JPH06280808A - Control device for hydraulically-operated machine - Google Patents

Abstract

PURPOSE:To improve operational property of a hydraulically-operated machine by detecting engine speed, hydraulic pump delivery pressure and operation lever operating amount, setting hydraulic pump absorption torque based on the detected engine speed and a target engine speed, varying the differential pressure of the pump delivery pressure and the operation machine actuator load pressure and controlling it so that it may not exceed the absorption torque. CONSTITUTION:A control signal responding to an absorption torque set value is input from a controller 33, a delivery pressure detected signal is also input and a swash plate inclination angle of a hydraulic pump 2 is controlled by a torque control valve 47 so that an absorption torque set value can be obtained on the basis of these input signals. On the other hand, a control signal responding to a differential pressure set value is input from the controller 33, detected signals responding to respective detected values of the delivery pressure and the load pressure are also input and the swash plate inclination angle of the hydraulic pump 2 is controlled by a differential pressure control valve 37 so that a differential pressure set value can be obtained on the basis of these input signals. Because the swash plate is thus controlled to vary the differential pressure as taking the absorption torque into consideration, such situation as occurrence of engine stall disabling continuation of the operation can be prevented and also operational property of the operation level can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller for a hydraulically driven machine including a construction machine such as a power shovel, and more particularly, to a change amount of a driving speed of a working machine actuator per constant operation amount of a flow operation valve. The present invention relates to a control device that can be changed according to the operating state of a hydraulic drive machine.

[0002]

2. Description of the Related Art Conventionally, a pressure difference between a discharge pressure of a hydraulic pump and a load pressure of a working machine actuator is instructed from the outside in order to obtain operability of an operating lever according to a work content of a construction machine. A technique for controlling so as to change according to a work mode indicating a work type is disclosed in, for example, Japanese Patent Laid-Open No. 2-7690.
No. 4 publication.

In the technique described in this publication, when the work mode is changed from the "normal work" mode to the "fine operation" mode, the differential pressure becomes smaller than that in the "normal work", and the operation lever is constantly operated. The amount of change in the drive speed of the work implement actuator per amount is smaller than during "normal work",
It is possible to perform more detailed work suitable for the "fine operation" mode.

As a control method of this kind, Japanese Patent Laid-Open No.
There is one disclosed in Japanese Patent No. 164941, in which the so-called metering region, which becomes smaller as the engine speed decreases, is enlarged by controlling the differential pressure so as to decrease as the engine speed decreases. The dead band, which increases as the number of revolutions decreases, is made smaller), and the operability of the operating lever is improved.

[0005]

As described above, in these prior arts, the differential pressure is changed according to the work mode or the engine rotation, whereby the relationship between the operation lever operation amount and the work machine actuator speed (hereinafter referred to as "operation characteristic"). Is used to improve the operability of the operating lever. Specifically, a valve for differential pressure control is provided in the hydraulic circuit that controls the hydraulic pump, and work is performed using this differential pressure control valve. The tilt angle of the swash plate of the hydraulic pump is controlled so that a differential pressure according to the mode or engine rotation can be obtained. However, the control of the swash plate is not performed on the premise that the output torque of the engine and the absorption torque of the hydraulic pump are matched.

Therefore, if it is applied as it is to a hydraulic power shovel or the like having a limited output torque of the engine, there is a disadvantage that the engine is stalled when the load on the working machine becomes large and the work cannot be continued. Become.

On the other hand, in hydraulic power shovels,
There is a control valve for pump absorption torque control that controls the swash plate tilt angle of the hydraulic pump so that the absorption torque of the hydraulic pump matches the output torque of the engine. . However, when controlling the hydraulic pump by making such an absorption torque control valve and the differential pressure control valve coexist without any relation to each other,
Depending on the operating condition, the torque limit may affect the operability of the operating lever.

The present invention has been made in view of such circumstances, and the absorption torque is taken into consideration by the differential pressure control valve while the output torque of the engine and the absorption torque of the hydraulic pump are matched by the absorption torque control valve. It is an object of the present invention to provide a device capable of preventing malfunction such as engine stall and improving operability by controlling the differential pressure.

[0009]

Therefore, in the main invention of the present invention, a hydraulic pump driven by a prime mover and pressure oil discharged from the hydraulic pump are supplied by being supplied through a pressure oil supply passage. A plurality of hydraulic actuators, and a plurality of flow rate control valves which are provided in the pressure oil supply passage and control the flow rate of the pressure oil supplied to the plurality of work machine actuators in accordance with an operation amount, A control device for a hydraulically driven machine, wherein the discharge flow rate of the hydraulic pump is controlled so that the differential pressure between the discharge pressure of the hydraulic pump and the load pressure of the plurality of work machine actuators becomes a set value. Rotation speed detection means for detecting the rotation speed of the hydraulic pump, discharge pressure detection means for detecting the discharge pressure of the hydraulic pump, and load pressure detection for detecting the load pressure of the plurality of work machine actuators Stage, the operation amount of each of the plurality of flow control valves, an operation amount detection means, and the absorption torque of the hydraulic pump is set based on the target rotation speed of the prime mover, and the set absorption torque and the rotation speed are set. The differential pressure is set based on the rotation speed detection value of the detection means, the pressure detection value of the discharge pressure detection means or the load pressure detection means, and the operation amount detection value of the operation amount detection means, and these absorption torque set values are set. And a controller that outputs a control signal corresponding to the differential pressure set value, and a control signal corresponding to the absorption torque set value from the controller, and a detection signal corresponding to the discharge pressure detection value of the discharge pressure detection means. Entered,
A torque control valve that controls the swash plate tilt angle of the hydraulic pump so that the absorption torque setting value is obtained based on these signals, and a control signal corresponding to the differential pressure setting value are input from the controller. , A detection signal corresponding to each pressure detection value of the discharge pressure detection means and the load pressure detection means is input, and the swash plate tilt of the hydraulic pump is set so that the differential pressure set value is obtained based on each of these signals. A differential pressure control valve for controlling the turning angle is provided.

[0010]

In other words, according to this structure, the control signal corresponding to the absorption torque setting value is input from the controller, and the detection signal corresponding to the discharge pressure detection value of the discharge pressure detecting means is input. The swash plate tilt angle of the hydraulic pump is controlled by the torque control valve so that the absorption torque set value is obtained. On the other hand, a control signal corresponding to the differential pressure set value is input from the controller, and a detection signal corresponding to each pressure detection value of the discharge pressure detection means and the load pressure detection means is also input, and a difference signal based on each of these signals is input. The swash plate tilt angle of the hydraulic pump is controlled by the differential pressure control valve so that the pressure set value is obtained. In this way, the torque control valve controls the swash plate so as to obtain the set absorption torque, and the differential pressure control valve controls the swash plate so that the differential pressure changes while taking the absorption torque into consideration. Therefore, it is possible to prevent a situation in which work cannot be continued due to a problem such as engine stalling, and the operability of the operating lever is also improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a control device for a hydraulically driven machine according to the present invention will be described below with reference to the drawings. In the embodiments, a power shovel is assumed as the hydraulically driven machine.

FIG. 1 shows the construction of a working machine hydraulic circuit for driving two kinds of working machines (boom and arm) of the working machines of the power shovel. It should be noted that, in the embodiment, two types of working machines are used to avoid complication of the drawings.
Only one operating valve is shown.

As shown in the figure, the variable displacement hydraulic pump 2
Is driven by the engine 1, and the swash plate 2a of the swash plate 2a is moved according to the movement of the piston 12a of the regulator 12 for driving the swash plate.
The tilt angle of is changed. Then, the discharge flow rate D (cc / rev) per one rotation of the hydraulic pump 2 is changed according to the change of the tilt angle of the swash plate 2a. The engine 1 is provided with a rotation sensor 32 for detecting the rotation speed (r · p · m) ωE of the engine 1, and the detection signal ωE of the rotation sensor 32 is applied to the controller 33.

The pressure oil discharged from the hydraulic pump 2 is supplied to the operation valve 7 via the pipe 9 and the pipes 9a and 9b branching the pipe 9.
8 respectively. The spools of the operation valves 7 and 8 are driven according to the operation amounts S1 and S2 of an operation lever (not shown),
The opening area A of each operation valve is adjusted according to the moving amount of the spool.
1 and A2 change, and the pressure oil having a flow rate corresponding to the change is supplied to the hydraulic cylinders 3 and 4 as the working machine actuators. At this time, the pressure oil flowing out from the operation valve 7 is the conduit 3
It is supplied to the extension side cylinder chamber and the compression side cylinder chamber of the hydraulic cylinder 3 via a and 3b, respectively, to extend and retract the hydraulic cylinder 3, respectively.

Similarly, the pressure oil flowing out from the operation valve 8 is supplied to the extension side cylinder chamber and the compression side cylinder chamber of the hydraulic cylinder 4 via the pipe lines 4a and 4b, and the hydraulic cylinder 4 is extended and contracted respectively. Let

The operating valves 7 and 8 consist of positions N, M and L,
At the neutral position N, the pump port into which the pressure oil discharged from the pump 2 flows is in a closed state, and in the intermediate state from the switching position N to the switching positions L and M, the pressure oil flowing through the operation valve is provided on the spool. Rotating ring variable aperture 20
Squeezed with. Further, at the switching positions L and M, the throttle 20 has a constant area, and at each position, the load pressure of the hydraulic cylinders 3 and 4, that is, the pipelines 3a, 3b, 4a and 4 are provided.
b pressure reducing valves 25a, 25b, 26a respectively disposed in b
The pressures on the outlet side of and 26b are introduced to the check valves 21 and 22 via the port R, respectively.

The check valve 21 is connected to a pilot pipe line 23a, and the pilot pipe line 23a is connected to a pilot pipe line 23b. The check valve 22 is connected to the pilot line 23b. The pilot conduit 23b is connected to the pilot conduit 24. Therefore, the pressure oil on the high pressure PLS side of the hydraulic cylinders 3 and 4 is guided to the pilot conduit 24 through either of the check valves 21 and 22. The pilot line 24 is connected to the pressure reducing valves 25a, 25b, 26a and 26b on the side of the spring position, and as a result, the pressure reducing valves 25a, 25b, 26 are connected.
The load pressure PLS on the high pressure side of the hydraulic cylinders 3 and 4 is applied to the spring position side of a and 26b. On the side facing the spring, pressure oil on the inlet side of the pressure reducing valve, that is, the operating valve 7,
The pressure on the outlet side of 8 is applied as the pilot pressure. In addition, the pipeline 10 uses the pressure oil of the operation valves 7 and 8 for the tank 11
It is provided for relief.

The constant capacity hydraulic pump 34 discharges pressure oil of a predetermined pressure, and this discharge pressure oil is a conduit 35 and a control valve 36 (so-called "LS-EPC valve").
Is supplied to the pilot port 37a of the differential pressure control valve 37 as pressure oil of the control pressure Pc. Here, the control valve 36
The valve position is changed in accordance with a control signal applied from the controller 33 to the electromagnetic solenoid 36a, whereby the flow rate of the pressure oil supplied to the pilot port 36a is changed.

A relief valve 38 is provided in the conduit 35, and when the pressure of the hydraulic oil discharged from the hydraulic pump 34 becomes equal to or higher than the pressure set by the relief valve 38, the relief valve 38 relieves the relief. To be done.

The discharge-side pipe line 9 of the hydraulic pump 2 is branched into a pilot pipe line 14, which is connected to the small diameter side cylinder chamber of the regulator 12 and to the pilot port 37b of the control valve 37. It is connected. The pilot line 23b is extended to the pilot port 37 on the side where the spring 37d of the control valve 37 is located.
connected to c. Therefore, the spring 37 of the control valve 37
The discharge pressure Pp of the hydraulic pump 2 and the control pressure Pc from the control valve 36 are provided at the end on the side where there is no d, and the hydraulic cylinders 3 and 4 are provided at the end on the side where the other spring 37d of the control valve 37 is present. The pressure PLS on the high pressure side of the load pressure is the pilot pressure,
Further, the biasing force of the spring 37d is applied as an offset pressure. In the differential pressure control valve 37, the valve position is switched according to the differential pressure of the pressure applied to each end of the differential pressure control valve 37, and the pressure oil having the discharge amount according to the switching position is supplied to the regulator 1.
It is supplied to or discharged from the cylinder chamber on the large diameter side of 2 through the pipe line 48, and the tilt angle of the swash plate 2a is controlled.

The pipe line 48 communicates with a torque control valve 47 for controlling the absorption torque of the hydraulic pump 2. Finally, the tilting angle of the swash plate 2a is controlled by the differential pressure control valve 37 and the torque control valve 47. Will be controlled.

In this case, the tilt angle of the swash plate 2a is controlled so that the pressure difference ΔPLS between the hydraulic pump pressure Pp and the cylinder load pressure PLS is maintained at a set value as described later. The set value of the differential pressure ΔPLS is equal to the control pressure P
c, that is, from the controller 33 to the electromagnetic solenoid 36a
Is changed according to the control signal applied to the.

At this time, the relationship between the pressures Pp and PLS and the discharge amount (volume) D of the hydraulic pump 2 is expressed by the following equation (1).

D = C · A · √ (Pp-PLS) (1) where C is a constant and A is the aperture area of the diaphragm 20.

One end of the torque control valve 47 is the regulator 1
The spring 4 is attached to the pushing member 12b that pushes the second piston 12a.
7c and the pilot port 47b at the other end is connected to the pump discharge pressure Pp in the pipeline 14.
Is added as pilot pressure. Further, an electromagnetic solenoid 47a is provided on the same side as the pilot port 47b.
Is provided, and a control signal from the controller 33 is applied to the solenoid 47a.

The torque control valve 47 controls the tilt angle of the swash plate 2a so that the pump absorption torque does not exceed the torque τ instructed by the controller 33. That is, the controller 33 outputs a control signal instructing the torque τ to the solenoid 47a of the torque control valve 47, and the swash plate position input via the pushing member 47c, that is, the pump capacity D and the pilot port 47b. The valve position is moved and the swash plate 2a is controlled so as not to exceed the torque τ instructed by the discharge pressure Pp that is input.

The engine 1 has a fuel injection pump 38.
Governor 39 is attached. The fuel control lever 39a of the governor 39 is driven by the motor 40, and the drive position of the lever 39a is detected by the position sensor 41. The detection signal of the position sensor 41 is added to the controller 33 as a feedback position signal when driving and controlling the motor 40.

The throttle dial 42 sets a target rotation speed of the engine 1, and a throttle signal corresponding to the target rotation speed ωTH is added to the controller 33. Further, the monitor panel 43 selects and instructs a work mode M performed by the power shovel, that is, a "heavy excavation" mode M1, a "excavation" mode M2, a "rectification" mode M3, and a "fine operation" mode M4. And the selected work mode M1,
Signals indicating M2, M3, M4 are applied to controller 33.

A pump pressure sensor 44 is provided in the pipe line 14.
The sensor 44 detects the pressure of the pressure oil in the conduit 14, that is, the pressure oil Pp discharged from the hydraulic pump 2. This detected value Pp is added to the controller 33.

Further, the operation valves 7 and 8 are provided with operation amount sensors 45 and 46 for detecting operation stroke amounts (hereinafter referred to as "operation amount") S1 and S2, respectively.
1, S2 are added to the controller 33.

The controller 33 outputs a drive control signal to the motor 40 based on various input signals,
The output torque of the engine 1 is controlled. That is, as shown in FIG. 2, the motor 40 is set so that the regulation lines l1, l2, l3, ... Are set according to the input target revolution speed ωTH and the current engine revolution speed ωE detected by the engine revolution sensor 32. A drive control signal is applied to the fuel control lever 39a and the fuel control lever 39a is activated.

On the other hand, the controller 33 executes arithmetic processing as described later on the basis of various input signals,
The control signal obtained as a result is applied to the solenoid 3 of the control valve 36.
6a as well as to the electromagnetic solenoid 47a of the torque control valve 47, and the swash plate 2 of the hydraulic pump 2 via the differential pressure control valve 37, the torque control valve 47, and the regulator 12.
The tilt angle of a, that is, the discharge amount D (cc / r of the hydraulic pump 2
ev) is controlled.

In this case, the controller 33 outputs to the torque control valve 47 a control signal for making the absorption horsepower a constant value as described later. That is, a control signal is output to the torque control valve 37 so that the absorbed horsepower of the hydraulic pump 2 becomes a constant horsepower according to the input work mode M1.
The swash plate 2 a of the hydraulic pump 2 is controlled via the torque control valve 37. In this way, the matching point moves to the most efficient point according to the current load state (see F in FIG. 2). On the other hand, the controller 33 outputs a control signal to the control valve 36 so that the differential pressure ΔPLS set as described later is obtained. That is,
The controller 33 controls not only the pump absorption horsepower but also the differential pressure. In this case, the control pressure Pc applied to the pilot port 37a of the control valve 37 in accordance with the control signal applied to the solenoid 36a of the control valve 36 is Change, which changes the differential pressure ΔPLS. In this embodiment, the differential pressure ΔPLS is changed in accordance with various control modes described later to improve the operability of the operation levers (not shown) of the operation valves 7 and 8.

The details of the variable control of the differential pressure ΔPLS will be described below.

First Control In this first control, the rotational speed ωE of the engine 1 and the discharge pressure Pp of the hydraulic pump 2, that is, the load pressure PLS of the work machine actuators 3 and 4 and the operation valves 7 and 8 are operated. Amount S1,
S2 and S2 are detected respectively, and the absorption torque τ of the hydraulic pump 2 is set based on the target rotation speed ωTH of the engine 1 and the detected rotation speed ωE according to the equal horsepower control. Differential pressure ΔPLS
By changing the value, the control for limiting the absorption torque of the hydraulic pump 2 is performed to prevent the occurrence of problems such as engine stall and also to obtain good lever operability.

Generally, between the rotational speed ωE of the engine 1, the discharge pressure Pp of the hydraulic pump 2, the sum A of the opening areas of the operating valves 7 and 8, the absorption torque τ of the hydraulic pump 2 and the differential pressure ΔPLS. , And the relationship expressed by the following equation (2) is established.

√ (ΔPLS) = ωEτ / (kPpA) (2) where A = ΣA1 to An (1 to n mean each operating valve, and in this embodiment, A1 + A2)
It becomes). The above equation (2) is obtained as follows. That is, the discharge amount Q (cc / mi of the hydraulic pump 2
The relationship of Q = D · ωE holds between n) and the volume D, and the absorption torque τ of the pump 2 is expressed as τ = D · Pp = τ (ωE, ωTH). Then, from the above-mentioned formula (1), Q = C · A · √ (ΔPLS) holds. Therefore, the above equation (2) is obtained by eliminating Q and D from these equations. The pump discharge pressure Pp
And actuator load pressure PLS are substantially the same,
It is also possible to use PLS instead of Pp in the equation (2).

On the other hand, the maximum value of the discharge amount Q of the hydraulic pump 2 is automatically determined when the operation valves 7 and 8 are operated to the maximum operation amount at the maximum rotation of the engine 1. Therefore, it is necessary to obtain the maximum value of the discharge amount Q in advance and set the corresponding maximum differential pressure to ΔPLSmax so that the differential pressure ΔPLS obtained by the above equation (2) does not exceed the maximum differential pressure ΔPLSmax. After all, the differential pressure ΔPLS is obtained by ΔPLS = min ({ωE · τ / (k · Pp · A)} 2, ΔPLSmax) (3). ΩE · τ / in equation (3)
ΩE, Pp, and A of (k · Pp · A) can be obtained from the detection values of the corresponding sensors, and τ is the absorption torque of the hydraulic pump 2 based on the target rotational speed ωTH of the engine 1 and the detected rotational speed ωE. It can be obtained by setting τ according to equal horsepower control. The total opening area A may be obtained as the sum of the outputs S1 and S2 of the operation amount sensors 45 and 46, or may be obtained as the larger value of the outputs S1 and S2 of the operation amount sensors 45 and 46. You may do it.

Here, as described above, the work mode M1 ...
The horsepower to be set differs according to (the horsepower lines shown in FIG. 2 are different), and the absorption torque τ set accordingly also differs. Therefore, the right-hand side ωE · τ / (k · Pp ·
A) for each work mode M1 ... Engine speed ωE ...
It is also possible to prepare a plurality of functions each having a variable as a variable, select a function corresponding to the selected work mode M1, ... And calculate the differential pressure ΔPLS according to the selected function.

Further, the above function ωE · τ / (k · Pp ·
It is also possible to prepare A) for each drive state of the work machine actuators 3 and 4, that is, according to which work machine is driven in which direction. For example, when the boom is raised, the load is large and the absorption torque τ needs to be set large, and when the bucket is operating, the load is relatively small and the absorption torque τ may be set small. This is because the magnitude of torque differs depending on the driving state. The operation amount detection sensors 45 and 46 determine which working machine is driven in which direction.
Can be detected based on the output of

Further, the maximum differential pressure ΔPLSmax also depends on the selected work mode M1 ...
Since it depends on the driving state of No. 8, it can be determined according to them.

Therefore, in this first control, the above-mentioned function is selected in accordance with the selected work mode M1 ... And the types of the actuators 3 and 4 currently driven detected by the operation amount sensors 45 and 46 and their driving directions. Is selected and the engine speed ωE ... Is substituted into the selected function to obtain the differential pressure ΔPLS in the above equation (2). On the other hand, the selected work mode M1 ... And operation amount sensor 4
5, the maximum differential pressure value ΔPLSmax is obtained according to the type of the actuators 3 and 4 currently driven detected at 5, 46 and the driving direction thereof, and the smaller differential pressure ΔPLS is obtained by the above equation (3), A control signal for obtaining the obtained differential pressure ΔPLS is output to the control valve 36. On the other hand, the absorption torque τ set above
The control signal for obtaining (ωE, ωTH) is the torque control valve 4
7 and the swash plate 2a is controlled by the torque control valve 47 so as not to exceed the absorption torque τ.

The operation characteristics (a) and (c) in FIG. 3 show the relationship between the operation amounts S1 and S2 and the working machine actuator driving speeds v1 and v2 under the first control when the load is small and the load is small. This is a case where the load Pp is large, and the differential pressure ΔPLS becomes smaller as the load Pp becomes larger according to the equation (2). Therefore, even if the load Pp becomes large, the characteristic (a) changes to the large dead band characteristic (b). Without shifting, the characteristic shifts to the characteristic (c) with a small inclination, whereby the dead band remains small as in the characteristic (a) when the load Pp is small, and good operability is maintained. Moreover, since equal horsepower control of the absorption torque of the hydraulic pump 2 is also performed at the same time, problems such as engine stall do not occur. The characteristic (b) indicated by the broken line in FIG. 3 is obtained when the control not based on the above equation (2) is performed.
It can be seen that due to torque limitation when the load is large, the dead band spreads and operability deteriorates.

Second control In the first control, the differential pressure ΔPLS is calculated according to the equation (2).
Since it is changed, it is possible to obtain a good operability suitable for the load which the working machine is currently subjected to. However, in this second control, the load Pp in the above formula (2) is corrected to improve the accuracy. It is intended to perform good control.

By the way, FIG. 4C shows the pump discharge pressure Pp.
And the pump discharge amount Q are shown. Generally, the smaller the total sum A of the opening areas, that is, the smaller the operation amounts S1 and S2 of the operating lever, the more the PQ curve is applied. The change causes a change in the flow rate Q as shown by G, which appears as a change in the differential pressure, which adversely affects the operability.

After all, as shown in FIG.
In the control of, the detected value Pp of the pump discharge pressure is set to the total opening area A
The detection value Pp is corrected so that the discharge pressure Pp 'gradually increases as the value of P becomes smaller as shown by the broken line H and the alternate long and short dash line I. In FIG. 5A, the solid line J shows the relationship between the detection value Pp and the correction value Pp 'when the total opening area A is the maximum value Amax. When the total opening area A is maximum, Since the operability does not deteriorate, the detected value P
No correction is applied to p. When the total opening area A is larger than the minimum value Amin and smaller than the maximum value Amax, the above correction is performed as indicated by a broken line H, and when the total opening area A is the maximum value Amax, the correction amount is indicated by a dashed line I as indicated by a broken line H. It is larger than the case to cope with the deterioration of operability.

It should be noted that the reason why the correction amount is made smaller as the detected value Pp becomes larger is that the fluctuation range of the flow rate Q becomes smaller as the pump pressure Pp becomes larger, as is clear from FIG. 4 (c). This is because the fluctuation becomes small and the correction does not need to be performed much.

As shown in FIG. 4B, the contents of FIG. 4A are the pump pressure detection value Pp, the total opening area A, and the correction value Pp.
It is also possible to represent the relationship with ‘′ as a three-dimensional map K and perform the correction according to the three-dimensional map K.

Therefore, in this second control, as shown in FIG.
Alternatively, the contents of FIG. 9B are stored in advance in a memory (not shown) in the controller 33. Then, the detected value Pp of the pump pressure sensor 44 and the operation amount sensors 45, 4
Based on the detected values S1 and S2 of 6, the corresponding correction value Pp 'in (a) or (b) of FIG. 4 is read out. In this case, the total opening area A may be obtained from the total of the manipulated variables S1 and S2, or may be determined as the larger of the manipulated variables S1 and S2.

Then, using the thus obtained correction value Pp ', the above equation (3) gives ΔPLS = min ({ωE · τ / (k · Pp ′ · A)} 2, ΔPLSmax) (4) Then, a control signal for obtaining the corrected differential pressure ΔPLS is output to the control valve 36. As a result, the operability of the operating lever in the fine speed region is further improved.

Third control In the first control, the differential pressure ΔPLS is calculated according to the equation (2).
Since it is changed, it is possible to obtain a good operability suitable for the load that the working machine is currently applying. However, in this third control, the absorption torque τ in the above equation (2) is corrected to improve the accuracy. It is intended to perform good control.

The equation (2) is an equation for obtaining the differential pressure ΔPLS so as not to exceed the absorption torque τ on the PQ curve.
Therefore, when the operating lever operation amount is small, which is not restricted by the horsepower by the PQ curve, the engine output and the pump load are matched with a torque equal to or less than the absorption torque τ (maximum value), and the flow rate corresponding to the lever stroke may flow. It is in a state. Therefore, the detected value S1 of the operation amount,
The smaller the S2, the smaller the absorption torque (2)
This is dealt with by correcting the torque τ in the equation to τ ′.

Therefore, in the third control, an arithmetic expression or the like for obtaining the correction value τ ′ so that the torque τ becomes smaller as the detection value A of the total opening area becomes smaller is stored in advance in a memory (not shown) in the controller 33. Be done. And
The correction value τ ′ is calculated based on the detected values S1 and S2 of the operation amount sensors 45 and 46 and the stored contents. In this case, the total opening area A may be obtained from the total of the manipulated variables S1 and S2, or may be determined as the larger of the manipulated variables S1 and S2.

Then, using the correction torque τ ′, the above equation (3) is corrected to ΔPLS = ({ωE · τ ′ / (k · Pp ′ · A)} 2, ΔPLSmax) (5), The corrected differential pressure ΔPLS is obtained. Then, the control signal for obtaining the obtained corrected differential pressure ΔPLS is output to the control valve 36, and the operability in the fine speed region is further improved.

As described above, according to this embodiment,
The engine speed, the discharge pressure of the hydraulic pump, and the operation amounts of the operating valve are respectively detected, and the absorption torque of the hydraulic pump is set, and a predetermined value is established between each detected value and set torque and the differential pressure ΔPLS. Differential pressure Δ
Since the PLS is changed, the optimum lever operability suitable for the current work state can be obtained, and the work efficiency can be dramatically improved.

Although this embodiment has been described on the assumption that the hydraulic pump 2 is controlled to have a uniform horsepower as shown in FIG. 2, the output torque of the engine and the absorption torque of the hydraulic pump can be matched. It suffices as long as the hydraulic pump 2 is constant torque control.

[0057]

As described above, according to the present invention,
Since the differential pressure control valve and the torque control are used to control the differential pressure while matching the output torque of the engine and the absorption torque of the hydraulic pump, problems such as engine stall are eliminated and operability is improved at the same time. Is obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a working machine hydraulic circuit in an embodiment of a control device for a hydraulically driven machine according to the present invention.

FIG. 2 is a graph showing the relationship between the engine speed and the output torque of the engine.

FIG. 3 is a graph showing the relationship between the operation amount of the operation lever and the drive speed of the working machine actuator in the embodiment.

FIG. 4 is a graph used for explaining an embodiment in which the pump discharge pressure is corrected according to the total opening area of the operation valve.

[Explanation of symbols]

 2 hydraulic pump 3 hydraulic cylinder 4 hydraulic cylinder 7 operation valve 8 operation valve 12 regulator 33 controller 36 control valve 37 differential pressure control valve 44 pump pressure sensor 45 operation amount sensor 46 operation amount sensor 47 torque control valve

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display location F15B 11/16 Z 9026-3H (72) Inventor Hideki Kunichi 2597 Shinnomiya, Hiratsuka-shi, Kanagawa Komatsu Co., Ltd. Factory Electronics Division, Electronic Systems Division

Claims (4)

[Claims] 1. A hydraulic pump driven by a prime mover, a plurality of hydraulic actuators driven by supplying pressure oil discharged from the hydraulic pump through a pressure oil supply passage, and a plurality of hydraulic actuators provided in the pressure oil supply passage. And a plurality of flow rate control valves for controlling the flow rate of the pressure oil supplied to the plurality of working machine actuators according to the operation amount, and the discharge pressure of the hydraulic pump and the plurality of working machine actuators. In a control device for a hydraulic drive machine configured to control a discharge flow rate of the hydraulic pump so that a differential pressure with a load pressure has a set value, a rotation speed detection unit that detects a rotation speed of the prime mover, Discharge pressure detection means for detecting the discharge pressure of the hydraulic pump, load pressure detection means for detecting the load pressure of the plurality of work implement actuators, and operation amounts of the respective operation amounts of the plurality of flow control valves. Output means, and set the absorption torque of the hydraulic pump based on the target rotation speed of the prime mover, the set absorption torque, the rotation speed detection value of the rotation speed detection means and the discharge pressure detection means or the load. A controller that sets the differential pressure based on the pressure detection value of the pressure detection means and the operation amount detection value of the operation amount detection means, and outputs a control signal corresponding to the absorption torque setting value and the differential pressure setting value, respectively. A control signal corresponding to the absorption torque set value is input from the controller and a detection signal corresponding to the discharge pressure detection value of the discharge pressure detection unit is input, and the absorption torque set value is obtained based on these signals. And a torque control valve for controlling the tilt angle of the swash plate of the hydraulic pump, and a control signal according to the differential pressure set value is input from the controller. A detection signal corresponding to each pressure detection value of the discharge pressure detection means and the load pressure detection means is input, and the swash plate tilting of the hydraulic pump is performed so that the differential pressure set value is obtained based on each of these signals. A control device for a hydraulically driven machine, comprising a differential pressure control valve for controlling a corner. 2. The controller corrects the pressure detection value of the discharge pressure or the load pressure such that the discharge pressure or the load pressure increases as the detection value of each operation amount of the plurality of flow rate control valves decreases. The control device for a hydraulically driven machine according to claim 1, wherein the differential pressure is set according to the corrected pressure. 3. The controller corrects the absorption torque set value such that the absorption torque of the hydraulic pump becomes smaller as the detected value of each operation amount of the plurality of flow rate control valves becomes smaller, and the corrected absorption torque is set to the corrected absorption torque. The control device for a hydraulically driven machine according to claim 1, wherein the differential pressure is set in accordance with the difference. 4. A hydraulic pump driven by a prime mover, a plurality of hydraulic actuators driven by supplying pressure oil discharged from the hydraulic pump through a pressure oil supply passage, and a plurality of hydraulic actuators provided in the pressure oil supply passage. And a plurality of flow rate control valves for controlling the flow rate of the pressure oil supplied to the plurality of work machine actuators according to the operation amount, and the discharge pressure of the hydraulic pump and the plurality of work machine actuators. In a control device for a hydraulically driven machine that controls a discharge flow rate of the hydraulic pump so that a pressure difference with a load pressure becomes a set value, a work type instruction for selecting and instructing a work type performed by the hydraulically driven machine. Means, a rotation speed detection means for detecting the rotation speed of the prime mover, a discharge pressure detection means for detecting the discharge pressure of the hydraulic pump, and a load pressure of the plurality of work machine actuators. A load pressure detection means for outputting, an operation amount detection means for operating each operation amount of the plurality of flow control valves, and a work machine type detection for detecting a type of a work machine actuator currently driven among the plurality of work machine actuators Means, a target rotation speed of the prime mover, a work type instructed by the work type instructing means, and a type of a work machine actuator detected by the work machine type detecting means, and sets the absorption torque of the hydraulic pump. At the same time, the differential pressure is set based on the set absorption torque, the pressure detection value of the discharge pressure detection means or the load pressure detection means, and the operation amount detection value of the operation amount detection means. Controller that outputs a control signal corresponding to the set value and the differential pressure set value, and a control signal that corresponds to the absorption torque set value from the controller. Is input and a detection signal corresponding to the discharge pressure detection value of the discharge pressure detection means is input, and the swash plate tilt angle of the hydraulic pump is adjusted so that the absorption torque setting value is obtained based on each of these signals. A torque control valve to be controlled and a control signal corresponding to the differential pressure set value are input from the controller, and detection signals corresponding to the pressure detection values of the discharge pressure detection means and the load pressure detection means are input. A controller for a hydraulically driven machine, comprising: a differential pressure control valve that controls a swash plate tilt angle of the hydraulic pump so that the differential pressure set value is obtained based on each of these signals.