JP2006220193A - Pilot control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pilot control device having simple and inexpensive construction for achieving high controllability and responsiveness. <P>SOLUTION: The pilot control device comprises an operation device 1 to be operated by a working device operator for outputting an electric signal corresponding to the control input, a first electrohydraulic conversion valve 2 for outputting first pilot pressure oil of oil pressure corresponding to the size of the input electric signal, a second electrohydraulic conversion valve 3 for outputting second pilot pressure oil of preset pressure when inputting the electric signal, a high pressure selecting valve 5 for selecting either high pressure one of the first pilot pressure oil or the second pilot pressure oil and outputting it as pilot pressure oil for a control valve 6, a cutting valve 4 for cutting off the distribution of the second pilot pressure oil to the high pressure selecting valve 5, and a controller 7 for controlling the distribution of the second pilot pressure oil into the cutting valve 4 in response to the electric signal output from the operation device 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  INDUSTRIAL APPLICABILITY The present invention provides a control suitable for use in controlling a pilot pressure of a control valve that adjusts a flow rate of hydraulic fluid to an actuator that drives a work device in a work machine equipped with a hydraulic drive work device such as a hydraulic excavator Relates to the device.

  2. Description of the Related Art A working machine equipped with a hydraulic drive system working device such as a hydraulic excavator is configured with a hydraulic circuit for driving a working device (for example, a boom device, a stick device, or a bucket device) with hydraulic oil. On this hydraulic circuit, a hydraulic pump that operates with the power of the engine, a hydraulic actuator that drives the working device with hydraulic oil supplied from the hydraulic pump, and a hydraulic circuit that connects the hydraulic pump and the hydraulic actuator are interposed. In addition, a control valve, an operation device for controlling opening and closing of the control valve, and the like are provided.

Generally, the operating device is provided together with an operating lever in the cab chamber of the work machine, and the hydraulic oil supplied to each hydraulic actuator is controlled by controlling the opening of the control valve according to the operating amount of the operating lever. The flow rate is controlled so that the working device can perform a desired operation.
An example of such an operation device for a hydraulically driven work machine is disclosed in Patent Document 1. In the technique described in Patent Document 1, an operation lever that generates a pressure proportional to an operation input, that is, a pilot pressure in the pilot line is used. The control valve can be controlled to be opened and closed by introducing the pressure generated in the pilot line to the pressure receiving portions at both ends of the spool of the control valve (pilot drive control valve).

By the way, when an operating device as described in Patent Document 1 is used, a cab chamber provided with an operating lever and a control valve interposed on a hydraulic circuit are connected by a pilot line that transmits pilot pressure. Therefore, many pilot lines are run on the vehicle, and it is difficult to reduce the number of assembly steps and cost.
Therefore, in recent years, the control lever and the control valve are not connected by a pilot line, but the control lever and the control valve are electrically connected as shown in the block diagram of FIG. Control devices for controlling have been developed.

For example, as shown in FIG. 5, the electric operation lever 1 that outputs an electric signal having a magnitude corresponding to the operation amount, and the electric signal output from the electric operation lever 1 are converted into a pilot hydraulic pressure signal to the control valve 6. By applying the control device including the electro-oil conversion valve 2 to the hydraulic circuit of the work machine, it is possible to simplify the hydraulic line by eliminating the pilot line connecting the cab chamber and the control valve 6. It is like that.
JP-A-9-273180

  As shown in FIG. 5, a control device (hereinafter, also simply referred to as an electro-hydraulic pilot control device) that performs control by converting an input electric signal into a pilot hydraulic signal of the control valve 6, Since the electro-hydraulic conversion valve 2 that outputs the pilot hydraulic pressure signal of the control valve 6 is required to have high controllability, a pressure reducing valve type conversion valve is used. However, in the pressure reducing valve type conversion valve, a slight delay occurs in the response of the control valve 6 to the operation of the electric operation lever 1 due to a slight response delay generated when the electric signal is converted into the pilot hydraulic pressure signal.

  That is, in the electro-hydraulic pilot type control device, the operation lever and the control valve as described in Patent Document 1 are directly connected by the pilot line with a slight loss of time required for transmission and conversion of electric signals. It is more difficult to improve the responsiveness than the above, and it may give the operator a feeling of operation. Therefore, if an electro-hydraulic pilot type control device is used to secure the same responsiveness as that of the conventional one, it is necessary to use an expensive conversion valve with excellent response performance, resulting in high cost.

On the other hand, in the control device as shown in FIG. 5, a method of directly controlling the control valve 6 by an electric signal without using the electro-oil conversion valve 2 is also conceivable. However, in this case, it is necessary to electrically generate a large amount of power that can drive the spool of the control valve 6, so that a separate device for driving the spool is required, which increases the cost.
The present invention has been devised in view of such problems, and an object of the present invention is to provide a pilot control device capable of realizing high controllability and responsiveness with a simple configuration and low cost. .

  In order to achieve the above-mentioned target, a pilot control device according to the present invention (Claim 1) is a hydraulic fluid to an actuator that controls a pilot pressure and drives the working device in a working machine equipped with a hydraulically driven working device. A control valve control device for adjusting a flow rate, which is operated by an operator of the working device and outputs an electric signal corresponding to the operation amount, and according to the magnitude of the input electric signal A first electric oil conversion valve that outputs a hydraulic first pilot pressure oil; a second electric oil conversion valve that outputs a second pilot pressure oil of a predetermined pressure when the electric signal is input; and the first pilot pressure oil; A high pressure selection valve that selects one of the high pressures of the second pilot pressure oil and outputs it as the pilot pressure oil of the control valve, and the second pilot pressure oil that is output from the second electric oil conversion valve To the high pressure selection valve A cut valve capable of blocking the passage, in response to the electric signal output from the manipulation device is characterized by comprising a controller for controlling the flow of said second pilot pressure oil in the cut valve.

For example, when the controller determines that high responsiveness is required by the operator based on the electrical signal, the controller opens the cut valve to flow the second pilot pressure oil, and the operator has high responsiveness. When it is determined that it is not required, the cut valve is closed to block the flow of the second pilot pressure oil (Claim 2).
Further, for example, when the controller detects the start of operation of the operating device based on the electrical signal, the controller determines that high responsiveness is requested by the operator (claim 3).

Further, for example, when the controller detects the electrical signal corresponding to the maximum operation amount of the operating device, the controller determines that high responsiveness is required by the operator (claim 4).
Further, for example, the controller determines that a high responsiveness is required by the operator when the change gradient of the magnitude of the electrical signal is equal to or greater than a predetermined gradient (claim 5).

According to the pilot control device of the present invention (Claim 1), with a simple configuration and low cost, good responsiveness according to the input of the electric signal and good controllability according to the magnitude of the electric signal are realized. it can.
According to the pilot control device of the present invention (Claim 2), it is possible to select a control for improving the responsiveness and a control for improving the controllability according to the operator's request, and it matches the operation state. Control can be performed.

  In addition, according to the pilot control device of the present invention (Claim 3), the operation delay of the actuator at the start of the operation can be eliminated, and according to the pilot control device of the present invention (Claim 4), at the time of the maximum operation. The operation delay of the actuator can be eliminated, and according to the pilot control device of the present invention (claim 5), the operation delay of the actuator during sudden operation can be eliminated.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 4 show a pilot control apparatus according to an embodiment of the present invention. FIG. 1 is a block diagram schematically showing the overall configuration of a hydraulic circuit to which the apparatus is applied, and FIG. It is a graph for demonstrating the effect | action and effect of an apparatus, (a) is a graph which shows the time change of the lever operation amount at the time of electric operation lever operation, (b) is the time of the electric current value output from an electric operation lever. (C), (d) is a graph showing the time change of the pilot pressure output from the electro-hydraulic conversion valve, (e) is a graph showing the time change of the spool stroke of the control valve, and FIG. FIG. 4 is a schematic perspective view showing the overall configuration of a work machine to which the pilot control device of the present invention is applied. FIG. 4 is a graph showing the relationship between the current value output from the electric operation lever of the device and the lever operation amount.

FIG. 4 shows a work machine to which a pilot control apparatus as an embodiment of the present invention is applied. The work machine 11 includes a lower traveling body 12 provided with a traveling device (crawler) having an endless track, and an upper swing 13 that is slidably mounted on the upper portion of the lower traveling body 12.
On the upper swing body 13, an engine 10 and a hydraulic pump 9 as a drive source of the work machine 11, a work device 14 for performing various operations such as excavation and lifting, and an operator are mounted on a swing frame that forms the framework. A cab 13 or the like is provided. The work device 14 is composed of independent operation parts such as a boom device, a stick device, and a bucket device, and is provided with a hydraulic actuator (hydraulic cylinder) 8 for driving each operation part. Yes.

FIG. 1 schematically shows the overall configuration of a hydraulic circuit to which the present pilot control device is applied.
First, the hydraulic circuit for operating the work device 14 is provided with a hydraulic pump 9 driven by the power of the engine 10, and hydraulic oil discharged from the hydraulic pump 9 is supplied to each actuator via the control valve 6. 8 is supplied. Here, one of the plurality of actuators 8 is shown as a representative.

  The control valve 6 is configured as a spool valve capable of variably controlling the flow direction and flow rate of the hydraulic oil by switching the position of the stem (flow rate control spool). The switching of the stem position of the control valve 6 and the valve opening degree are set according to the pilot pressure introduced from the pilot line 5a. For example, when the pilot pressure increases, the amount of movement of the stem increases, the opening degree of the control valve 6 is controlled in the opening direction, and the hydraulic oil flow rate from the hydraulic pump 9 to the actuator 8 increases. Further, when the pilot pressure is reduced, the movement amount of the stem is reduced, the opening degree of the control valve 8 is controlled in the closing (throttle) direction, and the hydraulic oil flow rate from the hydraulic pump 9 to the actuator 8 is reduced. ing.

On the pilot line 5a side of the control valve 6, an electric operation lever (operation device) 1, an electro-oil conversion valve (first electro-oil conversion valve) 2, an electro-oil conversion on / off valve (second electro-oil conversion valve) 3, hydraulic pressure A cut valve (cut valve) 4, a high-pressure selection valve 5 and a controller 7 are provided.
The electric operation lever 1 is operated by an operator of the work machine 11 and outputs an electric signal corresponding to the operation amount as an index of the operation amount of the actuator 8.

  Here, as an electric signal corresponding to the operation amount of the electric operation lever 1, a current value (current magnitude) A is output in a correspondence relationship as shown in FIG. That is, the current value that is output is 0 when the electric operation lever 1 is not operated, and a larger current value is output as the operation amount of the electric operation lever 1 increases, and the electric operation lever 1 becomes full. When operated, the current of the current value A1 is output. The output current value A is input to an electro-oil conversion valve 2, an electro-oil conversion on / off valve 3 and a controller 7, which will be described later.

The electric oil conversion valve 2 outputs pilot pressure oil (first pilot pressure oil) having a pressure corresponding to the magnitude of the current value A input from the electric operation lever 1. The electro-hydraulic conversion valve 2 is generally a pressure reducing valve with good controllability. The pilot pressure oil output here is introduced into a high pressure selection valve 5 described later.
In addition, the electric oil conversion on / off valve 3 supplies pilot pressure oil (second pilot pressure oil) having a predetermined pressure P0 when current is input, regardless of the magnitude of the current value A output from the electric operation lever 1. It is designed to output. The electro-oil conversion on / off valve 3 is generally an on-off valve with good response, and the pressure value of the pilot pressure oil output from the electro-oil conversion on / off valve 3 is output from the electro-oil conversion valve 2. Compared to the applied pressure, the pressure is quickly increased or decreased. The predetermined pressure P0 of the pressure oil output here is set to a magnitude of about 20 to 30% of the maximum pilot pressure output from the electric oil conversion valve 2. The output pilot pressure oil is introduced into a high pressure selection valve 5 described later.

The electro-oil conversion valve 2 and the electro-oil conversion on / off valve 3 are connected in parallel to the pilot line 5a. That is, as shown in FIG. 1, the pilot line 5 a connected to the control valve 6 branches from the high pressure selection valve 5 and is connected to the electro-oil conversion valve 2 and to the electro-oil conversion on / off valve 3. It consists of two lines, the connected line.
The high pressure selection valve 5 selects one of the high pressure pilot oils output from both the electro oil conversion valve 2 and the electro oil conversion on / off valve 3, and serves as a pilot pressure oil for the control valve 8 as a pilot pressure oil. Output to the 5a side. Here, the pressure of the pilot pressure oil output to the pilot line 5a (that is, the pilot pressure) works as a pilot pressure for the stem control of the control valve 6.

The hydraulic cut valve 4 is interposed between the electro-oil conversion on / off valve 3 and the high-pressure selection valve 5 and blocks the flow of pilot pressure oil output from the electro-oil conversion on / off valve 3 to the high pressure selection valve 5. The opening / closing control of the hydraulic cut valve 4 is performed by a controller 7 which will be described later.
Based on the current value A output from the electric operation lever 1, the controller 7 determines whether or not high responsiveness is required by the operator. When it is determined that high responsiveness is required, the hydraulic cut valve 4 is controlled to be opened. When it is determined that high response is not required, the hydraulic cut valve 4 is controlled to be closed. Distribution is cut off.

Specifically, at the start of lever operation when the electric operation lever 1 is operated and the current value A is detected, it is determined that high responsiveness is required. As a result, the pilot pressure oil output from the electro-oil conversion on / off valve 3 flows to the high-pressure selection valve 5 from the start of lever operation.
Further, when a predetermined time d2 elapses after the electric operation lever 1 is operated, it is determined that high responsiveness is not already required. Then, the controller 7 controls the hydraulic cut valve 4 to close so as to block the circulation of the pilot pressure oil output from the electro-oil conversion on / off valve 3 to the high pressure selection valve 5. Thereby, the pilot pressure oil output from the electro-oil conversion on / off valve 3 is circulated to the high-pressure selection valve 5 side only after a predetermined time d2 elapses after the electric operation lever 1 is operated. .

Since the pilot control apparatus according to the embodiment of the present invention is configured as described above, it operates as follows.
First, as shown in FIG. 2A, when the electric operation lever 1 starts to be operated from time t0 by the operator, the current value A as an electric signal output from the electric operation lever 1 is shown in FIG. As shown in FIG. 4, it is 0 until time t0 and starts increasing from time t0. This current value A is output to the electro-oil conversion valve 2, the electro-oil conversion on / off valve 3, and the controller 7.

Next, as shown in FIG. 2 (c), the electro-oil conversion valve 2 outputs pilot pressure oil having a hydraulic pressure P 1 corresponding to the magnitude of the input current value A. Here, since the pressure reducing valve is used for the electro-hydraulic conversion valve 2, the pilot pressure P1 varies so as to follow the change in the current value A from time t1 after the slight response delay time d1 has elapsed. become.
On the other hand, in the electro-hydraulic conversion on / off valve 3, as indicated by a solid line in FIG. 2 (d), the pilot pressure of the predetermined pressure P0 when the current value A is input, regardless of the magnitude of the input current value A. Oil is output. Here, since the on / off valve is used as the electro-oil conversion on / off valve 3, the pilot pressure P2 immediately rises from the time t0 when the current value A is input and reaches the predetermined pressure P0, and the current value A fluctuates. Even if this is done, a certain predetermined pressure P0 is maintained.

On the other hand, the controller 7 determines that a high responsiveness is required at the start of lever operation when the electric operation lever 1 is operated and the current value A is detected, that is, at time t0. That is, the hydraulic cut-off valve 4 is controlled to be opened by the controller 7, and the pilot pressure oil output from the electro-oil conversion on / off valve 3 flows to the high pressure selection valve 5 from the start of lever operation.
Further, when a predetermined time d2 has elapsed from the time t0 when the electric operation lever 1 is operated, the controller 7 determines that a high responsiveness has not already been requested. Then, the hydraulic cut valve 4 is controlled to close, and the flow of pilot pressure oil output from the electro-oil conversion on / off valve 3 to the high pressure selection valve 5 is blocked. As a result, the pilot pressure P2 output from the electro-oil conversion on / off valve 3 is introduced to the high pressure selection valve 5 side only between time t0 and time t3 as shown by the solid line in FIG.

That is, the pilot pressure P1 is output from the electro-hydraulic conversion valve 2 with a response delay d1 in a magnitude corresponding to the fluctuation of the current value A, while the pilot pressure P2 is output from the electro-oil conversion on / off valve 3. It will be output with almost no response delay.
In the high-pressure selection valve 5, one of the high-pressure pilot pressure oils output from the two electro-oil conversion valves 2 and 3 is selected, and the pilot pressure oil for the control valve 8 is supplied to the pilot line 5 a side. Is output. That is, when the pilot pressure P1 output from the electro-hydraulic conversion valve 2 is indicated by a broken line superimposed on FIG. 2D, it is indicated by a solid line from time t0 to time t2 (that is, the pilot pressure P1 indicated by the broken line). Until the pilot pressure P2 intersects), the pilot pressure oil at the pilot pressure P2 is output to the pilot line 5a, and after the time t2, the pilot pressure oil at the pilot pressure P1 is output to the pilot line 5a. Become.

  Accordingly, as shown in FIG. 2E, the spool stroke of the control valve 6 immediately rises from the time t0 when the electric operation lever 1 is operated, and the control valve 6 is operated without delay in response at the start of lever operation. Can be controlled. Further, after time t2, the spool stroke of the control valve 6 is controlled by the pilot pressure P1 output from the electro-hydraulic conversion valve 2, and good controllability can be maintained.

As described above, according to the pilot control device of the present invention, it is possible to achieve a good response according to the input of the electric signal and a good controllability according to the magnitude of the electric signal with a simple configuration and low cost. be able to.
Further, since the operation request by the operator is determined and controlled based on the operation of the electric operation lever 1, the control valve 6 can be controlled without a response delay at the start of the operation that requires high responsiveness. When high responsiveness is not required, conventional control with good controllability using a pressure reducing valve can be performed.

[Others]
Although the embodiments of the present invention have been described above, the present invention is not limited to such embodiments, and various modifications can be made without departing from the spirit of the present invention.
First, in the above-described embodiment, the controller 7 has high responsiveness from the lever operation start time t0 when the electric operation lever 1 is operated and the current value A is detected to the time t3 when the predetermined time d2 elapses. It is determined that it is the requested time, but how to determine the operator's request (in what kind of operation state it is determined that “high responsiveness is required”) Is not limited to this.

  In the above-described embodiment, the magnitude of the pressure oil output from the electro-oil conversion on / off valve 3 (that is, the predetermined pressure P0) is 20 to 30% of the maximum pilot pressure output from the electro-oil conversion valve 2. Although it is set to a magnitude of about, the set value of the predetermined pressure P0 can be arbitrarily set. Further, the controller 7 may be configured to set the predetermined pressure P0.

  For example, when the electric operation lever 1 is fully operated, it may be determined that high responsiveness is required and the hydraulic cut valve 4 may be opened, or from the electric operation lever 1 When the input current value A is equal to or greater than a predetermined current value, it may be determined that high responsiveness is required. In this case, by setting the predetermined pressure of the pressure oil output from the electro-oil conversion on / off valve 3 to be approximately the same as the maximum pilot pressure output from the electro-oil conversion valve 2, the operator is high. The control valve 6 can be controlled without a response delay when a full lever is operated to request responsiveness (when the electric control lever 1 is operated to a maximum).

Further, the operator's request may be determined based on the operation time and operation speed of the electric operation lever 1, and the set value of the predetermined pressure of the pressure oil output from the electric oil conversion on / off valve 3 may be set. You may change arbitrarily.
For example, when the operation speed of the electric operation lever 1 becomes higher than a predetermined speed, it is determined that high responsiveness is required, and the predetermined pressure of the pressure oil output from the electro-oil conversion on / off valve 3 is electrically It is conceivable that the operation lever 1 is configured to be set according to the magnitude of the operation speed. In such a configuration, the quicker the operation by the operator, the larger the pilot pressure output from the electro-hydraulic conversion on / off valve 3 can be, and the spool stroke of the control valve 6 can be immediately controlled greatly.

  The controller 7 may be provided with a plurality of responsiveness determination conditions as described above. That is, since various states can be considered for the operation state of the electric operation lever 1 that determines that “high responsiveness is required”, the controller 7 makes a determination using determination conditions corresponding to each operation state. By doing so, it is possible to determine that “high responsiveness is required” when any one of the determination conditions is satisfied, and to make the determination in the controller 7 more accurate. Responsiveness can be improved.

Further, the controller 7 is configured not only to determine whether high responsiveness is required, but also to determine the degree of required responsiveness, that is, how much “high responsiveness” is required. It is also possible to do.
For example, when the operation of the electric operation lever 1 is started and when it is fully operated (when a plurality of responsiveness determination conditions are satisfied), a request for high responsiveness is required. It is considered that the predetermined pressure of the pressure oil output from the electro-oil conversion on / off valve 3 is set larger than the maximum pilot pressure output from the electro-oil conversion valve 2. In this way, by determining the degree of responsiveness required according to the operating state of the electric operation lever 1 and performing control corresponding to the degree, higher controllability and responsiveness can be obtained. Can be realized.

1 is a block configuration diagram schematically showing an overall configuration of a hydraulic circuit to which a pilot control device as one embodiment of the present invention is applied. It is a graph for demonstrating the effect | action and effect of the pilot control apparatus as one Embodiment of this invention, (a) is a graph which shows the time change of the lever operation amount at the time of electric operation lever operation, (b) is an electricity A graph showing the time change of the current value output from the control lever, (c) and (d) are graphs showing the time change of the pilot pressure output from the electro-hydraulic conversion valve, and (e) is the spool stroke of the control valve. It is a graph which shows a time change. It is a graph which shows the relationship between the electric current value output from the electric operation lever of the pilot control apparatus as one Embodiment of this invention, and lever operation amount. 1 is a schematic perspective view showing an overall configuration of a work machine to which a pilot control device of a pilot control device as one embodiment of the present invention is applied. It is a block block diagram for demonstrating the pilot control apparatus as a prior art example.

Explanation of symbols

1 Electric control lever (control device)
2 Electric oil conversion valve (first electric oil conversion valve)
3 Electric oil conversion on / off valve (second electric oil conversion valve)
4 Hydraulic cut valve (cut valve)
5 High Pressure Selection Valve 5a Pilot Line 6 Control Valve 7 Controller 8 Actuator 9 Hydraulic Pump 10 Engine

Claims (5)

In a work machine equipped with a hydraulically-driven work device, a control device for a control valve that adjusts the flow rate of hydraulic oil to an actuator that controls the pilot pressure to drive the work device,
An operation device that is operated by an operator of the work device and outputs an electrical signal corresponding to the operation amount;
A first electro-hydraulic conversion valve that outputs a hydraulic first pilot pressure oil according to the magnitude of the input electric signal;
A second electric oil conversion valve that outputs a second pilot pressure oil having a predetermined pressure when the electric signal is input;
A high pressure selection valve that selects one of the first pilot pressure oil and the second pilot pressure oil and outputs it as a pilot pressure oil of the control valve;
A cut valve capable of blocking the flow of the second pilot pressure oil output from the second electric oil conversion valve to the high pressure selection valve;
A pilot control device comprising: a controller that controls the flow of the second pilot pressure oil in the cut valve in accordance with the electrical signal output from the operating device. When the controller determines that a high responsiveness is required by the operator based on the electrical signal, the controller opens the cut valve to flow the second pilot pressure oil, and the operator requires a high responsiveness. 2. The pilot control device according to claim 1, wherein when it is determined that the second pilot pressure oil is not flown, the cut valve is closed. 3. 3. The pilot control device according to claim 2, wherein the controller determines that high responsiveness is requested by the operator when detecting the start of operation of the operation device based on the electrical signal. 4. The pilot control according to claim 2, wherein the controller determines that a high responsiveness is required by the operator when detecting the electrical signal corresponding to the maximum operation amount of the operating device. apparatus. 5. The controller according to claim 2, wherein the controller determines that a high responsiveness is requested by the operator when a change gradient of the magnitude of the electrical signal is equal to or greater than a predetermined gradient. The pilot control apparatus described in 1.

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