucket, the first attachment, the second boom, and the second stick are connected to the output side. , Swiveling, second attachment flow control valves 25-32, boom, stick for pilot operation of the boom, stick, bucket, swivel, attachment directional control valves 33-37 , 40b-44a, 4 proportional solenoid valves for buckets, swivels, and attachments b, the first and second bypass valves 47, 48, etc. are connected, and operating speed tables 62 to 66 for boom, stick, bucket, swivel, and attachment, which will be described later, boom, stick , Bucket, swivel, attachment bypass tables 67-71, pump flow distribution calculation unit 72, bypass control unit 73, boom, stick, bucket, swivel, attachment control units 74 ˜78 etc., and oil supply / discharge control for the boom cylinder 6, stick cylinder 7, bucket cylinder 8, swing motor 9, attachment hydraulic actuator 10, and first and second bypass oil passages 45, 46. The flow rate is controlled. The controller 16 also performs switching control of the traveling straight valve 11 and oil supply / discharge control for the left and right traveling motors 4 and 5 as described above, but description of these controls is omitted here.

Next, the control performed by the controller 16 will be described based on the block diagram of FIG.
First, when an operation signal is input from the boom operation detection means 50, the controller 16 inputs the operation signal to the boom operation speed table 62 and the boom bypass table 67. The boom operation speed table 62 stores a table showing the relationship between the operation signal of the boom operation tool and the operation speed of the boom cylinder 6, and corresponds to the operation amount of the boom operation tool using the table. The obtained operation speed of the boom cylinder 6 is obtained, and the obtained operation speed is output to the pump flow rate distribution calculating unit 72. The boom bypass table 67 stores a table showing the relationship between the operation signal of the boom operation tool and the spool movement strokes of the first and second bypass valves 47, 48. The movement strokes of the first and second bypass valves 47 and 48 corresponding to the operation amount of the operation tool are obtained, and the obtained movement strokes are output to the bypass control unit 73.
Similarly, when an operation signal is input from each of the operation detection means 51 to 54 for stick, bucket, swivel, and attachment, the controller 16 sends the operation signal to the stick, bucket, swivel, and attachment. The operation speed tables 63 to 66 and the bypass tables 68 to 71 are used. The operation speed tables 63 to 66 for the stick, bucket, swivel, and attachment are the operation signals of the stick, bucket, swivel, and attachment operation tools and the stick cylinder 7, bucket cylinder 8, swivel motor 9, A table showing the relationship with the operating speed of the attachment hydraulic actuator 10 is stored, and using these tables, each hydraulic actuator (stick cylinder 7, bucket cylinder 8, swing motor 9, attachment) corresponding to the operation tool operation amount is stored. The operation speed of the hydraulic actuator 10) is obtained, and the obtained operation speed is output to the pump flow rate distribution calculation unit 72. The bypass table 67 for sticks, buckets, swivels, and attachments has an operation signal for the stick, bucket, swivel, and attachment operation tools and spool movements of the first and second bypass valves 47 and 48. A table indicating the relationship with the stroke is stored, and using the table, the movement strokes of the first and second bypass valves 47 and 48 corresponding to the operation amount of each operation tool are obtained, and the obtained movement stroke is calculated. Output to the bypass control unit 73.

  Thus, the pump flow rate distribution calculating unit 72 includes the boom cylinder 6, the stick cylinder 7, and the bucket cylinder obtained from the operating speed tables 62 to 66 for the boom, stick, bucket, swivel, and attachment. 8, the operation speeds of the swing motor 9 and the attachment hydraulic actuator 10 are input. The pump flow rate distribution calculation unit 72 determines the discharge flow rates of the first and second hydraulic pumps 1 and 2 based on these input values. Distributing flow rate from the first and second hydraulic pumps 1 and 2 to the boom cylinder 6, stick cylinder 7, bucket cylinder 8, swing motor 9, and attachment hydraulic actuator 10 so as to be distributed at a ratio corresponding to the operation amount of the operating tool. Is calculated. The calculated distribution flow rate is output to the control units 74 to 78 for the boom, the stick, the bucket, the turning, and the attachment. The control of these control units 74 to 78 will be described later.

  On the other hand, the bypass control unit 73 has movement strokes of the first and second bypass valves 47 and 48 obtained by the bypass tables 67 to 71 for boom, stick, bucket, swivel, and attachment. The bypass control unit 73 calculates the movement strokes of the first and second bypass valves 47 and 48 to be the total value or the maximum value of the inputted movement strokes based on these input values. To do. Then, control signals are output to the first and second bypass valves 47 and 48 so that the calculated movement stroke is achieved, so that the flow control of the first and second bypass oil passages 45 and 46 is performed. It has become.

  Next, the control of the boom control unit 74 will be described based on the block diagram shown in FIG. 3. The boom control unit 74 includes a first supply flow rate calculation unit 80, a second supply flow rate calculation unit 81, and a discharge. The flow rate calculation unit 82, the first flow rate control valve command value table 83, the second flow rate control valve command value table 84, the direction switching valve stroke table 85, the correction calculation unit 86, and the electromagnetic proportional valve command value table 87 are configured. Yes.

  The boom control unit 74 receives signals from the pump flow rate distribution calculation unit 72, the first pump pressure sensor 55, the second pump pressure sensor 56, and the boom pressure sensor 57, and based on these input signals. The oil supply / discharge control for the boom cylinder 6 is performed. In this case, first, the value of the distribution flow rate to the boom cylinder 6 calculated by the pump flow rate distribution calculation unit 72 is used as the first supply flow rate calculation unit 80 and the second supply. Input to the flow rate calculation unit 81 and the discharge flow rate calculation unit 82. The first supply flow rate calculation unit 80 calculates the supply flow rate from the first hydraulic pump 1 to the boom cylinder 6 based on the input value of the distribution flow rate to the boom cylinder 6, and calculates the calculated value as the first flow rate. Output to the flow control valve command value table 83. The second supply flow rate calculation unit 81 calculates the supply flow rate from the second hydraulic pump 2 to the boom cylinder 6 and outputs the calculated value to the second flow rate control valve command value table 84. Further, the discharge flow rate calculation unit 82 calculates the discharge flow rate from the boom cylinder 6 and outputs the calculated value to the direction switching valve stroke table 85.

  The first flow control valve command value table 83 includes a supply flow rate from the first hydraulic pump 1 to the boom cylinder 6, a differential pressure between the pump pressure of the first hydraulic pump 1 and the load pressure of the boom cylinder 6, A table showing the relationship with the command value for the boom flow control valve 25 is stored. The first flow control valve command value table 83 inputs the detection values of the first pump pressure sensor 55 and the boom pressure sensor 57, and the difference between the pump pressure of the first hydraulic pump 1 and the load pressure of the boom cylinder 6 is input. The first boom flow rate is calculated using the table based on the pressure difference and the supply flow rate from the first hydraulic pump 1 to the boom cylinder 6 calculated by the first supply flow rate calculation unit 80. A command value for the control valve 25 is obtained. And the command value calculated | required by this 1st flow control valve command value table 83 is output to the flow control valve 25 for 1st booms, and, thereby, the supply flow volume from the 1st hydraulic pump 1 to the boom cylinder 6 is controlled. It is like that.

  The second flow control valve command value table 84 includes a supply flow rate from the second hydraulic pump 2 to the boom cylinder 6, a differential pressure between the pump pressure of the second hydraulic pump 2 and the load pressure of the boom cylinder 6, A table showing the relationship with the command value for the two-boom flow control valve 29 is stored. Then, the second flow control valve command value table 84 receives the detection values of the second pump pressure sensor 56 and the boom pressure sensor 57 and inputs the difference between the pump pressure of the second hydraulic pump 2 and the load pressure of the boom cylinder 6. The second boom flow rate is calculated using the table based on the differential pressure and the supply flow rate from the second hydraulic pump 2 to the boom cylinder 6 calculated by the second supply flow rate calculation unit 81. A command value for the control valve 29 is obtained. Then, the command value obtained from the second flow rate control valve command value table 84 is output to the second boom flow rate control valve 29, whereby the supply flow rate from the second hydraulic pump 2 to the boom cylinder 6 is controlled. It is like that.

  On the other hand, the direction switching valve stroke table 85 stores a table showing the relationship between the discharge flow rate from the boom cylinder 6 and the spool movement stroke of the boom direction switching valve 33. The direction switching valve stroke table 85 obtains the movement stroke of the boom direction switching valve 33 using the table based on the discharge flow rate of the boom cylinder 6 calculated by the discharge flow rate calculation unit 82, The movement stroke is output to the correction calculation unit 86.

  The correction calculation unit 86 inputs the load pressure of the boom cylinder 6 detected by the boom pressure sensor 57, and is used for the boom obtained by the direction switching valve stroke table 85 based on the load pressure of the boom cylinder 6. The movement stroke of the direction switching valve 33 is corrected, and the corrected movement stroke is output to the electromagnetic proportional valve command value table 87.

  The electromagnetic proportional valve command value table 87 includes a movement stroke of the boom direction switching valve 33 and command values for the boom electromagnetic proportional valves 40a and 40b (the boom expansion side electromagnetic proportional valve 40a and the boom reduction side electromagnetic proportional valve 40b). A table showing the relationship is stored. Based on the movement stroke of the boom direction switching valve 33 corrected by the correction calculation unit 86, command values for the boom electromagnetic proportional valves 40a and 40b are obtained using the table. Then, the command value obtained from the electromagnetic proportional valve command value table 87 is the boom expansion side, the reduction side electromagnetic proportional valves 40a, 40b (when the boom operation tool is operated to the boom raising side, the boom expansion side electromagnetic When the proportional valve 40a and the boom operation tool are operated to the boom lowering side, the proportional valve 40a is output to the boom extension side electromagnetic proportional valve 40a), whereby the discharge flow rate from the boom cylinder 6 is controlled. .

Next, the control units 75 to 78 for the stick, bucket, swivel, and attachment will be described. Since the configuration and control of these control units 75 to 78 are the same as the boom control unit 74 described above, Briefly described.
First, as shown in the block diagram of FIG. 4, the stick control unit 75 has a first supply flow rate calculation unit 80, a second supply flow rate calculation unit 81, a discharge flow rate calculation unit 82, as in the boom control unit 74. A first flow control valve command value table 83, a second flow control valve command value table 84, a direction switching valve stroke table 85, a correction calculation unit 86, and an electromagnetic proportional valve command value table 87 are provided. According to the command values output from the flow control valve command value tables 83 and 84 to the first and second stick flow control valves 26 and 30, the supply flow rate from the first and second hydraulic pumps 1 and 2 to the stick cylinder 7 is changed. Controlled from the stick cylinder 7 according to the command values output from the proportional solenoid valve command value table 87 to the stick expansion side and reduction side solenoid proportional valves 41a and 41b. Out flow rate is controlled.

  Further, as shown in the block diagram of FIG. 5, the bucket control unit 76 has one bucket flow control valve 27 that controls the supply flow rate to the bucket cylinder 8. Only one command value table 89 is provided, but other than the boom control unit 74, the discharge flow rate calculation unit 82, the direction switching valve stroke table 85, the correction calculation unit 86, and the electromagnetic proportional valve command value table are the same. 87, the supply flow rate from the first hydraulic pump 1 to the bucket cylinder 8 is controlled by the command value output from the flow control valve command value table 89 to the bucket flow control valve 27, and is proportional to the electromagnetic proportionality. Discharge from the bucket cylinder 8 according to the command values output from the valve command value table 87 to the bucket expansion side and reduction side electromagnetic proportional valves 42a and 42b. The amount is controlled.

  Further, as shown in the block diagram of FIG. 6, the turning control unit 77 has a single turning flow control valve 31 that controls the flow rate supplied to the turning motor 9, similarly to the bucket control unit 76. , Only one supply flow rate calculation unit 88 and one flow rate control valve command value table 89 are provided. Other than the boom control unit 74, the discharge flow rate calculation unit 82, the direction switching valve stroke table 85, and the correction are provided. A calculation unit 86 and an electromagnetic proportional valve command value table 87 are provided, and the command value output from the flow control valve command value table 89 to the turning flow control valve 31 is used to send the second hydraulic pump 2 to the turning motor 8. The supply flow rate is controlled, and discharge from the turning motor 8 is performed according to the command values output from the electromagnetic proportional valve command value table 87 to the left turn and right turn electromagnetic proportional valves 43a and 43b. The amount is controlled.

  Further, as shown in the block diagram of FIG. 7, the attachment control unit 78 is similar to the boom control unit 74, the first supply flow rate calculation unit 80, the second supply flow rate calculation unit 81, the discharge flow rate calculation unit 82, The first flow control valve command value table 83, the second flow control valve command value table 84, the direction switching valve stroke table 85, the correction calculation unit 86, and the electromagnetic proportional valve command value table 87 are provided. Supply flow rates from the first and second hydraulic pumps 1 and 2 to the attachment hydraulic actuator 10 according to the command values output from the control valve command value tables 83 and 84 to the first and second attachment flow control valves 28 and 32. Are controlled by the command values output from the electromagnetic proportional valve command value table 87 to the electromagnetic proportional valves for attachment 44a, 44b. Discharge flow rate from the hydraulic actuator 10 is controlled.

  In this embodiment configured as described, hydraulic actuator control for performing oil supply / discharge control on the hydraulic actuators 6 to 10 (the boom cylinder 6, the stick cylinder 7, the bucket cylinder 8, the swing motor 9, and the attachment hydraulic actuator 10). The circuit includes hydraulic pumps 1 and 2 (first and second hydraulic pumps 1 and 2) and flow control valves 25 to 32 (first pumps) that control the supply flow rate from the hydraulic pumps 1 and 2 to the hydraulic actuators 6 to 10. One boom flow control valve 25, first stick flow control valve 26, bucket flow control valve 27, first attachment flow control valve 28, second boom flow control valve 29, second stick flow control valve 30 The flow control valve 31 for turning, the flow control valve 32 for the second attachment, and the downstream of the flow control valves 25-32. Direction switching valves 33 to 37 that switch the supply and discharge directions of hydraulic oil to and from the pressure actuators 6 to 10 and control the discharge flow rate from the hydraulic actuators 6 to 10 (the direction switching valve 33 for the boom, the direction switching valve 34 for the stick, and the bucket Direction switching valve 35, turning direction switching valve 36, attachment direction switching valve 37), and bypass valves 47, 48 (first and second bypass valves) for controlling the bypass flow rate flowing from the hydraulic pumps 1, 2 to the oil tank 3. 47, 48), and the flow rate control valves 25 to 32, the direction switching valves 33 to 37, and the controller (control means) 16 for controlling the operation of the bypass valves 47 and 48. Thus, the hydraulic oil supplied from the hydraulic pumps 1 and 2 is supplied to the hydraulic actuators 6 to 10 via the direction switching valves 33 to 37 for switching the supply / discharge direction after the flow rate is controlled by the flow control valves 25 to 32. On the other hand, the oil discharged from the hydraulic actuators 6 to 10 is discharged to the oil tank 3 with the flow rate controlled by the direction switching valves 33 to 37 for switching the supply and discharge directions.

  As a result, the supply flow rate from the hydraulic pumps 1 and 2 to the hydraulic actuators 6 to 10 is controlled by the flow rate control valves 25 to 32, while the discharge flow rate from the hydraulic actuators 6 to 10 is controlled by the direction switching valves 33 to 37. Therefore, the supply flow rate control and the discharge flow rate control are performed by individual valves controlled by the controller 16, so that the hydraulic actuators 6 to 10 are driven independently. It is possible to easily change the relationship between the supply flow rate and the discharge flow rate in correspondence with various work contents such as complex work for driving a plurality of hydraulic actuators 6 to 10 simultaneously, or light work and heavy work, and work efficiency Can greatly contribute to the improvement of operability and energy efficiency. In addition, since the supply flow rate control and the discharge flow rate control can be performed individually as described above, the direction switching valves 33 to 37 have two functions of the direction switching control and the discharge flow rate control. Compared with the case where oil supply / discharge control is performed using four metering valves, the circuit configuration can be simplified and the number of parts can be reduced, thereby contributing to cost reduction.

  Furthermore, in this thing, the said flow control valves 25-32 are electromagnetic proportional type poppet valves, Comprising the valve structure by comprising the flow control valves 25-32 using a poppet valve in this way. In addition, in addition to the flow rate control function, a backflow prevention function from the hydraulic actuators 6 to 10 to the hydraulic pumps 1 and 2 can be provided.

  The direction switching valves 33 to 37 are spool valves, and are configured to control the discharge flow rate from the hydraulic actuator by a notch formed in the spool valve. In this case, the direction switching valves are discharged. Since only the flow rate is controlled, it takes time and effort to adjust the relationship between the supply flow rate and the discharge flow rate as in the case where the conventional single spool valve performs the direction switching control, the supply flow rate control, and the discharge flow rate control. The structure is simple and can be manufactured at low cost.

  Furthermore, in this, the controller 16 calculates the supply flow rate to the hydraulic actuators 6 to 6 based on the operation amount of the operating tool operated to drive the hydraulic actuators 6 to 10, and the calculated supply flow rate, The flow control valves 25 to 32 are controlled based on the differential pressure between the pump pressure and the load pressure of the hydraulic actuators 6 to 10, whereby the pump pressure and the load pressure of the hydraulic actuators 6 to 10 fluctuate. However, highly accurate supply flow rate control can be performed without being affected by the fluctuation.

  The controller 16 calculates the discharge flow rate from the hydraulic actuators 6 to 10 based on the operation amount of the operation tool operated to drive the hydraulic actuators 6 to 10, and the calculated discharge flow rate and the hydraulic actuator 6. The direction switching valves 33 to 37 are controlled on the basis of the load pressure of 10 to 10, so that highly accurate discharge flow rate control according to the load pressure of the hydraulic actuators 6 to 10 can be performed.

  The hydraulic actuator control circuit of the present embodiment includes the first and second hydraulic pumps 1 and 2 and a large flow hydraulic actuator that is supplied with pressure oil from both the first and second hydraulic pumps 1 and 2. 6, 7, 10 (boom cylinder 6, stick cylinder 7, attachment hydraulic actuator 10), and the flow control valves for the large flow hydraulic actuators 6, 7, 10 are first and second hydraulic pumps. First and second flow control valves 25, 29, 26, 30, 28 and 32 (first boom flow control valve 25, second boom flow control valve 29, first A flow control valve 26 for one stick, a flow control valve 30 for a second stick, a flow control valve 28 for a first attachment, and a flow control valve 32 for a second attachment. Direction switching valves 33, 34, 37 (boom direction switching valve 33, stick direction switching valve 34, attachment direction) by merging the supply flow rates from the second flow control valves 25, 29, 26, 30, 28, 32 The flow is made to flow through the switching valve 37). Thus, when performing oil supply / discharge control of the large-flow hydraulic actuators 6, 7, 10 supplied with pressure oil from both the first and second hydraulic pumps 1, 2. As for the supply flow rate control, the supply flow rates from the first and second hydraulic pumps 1 and 2 can be individually controlled by the first and second flow control valves 25, 29, 26, 30, 28, and 32, respectively. On the other hand, the direction switching control and the discharge flow rate control can be performed by one directional switching valve 33, 34, 37 for one hydraulic actuator 6, 7, 10, which can contribute to the reduction of parts.

  Further, in the present embodiment, the present invention is implemented in the oil supply / discharge control for the boom cylinder 6, the stick cylinder 7, the bucket cylinder 8, and the swing motor 9 provided in the hydraulic excavator. 2 and the supply flow rate from the first or second hydraulic pump 1, 2 to the bucket cylinder 8 and the swing motor 9 (in this embodiment, the supply flow rate from the first hydraulic pump 1 to the bucket cylinder 8) , And the flow rate control valves 27 and 31 for swing, which respectively control the supply flow rate from the second hydraulic pump 2 to the swing motor 9, and the first hydraulic pump 1 to the boom cylinder 6 and stick cylinder 7. The first boom and first stick flow control valves 25 and 26 for controlling the supply flow rate, the second hydraulic pump 2 to the boom cylinder 6, the stick The second boom and second stick flow control valves 29 and 30 that respectively control the flow rate supplied to the solder 7 and the bucket and swirl flow control valves 27 and 31 are arranged on the downstream side. The bucket direction control valves 35 and 36 for switching the supply and discharge directions of hydraulic oil to and from the bucket cylinder 8 and the swing motor 9 and controlling the discharge flow rate from the bucket cylinder 8 and the swing motor 9, respectively, And a boom direction switching valve 33 which is disposed downstream of the second boom flow control valves 25 and 29 and switches the supply / discharge direction of hydraulic oil to / from the boom cylinder 6 and controls the discharge flow rate from the boom cylinder 6; It is arranged on the downstream side of the first and second stick flow control valves 26, 30 and switches the supply / discharge direction of hydraulic oil to / from the stick cylinder 7. Direction switch valve 34 for controlling the discharge flow rate from the back cylinder 7, the first bypass valve 47 for controlling the bypass flow rate flowing from the first hydraulic pump 1 to the oil tank 3, and the oil tank 3 from the second hydraulic pump 2. And a second bypass valve 48 for controlling the flowing bypass flow rate. By implementing the present invention on the boom cylinder 6, stick cylinder 7, bucket cylinder 8, and swing motor 9 provided on the hydraulic excavator in this way, various operations by the hydraulic excavator can be performed efficiently and operability is improved. Can greatly contribute to the improvement of energy efficiency.

Needless to say, the present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, the high flow hydraulic actuator (boom cylinder 6, stick cylinder 7, attachment hydraulic actuator 10) includes Pressure oil is supplied from both the first and second hydraulic pumps 1 and 2, but the first and second hydraulic pumps 1, 1, In this case, the first and second flow control valves (the first boom flow control valve 25, the second boom flow control valve 29, the first The flow control valve 26 for one stick, the flow control valve 30 for the second stick, the flow control valve 28 for the first attachment, or the flow control valve 32 for the second attachment 32) is set to zero flow. May be controlled in so that, such control can be performed, for example, in the pump flow rate distribution calculation unit 72 of the controller 16.
Furthermore, in this embodiment, the case where the straight travel valve 11 is located at the first position X is described. However, when the straight travel valve 11 is located at the second position Y, the boom cylinder 6, the stick cylinder 7, the bucket cylinder 8, the swing motor 9, and the attachment hydraulic actuator 10 are supplied with pressure oil from the second hydraulic pump 2. In this case, each flow control valve (first The flow control valves 25 to 32) for the boom, the first stick, the bucket, the first attachment, the second boom, the second stick, the turning, and the second attachment are controlled by the control signal from the controller 16. Based on this, the supply flow rate from the second hydraulic pump 2 is controlled. In this case, the control units 74 to 78 for the boom, the stick, the bucket, the turning, and the attachment are command values for the flow control valves 25 to 32 based on the detection value of the second pump pressure sensor 56. Ask for.
In addition, the present invention is not limited to the hydraulic excavator, and can of course be applied to various work machines provided with the hydraulic actuator.

  The present invention can be used in a hydraulic actuator control circuit for performing oil supply / discharge control for a hydraulic actuator such as a hydraulic cylinder or a hydraulic motor.

DESCRIPTION OF SYMBOLS 1 1st hydraulic pump 2 2nd hydraulic pump 3 Oil tank 6 Boom cylinder 7 Stick cylinder 8 Bucket cylinder 9 Turning motor 10 Attachment hydraulic actuator 16 Controller 25, 29 First, 2nd boom flow control valve 26, 30 First Flow control valve for second stick 27 Flow control valve for bucket 28, 32 Flow control valve for attachment 31 Flow control valve for turning 33 Direction switching valve for boom 34 Direction switching valve for stick 35 Direction switching valve for bucket 36 Direction for turning Switching valve 37 Direction switching valve for attachment 47, 48 First and second bypass valves

Claims (5)

A hydraulic actuator control circuit for performing oil supply / discharge control for a hydraulic actuator, the hydraulic actuator control circuit including a first and second hydraulic pump and at least one of the first and second hydraulic pumps A plurality of hydraulic actuators supplied with pressure oil from, a flow control valve for controlling the supply flow rate from the first and second hydraulic pumps to each hydraulic actuator, and each hydraulic actuator disposed downstream of the flow control valve A direction switching valve that controls the discharge flow rate from each hydraulic actuator, but not the supply flow rate, and the bypass flow rate that flows from the first and second hydraulic pumps to the oil tank . one, a second bypass valve, while the flow control valve, Ru and control means for controlling the operation of the directional control valve and the bypass valve, before The hydraulic actuator includes a large flow hydraulic actuator supplied with pressure oil from both the first and second hydraulic pumps, and the flow control valve for the large flow hydraulic actuator is supplied from each of the first and second hydraulic pumps. The first and second flow rate control valves for controlling the supply flow rate, respectively, the supply flow rate from the first and second flow rate control valves are merged to flow to the direction switching valve, the control means, In controlling the flow control valve for each hydraulic actuator including the first and second flow control valves for the large flow hydraulic actuator, the discharge flow rate of the first and second hydraulic pumps is controlled by the operation amount of each hydraulic actuator operation tool. The distribution flow rate distributed according to the distribution flow rate, the flow rate supplied from the first and second hydraulic pumps to each hydraulic actuator calculated based on the distribution flow rate, and the pumps of the first and second hydraulic pumps A hydraulic actuator control circuit characterized in that to control the flow rate control valve for each hydraulic actuator based on the differential pressure between the load pressure of each hydraulic actuator.   2. The hydraulic actuator control circuit according to claim 1, wherein the flow control valve is an electromagnetic proportional poppet valve.   3. The hydraulic actuator control circuit according to claim 1, wherein the direction switching valve is a spool valve, and a discharge flow rate from the hydraulic actuator is controlled by a notch formed in the spool valve. According to any one of claims 1 to 3, the control means may calculates the discharge flow rate from the hydraulic actuator based on the operation amount for operating tool hydraulic actuator, the load pressure of the discharge flow rate and a hydraulic actuator that is the operational A hydraulic actuator control circuit that controls the direction switching valve based on the above. In any one of claims 1 to 4, a hydraulic actuator control circuit, a boom cylinder provided in the hydraulic excavator, the stick cylinder, bucket cylinder, a hydraulic actuator control for performing an oil supply and discharge control for the hydraulic actuator of the swing motor A hydraulic actuator control circuit for the bucket that controls the first and second hydraulic pumps and the supply flow rate from the first or second hydraulic pump to the bucket cylinder and the swing motor, Flow control valves for turning, flow control valves for the first boom and the first stick for controlling the supply flow from the first hydraulic pump to the boom cylinder and stick cylinder, respectively, and the boom hydraulic cylinder from the second hydraulic pump , Second boom for controlling the flow rate to the stick cylinder Each flow control valve for the clutch, and downstream of each of the flow control valves for the bucket and the swing, respectively, to switch the supply and discharge direction of the hydraulic oil to and from the bucket cylinder and the swing motor, and from the bucket cylinder and the swing motor Disposed on the downstream side of each direction switching valve for bucket and swing for controlling the discharge flow rate, and the flow control valve for the first and second booms, and switches the supply and discharge direction of hydraulic oil to the boom cylinder and from the boom cylinder The direction switching valve for the boom that controls the discharge flow of the oil and the flow control valve for the first and second sticks are arranged downstream, and the supply and discharge direction of the hydraulic oil to the stick cylinder is switched and the discharge flow from the stick cylinder is controlled. Direction control valve for the stick, and a first bypass that controls the bypass flow from the first hydraulic pump to the oil tank A hydraulic actuator control circuit characterized in that it comprises a valve, and a second bypass valve for controlling the bypass flow rate flowing into the oil tank from the second hydraulic pump.

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