JP2790297B2 - Hydraulic pump torque control method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a torque control method for a hydraulic pump in a hydraulic machine having a hydraulic pump driven by an engine, such as a hydraulic shovel, a crane, or the like.

[Prior Art] In an electronically controlled hydraulic system used for such a hydraulic machine, a controller including a microcomputer controls the entire hydraulic system. In this case, it is determined in advance according to the use mode. The law connexion hydraulic system such as a torque characteristic line PIT ₀ of the engine torque characteristic line EOT and hydraulic pump shown in Figure 3 is controlled in general. Then, a hyperbola in which the product of the total discharge flow rate Q and the discharge pressure P of the hydraulic pump is constant, that is, the pump operates in a known pump output constant curve shape, in other words, the engine torque characteristic line EOT So-called speed sensing control is performed so that the actual engine speed converges to the target engine speed N determined at the intersection with the torque characteristic line PIT ₀ of the hydraulic pump, and the engine and the hydraulic pump operate at maximum efficiency. Often.

[Problem to be Solved by the Invention] However, the above-described pump input torque characteristic line PIT ₀
The pump input torque characteristic line PIT _{0 in} FIG. 4 is expressed by the variation in the accuracy of the components of the torque control means (solenoid valve) of the pump, the variation in the circuit elements of the driver of the controller, the temperature drift, etc. It often shifts (shifts) like PIT ₁ or PIT ₂ . When the torque characteristic line of the pump deviates from the original proper state as in PIT ₁ or PIT ₂ as described above, even if the speed sensing control is performed, this is based on the deviated pump input torque characteristic line. Since the engine is executed, the engine operates at a rotation speed that deviates from the original target rotation speed N, and the operation mode (for example, in the case of a hydraulic shovel, the power mode, which is a heavy excavation mode in which the work machine performs a large amount of work, The engine has a suitable engine efficiency corresponding to the light-excavation mode, which is a light excavation mode with less intensive work, the high-speed traveling mode of the traveling body, the low-speed traveling mode, the crushing work mode in which a crushing breaker is mounted on a work machine, etc. There was a problem that it would not work.

Accordingly, a technical problem to be solved by the present invention is to solve the above-mentioned problems of the prior art, and the purpose thereof is to produce torque control mechanism parts and circuit parts which are inevitable in manufacturing, and temperature drift. It is an object of the present invention to provide a hydraulic pump torque control method capable of performing accurate speed sensing control without deteriorating engine efficiency even if a deviation occurs in the pump torque characteristic line due to the above.

[Means for Solving the Problems] In order to achieve the above object, a torque control method for a hydraulic pump according to the present invention supplies a hydraulic pump that rotates synchronously with an engine and pressure oil from the hydraulic pump via a control valve. Hydraulic actuator, a target engine speed sensor for detecting a target speed of the engine, an actual engine speed sensor for detecting the actual speed of the engine, and pump torque control means for controlling the torque of the hydraulic pump. And a controller that controls pump torque based on output information from the target engine speed sensor, the actual engine speed sensor, and the like, wherein the controller is used to calculate input torque to the hydraulic pump. The target engine speed N from the target engine speed sensor obtained above and the actual engine speed sensor By comparing the actual engine speed Nr from the sensor and shifting the input torque characteristic line of the hydraulic pump in accordance with the engine speed deviation (Nr-N), the hydraulic pump torque is corrected and controlled.

[Operation] As described above, in the present invention, the controller calculates the engine speed deviation (Nr-N) by comparing the target engine speed N with the actual engine Nr, and calculates the engine speed deviation (Nr-N).
N) and the characteristic data of the command torque to the pump are corrected based on the command torque characteristic data (pump input torque characteristic line) to the pump in the past used to calculate the target engine speed N. In other words, the controller executes control to shift (shift) the input (command) torque characteristic line to the pump based on the engine speed deviation (Nr-N), and obtains a new pump input torque characteristic. Data is always updated and held as a learning value. This enables speed sensing control in accordance with the command torque characteristic line held as the learning value, enabling the engine to maintain the target speed without reducing the engine efficiency and maximizing effective use of the hydraulic pump output. It becomes possible.

[Embodiment] Hereinafter, the present invention will be described with reference to one embodiment shown in the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a hydraulic machine having a hydraulic pump driven by an engine, for example, a hydraulic shovel.

In FIG. 1, reference numeral 1 denotes an engine composed of, for example, a diesel engine or the like, and its governor (fuel injection control device) 2
A target engine speed sensor 3 is installed on the governor lever, and an actual engine speed sensor 4 is installed on an appropriate portion such as an engine output shaft. Reference numeral 5 denotes a hydraulic pump driven by the engine 1 and is provided with a torque control means 6 formed of, for example, an electromagnetic valve. Reference numeral 7 denotes a tank. The pressure oil sucked from the tank 7 into the hydraulic pump 5 and pumped up passes through a control valve 8 to actuate each of actuators 9 such as a boom cylinder, an arm cylinder, a bucket cylinder, a swing motor, and a traveling motor. (Hydraulic actuator) to drive an operating member (boom, arm, bucket, swivel, traveling system, etc.) corresponding to the actuator 9. Then, the pressure oil supplied to each actuator 9 passes through the control valve 8 again to the tank 7.
I am coming back to. Reference numeral 19 denotes a hydraulic pressure sensor.

Reference numeral 10 denotes an operation amount input unit, which includes an operation lever and a displacement amount detector that generates an electric signal according to the operation amount of the operation lever, and is supplied with an output signal of the operation amount input unit 10. The controller 11 sends a drive signal to the control valve 8 to drive the actuator 9 corresponding to an amount corresponding to the output value of the operation amount input means 10. The controller 11 controls the entire hydraulic shovel,
It comprises an input processing means 12, an arithmetic control means 13, and an output processing means 14, and the arithmetic control means 13 is mainly constituted by a micro computer.

The input processing means 12 of the controller 11 includes measurement signals from various sensors such as the target engine speed sensor 3, the actual engine speed sensor 4, and the oil pressure sensor 19, and an output signal from the operation amount input means 10. The input processing means 12 performs processing such as amplification, A / D conversion and the like as necessary in the input processing means 12 and sends it to the arithmetic control means 13. Various drive / control signals from the arithmetic control means 13 are output to the torque control means 6, the control valve 8 and the like via the output processing means 14, and the output processing means 14 is provided with a D / A A converter, a driver unit, and the like are provided.

The arithmetic control means 13 of the controller 11 is constituted by a microcomputer, and functionally includes a rotational speed deviation arithmetic unit 15, a torque characteristic correction unit 16, a torque characteristic holding unit 17, a speed sensing control unit 18, and the like. Then, the arithmetic control unit 13 determines that the actuator 9 is operating (that a predetermined load is applied to the hydraulic system), for example, by receiving an operation lever operation signal from the operation amount input unit 10. When this state is recognized, the target engine speed N from the target engine speed sensor 3 (the hydraulic pump 5
Engine speed used to calculate the input torque to the engine)
Is compared with the actual engine speed Nr from the actual engine speed sensor 4 indicating the actual engine speed of the engine 1. If there is a difference between the two, the speed deviation ΔN =
(Nr-N) is calculated.

The torque characteristic holding unit 17 rewritably stores pump input torque characteristic data (corresponding to the pump input torque characteristic line shown in FIG. 3) used for calculating the target rotation speed N. When a value other than “0” is calculated as the above-mentioned rotational speed deviation ΔN = (Nr−N), the torque characteristic correction unit 16 determines the pump torque characteristic line according to this value. Pump input torque characteristic data that is shifted (shifted) by a predetermined amount in the direction is calculated and created, and is updated and recorded in the torque characteristic holding unit 17. That is, as shown in FIG.
Set the pump input torque characteristic line PIT ₀ against, the actual output is decreased to the torque characteristics line PIT _1, since the .DELTA.N <0, the torque characteristic correcting unit 16 characteristic line torque characteristic line PIT ₁
An operation process of returning to PIT ₀ (shifting the torque characteristic line) is executed. Conversely, as the fourth illustrated with respect to the pump input torque characteristic line PIT ₀ that is set, the actual output is decreased to the torque characteristics line PIT _2, since the .DELTA.N> 0, the torque characteristic correcting unit 16 executes arithmetic processing to return the torque characteristic curve PIT ₂ the characteristic line PIT _0. Note that the correction shift speed of the pump input torque characteristic line based on the above-described rotational speed deviation ΔN may be considerably slow, and the retry correction may be gradually performed until the shift value reaches an appropriate value.

The pump input torque characteristic data calculated and corrected by the torque characteristic correction unit 16 based on the rotational speed deviation ΔN is updated and recorded in the torque characteristic holding unit 17, and the speed sensing control unit
It will be reflected in the next and subsequent speed sensing control by 18 mag. That is, the speed sensing control unit 18 drives the torque control unit 6 based on the pump input torque characteristic data stored in the torque characteristic holding unit 17, the actual engine speed Nr, the target engine speed N, the pump discharge pressure, and the like. The control is performed so that Nr converges to N.

Here, the arithmetic control means 13 is actually configured by a microcomputer as described above, and stores various I / O interfaces, a main control program, various fixed data, and the like.
RA that reads and writes ROM, various flags, measurement data, etc.
M, an MPU (microprocessor unit) for controlling the entire system, and the like, and execute, for example, a process shown in FIG. 2 described later by a predetermined program.

FIG. 2 is a flowchart showing an example of a process based on the rotational speed deviation ΔN = (Nr−N) executed by the controller 11 (the arithmetic control means 13).

In the figure, S1 is a step for asking whether or not the operation lever of the operation amount input means 10 is being operated, that is, determining whether or not a load is applied to the hydraulic system. If so, the process proceeds to step S2, and if NO, the process ends. Step S2 is a step for asking whether or not the torque command (pump input torque characteristic line) to the hydraulic pump 5 is the same as the previous time. If YES, proceed to step S3, and if NO, end the process. S3 is the target engine speed sensor 3
Is a step of comparing the target engine speed N with the actual engine speed Nr based on the output of the engine speed sensor 4 and the actual engine speed sensor 4. If N = Nr (speed deviation ΔN = Nr−N = 0), the process proceeds to step S4. , N ≠ Nr (rotational speed deviation ΔN ≠ 0), the flow proceeds to step S5. Step S4 is a step for instructing to maintain the pump input torque characteristic data stored in the recording area (the torque characteristic holding unit 17) as it is. When this step 4 is executed, the process proceeds to step S8. Step
S5 is a step for inquiring whether the rotational speed deviation ΔN is positive or negative. If ΔN <0, the process proceeds to step S6, where ΔN>
If 0, go to step S7. In step S6, shifted by a predetermined amount only pump input torque characteristic line amount in advance Case Histories based on the value of the revolution speed deviation ΔN to the first direction (e.g., the pump input torque characteristic line PIT ₁ of FIG. 4 PI
Back to the T _0), advance followed to step S8. Also, step
In S7, similarly, the pump input torque characteristic line is changed to the second amount by an amount that is case-study based on the value of the rotation speed deviation ΔN.
(For example, the pump input torque characteristic line PIT ₂ in FIG. 4 is returned to PIT ₀ ), and then the step S8 is performed.
Proceed to. In step S8, the speed sensing control is performed, and the process ends.

It should be noted that the above-described processing flow is merely an example, and it goes without saying that various modifications can be made by those skilled in the art without departing from the spirit of the present invention depending on how to set a flag.

[Effects of the Invention] As described above, according to the present invention, even if a deviation occurs in the torque characteristic line of the hydraulic pump due to a variation in component accuracy or a temperature drift which is inevitable in manufacturing, the engine speed deviation value As a result, the pump input torque characteristic line can be corrected to the desired optimum characteristic line, so that accurate speed sensing control can be performed without deteriorating the engine efficiency, and the value of this type of hydraulic machine is enormous.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a hydraulic shovel according to one embodiment of the present invention, FIG. 2 is a flowchart showing an example of processing executed by a controller, and FIG. 3 is an engine output torque characteristic. FIG. 4 is a characteristic diagram showing pump input torque characteristics, and FIG. 4 is a characteristic diagram for explaining a deviation of the pump input torque characteristic line. DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Governor, 3 ... Target engine speed sensor, 4 ... Actual engine frequency sensor, 5 ... Hydraulic pump, 6 ... Torque control means, 7 ... Tank, 8 ...
Control valve, 9 Actuator, 10 Operation amount input means, 11 Controller, 12 Input processing means, 13
... Calculation control means, 14 ... Output processing means, 15 ... Rotation speed deviation calculation unit, 16 ... Torque characteristic correction unit, 17 ... Torque characteristic holding unit, 18 ... Speed sensing control unit.

Claims (1)

(57) [Claims] A hydraulic pump that rotates synchronously with an engine, a hydraulic actuator that is supplied with hydraulic oil from the hydraulic pump via a control valve, a target engine rotational speed sensor that detects a target rotational speed of the engine, An actual engine speed sensor for detecting the actual engine speed, pump torque control means for controlling the torque of the hydraulic pump, and a pump based on output information from the target engine speed sensor, the actual engine speed sensor, etc. A controller for controlling the torque, the controller comprising: a target engine speed N from the target engine speed sensor used to calculate the input torque to the hydraulic pump; The actual engine speed Nr of the hydraulic pump is compared with the input speed of the hydraulic pump according to the engine speed deviation (Nr-N). Torque control method of a hydraulic pump, characterized in that as to shift the click characteristic line is corrected control the torque of the hydraulic pump.