JPH02199301A - Hydraulic driving device for inertial body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic drive device for an inertial body that uses pressure oil to drive an actuator that drives the inertial body.

[Conventional technology]

2. Description of the Related Art Machines that use pressurized oil to drive a member to perform a desired operation are used in many fields.

An example of such a machine is a hydraulic excavator. A hydraulic excavator is equipped with one or more hydraulic pumps, and the pressure oil discharged from the hydraulic pumps is used to control the boom cylinder, arm cylinder,
Actuators such as the packet cylinder, swing motor, and left and right travel motors are driven. A flow control valve is provided between each of these actuators and the hydraulic pump, and the flow control valve is controlled by the operator arbitrarily operating the control lever of each actuator provided in the driver's seat of the hydraulic excavator. Acting accordingly, the direction and flow rate of the flow of pressure oil from the hydraulic pump to the actuator is controlled, which in turn controls the operation of the actuator, thereby achieving the intended work of the hydraulic excavator.

Various means have been proposed for drive control of such actuators, and one of them is, for example, Japanese Patent Laid-Open No. 60
There is a load sensing system disclosed in Japanese Patent No.-11706. In this load sensing system, during drive control of the actuator, the differential pressure between the hydraulic pressure on the hydraulic pump side of the flow control valve and the hydraulic pressure (load pressure) on the actuator side (differential pressure generated by the metering orifice of the flow control valve) is constantly maintained. In more detail, the variable displacement hydraulic pump is equipped with a means for controlling the hydraulic pump (variable displacement hydraulic pump) to a certain predetermined value. When the operating lever is operated to increase the speed of the actuator in a state in which the actuator is driven by discharging a flow rate, the opening area of the flow rate control valve increases accordingly.

Therefore, the differential pressure inevitably decreases, causing a deviation from the predetermined value. In accordance with this deviation, a command is output to the variable displacement hydraulic pump to increase its tilt angle to increase the discharge flow rate of pressure oil. This increases the amount of oil passing through the flow control valve, increasing the speed of the actuator, and
At the same time, the differential pressure also increases and returns to the predetermined value. In this way, by controlling the variable displacement hydraulic pump so as to always maintain the differential pressure at a predetermined value, the actuator can be driven and controlled in accordance with the operation of the operating lever.

[Problem to be solved by the invention]

The above load sensing system is limited by the input torque control means of the variable displacement hydraulic pump. Within the torque range, the flow rate to the actuator is determined only by the opening degree of the flow control valve, and the speed control of the actuator is limited by the input torque control means of the variable displacement hydraulic pump. This is an extremely excellent means. However, such a load sensing system has disadvantages when driving a load with large inertia (hereinafter simply referred to as an inertial body).

This will be explained below using an example of a swing motor of a hydraulic excavator. A swing motor of a hydraulic excavator is an actuator that rotates an upper revolving body to which a front mechanism is attached and a prime mover, a hydraulic motor, a driver's cab, and other devices are installed, that is, an actuator that drives an inertial body. Therefore, a large pressure is required to start the swing motor, and for this reason, the operator of the hydraulic excavator usually maximizes the amount of operation of the operating lever when starting the swing motor. By the way, in a load sensing system, when the operating amount of the operating lever is maximized, the opening degree of the flow control valve also becomes maximum, and the variable displacement hydraulic pump attempts to supply the flow rate according to this maximum opening degree. Therefore, when the swing motor is accelerated, a power determined by the flow rate corresponding to the maximum opening and the relief valve setting pressure is applied to the swing motor, and the swing motor is accelerated by this power.

For this reason, excessive power is applied to the power transmission mechanism such as gears interposed between the upper revolving body and the rotation motor, which has an adverse effect on the power transmission mechanism by reducing the life of the ring.
Furthermore, surplus flow other than the flow actually flowing into the swing motor flows out into the tank via the relief valve, causing power loss.

To prevent such inconvenience in the load sensing system, it is possible to limit the input torque of the variable displacement hydraulic pump. If this is done, the power distributed to each actuator will be reduced and the working capacity will be reduced, so it cannot be adopted at all.

The above-mentioned disadvantages are not limited to swing motors of hydraulic excavators, but always occur in hydraulic actuators that drive inertial bodies in various types of hydraulic machines.

The purpose of the present invention is to solve the problems in the above-mentioned prior art,
In hydraulic equipment that uses a load sensing system, the inertial body oil can prevent excessive power from being distributed to the actuator that drives the inertial body, and can also prevent shortening of the life of the mechanism. , to provide a positive drive device.

[Means to solve the problem]

In order to achieve the above object, the present invention includes an inertial body, a hydraulic actuator that drives the inertial body, a hydraulic pump that supplies pressure oil to the hydraulic actuator, and a switching valve that controls the drive of the hydraulic actuator. A hydraulic drive device comprising differential pressure control means for controlling the pressure difference across the flow rate control throttle of the switching valve to a predetermined set value, Opening control means for changing the opening of the switching valve when a switching command is output to the switching valve based on a predetermined speed characteristic until it reaches a value corresponding to the command value of the switching command. The hydraulic actuator is configured to limit the power applied to the hydraulic actuator to a predetermined value or less.

[Effect]

In a hydraulic actuator that drives an inertial body, when a switching command is output to the switching valve that controls its drive, the opening of the switching valve is not immediately set to the command value of the switching command, but at a predetermined speed. The opening degree is gradually changed, and finally the opening degree is set to the command value.

〔Example〕

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a hydraulic circuit diagram of a hydraulic drive system for a hydraulic excavator according to an embodiment of the present invention. In the figure, 1 indicates a pressure oil supply mechanism. This pressure oil supply mechanism 1 includes a variable displacement hydraulic pump 2.3
, their displacement volume variable mechanism (represented by a swash plate)
2a, 3a, a hydraulic cylinder 4 that drives each swash plate 2a, 3a, a control valve 5 that controls input torque, and a control valve 6 that controls the load sensing system.

7 is a pilot pump, and 8 is a relief valve that defines the maximum pressure in the circuit of the pilot pump 7.

Reference numeral 10 denotes a swing motor of the hydraulic excavator, IOL an operation command signal generator that outputs a signal according to the amount of operation of a control lever (not shown) of the swing motor 10, and 11 a switching valve mechanism of the swing motor 10. The switching valve mechanism 11 is an overload relief valve 13a.

13b, a flow rate control valve 12, and an adjustment valve 14. 15 is the boom cylinder of the hydraulic excavator, 15L
Reference numeral 16 indicates an operation command signal generator that outputs a signal according to the operation amount of an operation lever (not shown) of the boom cylinder 15, and 16 indicates a switching valve mechanism of the boom cylinder 15. Switching valve mechanism 1
6 is the same as the switching valve mechanism 11, a flow control valve 17, overload relief valves 18a, 18b, and a regulating valve 19.
It is made up of. 20 is a shuttle valve that selects a high pressure among the load pressures of the swing motor 10 and the boom cylinder 15, and 21 is a leaf valve that defines the maximum pressure of the hydraulic circuit of the variable displacement hydraulic pump 2.3. Reference numeral 22 denotes a control device which receives signals from the operation command signal generators 10L and 15L and controls the opening degree of the flow rate control valves 12.17 based on the signals, and is composed of a microcomputer.

Next, a flowchart showing the operation of this embodiment in FIG.
This will be explained with reference to the opening degree change speed characteristic diagram shown in FIG. 3 and the driving pressure characteristic diagram shown in FIG. 4. Swivel motor lO
When the operation lever is operated, a signal is output from the operation command signal generator 10L according to the amount of operation, and based on this signal, the control device 22 drives the flow rate control valve 12 to a predetermined opening degree.

The operation of this control device 22 will be described later. When the flow rate control valve 12 opens, the variable displacement hydraulic pump 2 is connected to the swing motor 10.
, 3 are supplied, and the swing motor 10 is driven.

The boom cylinder 15 is also driven by a similar operation.

In driving such a hydraulic actuator, the control valve 5 controls the input torque by introducing the discharge pressure of the variable displacement hydraulic pump 2.3 to limit the input torque from exceeding a certain set value. 6 is a variable displacement hydraulic pump 2, 3
The discharge pressure and the maximum load pressure from the shuttle valve 20 are derived to perform load sensing control. Further, the regulating valve 14 has a function of adjusting the deviation in the flow rate of pressure oil due to the magnitude of the load pressure when a complex operation is performed. Since the above operation is well known, detailed explanation will be omitted.

Here, the operation of the control device 22 when a command signal is output from the operation command signal generators 10L, 15L will be explained. The control device 22 first reads these command signals (
Step S1) in the flowchart shown in FIG.
Outputs a drive signal according to the command signal output from L,
The flow rate control valve 17 is set to an opening degree according to the drive signal. Thereby, the boom cylinder 15 is driven at a speed corresponding to its opening degree.

On the other hand, the control device 22 executes control to avoid applying excessive power to the swing motor 10 as described above. This control is based on the following idea. That is, now, the moment of inertia of the inertial body is J, the rotational angular velocity of the upper rotating body of the hydraulic excavator is ω, and the driving pressure is P.
When the capacity of the swing motor 10 is D and the flow rate to the swing motor 10 is Q, the following equation holds true.

dt Here, since ω=Q/D, 1)"dt. Equation (2) controls the pressure P applied to the swing motor 10 by adjusting the rate of change over time of the flow rate Q (dQ/dt). This indicates that the control device 22 can:
By controlling the opening degree of the flow rate control valve 12 in a time-functional manner, the rate of change over time of the flow rate supplied to the swing motor 10 is adjusted, thereby controlling the power applied to the swing motor 10.

The processing from step 82 in the flowchart shown in FIG. 2 is as follows:
This is a process for performing such control.

Next, this process will be explained.

When the signal from the operation command signal generator 10L is read in step S, the valve opening degree of the flow rate control valve 12 is controlled using this signal as a control start signal.

That is, first, the valve opening change rate is determined from the previous command value of the valve opening for the flow control valve 12 (command value obtained by step S, which will be described later) (step S).

FIG. 3 shows the characteristics of the valve opening change speed with respect to the valve opening command value. Such characteristics are obtained by a function generator included in the control device 22 or stored in a memory device. As is clear from the solid line in FIG. 3, the valve opening rate change rate is set to a maximum value when the valve opening command value ranges from 0 to a certain value, and thereafter decreases linearly. This is because this is the first process when starting up the swing motor 10.

The previous valve opening command value was O.

Next, in order to output the first valve opening command value to the flow rate control valve 12, this is calculated as the current valve opening command value (step S3). That is, the current valve opening command value is obtained by adding (opening degree change speed x ΔT) to the previous valve opening command value. In this case, the previous valve opening command value is 0, the opening change speed is the value obtained by the processing in step St, and ΔT is the time (time step) required for one round of the processing procedure. The obtained current valve opening command value is compared with the maximum valve opening value of the flow control valve 12 (step S9).
If the current valve opening command value has not reached the maximum valve opening value of the flow rate control valve 12, the process proceeds to step S.

Next, the current valve opening command value is Step S.

It is compared with the value corresponding to the command signal of the operation command signal generator 10L read in. If the current valve opening command value has not reached the value corresponding to the command signal, the current valve opening command value obtained in step S is output as the valve opening command value of the flow control valve 12 ( Step S6). Then, the process returns to step S1 again, and the steps S, to S& are repeated.

By repeating the above process, the valve opening command value of the flow control valve 12 gradually increases regardless of the operating amount of the operating lever of the swing motor 10, and the speed of increase is shown in FIG. The speed corresponds to the opening change speed. And step S
S, the current valve opening command value is the operation command signal generator 10L.
When it is determined that the output signal has reached the output signal of Replace the valve opening command value with the opening command value (step S7), and output the replaced valve opening command value to the flow control valve 12 (step S&), that is,
A valve opening command value corresponding to the operation amount of the operating lever of the swing motor 10 is output to the flow control valve 12 . Also, in step S4,
If it is determined that the current valve opening command value has reached the maximum valve opening value of the flow control valve 12, regardless of the current valve opening command value obtained in step S, This is replaced with the maximum valve opening value (procedure SS), and this maximum valve opening value is output to the flow rate control valve 12 (procedure S&).

Through the above control, the driving pressure of the swing motor 10 is controlled by a temporal change in the opening degree of the flow control valve 12. here,
In load sensing control, since the valve opening degree is proportional to the flow rate to the swing motor 10, the swing motor 1
The driving pressure of 0 will be controlled by the flow rate. Fourth
The figure is a characteristic diagram of the driving pressure against the flow rate of the swing motor 10 when the opening degree change speed shown in Fig. 3 is followed, and thereby the power applied to the swing motor 10 is controlled so as not to exceed a predetermined value. It is clear that it can be done.

In this way, in this embodiment, the valve opening of the swing motor is gradually increased at a predetermined opening change rate until the valve opening corresponds to the command value, so the load sensing system is adopted. It is possible to prevent excessive power from being applied to the swing motor even when the rotation motor is in use, which in turn prevents the life of the transmission mechanism from being shortened, and further reduces power loss caused by relief of excess flow. It can be prevented. Furthermore, in hydraulic excavators, work is often performed in which the boom is raised and the upper revolving structure is rotated at the same time, but in this work, the revolving speed of the upper revolving structure is much lower than the boom raising speed. I tend to move too quickly. However, by employing the control means of this embodiment and arbitrarily setting the characteristics of the opening degree change speed, it is possible to appropriately distribute the power, and as a result, both can be driven with good timing.

FIG. 5 is a hydraulic circuit diagram of a hydraulic drive system for a hydraulic excavator according to another embodiment of the present invention, in which the same or equivalent parts as shown in FIG. 1 are given the same reference numerals. The explanation will be omitted. 11' is a switching valve mechanism for the swing motor 10. In this switching valve mechanism 11', poppet valves 12a, .about.12a4 and electromagnetic proportional valves 12b, .about.12b4 correspond to the flow rate control valve 12 shown in FIG. 16' is a switching valve mechanism for the boom cylinder 15. In this switching valve mechanism 16', poppet valves 17a+ to 17a4 and electromagnetic proportional valves 17b1 to 17b4 correspond to the flow rate control valve 17 shown in FIG.

22' is a control device corresponding to the control device 22 shown in FIG. 23 is a swing motor 10 and a boom cylinder 15
This is a restriction provided in a common pilot pipe line that introduces the load pressure of the control valve 6, and the maximum load pressure is applied to the control valve 6 by this restriction 23.

When a command signal is output from the control device 22' to the electromagnetic proportional valves 12b+, 12bt, the poppet valves 12a+, 12at open at an opening degree corresponding to the command signal, and the swing motor 10 is driven. Furthermore, when a command signal is output to the electromagnetic proportional valves 12b5 and 12b4, the poppet valve 1 is opened at an opening degree corresponding to the command signal.
2a3 and 12an are opened, and the swing motor 10 is driven in the opposite direction. The boom cylinder 15 is driven in the same manner. The processing procedure of the control device 22' is as shown in FIG.
This is the same as the processing procedure in step 2, and the rotation motor 10 is
, the control mode of the boom cylinder 15 is also the same, and the same effects as those of the previous embodiment are achieved.

In addition, in the description of each of the above embodiments, the swing motor of a hydraulic excavator was used as an example of the hydraulic actuator.
The invention is not limited to this, and can be applied to any hydraulic actuator that drives an inertial body. Further, if the opening degree change speed characteristic shown in FIG. 3 is made into a hyperbola as shown by the broken line, a better approximation to equal horsepower becomes possible. Furthermore, even better characteristics can be obtained by correcting the above characteristics using the moment of inertia and the pump rotation speed. Furthermore, in each of the above embodiments, an example was shown in which the differential pressure before and after the metering orifice of the flow control valve is controlled by manipulating the pump discharge flow rate. A system may be used in which the differential pressure is controlled by flowing out, or the differential pressure may be adjusted to be a predetermined value larger than the orifice differential pressure finally adjusted by the regulating valves 14 and 19.

〔Effect of the invention〕

As described above, in the present invention, the opening control means allows
Since the opening degree of the switching valve is changed based on predetermined speed characteristics, it is possible to prevent excessive power from being distributed to the hydraulic actuator that drives the inertial body, and the mechanism In addition, when a hydraulic actuator other than the hydraulic actuator is provided and a combined operation with the hydraulic actuator is performed, each hydraulic actuator can be operated appropriately.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic circuit diagram of a hydraulic drive system for a hydraulic excavator according to an embodiment of the present invention, and FIGS. Degree change speed characteristic diagram and driving pressure characteristic diagram, 5th
The figure is a hydraulic circuit diagram of a hydraulic drive device for a hydraulic excavator according to another embodiment of the present invention. 2.3...Variable displacement hydraulic pump, 5,6...
...control valve, 10...swivel motor, IOL,
15L...Operation command signal generator, 12.17.
...Flow control valve, 12a1 to 12a4, 17a+
~17a4...Poppet valve, 12b+~12b
4, 17b, ~17b4... Solenoid proportional valve, 14
．． 19...Adjusting valve, 15...Boom cylinder, 20...Shuttle valve, 22°...
...control device, 23...aperture. Labor time degree 1 Kongi style■

Claims (1)

[Claims] An inertial body, a hydraulic actuator that drives the inertial body, a hydraulic pump that supplies pressure oil to the hydraulic actuator, a switching valve that controls the drive of the hydraulic actuator, and a differential pressure across a throttle of the switching valve that is predetermined. and a differential pressure control means for controlling the pressure to a set value, when a switching command to the switching valve is output, the opening degree of the switching valve is set to a value corresponding to the command value of the switching command. 1. A hydraulic drive device for an inertial body, characterized in that it is provided with an opening control means that changes the opening degree based on a predetermined speed characteristic until a certain value is reached.