WO2001036755A1

WO2001036755A1 - Control apparatus and control method for construction machine

Info

Publication number: WO2001036755A1
Application number: PCT/JP2000/007124
Authority: WO
Inventors: Kimimasa Onda
Original assignee: Shin Caterpillar Mitsubishi Ltd.
Priority date: 1999-11-18
Filing date: 2000-10-13
Publication date: 2001-05-25
Also published as: JP2001140285A; JP3612253B2

Abstract

A control apparatus of a construction machine which gives the operator an improved operating feel by enabling the operator to control the flow rate of a pump in accordance with the operator's preference and a load sense feel while suppressing a sharp increase of the operating speed of a hydraulic actuator and the hunting phenomenon induced thereby, a pump flow rate control means (3, 4) which controls the discharge of the hydraulic fluid from hydraulic pumps (51, 52) selects either a first control signal (F1-1(F1-2)) for controlling the discharge of the pump according to the characteristic that the discharge is in inverse proportion to the pressure of the hydraulic fluid in bypass passages (61b, 66c) on the downstream side of supply and exhaust control valves (57-60, 62-65) or a second control signal (F2-1(F2-2)) for controlling the discharge rate of the pump according to the characteristic that the discharge is in proportion to the manipulated varible of an operating member (54).

Description

Description Control device and control method for construction machinery

The present invention relates to a control device for a construction machine, which controls a discharge flow rate of hydraulic oil from a hydraulic pump to operate a working machine of a construction machine such as a hydraulic shovel, and a control method thereof. Background art

In general, a construction machine such as a hydraulic excavator includes an upper revolving unit 102, a lower traveling unit 100, and a work machine 118 as shown in FIG.

The undercarriage 100 has a right track 100R and a left track 100L that can be driven independently of each other, while the upper revolving structure 102 has a lower track 100 On the other hand, it is provided so as to be pivotable in a horizontal plane. For this reason, a traveling hydraulic motor (travel hydraulic actuator) as an independent power source is attached to each of the left track 100 L and the right track 100 R of the lower traveling body 100. The upper revolving unit 102 is provided with a hydraulic pressure motor for turning (a hydraulic hydraulic actuator for turning).

The working machine 118 mainly comprises a boom 103, a stick 104, a bucket 108, and the like, and the boom 103 rotates with respect to the upper rotating body 102. It is pivotally connected. A stick 104 is connected to the end of the boom 103 so as to be rotatable in the vertical plane.

A boom driving hydraulic cylinder (boom cylinder, boom driving hydraulic actuator) 105 for driving the boom 103 is provided between the upper swing body 102 and the boom 103. Along with the boom 1 0 A stick drive hydraulic cylinder (stick cylinder, stick drive hydraulic actuator) 106 for driving the stick 104 is provided between the stick 3 and the stick 104. Also, between the stick 104 and the bucket 108, a bucket driving hydraulic cylinder (bucket cylinder, baguette driving hydraulic actuator) 107 for driving the bucket 108 is provided. Is provided. Accordingly, the boom 103 is in the direction of arrow a and arrow b in FIG. 9, the stick 104 is in the direction of arrow c and arrow d in FIG. 9, and the bucket 108 is in the direction of arrow e and arrow in FIG. It is configured to be rotatable in the f direction.

The rotation of the boom 103 in the direction of arrow a in FIG. 9 is referred to as boom up. The rotation of the boom 103 in the direction of arrow b in FIG. 9 is referred to as boom down. The rotation of the stake 104 in the direction of arrow c in FIG. 9 is called stick-out, and the rotation of the stake 104 in the direction of arrow d in FIG. 9 is called stick-in. The rotation of the bucket 108 in the direction of arrow e in FIG. 9 is called bucket open, and the rotation of the bucket 108 in the direction of arrow f in FIG. 9 is called bucket-in.

As described later, in each of the cylinders 105 to 107 and the hydraulic motor, a hydraulic pump driven by an engine (mainly a diesel engine), a control valve for a boom, a control valve for a stick, A hydraulic circuit with multiple control valves such as a bucket control valve and a swirl control valve is connected. In addition, the operation room 101 of the upper revolving superstructure 102 has a left lever to control the operation of the excavator (running, turning, boom turning, stick turning, and baguette turning). A plurality of operating members such as a right lever, left pedal and right pedal are provided. Then, the moving amounts of the plurality of control valves are controlled in accordance with the operation of the operation member by the operator, whereby the cylinders 105 to 107 and the hydraulic motor are driven.

In this way, the cylinders 105 to 107 are driven to expand and contract, Various work such as excavation work is performed by driving the work machine 110, such as 103, stick 104, bucket 108, etc., or turning the upper swing body 102 by driving the swing motor. It has become.

Here, FIG. 10 is a diagram schematically showing a main part of a hydraulic circuit provided in a conventional hydraulic shovel.

As shown in FIG. 10, each of the hydraulic cylinders 105 to 107 and the hydraulic motors 109L, 109R, 110 includes a plurality of engines (mainly, a diesel engine) 500 (Here, two) Hydraulic pumps 510 and 520, and a hydraulic circuit 530 equipped with a plurality of control valves (supply and discharge control valves) 570 to 600 and 620 to 650 are connected.

When the operator operates the plurality of operation members 540, the movement amounts of the control valves 570 to 600 and 620 to 650 interposed in the hydraulic circuit 530 are controlled. Hydraulic oil from 520 is supplied at a predetermined pressure through a hydraulic circuit 530, and each hydraulic cylinder 105-: L07 or hydraulic motor 109L, 1 according to the supplied hydraulic pressure. 09 R, 110 are driven.

The plurality of operating members 540 include a boom operating member 540a that operates when rotating the boom 103 and a stick operating member 540a that operates when rotating the stick 104. b, a bucket operating member 540 c that is operated when rotating the bucket 108, and a swing operating member 540 d that is operated when rotating the upper revolving unit 102. And a traveling operation member 540e.

Here, the hydraulic pumps 510 and 520 discharge the hydraulic oil in the reservoir tank 700 as a predetermined oil pressure. Here, a swash plate rotary piston pump (piston type variable displacement pump, variable discharge amount type piston) is used. Pump) and It is configured. These hydraulic pumps 510 and 520 can adjust the pump discharge flow rate by changing the stroke amount of a piston (not shown) provided in the hydraulic pump. That is, in these hydraulic pumps 5110, 520, one end of the piston is configured to abut against a swash plate (creep plate: not shown), and is discharged from the hydraulic pumps 5110,520. By guiding the hydraulic oil and hydraulic oil downstream of each control valve 570-600, 620-650, and changing the inclination (tilt angle) of the swash plate of the hydraulic pumps 510, 520, The pump discharge flow rate can be adjusted by changing the stroke of the piston.

As shown in FIG. 10, the hydraulic circuit 530 includes a first circuit unit 550 and a second circuit unit 560.

The first circuit section 550 includes an oil passage 610 connected to the first hydraulic pump 510, and a right traveling motor interposed in the oil passage 610 for controlling supply and discharge of hydraulic oil. And a supply / discharge control valve such as a control valve 570, a packet control valve 580, a first boom control valve 590, and a second stick control valve 600.

Then, the hydraulic oil from the first hydraulic pump 5110 is supplied to the right running motor 1109R via the oil passage 6110, the right running motor control valve 570, and the right running motor It is designed to drive 109 R. Hydraulic oil from the first hydraulic pump 5110 is supplied to the bucket driving hydraulic cylinder 107 through the oil passage 610 and the baguette control valve 580, and the oil passage 610, This is supplied to the boom drive hydraulic cylinder 105 via the 1 boom control valve 590, and further supplied to the stick drive hydraulic cylinder 106 via the oil passage 610 and the second stick control valve 600. Thus, the cylinders 105, 106, and 107 are driven.

Also, a throttle 8110 is provided downstream of the oil passage 6110b of the first circuit section 550. When the control valve 570 to 600 is in the neutral or intermediate movement position, the bypass flow rate returns the hydraulic oil from the first hydraulic pump 510 to the reservoir tank 750 through this throttle 810. It is like that. Further, the hydraulic oil upstream (control valve side) of the throttle 810 is guided to the hydraulic pump 510, and the pressure of the hydraulic oil causes the tilt angle of the hydraulic pump 510 to decrease. It is controlled.

The second circuit unit 560 includes an oil passage 660 connected to the second hydraulic pump 520, and a left running motor interposed in the oil passage 660 for controlling supply and discharge of hydraulic oil. It is provided with a supply / discharge control valve such as a control valve 62, a turning motor control valve 63 0, a first stick control valve 64 0, and a second boom control valve 65 0. Then, the hydraulic oil from the second hydraulic pump 520 is supplied to the left traveling motor 109 L via the oil passage 660 and the left traveling motor control valve 620, whereby the left traveling motor One night, 109 L is driven. The hydraulic oil from the second hydraulic pump 520 is supplied to the slewing motor 110 via the oil passage 660 and the slewing motor control valve 630, whereby the slewing motor 1 10 is driven. Further, the hydraulic oil from the second hydraulic pump 520 is supplied to the stick driving hydraulic cylinder 106 via the oil passage 660 and the first stick control valve 640, and the oil passage 6 60, and is supplied to a boom drive hydraulic cylinder 105 via a second boom control valve 650, whereby the respective cylinders 105, 106 are driven.

In addition, a throttle 8200 is provided downstream of the oil passage 660c of the second circuit section 560, and the bypass flow rate at the neutral or intermediate movement position of the control valves 62 to 65 is The hydraulic oil from the second hydraulic pump 520 is returned to the reservoir tank 700 through the throttle 8200. Further, the hydraulic oil on the upstream side (control valve side) of the throttle 8200 is guided to the hydraulic pump 5200. The tilt angle of the hydraulic pump 520 is controlled by the pressure of the hydraulic oil.

In addition, the second hydraulic pressure of the second circuit section 560 is set so that sufficient hydraulic oil can be supplied to the stick 104 important for construction machine operation even when operating simultaneously with another work machine 118. In addition to the hydraulic oil from the pump 520, the hydraulic oil from the first hydraulic pump 510 in the first circuit section 550 is also supplied to the stick driving hydraulic cylinder 106. .

Therefore, the first stick control valve 640 is interposed in the oil passage 660 of the second circuit unit 560, and the control for the second stick is provided in the oil passage 610 of the first circuit unit 550. Valve 600 is interposed. The moving amount of the first stick control valve 640 is controlled according to the operating amount of the stick operating member 540b, and the moving amount of the second stick control valve 600 is controlled by the stick operating member. By controlling in accordance with the operation amount of 540b, supply and discharge of hydraulic oil to and from the hydraulic cylinder 106 for driving the stick can be performed. Similarly, during the simultaneous operation with the other work implements 118, the first hydraulic pump 5110 of the first circuit section 550 is operated so that sufficient hydraulic oil is supplied to the boom 103. In addition to the hydraulic oil, hydraulic oil from the second hydraulic pump 520 of the second circuit section 560 is also supplied to the boom driving hydraulic cylinder 105.

For this reason, the first boom control valve 5 9

0 is interposed, and a second boom control valve 65 is interposed in an oil passage 660 of the second circuit portion 560. The amount of movement of the first boom control valve 590 is controlled in accordance with the amount of operation of the boom operating member 540a, and the amount of movement of the second boom control valve 650 is controlled for the boom. By controlling the operation member 540a in accordance with the operation amount, the supply and discharge of the hydraulic oil to and from the boom drive hydraulic cylinder 105 can be performed. . A pilot pump and a proportional pressure reducing valve (not shown) are used to control the moving amounts of the control valves 570 to 600 and 620 to 650 in accordance with the operating amounts of the operating members 540. A pilot hydraulic circuit equipped with a pilot pressure circuit is also provided, and the pilot oil pressure from the pilot pump is applied to each control valve 570 to 600, 620 to 650 as a predetermined pressure by a proportional pressure reducing valve. It is like that.

By the way, each of the control valves 570 to 600 and 620 to 600 is configured as a spool valve, and each of them is configured with a plurality (here, five) of throttles.

For example, as shown in FIG. 11, the swing motor control valve 63 0 is provided with an oil passage (operating oil supply passage, P—C) that communicates the second hydraulic pump 52 0 and the swing motor 110. Passage) An oil passage (operating oil discharge passage) that connects the PC throttle 40, which is interposed in the 660, 660a, and 970, with the rotation motor 110 and the reservoir tank 700 , C—T passage) A bypass oil passage (bypass passage) that communicates the C—T throttle 41 interposed in the 960, 660 b with the second hydraulic pump 520 and the reservoir tank 700 ) 660, 660c, and a bypass passage restrictor 42 interposed therebetween. The hydraulic oil supply passage and the hydraulic oil discharge passage constitute a hydraulic oil supply and discharge passage.

The opening area of the oil passages 660, 660a, 970 that communicates the second hydraulic pump 520 and the rotating motor 110 by the PC throttle 40 is provided. And the PC opening area (PC)] are adjusted. In addition, the opening area of the oil passages 960, 660b communicating the turning motor 110 and the reservoir tank 700 by the C-T throttle 41 [the opening area of the hydraulic oil discharge passage, C-T opening area (CT)] is adjusted. Further, the opening area of the oil passages 660 and 660 c that communicates the second hydraulic pump 520 and the reservoir tank 700 by the bypass passage restrictor 42 [the opening area of the bypass passage, the opening area of the bypass passage] (C)] is adjusted. In FIG. 11, the turning motor control valve 630 is located at the left turning side position, but the turning motor control valve 630 is operated by the operating amount of the turning motor operating member 540d. In accordance with the [operating member operation amount (A)], it is moved upward in Fig. 11 to turn the bypass passage throttle 42 of the turning motor control valve 63 0 into the bypass passage 66 0, 66 0 By adjusting the amount of movement of the control valve 630 for the swing motor by interposing c, the control valve 630 for the swing motor can be set to the neutral position by adjusting the control valve travel amount (B). it can. In addition, the turning motor control valve 630 is moved to the uppermost position in FIG. 11 according to the operation amount of the turning motor operation member 5400d [operation member operation amount (A)]. The P_C throttle 40 of the swing motor control valve 63 0 is interposed in the P-C passages 66 0, 66 0 a, 97 0 and the swing motor control valve 63 0 C — By interposing the T throttle 41 in the C — T passages 960, 660b, by adjusting the amount of movement of the swing motor control valve 630 (the amount of control valve movement (B)), The turning mode control valve 63 0 can be set to the right turning side position. When the turning motor control valve 630 is located between the left turning position and the neutral position or between the neutral position and the right turning position, it is said to be at the intermediate moving position.

Although the hydraulic circuit for driving the swing motor 110 has been described here as an example, other hydraulic actuators 105 to 107, 10 0, such as a hydraulic cylinder for driving a stick, are used. The hydraulic circuit for driving 9 R and 109 L is configured similarly.

In this way, a hydraulic circuit for driving each hydraulic actuator 105-: L07, 109R, 109L, 110 is constructed. The pump flow control (pump tilt angle control) is performed as follows in order to operate the turning motor 110 included in. When the operating member 540 d for the turning motor is operated by the operator and the operation amount (A) is AO, the operating member operation as shown in Fig. 12 (a) is performed. Based on the characteristic indicating the relationship between the amount (A) and the control valve movement amount (B), the movement amount (B) of the turning motor control valve 630 as the supply / discharge control valve is set to B0. Next, the relationship between the control valve movement amount (B) and the bypass passage opening area (C) as shown in FIG. 12B is shown according to the movement amount B 0 of the swing motor control valve 630. Based on the characteristics, the bypass passage opening area (C) of the swing motor control valve 630 becomes CO. In this case, the C-T opening area (CT) of the turning motor control valve 630 is CT0, and the PC opening area (PC) is PC0.

Then, when the load pressure is constant, based on the characteristic indicating the relationship between the bypass passage opening area (C) and the bypass flow rate (D) as shown in Fig. 12 (c), According to the bypass passage opening area C 0 of the control valve 630, the flow rate (bypass flow rate) (D) of the hydraulic oil flowing through the bypass passage of the swing motor control valve 630 becomes DO.

As a result, based on the characteristic indicating the relationship between the bypass flow rate (D) and the hydraulic oil pressure (E) guided to the hydraulic pump 520 as shown in FIG. The pressure (E) of the hydraulic oil guided to the hydraulic pump 520 becomes E0, and the pressure (E) of the hydraulic oil guided to the hydraulic pump 520 and the pump flow (pump tilt) as shown in Fig. 12 (e) Angle) (F), the pump tilt angle (pump flow rate) of the hydraulic pump 520 (F) becomes F 0 according to the pressure E 0 of the hydraulic oil guided to the hydraulic pump 520, Is done.

Here, the case where only the swing motor 110 is operated is described. However, when the other hydraulic actuators 105 to 107, 109R, and 109L are also operated at the same time. In order to control the pump tilt angle of the hydraulic pumps 510, 520, the hydraulic oil is guided to the bypass passage downstream of each supply / discharge control valve (upstream of the throttles 810, 820). Because To determine the path flow rate, bypass each supply / discharge control valve that controls the supply / discharge of hydraulic oil to / from each hydraulic function 105-107, 109R, 109L, 110 The smallest opening area of the passage opening area is used.

By the way, in the hydraulic circuit 530 configured as described above, as shown in FIG. 10, each of the control valves 5 70 to 600 and 620 to 650 that operate according to the operation amount of each of the operation members 540 is bypassed. A bypass passage between the control valves 600, 650 and the tank 700, which is arranged in series with the oil passages 6 10, 6 10 b, 660, 660 c constituting the passage, and which is arranged at the most downstream side thereof. The oil passages 6 10 b and 660 c (the oil passages upstream of the throttles 8 10 and 820) and the hydraulic pumps 5 10 and 5 20 are connected. Then, the pump tilt angle (pump flow rate) of the hydraulic pumps 510, 520 is controlled based on the pressure of the hydraulic oil guided from the oil passages 610b, 660c constituting the bypass passage. (This type of control is called negative flow control).

For example, when a plurality of operating members 540 are operated simultaneously, and each hydraulic actuator 105-5, 107, 109 R, 109 L, 110 is operated simultaneously, the downstream of each supply / discharge control valve Hydraulic oil flowing through the bypass passages 660 and 660c on the side is guided to the hydraulic pumps 5110 and 520, so that the pump discharge flow rate of the hydraulic pumps 510 and 520 supplies hydraulic oil through each supply / discharge control valve. Of the hydraulic pumps 510, 520 so that the sum of the required flow rates of 105 to 107, 109R, 109L, 110 is obtained. (Pump flow rate) is controlled.

However, in such a conventional control device for construction machinery, the influence of the load fluctuation acting on the hydraulic actuators 105-107, 109R, 109L, 110 is affected by the fluctuation of the bypass flow rate. And the hydraulic pumps 5 10 and 6 1 based on the bypass flow rate fluctuated by the load fluctuation in this way. Since the pump tilt angle control of 0 is performed, this may lead to a change in the pump discharge flow rate, which may cause a sudden change in the operating speed of the hydraulic actuator.

Here, assuming that the operation amount (A) of the turning motor evening operation member 540 d is constant at the intermediate operation amount, the corresponding moving amount (B) of the turning motor evening control valve 63 0 also becomes It becomes constant at the intermediate position, and the PC opening area (PC) throttled by the PC throttle 40, which is interposed in the oil passage connecting the hydraulic pump 520 and the swing motor 110, also becomes constant. The bypass opening area (C) narrowed by the bypass passage throttle 42 interposed in the oil passage communicating the hydraulic pump 520 and the tank 700 is also constant. In such a hydraulic circuit state, the P_C throttle 40 and the bypass passage throttle 42 have a constant opening degree [that is, the P-C opening area (PC) and the bypass opening area (C) are constant. The hydraulic pump 520 is discharged because the hydraulic pump 520 and the swing motor 110 are connected to each other, and the hydraulic pump 520 and the tank 700 are connected to each other. Hydraulic oil is diverted to the rotating motor 110 side and the tank 700 side.

In such a hydraulic circuit state, for example, when the work machine 118 expands and contracts during turning and the load W acting on the turning motor 110 fluctuates, the turning motor 110 is operated. The operating pressure of the oil pump fluctuates, and an oil passage (PC passage) that connects the hydraulic pump 520 and the swing motor 110 and an oil passage that connects the hydraulic pump 520 and the tank 700 ( Since the pressure balance with the bypass passage fluctuates, the bypass flow rate (D) also fluctuates. As a result, the pressure (E) of the hydraulic oil guided to the hydraulic pump 520 also fluctuates, and the pump flow rate (pump tilt angle) (F) controlled by the pressure (E) of the hydraulic oil also fluctuates. As a result, the operating speed of the swing motor 110 may suddenly change. For example, when the load W suddenly decreases, the operating pressure of the swing motor 110 as a hydraulic actuator decreases, and the flow rate to the swing motor 110 increases, so that the bypass flow rate (D ) Decreases from D 0 to D 1.

When the bypass flow rate (D) decreases from D 0 to D 1 in this manner, as shown in FIG. 13 (a), which shows the relationship between the bypass flow rate and the pressure of the hydraulic oil guided to the hydraulic pump, the hydraulic pump Hydraulic oil pressure (E) directed to 520 decreases from E 0 to E 1.

Then, when the pressure (E) of the hydraulic oil guided to the hydraulic pump 520 decreases from E0 to E1, the pump flow rate (pump tilt angle) is controlled to increase, and the hydraulic pump shown in FIG. The pump flow rate (F) increases from F 0 to F 1 as shown in the diagram showing the relationship between the guided hydraulic oil pressure and the pump flow rate.

When the pump flow rate increases in this way, the supply flow rate of hydraulic oil to the swing motor 110 further increases, and as a result, the operating speed of the swing motor 110 may increase sharply. There is.

Here, the turning motor 110 has been described as an example, but the same applies to other hydraulic actuators 105-107, 109R, 109L.

Thus, as shown in Fig. 13 (c), the decrease in load W acts to increase the pump flow rate, and the hydraulic actuators 105-107, 109R, 109L It is not preferable to increase the operating speed of 110, contrary to the intention of the operator. In Fig. 13 (c), the speed of pumping (pump flow rate) F0 is the expected speed according to the amount of operation of the operating member 54, and the initial balance point is set at the expected speed of pumping. This is the balance between the actuyue and the load when moving.

For example, the operator reduces the operation amount of the operation member 540 in order to set the operation speed of the work machine (hydraulic actuator) to a low speed or an intermediate speed. Even though the intermediate operation amount is fixed at AO, the operating speed of the work equipment 1 18 suddenly increases, so the operator's intended operation cannot be performed, which is preferable in terms of operability. In addition, a sudden change in the operating speed of the work equipment is extremely inconvenient in terms of safety.

In particular, such a decrease in the load W causes, for example, a sudden increase in the turning speed (swing jumping) in a turning operation and a hunting phenomenon of the turning speed resulting therefrom, thereby deteriorating the turning operation. Become. For example, when the boom-up fine operation and the stick-out fine operation are performed simultaneously to lift the suspended load suspended at the tip of the stick 104, the stick 104 rotates in the direction d in FIG. As the load is applied, the load action point approaches the center of rotation, so that the load acting on the boom cylinder 105 and the stick cylinder 106 decreases. As described above, the reduction in the load on the boom cylinder 105 and the stick cylinder 106 acts to increase the pump flow rate. This will increase the working speed rapidly, which may result in reduced hunting.

On the other hand, when the load W increases, the operating pressure of the swing motor 110 increases, and the flow rate to the swing motor 110 decreases, so the bypass flow rate (D) increases from D 0 to D 2 accordingly. I do. When the bypass flow rate (D) increases from DO to D2, the pressure (E) of the hydraulic oil guided to the hydraulic pump 520 changes from E0 to E2 as shown in FIG. 13 (a). To increase. Then, when the pressure (E) of the hydraulic oil guided to the hydraulic pump 520 increases from E0 to E2, the pump flow rate (pump tilt angle) (F) is controlled in the decreasing direction, and FIG. As shown in b), the pump flow rate (F) decreases from F0 to F2. Such a decrease in the pump flow rate (F) further reduces the flow rate of the hydraulic oil supplied to the turning motor 110, and as a result, the operating speed of the turning motor 110 may be reduced.

Here, the turning mode 110 has been described as an example, but the same applies to other hydraulic factories.

As shown in Fig. 13 (c), the increase in the load W acts to decrease the pump flow rate and decrease the operating speed of the hydraulic actuator.

Such a decrease in the operating speed of the hydraulic actuator has advantages and disadvantages in the operability of the work machine 118.

Advantageously, for example, the magnitude of the load W

—This is the point where the evening can be sensed (load-sensitive feeling). That is, for example, when excavation work is performed by performing a stick-in operation with the operation member 540 as the intermediate operation amount A0, if the resistance increases due to contact with an underground object (for example, a pipe or the like), As described above, this acts to reduce the pump flow rate, thereby reducing stick-in speed. Thus, there is an advantageous aspect that the operator can interrupt or correct the stick-in operation by sensing the change in the stick-in speed.

Therefore, the operating speed is reduced in the operation area where the operation amount of the operation member 540 is relatively large in the hydraulic actuator that drives the work machine 118 used for excavation work such as stick-in packet-in. The properties are favorable.

On the other hand, the disadvantage is that the work speed is reduced in hanging work performed at a low speed. For example, the fine operation of the boom up and the fine operation of the stick When the operation of lifting the suspended load is performed, the load application point moves away as the stick 104 rotates in the direction C in Fig. 9, so that the load acts on the boom cylinder 105 and the stick cylinder 106. This increases the load on the system.

Such an increase in the load on the boom cylinder 105 and the stick cylinder 106 acts to reduce the pump flow rate as described above, so that the work of the boom cylinder 105 and the stick cylinder 105 is performed. The speed will be reduced, and the operation of the boom 103 as a working machine will stop depending on the working conditions (ie, the amount of operation and the amount of load) during the lifting operation. There is a risk that it will.

For this reason, in the hydraulic actuator that drives the work equipment 118 used for hanging work such as boom-up sticks, etc., the pump flow rate decreases in the operation range where the operation amount of the operation member is relatively small. Is not good and needs improvement.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has an advantage in that a pump flow rate can be controlled in accordance with an operator's preference to improve a driving feeling. In addition to suppressing the sudden increase in the operating speed of the hydraulic pump and the hunting phenomenon induced by this, the operating speed of the hydraulic actuator due to the load fluctuation in the fine operation range while ensuring the load-responsive feeling accompanying the increased load It is an object of the present invention to provide a control device for a construction machine and a control method for the same, which can suppress the change of the construction and improve the operability thereof. Disclosure of the invention

A control device for a construction machine according to the present invention includes: an operating member that is operated by an operator to output an electric signal; a hydraulic pump that discharges hydraulic oil in a tank; A hydraulic actuator driven by hydraulic oil discharged by a hydraulic pump, a hydraulic oil supply passage for supplying hydraulic oil to the hydraulic actuator, and a hydraulic oil supply passage interposed between the hydraulic oil supply passage and operation to the hydraulic actuator An operation from a hydraulic pump in a control device for a construction machine having a control valve for controlling oil supply and a bypass passage for returning hydraulic oil not supplied to the hydraulic actuator to the tank via the control valve. Pump flow control means for controlling a discharge flow rate of the oil, the pump flow control means including a first control signal and a first control signal for controlling the pump flow rate based on a characteristic substantially inversely proportional to the flow rate of the hydraulic oil in the bypass passage. And selecting one of the second control signals for controlling the pump flow rate based on a characteristic that is substantially directly proportional to the operation amount of the operating member and the hydraulic oil from the hydraulic pump. It is characterized by being configured to control the output flow rate.

Accordingly, the pump flow rate control means controls the pump flow rate based on a characteristic substantially inversely proportional to the flow rate of the hydraulic oil downstream of the supply / discharge control valve of the hydraulic oil supply / discharge passage, and the first control signal and the operation signal. A configuration in which one of the second control signals for controlling the pump flow rate is controlled based on a characteristic that is substantially directly proportional to the operation amount of the member, and the discharge flow rate of the hydraulic oil from the hydraulic pump is controlled. Therefore, the positive flow control and the negative flow control can be selectively used according to the operator's preference, and there is an advantage that the driving feeling can be improved. In addition, for example, when the operator intends to perform work at a certain work machine speed, or in a lifting operation, the operating speed of the hydraulic actuator increases rapidly due to a decrease in the load applied to the hydraulic actuator, While it is possible to suppress the occurrence of the hunting phenomenon caused by this, it is possible to reduce the operating speed of the hydraulic actuator, for example, in excavation work with an increase in the load applied to the hydraulic actuator. Load sensitive There is an advantage that ealing can be secured.

Preferably, the pump flow rate control means is configured to control a discharge flow rate of the hydraulic oil from the hydraulic pump by selecting a control signal for decreasing the pump flow rate from the first control signal and the second control signal.

Accordingly, the pump flow control means selects a control signal for decreasing the pump flow rate from the first control signal and the second control signal to control the discharge flow rate of the hydraulic oil from the hydraulic pump. The load applied to the hydraulic actuator fluctuates depending on the work such as lifting and lifting work.The pump flow control based on the first control signal and the pump flow control based on the second control signal vary depending on the load fluctuation. There is an advantage that can be automatically switched. In addition, since the first control signal is compared with the second control signal and a control signal that reduces the pump flow rate is selected from the first control signals, control switching can be performed with a simple configuration. There are advantages too.

Further, it is preferable that the pump flow control means is configured to select the second control signal when the second control signal is smaller than a predetermined value and control the discharge flow rate of the hydraulic oil from the hydraulic pump.

Accordingly, when the second control signal is smaller than the predetermined value, the pump flow rate control means selects the second control signal to control the discharge flow rate of the hydraulic oil from the hydraulic pump. There is an advantage in that a change in the operating speed of the hydraulic actuator due to a load change in a fine operation range where a fine operation is performed can be suppressed.

Further, when the second control signal is larger than a predetermined value, the pump flow control means selects a control signal for reducing the pump flow rate from the first control signal and the second control signal, When the control signal is equal to or less than a predetermined value, it is preferable to select the second control signal and control the discharge flow rate of the hydraulic oil from the hydraulic pump. Thus, when the second control signal is larger than the predetermined value, the pump flow rate control means selects the control signal for decreasing the pump flow rate from the first control signal and the second control signal, When the control signal is less than a predetermined value, the second control signal is selected.If the operator is not in the fine operation range where the operation member is finely operated, the load applied to the hydraulic actuator may be reduced. As a result, it is possible to suppress a sudden increase in the operating speed of the hydraulic actuator and to prevent the hunting phenomenon from being caused by this, and to suppress an increase in the load applied to the hydraulic actuator and the hydraulic actuator. While the load-responsive feeling can be ensured by reducing the operating speed of the night, the hydraulic pressure due to load fluctuations in the fine operation area where the operator finely operates the operating members There is an advantage that a change in the operating speed of Kuchiyue Isseki can suppress.

Also, the construction machine control method of the present invention includes an operation member that is operated by an operator to output an electric signal, a hydraulic pump that discharges hydraulic oil in a tank, and a hydraulic pump that is driven by hydraulic oil discharged by a hydraulic pump. A hydraulic oil supply, a hydraulic oil supply passage for supplying hydraulic oil to the hydraulic oil supply, a control valve interposed in the hydraulic oil supply passage, and controlling the supply of hydraulic oil to the hydraulic oil supply. A control method for a construction machine, comprising: a bypass passage for returning hydraulic oil, which is not supplied to the hydraulic actuator through a control valve, to the tank, wherein a flow rate of the hydraulic oil in the bypass passage is detected. A first control signal setting step for setting a first control signal for controlling the pump flow rate based on a characteristic substantially inversely proportional to the flow rate of the operation section; detecting an electric signal from the operation member; A second control signal setting step for setting a second control signal for controlling the pump flow rate based on a characteristic that is substantially directly proportional to the manipulated variable of the first control signal, and a first control set in the first control signal setting step Signal and the second control signal set in the second control signal setting step. A pump flow control step of selecting a control signal to control a discharge flow rate of hydraulic oil from the hydraulic pump.

As a result, the first control signal for controlling the pump flow rate and the operation amount of the operation member for controlling the pump flow rate based on the characteristic substantially inversely proportional to the flow rate of the hydraulic oil downstream of the supply / discharge control valve of the hydraulic oil supply / discharge passage are provided. Since either one of the second control signals for controlling the pump flow rate is controlled based on the approximately proportional characteristic and the discharge flow rate of the hydraulic oil from the hydraulic pump is controlled, Accordingly, positive flow control and negative flow control can be used properly, and there is an advantage that driving feeling can be improved. In addition, for example, when the operator attempts to work at a certain speed of the work equipment, or in the case of lifting work, the operating speed of the hydraulic actuator increases rapidly due to the decrease in the load applied to the hydraulic actuator. While it is possible to suppress the occurrence of the hunting phenomenon due to the induction, it is possible to suppress the load-responsive feeling by reducing the operating speed of the hydraulic actuator along with the increase in the load applied to the hydraulic actuator during excavation work, for example. There is an advantage that a ring can be secured.

Preferably, in the pump flow rate control step, a control signal for reducing the pump flow rate is selected from the first control signal and the second control signal. Thereby, the first control signal and the second control signal Of these, the control signal to reduce the pump flow rate is selected to control the discharge flow rate of hydraulic oil from the hydraulic pump, so that the load applied to the hydraulic Although it fluctuates, there is an advantage that the pump flow control by the first control signal and the pump flow control by the second control signal can be automatically switched according to the fluctuation of the load. In addition, the first control signal is compared with the second control signal, and the pump flow of the first control signal is compared with the first control signal. There is also an advantage that control switching can be performed with a simple configuration because a control signal that reduces the amount is selected.

Further, in the pump flow rate control step, it is preferable that the second control signal is selected when the second control signal is smaller than a predetermined value.

With this, in the pump flow rate control step, when the second control signal is smaller than the predetermined value, the second control signal is selected to control the discharge flow rate of the hydraulic oil from the hydraulic pump, so that the operator operates There is an advantage that it is possible to suppress a change in the operating speed of the hydraulic actuator due to a load change in a fine operation range in which a member is finely operated.

Further, in the pump flow rate control step, when the second control signal is larger than a predetermined value, a control signal for reducing the pump flow rate is selected from the first control signal and the second control signal, while the second control signal is selected. When the control signal is equal to or less than a predetermined value, it is preferable that the second control signal is selected.

With this, in the pump flow rate control step, when the second control signal is larger than the predetermined value, the control signal for decreasing the pump flow rate is selected from the first control signal and the second control signal, while the second control signal is selected. If the control signal is smaller than the predetermined value, the second control signal is selected to control the discharge flow rate of the hydraulic oil from the hydraulic pump. As the load on the hydraulic actuator decreases, it is possible to prevent the operating speed of the hydraulic actuator from increasing rapidly in the evening, and to suppress the occurrence of a hunting phenomenon due to this, and to reduce the load on the hydraulic actuator. As the load increases, the operating speed of the hydraulic actuator can be reduced to ensure a load-responsive feeling, while the operator makes fine adjustments to the operating members. There is an advantage that a change in the operating speed of the hydraulic actuator due to a load change in a fine operation range can be suppressed. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a control block diagram for explaining pump tilt angle control in a control device and a control method for a construction machine according to an embodiment of the present invention.

FIG. 2 is an overall configuration diagram of a control device for a construction machine according to an embodiment of the present invention.

FIG. 3 is a schematic diagram for explaining a control valve of the control device for a construction machine according to one embodiment of the present invention.

FIG. 4 is a block diagram for explaining setting of a pump tilt angle corresponding to a bypass pressure in the control device and the control method for a construction machine according to one embodiment of the present invention.

FIG. 5 is a block diagram for explaining the setting of the pump tilt angle corresponding to the operation member in the control device and the control method for the construction machine according to one embodiment of the present invention.

FIG. 6 is a block diagram for explaining setting of a pump tilt angle corresponding to speed control in the control device and the control method for a construction machine according to one embodiment of the present invention.

FIGS. 7 (a) to 7 (d) show the load W and the working machine speed (pump) when the pump tilt angle corresponding to the speed control is set in the control device and the control method of the construction machine according to the embodiment of the present invention. Fig. 7 (a) is a diagram showing the relationship with the tilt angle. Fig. 7 (a) shows the case where the pump tilt angle is controlled based on the characteristic inversely proportional to the bypass flow rate. When the pump tilt angle control is performed based on the characteristic proportional to the pump flow, Fig. 7 (c) shows the pump tilt angle selectively using the characteristic inversely proportional to the bypass flow rate and the characteristic proportional to the operation member operation amount. Fig. 7 (d) shows the case where the pump tilt angle control is performed based on the required tilt angle that is smaller than the predetermined value. I have.

FIG. 8 is a block diagram for explaining the setting of the pump tilt angle corresponding to the allowable horsepower in the control device and the control method for the construction machine according to the embodiment of the present invention.

FIG. 9 is a schematic perspective view showing a general construction machine.

FIG. 10 shows an overall configuration diagram of a conventional control device for construction machines.

FIG. 11 is a schematic diagram for explaining pump tilt angle control in a conventional construction machine control device.

Figs. 12 (a) to 12 (e) are diagrams for explaining pump tilt angle control in a conventional control device for construction machinery, and Fig. 12 (a) is a diagram illustrating operation member operation amount and control valve movement. Fig. 12 (b) shows the relationship between the control valve travel and the control valve opening area, and Fig. 12 (c) shows the relationship between the bypass oil passage opening area and the bypass flow rate. Fig. 12 (d) shows the relationship between the bypass flow rate and the output signal of the bypass pressure detecting means. Fig. 12 (e) shows the output signal of the bypass pressure detecting means and the pump flow rate (pump tilt). The figure shows the relationship with the angle of rotation.

Figs. 13 (a) to 13 (c) are diagrams for explaining the problem of pump tilt angle control in a conventional control device for construction machinery. Fig. 13 (a) shows bypass flow rate and bypass pressure. Figure 13 (b) shows the relationship between the output signal of the detection means and the output signal of the bypass pressure detection means and the pump flow rate (pump tilt angle). Figure 13 (c) shows the load. The figure which shows the relationship between W and the speed (pump flow rate) of akuchiyue is shown respectively. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, a construction machine according to the present embodiment will be described. This construction machine is a construction machine (working machine) such as a hydraulic shovel, as described in the prior art (see Fig. 9), and works with the upper revolving unit 102 and the lower traveling unit 100. Machine 1 1 8

The undercarriage 100 has a right track 10OR and a left track 100L that can be driven independently of each other, while the upper revolving structure 102 has It is provided so that it can turn in a horizontal plane. The work machine 118 mainly includes a boom 103, a stick 104, a bucket 108, and the like, and the boom 103 rotates with respect to the upper rotating body 102. It is pivotally connected. A stick 104 is connected to the end of the boom 103 so as to be rotatable in the vertical plane.

A boom drive hydraulic cylinder (boom cylinder, boom drive hydraulic actuator) 105 for driving the boom 103 is provided between the upper swing body 102 and the boom 103. In addition, between the boom 103 and the stick 104, a stick driving hydraulic cylinder (stick cylinder, stick driving hydraulic actuator) 106 for driving the stick 104 is provided. Have been. Further, between the stick 104 and the bucket 108, there is a bucket driving hydraulic cylinder (a bucket cylinder, a packet driving hydraulic actuator) for driving the bucket 108. 7 are provided.

With such a configuration, the boom 103 is in the directions a and b in the figure, the stick 104 is in the directions c and d in the figure, and the knocket 108 is the direction e and f in the figure. It is configured to be rotatable.

Here, FIG. 2 is a diagram schematically showing a main part of a hydraulic circuit of such a hydraulic shovel.

As shown in FIG. 2, the left track 100 L and the right track 100

R is a running motor as an independent power source. R is provided, and the upper swing body 102 is provided with a swing motor 110 for swingably driving the upper swing body 102 with respect to the lower traveling body 100.

These traveling motors 110 L and 109 R and turning motors 110 are configured as hydraulic motors that are operated by hydraulic pressure. As described later, engines (mainly diesel engines) are used. Hydraulic oil from a plurality (here, two) of hydraulic pumps 51, 52 driven by 50 is supplied at a predetermined pressure via a hydraulic circuit 53, and the operation supplied in this manner is performed. Each hydraulic motor 109 L, 109 R, 110 is driven according to the hydraulic pressure.

Here, the hydraulic pumps 51 and 52 discharge the hydraulic oil in the reservoir tank 70 as a predetermined oil pressure. Here, a swash plate rotary piston pump (piston type variable displacement pump, variable discharge amount type piston) is used. Pump). These hydraulic pumps 51 and 52 can adjust the pump discharge flow rate by changing the stroke amount of a piston (not shown) provided in the hydraulic pump.

That is, in these hydraulic pumps 51 and 52, one end of the piston is configured to contact a swash plate (creep plate: not shown), and the inclination (tilt angle) of the swash plate will be described later. The pump discharge flow rate can be adjusted by changing the piston stroke by changing it based on the operation signal from the controller 1.

As described above, the inclination of the swash plate can be changed based on the operation signal from the controller 1. In addition to the pressure of the hydraulic oil in the oil passages constituting the hydraulic circuit, each operation member 5 by the operator is changed. Since the amount of operation in 4 can be taken into account, it is possible to improve the driving feeling during operation compared to the conventional method in which the pressure of the hydraulic oil in the oil passage is guided to change the inclination of the swash plate. Can be done.

The engine 50 is designed so that the operator can set the engine speed by switching the engine speed setting dial. Here, the maximum engine speed (for example, about 200 rpm) and the minimum engine speed are set. The number (for example, about 100 rpm) can be switched in multiple stages. Note that the engine speed is not limited to such a stepwise switching, but may be a type that can be changed smoothly. Further, the total horsepower of the engine 50 is consumed for driving these hydraulic pumps 51 and 52 and a pilot pump 83 described later.

In addition, for each cylinder 105 to 107,

As with 09 L, 109 R and turning motor 110, the hydraulic pressure of hydraulic oil supplied from multiple (here, two) hydraulic pumps 51, 52 driven by engine 50 Driven by the

The operation room 101 also has a left lever, a right lever, a left pedal, and a right pedal for controlling the operation of the hydraulic excavator (running, turning, boom turning, stick turning, and bucket turning). A plurality of operation members 54 such as pedals are provided. These operation members 54 are configured as electric operation members (for example, electric operation levers), and output an electric signal corresponding to the operation amount to a controller (control means) 1 described later.

Further, a plurality of work mode switches are also provided in the operator's cab 101, and the operator can set various modes such as a boom priority mode, a swing priority mode, a leveling mode, and a tamping mode. The most suitable one can be selected appropriately according to the work. In the normal case where such a selection is not made, the operation of the stick 104 is important in the operation of the construction machine, and it is necessary to give priority to this operation. ing. For example, when the operator operates these operating members 54, the control valves 57 to 60 and 62 to 65 interposed in the hydraulic circuit 53 are controlled, and each cylinder is controlled. 105 to 107 and hydraulic motors 109 L, 109 R, 110 are driven. As a result, the upper swing body 102 can be swung, the boom 103, the stick 104, the bucket 108, and the like can be swung, and the hydraulic excavator can run.

The member operated when rotating the boom 103 is the boom operating member 54a, and the member operated when rotating the stick 104 is the stick operating member 54b, the bucket 10b. An object to be operated when rotating 8 is a baguette operating member 54c, an object to be operated when rotating the upper revolving structure 102 is a swiveling operating member 54d, which is operated when traveling. Is referred to as a traveling operation member 54 e.

Next, a hydraulic circuit 53 for controlling these cylinders and the like will be described.

As shown in FIG. 2, the hydraulic circuit 53 includes a first circuit section 55 and a second circuit section.

5 and 6.

The first circuit section 55 includes an oil passage 61 connected to the first hydraulic pump 51, a right traveling motor control valve 57 interposed in the oil passage 61, and a baguette control valve. 58, a control valve for the first boom 59, a control valve for the second stick 60, and the like.

Then, the hydraulic oil from the first hydraulic pump 51 is supplied to the right traveling motor 109 R via the oil passage 61 and the right traveling motor evening control valve 57, and the right traveling motor 110 R is driven. The hydraulic oil from the first hydraulic pump 51 is supplied to the bucket driving hydraulic cylinder 107 via the oil passage 61 and the packet control valve 58, and the hydraulic oil is supplied to the oil passage 61 It is supplied to the boom drive hydraulic cylinder 105 via the boom control valve 59, and Is supplied to the stick driving hydraulic cylinder 106 via the oil passage 61 and the second stick control valve 60, thereby driving each cylinder 105, 106, 107 It has become.

In addition, the hydraulic passage 61 of the first circuit section 55 is provided with hydraulic oil that is not supplied to the hydraulic actuators 105 to 107 and 109R via the control valves 57 to 60, respectively. Oil passage 61b as a bypass passage for returning the oil to the tank 70. Then, as described later, the flow rate of the hydraulic oil flowing through the oil passage 61b is detected, and the discharge flow rate from the hydraulic pump 51 is controlled based on the detected flow rate of the hydraulic oil. .

Here, a throttle 81 is provided as a component of the bypass pressure detecting means in the oil passage 61b downstream of each of the control valves 57 to 60, and each of the control valves 57 to 60 is neutral. The hydraulic oil from the first hydraulic pump 51 is returned to the reservoir tank 70 through the throttle 81 in the position or the intermediate movement position (the position between the both-end movement position and the neutral position). Since the pressure in the bypass passage 6 1b on the upstream side of the throttle 81 changes according to the flow rate of the hydraulic oil flowing in the bypass passage 6 1b by the throttle 81, the bypass passage 6 By detecting the pressure in 1b by the pressure sensor 74 as a component of the bypass pressure detecting means, the flow rate of the hydraulic oil flowing in the bypass passage 61b is detected.

In this case, the flow rate of the hydraulic oil flowing in the bypass passage 61b is detected by detecting the pressure in the bypass passage 61b by the pressure sensor 74, but is not limited thereto. Instead, for example, the flow rate of the hydraulic oil flowing in the bypass passage 61b may be detected by a flow rate sensor.

The second circuit portion 56 includes an oil passage 66 connected to the second hydraulic pump 52, a left traveling motor control valve 62 interposed in the oil passage 66, and a swing motor control valve 6. 3, a control valve such as a first stick control valve 64, a second boom control valve 65, etc., and a throttle 82.

Then, the hydraulic oil from the second hydraulic pump 52 is supplied to the left traveling motor 109 L via the oil passage 66 and the left traveling motor control valve 62, whereby the left traveling motor is driven. Evening 109 L is to be driven. Hydraulic oil from the second hydraulic pump 52 is supplied to the swing motor 110 via the oil passage 66 and the swing motor control valve 63, thereby driving the swing motor 110. It has become to be. Further, the hydraulic oil from the second hydraulic pump 52 is supplied to the stick driving hydraulic cylinder 106 through the oil passage 66 and the first stick control valve 64, and the oil passage 66, It is supplied to the boom drive hydraulic cylinder 105 via the boom control valve 65, whereby the respective cylinders 105, 106 are driven.

In addition, the oil passage 66 of the second circuit section 56 is supplied to each hydraulic actuator 105, 106, 110, 109L via each control valve 62 to 65. It is provided with an oil passage 66 c serving as a bypass passage for returning the used hydraulic oil to the tank 70. Then, as described later, the flow rate of the hydraulic oil flowing through the oil passage 66c is detected, and the discharge flow rate from the hydraulic pump 52 is controlled based on the detected flow rate of the hydraulic oil.

Here, a throttle 82 is provided as a component of a bypass pressure detecting means in the bypass passage 66 c downstream of each of the control valves 62 to 65, and each of the control valves 62 to 65 is provided. Hydraulic oil from the second hydraulic pump 52 is returned to the reservoir tank 70 through the throttle 82 in the neutral position or the intermediate movement position (position between the both-end movement position and the neutral position). . Then, the pressure in the bypass passage 66 c on the upstream side of the throttle 82 changes in accordance with the flow rate of the hydraulic oil in the bypass passage 66 c due to the restriction 82, so that this bypass passage 6 The pressure in 6c is used as a component of the bypass pressure detection means. The flow rate of the hydraulic oil flowing in the bypass passage 66 c is detected by the detection by all the pressure sensors 75.

Here, the flow rate of the hydraulic oil flowing in the bypass passage 66c is detected by detecting the pressure in the bypass passage 66c by the pressure sensor 74, but is not limited thereto. Instead, for example, the flow rate of the hydraulic oil flowing in the bypass passage 66c may be detected by a flow rate sensor.

The control valves 57 to 60 and 62 to 65 are housed in a control unit (not shown).

As described above, in the present embodiment, the second stick is set so that a sufficient hydraulic oil is supplied to the important stick 104 in the operation of the construction machine even at the same time when the other work machine 118 is operated simultaneously. In addition to the hydraulic oil from the second hydraulic pump 52 in the circuit section 56, the hydraulic oil from the first hydraulic pump 51 in the first circuit section 55 is also supplied to the stick driving hydraulic cylinder 106. It has become.

For this reason, the first stick control valve 64 is interposed in the oil passage 66 of the second circuit portion 56, and the second stick control valve 60 is interposed in the oil passage 61 of the first circuit portion 55. Is equipped. The first stick control valve 64 is controlled by the proportional control valves 64a and 64b, and the second stick control valve 60 is controlled by the proportional control valves 60a and 60b. , So that hydraulic oil can be supplied to and discharged from the hydraulic cylinder 106 for driving the stick. Similarly, sufficient operation of the boom 103 can be performed simultaneously with other work equipment 118. In order to supply oil, in addition to the hydraulic oil from the first hydraulic pump 51 of the first circuit section 55, the hydraulic oil from the second hydraulic pump 52 of the second circuit section 56 is also used for boom drive. As a result, the control valve 59 for the first boom is interposed in the oil passage 61 of the first circuit section 55, and the oil in the second circuit section 56 is supplied to the hydraulic cylinder 105. The second boom control valve 65 is interposed in the road 66 Have been. The first boom control valve 59 is controlled by the proportional control valves 59a and 59b, and the second boom control valve 65 is controlled by the proportional control valves 65a and 65b. Hydraulic oil can be supplied to and discharged from the boom drive hydraulic cylinder 105.

In the present embodiment, a stick regeneration valve 76 is interposed in the oil passages 67 and 68 for supplying and discharging the hydraulic oil to and from the hydraulic cylinder 106 for driving the stick. A predetermined amount of hydraulic oil can be regenerated from the side oil passage to the hydraulic oil supply-side oil passage.

Similarly, boom regeneration valves 77 are also interposed in the oil passages 78, 799 that supply and discharge hydraulic oil to the boom drive hydraulic cylinder 105, and operate from the hydraulic oil discharge side oil passage. A predetermined amount of hydraulic oil can be regenerated to the oil supply side oil passage.

Here, each of the control valves 57 to 60 and 62 to 65 is configured as a spool valve as shown in Fig. 3, and each is configured with a plurality of (here, five) throttles. .

That is, as shown in FIG. 3, the control valves 57 to 60 and 62 to 65 are connected to the first hydraulic pump 51, the second hydraulic pump 52 and the stick driving hydraulic cylinder 106, respectively. Communicating oil passages (hydraulic oil supply passages, P-C passages) P-C throttles 40 interposed between 61a and 66a, stick drive hydraulic cylinders 106 and reservoir tanks 70 (Hydraulic oil discharge passage, C-T passage) 66 C, T throttle 41 interposed in 69, 69, first hydraulic pump 51, second hydraulic pump 52, and reservoir It is provided with a bypass passage restrictor 42 interposed in oil passages (bypass passages) 61b and 66c communicating with the tank 70.

In FIG. 3, the stick control valves 60 and 64 are in the stick lowered position, but the stick control valves 60 and 64 are moved upward in FIG. The stick control valves 60 and 64 can be set to the neutral position by moving the stick control valves 60 and 64 so that the bypass passage throttles 42 of the stick control valves 60 and 64 are interposed in the bypass passages 6 lb and 66 c. The stick control valves 60 and 64 are moved to the uppermost position in Fig. 3, and the P-C throttle 40 of the stick control valves 60 and 64 is interposed in the P-C passages 61a and 66a. At the same time, the C—T throttle 41 of the stick control valves 60 and 64 is interposed in the C-T passages 66 b and 69 to bring the stick control valves 60 and 64 to the stick raising position. Can be.

When setting the diameters of the apertures 40, 41, and 42, when the operation members 54 are fully operated in order to ensure the interlocking of the working machines 118 such as the boom 103 and the stick 104, It is taken into account that all implements 1 18 move.

The opening area of the oil passages 61 a and 66 a for connecting the first hydraulic pump 51 and the second hydraulic pump 52 to the stick driving hydraulic cylinder 106 by the P-C throttle 40 (the hydraulic oil supply passage). The opening area of P_C is adjusted.

The opening area of the oil passages 66 b, 69 (opening area of the hydraulic oil discharge passage, opening area of the C-T opening) that adjusts the communication between the stick driving hydraulic cylinder 106 and the reservoir tank 70 is adjusted by the C-T throttle 41. You.

The opening area (opening area of the bypass passage) of the oil passages 6 1 b and 66 c communicating the first hydraulic pump 51 and the second hydraulic pump 52 and the reservoir tank 70 is adjusted by the bypass passage throttle 42. You.

In the present embodiment, each of the control valves 57 to 60 and 62 to 65 is in the neutral position when none of the operating members 54 is operated, and the hydraulic oil from the hydraulic pumps 51 and 52 is provided. Is returned to sunset 70 through bypass passages 61b and 66c. On the other hand, any one of the operation members 54 is operated by the operator, and the control valves 57 to 60 and 62 to 65 are moved to the intermediate movement position (between the both-end movement position and the neutral position) according to the operation amount. Position, the opening area of the bypass passage 6 lb, 66 c is narrowed by the bypass passage restrictor 42, and the flow rate of the hydraulic oil returned to the tank 70 through the bypass passages 61 b, 66 c is reduced. On the other hand, the opening area of the hydraulic oil supply passage narrowed by the P-C throttle 40 becomes large, and the hydraulic oil supply passages 105 to 107, 1091, 109R, 110 through the hydraulic oil supply passage As the hydraulic oil is supplied, the opening area of the hydraulic oil discharge passage narrowed by the C_T throttle 41 increases, and the hydraulic oil is discharged to the tank 70 through the hydraulic oil discharge passage. As a result, the hydraulic oil is supplied to each hydraulic actuator 105 to 107, 109, 109 R, 110 so that each hydraulic actuator 105 to: L07, 109 1, 1 0 9 R, 1 1 0 are activated. The flow rate of the hydraulic oil supplied to each hydraulic actuator 105-: 107, 109, 109 R, 110 is controlled according to the amount of operation of each operating member 54 by the operator. Control valves 57 to 60 and 62 to 65.

Further, when each of the control valves 57 to 60 and 62 to 65 is set to the maximum movement position according to the amount of operation of each of the operation members 54 by the operator, the opening areas of the bypass passages 6 1 b and 66 c are closed, and the hydraulic pressure is reduced. Hydraulic oil from the pumps 51 and 52 is no longer returned to the tank 70 through the bypass passages 61 and 66c. On the other hand, the opening area of the hydraulic oil supply passage narrowed by the PC throttle 40 is maximized, and the hydraulic oil supply The flow rate of hydraulic oil supplied to each hydraulic actuator through the passageway from 105 to 107, 109, 109R, 110 is maximized, and is reduced by the CT throttle 41. The opening area of the hydraulic oil discharge passage is also maximized, and the operation is discharged to the tank 70 through the hydraulic oil discharge passage. The oil flow is also maximum. As a result, each hydraulic factor 105-107, 1091, 109R, 110 operates at the highest operating speed.

In this way, the hydraulic oil from the hydraulic pumps 51 and 52 is supplied to each hydraulic actuator 105-: L07, 1091, 109R, 110, which is as follows. Can also be considered. In other words, when the operator operates the operating member 54, the control valves 57 to 60 and 62 to 65 disposed in the hydraulic oil supply passage move accordingly, and the hydraulic actuator 105 to 1: 1. 07, 109 1, 109 R, 110 Hydraulic oil is supplied to R, 110, while hydraulic oil is supplied via control valves 57 to 60, 62 to 65, 105 to 107, 110, 109 It can also be considered that the hydraulic oil not supplied to 1, 109R, 110 is returned to the tank 70 through the bypass passages 61b, 66c.

By the way, in this embodiment, in order to control the control valves 57 to 60 and 62 to 65, as shown in FIG. 2, the pilot pump 83 and the proportional pressure reducing valves 57 a to 60 a, 57 b To 60b, 62a to 65a, and 62b to 65b. In Fig. 2, only the pilot pump 83 and the proportional pressure reducing valves 57a to 60a, 57b to 60b, 62a to 65a, and 62b to 65b provided in the pilot hydraulic circuit are shown. The pilot oil pressure is indicated by P, omitting the pilot oil passage.

Here, the proportional pressure reducing valves 57a to 60a, 57b to 60b, 62a to 65a, 62b to 65b are solenoid valves, and are operated by an operation signal from the controller 1 described later. Activated. Thus, the pilot oil pressure from the pilot pump 83 is applied to each of the control valves 57 to 60 and 62 to 65 as a predetermined pressure based on the operation signal from the controller 1. With such a configuration, for example, in order to turn the upper swing body 102, the turning operation member 54 d in the driver's operation room 101 is operated, and the pipe port from the pilot pump 83 is operated. The hydraulic pressure P is applied to the swing motor control valve 63 through a pilot oil passage (not shown) to move the swing motor control valve 63 to a required position. As a result, the supply and discharge of the hydraulic oil to and from the turning motor 110 are adjusted, whereby the turning motor 110 is operated.

For example, in order to turn the upper swing body 102 rightward, the swing motor 110 may be turned clockwise. In this case, the pilot hydraulic pressure is applied to the turning motor control valve 63 through the pilot oil passage. As a result, the rotary motor control valve 63 is set to the right turning position, and the hydraulic oil from the second hydraulic pump 52 of the second circuit portion 56 passes through the oil passages 66 a and 96, Hydraulic oil in the left oil chamber of the slewing motor 110 is supplied to the reservoir tank 70 via the oil passages 97, 66b while being supplied to the right oil chamber of the slewing motor 110. . As a result, the turning motor 110 is turned clockwise, and the upper turning body 102 turns right.

Conversely, in order to turn the upper swing body 102 leftward, the swing motor 110 may be turned counterclockwise. In this case, the pilot hydraulic pressure is applied to the turning motor control valve 63 through the pilot oil passage. As a result, the turning motor control valve 63 becomes the left turning position, and the hydraulic oil from the second hydraulic pump 52 of the second circuit section 56 passes through the oil passages 66 a and 97 to turn the turning motor. While the oil is supplied to the left oil chamber of evening 110, the hydraulic oil in the right oil chamber of turning motor 110 is discharged to reservoir tank 70 via oil passages 966 and 66b. As a result, the swing motor 110 is turned counterclockwise, and the upper swing body 102 is turned left.

Further, in order to maintain the current state of the upper revolving superstructure 102, the pilot hydraulic pressure is applied to the swing motor control valve 63 as appropriate to control the swing motor control valve 63 The position of the spool may be set to the neutral position (the hydraulic supply / discharge path shutoff position). As a result, the supply and discharge of the hydraulic oil in each oil chamber of the turning motor 110 is stopped, and the upper turning body 102 is held at the current position.

By the way, various sensors are attached to the construction machine configured as described above, and a detection signal from each sensor is sent to a controller 1 described later.

For example, an engine 50 for driving the hydraulic pumps 51 and 52 is provided with an engine speed sensor 71, and a detection signal from the engine speed sensor 71 is sent to a controller 1 described later. And so on. The controller 1 performs feedback control so that the actual engine speed becomes the target engine speed set by the operator with the engine speed setting dial.

The discharge side of the first hydraulic pump 51 of the first circuit unit 55 and the second hydraulic pump 52 of the second circuit unit 56 are provided with pressure sensors (PZS-P 1) 72, and a pressure sensor (PZS-P2) 73 are provided, and detection signals from these pressure sensors 72, 73 are sent to a controller 1 described later.

In addition, the downstream side of each control valve 57-60 of the oil passage 61 as one bypass passage from the hydraulic pump 51 of the first circuit portion 55 to the tank 70 and the second circuit portion 56 Downstream of each of the control valves 62 to 65 of the oil passage 66 as one bypass passage from the hydraulic pump 51 to the tank 70, a pressure sensor (PZS- N 1) 74 and a pressure sensor (PZS-N 2) 75 are provided. Detection signals from these pressure sensors 74 and 75 are sent to the controller 1 described later. I have.

In addition, oil for supplying and discharging hydraulic oil to and from the boom drive hydraulic cylinder 105 A pressure sensor (PZS-BMd) 80 is provided on the road, and the pressure sensor 80 can detect the rod-side pressure (load pressure) of the hydraulic cylinder 105 for driving the boom. The detection signal from the pressure sensor 80 is sent to the controller 1 described later.

In the present embodiment, a controller 1 is provided to control the construction machine configured as described above.

The controller 1 controls the first hydraulic pump 51, the second hydraulic pump 52, the regeneration valves 76, based on the detection signals from the sensors 71 to 75, 80 and the electric signals from the operating member 54. 7 7, By outputting operation signals to the control valves 57 to 60 and 62 to 65, the tilt angles of the first hydraulic pump 51 and the second hydraulic pump 52 are controlled, and the control valves 57 to 60 are controlled. , 62 to 65, and the position control of each regeneration valve 76, 77.

Here, as shown in FIG. 1, the controller 1 has a function as a function of processing an electric signal from each operation member 54 in order to control the tilt angle of the first and second hydraulic pumps 51, 52. Operation member signal processing means 2, first hydraulic pump tilt angle control means 3 as a function of controlling the tilt angle of first hydraulic pump 51, and function of controlling the tilt angle of second hydraulic pump 52 And the second hydraulic pump tilt angle control means 4. Since the first hydraulic pump tilt angle control means 3 and the second hydraulic pump tilt angle control means 4 both control the discharge flow rate from the hydraulic pump, they are also referred to as pump flow rate control means.

Of these, as shown in FIG. 1, the operating member signal processing means 2 is configured to operate each of the operating members 54 & 54 d, 54 e-R, 54 e-L when each of the operating members 54 & 54 e is operated. To 54 (1, 54 e-R, 54 e-L) Set the travel of each control valve 57 to 60 and 62 to 65 based on the electric signal corresponding to the manipulated variable of It outputs a control signal to the control valves 57 to 60, 62 to 65 and the tilt angle setting means 6, 11 corresponding to the operation member described later.

The operating member signal processing means 2 is used to simultaneously operate a plurality of hydraulic factories 105 to 107, 109R, 109L, 110 when operating a plurality of hydraulic factories simultaneously. Functions as a setting for speed balance (flow distribution).

Here, the flow rate distribution is determined according to the operation pattern of the plurality of operation members 54a to 54d, 54e-R, and 54e-L and the operation amount thereof. Set the speed balance (flow balance) of 9R, 1109L, 110 with priority. The priority can be set arbitrarily. For example, if all operating members that simultaneously operate the boom 103, the stick 104, and the bucket 108 are fully operated, the pump discharge flow rate is the maximum flow rate, and the flow balance is 50% for the boom. You can set it like stick 30%, bucket 20%.

As shown in FIG. 1, the first hydraulic pump tilt angle control means 3 includes a bypass pressure tilt angle setting means 5, an operating member tilt angle setting means 6, and a speed corresponding pump tilt angle setting. Means 7, a permissible horsepower displacement angle setting means 8, and a minimum value selection means 9 are provided to output a pump displacement angle control signal Fp1 to the first hydraulic pump 51.

Among them, the bypass pressure corresponding tilt angle setting means 5 sets the pump tilt angle based on the bypass pressure detection signal.

As shown in FIG. 4, the tilt angle setting means 5 corresponding to the bypass pressure includes, as shown in FIG. 4, hydraulic fluid in the bypass passage 6 1 b of each of the control valves 57 to 60 which operates according to the operation amount of each operation member 54. The output signal (E) is input from the pressure sensor 74 as the bypass pressure detecting means 81, 74 for detecting the pressure, and the pump is tilted based on the characteristic inversely proportional to the output signal (E). Turning angle A first control signal F-1 is set as a pump tilt angle control signal for controlling the pump flow rate, and is output to the speed control corresponding tilt angle setting means 7.

The pump tilt angle control (pump flow control) performed based on the characteristic that is substantially inversely proportional to the flow rate of the hydraulic oil in the bypass passage 61b is referred to as negative flow control. Here, the substantially inversely proportional characteristic includes not only a curved characteristic as a general inversely proportional characteristic but also, for example, a characteristic that changes linearly, and this characteristic includes the hydraulic oil in the bypass passage 6 lb. It is only necessary that the characteristics be such that the pump tilt angle decreases as the pressure increases.

Here, the bypass pressure detecting means 81, 74 is composed of a restrictor 81 and a pressure sensor 74 located upstream of the restrictor 81, and as shown in FIG. It detects the output signal (E) of the pressure sensor 74 which changes in proportion to the sum of the bypass flow rates) (D). The aperture area of the diaphragm 81 is set in advance as a fixed value.

As described above, the restriction 81 and the pressure sensor 74 constitute the bypass pressure detecting means because, as described above, the bypass path restriction 42 of each of the control valves 57 to 60 is formed by the oil path 61b. Are connected in series with each other, and when a plurality of operating members 54 are simultaneously operated, the bypass flow rate is the sum (D) of the throttles sequentially obtained by the control valves 57 to 60 and the bypass flow rate Because it flows into the throttle 81 located downstream of the passage 6 1 b, the upstream flow rate of the throttle 81 increases as the flow rate through the throttle 81 (the sum of bypass flow rates) increases. On the other hand, if the flow rate through the throttle 81 (the sum of the bypass flow rates) D decreases, the pressure upstream of the throttle 81 decreases, and thus increases in accordance with the flow rate through the throttle 81. This is because the pressure sensor 74 detects the pressure on the upstream side of the restrictor 81, which increases or decreases. As shown in FIG. 5, the control member corresponding tilt angle setting means 6 receives the control signals of the respective control valves 57 to 60 (the operation amounts of the respective operation members 54) from the operation member signal processing means 2, as shown in FIG. These control signals are used to input the control signals to the control valves 57 to 60 based on the characteristics directly proportional to the control signals (the operation amounts of the operation members 54) of the control valves 57 to 60. The required flow rate (required pump tilt angle) to be supplied to each actuator 105 to 107, 109 R through 60 is determined, and this is used as a pump tilt angle control signal based on the operation amount of the operating member. This is set as the second control signal F②-1 and output to the speed control corresponding tilt angle setting means 7.

The pump tilt angle control (pump flow rate control) performed based on the characteristic that is substantially directly proportional to the operation amount of the operation member 54 as described above is referred to as positive flow control. Here, the substantially directly proportional characteristic includes not only a linear characteristic as a general directly proportional characteristic but also, for example, a characteristic that changes in a curved shape, and this characteristic increases as the operation amount of the operation member 54 increases. Any characteristics may be used as long as the pump tilt angle becomes large.

In addition, the control signals (operation amounts of the respective operation members 54) of the respective control valves 57 to 60 from the operation member signal processing means 2 are, for example, a plurality of hydraulic actuators 105 to 107, 10. When the 9Rs are simultaneously operated, the optimal flow distribution is performed by the operation member signal processing means 2 as described above, so that a control signal corresponding to this flow distribution is transmitted to the operating member corresponding tilt. This is input to the turning angle setting means 6.

Here, the required flow rate characteristic, which is directly proportional to the control signal of each control valve 57 to 60 (the operation amount of each operation member 54), is set for each control valve 57 to 60 as shown in FIG. Have been. Then, when a plurality of operating members 54 are operated to set control signals to the control valves 57 to 60, the control signals are supplied to the control valves 57 to 60 based on the characteristics directly proportional to the control signals. Required flow rate and sum them Then, the pump flow rate to be discharged by the hydraulic pump 51 (pump tilt angle) F ②—1 is calculated. "

The speed-dependent pump tilt angle setting means 7 is used to control the pump tilt angle of the first hydraulic pump 51 for speed control of each actuator 105 to 107, 109R. A speed-dependent control signal F11eVer is set as the pump tilt angle control signal.

Here, the speed corresponding control signal F11eVer controls the speed of each hydraulic actuator 105 to 107,109R under a load condition (pump operation condition) below the allowable horsepower. This is a pump tilt angle control signal for controlling the pump tilt angle (pump flow rate) according to the operation amount of each operation member 54 in order to perform the operation.

Here, as shown in FIG. 6, the speed-dependent pump tilt angle setting means 7 includes a minimum signal selecting means 20, a required tilt angle comparing means 21, a minimum signal output means 22, and a predetermined value. It is provided with setting means 23 and required tilt angle output means 24, and sets the speed corresponding control signal F11 eVer as the pump tilt angle control signal for speed control of the actuator. And outputs it to the minimum value selecting means 9.

Among these, the minimum signal selecting means 20 includes a first control signal F-1 as a bypass flow rate based pump tilt angle control signal from the bypass pressure corresponding tilt angle setting means 5 and a tilt corresponding to the operation member. One control signal is selected from the two control signals F②-1 and the second control signal F②-1 as the pump displacement angle control signal based on the operation member operation amount from the angle setting means 6. _c The first control signal F-1 is used to control the pump tilt angle based on a characteristic inversely proportional to the pressure of the hydraulic oil in the bypass passage 6 1 b (negative flow control). Angle control signal, and the second control signal F②-1 is based on a characteristic that is directly proportional to the operation amount of the operation member 54. A pump displacement angle control signal for controlling the displacement angle (positive flow control), and the minimum signal selecting means 20 selects one of the negative flow control and the positive flow control. Therefore, it is also called negative control and positive control selection means.

Here, the minimum signal selection means 20 includes a first control signal F①-1 from the bypass pressure corresponding tilt angle setting means 5 and a second control signal F② from the operation member corresponding tilt angle setting means 6. Compared with —1, the smaller control signal is output to the minimum signal output means 21 as the minimum control signal F min. In other words, the minimum signal selecting means 20 determines that the second control signal F②1 based on the operation member operation amount is smaller than the first control signal F①-1 based on the bypass flow rate (F 11 <F ®— 1) outputs the second control signal F②-1 based on the operation member operation amount to the minimum signal output means 21 as a minimum control signal Fmin, and outputs the second control signal F②-1 based on the operation member operation amount. If the bypass flow-based first control signal F①—1 is greater than (F②—1> F ® _ 1), the bypass flow-based first control signal F①—1 is the minimum control signal F min and the minimum signal Output to the output means 21.

More specifically, the minimum signal selecting means 20 is based on a characteristic diagram showing the relationship between the load pressure of the working machine (hydraulic factory) and the working machine speed (working speed) as shown in FIG. 7 (c). Control signal to reduce the pump tilt angle of the first control signal F①-1 and the second control signal F②-1 (the control signal to reduce the pump flow rate). ) Is used to control the pump tilt angle (pump flow rate).

As a result, as shown in FIG. 7 (c), when the load pressure decreases, the first control signal F①_1 changes in the direction to increase the pump tilt angle, while the second control signal F②-1 changes. Since it is constant regardless of load pressure fluctuation, The signal that makes the pump tilt angle small (that is, the second control signal F②-1) is selectively used. Therefore, when the load pressure decreases, the maximum work machine speed (pump flow rate) does not fluctuate even if the load pressure fluctuates, because it is controlled by the second control signal F②-1.

On the other hand, as shown in FIG. 7 (c), when the load pressure increases, the first control signal F①-1 changes in a direction to decrease the pump tilt angle, while the second control signal F②-1 Since the first control signal F①-1 is smaller than the second control signal F 負荷 -1 and is constant irrespective of the change in load pressure, a signal in which the pump tilt angle becomes smaller [ie, the first Control signal F①-1] is selected and used. Therefore, as the load pressure increases, the speed of the work equipment decreases, and there is an advantage that the magnitude of the load can be sensed throughout the operation (load-sensitive feeling).

The pump tilt angle control is performed based on the characteristic shown in FIG. 7 (c) for the following reason.

Here, Fig. 7 (a) shows the first control signal F that is inversely proportional to the bypass flow rate.

Fig. 6 is a diagram showing the relationship between the load (load pressure applied to the work implement) W and the work implement speed (pump displacement angle, pump flow rate) when performing the pump tilt angle control using ①-1. . In FIG. 7 (a), the broken line indicates the expected speed of the working machine according to the operation amount of the operation member 54.

As described above, the bypass flow rate varies under the influence of the load pressure, so that the pump flow rate (pump tilt angle) controlled based on the first control signal F①-1 based on the bypass flow rate also varies. Will be. Therefore, the relationship between the load pressure and the work implement speed is as shown in Fig. 7 (a), and the work implement speed (pump tilt angle, pump flow rate) constantly fluctuates as the load pressure fluctuates. Become.

For this reason, work equipment that can easily change the load pressure (eg, inertia load) In the case of a rotating system mainly composed of a load, the speed of the working machine also fluctuates, and as a result, problems such as hunting tend to occur. In other words, fluctuations in the pump flow rate (pump tilt angle) controlled by the bypass flow rate-based signal, which fluctuates with the load pressure, promote the hunting phenomenon.

On the other hand, the first control signal F−

When performing pump tilt angle control using (1), in excavation work, etc., where viscous loads in which the load pressure changes relatively stably are mainly used, when the load W increases, the work equipment speed decreases. The advantage is that the magnitude of the load can be sensed during the operation (load-sensitive feeling).

On the other hand, the second control signal F directly proportional to the operation amount of each operation member 54

Fig. 7 (b) shows the relationship between the work pressure and the load pressure when using 1--1. In other words, the pump flow rate (pump tilt angle) is controlled based on the signal from each operating member 54 and is independent of the load pressure fluctuation. ), It is constant within the allowable horsepower range.

In this case, there is no problem such as a sudden change in the working machine speed or hunting because there is no effect of fluctuations in the load pressure, but on the other hand, advantages such as sensing the magnitude of the load during the operation (load-sensitive feeling). There is no.

For this reason, in the present embodiment, in order to be able to enjoy both the advantages of the positive flow control and the advantages of the negative flow control, the pump is tilted based on the characteristic shown in FIG. 7 (C). Angle control was performed.

As a result, it is possible to suppress a sudden increase in the working machine speed due to a decrease in the load W and a hunting phenomenon caused by the increase, and to ensure a load-sensitive filling with the increase in the load W. become.

This type of control ensures that the operator achieves medium machine speed. For this purpose, it is suitable for pump tilt angle control under the condition that each operating member 54 is fixed at a fixed value near the middle position of the operating range.

The required tilt angle comparing means 21 includes a second control signal F②-1 based on the operation member operation amount from the operating member corresponding tilt angle setting means 6 and a predetermined value set by the predetermined value setting means 23. F 1 a 1 1 ow and outputs the comparison result to the minimum signal output means 22 and the required tilt angle output means 24. Is determined, and either the control signal Fmin selected by the minimum signal selecting means 20 or the second control signal F2 set by the operating member corresponding tilt angle setting means 6 is selected. The control signal will be used as the pump tilt angle control signal.

Since the second control signal F②_1 based on the operation member operation amount is equivalent to the pump tilt angle corresponding to the operation amount of the operation member 54 by the operator, the required tilt angle requested by the operator is used. Becomes the pump tilt angle control signal corresponding to.

Here, the required tilt angle comparing means 21 is configured to output the second control signal F②-1 from the operating member corresponding tilt angle setting means 6 to a predetermined value F 1 a 1 l set by the predetermined value setting means 23. If it is determined that the value is greater than ow (F②-l> F ll ow), the result of the determination is output to the minimum signal output means 22 while the predetermined value F 1 a 1 1 set by the predetermined value setting means 23 If it is determined that ow is larger than the second control signal F②-1 from the operation member corresponding tilt angle setting means 6 (F ②—l <F lall ow), the determination result is output to the required tilt angle output means. Output to 24.

Thus, the second control signal F②_1 corresponding to the tilt angle required by the operator is a predetermined value? When 1 & 1 1 ow or less, the second control signal F②-1 is selected regardless of the first control signal F①1 1 This is because the second control signal F②-1 is a speed control signal Fl 1 as a pump tilt angle control signal for the speed control of the hydraulic actuators 105 to 107, 109 R. By controlling the pump tilt angle (pump flow rate) as ever, it is possible to suppress changes in work machine speed (work speed) due to pump control due to load fluctuations in the fine operation range. That's why. In other words, the second control signal F②-1 based on the operation member operation amount is independent of the change in the load pressure of the work machine (the hydraulic actuator), and if the operation member operation amount is constant, the load W changes. Therefore, by performing the pump tilt angle control using the second control signal F②-1 as shown in FIG. 7 (d), even if the load W fluctuates, the working machine speed ( Pump flow rate and pump tilt angle) can be kept constant, and changes in work equipment speed (work speed) caused by pump tilt angle control due to load fluctuations in the fine operation range can be suppressed. It is. Note that, in FIG. 7D, the broken line indicates the work implement speed with respect to the load W when the pump tilt angle control is performed using the predetermined value F1a11ow as the pump tilt angle control signal.

This is the case when operating the working machine (hydraulic factory) at a very low speed such as a suspending operation and at a constant speed, with each operating member 54 fixed at a fixed value within the operating range below a predetermined value. Are suitable.

By the way, the predetermined value setting means 23 determines the allowable horsepower characteristic (horsepower limit allowable value) of the pump tilt angle (pump flow rate) as shown in FIG. 6 at the allowable maximum pressure point Pmax of the pump discharge pressure at W1. The predetermined value F1a11ow is set as a value corresponding to an arbitrary pump tilt angle (predetermined tilt angle) equal to or less than the pump allowable tilt angle (pump allowable flow rate) Flw. The predetermined value F1a11ow is set in advance.

Here, the pump allowable tilt angle (pump allowable flow rate) F lw is obtained by the following equation. F lw = Wl ÷ Pma x

As described above, the predetermined value F lal 1 ow is set as a value corresponding to an arbitrary pump tilt angle equal to or smaller than the pump allowable tilt angle F 1 w, because the pump control accompanying the load fluctuation in the fine operation range is performed. This is to suppress the change in work machine speed caused by the

The setting of the predetermined value F1a11ow is not limited to this, and may be set arbitrarily according to the characteristics of various working machines (tools). The minimum signal output means 22 outputs the minimum control signal Fmin from the minimum signal selection means 20 to the minimum value selection means 9 according to the determination result by the required tilt angle comparison means 21.

Things. In other words, the minimum signal output means 22 permits the output of the minimum control signal Fmin from the minimum signal selection means 20 to the minimum value selection means 9 according to the determination result by the required tilt angle comparison means 21. .

For this reason, the minimum signal output means 22 supplies the second control signal F-1 based on the operation member operation amount by the required tilt angle comparison means 21 to be larger than the predetermined value F1a110w ( F②—1> F 1 a 1 1 ow), the judgment result is input, and when this signal is input, the minimum control from the minimum signal selecting means 20 is performed. The signal Fmin is output to the minimum value selection means 9 as a speed-related control signal F11eVer for speed control in the evening.

The required displacement angle output means 24 outputs a predetermined value F lail ow larger than the second control signal F②-1 based on the operation member operation amount by the required displacement angle comparison means 21 (F②-l <F lall ow). Is determined, the result of the determination is input, and in response to this, the second control signal F 操作 -1 based on the operation member operation amount is changed to a speed-related control signal F for speed control of the actuator. It is output to the minimum value selection means 9 as 11 e Ver. The allowable horsepower corresponding tilt angle setting means 8 sets an allowable horsepower corresponding control signal F 1 power based on the allowable horsepower limit as a pump tilt angle control signal for controlling the tilt angle of the first hydraulic pump 51. Then, it outputs the permissible horsepower corresponding control signal F 1 p 0 wer to the minimum value selecting means 9 described later. Here, the allowable horsepower corresponding control signal F 1 power based on the allowable horsepower limit is an upper limit pump tilt angle control signal that is limited according to the allowable horsepower of the engine 50 that drives the first hydraulic pump 51. . That is, the control signal F 1 power corresponding to the allowable horsepower based on the allowable horsepower limit is set to the first hydraulic pump 5 according to the speed corresponding control signal F 11 eV er selected by the speed corresponding pump tilt angle setting means 7. When the pump tilt angle (1) is controlled, the pump tilt angle (pump flow rate) is adjusted so that the load W applied to the engine 50 that drives the first hydraulic pump 51 does not exceed the allowable horsepower of the engine 50. This is a pump tilt angle control signal for controlling.

For this reason, as shown in FIG. 8, the allowable horsepower corresponding tilt angle setting means 8 stores the allowable horsepower preset based on the engine horsepower of the engine 50 that drives the first hydraulic pump 51. The horsepower storage unit 8A and the permissible horsepower tilt angle calculation unit 8B are provided. The permissible horsepower tilt angle calculation unit 8B has a pump discharge pressure signal detected by the pressure sensor 72. Is input.

The allowable horsepower corresponding tilt angle calculation unit 8B is provided with a pump allowable horsepower storage unit 8

Based on the permissible horsepower W1 from A and the pump discharge pressure P1 from the pressure sensor 72, the permissible horsepower control signal based on the permissible horsepower limit (permissible flow rate control signal) F1power is expressed by the following equation. Is calculated by the following formula.

F 1 p o w e r = W 1 ÷ P 1

The allowable horsepower limitation-based control signal Flpower calculated in this manner is based on the allowable horsepower limitation-based allowable horsepower as shown in Fig. 8. This is represented as a characteristic diagram in which the corresponding control signal F 1 power is associated with the pump discharge pressure P 1. Note that, in the characteristic diagram shown in FIG. 8, the straight line indicated by the symbol A indicates the maximum tilt angle (maximum discharge flow rate) of the pump.

The minimum value selecting means 9 includes a speed corresponding control signal F11 eVer set by the speed corresponding pump tilt angle setting means 7 and an allowable horsepower corresponding control set by the allowable horsepower corresponding tilt angle setting means 8. Compare the signal F 1 power and select a control signal that reduces the pump tilt angle (a control signal that reduces the pump flow rate) and set this as the final pump tilt angle control signal F p 1 Then, the output is output to the first hydraulic pump 51.

The second hydraulic pump tilt angle control means 4 is configured similarly to the first hydraulic pump tilt angle control means 3 described above.

In other words, as shown in FIG. 1, the second hydraulic pump tilt angle control means 4 includes a bypass pressure setting tilt angle setting means 10, an operation member corresponding tilt angle setting means 11, and a speed corresponding pump tilt angle. It comprises a turning angle setting means 12, an allowable horsepower tilt angle setting means 13, and a minimum value selecting means 14, and sends a pump tilt angle control signal F p 2 to the second hydraulic pump 52. Output.

Among these, the bypass pressure-dependent tilt angle setting means 10 sets the pump tilt angle based on the bypass pressure detection signal, and the bypass pressure-dependent tilt angle setting means 5 includes, as shown in FIG. In addition, the pressure as the bypass pressure detecting means 82, 75 for detecting the pressure of the hydraulic oil in the bypass passage 66c of each control valve 62 to 65 operated in accordance with the operation amount of each operating member 54 An output signal (E) is input from the sensor 75, and the pump tilt angle (pump flow rate) is controlled based on characteristics inversely proportional to the output signal (E). The first control signal F①-2 as a control signal is set and output to the speed control-compatible tilt angle setting means 12.

In this way, the flow rate is approximately inversely proportional to the flow rate of hydraulic oil in the bypass passage 66c. The pump tilt angle control (pump flow rate control) performed based on these characteristics is called negative flow control. Here, the substantially inversely proportional characteristic includes not only a curved characteristic as a general inverse proportional characteristic but also, for example, a characteristic that changes linearly, and this characteristic is determined by the operation in the bypass passage 66c. The characteristic should be such that the pump tilt angle decreases as the oil pressure increases.

Here, the bypass pressure detecting means 82, 75 is composed of a restrictor 82 and a pressure sensor 75 located upstream of the restrictor 82, and as shown in FIG. It detects the output signal (E) of the pressure sensor 75 that changes in proportion to the sum of the bypass flow rates) (D). The aperture area of the stop 82 is set in advance as a fixed value.

As described above, the restrictor 82 and the pressure sensor 75 constitute the bypass pressure detecting means because, as described above, the bypass restrictors 42 of the control valves 62 to 65 are connected to the oil passages 66c. Are connected in series, and the bypass flow rate when a plurality of operating members 54 are operated at the same time is the sum (D) of the throttled values by each of the control valves 62 to 65. Because it flows into the restriction 82 located downstream of the passage 66 c, if the flow rate through the restriction 82 (the sum of the bypass flow rates) D increases, the upstream pressure of the restriction 82 increases. On the other hand, if the flow rate through the throttle 82 (the sum of the bypass flow rates) D decreases, the pressure on the upstream side of the throttle 82 decreases, and thus increases in accordance with the flow rate through the throttle 82. This is because the pressure sensor 75 detects the pressure on the upstream side of the restrictor 82 that decreases or decreases.

As shown in FIG. 5, the tilt angle setting means 11 corresponding to the operating member receives control signals (operating amounts of the operating members 54) of the control valves 62 to 65 from the operating member signal processing means 2 as shown in FIG. These control signals are used in direct proportion to the control signals of the control valves 62 to 65 (the operation amounts of the operation members 54). The necessary flow rate (required pump tilt angle) to be supplied to each actuator 106, 109L, 110 through each control valve 62 to 65 is determined based on the characteristics This is set as a second control signal F-2 as a pump displacement angle control signal based on the manipulated variable, and is output to the speed control-compatible displacement angle setting means 12.

Also, the control signals of the respective control valves 62 to 65 (the operation amounts of the respective operation members 54) from the operation member signal processing means 2 may be, for example, a plurality of hydraulic actuators 106, 109L, 1L. When 10 is simultaneously operated, the optimal flow distribution is performed by the operating member signal processing means 2 as described above, and thus a control signal corresponding to this flow distribution is transmitted to the operating member corresponding tilt. This is input to the turning angle setting means 11.

Here, the required flow rate characteristics that are directly proportional to the control signals of the control valves 62 to 65 (the operation amounts of the operation members 54) are set for each of the control valves 62 to 65 as shown in FIG. Have been. Then, when a plurality of operating members 54 are operated to set control signals to the control valves 62 to 65, the control signals are supplied to the control valves 62 to 65 based on the characteristic directly proportional to the control signals. The required flow rates to be obtained are obtained, and these are summed up to calculate the pump flow rate (pump tilt angle) F2—2 to be discharged by the hydraulic pump 52.

Speed-dependent pump tilt angle setting means 1 2

1 9 L, 2 1 hydraulic pump for 110 speed control 5 2 pump In order to control the tilt angle, a speed-related control signal F21eVer is set as the pump tilt angle control signal.

Here, the speed-related control signal F21eVer is set to a speed of 106, 109L, 110 of each hydraulic actuator under a load condition (pump operating condition) below the allowable horsepower. This is a pump tilt angle control signal for controlling the pump tilt angle (pump flow rate) in accordance with the operation amount of each operation member 54 in order to control the pump tilt angle.

Here, as shown in FIG. 6, the speed-dependent pump tilt angle setting means 12 includes a minimum signal selecting means 20, a required tilt angle comparing means 21, a minimum signal output means 22, and a predetermined value. It is provided with a setting means 23 and a required displacement angle output means 24 and is provided with a speed corresponding control signal F 21 eV er as a pump displacement angle control signal for speed control of the actuator. Set and output to the minimum value selection means 14.

Among these, the minimum signal selecting means 20 includes a first control signal F−2 as a bypass flow rate based pump tilt angle control signal from the bypass pressure corresponding tilt angle setting means 10 and a tilt corresponding to the operation member. Operation section from shift angle setting means 1 A second control signal as a pump tilt angle control signal based on the operation amount of material, and selects one control signal from the two control signals F-2. It is.

Note that the first control signal F①-2 is a pump tilt angle for controlling the pump tilt angle (negative flow control) based on a characteristic that is inversely proportional to the flow rate of the hydraulic oil in the bypass passage 66 c. The second control signal F−2 is a pump tilt angle control signal for controlling the pump tilt angle (positive flow control) based on characteristics directly proportional to the operation amount of the operation member 54. Yes, the minimum signal selection means 20 selects either negative flow control or positive flow control. It is also called negative control Z positive control selection means.

Here, the minimum signal selecting means 20 includes a first control signal F−2 from the bypass pressure corresponding tilt angle setting means 10 and a second control signal from the operating member corresponding tilt angle setting means 11. Compared with the signal F 比較 -2, the smaller control signal is output to the minimum signal output means 21 as the minimum control signal Fmin. In other words, the minimum signal selecting means 20 determines that the second control signal F②−2 based on the operation member operation amount is smaller than the first control signal F①−2 based on the bypass flow rate (F−2 <F (D− 2) outputs the second control signal F②—2 based on the operation member operation amount to the minimum signal output means 21 as the minimum control signal F min, and outputs the second control signal F②—2 based on the operation member operation amount. When the first control signal based on the bypass flow rate is larger than F①-2 (F②-2> F ® _ 2), the first control signal F-2 based on the bypass flow rate is minimized as the minimum control signal F min The signal is output to the signal output means 21.

More specifically, the minimum signal selecting means 20 is based on a characteristic diagram showing the relationship between the load pressure of the working machine (hydraulic factory) and the working machine speed (working speed) as shown in FIG. 7 (c). Control signal to reduce the pump tilt angle of the first control signal F①-2 and the second control signal F②-2 (the control signal to reduce the pump flow rate). ) Is used to control the pump tilt angle (pump flow rate).

As a result, as shown in FIG. 7 (c), when the load pressure decreases, the first control signal F①-2 changes in a direction to increase the pump tilt angle, while the second control signal F②-2 changes. Since it is constant irrespective of the change in the load pressure, a signal that makes the pump tilt angle small (that is, the second control signal F−2) is selectively used. Therefore, when the load pressure decreases, the maximum work machine speed is controlled even when the load pressure fluctuates because the load pressure is controlled by the second control signal F−2. Mode (pump flow rate) does not fluctuate.

On the other hand, as shown in FIG. 7 (c), when the load pressure increases, the first control signal F①-2 changes in a direction to decrease the pump tilt angle, while the second control signal F②-2 Since the first control signal F①-2 is constant irrespective of the fluctuation of the load pressure, the first control signal F①-2 becomes smaller than the second control signal F 2-2, and the signal in which the pump tilt angle becomes small [ie, the first Control signal F-2] is selected and used. Therefore, there is an advantage that the work machine speed decreases as the load pressure increases, and the operator can sense the magnitude of the load (load-sensitive feeling).

Fig. 6 is a diagram showing the relationship between the load (load pressure applied to the working machine) W and the working machine speed (pump tilt angle, pump flow rate) when performing the pump tilt angle control using (1) -2. . In FIG. 7 (a), the broken line indicates the expected speed of the working machine according to the operation amount of the operation member 54.

As described above, since the bypass flow rate fluctuates under the influence of the load pressure, the pump flow rate (pump tilt angle) controlled based on the bypass flow rate-based first control signal F①-2 also fluctuates. Will be lost. Therefore, the relationship between the load pressure and the work implement speed is as shown in Fig. 7 (a), and the work implement speed (pump tilt angle, pump flow rate) constantly fluctuates as the load pressure fluctuates. Become.

For this reason, in a working machine in which the load pressure fluctuates easily (for example, a turning system mainly composed of inertial load), the working machine speed also fluctuates, and as a result, problems such as hunting are likely to occur. . In other words, the pump flow rate controlled by the bypass flow rate based signal that varies with the load pressure (Pump tilt angle) The fluctuation promotes the hunting phenomenon.

On the other hand, when the pump tilt angle control is performed using the first control signal F①−2 that is inversely proportional to the bypass flow rate as described above, the excavation is mainly performed by a viscous load whose load pressure changes relatively stably. In work, etc., there is an advantage that when the load W increases, the work machine speed decreases, and the operator can sense the magnitude of the load (load-sensitive feeling).

On the other hand, the relationship between the load pressure and the working machine speed when the second control signal F2—2, which is directly proportional to the operation amount of each operation member 54, is as shown in FIG. 7 (b). In other words, the pump flow rate (pump tilt angle) is controlled based on the signal from each operating member 54 and is independent of the load pressure fluctuation. ), It is constant within the allowable horsepower range.

In this case, there is no problem such as a sudden change in the working machine speed or hunting because there is no effect of fluctuations in the load pressure. On the other hand, advantages such as allowing the operator to sense the magnitude of the load (load-sensitive feeling) are also obtained. Absent.

For this reason, in the present embodiment, in order to be able to enjoy both the advantages of the positive flow control and the advantages of the negative flow control, the pump is tilted based on the characteristics as shown in FIG. 7 (c). Angle control was performed.

As a result, it is possible to suppress a sudden increase in the working machine speed due to a decrease in the load W and a hunting phenomenon induced by the increase, and also to secure a load-sensitive filling with the increase in the load W. become. Such control is intended to obtain a medium working machine speed by the operator, and the pump tilts under the condition that each operating member 54 is fixed at a fixed position near the middle position of the operating range. Suitable for angle control.

The required tilt angle comparing means 21 is provided from the operating member corresponding tilt angle setting means 11. The second control signal F−2 based on the operation member operation amount is compared with the predetermined value F 2 a 1 ow set by the predetermined value setting unit 23, and the comparison result is compared with the minimum signal output unit 22 and the request. This is output to the tilt angle output means 24. Thus, it is determined what kind of work the operator is requesting, and the control signal Fmin selected by the minimum signal selecting means 20 and the tilting angle setting means 11 corresponding to the operating member are used. One of the set second control signals F②−2 is used as the pump tilt angle control signal.

The second control signal F②−2 based on the operation member operation amount is equivalent to the pump tilt angle corresponding to the operation amount of the operation member 54 by the operator, and therefore, the required tilt angle requested by the operator is used. Becomes the pump tilt angle control signal corresponding to.

Here, the required tilt angle comparing means 21 is configured such that the second control signal F②_ 2 from the operating member corresponding tilt angle setting means 11 is a predetermined value F 2 a set by the predetermined value setting means 23. If it is determined that the value is larger than 1 low (F②—2> F 2 all ow), the result of the determination is output to the minimum signal output means 22 while the predetermined value set by the predetermined value setting means 23 If it is determined that F 2 a 1 l ow is larger than the second control signal F②—2 from the tilting angle setting means 11 corresponding to the operation member 1 (F②—2 <F 2 all ow), the determination result Is output to the required tilt angle output means 24.

As described above, when the second control signal F② — 2 corresponding to the operator's required tilt angle is equal to or less than the predetermined value F 2 al 1 ow, the second control signal F 2 — 2 regardless of the first control signal F① — 2 The second control signal F②-2 is selected so that the second control signal F を -2 is switched to the pump tilt for the speed control of the hydraulic actuator 106, 109 L, 110. Speed control signal as angle control signal Pump tilt angle (pump flow rate) control as F 2 1 e Ver By doing so, it is possible to suppress a change in the working machine speed (working speed) due to the pump control due to the load fluctuation in the fine operation range. In other words, the second control signal F②_2 based on the operation member operation amount is independent of the fluctuation of the load pressure of the work machine (hydraulic factory), and if the operation member operation amount is constant, the load W fluctuates. Since the pump tilt angle control is performed using the second control signal F②−2 as shown in FIG. 7 (d), the work implement speed (pump The flow rate and pump tilt angle) can be kept constant, and changes in the working machine speed (work speed) caused by pump tilt angle control due to load fluctuations in the fine operation range can be suppressed. Note that, in FIG. 7 (d), the broken line indicates the work machine speed with respect to the load W when the pump tilt angle control is performed using the predetermined value F 2 a 11 ow as the pump tilt angle control signal.

By the way, the predetermined value setting means 23 calculates the allowable maximum horsepower characteristic (horsepower limit allowable value) W2 of the pump displacement angle (pump flow rate) as shown in FIG. The set value F2a11ow is set as a value corresponding to an arbitrary pump tilt angle (predetermined tilt angle) equal to or less than the pump allowable tilt angle (pump allowable flow rate) F2w. The predetermined value F2a11ow is set in advance.

Here, the pump allowable tilt angle (pump allowable flow rate) F 2 w is obtained by the following equation.

F 2 w = W 2 ÷ P m a X

As described above, the predetermined value F 2 a 1 1 ow is set as a value corresponding to an arbitrary pump tilt angle equal to or smaller than the allowable pump tilt angle F 2 w in the fine operation range. This is to suppress the change in work implement speed due to the pump control due to the load fluctuation.

The setting of the predetermined value F2a11ow is not limited to this, and can be arbitrarily set according to the characteristics of various working machines (tools). The minimum signal output means 22 is the minimum control signal from the minimum signal selection means 20.

Fmin is output to the minimum value selecting means 14 in accordance with the determination result by the required tilt angle comparing means 21. That is, the minimum signal output means 22 allows the output of the minimum control signal Fmin from the minimum signal selection means 20 to the minimum value selection means 14 according to the determination result by the required tilt angle comparison means 21. is there.

For this reason, the minimum signal output means 22 supplies the second control signal F②_ 2 based on the operation member operation amount by the required tilt angle comparison means 21 to be larger than the predetermined value F 2 a 11 ow (F② — 2> F 2 all ow), the judgment result is input. When this signal is input, the minimum control signal Fm from the minimum signal selection means 20 is input. in is output to the minimum value selection means 14 as a speed-related control signal F 21 ever for speed control in the evening.

The required displacement angle output means 24 determines that the predetermined value F 2 a 1 ow by the required displacement angle comparison means 21 is larger than the second control signal F−2 based on the operation member operation amount (F−2 <F 2 all ow), the judgment result is input, and the second control signal F-2 based on the operation member operation amount is responded to the speed control for the speed control of the actuator. The control signal is output to the minimum value selecting means 14 as a control signal F21 eVer. The allowable horsepower corresponding tilt angle setting means 13 is used as a pump tilt angle control signal for controlling the tilt angle of the second hydraulic pump 52, as an allowable horsepower corresponding control signal F2po based on the allowable horsepower limit. Wer and the control signal The signal F 2 power is output to the minimum value selecting means 14 described later. Here, the allowable horsepower limit-based control signal F 2 power is an upper limit pump tilt angle control signal that is limited according to the allowable horsepower of the engine 50 that drives the second hydraulic pump 52. . In other words, the allowable horsepower corresponding control signal F2power based on the allowable horsepower limit is set to the second corresponding to the speed corresponding control signal F2 1 eVer selected by the speed corresponding pump tilt angle setting means 12. When the pump tilt angle of the hydraulic pump 52 is controlled, the pump tilt angle (pump flow rate) is controlled so that the load W applied to the engine 50 that drives the second hydraulic pump 52 does not exceed the allowable horsepower of the engine 50. This is a pump tilt angle control signal for the purpose.

Therefore, as shown in FIG. 8, the allowable horsepower corresponding tilt angle setting means 13 stores an allowable horsepower preset based on the engine horsepower of the engine 50 that drives the second hydraulic pump 52. The vehicle includes a horsepower storage unit 8A and an allowable horsepower tilt angle calculation unit 8B. The allowable horsepower tilt angle calculation unit 8B includes a pump discharge pressure signal detected by the pressure sensor 73. Is entered.

Based on the allowable horsepower W2 from the pump allowable horsepower storage unit 8A and the pump discharge pressure P2 from the pressure sensor 73, the allowable horsepower corresponding tilt angle calculation unit 8B The horsepower control signal (allowable flow control signal) F2power is calculated by the following equation.

F 2 p owe r = W2 ÷ P 2

The allowable horsepower limit-based control signal F2power calculated in this way is based on the allowable horsepower limit-based control signal F2power and the pump discharge pressure as shown in Fig. 8. It is represented as a characteristic diagram that associates P2 with P2. Note that, in the characteristic diagram shown in FIG. 8, the straight line indicated by the symbol A indicates the maximum tilt angle (maximum discharge flow rate) of the pump. The minimum value selecting means 14 is set by the speed corresponding control signal F 2 1 e Ver set by the speed corresponding pump tilt angle setting means 12 and the allowable horsepower corresponding tilt angle setting means 13. By comparing with the allowable horsepower control signal F 2 power, a control signal that reduces the pump tilt angle (a control signal that reduces the pump flow rate) is selected, and this is selected as the final pump tilt angle control signal F. This is set as p 2 and output to the second hydraulic pump 52.

Here, the description has been made assuming that the pump flow rate and the pump tilt angle correspond to each other. However, the conversion of the pump flow rate and the pump tilt angle is detected by the engine speed sensor (engine speed detecting means) 71. This is performed by the controller 1 based on the engine speed to be performed.

Since the control device of the construction machine according to the present embodiment is configured as described above, the control method of the pump tilt angle (pump flow rate) by this control device is performed as follows.

First, the tilt angle setting means 5 corresponding to the bypass pressure of the first hydraulic pump tilt angle control means 3 is connected to the oil passages (hydraulic oil supply / discharge passage, hydraulic oil supply passage) 6 1 of the first circuit unit 55. A detection signal of the operating oil pressure detected by the pressure sensor 74 as bypass pressure detecting means disposed downstream of the control valves 57 to 60 is read. Similarly, the tilt angle setting means 10 corresponding to the bypass pressure of the second hydraulic pump tilt angle control means 4 is connected to the oil passage (hydraulic oil supply / discharge passage, hydraulic oil supply passage) of the second circuit portion 56. The control signal of the hydraulic oil detected by the pressure sensor 75 as the bypass pressure detecting means disposed downstream of each of the control valves 62 to 65 is read. These steps are called hydraulic oil pressure detection steps. Next, the tilt angle setting means 5 corresponding to the bypass pressure of the first hydraulic pump tilt angle control means 3 adjusts the pump flow rate (pump tilt angle) based on the characteristic substantially inversely proportional to the flow rate of the hydraulic oil. First control signal for controlling (pump tilt angle control signal) Set F-1. Similarly, the second hydraulic pump tilt angle control means The fourth tilt angle setting means 10 corresponding to the bypass pressure is provided with a first control signal (pump tilt angle) for controlling the pump flow rate (pump tilt angle) based on a characteristic inversely proportional to the hydraulic oil flow rate. Angle control signal) Set F①_2. These steps are called a first control signal setting step.

On the other hand, the operation member signal processing means 2 reads an electric signal corresponding to the operation amount of each operation member 54, and the operation member signal processing means 2 controls each control valve 5 based on the electric signal from each operation member 54. Set the travel distance of 7 to 60 and 62 to 65.

Next, the operation member corresponding tilt angle setting means 6 of the first hydraulic pump tilt angle control means 3 corresponds to the movement amount of each of the control valves 57 to 60 set by the operation member signal processing means 2. Set a second control signal (pump tilt angle control signal) F-1 for controlling the pump flow rate based on a characteristic that is substantially directly proportional to the operation amount of the operation member based on the control signal. Similarly, the tilt angle setting means 11 corresponding to the operation member of the second hydraulic pump tilt angle control means 4 corresponds to the movement amount of each control valve 62 to 65 set by the operation member signal processing means 2. Set a second control signal (pump tilt angle control signal) F②-2 for controlling the pump flow rate based on a characteristic that is substantially directly proportional to the operation amount of the operation member based on the control signal to be performed. These steps are called a second control signal setting step.

Then, the tilt control angle setting means 7 corresponding to the speed control of the first hydraulic pump tilt angle control means 3 outputs the first control signal F-1 and the second control signal set in the first control signal setting step. One of the second control signals F②-1 set in the setting step is selected, and within the allowable horsepower range, the hydraulic pump 51 is tilted based on the selected control signal. Controls the angle (pump flow). Similarly, the speed control-compatible tilt angle setting means 12 of the second hydraulic pump tilt angle control means 4 controls the first control signal F−2 and the second control signal F−2 set in the first control signal setting step. Set in control signal setting step The selected second control signal F②-2 is selected, and within the allowable horsepower range, the pump tilt angle (pump flow rate) of the hydraulic pump 52 based on the selected control signal is selected. Control. These steps are called pump flow control steps.

Specifically, in the pump flow control step, the first control signal F① _ 1 (F

Select the control signal that reduces the pump flow rate from ①- 2) and the second control signal F-1 (F-1).

Therefore, according to the control device and the control method thereof of the present construction machine, the pressure of the hydraulic oil downstream of the control valves 57 to 60 and 62 to 65 of the hydraulic oil supply / discharge passages 61 b and 61 c Is detected by the pressure sensor 74, and the pump tilt angles (pump flow rate) of the hydraulic pumps 51 and 52 are determined based on a characteristic substantially inversely proportional to the bypass flow rate corresponding to the pressure detected by the pressure sensor 74. ) Of the hydraulic pumps 51 and 52 based on the first control signals F①-1, F①_2 and the characteristics that are substantially directly proportional to the operation amounts of the operation members 54. The second control signal is used to control the discharge flow rate of hydraulic oil from the hydraulic pumps 51 and 52 by selecting one of the control signals F②-1 and F②-2. Positive flow control and negative flow control according to the operator's preference. Can be divided have used the Control is advantageous cormorants have to be able to improve the driving feeling.

In addition, by selectively using positive flow control and negative flow control depending on the work such as excavation work and suspension work, the disadvantages of each pump tilt angle control can be compensated by other controls. There are advantages. In other words, for example, when the operator intends to perform work at a fixed work machine speed, or in a hanging work (intermediate operation area or fine operation area of the operation member), by selecting the positive flow control, Hydraulic factories, which are disadvantages of negative flow control 105-107, 109R, 109L, 110 Hydraulic factories 105- It is possible to suppress a sudden increase in the operating bead of 107, 109 R, 109 L, 110 and a hunting phenomenon caused by this.

For example, when performing a boom-up fine operation and a stick-art fine operation at the same time to lift a suspended load suspended at the tip of the stick 104, the stick 104 rotates in the direction d in FIG. Therefore, since the load application point approaches the center of rotation, the load acting on the bump cylinder 105 and the stake cylinder 106 decreases.However, by selecting positive flow control in such work, Thus, it is possible to suppress a sudden increase in the working speed of the cylinder 105 and the stick cylinder 105 and a reduction in hunting due to the increase in the working speed.

Conversely, for example, as the stick 104 rotates in the direction C in FIG. 9, the load acting point moves away from the center of rotation, so that the load acting on the boom cylinder 105 and the stick cylinder 106 increases. However, by selecting the positive mouth control in such a work, the working speed of the boom cylinder 105 and the stick cylinder 105 is reduced, and the working conditions during the lifting work (that is, operating members) It is possible to prevent the operation of the boom 103 0 stick 104 from being stopped due to the operation amount or the magnitude of the load).

On the other hand, for example, selecting negative flow control in excavation work, etc., will result in a hydraulic actuator that cannot be obtained with positive flow control. As the load increases, hydraulic actuators 105-107, 109 R, 109 There is an advantage that load-sensitive filling by reducing the operating speed of L, 110 can be ensured. For example, when excavation work is performed by performing stick-in operation using the operation member 54 as an intermediate operation amount, if the load increases due to contact with an underground object (for example, a pipe), the pump flow rate is reduced. Acts to reduce, which will reduce stick-in speed. Thus, there is an advantageous aspect that the operator can interrupt or correct the stick-in operation by sensing the change in the stick-in speed.

As a result, the intended operation of the operator can be performed, which is preferable in terms of operability. Also, it is possible to suppress a sudden change in the operating speed of the working machine, which is also preferable in terms of safety.

Further, a control signal for decreasing the pump flow rate is selected from the first control signal F①-1 and F①-2 and the second control signal F②-1 and F②-2, and the control signal from the hydraulic pumps 51 and 52 is selected. In order to control the hydraulic oil discharge flow, it takes about 105 to 107, 109R, 109L, 110H for the hydraulic actuators depending on the work such as excavation work and lifting work. Although the load fluctuates, there is an advantage that the positive flow control and the negative flow control can be automatically switched according to the fluctuation of the load. Further, the first control signals F①−1, F①_2 and the second control signals F②_1, F②_2 are compared with each other, and the first control signals F①−1, F②−2 and the second control signal F①−1, F②_2 are compared with each other. Since the control signal that reduces the pump flow rate is selected from the signal F 2-1 and F-2, there is also an advantage that switching between positive flow control and negative flow control can be performed with a simple configuration.

Further, when the second control signals F②-1 and F②-2 are smaller than a predetermined value F 1 a 1 low (F 2 a 1 low), the second control signals F②-1 and F②

-2 to control the discharge flow rate of hydraulic oil from hydraulic pumps 51 and 52 Therefore, when the pump flow rate requested by the operator is smaller than the predetermined pump flow rate, the pump flow rate is controlled based on a characteristic that is substantially directly proportional to the operation amount of the operation member 54. Suppress changes in the operating speed of hydraulic actuators 105 to 107, 109R, 109L, 110H due to load fluctuations in the fine operation area where the operating member 54 is finely operated. There is also the advantage of being able to do this.

Further, since the first control signal F①_1, F①2 and the second control signal F②-1, F②1-2 are selectively used by the software of the controller 1, Another advantage is that it can easily respond to special requirements such as operating preferences and operation of special tools (e.g., hammer, grapple, etc.) without changing hardware such as control valves and pumps.

In the above-described embodiment, the first control signal (negative flow control) inversely proportional to the bypass flow rate and the operation member operation amount are directly proportional to the first control signal (negative flow control) by the minimum signal selection means 20 of the speed control corresponding tilt angle setting means 7. Although the smaller control signal is selected from the second control signal (positive flow control), the control signal selection method is not limited to this, and the operator's preference and special tool ( In order to respond to the operation of the hammer, the grapple, etc., for example, a selection switch that can be operated by the operator is provided. By operating this selection switch, only the first control signal inversely proportional to the bypass flow rate is provided. Using the pump tilt angle control (only for negative flow control) and the second control signal that is directly proportional to the operation amount of the operating member. May be to use a configuration can be selected and a pump tilting angle control (positive flow control only).

Further, in the above-described embodiment, the tilt angle setting means 7 corresponding to the speed control sets the pump tilt angle control signal F mi set using the minimum signal selecting means 20. n and the pump tilt angle control signal F② _ 1 (F②2) set using the tilt angle setting means 6 corresponding to the operation member. The selection is made based on the determination result by the comparing means 21, but is not limited to this, and the pump tilt angle control signal F min set by using the minimum signal selecting means 20 and the operation The operator selects whether to use any one of the pump tilt angle control signals F ②-1 (F ②-2) set using the member corresponding tilt angle setting means 6. It is also possible to perform each required operation.

For example, it is determined whether or not the pump tilt angle (required tilt angle) set based on the operation amount of the operation member by the operator is smaller than a predetermined value F1a1low (F2a1low). Therefore, instead of the required tilt angle comparing means 21 which determines the operation requested by the operator, the operator makes a request based on an electric signal from each operation member according to the operation of each operation member by the operator. A request work determining means for determining the work; a pump tilt angle control signal set by using the minimum signal selecting means based on the determination result of the required work determining means; and a tilt angle corresponding to the operation member. A selection may be made as to which of the pump tilt angle control signals set using the setting means 6 is to be used.

In this case, when stick-in or bucket-in performed mainly during excavation work is performed, the required work determination means determines that the work is excavation work, and the minimum signal selection means 20 is used based on the determination result. In addition to setting the pump tilt angle (setting the pump tilt angle based on the characteristics shown in Fig. 7 (c)), if the boom-up and stick-out performed during the lifting work are performed, the required work determination means Is determined to be a lifting operation, etc., and based on the result of this determination, setting of the pump tilt angle using the required tilt angle comparing means 21 (the pump tilt angle based on the characteristics shown in FIG. Settings]. The required work determination means is based on signals from a plurality of work mode switches such as a truck loading mode (boom priority mode), a trenching mode (swing priority mode), a leveling mode, and a tamping mode. Operet — It may be configured to determine the work that Evening is requesting. Industrial applicability

INDUSTRIAL APPLICABILITY As described above, the control device and the control method for a construction machine of the present invention are useful for a construction machine (for example, a hydraulic shovel) that supplies hydraulic oil from a hydraulic pump to a hydraulic machine for driving a work machine. Particularly, depending on the flow rate of the hydraulic oil supplied to the hydraulic actuator, the operating speed of the hydraulic actuator is rapidly increased, and this is suitable for a construction machine in which a hunting phenomenon occurs due to this. I have.

Claims

The scope of the claims

1. An operation member (54) that is operated by an operator to output an electric signal;

Hydraulic pumps (51), (52) that discharge hydraulic oil in the tank, and hydraulic actuators (105) to (107), (1) that are driven by hydraulic oil discharged by the hydraulic pumps 09 R), (1 09 L)

Hydraulic oil supply passages (61a) and (66a) for supplying hydraulic oil to the hydraulic actuator;

Control valves (57) to (60), (62) to (65) which are interposed in the hydraulic oil supply passage and control the supply of hydraulic oil to the hydraulic actuator;

A control device for a construction machine, comprising: bypass passages (61b) and (66c) for returning hydraulic oil not supplied to the hydraulic actuator through the control valve to the tank.

Pump flow control means for controlling the discharge flow rate of hydraulic oil from the hydraulic pump

(3), (4)

A first control signal F①-1 (F①-2) for controlling the pump flow rate based on a characteristic substantially inversely proportional to a flow rate of the hydraulic oil in the bypass passage, and the operating member; The second control signal F②_ 1 (F②-2) for controlling the pump flow rate based on the characteristic substantially directly proportional to the manipulated variable of A control device for a construction machine, wherein the control device is configured to control a discharge flow rate.

2. The pump flow rate control means (3), (4) controls the pump flow rate of the first control signal F①-1 (F①-2) and the second control signal F②_1 (F②-2). Select the control signal to be reduced and select the hydraulic pump (5 1), (5 2) 2. The control device for a construction machine according to claim 1, wherein the control device is configured to control a discharge flow rate of the hydraulic oil.

3. The pump flow rate control means (3), (4) selects the second control signal when the second control signal F②_1 (F②-2) is smaller than a predetermined value, and selects the hydraulic pressure 2. The control device for a construction machine according to claim 1, wherein the control device is configured to control a discharge flow rate of hydraulic oil from the pumps (51) and (52).

4. The pump flow control means (3), (4) outputs the first control signal F①-1 (F ①) when the second control signal F②_1 (F②-2) is larger than a predetermined value. _ 2) and the control signal for reducing the pump flow rate among the second control signals, while selecting the second control signal when the second control signal is equal to or less than a predetermined value, and selecting the hydraulic pump The control device for a construction machine according to claim 1, wherein the control device is configured to control a discharge flow rate of hydraulic oil from (51), (52).

5. An operating member (54) operated by an operator to output an electric signal;

Hydraulic pumps (51), (52) for discharging hydraulic oil in the tank, and hydraulic actuators (105) to (107), (107) driven by hydraulic oil discharged from the hydraulic pumps 1 09 R), (1 09 L)

Hydraulic oil supply passages (61a), (66a) for supplying hydraulic oil to the hydraulic actuator;

Control valves (57) to (60), (62) to (65) which are interposed in the hydraulic oil supply passage and control the supply of hydraulic oil to the hydraulic actuator; A control method for a construction machine comprising: bypass passages (61b) and (66c) for returning hydraulic oil not supplied to the hydraulic actuator through the control valve to the tank;

Detecting the flow rate of the hydraulic oil in the bypass passage, and setting a first control signal F① 1 (F①-2) for controlling the pump flow rate based on characteristics substantially inversely proportional to the flow rate of the hydraulic oil A first control signal setting step of

A second control signal F②-1 (F②-2) for detecting an electrical signal from the operation member and controlling a pump flow rate based on a characteristic substantially directly proportional to the operation amount of the operation member. A control signal setting step of

One of the first control signal set in the first control signal setting step and the second control signal set in the second control signal setting step is selected, and the control signal is selected from the hydraulic pump. And a pump flow control step of controlling a discharge flow rate of the hydraulic oil.

6. In the pump flow rate control step, a control signal for reducing the pump flow rate is selected from the first control signal F①-1 (F①-2) and the second control signal F②-1 (F②-2). 6. The method for controlling a construction machine according to claim 5, wherein:

7. In the pump flow rate control step, the second control signal is selected when the second control signal F②_1 (F②-2) is smaller than a predetermined value. Item 6. The control method for a construction machine according to Item 5.

8. In the pump flow control step, if the second control signal F②-1 (F②-2) is larger than a predetermined value, the first control signal F①-1 (F①-2) And selecting a control signal that reduces the pump flow rate from the second control signals, and selecting the second control signal when the second control signal is equal to or less than a predetermined value. 6. The control method for a construction machine according to claim 5, wherein