JP2715180B2 - Control device for hydraulic drive machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device for a hydraulic drive machine.

[Conventional technology]

When a warm-up operation is to be performed on a conventional hydraulic drive machine, an operator performs an operation of holding a hydraulic lever that drives the work implement by a predetermined method and operating the operation lever at full stroke. As a result, a pressure loss of the hydraulic oil supplied to the hydraulic actuator occurs, and the hydraulic oil temperature rises.

[Problems to be solved by the invention]

As described above, in the past, when performing a warm-up operation, the operator had to perform an operation of holding the operation lever at the stroke end until the hydraulic oil temperature suitable for the operation was reached. Was causing fatigue.

Moreover, as described above, when the hydraulic actuator is fixed by a predetermined method, the original excavation work or the like cannot be performed by operating the hydraulic actuator until the warm-up operation is completed. For this reason, the working efficiency has been significantly impaired.

Accordingly, an object of the present invention is to provide a device capable of performing a warm-up operation of a hydraulic drive machine without imposing a significant burden on an operator and without impairing work efficiency.

[Means for solving the problem]

Therefore, according to the present invention, there is provided a hydraulic pump driven by an engine, and a first pressure oil supply path communicating the hydraulic pump, an operation valve operated by an operation lever, and a hydraulic actuator, and operating the operation lever. A hydraulic drive machine configured to supply hydraulic oil discharged from the hydraulic pump in accordance with an amount to the hydraulic actuator to drive the hydraulic actuator, wherein the hydraulic pump communicates with the operation valve and the drain tank. A second pressure oil supply path, a variable orifice disposed in the second pressure oil supply path and varying a cross-sectional area of the second pressure oil supply path, and a pressure orifice supplied to the hydraulic actuator. Temperature detection means for detecting a temperature, when the operation valve is in a neutral state, and when the temperature of the pressure oil detected by the temperature detection means is lower than a predetermined temperature, Temperature of the pressure oil is to comprise a variable orifice control means for performing control to reduce the cross-sectional area of the second hydraulic fluid supply path to be equal to or greater than the predetermined temperature.

[Action]

According to the configuration of the first aspect, when the temperature of the pressure oil supplied to the hydraulic actuator is lower than the predetermined temperature and the warm-up operation is not sufficiently performed, the second pump that connects the hydraulic pump, the operation valve, and the drain lance is connected. The variable orifice is controlled so that the cross-sectional area of the second hydraulic supply path is reduced. As a result, pressure loss occurs in the variable orifice, the oil temperature rises, and eventually reaches a predetermined temperature. As described above, since the warm-up operation is automatically performed, the burden on the operator is reduced.

In addition, the variable orifice is controlled only when the operating valve is in the neutral state, and when the operating valve is not in the neutral state, the original excavation work or the like can be performed by operating the hydraulic actuator. The warm-up operation is performed. For this reason, work efficiency is dramatically improved.

〔Example〕

Hereinafter, an embodiment of a control device for a hydraulic drive machine according to the present invention will be described with reference to the drawings.

FIG. 1 shows a configuration of an embodiment apparatus applied to a hydraulic drive machine, for example, a power shovel.

The working machine hydraulic circuit shown in the figure is configured as follows. That is, the variable displacement hydraulic pump 1 is driven by the engine 2, and the discharge flow rate per rotation is changed by changing the tilt angle of the swash plate 1 a by the swash plate driving servo valve 3. The pressure of the discharge-side pipe line of the hydraulic pump 1 and the pressure of the jet sensor orifice 6 are applied to the swash plate driving servo valve 3 as pilot pressure. Valve 3 selects the smaller one of these and swash plate
Tilt 1a.

The discharge pressure oil of the pump 1 passes through a first pressure oil supply path T1 that connects the hydraulic pump 1, the operation valve 4, the cylinder chamber of the hydraulic cylinder 8, and the drain tank 7, and the hydraulic pump 1 and the operation valve 4 And a variable pressure orifice 5, a jet sensor orifice 6, and a second pressure oil supply passage T2 which communicates with the drain tank 7.

The electric operation lever 9 is an operation lever for switching the operation valve 4, and the operation stroke amount of the lever 9 is detected by a lever stroke amount detection sensor 9 a, and a detection signal is applied to a hydraulic device controller 10. The operating valve solenoid 11 is energized in response to a signal applied from the hydraulic device controller 10 to drive the spool of the operating valve 4. Variable orifice 5
Is a variable orifice that varies the cross-sectional area of the pipeline of the second pressure oil supply passage T2, and the cross-sectional area is changed according to a signal applied to the solenoid 5a.

The hydraulic oil temperature sensor 12 is a temperature sensor that is provided at an appropriate position in the hydraulic oil pipeline and detects the temperature of the hydraulic oil supplied to the hydraulic cylinder 8. Can be

The engine 2 is provided with a fuel injection pump 13 and a governor 14. The fuel control lever 14a of the governor 14 is driven by a stepping motor 15, and the drive position of the lever 14a is detected by a potentiometer 16. The slot dial 17 is a dial for setting a target engine speed, and a throttle signal set by the dial 17 is applied to the hydraulic controller 10. The rotation sensor 18 is a sensor that detects the number of rotations of the output shaft of the engine 2, and a rotation signal detected by the sensor 18 is applied to the hydraulic device controller 10 and the governor controller 19.

The governor controller 19 controls the engine speed detected by the rotation sensor 18, the throttle signal of the slot dial 17 applied from the hydraulic device controller 10, that is, the target speed of the engine 2, and the drive position of the governor 14 detected by the potentiometer 16. Based on the above, the drive position of the governor 14 is controlled so that the output torque of the engine 2 moves along a predetermined regulation line. It should be noted that such a governor control technique is well-known and has no direct relation to the gist of the present application, so that further detailed description will be avoided.

The hydraulic pump discharge oil pressure sensor 20 is a pressure sensor that is provided in the pipeline on the discharge side of the hydraulic pump 1 and detects the pressure of the discharge pressure oil of the hydraulic pump 1. Can be Further, the mode changeover switch 21 is a switch for selecting a work mode as described later, and a signal indicating the selected work mode is applied to the hydraulic device controller 10.

Hereinafter, in the hydraulic device controller 10, the following first to third
Is performed.

1) First control (warm-up operation control) This first control automatically and quickly shifts the temperature of the pressure oil supplied to the hydraulic cylinder 8 shown in FIG. 1 to a temperature suitable for work. This is the control to make it happen.

FIGS. 2 and 3 show flowcharts of the first control.

As shown in FIG. 2, first, a detection signal t of the working oil temperature sensor 12 is taken in (step 101), and it is determined whether or not the detected temperature t is equal to or higher than a predetermined temperature Tset. Here, it is assumed that the predetermined temperature Tset is set as the temperature of the pressure oil suitable for the operation of the hydraulic drive machine (step 102).
If the determination result of step 102 is NO, that is, if it is determined that the temperature t of the pressure oil supplied to the hydraulic cylinder 8 is lower than the predetermined temperature Tset, the second pressure is applied to the solenoid 5a of the variable orifice 5. A signal for minimizing the sectional area of the oil supply path T2 is output. As a result, the opening degree of the throttle portion of the variable orifice 5 becomes minimum, and the second pressure oil supply path T2 has the minimum cross-sectional area. Here, as the cross-sectional area of the second pressure oil supply passage T2 decreases, the pressure difference before and after the variable orifice 5 increases, so that the calorific value increases and the temperature of the pressure oil increases. Therefore, the oil temperature t quickly rises above the threshold Tset by reducing the opening of the throttle portion of the variable orifice 5 to the minimum (step 104). On the other hand, if the result of the determination in step 102 is YES, the oil temperature t has already reached the warm-up temperature, so there is no need to raise the oil temperature t further.
Rather, energy loss due to heat generation becomes large. Therefore, a signal for maximizing the sectional area of the second pressure oil supply passage T2 is output to the solenoid 5a of the variable orifice 5 in order to reduce energy loss. As a result, the opening of the throttle portion of the variable orifice 5 is opened to the maximum, and the second pressure oil supply passage
T2 is the largest cross-sectional area (step 103).

The processes of steps 101 to 104 described above may be performed before the hydraulically driven machine performs work. Here, it is possible to automatically detect that the hydraulic drive machine is in a state before the start of the work and raise the operating oil temperature by the procedure as shown in FIG. That is, steps 201, 203, and 204 in FIG.
In steps 205 and 205, steps 101, 102, 103 and 10 in FIG.
The same processing as in step 4 is executed, and whether or not the operation lever 9 is set to the neutral position (neutral) just before step 203, that is, whether or not the hydraulic drive machine is not working but before the start of work Is determined. This determination process is performed based on the detection signal of the sensor 9a input to the hydraulic device controller 10 (Step 202). Step 202
Only when it is determined that the operation lever 9 is set to the neutral position and the work is not started before the work is not performed,
The process proceeds to the next step 203, in which the warm-up operation process for increasing the oil temperature is performed only when the hydraulic oil temperature t is lower than the predetermined temperature Tset (steps 203 to 205).

Here, since the determination process of step 202 is a process of determining whether or not the operation lever 9 is set to the neutral position, when the operation lever 9 is in the neutral position, not only before starting the work but also when the hydraulic drive Is also included when the work is paused, and when the work is paused also, when the hydraulic oil temperature t has not reached the predetermined temperature Tset, the opening cross-sectional area of the throttle portion of the variable orifice 5 is minimized. Then, a process of raising the operating oil temperature to a predetermined temperature Tset or more is performed.

Therefore, the warm-up operation can be performed in parallel with the excavation work and the like, and the work efficiency is dramatically improved.

 The above is the content of the first control.

2) Second Control (Dead Stroke Control) This second control sets the range of the stroke amount of the operation lever 9 in which the hydraulic cylinder 8 does not operate to a constant range irrespective of the rotation speed of the engine 2, and controls the operation lever 9 This is control for improving the operational feeling. Fig. 8 shows the variable orifice 5
FIG. 9 shows the relationship between the stroke amount of the operating lever and the equivalent opening area of the operating valve in the conventional working machine hydraulic circuit where no hydraulic fluid exists, and FIG. 9 shows the relationship between the stroke amount of the operating lever and the operating speed of the hydraulic cylinder in the prior art. Is shown. Here, the equivalent opening area of the orifice existing at each switching position of the operation valve is determined by L'1 in FIG.
It changes as shown in L'2. That is, the equivalent opening area of the second pressure oil supply passage that connects the hydraulic pump and the drain tank changes as L'1 according to the magnitude of the stroke of the operation lever. This characteristic L'1 is uniquely determined by the type of the operation valve. Similarly, the equivalent opening area of the first pressure oil supply passage connecting the hydraulic pump and the hydraulic cylinder also changes as indicated by L'2 according to the stroke amount of the operation lever. Here, as shown in FIG. 9, there is a dead stroke range in which the hydraulic cylinder does not operate (the speed of the cylinder rod becomes zero) while the stroke amount of the operation lever is small. This dead stroke range is determined by the equivalent opening area of the second pressure oil supply passage. That is, the smaller the equivalent opening area of the second pressure oil supply passage, the smaller the dead stroke range. On the other hand, the lower the rotation speed of the engine, the lower the pressure of the discharge oil of the hydraulic pump, and the larger the dead stroke range of the operation lever. Further, the dead stroke range varies depending on the magnitude of the engine speed.
L'3 in FIG. 9 shows the relationship between the operating lever and the operating speed of the hydraulic cylinder when the engine speed is high.
Shows the relationship between the operating lever and the operating speed of the hydraulic cylinder when the engine speed is low. This clearly shows that the lower the engine speed, the larger the dead stroke range, resulting in a different lever operation feeling. Therefore, in the second control, the opening area of the restricting portion of the variable orifice 5 is reduced as the engine speed decreases, thereby canceling that the dead stroke range increases as the engine speed decreases. The stroke range is always kept constant regardless of the engine speed.

FIG. 4 shows the relationship between the stroke amount of the operation lever 9 and the equivalent opening area of the variable orifice in the embodiment, and FIG. 5 shows the relationship between the stroke amount of the operation lever 9 and the operating speed of the hydraulic cylinder 8. Here, the equivalent opening area of the variable orifice means an opening area obtained by combining the orifice of the operation valve 4 and the variable orifice 5.

In the hydraulic device controller 10, the relationship between the operation lever 9 and the equivalent opening area is set as characteristic lines l1, l'1,... Such that the equivalent opening area decreases as the engine speed decreases as shown by the broken line in FIG. You. Accordingly, the hydraulic controller 10 selects a line corresponding to the current rotational speed of the engine 2 from the lines l1, l'1,... Based on the output of the rotation sensor 18 and the output of the sensor 9a, and operates on the selected line. An urging signal is output to the solenoid 5a to control the opening of the throttle of the variable orifice 5 so that an equivalent opening area corresponding to the operation stroke amount of the lever 9 is obtained. As a result, as shown in FIG. 5, the dead stroke range is high (line L3) and low (line L3) of the rotation speed of the engine 2.
L4) is constant regardless of Therefore, even if the engine speed changes, a constant operation feeling can always be obtained with the operation lever 9, whereby stable work can be performed.

 The above is the content of the second control.

(3) Third Control (Work Mode Switching Control) This third control is a control that reduces energy loss due to drainage of pressure oil to the tank 7 according to the work state.

As described above, the equivalent opening area of the orifice at each switching position of the operating valve in the conventional working machine hydraulic circuit in which the variable orifice 5 does not exist is uniquely determined according to the type of the operating valve (L 'in FIG. 8). 1). The way of setting the line L'1 in FIG. 8 is to reduce the energy loss, when the load pressure increases in the middle of the lever stroke, the entire discharge oil of the hydraulic pump is drained through the second hydraulic oil supply passage. As a result, the operation of the hydraulic cylinder has been unavoidably stopped.

By the way, when a large load is applied to the hydraulic cylinder in a certain operation type, in order to stop the operation of the hydraulic cylinder in balance with the load pressure, the driving force of the working machine must be controlled so that the entire discharge oil of the hydraulic pump is drained. In some types of work, even when a large load is applied to the hydraulic cylinder, the working machine is designed to make sure that the hydraulic cylinder always moves by draining part of the discharge oil from the hydraulic pump instead of draining it in order to improve fine operability. It is desirable to control the driving force of the motor.

Therefore, in this embodiment, the type of work performed by the hydraulic drive machine is divided into a work mode 1 in which it is desirable to drain the entire discharge oil of the hydraulic pump 1 and a work mode 2 in which it is desirable to drain a part of the discharge oil of the hydraulic pump 1. By classifying and changing the opening degree of the throttle portion of the variable orifice 5 according to each operation mode, the discharge oil of the hydraulic pump 1 is drained in its entirety or partially.

FIG. 6 shows the relationship between the stroke amount of the operation lever and the equivalent opening area of the variable orifice in the embodiment. Here, the equivalent opening area of the variable orifice means an opening area obtained by combining the orifice of the operation valve 4 and the variable orifice 5.

In the mode changeover switch 21, the work mode 1 and the work mode 2 are respectively selected by switching the switch 21 on and off. In FIG. 6, work mode 1,
Lines L5 and L6 are set according to the work mode 2.
Here, the line L5 is a characteristic in which the opening of the throttle of the variable orifice 5 is maximized, and the line L6 is a characteristic in which the opening of the throttle of the variable orifice 5 is reduced by a predetermined amount. Therefore, the hydraulic controller 10 selects a line corresponding to the selected work mode from the lines L5 and L6 based on the output of the mode changeover switch 21 and the output of the operation lever 9, and operates the operation lever 9 on the selected line. Solenoid so that an equivalent opening area corresponding to the operation stroke is obtained
An urging signal is output to 5a to control the degree of opening of the throttle section of the variable orifice 5. As a result, when the operation mode 1 is selected, the entire discharge oil of the hydraulic pump 1 can be drained, and when the operation mode 2 is selected, only a part of the discharge oil of the hydraulic pump 1 is drained. And an increase in energy loss can be avoided.

Also, as shown in FIG. 7, the characteristics L8 and L9 of the work mode 1 and the work mode 2 may be set by keeping the opening of the throttle portion of the variable orifice 5 constant regardless of the stroke amount of the operation lever 9. Good.

 The above is the content of the third control.

〔The invention's effect〕

As described above, according to the present invention, the warm-up operation can be performed automatically and quickly without imposing a burden on the operator. Moreover, the warm-up operation is performed only when the operation valve is in the neutral state, and when the operation valve is not in the neutral state, the hydraulic actuator can be operated to perform the original excavation work. The warming-up operation is performed in parallel with the above, and the remarkable effect that the working efficiency is dramatically improved is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram conceptually showing the configuration of an embodiment of a control device for a hydraulic drive machine according to the present invention, and FIGS. 2 and 3 exemplify processing procedures performed by a hydraulic device controller shown in FIG. FIGS. 4, 6, and 7 are graphs showing the relationship between the stroke of the operating lever set by the hydraulic device controller shown in FIG. 1 and the equivalent opening area of the orifice, and FIG. FIG. 4 is a graph showing the relationship between the stroke of the operating lever and the operating speed of the hydraulic cylinder when the equivalent opening area of the orifice changes according to the relationship shown in FIG. 4. FIG. FIG. 9 is a graph showing the relationship of the equivalent opening area. Is a graph showing the operating speed relationship between click volume and the hydraulic cylinder. 1 ... hydraulic pump, 2 ... engine, 4 ... operating valve, 5
... variable orifice, 7 ... drain tank, 8 ... hydraulic cylinder, 9 ... electric operation lever, 9a ... operation stroke amount detection sensor, 10 ... hydraulic device controller, 11 ...
… Solenoid for operating valve, 12 …… Hydraulic oil temperature sensor, 18 ……
Rotation sensor, 20 …… Hydraulic pump discharge oil pressure sensor, 21 ……
Mode changeover switch, T1 ... First pressure oil supply path, T2 ...
Second pressure oil supply path.

Claims (1)

(57) [Claims] A hydraulic pump that is driven by an engine; and a first pressure oil supply path that communicates a hydraulic actuator with an operation valve that is operated by the hydraulic pump, an operation lever, and an operation of the operation lever. A hydraulic drive machine configured to supply hydraulic oil discharged from the hydraulic pump in accordance with an amount to the hydraulic actuator to drive the hydraulic actuator, wherein the hydraulic pump communicates with the operation valve and the drain tank. A second pressure oil supply path, a variable orifice disposed in the second pressure oil supply path and varying a cross-sectional area of the second pressure oil supply path, and a pressure orifice supplied to the hydraulic actuator. Temperature detection means for detecting a temperature, when the operation valve is in a neutral state, and when the temperature of the pressure oil detected by the temperature detection means is lower than a predetermined temperature, A variable orifice control means for performing control to reduce the cross-sectional area of the second pressure oil supply passage so that the temperature is equal to or higher than a predetermined temperature.