JPH01150002A - Hydraulic driving device - Google Patents

Abstract

PURPOSE:To improve pumping efficiency by driving an actuator under the condition that the rotational speed of a motor is set lower than the maximum rotational speed. CONSTITUTION:Outputs from a tilting angle sensor 4 and a rotation sensor 5 are input to a controller 9. When the maximum tilting angle theta max of a pump is larger than a necessary tilting angle theta, a signal corresponding to a reference rotational speed A is output to a motor 1b, on the other hand when the maximum tilting angle theta max is smaller than the necessary tilting angle theta, a necessary rotational speed is output to the motor 1b. Pumping efficiency is improved since an actuator can be driven under the condition that the rotational speed of a prime mover is set lower than the maximum rotational speed in any case.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic drive device provided in a hydraulic machine such as a hydraulic excavator.

[Prior art]

Conventionally, a hydraulic excavator for excavating earth and sand, for example, has been equipped with a hydraulic drive device, and this hydraulic drive device includes a prime mover, that is, an engine, a governor, and a motor, and controls the rotation speed N of the engine. a variable displacement hydraulic pump driven by an engine, a regulator that controls the discharge volume of the variable displacement hydraulic pump, that is, a pump tilting angle θ, and a boom cylinder and arm driven by hydraulic pressure discharged from the pump. Includes pressure compensation for actuators such as cylinders, packet cylinders, swing motors, travel motors, and boom directional control valves, arm directional control valves, packet directional control valves, etc. that control the flow of hydraulic pressure supplied from the pump to the actuators. Flow rate control valve and switching control of this flow rate control valve with pressure compensation,
A control device that controls the drive of the regulator and the rotation of the engine, a boom control lever and an arm control lever that command the drive of the boom cylinder, arm cylinder, packet cylinder, swing motor, travel motor, etc.
It is equipped with operating devices such as a packet operating lever, a turning operating lever, and a traveling operating lever.

Then, by selectively operating each of the above operating levers and driving the engine, Q=N·θ, which is the product of engine rotational speed N and pump tilt angle θ, is obtained.

The pump flow rate is supplied to the corresponding actuator via the corresponding flow control valve, and, for example, the boom, arm, and packet rotate to perform earth and sand excavation work.

[Problem that the invention seeks to solve]

By the way, in the conventional hydraulic excavator mentioned above, each actuator is usually driven with the engine rotation speed fixed at the maximum rotation speed. The boom is operated by a boom cylinder, and the arm is operated by an arm cylinder.
In practice, when driving the engine, a flow rate so large that the pump tilting angle θ2 has to be set to the maximum tilting angle θmax is required while the engine rotational speed is set to the maximum rotational speed.
When driving a revolving body operated by a revolving motor, when the engine speed is at its maximum, the maximum tilting angle θ of the pump
Only a tilt angle of about 30% of the maximum is required (corresponding to the position where the flow rate Q is 30% in FIG. 6), and therefore the pump efficiency is poor. Also, when driving, half of the total flow rate of one pump is supplied to the two travel motors, so if only one travel motor is driven, the pump tilt angle will be 50% of the maximum tilt angle. (corresponding to the position where the flow rate Q is 50% in Fig. 6), and there is still a problem with pump efficiency.

In addition, in FIG. 6, 25 indicates a pump efficiency curve.

As mentioned above, in the conventional method, the engine speed is set to the maximum speed and the tilting angle of the pump is made small, which results in poor pump efficiency (and poor fuel efficiency, resulting in economic problems). There is also the problem of noise.

The present invention has been made in view of the actual situation in the prior art described above, and an object thereof is to provide a hydraulic drive device that can improve pump efficiency.

[Means for solving problems]

In order to achieve this object, the present invention provides a prime mover, a rotation speed control means for controlling the rotation speed of the prime mover, a variable displacement hydraulic pump driven by the prime mover, and a discharge volume of the variable displacement hydraulic pump. a regulator to control;
A regulator control means for controlling the drive of the regulator, an actuator driven by pressure oil discharged from the variable displacement hydraulic pump, an operating device for commanding the drive of the actuator, and a supply supply from the variable displacement hydraulic pump to the actuator. a flow rate control valve capable of controlling the flow of pressurized oil and supplying a flow rate according to the operation amount of the operating device without depending on a change in the load pressure applied to the actuator; and switching control of the flow rate control valve. and a control device for controlling rotation of the prime mover, wherein the control device includes a required flow rate setting means for setting a flow rate of pressure oil required for driving the actuator, and a rotation speed of the prime mover. a reference rotation speed setting means that sets the base unit rotation speed in advance to be lower than the maximum rotation speed under no load, and the required flow rate set by the above-mentioned required flow rate setting means and the reference rotation speed setting means. a calculation means for calculating the required pump tilting angle from the reference rotation speed; a comparison means for comparing the required pump tilting angle with the maximum tilting angle of the variable displacement hydraulic pump; Comparison of the computation means for calculating the required rotation speed of the prime mover from the maximum tilt angle and the required flow rate when it is determined that the maximum tilt angle is smaller than the pump tilt angle, and the comparison means. The configuration includes output means for selectively outputting either the reference rotation speed or the required rotation speed according to the result.

[For production]

Since the present invention is configured as described above, as long as the required flow rate of the actuator does not exceed the pump flow rate, if the maximum tilting angle θwax of the pump is larger than the required tilting angle θ, the control device A signal corresponding to the reference rotation speed A is output to the rotation speed control means, and the maximum tilt angle θwax is
is smaller than the required tilt angle θ, the required rotational speed is output to the rotational speed control means. In either case, the actuator is driven with the rotational speed of the prime mover lower than the maximum rotational speed, thereby improving pump efficiency.

〔Example〕

Hereinafter, the hydraulic drive device of the present invention will be explained based on the drawings.

FIG. 1 is an explanatory diagram showing the overall configuration of an embodiment of the present invention.
This embodiment shows a drive device installed in a hydraulic excavator. In this embodiment, a prime mover or engine 1,
A rotation speed control means including a governor 1a and a motor 1b that control the rotation speed N of this engine 1, a variable displacement hydraulic pump 2 driven by the engine 1, and this hydraulic pump 2
A tilt angle sensor 4 detects the tilt angle of the pump 2, a rotation sensor 5 detects the rotation speed of the engine 1, and a regulator 3 for controlling the discharge capacity of the pump 2.
A pressure sensor 8 is provided to detect the pressure of the pressure oil discharged from the pressure oil.

Also, a boom cylinder 7a and an arm cylinder 7b are driven by pressure oil discharged from the pump 2.

Packet cylinder 1cs actuators such as left travel motor 7d, right travel motor 7e, swing motor 7f, breaker 74, boom directional control valve 6a for controlling the flow of pressure oil supplied to these actuators from pump 2, and arm. Directional control valve 6b.

Packet directional control well 6C1 left travel directional control valve 6d,
Flow rate control valves with pressure compensation such as the right travel direction control valve 6e, the turning direction control valve 6f, and the breaker direction control valve 6g, the boom operation lever 10a that commands the drive of the above-mentioned actuator i, and the arm operation. Operating devices such as a lever 10b, a packet operating lever 10c, a left running operating lever 10d, a right running operating lever 10e, a turning operating lever 10f, and a breaker operating lever 10g, and an engine lever 11 that commands the drive of the engine l. It is equipped with

It also includes a control device 9 that performs switching control of each of the directional control valves 6a to 6g, drive control of the regulator 3, and rotation control of the engine 1.
The drive unit of the engine 1, each of the operation levers 10a to 10g1, the engine lever 11, the tilt angle sensor 4, the rotation sensor 5, and the pressure sensor 8 are connected to this control device 9. This control device 9 has a memory.

It is composed of, for example, a microcomputer having calculation and logical judgment functions, and has built-in setting means, calculation means, comparison means, and output means.

The above-mentioned setting means include the boom, arm required flow characteristic line 26, packet required flow characteristic line 27, traveling,
A required flow rate setting means for setting the relationship of the actuator required flow rate to the flow rate of pressure oil required for driving the actuator, that is, the lever stroke, as exemplified by the preliminary required flow rate characteristic line 28 and the swing required flow rate characteristic line 29; Output horsepower characteristic line 30 and torque characteristic line 31 in Fig. 3
, in view of the fuel consumption rate characteristic line 32, a maximum rotation speed setting means for setting the maximum rotation speed B of the engine 1 under no load, and a reference rotation speed A that is lower in advance than the maximum rotation speed B, for example, when the torque is at the maximum value. A left curve PQ, which is the relationship between the reference rotation speed A, and the pressure P and flow rate Q of the pressure oil discharged from the pump 2 (as shown in the above-mentioned FIG. 6)
PQ left curve setting means for setting the PQ left curve, and maximum tilting angle setting means for setting the maximum tilting angle θmax of the pump 2.

Further, the above-mentioned calculation means includes a first calculation means for calculating the total value Q of the required flow rate of each of the above-mentioned actuators, and P
a second calculating means for calculating the pump flow rate Q from the pressure P detected by the Q left curve pressure sensor 8;
A third calculation means calculates the pump tilt angle θ from the pump flow rate Q and the engine rotation speed N obtained by the calculation means, and calculates the required rotation angle θ from the above-mentioned reference rotation speed A and the total value QL of the required flow rate. It includes a fourth calculation means for calculating the angle θ, and a fifth calculation means for calculating the required rotation speed Na from the maximum tilt angle θmax of the pump 2 and the total value QL of the required flow rate.

Further, the above-mentioned comparison means includes a first comparison means that compares the flow rate Q obtained by the above-mentioned second calculation means and the total value QL of the required flow rate obtained by the above-mentioned first calculation means, and a pump 2
and a second comparison means for comparing the maximum tilt angle θmax of 1 and the required tilt angle θ obtained by the fourth calculation means.

Further, the above-mentioned output means is the pump tilt angle θ.

a first output section that outputs the maximum rotational speed B as a signal to the regulator 3 and the maximum rotational speed B to the rotational speed control means described above; The second output section that outputs and the maximum tilt angle θm
ax to the regulator 3 and a third output section that outputs the required rotational speed Na to the rotational speed control means as a signal.

In the embodiment configured as described above, the engine 1 rotates as the engine lever 11 is operated, and the pump 2 is integrally driven. And each operating lever tOa~10
In accordance with the selective operation of g, a signal is output from the control device 9 to the drive section of one of the corresponding directional control valves 6a to 6g, the corresponding directional control valve is switched, and the pump 2 discharges. The pressure oil is supplied to the corresponding actuator via the corresponding directional control valve, and driving bodies such as booms and arms related to the corresponding actuator are driven. In this case, for example, when performing a combined arm and packet operation, the control device 9 performs the processing shown in the flowchart of FIG. 4.

As shown in step S1 in FIG. 4, first, operate lever 1.
In addition to reading the corresponding lever stroke from 0a to 10g, the engine rotation speed is read via the rotation sensor 5, and the pressure P of the pressure oil discharged from the pump 2 is read via the pressure sensor 8. Next, the process moves to step S2, and the required flow rate of the drive body (arm, packet, etc.) related to the corresponding operating lever, which is set by the required flow rate setting means illustrated in FIG. 2, is read.

Next, as shown in step S3, the first calculation means performs calculation to add these required flow rates to obtain a total value QL.

Next, the process moves to step S4, and the second calculating means calculates the pump flow IQ from the pressure P detected by the pressure sensor 8 and the PQ left curve of the PQ left curve determining means illustrated in FIG. Next, the process moves to step S5, and the third calculating means calculates the pump tilt angle θ from the pump flow IQ obtained in step S4 and the engine rotation speed N detected by the rotation sensor 5, that is, θP=Q/N. Let's do it.

Next, the process moves to step S6, and the first comparing means determines the pump flow rate Q.
A comparison is made between QL and the total required flow rate QL.
If the pump flow rate Q is smaller than the total required flow rate QL, the engine speed is in a low (unpossible) state, that is, it is in a saturated state, and the first output unit calculates the engine speed using the third calculation means. <t, which corresponds to the pump tilt angle θ,
J5 is output to the regulator 3, and a signal corresponding to the maximum rotation speed B is output to the rotation speed control means. As a result, the engine 1 reaches its maximum rotation, and the pump 2 reaches its tilt angle θ.

to discharge pressure oil. After completing this step S7, the process returns to the beginning.

Further, when it is determined in step S6 that the pump flow iQ is equal to or greater than the total required flow rate QL, the engine speed can be lowered, and the process moves to step S8. In this step S8, the fourth calculation means calculates the required tilt angle θ from the reference rotation speed A and the total required flow rate QL, that is, θ
= Perform QL/A 0 Next, the process moves to step S9, where the second comparing means compares the maximum tilting angle θff1aX of the pump 2 set by the maximum tilting angle setting means with the above-mentioned required tilting angle θ. The maximum tilting angle θwax is the required tilting angle θ
In the above cases, the process moves to procedure SIO. In this step S10, the second output section outputs a signal corresponding to the required tilt angle θ obtained by the fourth calculation means to the regulator 3, and outputs a signal corresponding to the reference rotation speed A to the rotation speed control means. do.

As a result, the engine 1 rotates at a reference rotation speed A lower than the maximum rotation speed B, and the pump 2 discharges pressure oil at a tilt angle θ. After completing step SIO, return to the beginning.

In addition, in step S9 described above, the maximum tilt angle θm of the pump 2 is
When it is determined that ax is smaller than the required tilt angle θ,
Proceeding to step Sll, the fifth calculation means performs a calculation to determine the required rotation speed Na from the maximum tilt angle θmax and the total value QL, that is, Na = Q t /θmax. Next, the process moves to step S12, and the third output section outputs a signal corresponding to the maximum tilt angle θl1lax to the regulator, and outputs a signal corresponding to the required rotation speed Na to the rotation speed control means. As a result, the engine l has a maximum rotational speed B
The pump 2 rotates at a required rotational speed Na lower than , and discharges pressure oil at the maximum tilt angle θl1lax. After completing step S12, return to the beginning.

FIGS. 5(a) and 5(b) show the pump tilting angle characteristics corresponding to the boom and arm required flow characteristic line 26 shown in FIG. 5(a) when one driving body is operated alone. Line 33 (
FIG. 3 is a diagram showing a motor (engine) rotation speed characteristic line 34 (drawn by a solid line);

As shown in FIG. 5(b), in this embodiment, for example, when operating either the boom or the arm independently, the stroke of the corresponding boom operating lever 10a or arm operating lever 10b reaches a predetermined zero point. Until it reaches
This corresponds to the process from step S9 to step SIO in FIG.
However, as the pump type tilt angle, the required tilt angle θ obtained from the reference rotation speed A and the total required flow rate QL (however, in this case, only the required flow rate of one applicable drive body) is expressed as a signal. It is output to the rotation speed control means and regulator 3. Also, operate the corresponding boom /”-10a%
Alternatively, if the stroke of the arm operating lever 10b exceeds a predetermined zero point, steps S9 to Sll in FIG.
This corresponds to the process toward S12, that is, the total value Q of the maximum tilt angle θmax and the required flow rate is set as the engine rotation speed N,
(However, in this case, only the flow rate of one applicable driving body) is determined from Output.

In the embodiment configured in this way, as long as there is a margin in the pump flow ilQ with respect to the total required flow rate QI, the engine rotation is automatically and continuously according to the operation of each operating lever. The number is selected between the reference rotation speed A and the maximum rotation speed B, and the tilting angle of the pump 2 is selected accordingly to be relatively large. For example, the maximum rotation speed B is 20.
0Or, p, m, standard rotation speed A is 140Or, p, m
, then when turning, the tilt angle of pump 2 was only 30% in the past, but in this embodiment, the tilt angle X of pump 2 is Q = 0.3X2000 = x X 1400x
= 0.3 x 2000/1400 = 0.43 = 43 (%), and the pump efficiency improves as shown in Fig. 6.

Similarly, in the case of one-sided travel, conventionally the tilt angle of pump 2 was 50%, but in this embodiment, the tilt angle X of pump 2 is Q = 0.5x2000 = x x1400x =
0.5×2000/1400 =0.71;71(%), and the pump efficiency improves as shown in FIG. 6.

Furthermore, in this embodiment, the engine l is driven so that the engine rotation speed N is a low rotation speed between the reference rotation speed A and the maximum rotation speed B, so that the noise caused by the engine sound can be relatively suppressed. , and the fuel consumption rate characteristic line 32 in FIG.
As is clear from the above, the fuel efficiency is improved compared to the conventional case where the engine 1 is driven at the maximum rotation speed B.

In addition, the optimum engine speed and pump tilting angle are automatically and continuously selected according to the operation of the control lever, so it is possible to perform continuous heavy excavation-to-heavy excavation operation, or between fine operation and heavy excavation. Repeating operations can be performed only by operating the operating lever, and it has excellent operating fluency.

FIG. 7 is an explanatory diagram showing an outline of the overall configuration of another embodiment of the present invention, and FIG. 8 is a flowchart illustrating a processing procedure in a control device provided in the embodiment shown in FIG.

Another embodiment shown in FIG. 7 includes an engine 1, a rotation speed control means including a governor 1a and a motor 1b, a variable displacement hydraulic pump 2, and Rotation sensor 5 that detects the rotation speed of engine 1
It is equipped with However, the pressure sensor provided in the embodiment shown in FIG. 1 is not provided.

Also, similar to the embodiment shown in FIG. 1, the boom cylinder 7
a, an arm cylinder 7b, a packet cylinder 7c, a left travel motor 7d, a right travel motor 7e, a swing motor 7f, and other actuators, as well as a boom directional control valve 6a, an arm directional control valve 6b, and a packet directional control well 6. C% Pressure-compensated flow control valves such as a force travel direction control valve 6d, a right travel direction control valve 6e, and a swing direction control valve 6f, a boom operation lever 10a, and an arm operation lever 1
0b, a packet control lever 10c, a left drive control lever 10d, a right drive control lever 10e, a turning control lever 10f, and an engine lever 11.

Further, the regulator that controls the discharge volume of the variable displacement hydraulic pump 2 includes an actuator 12 that controls the pump tilt angle, and a directional switching valve 13 that controls the drive of this actuator 12. It uses a load sensing method that operates according to the pressure. Note that 14 is an unload valve, and 15 is a relief valve.

The embodiment shown in FIG. 7 is equipped with a control device 9 that controls the switching of each of the directional control valves 6a to 6f and controls the rotation of the engine 1.
The drive units a to 6g, each operating lever 10a to 10r1, engine lever 11, and rotation sensor 5 are connected to this control device 9.

This control device 9 is made up of, for example, a microcomputer having storage, arithmetic, and logical judgment functions, as in the previous embodiment, and incorporates setting means, arithmetic means, comparison means, and output means.

The above-mentioned setting means includes a required flow rate setting means for setting the relationship between the actuator required flow rate and the lever stroke, as in the previous embodiment, and a reference rotation speed that is lower in advance than the maximum rotation speed B of the engine 1 under no load. The pump 2 includes a reference rotational speed setting means for setting a reference rotational speed A at which the number of rotations, for example, the torque reaches a maximum value, and a maximum tilting angle setting means for setting the maximum tilting angle θmax of the pump 2.

Further, the above calculation means includes a calculation means for calculating the total value QL of the required flow rate of each of the above-mentioned actuators, and a calculation means for calculating the required tilt angle θ from the reference rotation speed A and the total value QL of the required flow rate. , calculation means for calculating the required rotation speed Na from the maximum tilt angle θmax of the pump 2 and the total value QL of the required flow rate.

Further, the above-mentioned comparison means calculates the maximum tilt angle θma of the pump 2.
Compare x with the above-mentioned required tilt angle θ.

Further, the output means described above has an output section that selectively outputs either the reference rotation speed A or the required rotation speed Na to the rotation speed control means.

In another embodiment configured in this way, when the engine 1 rotates as the engine lever 11 is operated, the pump 2 is integrally driven. And each operating lever 10
In accordance with the selective operation of 2 to 10f, a signal is output from the control device 9 to the drive section of one of the corresponding directional control valves 63 to 6f, the corresponding directional control valve is switched, and the pump 2 discharges water. The pressure oil is supplied to the corresponding actuator via the corresponding directional control valve, and the driving bodies such as booms and arms related to the corresponding actuator are driven.

For example, in order to operate the swing motor 7f, the operating lever 10f is operated and the swing direction control valve 6f is switched to position a in FIG. 7. Spool opening 6 of valve 6f
ft and acts on the swing motor 7f, but at the same time, the load pressure applied to the swing motor 7f passes through the spool, acts on the spring chamber of the pressure compensation valve 6f+ via the pipe 6f3, and also passes through the check valve. It is fed back to the spring port of the switching valve 13. At this time, when the load pressure increases, spring force and load pressure are applied to the drive part of the pressure compensation valve 6ft, and the flow rate control part of the pressure compensation valve 6f+ is opened to increase the flow rate, and the spool upstream of the direction control valve 6f is side pressure P.

is increased to keep the differential pressure between the pressure P on the upstream side of the spool and the pressure P on the downstream side constant.At this time, at the same time, the switching valve 13 returns the oil in the actuator 12 to the tank to adjust the tilting angle. Increase the discharge amount and make it follow the discharge amount. Conversely, when the load becomes lighter, the flow control section of the pressure compensation valve 6f+ is throttled, and the pressure P on the upstream side of the spool of the directional control valve 6f is lowered to a state equal to the sum of the load pressure and the pressure P on the downstream side of the spool. . At the same time, the pump discharge pressure opens a passage to the actuator 12 of the switching valve 13 and reduces the tilting angle. In this way, the load pressure is constantly detected, that is, load sensing is performed, and the pump discharge amount is controlled to minimize energy loss.

As a result, a flow rate can be supplied to the swing motor 7f regardless of changes in load pressure (in accordance with the operation amount, ie, the stroke, of the operating lever 10f. The same applies to other actuators.

When performing the above-mentioned combined operation of the actuator, for example, combined operation of the arm and the packet, the control device 9 performs the process shown in the flowchart of FIG. 8.

As shown in step S20 in FIG. 8, first read the lever strokes of the operating levers IQb and IOC, and
The engine speed N is read via the rotation sensor 5.

Next, the process moves to step S21, and the corresponding operating levers 10b and 1Qc set by the required flow rate setting means illustrated in FIG.
Then, as shown in step S22, the calculation means adds these required flow rates to obtain a total value QL.

Next, the process moves to step S23, where the calculation means calculates the required tilt angle θ from the reference rotation speed A and the above-mentioned total value QL, that is, θ=QL/A. Next, the process moves to step 324, where the comparison means calculates the maximum tilt angle. Pump 2 set by turning angle setting means
A comparison is made between the maximum tilt angle θwax and the above-mentioned required tilt angle θ, and if the maximum tilt angle θ−ax is greater than or equal to the required tilt angle θ, the process moves to step S25.This procedure S25
Then, a signal corresponding to the reference rotation speed A is outputted from the output section to the rotation speed control means. As a result, the engine 1 rotates at a reference rotation speed A that is lower than the maximum rotation speed B, and the pump 2 returns to the beginning after completing the zero procedure 325 in which the pump 2 discharges pressure oil at the tilt angle θ.

Further, if it is determined in step S24 that the maximum tilting angle θmax of the pump 2 is smaller than the required tilting angle θ, step S24
26, the calculation means calculates the required rotational speed Na from the maximum tilt angle θatax and the total value QL of the required flow rate, that is, Na = Q L /θmax. Next, the process moves to step S27, and the output section outputs the required rotation speed Na. A signal corresponding to the required rotation speed Na is output to the rotation speed control means. Thereby, the engine 1 returns to the beginning after completing the 0 procedure S27 in which the engine 1 rotates at a rotation speed Na lower than the maximum rotation speed B.

In the embodiment configured in this way, as described above, the regulator and pressure compensation valve operate according to the load pressure applied to the actuator by the load sensing method, and the desired flow rate is maintained regardless of changes in the load pressure. The tilting angle of the pump 2 is controlled so as to supply the engine speed to the actuator, and as in the embodiment shown in FIG. Engine 1 is driven so that Therefore, noise can be suppressed, fuel efficiency is improved, and a suitable engine speed is automatically and continuously selected following the operation of the operating lever, providing excellent operability.

〔Effect of the invention〕

Since the hydraulic drive device of the present invention is configured as described above, the pump efficiency is improved and the fuel consumption is improved.Therefore, the hydraulic drive device of the present invention is more economical than the conventional one, and has excellent operability.
Further, noise can be suppressed.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an outline of the overall configuration of an embodiment of the hydraulic drive device of the present invention, Fig. 2 is a diagram showing the relationship between the lever stroke set in this embodiment and the actuator required flow rate, and Fig. 3 is a characteristic diagram showing the relationship between the rotation speed of the prime mover, output horsepower, torque, and fuel consumption rate; FIG. 4 is a flowchart illustrating the processing procedure in the control device provided in this embodiment; FIGS. ) is an explanatory diagram explaining the characteristics when one driving body is operated alone;
is a diagram showing boom and arm required flow characteristic lines, Figure 5 (
b) is a diagram showing the pump tilting angle characteristic line and prime mover rotation speed characteristic line corresponding to the boom and arm required flow rate characteristic line shown in Fig. 5(a), and Fig. 6 is a diagram showing the pressure oil discharged from the pump. A characteristic diagram showing the relationship between pressure P and flow iQ and a pump efficiency curve, FIG. 7 is an explanatory diagram showing an outline of the overall configuration of another embodiment of the present invention, and FIG. 8 is a diagram illustrating the embodiment shown in FIG. It is a flowchart which illustrates the processing means in the control device provided. 1... Engine (prime mover), 1a... Governor, ■b
...Motor, 2...Variable displacement hydraulic pump, 3...
Regulator, 4...Tilt angle sensor, 5...Rotation sensor, 7a...Boom cylinder, 7b...Arm cylinder, 7c...Packet cylinder, 7d...Left travel motor, 7e...・Right travel motor, 7f... Swivel motor, 7g... Breaker, 6a... Directional control valve for boom, 6b... Directional control valve for arm, 6C... Directional control valve for packet, 6d.・・Left travel direction control valve, 6
e... Directional control valve for right travel, 6f... Directional control valve for turning, 6fz... Pipeline, 6g... Directional control valve for breaker, 8... Pressure sensor, 9... Control Device, 10a
...Boom control lever, 10b...Arm control lever, IOC...Packet control lever, 10d.
...Operation lever for left running, lOe...Operation lever for right running, 10f...Operation lever for turning, Log...Operating lever for breaker, 11...Engine lever. Fig. 1 Fig. 2 Shimachi draw 2 Fig. 3 Rotation technique Fig. 4 Fig. 5 (0) (b) Fig. 6

Claims (1)

[Claims] (1) A prime mover, a rotation speed control means for controlling the rotation speed of the prime mover, a variable displacement hydraulic pump driven by the prime mover, a regulator for controlling the discharge volume of the variable displacement hydraulic pump, and this regulator. a regulator control means for controlling the drive of the variable displacement hydraulic pump; and an actuator driven by pressure oil discharged from the variable displacement hydraulic pump;
An operating device that commands the drive of the actuator, and a control device that controls the flow of pressure oil supplied to the actuator from the variable displacement hydraulic pump, and operates the operating device without depending on changes in the load pressure applied to the actuator. In the hydraulic drive device, the hydraulic drive device includes a flow rate control valve capable of supplying a flow rate according to the amount of flow, and a control device that performs switching control of the flow control valve and rotation control of the prime mover, wherein the control device controls the actuator when driving the actuator. a required flow rate setting means for setting a required flow rate of pressure oil; a reference rotation speed setting means for setting the rotation speed of the prime mover to a reference rotation speed lower than the maximum rotation speed under no load; calculating means for calculating a required pump tilting angle from the required flow rate set by the required flow rate setting means and the reference rotation speed set by the reference rotation speed setting means; a comparison means for comparing the maximum tilting angle with the maximum tilting angle, and when it is determined that the maximum tilting angle is smaller than the required pump tilting angle by the comparison between the comparison means, the maximum tilting angle and the required flow rate are determined to be smaller than the required pump tilting angle; and an output means for selectively outputting either the reference rotation speed or the required rotation speed according to the comparison result of the comparison means. Hydraulic drive system.