WO1995003492A1

WO1995003492A1 - Apparatus and method for automatically compensating for dead zone of a hydraulically driven machine

Info

Publication number: WO1995003492A1
Application number: PCT/JP1994/001177
Authority: WO
Inventors: Seiji Kamada
Original assignee: Kabushiki Kaisha Komatsu Seisakusho
Priority date: 1993-07-21
Filing date: 1994-07-19
Publication date: 1995-02-02
Also published as: JPH0735105A

Abstract

An apparatus and method for automatically compensating for a dead zone of a hydraulically driven machine which is capable of easily and precisely detecting a dead zone of an actuator for compensation and improving the trackability, operability, drivability and maintainability of hydraulic equipment. To this end, a detecting means for detecting a dead zone of a flow rate controlling means (10) consists of pressure detecting means (23, 24) for detecting a pressure acting on an actuator (31) or a pump (2), and a judging means for judging the amount of a dead zone consists of a dead zone judging means (50) for judging the dead zone amount of the flow rate controlling means (10) by a signal from the pressure detecting means (23, 24) and a control input instructing means.

Description

Description Automatic dead zone detection device for hydraulically driven machines and automatic dead zone detection method

The present invention relates to a dead zone automatic correction device for a hydraulically driven machine that automatically corrects an output value of a start-up operation when a hydraulically driven machine such as a hydraulic excavator or a crane is automatically controlled by an electromagnetic valve or the like, and a dead zone thereof. It relates to an automatic correction method. Background technology

Conventionally, in hydraulically driven machines such as construction machines, when controlling hydraulic equipment such as work equipment, traveling, turning, etc. by an electric signal, the operating lever etc. is operated and the direction is controlled by an electromagnetic proportional pressure control valve. The changeover valve is switched, the hydraulic oil from the hydraulic source is sent to the factory, the factory is operated, and work is performed by working equipment such as work equipment. During this operation, there is a region where the actuator will not operate unless a signal exceeding a certain value is obtained even if the operation lever is moved, that is, a dead zone. This dead zone is caused by variations in the pressure generated by the electromagnetic proportional pressure control valve, variations in the sliding resistance of the main spool of the directional control valve, and variations in the performance of hydraulic equipment such as the pump discharge amount. Due to these variations, in the dead zone, there are variations in the lifting and lowering operations of a single unit, and in addition, there is variation in the working equipment for each unit of production. For this reason, when it is necessary to perform high-precision automatic control, the position of the dead zone is checked after assembling one unit, one unit, and the car body, and the dead band that differs for each unit It is necessary to add the minute and the added value to be the control command value.

As a conventional technique for automatically detecting the dead zone of the hydraulic drive machine, while gradually increasing the command to the hydraulic drive unit, it is automatically detected by detecting that the rotation change angle of the work equipment etc. exceeds a certain value. (See, for example, Japanese Patent Application Laid-Open No. 4-149604). However, in the conventional method of determining the dead zone using the joint angle sensors described above, as shown in Fig. 12, the detection (R point) is performed a short time after the joint starts moving, and the dead zone is detected with high accuracy. For detection, it is necessary to judge the dead zone region when the change amount Ha of the angular displacement is small, which is difficult. In addition, if the change command value (angle 0a) is increased in order to improve the accuracy of the judgment, there is a problem that the change Ha with respect to the operation amount becomes large and fine adjustment becomes difficult.

On the other hand, in construction machinery in recent years, closed center load sensing systems have begun to be used in hydraulic circuits in order to improve workability and facilitate operability. In this system, the load pressure on the actuator side is transmitted to the pump as load sensing pressure before the valve opens, and the pump pressure automatically rises above the load pressure. Also, it becomes constant without depending on the load of the night. In recent years, in particular, using this system, automation such as high-precision trajectory control of working machines such as straight line excavation and slope excavation has been progressing. At the same time, it is desired to detect a dead zone at the time of factory shipment and to correct the operation command based on the value so that even a beginner including the above system can easily and automatically perform the operation.

As another conventional technique, in a device that performs trajectory control of a robot or the like, a dead zone or the like required for control is determined in advance by nonlinear characteristics and is corrected. For example, as shown in "Dynamic characteristics identification method for manipulators (Transactions of the Society of Instrument and Control Engineers, Vol. 22, N.sub.06, P.63-64.43, JAPAN)" There is a known method in which the torque of the motor is gradually increased from the stationary state of Piyre, and the torque when the motor starts to move in the plus or minus direction is determined from each joint angle sensor signal. That is, the output of the actuator is gradually increased, and the variation of the start value is automatically detected due to a change in the signal of the actuator rotation angle sensor. In addition, in order to determine the start of movement with high accuracy, the slope of the increase in the output command to the actuator is made extremely small, and a slight change in the posture of the work equipment is detected.

However, in such a conventional method, the smaller the change in output, the smaller the amount of change. This requires a high-precision angle sensor such as an encoder used for a robot or the like, which causes a problem that the device becomes expensive. In addition, in the case of a machine such as a construction machine that generates a lot of vibration, if a high-precision angle sensor is used, there is a problem that the angle sensor is broken due to vibration and reliability is reduced. Disclosure of the invention

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and is intended for a hydraulically driven machine, in particular, a working machine, a turning machine, a traveling machine, and the like of a construction machine such as a hydraulic shovel and a crane. It is an object of the present invention to provide a dead zone automatic correction device and a dead zone automatic correction method for a hydraulically driven machine that automatically, easily and accurately detect and correct the output value of the start of operation during control. Aim.

In order to achieve this object, in the first invention according to the present invention, the detecting means for detecting the dead zone of the flow control means is a pressure detecting means for detecting the pressure acting on the actuator or the pump. The judgment means for judging the dead zone amount is an automatic dead zone correction device for a hydraulically driven machine, which is a dead zone judging unit for judging the dead zone amount of the flow rate control means based on signals from the pressure detection means and the operation amount command means. The flow rate control means includes a closed center type switching valve and a pressure compensation valve. The closed center type switching valve may be provided with a restrictor that sets a differential pressure between the pump port and the cylinder port to a predetermined value during operation. Further, at least one pressure detecting means is provided between the switching valve and the actuator or between the pump and the switching valve. Further, the storage means for storing the dead zone amount determined by the dead zone determination means is a non-volatile memory in which a record remains even when the power supply is erased.

According to such a configuration, since the pressure detecting means such as a pressure sensor is used to determine the dead zone, the change command value (angle 0 b) can be reduced as shown in FIG. This makes it possible to detect the flow command value, which is a dead zone, with almost no movement of the work equipment. Moreover, a large change (Hb) can be obtained even if the change command value is small, so that the accuracy of determining the dead zone is improved. In particular, construction machines In the case of hydraulically driven machines such as hydraulic machines, even if there is a large variation in the performance of hydraulic equipment such as hydraulically operated valves and electromagnetic proportional pressure control valves, the dead zone is automatically corrected. When performing multiple operations, multiple factories can be made to cooperate with each other at the same time, without causing lag or jumping out. As a result, in the above-described operations such as the straight excavation and the slope excavation, the accuracy of the excavation flatness is improved, and high reliability is obtained even for a construction machine having much vibration. In addition, the work of detecting the dead zone position of each vehicle after assembling the vehicle becomes easy, and a simple configuration can be achieved by using an inexpensive and low-precision pressure sensor instead of a high-precision angle sensor. Thus, the dead zone can be detected with high accuracy.

In the second invention, the predetermined threshold value for starting the movement of the actuator that is set in advance is a predetermined threshold value based on the pressure, and the detected value is the oil transmission from the pump to the actuator for a night. This is a method of automatically correcting a dead zone of a hydraulically driven machine, which is a detection value based on the side pressure, or the oil discharge side pressure between the tank and the tank. Further, the flow rate control means is a switching valve of a closed center type and having a predetermined pressure difference between the pump circuit and the cylinder circuit during operation, and the predetermined threshold value based on the pressure is: This is a predetermined pressure difference. Further, the flow control means is an open center type switching valve, and the predetermined threshold value based on the pressure is a predetermined threshold value between a pressure acting on the pump during operation and a pressure acting on the actuator during non-operation. The pressure difference. According to such a configuration, the predetermined threshold value and the detection value based on the pressure are obtained, and these are compared and determined to control the dead zone, so that the same operational effects as those of the first invention can be obtained. Further, the same advantageous effects can be obtained in a hydraulically driven machine in which the flow control means uses a closed center type switching valve or an open center type switching valve. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an explanatory diagram of a dead zone automatic correction device for a hydraulic drive machine according to a first embodiment of the present invention, and FIG. 2 is a detailed description of a control device of a dead zone automatic correction device for a hydraulic drive machine according to the present invention. Fig. 3 is a flowchart showing the operation of the first embodiment. Fig. 4 is a chart showing the relationship between the spool movement amount and the spool opening area of the metering advance circuit for explaining the first embodiment. FIG. 6 is a schematic explanatory view of a working device having a plurality of cylinders in one embodiment, and FIG. 6 is a chart showing a relationship between a spool movement amount and a spool opening area of a meter leading circuit for explaining the first embodiment; 7 is an explanatory view of a device for automatically correcting a dead zone of a hydraulically driven machine according to a second embodiment of the present invention, FIG. 8 is a chart showing the relationship between the spool operation amount and the pressure of the second embodiment, and FIG. FIG. 10 is an explanatory view of a dead zone automatic correction device of a hydraulically driven machine according to a third embodiment, FIG. 10 is a table showing a relationship between a spool operation amount and pressure of the third embodiment, and FIG. 11 is a pressure sensor according to the present invention. Relationship between command value of change in use and amount of change in pressure Table showing, 1 2 is a table showing the relation between the command value and the angle of the change amount of the change in the angle sensor used in accordance with the prior art. BEST MODE FOR CARRYING OUT THE INVENTION

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a dead zone automatic correction device and a dead zone automatic correction method for a hydraulic drive machine according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of a first embodiment of an automatic dead zone detecting device for a hydraulically driven machine according to the present invention, in which a variable displacement hydraulic pump 2 (hereinafter referred to as a variable pump 2) is driven by a driving device 1 such as an engine. Is driven, and the pressure oil from the variable pump 2 enters a closed center type switching valve 10 connected by a pipe 3. The switching valve 10 is constituted by a spool valve (not shown), a spool is inserted into the valve body in a pivotally tight manner, and springs 11 are provided on both end surfaces of the spool. This switching valve 10 holds the spool at the neutral position when normal operation is not performed. At both ends of the spool, pilot chambers 13, 14 for sliding the spool in proportion to the oil pressure are provided. Pilot chambers 13 and 14 are connected to electromagnetic proportional pressure control valves 15 and 16 (hereinafter referred to as electromagnetic pressure valves 15 and 16) by piping, respectively. Also, the electromagnetic pressure valves 15 and 16 are connected to the control device 50, and in normal operation, a command from the control device 50 which receives a signal corresponding to the operation amount of the operation lever device (not shown) is provided. To Accordingly, the pressure from the fixed displacement pump 4 is controlled and sent to the pilot chambers 13 and 14.

The switching valve 10 is connected to the operating lever device via the electromagnetic pressure valves 15 and 16 and the control device 50. The spool valve of the switching valve 10 moves in response to a command corresponding to the operation amount of the operation lever device. With this movement, the pressure oil from the variable pump 2 is sent to the cylinder (actuator) 31 of the working device 30 via the pipes 21 and 22 connected to the switching valve 10 '. In particular, return oil from the cylinder 31 is returned to the tank 5 via the pipes 21 and 22. Pressure sensors (pressure detecting means) 23 and 24 are provided in these pipes 21 and 22 to measure the pressure acting on the cylinder 31 and output the pressure signal to the control device 5 as a pressure signal. Sent to 0.

The working device 30 includes a cylinder 31, an arm 32, a baguette 33, links 34, 35, and a boom 37 (see FIG. 5). One end of the cylinder 31 is connected to the arm 32, and the cylinder rod 31a at the other end of the cylinder 31 is connected to the baguette 33 via the links 34, 35. ing. Then, by the supply and discharge of oil from the switching valve 10, the baguette 33 is rotated to perform operations such as excavation and earth removal. Further, a predetermined holding pressure for holding the baguette 33 and the links 34, 35, etc. is applied to the cylinder 31 in a normal work or maintenance state.

In the above example, the number of the cylinders and links of the working device 30 is limited, but the working device 30 may be composed of a plurality of cylinders and links. As an example, FIG. 5 shows a schematic explanatory diagram of a working device provided with a boom 37 and a boom cylinder 31A in addition to FIG. The boom cylinder 31A, the variable pump 2, and the control unit 51 are connected in parallel by a hydraulic circuit, piping, and the like, similarly to the cylinder 31 in FIG. The main components are a switching valve 10 A, a pilot chamber 13 A, 14 A, a solenoid pressure valve 15 A, 16 A, and a pressure sensor 23 A, 24 A. .

Next, in FIG. 1, pressure compensating valves 25 and 26 are disposed between the switching valve 10 and the cylinder 31. When two or more cylinders 31 and 31A (see Fig. 5) are operated simultaneously, these pressure compensating valves 25 and 26 are connected to the respective cylinders 31 and 31A. Regardless of the magnitude of the load, the flow according to each operation command is controlled to be distributed to the cylinders 31 and 31A. Further, the switching valve 10 sends the pressure oil of the variable pump 2 to each of the cylinders 31 and 31A, and the pressure applied to the pressure compensation valves 25 and 26 to the check valve 27. To the servo valve 2a of the variable pump 2, and discharges the variable pump 2 so that the discharge pressure of the variable pump 2 becomes a predetermined pressure with respect to the pressure applied to the pressure compensation valves 25 and 26. Controlling the amount. In the case where a plurality of switching valves 10 and 10 A (see FIG. 5) are used in the above, the pressure compensating valves 25 and 26 attached to each cylinder and the servo valve 2 a of the variable pump '2 are used. Or the unload valve 6 has the highest pressure acting on each cylinder, either the check valve 27 of the switching valve 10 or the check valve (not shown) of the switching valve 1OA. Therefore, it is guided and acted as pilot pressure.

The unload valve 6 disposed on the pipe 3 from the variable pump 2 unloads the pressure applied to the variable pump 2 to a predetermined low pressure when the switching valve 10 is neutral, and is higher than the load during operation. The pressure corresponding to the load is sent to the cylinder 31 while maintaining a predetermined pressure difference.

The control device 50 includes a control unit 51 including a controller and the like, and a dead zone detection start switch 52. As shown in FIG. 2, the control unit 51 compares the AZD converter 51 a that converts the signals from the pressure sensors (pressure detecting means) 23 and 24 with the initial value storage unit 51 b, Unit 51 c, an output adder 51 d, a DZA converter 51 e for converting a signal from the output adder 51 d, and a dead zone position storage unit comprising a non-volatile memory for storing a dead zone position. 5 and 5 are provided. Non-volatile memory includes EE PROM (ROM that can be electrically erased and written), NV-RAM (abbreviation of nonvolatile RAM, integrated type of EE PROM and RAM), and dead zone information such as IC power supply. You can use a memory member.

In such a configuration, the operation will be described in detail. As an example, a case where pressure sensors 23 and 24 are disposed between the cylinder 31 and the switching valve 10 to detect a dead zone current will be described. In the following, as an example of detection, baguette 33 is tilted back Detect the dead band current to move to the side (the current command value to the electromagnetic pressure valves 15 and 16 when the bucket 33 just starts to move to the tilt side). This will be described with reference to FIGS.

The control unit 51 serving as a dead zone determining means receives a stop signal from the dead zone detection start switch 52 and receives a pressure sensor disposed between the switching valve 10 and the tilt back side of the cylinder 31. 23 The pressure signal of 3 is input via the AZD converter 51a and stored in the initial value memory 51b as the pressure initial value P0 (step 1551). Here, the stored initial pressure value P 0 is a static holding pressure for the cylinder 31 to hold its own weight of the baguette 33.

Subsequently, a flow command at a level at which the work machine does not move is sent to the electromagnetic pressure valves 15 and 16 for the flow control means. In this detection example, the microcurrent command I is output via the DZA converter 51e to the electromagnetic pressure valve 16 that operates the baggage 33 on the tilt side (step 1522). Also, the detected pressure P from the pressure sensor 23 is converted into an AZD and input (step 1553).

By increasing the current command I, the spool starts to open, the discharge oil of the variable pump 2 flows into the cylinder 31, the cylinder pressure rises above the holding pressure, and the cylinder 31 starts to move. However, the detected pressure P becomes larger than the initial pressure value P0. That is, when gradually increasing the current command value I, the difference between the serial Sunda pressure P and the pressure initial value P o is, first predetermined pressure threshold厶P (e.g., 5 K g Z cm ²⁾ Yue The current command value at that time is the dead band current value of the hydraulic circuit to be obtained.

Therefore, it is determined whether or not the difference between the detected pressure P and the initial pressure value P 0 is larger than a predetermined pressure threshold Δ Δ (step 154). If the difference is not large, the current The value obtained by adding the predetermined minute current ΔI to the output current command I is defined as a new current command I.Steps 15 and subsequent steps are performed until the pressure difference becomes larger than the predetermined pressure threshold Δ Δ. repeat. If this difference exceeds a predetermined pressure threshold value ΔP, it is determined that the spool has opened, and the current value I at that time is set as the dead zone current of the switching valve 10 (step 1555). When the dead zone current value can be detected, the command to the electromagnetic pressure valve 16 is returned to zero. Step 1 5 6) · Finish. Here, the pressure threshold Δ Δ may be set by testing in advance how the cylinder pressure fluctuates when the bucket 33 moves from the predetermined posture to the tiltback side.

Next, in the relationship between the spool opening area and the amount of spool movement shown in FIG. 4, the side flowing into the cylinder from the pump (hereinafter referred to as the meter-in side m) returns from the cylinder to the tank side (hereinafter referred to as the meter side). In the case of a hydraulic circuit that opens earlier than the above, it is sufficient to detect a change in pressure on the meter-in side m and determine the dead zone current value as in the above embodiment. -Further, as shown in FIG. 6, in the hydraulic circuit in which the meter valve precedes, the dead zone current value may be determined by measuring the pressure not on the meter-in side ma but on the meter-out side na. That is, in the case of the pre-measurement circuit in the above embodiment, in steps 151 and 153 (see FIG. 3), the pressure is detected by the pressure sensor 124 on the meter-out side na, and The example may be performed similarly. In this case, in particular, the cylinder 31 is set to the maximum pushing side as the initial posture of the work machine, and the high pressure is confined in advance to the cylinder bottom side, which is the meter-out side. From this state, the detection of the dead zone current is performed. Good to start. That is, the meter-out side opens before the meter-in side opens, and the closing pressure is instantaneously released to the tank 5, so that the detected pressure P greatly changes instantaneously, and good detection becomes possible.

That is, in the above-described method of detecting a change in the closing pressure on the meter gate side when detecting a dead zone current of a hydraulic circuit having a response time delay to a command current (for example, construction machinery), the pressure sensor 23 is detected at the moment of opening. Since the signals of (1) and (2) greatly change, detection can be performed with a low-precision pressure sensor. In addition, the amount of increase in the current command value to the electromagnetic pressure valves 15 and 16 per unit time is not affected by the response delay of the switching valve 10 even if it is extremely small. The dead zone current value can be detected as described above. Further, in the above-described bucket dead zone detection example, the following may be performed. First, when the dead zone detection start switch 52 is switched, the control unit 51 sends a signal for the baggage 33. Sends a command to the electromagnetic pressure valve 15 or 16. With this command, the baguette cylinder 31 is automatically pressed in advance to the most pushed position or the most retracted position. As a result, at the start of the detection, the posture becomes a predetermined posture, and it becomes possible to set a somewhat large closing pressure. When a command is issued to move the bucket 33 in the direction opposite to the pressing direction, the above-described closing pressure is released immediately before the bucket 33 starts to move, so that the dead zone can be accurately detected. . In addition, the measurement posture is automatically obtained and the detection work becomes easy. Here, it is determined whether or not the cylinder 31 has reached the above-mentioned predetermined posture by detecting the cylinder pressure and continuously issuing a command from the electromagnetic pressure valve 15 or 16 until the cylinder pressure becomes the relief pressure. Operation is good. In particular, it is effective to automatically generate the confining pressure in the cylinder as the initial posture when detecting from the confining pressure change on the meter port side.

The automatic dead zone correction device and the dead zone automatic correction method for the hydraulic drive machine according to the present embodiment are as described above. Therefore, in construction machinery, etc., even if there is a large variation in the performance of hydraulic equipment such as switching valves, the dead zone area is automatically detected, reducing the amount of sunset lag and following hydraulic equipment in multiple operations. Operability is also improved, and operability is improved. In addition, if the mode that performs automatic dead zone correction is selected and activated from normal manual operation, the dead zone area is automatically corrected, making it easy to adjust the dead zone position for each unit after the vehicle is assembled. In addition, the adjustment time will be shortened and the maintainability will be improved. In addition, since the dead zone can be adjusted with a low-cost, low-precision pressure sensor, high reliability can be obtained even for machines with high vibration, such as construction equipment.

A second embodiment of the apparatus for automatically correcting a dead zone of a hydraulically driven machine and the method for automatically correcting the dead zone according to the present invention will be described with reference to the drawings.

FIG. 7 is an explanatory diagram of a second embodiment of a dead zone automatic correction device for a hydraulic drive machine. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In FIG. 7, a pressure sensor 61 serving as a pressure detecting means is disposed in a pipe 3 between the variable pump 2 and a closed center type switching valve 110. Pump discharge pressure is It is sent to the control device 50 as a discharge pressure signal 61 a from the force sensor 61. A spool is pivotally inserted into the valve body (not shown) in the switching valve 110, and a panel 11 and proportional solenoids 112, 113 are provided on both end surfaces of the spool. The spool is normally held in the neutral position SO when no operation is performed. The proportional solenoids 112, 113 are connected to the controller 50. Normally, the switching valve 110 is in the neutral position SO, and the variable pump 2 is loaded with a predetermined pressure Pa by the operation of the unload valve 6 (set pressure of the panel 6a). In this state, the variable pump 2 discharges a predetermined small oil amount with a small loss horsepower by the servo valve 2a. The spool is opened at the operating positions SI and S2 of the switching valve 110, and in this state, the pressure between the spool and the pressure relief valves 25 and 26 (hereinafter referred to as LS pressure) is increased. The unload valve 6 and the pump servo valve 2a are reached via the check valve 27.

In the pump sump valve 2a, the discharge pressure of the variable pump 2 is controlled to be higher than the LS pressure by a predetermined pressure (the action of the throttle W of the switching valve 110 having a variable throttle function). The discharge rate of the variable pump 2 is 增ぇ, which increases the LS pressure at the same time. Also, in the unload valve 6, the oil released to the tank is automatically throttled by the LS pressure, so that at the same time as the spool is opened, the pump discharge pressure rises above the cylinder pressure. Before the spool is opened, the pump discharge pressure is maintained at a constant unload pressure because the LS pressure does not act on the unload valve 6 and the pump servo valve 2a.

A case in which a dead zone current is detected in the above configuration will be described. In the following, different points from the first embodiment will be described.

In FIGS. 7 and 8, the dead zone determination means receives a start signal from the dead zone detection start switch 52, and uses the pressure sensor 61 to perform AZD conversion using the predetermined pressure Pa of the unload valve 6 as a pressure signal. It is input via the pressure vessel 51a (see Fig. 2) and stored in the initial value memory 51b (see Fig. 2) as the pressure initial value Pa (equivalent to the chip 151 in Fig. 3). As the current command I is gradually increased, the spool starts to open, the discharge oil of the variable pump 2 reaches the unload valve 6 via the check valve 27, and the pump discharge pressure rises between the spool opening and the At the same time, the pressure rises above the cylinder pressure P nc. That is, the current command when the difference between the pump discharge pressure P nd increased by the pump 2 and the initial pressure value Pa becomes larger than a predetermined pressure threshold Δ Ρ (for example, SK g Z cm ² ) for the first time. Let the value be the dead band current value of the hydraulic circuit (corresponding to step 1555 in FIG. 3). As a result, the same effects as in the first embodiment can be obtained in the second embodiment.

Next, a third embodiment of a device for automatically correcting a dead zone of a hydraulically driven machine and a method for automatically correcting the dead zone according to the present invention will be described with reference to the drawings.

FIG. 9 is an explanatory view of a device for automatically detecting a dead zone of a hydraulically driven machine according to the third embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. A spool is pivotally inserted into a valve body (not shown) of the open center type switching valve 210, and springs 11 are disposed on both end surfaces of the spool. This switching valve 210 holds the spool at the neutral position when normal operation is not performed. The oil discharged from the pump 202 enters the switching valve 210 from the pipe 3, and at the neutral position, passes through the spool via the spool 2 and the relief valve 2 1 2 (normally about SK g Z cm ^After passing through ゥ set in the ^second position, return to tank 5. At this time, pressure Pa is acting on pump 202. Also, piping 3 from pump 202 is A main relief valve 21 and a pressure sensor 61 are provided.

The operation in such a configuration will be described with reference to FIG. 9 and FIG. The initial pressure value Pnc of the holding pressure acting on the cylinder 31 is stored in the initial value storage device 51b (see Fig. 2) (corresponding to step 151 in Fig. 3). As the holding pressure, a value obtained by a test or a value at the time when the work machine is operated to be in the initial posture is used.

Next, by gradually increasing the current command I, the spool starts to open, and the pressure of the discharge oil increases in accordance with the opening. That is, the discharge oil pressure of the pump 202 is as shown in FIG. Ascend as shown in 0. When the difference between the pump discharge pressure P ne and the initial pressure value P nc becomes smaller than a predetermined pressure threshold ΔP (for example, 5 kg / cm ² ) for the first time, the current command value at that time is set to the hydraulic pressure. Use the dead band current value of the circuit (corresponding to step 15.5 in Fig. 3).

Also in the third embodiment described above, it is possible to automatically and easily and accurately obtain and correct the output value (dead zone) of the start of the actuary. Industrial applicability

Hydraulic oil that can easily and accurately detect and correct the dead zone in the evening, improve the followability of hydraulic equipment in complex operations, etc., and improve operability, operability, and maintainability. The present invention is useful as an automatic dead zone detecting device for a driving machine and a method for automatically detecting the dead zone.

Claims

The scope of the claims

1. Flow control means such as a direction switching valve having a dead zone at the time of oil supply switching to the work equipment, while controlling the flow rate of oil from a hydraulic source equipped with a pump and sending the oil to the work equipment operation equipment. An operation amount instructing unit for instructing an operation amount of the flow control unit; a detection unit for detecting a dead zone of the flow control unit; and a determination unit for determining the dead zone amount based on a signal from the detection unit. In the automatic dead band detecting apparatus for a hydraulically driven machine, the detecting unit is a pressure detecting unit that detects the pressure acting on the actuator or the pump, and the determining unit is configured to detect the pressure. A dead zone determining means for determining the dead zone amount of the flow control means based on signals from the control means and the operation amount command means. .

2. The automatic dead zone correction apparatus for hydraulically driven machines according to claim 1, wherein said flow rate control means comprises a closed center type switching valve and a pressure compensating valve.

3. The hydraulic drive according to claim 2, wherein the closed center type switching valve is provided with a restrictor that sets a differential pressure between a pump port and a cylinder port to a predetermined value during operation. Automatic dead zone correction device for machines.

4. The arrangement of the pressure detecting means is characterized in that at least one pressure detecting means is disposed between the switching valve and the actuator or between the pump and the switching valve. The dead zone automatic detection device for a hydraulically driven machine according to any one of claims 1 to 3.

5. The storage unit for storing the dead zone amount determined by the dead zone determination unit is a non-volatile memory that retains a record even when power is turned off. An automatic dead zone correction device for a hydraulically driven machine as described above.

6. The oil from a hydraulic source equipped with a pump is sent to the actuator via the flow control means, and when the working device is operated by the actuator, a predetermined movement which causes the actuator to start moving. A threshold value is set in advance, and a dead zone automatic correction method of a hydraulically driven machine that detects a dead zone region while comparing and judging the predetermined threshold value with a detected value, wherein the predetermined threshold value is a pressure. A predetermined threshold value based on the pressure, and the detection value is a detection value based on an oil-feeding pressure between the pump and the actuator over a period of time or an oil-discharge pressure between the actuating and a tank over time. Characteristic method of automatic detection of dead zone of hydraulic drive machine.

7. The flow rate control means is a switching valve having a closed center type and having a predetermined pressure difference between a pump circuit and a cylinder circuit during operation, and the predetermined threshold value based on the pressure is 7. The method for automatically detecting a dead zone of a hydraulically driven machine according to claim 6, wherein the pressure difference is a predetermined pressure difference.

8. The flow control means is an open center type switching valve, and the predetermined threshold value based on the pressure is a pressure acting on the pump during operation and a pressure acting on the pump when not operating. 7. The method for automatically correcting a dead zone of a hydraulically driven machine according to claim 6, wherein the pressure difference is a predetermined pressure difference from the pressure to be applied.