KR960004409B1 - Method and apparatus of oil pressure control for a excavator - Google Patents

Abstract

The method and apparatus is for optimally controlling an engine and a hydraulic pump, and automatically forms a flow passage circuit according to the selection of a work mode. The method comprises a step of selecting the work mode; a step of calculating a 1st target of flow rate by choosing a calculation formular and adding the discharge pressure of hydraulic pumps(13,14); a step of calculating a 2nd target of flow rate, and calculating a 2nd target of the flow rate; a step of choosing a minimum value between the two target flow rates, and regulating the tangent of a inclination palte of the hydraulic pumps(13,14); and a step of determining a moving angle of an engine governer lever(34) according to the selected mode.

Description

Hydraulic control method and device of excavator

1 is an explanatory view of a hydraulic system showing an embodiment of the present invention.

2 is a hydraulic pump control system as another embodiment of the present invention.

3 is a system diagram using Posicon pressure as another embodiment of the present invention.

4 is a driving determination apparatus as an embodiment of the present invention.

5 is an engine control flowchart of the present invention.

6 is a flowchart illustrating a first target flow rate calculation of the present invention.

7 is a flowchart illustrating a second target flow rate of the present invention.

8 is a flow chart of a hydraulic pump regulator control of the present invention.

9 is a flowchart illustrating a second target flow rate calculation for improving driving stability of the present invention.

10 is an embodiment of the present invention,

(a) is the first target flow diagram in the standard, stationary, side digging operation mode.

(b) is the first target flow rate diagram in the crane working mode

(c) is the first target flow rate diagram in the heavy operation and the dump operation mode

(d) is the first target flow diagram in the economic working mode.

11 is an embodiment of the present invention.

(a) is the second target flow diagram in the standard work, stop work, side excavation work, heavy work, dump work, and economic work mode.

(b) is the second target flow rate diagram in the crane working mode

* Explanation of symbols for main parts of the drawings

4, 6, 9, 29: solenoid valve 5, 8, 27, 28: proportional control solenoid valve

7: relief valve 10: 1st direction control valve

10a: driving spool (left driving) 10b: turning spool

10c: Boomspool (boom II) 10d: Armspool (arm I)

11, 21: parallel euros 12, 22: variable orifice valve

13, 14: 1st, 2 hydraulic pump 15: steering hydraulic pump

16 engine 17 control device

18: fuel amount adjusting means 19: working mode selection unit

20: second direction control valve 20a: driving spool (space travel)

20c: Boomspool (I) 20d: Armspool (arm II)

20e: Bucket Spool 23: Step motor

24: angle sensor 25, 26: regulator

30, 31: oil pressure sensor 32, 33: negative cone pressure sensor

34: governor lever 37: display unit

38: rotation speed detector 39: turning speed adjusting means

The present invention relates to a hydraulic control method and apparatus of an excavator, and in particular, to distinguish the working mode by working characteristics, and to automatically adjust the engine and hydraulic pump to the optimum state according to the working mode selection, the flow path matching the working characteristics is automatically It is to be formed.

As is well known, excavators are used in various ways, such as excavation and transfer of soil, loading work of soil, lifting of heavy materials, stopping (ground leveling), and requires an experienced operator suitable for performing these various tasks.

However, even for the experienced driver, it is difficult to operate an excavator composed of a plurality of hydraulic operation cylinders in accordance with the working characteristics while appropriately distributing the flow rate to each operation line.

Therefore, in order to increase the work efficiency for each type of excavator and to operate more easily, it is necessary to control the discharge flow rate of the hydraulic pump, which is the energy generating means of the excavator, and to send the discharged hydraulic pressure to the flow path formed reasonably according to the working characteristics. .

The hydraulic pump control method of an excavator is known to control the hydraulic pump regulator mechanically according to the discharge pressure of the hydraulic pump and the load of each operating cylinder.

However, since the pump regulator is controlled only according to the discharge pressure and the load of the pump, this method involves a lot of difficulties in controlling the discharge flow rate of the pump according to the work characteristics or the types thereof.

In addition, the engine control for driving the hydraulic pump is to control the fuel consumption to be controlled entirely by the driver, there is a hassle to control the engine for each work characteristic, that is, the workload.

An object of the present invention for solving the above-mentioned disadvantages of the conventional excavator is to distinguish the working mode by working characteristics, and to ideally control the output of the engine output and the hydraulic pump according to the selection of the working mode. In order to improve the work performance and the convenience of operation operation, the flow path is selectively changed to suit the working characteristics.

Hereinafter, the hydraulic device and the control method of the present invention will be described in detail.

The hydraulic device is composed of at least two variable displacement first and second hydraulic pumps 13 and 14 and one steering hydraulic pump 15 so as to be driven by the engine 16 and connected to the first hydraulic pump 13. The hydraulic pressure discharged from) is distributed to the respective working cylinders through the first direction control valve 10, and at the same time, some hydraulic pressures are formed to act on the relief valve 7, and the second hydraulic pump 14 The hydraulic pressure discharged from the air flow path is formed to act on the relief valve 7 while being distributed to the respective working cylinders through the second direction control valve 20.

In addition, the first direction control valve 10 includes at least a running spool 10a, a swinging spool 10b, a boom spool 10c, an arm spool 10d, and a parallel flow path 11 between the respective spools. The swing spool 10b is positioned upstream to receive a flow rate in preference to the boom spool 10c or the arm spool 10d from the first hydraulic pump 13, and the swing spool 10b. In the parallel flow path 11 between the boom spools 10c, a variable orifice valve 12 capable of varying the passage flow rate is provided.

The orifice valve 12 is connected to a control hydraulic line via the proportional control solenoid valve 5, and the proportional control solenoid valve 5 is configured to operate by receiving an electric signal from the control device 17. The solenoid valve 6 is installed in the boom rising side adjustment hydraulic line of the spool 10c, and the solenoid valve 6 is operated by receiving an electric signal from the control device 17.

In addition, the second directional control valve 20 includes at least a running spool 20a, a bucket spool 20e, a boom spool 20c, an arm spool 20d, and one preliminary spool 20f. A parallel flow path 21 is formed between the spools, and the boom spool 20c is positioned upstream to receive a flow rate preferentially from the second hydraulic pump over the arm spool 20d, and the boom spool 20c and the arm spool ( Between 20d), a variable orifice valve 22 capable of varying the passage flow rate is provided.

And the variable orifice valve 22 is connected to the control hydraulic line via the proportional control solenoid valve (8), the proportional control solenoid valve (8) is configured to operate by receiving an electrical signal from the control device (17) The solenoid valves 4 and 9 are installed at both side hydraulic lines of the arm spool 20d, and are configured to operate by receiving an electric signal from the control device 17.

Meanwhile, the first and second hydraulic pumps 13 and 14 are configured to adjust the inclination of the inclined plate by the regulators 25 and 26 and the proportional control solenoid valves 27 and 28 in the control hydraulic lines of the regulators 25 and 26. ), But is configured to control the flow rate of the control hydraulic line supplied to the regulator (25, 26) by being operated by receiving an electrical signal from the control device (17).

In addition, a hydraulic pressure line for adjusting the relief pressure of the relief valve 7 is connected to a hydraulic pressure line, and on the line, a solenoid valve 29 controlled by the controller 17 is installed so that the hydraulic pressure of the hydraulic pressure line is increased. It is possible to supply or cut off to the hydraulic part of the relief valve 7.

In addition, the hydraulic pressure sensors 30 and 31 for detecting the discharge oil pressure of the first and second hydraulic pumps are installed in the discharge line side hydraulic lines of the first and second hydraulic pumps 13 and 14. The signal is connected to be input to the control device 17, and the negative flow pressure sensors 32 and 33 are installed in the flow path returning to the hydraulic oil tank without being used from the first and second directional control valves 10 and 20. Signals of the negative cone pressure sensors 32 and 33 are connected to be input to the controller 17.

In addition, the governor lever 34 of the engine 16 is connected to be operated by the step motor 23, and the step motor 23 receives the electric signal from the control device 17 to drive the governor lever 34, The rotation angle of the step motor 23 is input to the control unit 17 by being sensed by the angle sensor 24, and the rotation speed of the engine 16 is installed on the rotation axis of the engine 16. It is configured to be detected and input to the control unit 17.

The controller 17 is connected to the fuel amount adjusting means 18, the work mode selector 19 and the revolution speed adjusting means 39 so as to receive a signal, and to the display unit 37 displaying the selected work mode. .

On the other hand, as an embodiment of the present invention, the control device by installing the inclination detector (80, 81) for detecting the inclination of the inclination plate of the hydraulic pump on the regulator (25, 26) of the first, second hydraulic pump (13, 14) The signal is input to (17), and the regulators 25 and 26 form control hydraulic lines on both sides, and install solenoid valves 76, 77, 78 and 79 in parallel to one control hydraulic line. Inclined plate tilt compensation means of the first and second hydraulic pumps electrically connected to the control device (17).

Wherein the work mode selection unit 19 is at least a standard mode (Heavy mode), heavy mode (Heavy mode), dump mode (Dunp Mode), stop mode (Leveling Mode), crane mode (Crane Mode) ), Slope mode (Economy Mode) and side excavation mode.

Reference numerals are 35: boom spool control lever, 36: arm spool control lever, 40: posicon pressure sensor, 41: traveling hydraulic sensor 42, 43: left and right driving lever.

Next, the hydraulic control method of an excavator is demonstrated.

1. Control method of the first and second hydraulic pumps 13 and 14

First target flow calculation stage

When the hydraulic pressure discharged from the first and second hydraulic pumps 13 and 14 is sensed by the hydraulic sensors 30 and 31 and input to the control unit 17, the control unit 17 sums up the hydraulic pressures to select the working mode. The first target flow rate is calculated by substituting the first target flow rate calculation formula determined accordingly.

The flow rate calculation formula calculates the first target flow rate in approximately inverse proportion to the sum hydraulic pressure as shown in FIG.

On the other hand, if the selected work mode is heavy work, dump work, economic work, and side excavation work mode, the rated rotation speed of the engine corresponding to the angle of the governor lever 34 of the engine is calculated and the actual speed of the engine from the speed sensor 38 is calculated. The rotation speed is detected to compare the rated rotation speed with the rotation speed, and the first target flow rate value decreases approximately in proportion to the increase in the rotation speed difference.

In other words, when the rotation speed difference is small when the rotation speed difference is small, the first target flow value decreases when the rotation speed difference is large.

Calculation step of the second target flow

When the oil pressure of the return flow path which is not used from the first and second directional control valves 10 and 20 is sensed by the negative cone pressure sensors 32 and 33 and input to the control device 17, the control device 17 is The second target flow rates of the first and second hydraulic pumps 13 and 14 are calculated by substituting the negative cone pressure into the second target flow rate calculation formula determined according to the operation mode selection.

As shown in FIG. 11, the second target flow rate calculation formula calculates the second target flow rate in inverse proportion to the magnitude of the negative cone pressure, but the increase rate of the target flow rate is slowed at the same time when the selected work mode is the crane work mode. .

On the other hand, in another embodiment of calculating the second target flow rate, as shown in FIG. 3, instead of the negative cone pressure, the control hydraulic pressure supplied to each of the spools of the first and second directional control valves 10 and 20 is the posicon pressure sensor 40 And calculates the second target flow rate approximately in proportion to the posicon hydraulic pressure.

In the above description, the negative pressure (abbreviation of negative control) refers to the hydraulic pressure returned to the hydraulic oil tank without being used for the operation cylinder in the flow rates discharged from the first and second hydraulic pumps 13 and 14, and used for the operation cylinder. As the flow rate increases, the negative cone pressure decreases, and as the use flow rate decreases, the negative cone pressure increases.

In addition, posicon (abbreviation of positive control) pressure means the hydraulic pressure discharged from the control hydraulic pump 15 and acting on a spool via a spool steering lever, and is proportional to the operation amount of a spool steering lever.

Control of the first and second hydraulic pumps 13 and 14

The first target flow rate value commonly applied to the first and second hydraulic pumps 13 and 14 and the second target flow rate values independently determined to the first and second hydraulic pumps 13 and 14 are respectively converted into current values. Then, a smaller value is selected among these current values to determine the final target flow value and used as a drive signal of the proportional control solenoid valves 27 and 28.

The proportional control solenoid valves 27 and 28 control the pressure of the control hydraulic line supplied to the regulators 25 and 26 of the first and second hydraulic pumps 13 and 14 in proportion to the current value.

The regulators 25 and 26 control the discharge flow rate by adjusting the inclination of the inclined plates of the first and second hydraulic pumps 13 and 14, respectively.

Another method of controlling the inclination of the inclined plates of the first and second hydraulic pumps 13 and 14 is the first and second hydraulic pumps 13 and 14 according to the operation of the regulators 25 and 26 as shown in FIG. Detects the inclination of the inclined plate from the detectors 80 and 81 and inputs it to the control unit 17, and the control unit 17 compares the inclination value calculated from the input inclination value with the final target flow value and compares the solenoid valve by the difference. The inclination plate inclination of the first and second hydraulic pumps 13 and 14 is adjusted by supplying or discharging the control hydraulic pressure to the regulators 25 and 26 by means of 76, 77, 78 and 79.

2. Output control method of the engine (16).

When the work mode signal selected from the work mode selection unit 19 is input to the control device 17, the control device 17 selects a moving angle value of the governor lever 34 of the engine 16 determined for each work mode, The moving angle value is converted into an electric signal and transmitted to the driving step motor 23 of the governor lever 34 to drive the governor lever 34.

On the other hand, the control device 17 determines the moving angle of the engine governor lever 34 according to the electric signal provided from the fuel amount adjusting means 18 and compares it with the moving angle of the governor lever 34 determined in the operation mode selection. A small value can be taken and used as a drive signal of the step motor 23.

As the amount of fuel supplied to the engine 16 increases or decreases as the governor lever 34 moves, the rotation speed of the engine 16 also increases or decreases.

In addition, the actual rotation angle (movement angle of the governor lever 34) of the step motor 23 is detected by the angle sensor 24 installed in the step motor 23 and input to the control device 17, and the control device 17 The angle of movement of the governor lever 34 is compensated by comparing with the angle of movement of the governor lever 34 already determined therein.

3. Examples of working modes.

As an embodiment of the present invention will be described with respect to the control method of the engine and the hydraulic pump for each operation mode and the flow path control of the discharge hydraulic pressure as shown in Table 1, 2.

4. Embodiment of the present invention for securing running stability.

As shown in FIG. 4, when the driver manipulates the left or the space hang levers 42 and 43, the hydraulic pressure of the control hydraulic pump 15 acts on the hydraulic pressure portions of the driving spools 10a and 20a, thereby driving the driving spool. Move.

At this time, when the driving hydraulic pressure of the driving levers 42 and 43 and the driving spools 10a and 20a is increased and sensed by the traveling hydraulic pressure sensor 41 and input to the control unit 17, the control unit 17 causes the vehicle to travel. It will be recognized.

Therefore, the controller 17 detects the negative cone pressure and compares it with the allowable decrease rate per unit time already set in the controller 17, and if the decrease rate of the negative cone pressure is larger than the decrease rate set in the controller 17, In other words, when the negative cone pressure drops rapidly, the negative cone pressure is modulated to match the allowable reduction rate per unit time as described above.

By calculating the second target flow rate by the modulated negative cone pressure, the second target flow rate is gradually increased, and thus the discharge flow rate of the pump is also gradually increased, thereby preventing sudden start and acceleration of the vehicle.

On the other hand, during sudden deceleration, if the rate of rise of the negative cone pressure is greater than the allowable rise rate previously set in the control device, the sudden decrease of the vehicle can be prevented by modulating the negative cone pressure to coincide with the allowable rise rate.

As described above, according to the present invention, since the modes are classified according to the working characteristics of the excavator, the engine output and the discharge flow rate of the hydraulic pump can be optimally controlled, and the flow path can be selectively controlled to suit the working characteristics. In addition to contributing to improvement, even inexperienced drivers can operate smoothly.

Claims (18)

The operation mode selection step and the first target flow rate calculation formula are selected according to the selection, and the discharge hydraulic pressures of the first and second hydraulic pumps 13 and 14 are summed and substituted into the first target flow rate calculation formula. The second target flow rate calculation formula is selected according to the step of calculating the flow rate and the operation mode selection, and the negative pressures of the first and second hydraulic pumps 13 and 14 are sensed and substituted into the second target flow rate calculation formula. Computing a second target flow rate of each of the first hydraulic pump 13 and the second hydraulic pump 14, and selecting a smaller value of the first target flow rate and the second target flow rate to determine the first and second hydraulic pumps ( 13 and 14, the inclination of the inclination plate is adjusted, the step of determining the moving angle of the engine governor lever 34 according to the operation mode selection, and the step of moving the engine governor lever 34 according to the moving angle. Hydraulic control method of the excavator characterized in that. The method of claim 1, wherein the moving angle of the engine governor lever (34) is determined by the fuel amount adjusting means (18). 3. The excavator according to claim 1 or 2, wherein the moving angle of the engine governor lever 34 is selected from the angle determined by the operation mode selection and the angle determined by the fuel amount adjusting means 18. Hydraulic control method. 2. The excavator of claim 1, wherein the first target flow rate calculation formula is calculated according to a difference between the rated rotational speed of the engine and the actual rotational speed of the engine determined according to the moving angle of the engine governor lever 34. Hydraulic control method. 2. The excavator of claim 1, wherein the second target flow rate calculation formula when selecting a crane work mode has a minimum target flow rate value larger than that of other work modes, and the second target flow rate increases slowly with decreasing negative pressure. Hydraulic control method. 2. The second target flow rate calculating step of claim 1, wherein the second target flow rate calculation step determines whether or not the vehicle is driven and modulates the rate of increase or decrease of the speed of the negative cone pressure gently when the negative cone pressure drops or rises per unit time. Hydraulic control method of an excavator, characterized in that for calculating. The tilt control step of the first and second hydraulic pumps 13 and 14 converts the first and second target flow values into current values, and selects a smaller current value among these current values to perform proportional control. The first and second hydraulic pumps 13 and 14 are inclined by the regulators 25 and 26, which are used as driving signals of the solenoid valves 27 and 28 and are controlled according to the operation of the proportional control solenoid valves 27 and 28. Hydraulic control method of the excavator, characterized in that the inclination of the adjustable. The method of claim 1, wherein the step of adjusting the inclination of the inclined plate of the first and second hydraulic pumps 13 and 14, the inclination values of the first and second hydraulic pumps 13 and 14 and the inclined plate and the first and second hydraulic pumps ( And a means for comparing the actual movement of the inclined plate regulators (25, 26) of 13 and 14 and compensating for the difference. The flow rate discharged from the first hydraulic pump 13 when the dump operation mode is selected is the swing spool 10b than the other spools located downstream of the swing spool 10b in the first direction control valve 10. And a means for variably controlling the passage flow rate of the parallel flow path (11) so as to be supplied first). 10. The means for varying the passage flow rate of the parallel flow passage (11) according to claim 9, wherein the current value is adjusted by the turning speed adjusting means (39), and the opening area of the proportional control solenoid valve (5) is controlled by this current value. And the opening area of the variable orifice valve (12) is adjusted according to the opening area. The method according to claim 1, wherein when the crane working mode is selected, the allowable discharge pressures of the first and second hydraulic pumps 13 and 14 are increased, and the booms and the arm spools 10c and 10d in the first and second directional control valves 10 and 20. Hydraulic control method of an excavator comprising a means such that only one boom pool and an arm spool each of (20c, 20d) to each other selectively. The discharge flow rate of the second hydraulic pump 14 when the stop operation mode is selected is the boom spool 20c than the other spools located downstream of the boom spool 20c in the second direction control valve 20. Hydraulic control method of an excavator comprising a means for variably controlling the flow rate of the parallel flow path (21) so as to be supplied first. The operation mode selection step and the first target flow rate calculation formula are selected according to the selection, and the discharge hydraulic pressures of the first and second hydraulic pumps 13 and 14 are summed and substituted into the first target flow rate calculation formula. Calculating a flow rate, selecting a second target flow rate calculation formula according to the operation mode selection, detecting a pilot pressure of a control hydraulic line passing through the control lever, and substituting the second target flow rate calculation formula to the second target flow rate calculation formula; Calculating a flow rate, selecting a smaller value among the first and second target flow rates to adjust the inclination of the inclination plate of the first and second hydraulic pumps 13 and 14, and an engine governor lever according to the operation mode selection ( 34) a step of determining the moving angle, and the engine governor lever 34 is moved according to the moving angle of the hydraulic control method of the excavator. In the excavator comprising at least two variable displacement hydraulic pumps and two directional control valves for receiving and supplying the hydraulic oil from the hydraulic pump to distribute and supply the hydraulic oil to each operating cylinder, the hydraulic oil from the first hydraulic pump 13 The first direction control valve 10 is supplied with at least a running, turning, boom, arm spool (10a, 10b, 10c, 10d), and forming a parallel flow path 11 between each spool, The spool 10b is installed at a position where the discharge pressure oil of the first hydraulic pump 13 is first supplied to the boom and the arm spools 10c and 10d, and the parallel flow passage 11 between the turning and boom spools 10b and 10c is provided. ) Is provided with a flow rate adjusting means, the control hydraulic line connected to the hydraulic pressure side of the boom rise side of the boom spool (10c) is provided with a solenoid valve (6) which can block the supply of the hydraulic pressure, the second hydraulic pump (14) At least traveling to the second direction control valve 20 supplied with pressure oil from And a parallel flow path 21 between the respective spools, wherein the boom spool 20c has a second hydraulic pump (20d) rather than the arm spool 20d. The discharge pressure oil of 14) is installed at a position to be supplied first, and a flow rate adjusting means is provided in the parallel flow path 21 between the boom and the arm spools 20c and 20d, and is supplied to both hydraulic parts of the arm spool 20d. The control hydraulic line is provided with a solenoid valve (4, 9) to cut off the supply of the control hydraulic pressure, proportional to the control hydraulic line supplied to the regulators (25, 26) of the first and second hydraulic pumps (13, 14). The control solenoid valves 27 and 28 are installed so that the regulators 25 and 26 can be controlled, and the hydraulic pressure sensors 30 and 31 are provided in the discharge hydraulic lines of the first and second hydraulic pumps 13 and 14. And negative electrode pressure sensors 32 and 33 are installed in a flow path that is unused from the first and two-way control valves 10 and 20 and returns to the hydraulic oil tank. The control unit 17 is a pressure signal detected from the hydraulic pressure sensor 30, 31 and the negative-cone pressure sensors 32, 33 and fuel amount adjusting means 18, the work mode selection unit 19, the turning speed adjustment Wiring so that the electric signal provided from the means 39 can be applied, and the means, the proportional control solenoid valves 27 and 28 and the solenoid valve are provided to control the flow rate of the first and second directional control valves 10 and 20. Hydraulic control device of an excavator, characterized in that configured to provide an electrical signal. The flow rate control means of the parallel flow paths (11, 21) in the first, two-way control valves (10, 20) comprises variable orifice valves (12, 22), wherein the variable orifice valve (12, 22, a proportional control solenoid valve (5, 8) is provided in the control hydraulic line connected to the hydraulic part of the control unit to adjust the opening area of the control hydraulic line according to the electric signal amount of the control unit (17). Hydraulic control device. 15. The hydraulic control device of an excavator according to claim 14, wherein the control device (17) comprises means for determining the moving angle of the engine governor lever (34) according to the operation amount of the fuel amount adjusting means (18). 15. The excavator hydraulic pressure control device according to claim 14, wherein the control device (17) comprises means for adjusting an amount of electric signal applied to the proportional control solenoid valve (5) in accordance with the amount of operation of the swing control means (39). 15. The excavator hydraulic control device according to claim 14, wherein the control device (17) includes a display portion (37) for displaying an optional working mode.