JP3444503B2 - Control device for hydraulic drive machine - Google Patents

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 depending on a work mode indicating a work type is disclosed in, for example, Japanese Patent Laid-Open No. 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"). )) To improve the operability of the operating lever, but it is not only the differential pressure that is uniquely changed according to the work mode or engine rotation, but also the output torque of the engine. It was not made on the premise of matching the absorption torque of the hydraulic pump.

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.

The present invention has been made in view of the above circumstances, and by controlling the differential pressure while matching the output torque of the engine with the absorption torque of the hydraulic pump, problems such as engine stall are prevented, and operation is prevented. It is an object of the present invention to provide a device capable of improving the property.

[0008]

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, In a controller for a hydraulic drive machine, which controls the discharge flow rate of the hydraulic pump so that the differential pressure between the discharge pressure of the hydraulic pump and the load pressure of the plurality of work actuators becomes a set value, The rotational speed, the discharge pressure of the hydraulic pump, the load pressure of the plurality of work machine actuators, and the operation amounts of the plurality of flow rate control valves are detected, and the prime mover is detected. The absorption torque of the hydraulic pump is set based on the target rotation speed, and the discharge pressure of the hydraulic pump or the load pressure of the plurality of working machine actuators increases as the detected value of each operation amount of the plurality of flow control valves decreases. The pressure detection value is corrected so that the differential pressure setting value is changed according to the correction pressure, the rotation speed, each operation amount, and the setting value. Further, 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, A plurality of flow rate control valves for controlling the flow rate of the pressure oil supplied to the plurality of work machine actuators in accordance with the operation amount, and a discharge pressure of the hydraulic pump and a load pressure of the plurality of work actuators. A control device for a hydraulically driven machine configured to control a discharge flow rate of the hydraulic pump so that a differential pressure has a set value, wherein the rotational speed of the prime mover and the discharge pressure of the hydraulic pump or the plurality of working machine actuators are used. Load pressure and each operation amount of the plurality of flow control valves are detected, and the absorption torque of the hydraulic pump is set based on the target rotation speed of the prime mover. The absorption torque set value is corrected so that the absorption torque of the hydraulic pump becomes smaller as the detection value of each operation amount of the plurality of flow control valves becomes smaller, and the absorption torque set value is corrected according to the detected value and the corrected absorption torque set value. The differential pressure set value is changed.

[0009]

In other words, according to such a configuration, the rotational speed of the prime mover, the discharge pressure of the hydraulic pump or the load pressure of the plurality of work implement actuators, and the operation amounts of the plurality of flow control valves are detected, respectively, and the target of the prime mover is detected. The absorption torque of the hydraulic pump is set based on the number of revolutions, and the differential pressure set value changes according to each of these detected values and set values. In this way, the differential pressure changes in consideration of the absorption torque of the hydraulic pump, so that it is possible to prevent a situation in which work such as engine stall occurs and work cannot be continued.

[0010]

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 contraction side cylinder chamber of the hydraulic cylinder 4 via the conduits 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 line 23a, and the pilot line 23a is connected to a pilot 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 displacement 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 control valve 37 as a pressure oil of the control pressure Pc. Here, the control valve 36 is
The valve position is changed in response to 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 pipe 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 causes 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. Then, in the control valve 37, the valve position is switched according to the pressure difference applied to each end of the control valve 37, and the discharge amount of the pressure oil corresponding to the switching position is changed to the cylinder chamber on the large diameter side of the regulator 12. Is supplied or discharged to the swash plate 2a and the tilt angle of the swash plate 2a is 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. In this case, the set value of the differential pressure ΔPLS is 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) Here, C is a constant and A is the aperture area of the diaphragm 20.

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.

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, and the tilt angle of the swash plate 2a of the hydraulic pump 2 via the control valve 37 and the regulator 12, that is, the hydraulic pump 2
The discharge amount D (cc / rev) of is controlled.

In this case, the controller 33 outputs a control signal for making the absorption horsepower of the hydraulic pump a constant value as described later. That is, a control signal is output to the control valve 36 so that the absorbed horsepower of the hydraulic pump 2 becomes a constant horsepower according to the input work mode M1, ... And the swash plate 2a of the hydraulic pump 2 is controlled via the control valve 37. Control. 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 for obtaining the differential pressure ΔPLS set as described later. That is, the controller 33 controls the differential pressure as well as the control of the pump absorption horsepower by the same control signal. In this case, the pilot port 37a of the control valve 37 is controlled according to the control signal applied to the solenoid 36a of the control valve 36.
The control pressure Pc applied to is changed, and the differential pressure Δ
PLS is changed. 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.

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 according to 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.

The operation characteristics (a) and (c) of 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. 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 above 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. 4A, this second
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. Then, 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 minimum value Amin, the correction amount is indicated by a dashed line I as indicated by a dashed 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.

Further, 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 correction value Pp 'thus obtained, the above equation (3) yields 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 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 expressed as follows: ΔPLS = min ({ωEτ' / (kPp'A)}
2, ΔPLSmax) (5) is corrected to obtain the corrected differential pressure ΔPLS. 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, it is possible to match the output torque of the engine with the absorption torque of the hydraulic pump. It suffices as long as the hydraulic pump 2 is constant torque control.

[0053]

As described above, according to the present invention,
Since the differential pressure is controlled while matching the output torque of the engine with the absorption torque of the hydraulic pump, problems such as engine stalling are eliminated and operability is improved at the same time.

[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 Control valve 8 operation valve 12 Regulator 33 controller 36 control valve 37 Control valve 44 Pump pressure sensor 45 Operation amount sensor 46 manipulated variable sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI F15B 11/16 F15B 11/16 Z (72) Inventor Hideki Kochichi 2597 Shinnomiya, Hiratsuka-shi, Kanagawa Electronics Division Electronic Systems Co., Ltd. (56) References JP-A-5-10269 (JP, A) JP-A-4-136509 (JP, A) JP-A-3-51502 (JP, A) (58) Fields investigated (Int.Cl) . ⁷ , DB name) F15B 11/00-11/22 F04B 49/00-49/24 E02F 9/20-9/22

Claims (2)

(57) [Claims] 1. A hydraulic pump driven by a prime mover, a plurality of hydraulic actuators driven by the supply of pressure oil discharged from the hydraulic pump through a pressure oil supply passage, and the hydraulic 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 load of the plurality of work actuators. In a control device for a hydraulic drive machine configured to control a discharge flow rate of the hydraulic pump so that a pressure difference between the pressure and a set value, a rotational speed of the prime mover and a discharge pressure of the hydraulic pump or the plurality of While detecting the load pressure of the working machine actuator and each operation amount of the plurality of flow control valves,
The absorption torque of the hydraulic pump is set based on the target rotation speed of the prime mover, and the discharge pressure of the hydraulic pump or the load of the plurality of work machine actuators decreases as the detected value of each operation amount of the plurality of flow control valves decreases. A control device for a hydraulically driven machine, wherein the pressure detection value is corrected so that the pressure becomes large, and the differential pressure setting value is changed according to the correction pressure, the number of revolutions, each operation amount, and the setting value. 2. A hydraulic pump driven by a prime mover, a plurality of hydraulic actuators driven by supply of pressure oil discharged from the hydraulic pump through a pressure oil supply passage, and the hydraulic 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 load of the plurality of work actuators. In a control device for a hydraulic drive machine configured to control a discharge flow rate of the hydraulic pump so that a pressure difference between the pressure and a set value, a rotational speed of the prime mover and a discharge pressure of the hydraulic pump or the plurality of While detecting the load pressure of the working machine actuator and each operation amount of the plurality of flow control valves,
The absorption torque of the hydraulic pump is set on the basis of the target rotation speed of the prime mover, and the absorption torque is set such that the smaller the detected value of each operation amount of the plurality of flow rate control valves, the smaller the absorption torque of the hydraulic pump. A control device for a hydraulic drive machine, which corrects a value and changes the differential pressure setting value according to the detected value and the corrected absorption torque setting value.