JPH08333778A - Turning circuit for construction machine - Google Patents

Abstract

PURPOSE: To facilitate work by communicating pressure-up operating ports of two-stage relief valves for a turning motor with a pilot oil pressure source through a solenoid change-over valve, and switching the solenoid change-over valve into a relief pressure-down oil passage position when a boom and the like reach required angles. CONSTITUTION: Required boom-up angle and arm pull-in angle are prestored in a controller 38. Pressure-up operating ports of two-stage relief valves 26L, 26R are communicated with a pilot oil pressure source 42 for leading out pilot pressure acting upon the pressure-up operating ports 41L, 41R, through a solenoid change-over valve 28. When both boom-up angle and arm pull-in angle reach the specified angles, detection signals from potentiometers 24, 25 are judged by the controller 38. A change-over command signal is then outputted from the controller 38 to a solenoid 43 of the solenoid change-over valve 28 so as to switch the solenoid change-over valve 28 into a relief pressure-down setting oil passage position (b). Smooth turning start can therefore be performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a swing circuit for an upper swing type construction machine, a working vehicle and the like.

[0002]

2. Description of the Related Art FIG. 5 is a circuit diagram of a swing motor described in Japanese Utility Model Publication No. 3-41203. In the swing circuit of the embodiment of the related art shown in FIG. 5, when the swing hydraulic remote control valve 2 is operated when the swing motor 1 starts to operate, the pilot secondary pressure derived from the swing hydraulic remote control valve 2 is a relief valve. 3 _L and 3 _R boosting operation ports 4 respectively
It acts on _L and 4 _R, and the relief set pressures of the relief valves 3 _L and 3 _R are set to high pressure. As a result, the starting torque of the turning motor 1 is increased, and good acceleration performance at the time of turning start can be exhibited. When stopping the swing of the upper swing body, the swing hydraulic remote control valve is returned to the neutral position. The secondary pilot pressure is the above-mentioned boosting operation port 4
_L, 4 since not act on the _R, the relief valve 3 _L, 3 _R
The relief set pressure of changes to low pressure. As a result, the braking force acting on the turning motor 1 does not act suddenly. That is, since the braking force of the swing motor 1 flexibly corresponds to the inertial force of the upper swing body, smooth stop is performed.

[0003]

FIG. 6 is a side view showing a state of the work attachment 7 mounted on the upper swing body 6 of the hydraulic excavator 5. The work attachment 7 is configured by sequentially connecting a boom 8, an arm 9, and a bucket 10 which is a work tool. When the boom 8 is being lowered and the arm 9 is being pushed out as shown by the phantom line in FIG. 6, the arm 9 is moved from the swing center 0-0 of the upper swing body 6.
The working radius R to the tip portion becomes long, and the inertial mass of the upper swing body 6 at that time is large. However, the rotation starting force of the turning motor 11 is set so that the turning start can be performed even in the above case. However, as shown by the solid line in FIG. 6, when the boom 8 is being raised and the arm 9 is being pulled in, the working radius r from the swing center 0-0 of the upper swing body 6 to the tip of the arm 9 is short, and At that time, the inertial mass of the upper swing body 6 becomes small. Therefore, in the case of the above-mentioned state, the shock of the swing start of the upper swing body 6 is large due to the sufficient rotation start force of the swing motor 11,
It hindered the driver's turning feeling. The present invention
An object of the present invention is to provide a turning circuit that can solve the above problems.

[0004]

According to the present invention, a work attachment in which a boom, an arm, and a work tool are sequentially connected so as to be rotatable in the front-rear direction is attached to the front portion of an upper swing body, and the boom and arm postures are detected. In a construction machine equipped with means, the required boom raising angle and arm retracting angle are stored in the controller in advance, and the boosting operation of the two-stage relief valve that can set up / down pressure for the swing motor mounted on the upper swing body Port and the pilot oil pressure source that derives the pilot pressure that acts on the boosting operation port are connected via an electromagnetic switching valve, and when the boom raising angle and arm retracting angle both reach the above required angles. , The controller detects the detection signals from the boom and arm posture detection means, and Allowed output 換指 command signal, and to switch the electromagnetic switching valve to the relief buck setting fluid passage position.

Further, according to the present invention, a work attachment in which a boom, an arm, and a work tool are sequentially connected to each other so as to be rotatable in the front-rear direction is attached to the front portion of the upper swing body, and a boom and arm attitude detecting means is provided. The detection signals from the boom and arm attitude detecting means are input to a controller equipped on the upper swing body, and the pilot secondary pressure derived from the swing hydraulic remote control valve is supplied to the left and right of the swing motor control pilot switching valve. In the swing circuit of the construction machine in which the swing motor is rotated via the swing motor control pilot switching valve by operating the swing hydraulic remote control valve. It is equipped with a swing pilot pressure detection means to detect the pressure and also for swing motor control. An electromagnetic proportional pressure reducing valve is installed in each pilot circuit that connects the pilot ports on the left and right of the Ylot switching valve and the hydraulic remote control valve for turning.The controller controls the turning based on the detection signals from the boom and arm posture detecting means. The working radius from the center of swing of the body to the arm tip is calculated moment by moment, and the current value according to the calculated working radius value is output to the solenoid proportional pressure reducing valve, and the swing motor control pilot switching valve By reducing the pilot secondary pressure to be applied to the pilot port of, the switching speed and stroke amount of the spool in the swing motor control pilot switching valve are reduced.

[0006]

[Operation] First, the boom raising angle is the predetermined boom raising angle θ.
_{When the} arm retracting angle is smaller than _U and the arm retracting angle is larger than a predetermined arm retracting angle α _U , the controller makes a determination process based on the detection signal from the boom and arm attitude detecting means, and does not output the switching command signal to the electromagnetic switching valve. Since the electromagnetic switching valve is in the pilot pressure conducting oil passage position, the pilot pressure acts on the boosting operation port of the two-stage relief valve, and maintains the relief set pressure at a high pressure. As a result, in this case, a large starting torque of the swing motor can be exerted. Next, when the boom raising angle reaches the predetermined boom raising angle θ _U and the arm retracting angle reaches the predetermined arm retracting angle α _U , the controller makes a judgment process based on the detection signals from the boom and arm posture detecting means, and A switching command signal is output to the switching valve. The electromagnetic switching valve switches from the pilot pressure conducting oil passage position to the relief pressure setting oil passage position. Since the pilot pressure does not act on the boosting operation port of the two-stage relief valve, the relief set pressure of the two-stage relief valve is set to a low pressure.
Therefore, in the above case, the starting torque of the turning motor is held low, and the shock of sudden acceleration at the time of starting the turning can be reduced.

Further, according to the present invention, the detection signals from the boom and arm attitude detecting means are input to the controller every moment during the work of the construction machine. Based on the detection signal, the controller calculates the working radius from the swing center of the upper swing body to the arm tip. In this case, when the turning hydraulic remote control valve is operated, the detection signal from the turning pilot pressure detecting means is input to the controller. The controller determines from the detection signal and the calculated work radius value,
A current value corresponding to the working radius value is output to the electromagnetic proportional pressure reducing valve. That is, when the working radius value is large, the degree of reduction of the pilot secondary pressure by the electromagnetic proportional pressure reducing valve is reduced, and the pilot secondary pressure is reduced to a lower pressure as the working radius value becomes smaller. Therefore, when the boom hydraulic angle θ _U is large and the arm retracted angle α _U is small, operating the turning hydraulic remote control valve
The pilot secondary pressure derived from the turning hydraulic remote control valve is reduced and acts on the pilot port of the turning motor control pilot switching valve. The spool in the swing motor control pilot switching valve moves at a moderate switching speed and a distance shorter than a predetermined stroke amount. The pressure oil from the main pump is supplied to the swing motor through the swing motor control pilot switching valve, but some of the circulating pressure oil bleeds out into the tank communication oil passage because the spool does not make a full stroke. . Therefore, the shock of abrupt acceleration at the time of turning start can be reduced according to the state where the working radius of the arm tip portion becomes small.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a side view of a hydraulic excavator having a swing circuit according to the present invention. In the figure, 12 is an upper swing body of a hydraulic excavator, 13 is a swing motor mounted inside the upper swing body 12, 14 is a work attachment mounted on the upper swing body 12, 15 is a boom of the work attachment 14, 16 is an arm, 17 is a bucket as a work tool, 1
8 is a boom cylinder, 19 is an arm cylinder, 20 is a bucket cylinder, 21 is a pin coupling part that connects the base end of the boom 15 and a boom mounting bracket (not shown) of the upper swing body 12, 22 Is a pin coupling part that connects the tip of the boom 15 and the base end of the arm 16, 23 is a pin coupling part that connects the tip of the arm 16 and the base of the bucket 17, 24 and 25 are pin coupling parts 21, Booms, potentiometers that are arm posture detecting means, and boom raising angles (θ) provided on the pin connecting portion 21
And the angle between the straight line connecting 22 and the horizontal line (HL),
The arm pull-in angle (α) is an angle formed by a straight line connecting the pin connecting portions 21 and 22 and a straight line connecting the pin connecting portions 22 and 23.

Next, FIG. 2 is a swing circuit diagram of the present invention.
In the figure, 26 _L and 26 _R are respectively two-stage relief valves which are arranged for the swing motor 13 and which can set up / down pressure, 27 is a swing motor control pilot switching valve, 28 is an electromagnetic switching valve, and 29 _L and 29 _R are Electromagnetic proportional pressure reducing valve, 30,
Reference numeral 31 is a directional switching valve for controlling a plurality of hydraulic actuators (not shown) mounted on the hydraulic excavator, and 32 is an oil tank 33 penetrating the neutral position of each switching valve 30, 31, 27. To the center bypass oil passage, 34 is a main pump, 35 is a pilot pump, 3
6 is a hydraulic remote control valve for turning, 37 _L and 37 _R are pressure switches which are turning pilot pressure detecting means for detecting the pilot secondary pressure for turning derived from the hydraulic remote control valve 36 for turning, respectively, 38 is a controller, 39 _L , 39 _R are left and right pilot ports of the swing motor control pilot switching valve 27. FIG. 3 is a cross-sectional view of essential parts showing the swing motor control pilot switching valve 27 in the swing circuit of FIG. When the spool 40 is in the neutral position as shown in FIG. 3, the pressure oil discharged from the main pump 34 is
From the P port of the swing motor control pilot switching valve 27, the oil flows out to the oil tank 33 through the center bypass oil passage 32. However, when the pilot port 39 _L acts as indicated by the arrow a, the spool 40 moves in the direction of the arrow b, and the oil flowing out toward the center bypass oil passage 32 is squeezed.
At the same time, the oil passage opens from the spool notch C, and the pressure oil flowing into the P port flows in the direction of arrow D.
It is supplied to the swing motor 13 from the A _L port. The return oil from the turning motor 13 flows from the _BL port in the direction of arrow E and is returned to the oil tank 33 from the T port. As a result, the turning motor 13 starts rotating. FIG. 4 is a chart showing the relationship between the spool stroke S of the spool 40 and the spool opening area A in FIG. In the diagram of FIG. 4, a curved virtual line a is an opening state of the oil passage from the P port to the center bypass oil passage 32, a solid line b is an opening state of the oil passage from the P port to the A _L port through the arrow D, and a broken line C is The opening state of the oil passage from the _BL port to the T port via the arrow E is shown.

Next, the construction and operation of the swing circuit according to the first embodiment of the present invention will be described with reference to FIGS. In the present invention,
The required boom raising angle θ _U and arm retracting angle α _U are stored in the controller 38 in advance, and the two-stage relief valve 2
6 _L and 26 _R boosting ports 41 _L and 41, respectively
_R and a pilot hydraulic pressure source 42 for deriving a pilot pressure to act on the boosting operation ports 41 _L and 41 _R are made to communicate with each other through an electromagnetic switching valve 28, and a boom raising angle (θ) and an arm retracting angle (α ) Both reach the above required angles θ _U and α _U , the potentiometer 24
The controller 38 determines the detection signals from the solenoids 25 and 25, and the controller 38 determines the solenoid 4
A switching command signal is output to 3 and the electromagnetic switching valve 28
Is configured to switch to the relief pressure setting oil passage position.

As a function of the swing circuit of the first embodiment, first, the boom raising angle is smaller than a predetermined boom raising angle θ _U (the boom raising angle stored in the controller 38) (for example, the boom raising angle θ shown in FIG. 1). _D ) and the arm retracting angle is larger than a predetermined arm retracting angle α _U (arm retracting angle stored in the controller 38) (for example, arm retracting angle α _D shown in FIG. 1), detection by potentiometers 24 and 25 is performed. Based on the signal, the controller 38 makes a determination process and does not output a switching command signal to the solenoid 43 of the electromagnetic switching valve 28. Since the electromagnetic switching valve 28 is located at the pilot pressure conducting oil passage position, the pilot pressure from the pilot hydraulic pressure source 42 is applied to the pipeline 44, the electromagnetic switching valve 28 position, and the pipelines 45, 46 and 4.
7, the two-stage relief valves 26 _L and 26 _R act on the pressurizing operation ports 41 _L and 41 _R , respectively. As a result, the relief set pressures of the two-stage relief valves 26 _L and 26 _R are maintained at high pressure.
A large starting torque of 3 can be exhibited. Next, when the boom raising angle reaches the predetermined boom raising angle θ _U and the arm retracting angle reaches the predetermined arm retracting angle α _U , the controller 38 makes a determination process based on the detection signals from the potentiometers 24 and 25, and the electromagnetic switching is performed. A switching command signal is output to the solenoid 43 of the valve 28. Since the solenoid 43 is energized, the electromagnetic switching valve 28 moves from the pilot pressure conducting oil passage position to the relief pressure setting oil passage position (this relief pressure setting oil passage position connects the pilot ports 41 _L and 41 _R to the oil tank 33). It is the position of the oil passage to be tightened). Pilot pressure is two-stage relief valve 2
Since it does not act on the boosting operation ports 41 _L and 41 _R of 6 _L and 26 _R, the relief setting pressures of the two-stage relief valves 26 _L and 26 _R are set to low pressure. Therefore, in the above case, the starting torque of the turning motor 13 is held low, and the shock of sudden acceleration at the time of starting the turning can be reduced.

Next, the construction and operation of the turning circuit of the second embodiment of the present invention will be described with reference to FIGS. In the present invention, the pressure switches 37 _L , 37 are used as the turning pilot pressure detecting means for detecting the pilot secondary pressure derived from the turning hydraulic remote control valve 36 when the turning hydraulic remote control valve 36 is operated.
_R is provided, and the swing motor control pilot switching valve 27
(Hereinafter, referred to as turning a pilot selector valve 27) the pilot port 48 of the left and right _L, 48 _R and a pilot circuit for communicating the swing hydraulic remote control valve 36 (pipe 49 _a -4
9 _b -49 _c, and line 50 _a -50 _b -50 refers to _c) in interposed a solenoid proportional pressure reducing valve 29 _L, 29 _R, respectively, the controller 38 potentiometer 24 in the 25
Based on the detection signal from the above, the working radius from the swing center O′-O ′ of the upper swing body 12 (shown in FIG. 1) to the arm tip portion (referred to as the pin coupling portion 23) is momentarily calculated, and the calculation is performed. A current value corresponding to the working radius value is output to the electromagnetic proportional pressure reducing valves 29 _L and 29 _R to reduce the pilot secondary pressure applied to the pilot ports 48 _L and 48 _R of the turning pilot switching valve 27. Due to the above, the switching speed and the stroke amount of the spool 40 (shown in FIG. 3) in the turning pilot switching valve 27 are reduced.

As a function of the turning circuit of the second embodiment, first, the potentiometers 24 and 2 are used when the hydraulic excavator is in operation.
The detection signal from 5 is input to the controller 38 every moment, and on the basis of the detection signal, the controller 38 moves from the swing center O′-O ′ of the upper swing body 12 to the arm tip (pin coupling portion 23) working radius ( Working radius R'shown in FIG.
Or r ') is calculated. In this case, when the turning hydraulic remote control valve 36 is operated, the pressure switch 37 _L or 37
The detection signal from _R is input to the controller 38. The controller 38 determines from the detection signal and the calculated work radius value, and determines the current value corresponding to the work radius value by the solenoid 51 of each of the electromagnetic proportional pressure reducing valves 29 _L and 29 _R.
Output to _L and 51 _R. That is, when the work radius value is large (for example, when the work radius is R '), the degree of pressure reduction of the pilot secondary pressure by the electromagnetic proportional pressure reducing valves 29 _L and 29 _R is reduced to reduce the work radius value (for example, the work radius). The pilot secondary pressure is reduced to a lower pressure. Therefore, when the swing hydraulic remote control valve 36 is operated when the boom raising angle θ _U is large and the arm retracting angle α _U is small (when the working radius r ′ is small), the swing hydraulic remote control valve 36 is operated.
The pilot secondary pressure derived from (the pilot secondary pressure in this case is derived to the side of the pipe 49 _C for convenience of explanation) is reduced by the electromagnetic proportional pressure reducing valve 29 _L and is used for turning. It acts on the pilot port 48 _L of the pilot switching valve 27. Spool 4 in the pilot switching valve 27 for turning
0 (shown in FIG. 3) moves the switching speed gently and by a distance shorter than a predetermined stroke amount (in the case where the pilot secondary pressure is not reduced). As shown in FIG. 3, the pressure oil from the main pump 34 flows from the P port of the swing pilot switching valve 27 in the direction of arrow D and is supplied to the swing motor 13 from the A _L port. Part of the oil bleeds into the center bypass oil passage 32 leading to the oil tank 33 because the spool 40 does not fully stroke. Therefore, the shock of sudden acceleration at the time of turning start can be reduced.

[0014]

According to the swing circuit of the present invention, when the upper swing body is swung and activated during the work of the construction machine, the boom raising angle of the work attachment is set to the predetermined boom raising angle θ _U and the arm retracting angle is set to the predetermined arm. When the retracted angle α _U is reached, the controller makes a determination process based on the detection signals from the boom and arm attitude detection means, and outputs a switching command signal to the electromagnetic switching valve. The electromagnetic switching valve switches from the pilot pressure conducting oil passage position to the relief pressure setting oil passage position. Since the pilot pressure does not act on the boosting operation port of the two-stage relief valve, the relief set pressure of the two-stage relief valve is set to a low pressure. Therefore, in the above case, the starting torque of the turning motor is held low, and the shock of sudden acceleration at the time of starting the turning can be reduced. Further, in the present invention, when the swing start of the upper swing body is performed during the operation of the construction machine, when the work radius value of the arm tip portion of the work attachment is large, the degree of reduction of the pilot secondary pressure by the electromagnetic proportional pressure reducing valve is reduced, The secondary pilot pressure is reduced to a lower pressure as the working radius becomes smaller. Therefore, if the hydraulic remote control valve for turning is operated when the boom raising angle θ _U is large and the arm retracting angle α _U is small, the pilot secondary pressure derived from the hydraulic remote control valve for turning is reduced to control the swing motor. It acts on the pilot port of the pilot switching valve. The spool in the swing motor control pilot switching valve moves at a moderate switching speed and a distance shorter than a predetermined stroke amount. The pressure oil from the main pump is supplied to the swing motor through the swing motor control pilot switching valve, but some of the circulating pressure oil bleeds out into the tank communication oil passage because the spool does not make a full stroke. . Therefore, the shock of abrupt acceleration at the time of turning start can be reduced according to the state where the working radius of the arm tip portion becomes small. Therefore, in the construction machine equipped with the turning circuit of the present invention, smooth turning start can be performed irrespective of the boom raising angle and the arm retracting angle of the work attachment, so that the turning feeling of the driver at the time of turning start becomes comfortable. be able to.

[Brief description of drawings]

FIG. 1 is a side view of a hydraulic excavator having a swing circuit according to the present invention.

FIG. 2 is a swing circuit diagram of the present invention.

FIG. 3 is a cross-sectional view of essential parts showing a swing motor control pilot switching valve.

FIG. 4 is a chart showing a relationship between a spool stroke and a spool opening area of the spool in FIG.

FIG. 5 is a swing circuit diagram of an embodiment of the prior art.

FIG. 6 is a side view showing a state of a work attachment mounted on the hydraulic excavator.

[Explanation of symbols]

1, 11, 13 Slewing motor 2, 36 Slewing hydraulic remote control valve 4 _L , 4 _R , 41 _L , 41 _R Boosting operation port 6, 12 Upper swinging body 7, 14 Work attachment 8, 15 Boom 9, 16 Arm 24 , 25 Potentiometer 26 _L , 26 _R Two-stage relief valve 27 Swing motor control pilot switching valve 28 Electromagnetic switching valve 29 _L , 29 _R Electromagnetic proportional pressure reducing valve 32 Center bypass oil passage 37 _L , 37 _R Pressure switch 38 Controller 40 Spool 42 Pilot hydraulic source

Claims (3)

[Claims] 1. A construction machine equipped with a work attachment in which a boom, an arm, and a work tool are sequentially connected to each other so that the boom, the arm, and the work tool can be sequentially rotated in the front-rear direction, and the boom and the arm posture detecting means are provided. The required boom raising angle and arm retracting angle are stored in the controller in advance, and the booster operation port of the two-stage relief valve that can set up and down pressure for the swing motor mounted on the upper swing structure and its booster operation The pilot hydraulic pressure source that derives the pilot pressure that acts on the port is connected via an electromagnetic switching valve, and when the boom raising angle and arm retracting angle both reach the above required angles, the boom and arm attitude detection means The controller determines the detection signal of, and outputs a switching command signal from the controller to the solenoid switching valve. A swing circuit for a construction machine, wherein a magnetic switching valve is switched to a relief pressure setting oil passage position. 2. A work attachment in which a boom, an arm, and a work tool are sequentially connected to each other so as to be rotatable in the front-rear direction, is attached to the front part of the upper swing body, and the boom and arm are provided with a boom and arm posture detecting means. The detection signal from the attitude detection means is input to the controller equipped on the upper swing body, and the pilot secondary pressure derived from the swing hydraulic remote control valve is supplied to the left and right pilot ports of the pilot switching valve for swing motor control. The rotation pilot secondary pressure is detected in the swing circuit of the construction machine in which the swing motor remote control valve is operated to rotate the swing motor through the swing motor control pilot switching valve. Is equipped with a swing pilot pressure detection means, and a pilot switching valve for swing motor control. An electromagnetic proportional pressure reducing valve is provided in each of the pilot circuits that connect the left and right pilot ports to the swing hydraulic remote control valve, and the controller swings the upper swing body based on the detection signals from the boom and arm posture detection means. The working radius from the center to the arm tip is calculated moment by moment, and a current value according to the calculated working radius value is output to the solenoid proportional pressure reducing valve, and the pilot port of the swing motor control pilot switching valve By reducing the pilot secondary pressure acting on
A swing circuit for a construction machine, wherein a switching speed and a stroke amount of a spool in a swing motor control pilot switching valve are reduced. 3. A swing circuit for a construction machine according to claim 1, further comprising swing pilot pressure detection means for detecting a swing pilot secondary pressure derived from a swing hydraulic remote control valve, and a swing motor. An electromagnetic proportional pressure reducing valve is provided in each of the pilot circuits that connect the left and right pilot ports of the control pilot switching valve and the turning hydraulic remote control valve, and the controller uses the detection signals from the boom and arm posture detecting means to The working radius from the swing center of the upper swing body to the arm tip is calculated moment by moment, and the current value according to the calculated work radius is output to the electromagnetic proportional pressure reducing valve, and the pilot switching for swing motor control is performed. By reducing the pilot secondary pressure acting on the pilot port of the valve, the pilot switching valve for swing motor control A swing circuit for a construction machine, characterized in that the switching speed and stroke amount of the spool are reduced.