JP2011047414A - Control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device preventing the breakage of pipes and structural equipment in a hydraulic circuit under shocking pressure. <P>SOLUTION: An upstream pressure sensor 17 and a downstream pressure sensor 18 are connected to a second pipe 14 connected downstream of a relief valve 13 for measuring oil pressure inside the second pipe 14 to sense the opening/closing of the relief valve 13. As a result, the maximum flow amount of a pump 10 controlled so that its horsepower is constant is reduced. Thus, when the load of a hydraulic motor 11 is reduced, the amount of oil to be delivered from the pump 10 can be reduced. As a result, no shocking pressure occurs inside the first pipe connected to the pump 10 and the second pipe 14 to be connected to the first pipe 12 via the hydraulic motor 11 to prevent the breakage of the pipes. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control device, and more particularly to a control device that can prevent damage to piping and components of a hydraulic circuit due to shock pressure.

  In a conventional hydraulic control device (control device), the actuator is moved using a pump with constant horsepower control (the amount of hydraulic oil delivered and the pressure applied to the hydraulic oil are inversely proportional). For example, Japanese Patent Application Laid-Open No. 2004-28263 discloses a characteristic curve indicating constant horsepower control, that is, a characteristic curve in which the discharge amount (delivery amount) of the pump 11 decreases as the discharge pressure of the pump 11 increases. .

  According to this constant horsepower controlled pump, when the load on the actuator increases and the hydraulic pressure in the hydraulic circuit rises, the hydraulic oil discharge rate decreases to keep the pump's output horsepower constant. To do.

JP 2004-28263 A (see FIG. 5B and paragraph [0005])

  However, in the conventional pump controlled by the constant horsepower described above, when the load on the actuator shifts from a high state to a low state suddenly, the pressure of hydraulic oil (corresponding to the pressure of the pump 11) increased by the load of the actuator. )) Suddenly decreases and the amount of hydraulic fluid delivered from the pump increases rapidly. As a result, a sudden change in the flow rate of hydraulic oil occurs in the pipe, and shock pressure is generated in the pipe through which the hydraulic oil flows (water hammer phenomenon). As a result, there has been a problem that the hydraulic circuit piping and components are damaged.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a control device capable of preventing damage to piping and components of a hydraulic circuit due to shock pressure.

  In order to achieve this object, a control device according to claim 1 includes a pump having a constant horsepower control in which a product of a hydraulic pressure and a delivery amount becomes substantially constant, and a control mechanism capable of varying the delivery amount by an external command; A drive device using the liquid pressure of the liquid delivered from the pump as a drive source, a first pipe connected from the liquid delivery side of the pump to one end of the drive device, and a first pipe connected to the first pipe A relief valve for discharging the liquid from the first pipe when the liquid in the tank becomes a predetermined liquid pressure or higher, and a second pipe connected to the liquid suction side of the pump from the other end of the driving device. A hydraulic pressure circuit for controlling whether the hydraulic pressure in the first pipe is equal to or higher than a predetermined hydraulic pressure, and in the first pipe by the hydraulic pressure judgment means When it is determined that the fluid pressure is higher than the prescribed fluid pressure Suppressing shock pressure in the hydraulic circuit caused by rapid increase in delivery rate by the fluid pressure in the rapid reduction and a shock pressure preventing means.

  The control device according to claim 2 is the control device according to claim 1, wherein the hydraulic pressure determination means determines whether the hydraulic pressure is equal to or higher than a predetermined hydraulic pressure based on an open / closed state of the relief valve. .

  The control device according to claim 3 is the control device according to claim 2, wherein the hydraulic circuit includes a relief pipe that constitutes a flow passage through which the liquid discharged from the inside of the first pipe is circulated, and a relief thereof. A pressure sensor for measuring the pressure inside the pipe, and the hydraulic pressure determination means senses the open / closed state of the relief valve based on the measurement result of the pressure sensor.

  The control device according to claim 4 is the control device according to claim 3, wherein the hydraulic circuit includes two pressure sensors, and the two pressure sensors are separated from each other in the flow direction of the relief pipe. The hydraulic pressure determining means senses the open / closed state of the relief valve based on a difference in pressure measured by the two pressure sensors.

  According to a fifth aspect of the present invention, there is provided the control device according to the second aspect, wherein the hydraulic circuit includes a switch device that performs electrical connection and disconnection by performing an on / off operation according to opening and closing of the relief valve. The hydraulic pressure judgment means senses the open / closed state of the relief valve based on the operating state of the switch device.

  A control device according to a sixth aspect is the control device according to any one of the first to fifth aspects, wherein the shock pressure preventing means is configured such that the hydraulic pressure in the first pipe is a predetermined hydraulic pressure by the hydraulic pressure determining means. When it is determined as described above, the maximum delivery amount from the pump is limited by an external command, and the shock pressure of the hydraulic circuit is reduced by suppressing the sudden increase in the pump delivery amount due to the sudden decrease in the hydraulic pressure in the first pipe. Suppress.

  According to the control device of claim 1, the liquid sent from the pump is supplied to the drive device via the first pipe, so that the drive device is driven, and the load on the drive device is low to high. When the hydraulic pressure in the first pipe is increased to a predetermined hydraulic pressure or more in accordance with the transition to the first pipe, the liquid in the first pipe is discharged from the relief valve connected to the first pipe. The hydraulic circuit is configured so that the internal hydraulic pressure is kept below a predetermined hydraulic pressure.

  Here, for example, when the load on the driving device shifts from a high state to a low state, the liquid pressure in the first pipe, which is increased by the load on the driving device, decreases with respect to the liquid delivered by the constant horsepower control pump. Since the flow rate of the liquid delivered from the pump increases due to the decrease in the delivery pressure, the flow rate of the liquid flowing inside the first pipe increases.

  Moreover, by shifting from a high load state to a low load state of the drive device, the flow rate of the liquid flowing into the drive device from the first pipe increases, and as a result, the first pipe passes the drive device through the drive device. 2 The flow rate of the liquid discharged to the pipe increases.

  That is, before the load on the drive device changes from a high state to a low state, the low speed state where the flow rate is constant is the first while the load on the drive device is shifted from a high state to a low state. Since the flow rate of the liquid flowing through the inside of the pipe and the inside of the second pipe is increased, the liquid is in an accelerated state, and after the load of the driving device is shifted to a low state, the increase in the flow rate of the liquid is increased. Since the process is completed, the liquid flow rate becomes constant and a constant speed state is obtained.

  Therefore, the liquid in the constant speed state is changed to the acceleration state, and further, the liquid in the acceleration state is changed to the constant speed state, and the kinetic energy of the liquid is converted into the liquid pressure as the liquid state changes. As a result, shock pressure is generated in the pipe.

  Here, according to the present invention, the hydraulic pressure determining means for determining whether the hydraulic pressure of the first pipe is equal to or higher than the predetermined hydraulic pressure, and the hydraulic pressure determining means determines that the hydraulic pressure is equal to or higher than the predetermined hydraulic pressure. And a shock pressure preventing means for reducing an increase in the flow rate of the liquid supplied from the first pipe to the driving device, so that a shock generated inside the first pipe and inside the second pipe. There is an effect that the pressure can be reduced and damage to the first pipe and the second pipe can be prevented.

  That is, in the present invention, the shock pressure preventing means reduces the increase in the liquid flow rate, so that the mass of the liquid whose state is changed from the steady state to the accelerated state and from the accelerated state to the steady state can be reduced. it can. As a result, there is an effect that the magnitude of shock pressure can be reduced by reducing the kinetic energy of the liquid.

  According to the control device of the second aspect, in addition to the effect produced by the control device of the first aspect, the determination by the hydraulic pressure determination means whether the hydraulic pressure is equal to or higher than a predetermined hydraulic pressure is based on the open / closed state of the relief valve. Therefore, it is possible to determine whether the liquid pressure inside the first pipe is equal to or higher than a predetermined liquid pressure without measuring the liquid pressure inside the first pipe.

  That is, in a hydraulic circuit, it is essential to install a relief valve for circuit protection. According to the present invention, a necessary function can be added using an existing circuit component device (relief valve). There is an effect.

  According to the control device of the third aspect, in addition to the effect of the control device of the second aspect, the hydraulic pressure determination means measures the pressure of the relief pipe through which the liquid discharged from the relief valve is circulated by the pressure sensor. In addition, since the relief valve is opened and closed based on the measured value of the pressure sensor, when the liquid is discharged from the relief valve and the pressure of the relief pipe changes, the change is measured by the pressure sensor. Thus, the opening / closing state of the relief valve can be sensed. Therefore, the open / closed state of the relief valve can be detected by a combination of a general-purpose relief valve (provided only with a valve opening function) and a pressure sensor.

  Therefore, it is not necessary to use a dedicated part, for example, a relief valve in which an output unit that outputs the open / close state of the relief valve is incorporated. As a result, the product cost of the hydraulic circuit can be reduced.

  According to the present invention, since the pressure sensor is configured to measure the pressure inside the relief pipe, it can measure a pressure lower than that inside the first pipe. Therefore, as compared with the case where the pressure inside the first pipe is measured, it is possible to easily ensure the airtightness in attaching the pressure sensor because the pressure to be measured is lower.

  That is, for example, the first pipe is connected between the pump and the drive device, and a high pressure may be applied to the liquid in the first pipe depending on the load applied to the drive device. For this reason, when a hydraulic pressure sensor for measuring the hydraulic pressure is attached to the first pipe, liquid leakage is likely to occur from the connection point between the hydraulic pressure sensor and the first pipe, and the pump is driven when liquid leakage occurs. There is a problem that the driving efficiency for driving the apparatus is deteriorated.

  Therefore, it is necessary to make a connection with high airtightness, and it is necessary to use parts with high processing accuracy and high airtightness and to manage the assembly method. Therefore, there is a problem that the component cost and the manufacturing cost increase, and the product cost increases. In addition, when the usage of frequently changing the setting of the relief pressure (the pressure at which the relief valve is opened), the threshold value (determination pressure value) of the hydraulic pressure judgment means is also changed. This is necessary, and there is a concern about the occurrence of defects due to the difference between the relief pressure and the threshold value. In order to avoid the occurrence of this discrepancy, it is necessary to add a system (means) for associating and setting the relief pressure and the threshold value of the hydraulic pressure judgment means, which increases the product cost.

  On the other hand, according to the present invention, the opening and closing of the relief valve can be detected by measuring the pressure inside the relief pipe. That is, the opening and closing of the relief valve can be detected by measuring the pressure inside the relief pipe, which is a pipe having a lower hydraulic pressure than the first pipe. Therefore, it is possible to solve the problem that the drive efficiency is deteriorated when liquid leakage or liquid leakage occurs from the connection point between the hydraulic pressure sensor and the relief pipe.

  Further, by measuring a relief pipe that is a pipe having a lower hydraulic pressure than the first pipe, a connection with high airtightness can be eliminated. Therefore, the use of parts with high processing accuracy and high airtightness and the management of the assembly method are not required, so that it is possible to prevent the parts cost and the manufacturing cost from increasing, and accordingly, the product cost can be prevented from increasing. There is an effect.

  Furthermore, since the pressure inside the relief pipe is measured to detect the opening and closing of the relief valve, the setting of the relief pressure (the pressure at which the relief valve is opened) needs to be changed frequently. However, it is not necessary to change the setting of the threshold value (determination pressure value) of the hydraulic pressure determination means in accordance with the change. Therefore, it is possible to avoid in advance the occurrence of problems due to the difference between the relief pressure and the threshold value. Further, in order to avoid the occurrence of this discrepancy, it is not necessary to add a system (means) for associating and setting the relief pressure and the threshold value of the hydraulic pressure judgment means, so that the product cost can be prevented from increasing. .

  According to the control device of the fourth aspect, in addition to the effect produced by the control device according to the third aspect, the hydraulic pressure determination means is connected to a position separated in the flow direction of the relief pipe for sensing the open / closed state of the relief valve. Since the configuration is based on the difference in pressure measured by the two pressure sensors, there is an effect that the open / closed state of the relief valve can be accurately detected.

  For example, when the pressure in the relief pipe is measured only at one place, even if the relief valve is not open, the pressure measured by the pressure sensor varies (for example, the pressure inside the pipe is In particular, there is a case where pressure is applied to one end of the relief pipe. Therefore, it is difficult to accurately detect the open / close state of the relief valve.

  On the other hand, in the present invention, since the two pressure sensors respectively measure the pressure inside the relief pipe at positions separated in the flow direction of the relief pipe, the inside of the relief pipe is measured based on the difference between the pressures. Pressure loss occurring in the flowing liquid can be detected. Therefore, since it can be detected that the liquid has flowed into the relief pipe, there is an effect that the open / closed state of the relief valve can be accurately sensed.

  According to the control device of the fifth aspect, in addition to the effect produced by the control device according to the second aspect, the detection of the open / closed state of the relief valve by the hydraulic pressure judging means is turned on / off according to the opening / closing of the relief valve. Therefore, there is an effect that the opening / closing of the relief valve can be accurately detected.

  For example, as a method for detecting the open / closed state of the relief valve, in the method for measuring the presence / absence of the liquid flowing out from the relief valve and the liquid state, the liquid may flow in or out of another pipe. The presence or absence of liquid and its state may change regardless of opening and closing of the relief valve. Therefore, there is a problem that it is difficult to accurately detect opening and closing of the relief valve.

  On the other hand, according to the present invention, since the opening / closing of the relief valve can be directly sensed, the opening / closing state of the relief valve can be reliably sensed compared to the method of measuring the liquid state. As a result, there is an effect that the opening / closing of the relief valve can be accurately detected.

  According to the control device of the sixth aspect, in addition to the effect produced by the control device according to any one of the first to fifth aspects, the shock pressure preventing means reduces the increase in the flow rate of the liquid in the first pipe. Since the maximum pumping amount, which is the maximum flow rate of the liquid sent from the pump to one pipe, is limited by an external command, even if the internal pressure of the first pipe suddenly drops There is an effect that the magnitude of the shock pressure can be reduced by reducing the maximum flow rate of the liquid delivered from the pump and reducing the increase in the flow rate of the liquid flowing inside the first pipe.

  For example, when the amount of increase in the flow rate of the liquid inside the first pipe is reduced by discharging the liquid from the discharge valve that discharges the liquid from the first pipe, the amount of liquid delivered from the pump increases. It is necessary to open the discharge valve before. That is, if the timing of opening the discharge valve is later than the timing of sending the liquid by the pump, there is a problem that the flow rate inside the first pipe increases and the shock pressure generated in the first pipe increases.

  In addition, if the discharge valve is opened in advance, the pump needs to work extra for the amount of liquid discharged from the discharge valve, and the efficiency of the pump deteriorates.

  On the other hand, in the present invention, the maximum flow rate of the pump that sends the liquid to the first pipe is kept low. That is, since the flow rate of the increasing liquid itself is kept low, even if the speed at which the pressure inside the first pipe decreases further becomes faster, the increase amount of the liquid flow rate is reliably suppressed, and the shock pressure is reduced. There is an effect that the size can be reduced.

It is the cross-sectional schematic diagram which showed typically the cross section of the tubing apparatus driven by the hydraulic control apparatus of this invention. It is the schematic circuit diagram which showed schematically the hydraulic circuit of the hydraulic device. It is the control circuit diagram which showed the control circuit of the control apparatus. It is a flowchart which shows a valve control process. It is the schematic circuit diagram which showed schematically the hydraulic circuit of the hydraulic device. It is the schematic circuit diagram which showed schematically the hydraulic circuit of the hydraulic device. It is the characteristic curve figure which showed the characteristic of the pressure and flow volume in a pump.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the embodiment of the present invention, the tubing device 1 will be described as an object to be driven by the hydraulic control device 4 of the present invention. FIG. 1 is a schematic cross-sectional view schematically showing a cross section of a tubing device 1 driven by a hydraulic control device 4 of the present invention. Note that hatching of the main body 2, the chuck device 6, and the thrust device 7 is omitted.

  The tubing device 1 excavates a vertical hole in the ground E. As shown in FIG. 1, the tubing device 1 has a main body 2 fixed to the ground E, and is rotatably held by the main body 2 and has a ground E at the tip portion. The casing 3 having the excavating teeth 3 a to be excavated, the speed reducer 5 that decelerates the rotational force applied from the hydraulic control device 4 and transmits the torque to the casing 3, and the casing 3 is separated from the casing 3 by being separated from the casing 3. A chuck device 6 that switches the transmission state of the rotational force to the shaft, and a thrust device 7 that moves up and down (up and down in FIG. 1) to move the casing 3 in the excavation direction.

  According to this tubing device 1, as shown in FIG. 1, when the chuck device 6 comes into contact with the casing 3, the speed reducer 5 and the casing 3 are connected via the chuck device 6 and rotate from the speed reducer 5 to the casing 3. The force can be transmitted. In this state, the casing 3 is rotated by the rotational force applied from the hydraulic control device 4, and the casing 3 is moved in the excavation direction by the thrust device 7, whereby the ground E is excavated by the excavation teeth 3a.

  Thereafter, when the chuck device 6 is separated from the casing 3 and the connection between the speed reducer 5 and the casing 3 is released, the thrust device 7 can be raised in the direction opposite to the excavation direction (upward in FIG. 1). The thrust device 7 is raised to a position before excavation. Then, the reduction gear 5 and the casing 3 are connected again via the chuck device 6, so that the rotational force is transmitted from the reduction gear 5 to the casing 3. In this state, the hydraulic control device 4 The casing 3 is rotated by the rotational force applied from, and the casing 3 is moved in the excavation direction by the thrust device 7, whereby the ground E is excavated by the excavation teeth 3a. And the excavation of the ground E by the tubing device 1 is continued by repeating these operations.

  Next, the hydraulic device 8 constituting the hydraulic control device 4 will be described with reference to FIG. FIG. 2 is a schematic circuit diagram schematically showing a hydraulic circuit of the hydraulic device 8.

  As shown in FIG. 2, the hydraulic device 8 includes a pump 10, a hydraulic motor 11, a first pipe 12, a direction switching valve 15, a second pipe 14, a relief valve 13, a relief pipe 16, An upstream pressure sensor 17, a downstream pressure sensor 18, an auxiliary machinery pipe 19, an electromagnetic pressure control valve 21, and a motor drain pipe 23 are mainly provided.

  The pump 10 is a device that delivers oil, and is controlled such that when the delivery pressure, which is the pressure for delivering oil, decreases, the amount of oil delivered increases, and when the delivery pressure increases, the amount of oil delivered decreases. Yes. That is, the pump 10 is controlled by constant horsepower control in which the output is kept constant (see range W in FIG. 7). In the present embodiment, oil will be described as an example of the liquid described in claim 1.

  The pump 10 also includes a flow rate control mechanism 10a for varying the maximum delivery amount (corresponding to the “maximum flow rate” described in claim 6), and the flow rate control mechanism 10a includes an electromagnetic pressure described later. A control valve 21 is connected. The pump 10 can vary the maximum delivery amount when the flow rate control mechanism 10 a receives the command pressure sent by the electromagnetic pressure control valve 21. In the present embodiment, when the command pressure of the electromagnetic pressure control valve 21 is Pi1, the maximum delivery amount of the pump 10 is set to the flow rate QM, and when the command pressure of the electromagnetic pressure control valve 21 is Pi2, the pump 10 The maximum delivery amount is set to the flow rate Q2, and the flow rate is Q1 at the circuit maximum pressure PM. Here, Pi1 <Pi2 and Q1 <Q2 <QM. However, the flow rate Q2 may be smaller than the flow rate Q1.

  The hydraulic motor 11 is a device that applies a rotational force to the casing 3 (see FIG. 1) by being rotationally driven using the oil pressure of the oil delivered from the pump 10 as a drive source.

  As shown in FIG. 2, the first pipe 12 is a pipe that constitutes an oil passage for supplying the oil sent from the pump 10 to the hydraulic motor 11. One end of the first pipe 12 is connected to a direction switching valve 15 described later and the other. The end is connected to the oil delivery outlet of the pump 10.

  As shown in FIG. 2, the direction switching valve 15 is an electromagnetic valve that switches the supply of oil to the hydraulic motor 11. The direction switching valve 15 is a first pipe 12 to the pipe h <b> 1 and the pipe h <b> 2 connected to the hydraulic motor 11 and a first pipe that will be described later. By switching the connection of the two pipes 14, the oil supply direction to the pipe h1 or the pipe h2 is switched or the supply is stopped.

  The second pipe 14 is a pipe that constitutes an oil passage that discharges the oil supplied to the hydraulic motor 11, and has one end connected to the direction switching valve 15 and the other end connected to the oil recovery port of the pump 10. Yes.

  When the direction switching valve 15 is switched to the first state or the second state, the first pipe 12 is connected to the pipe h1 or the pipe h2 (the second pipe 14 is the pipe h2 or the pipe h1). The hydraulic motor 11 is driven forward or reversely by the hydraulic pressure supplied through the pipe 12. When the direction switching valve 15 is switched to the third state, the hydraulic pressure from the pump 10 is not supplied to the hydraulic motor 11 but flows directly from the first pipe 12 to the second pipe 14.

  As shown in FIG. 2, the relief valve 13 is a valve that discharges oil from the inside of the first pipe 12 to a relief pipe 16 to be described later when the oil pressure inside the first pipe 12 exceeds a predetermined oil pressure. It is interposed between the first pipe 12 and the relief pipe 16.

  The relief valve 13 is opened when the hydraulic pressure of the first pipe 12 reaches PM (see FIG. 7), and allows the first pipe 12 and the relief pipe 16 to communicate with each other. As a result, the oil in the first pipe 12 is discharged to the relief pipe 16. When the hydraulic pressure of the first pipe 12 does not reach the hydraulic pressure PM, the first pipe 12 is closed and the first pipe 12 and the relief pipe 16 are disconnected.

  The relief pipe 16 is a pipe constituting an oil passage through which oil discharged through the relief valve 13 is circulated. One end of the relief pipe 16 is connected to the relief valve 13 and the other end is connected to the second pipe 14. .

  As shown in FIG. 2, the upstream pressure sensor 17 and the downstream pressure sensor 18 are pressure sensors that measure the pressure inside the relief pipe 16, and are both connected to the relief pipe 16. That is, when oil flows through the relief pipe 16, a pressure difference is generated between the upstream portion and the downstream portion of the relief pipe 16 due to the viscous resistance. Therefore, the pressure gradient generated in the relief pipe 16 can be detected by comparing the measured values of the upstream pressure sensor 17 and the downstream pressure sensor 18, and it is determined whether oil is flowing in the relief pipe 16. Can be detected.

  Specifically, the upstream pressure sensor 17 is connected to the relief pipe 16 at a position on the upstream side of the downstream pressure sensor 18 (the side close to the relief valve 13 on the oil circulation path through the inside of the relief pipe 16). Therefore, when the measured value of the upstream pressure sensor 17 is larger than the measured value of the downstream pressure sensor 18, the oil flowing inside the relief pipe 16 flows from the upstream pressure sensor 17 to the downstream pressure sensor 18. I can judge.

  The auxiliary equipment pipe 19 is a pipe to which auxiliary equipment such as an oil cooler 20 is connected. One end of the auxiliary pipe 19 is connected to the second pipe 14 and the other end is connected to a tank h3 that stores oil. Further, since the auxiliary equipment pipe 19 is connected to the downstream side of the hydraulic motor 11, almost all of the oil pressure (hereinafter referred to as “hydraulic pressure”) supplied from the pump 10 is driven by the hydraulic motor 11. Therefore, since the hydraulic pressure generated in the auxiliary pipe 19 is smaller than that of the first pipe 12, the auxiliary pipe 19 is a pipe having lower strength than the first pipe 12. Configured.

  The electromagnetic pressure control valve 21 is an electromagnetic proportional valve that operates based on a command from the CPU 30 described later. As described above, the command pressure is sent to the flow rate control mechanism 10a, and the maximum delivery amount of the pump 10 is set. To change.

  Next, the configuration of the control device 9 that controls the hydraulic device 8 will be described with reference to FIG. FIG. 3 is a control circuit diagram showing a control circuit of the control device 9.

  The control device 9 includes a CPU 30 that is an arithmetic device, a ROM 31 that records various control programs executed by the CPU 30 and fixed data, and a RAM 32 that is a memory for temporarily storing various data. . The CPU 30, ROM 31 and RAM 32 are connected to each other via a bus line 33, and the bus line 33 is also connected to an input / output port 34.

  The valve control program 35 stores the program of the flowchart shown in FIG. 4, and the determination pressure value 36 stores a determination pressure value used when determining whether the relief valve 13 is opened or closed. . Further, the upstream measured pressure value 37 and the downstream measured pressure value 38 store the output values of the upstream pressure sensor 17 and the downstream pressure sensor 18 described above, respectively. Further, as shown in FIG. 3, the upstream pressure sensor 17, the downstream pressure sensor 18, the electromagnetic pressure control valve 21, and other devices 23 are connected to the input / output port 34.

  Next, the valve control process executed by the control device 9 will be described with reference to FIG. FIG. 4 is a flowchart showing the valve control process. This process is a process repeatedly executed by the CPU 30 while the power of the control device 9 is turned on, and the oil in the pipe is drastically changed when the load of the hydraulic motor 11 is shifted from a high state to a low state. This is a process for reducing the magnitude of the shock pressure and preventing the pipe from being damaged even when the shock pressure is generated due to the flow rate change.

  In addition, in description of the valve control process of FIG. 4, FIGS. 5-7 is referred suitably. 5 and 6 are schematic circuit diagrams schematically showing the hydraulic circuit of the hydraulic control device 4. FIG. 5 shows the hydraulic motor 11 driven by the hydraulic pressure of the pump 10 with the relief valve 13 closed. FIG. 6 shows a state in which the operation of the hydraulic motor 11 is stopped (oil does not pass through the hydraulic motor 11) when the relief valve 13 is open. FIG. 7 is a characteristic curve diagram showing characteristics of pressure and flow rate in the pump 10. In FIGS. 5 and 6, piping through which oil is circulated is indicated by a thick line, and the direction in which oil circulates is indicated by an arrow.

  Regarding the valve control processing, the CPU 30 first sets the command pressure to Pi1 by the electromagnetic pressure control valve 21 in order to set the pump 10 to the initial state (S1). As a result, as described above, the command pressure Pi1 is applied to the flow rate control mechanism 10a, whereby the maximum delivery amount of the pump 10 is set to the flow rate QM (see FIG. 7).

  Here, the flow of oil in the hydraulic device 8 will be described with reference to FIGS. 5 and 7. As described above, the pump 10 is set in the initial state, and the pump 10 is connected in a state where the first pipe 12 and the pipe h1 are connected and the pipe h2 and the second pipe 14 are connected by the direction switching valve 15. Is driven, the oil sent from the pump 10 flows into the hydraulic motor 11 through the first pipe 12 and the pipe h1, and the hydraulic motor 11 is driven. The motor drain pipe 23 connects the drain port of the motor 11 and the second pipe 14 and collects the drain oil of the motor 11.

  When the hydraulic motor 11 is driven, the casing 3 is rotated via the speed reducer 5, and the ground E is excavated by this rotation. As a result, the load applied to the hydraulic motor 11 increases, and as the load increases, the delivery pressure of the pump 10 increases. As shown in FIG. 7, when the delivery pressure is in the range of 0 to P1, the pump 10 output horsepower increases.

  When the load applied to the hydraulic motor 11 is further increased and the delivery pressure becomes higher than P1, the output of the pump 10 is controlled by a constant horsepower as shown in FIG. In this constant horsepower control (area indicated by the range W), as described above, the product of the delivery pressure and the delivery amount is substantially constant, that is, when the delivery pressure of the pump 10 is increased, the delivery amount of the pump 10 is decreased. (When the delivery pressure of the pump 10 is decreased, the delivery amount of the pump 10 is increased). The oil discharged from the hydraulic motor 11 is discharged from the pipe h2 to the second pipe 14 through the direction switching valve 15, flows through the second pipe 14, and flows into the oil recovery port of the pump 10.

  Returning to FIG. In the process of S1, after the command pressure is set to Pi1 by the electromagnetic pressure control valve 21 and the maximum delivery amount of the pump 10 is set to QM, then a predetermined time Δt (for example, 10 msec in this embodiment) from the start of the previous time measurement. ) Is determined (S2). Note that the CPU 30 (see FIG. 3) includes a timer circuit, and the pressure in the relief pipe 16 is confirmed periodically (every predetermined time Δt) by measuring time with this timer circuit.

  That is, if it is determined in the process of S2 that the predetermined time Δt has elapsed (S2: Yes), it means that the predetermined time Δt has elapsed since the previous confirmation process and the timing of the next confirmation process has arrived. In order to execute such confirmation processing, first, the CPU 30 reads the output of the upstream pressure sensor 17 and stores the read value in the upstream measurement pressure value 37 of the RAM 32 (S3), and the output of the downstream pressure sensor 18 And the read value is stored in the downstream measured pressure value 38 of the RAM 32 (S4).

  After the output values of the upstream pressure sensor 17 and the downstream pressure sensor 18 are read in the processing of S3 and S4, the difference between the output values of these two pressure sensors (the upstream pressure sensor 17 and the downstream pressure sensor 18) is the judgment pressure value. It is determined whether it is equal to or greater than the determination pressure value stored in 36 (S5).

  Here, as described above, by comparing the values of the upstream pressure sensor 17 and the downstream pressure sensor 18 and detecting the pressure gradient inside the relief pipe 16, an oil flow is generated inside the relief pipe 16. It can be determined whether or not. That is, the open / closed state of the relief valve 13 can be sensed.

  Therefore, in the process of S5, when the difference between the output values of the two pressure sensors (the upstream pressure sensor 17 and the downstream pressure sensor 18) is not determined to be greater than or equal to the determination pressure value, that is, when it is determined that the difference is smaller than the determination pressure value. (S5: No), it means that oil has not flowed into the relief pipe 16 or that an oil leak from the relief valve 13 has been detected, and it can be determined that the relief valve 13 is closed. The command pressure of the electromagnetic pressure control valve 21 is confirmed (S7). When the command pressure of the electromagnetic pressure control valve 21 is Pi1 (S7: Pi1), the command pressure is not changed by the electromagnetic pressure control valve 21. On the other hand, if the command pressure of the electromagnetic pressure control valve 21 is Pi2 (S7: Pi2) while the process proceeds to other processing (S9), the command pressure by the electromagnetic pressure control valve 21 is changed from Pi2 to Pi1. Change people in (S8), the process proceeds to other processing (S9).

  Thereby, the command pressure to the flow control mechanism 10a is held at Pi1, and the maximum delivery amount of the pump 10 is set to the QM state (see FIG. 7). In addition, after performing the process of S9, it transfers to S2.

  On the other hand, in the process of S2, if it is not determined that the predetermined time Δt has elapsed since the start of the previous time measurement (S2: No), the predetermined time Δt has not yet elapsed since the previous confirmation process, and the next confirmation process Therefore, the process proceeds to S9 in order to execute other processes using the time until the next timing arrives.

  On the other hand, in the process of S5, when it is determined that the difference between the output values of the two pressure sensors (the upstream pressure sensor 17 and the downstream pressure sensor 18) is equal to or greater than the determination pressure value (S5: Yes), the relief pipe 16 is provided inside. This means that the oil is flowing, and it can be determined that the relief valve 13 is open. Therefore, the command pressure is set to Pi2 by the electromagnetic pressure control valve 21 (S6), and the process proceeds to other processing (S9).

  Thereby, the command pressure Pi2 is applied to the flow rate control mechanism 10a, and the maximum delivery amount of the pump 10 is set to the state of Q2 (see FIG. 7). As a result, in a state where the load of the hydraulic motor 11 has shifted from a high state to a low state, the oil in the hydraulic device 8 is prevented from changing abruptly and the magnitude of the shock pressure is reduced. Damage to the first pipe 12 and the like can be prevented.

  Here, the flow of oil in the hydraulic device 8 will be described with reference to FIGS. 6 and 7. As described above, when the hydraulic motor 11 is driven by the oil supplied from the pump 10 and the ground E is excavated by the casing 3 (see FIG. 1), the excavating teeth 3a of the casing 3 bite a hard stone or the like. When the rotation of the hydraulic motor 11 is stopped, the oil does not flow inside the hydraulic motor 11 as shown in FIG.

  That is, when the pressure in the first pipe 12 increases and the pressure reaches the hydraulic pressure PM of the relief valve 13, the relief valve 13 is opened, and the oil in the first pipe 12 is relieved through the relief valve 13. It is discharged to the pipe 16.

  In this case, as described above, since the hydraulic pressure in the relief pipe 16 is detected by the upstream pressure sensor 17 and the downstream pressure sensor 18, the state (open state or closed state) of the relief valve 13 is determined from the detection result. (See S5).

  The fact that the hydraulic pressure of the first pipe 12 is PM means that the delivery pressure of the pump 10 is also PM. In this case, since the pump 10 is controlled by a constant horsepower, the amount of oil delivered from the pump 10 is Q1 (see FIG. 7). Therefore, in a state where oil does not flow into the hydraulic motor 11, the flow rate of the oil flowing from the relief valve 13 to the relief pipe 16 becomes the amount of the flow rate Q1.

  As described above, in a state where the rotation of the hydraulic motor 11 is stopped, for example, when the rotation of the hydraulic motor 11 is restored by crushing hard stones or the like, the load on the hydraulic motor 11 is suddenly increased. As a result, the delivery pressure of the pump 10 becomes smaller than the hydraulic pressure PM. As a result, the delivery amount of the pump 10 is increased (see FIG. 7).

  Further, when the delivery pressure of the pump 10 becomes smaller than the hydraulic pressure PM, the relief valve 13 is closed and oil discharge from the first pipe 12 to the relief pipe 16 is stopped, so that most of the oil delivered by the pump 10 is the first. The first pipe 12 flows into the second pipe 14 via the hydraulic motor 11.

  Since the pump 10 increases the flow rate of the oil sent to the first pipe 12 as the hydraulic pressure decreases (see FIG. 7), the first flow rate is increased while the flow rate sent from the pump 10 is increasing. The oil inside the pipe 12 is accelerating, and then becomes constant when the flow rate is fixed. That is, in the oil, an acceleration state change from constant speed to acceleration and further to constant speed occurs, and an impact is applied to the inside of the first pipe 12 due to a change in inertia force accompanying the change in the acceleration state. As a result, shock pressure is generated.

  Further, since the hydraulic motor 11 is rotated by discharging the inflowing oil, the same amount of oil as the first pipe 12 flows through the second pipe 14. Thus, shock pressure is also generated in the second pipe 14 under conditions where shock pressure is generated in the first pipe 12.

  As described above, when the hydraulic motor 11 is loaded, the hydraulic pressure of the second pipe 14 is lower than the hydraulic pressure of the first pipe 12. Therefore, a pipe having a lower strength than that of the first pipe 12 can be used for the second pipe 14, thereby reducing the component cost. However, the second pipe 14 has a problem that it is more easily damaged by shock pressure than the first pipe 12.

  The second pipe 14 is connected to an auxiliary machine pipe 19 and a motor drain pipe 23 to which a relief pipe 16, an oil cooler 20 and the like are attached. The relief pipe 16, the oil cooler 20, and the auxiliary machines are connected to the second pipe 14. Since the pipe 19 and the motor drain pipe 23 are set to be lower in strength than the first pipe 12 like the second pipe 14, when the shock pressure generated in the second pipe 14 is propagated, the relief pipe 19 16, there is a problem that the oil cooler 20, the auxiliary equipment piping 19, the motor drain piping 23, or the motor 11 itself is damaged.

  On the other hand, according to the first embodiment, as described in the valve control process (see FIG. 4), when the relief valve 13 is determined to be open by the process of S5, the process of S6 is performed. Thus, the maximum delivery amount of the pump 10 is changed from the flow rate QM to the flow rate Q2, so that the increase amount of the flow rate of the oil supplied from the first pipe 12 to the hydraulic motor 11 can be reduced. Therefore, compared with the case where the maximum delivery amount of the pump 10 is set to the flow rate QM, the magnitude of the shock pressure generated in the first pipe 12 and the second pipe 14 can be reduced.

  As a result, damage to the first pipe 12 and the second pipe 14 can be prevented, and shock pressure is transmitted to the relief pipe 16, the oil cooler 20, and the auxiliary equipment pipe 19 connected to the second pipe 14. It can be prevented from being damaged.

  That is, in the first embodiment, since the amount of increase in the oil flow rate is reduced, the mass of the oil whose state is changed from the constant speed state to the acceleration state and from the acceleration state to the constant speed state can be reduced. As a result, the magnitude of shock pressure can be reduced by reducing the kinetic energy of the oil.

  Here, a discharge valve for discharging oil from the first pipe 12 is provided between the pump 10 and the first pipe 12, and the oil flow rate in the first pipe 12 is increased by discharging oil from the discharge valve. When reducing the amount, it is necessary to open the discharge valve before the amount of oil delivered from the pump 10 increases. That is, if the timing for opening the discharge valve is later than the timing for sending oil by the pump 10, there is a problem that the flow rate inside the first pipe 12 increases and the shock pressure generated in the first pipe 12 increases.

  In addition, if the discharge valve is opened in advance, the pump 10 needs to perform extra work as oil is discharged from the discharge valve, and the efficiency of the hydraulic device 8 deteriorates.

  On the other hand, in 1st Embodiment, the maximum sending amount of the pump 10 which sends oil to the 1st piping 12 is restrained low. That is, since the increasing oil flow rate itself is kept low, even if the speed at which the internal pressure of the first pipe 12 decreases further becomes faster, the increase amount of the oil flow rate can be reliably suppressed to reduce the shock pressure. Can be reduced in size.

  Moreover, in 1st Embodiment, when the pressure of the 1st piping 12 falls, the maximum delivery amount of the pump 10 is restrained low. That is, since the work of the pump 10 is kept low in a state where the hydraulic motor 11 does not require a driving force (a state where the pressure of the first pipe 12 is reduced), deterioration of the efficiency of the hydraulic device 8 can be prevented. .

  Further, as described above, according to the first embodiment, the pressure of the relief pipe 16 through which the oil discharged from the relief valve 13 is circulated is measured by the upstream pressure sensor 17 and the downstream pressure sensor 18, and the process of S5 is performed. Therefore, the open / close state of the relief valve 13 can be determined without measuring the oil pressure inside the first pipe 12 because the open / close state of the relief valve 13 is detected based on the measured values of the pressure sensors. it can.

  For example, the first pipe 12 is connected between the pump 10 and the hydraulic motor 11, and a high pressure is applied to the oil in the first pipe 12 depending on the magnitude of the load applied to the hydraulic motor 11. There is also. For this reason, when a hydraulic pressure sensor for measuring the hydraulic pressure is attached to the first pipe 12, oil leakage is likely to occur from the connecting portion between the hydraulic pressure sensor and the first pipe 12, and when the oil leakage occurs, the pump 10 There is a problem that the driving efficiency for driving the motor 11 is deteriorated.

  Therefore, it is necessary to make a connection with high airtightness, and it is necessary to use parts with high processing accuracy and high airtightness and to manage the assembly method. Therefore, there is a problem that the component cost and the manufacturing cost increase, and the product cost increases.

  On the other hand, according to the first embodiment, it is determined whether the oil pressure inside the first pipe 12 is equal to or higher than a predetermined pressure value without measuring the oil pressure inside the first pipe 12. Therefore, it is unnecessary to connect a hydraulic pressure sensor to the first pipe 12, and reliability can be improved. Therefore, it is possible to solve the problem that the drive efficiency deteriorates when oil leaks or oil leaks from the connection point between the hydraulic sensor and the first pipe 12.

  Moreover, the connection which maintained the high airtightness at the time of connecting a hydraulic pressure sensor to the 1st piping 12 becomes unnecessary. Therefore, it is not necessary to use parts with high processing accuracy and high airtightness, management of the assembly method, and the like, and it is possible to prevent the parts cost and the manufacturing cost from increasing, thereby preventing the product cost from increasing.

  Further, as described above, according to the first embodiment, the pressure of the relief pipe 16 through which the oil discharged from the relief valve 13 is circulated is measured by the upstream pressure sensor 17 and the downstream pressure sensor 18, and the process of S5 is performed. Therefore, the open / close state of the relief valve 13 is sensed based on the measured values of the pressure sensors. Therefore, the relief valve 13 is combined with a general-purpose relief valve 13 (provided only with a valve opening function) and the pressure sensor. Open / closed state can be detected.

  Therefore, it is not necessary to use a dedicated part, for example, the relief valve 13 in which an output unit that outputs the open / close state of the relief valve 13 is incorporated. As a result, the product cost of the hydraulic device 8 can be reduced.

  Further, as described above, according to the first embodiment, the upstream pressure sensor 17 or the downstream pressure sensor 18 is configured to measure the pressure inside the relief pipe 16, and thus is lower than the inside of the first pipe 12. The pressure can be measured. Therefore, as compared with the case where the pressure inside the first pipe 12 is measured, it is possible to easily ensure airtightness in attaching the upstream pressure sensor 17 or the downstream pressure sensor 18 because the pressure to be measured is lower.

  That is, for example, the first pipe 12 is connected between the pump 10 and the hydraulic motor 11, and high pressure is applied to the oil inside the first pipe 12 depending on the magnitude of the load applied to the hydraulic motor 11. There is also a case.

  For this reason, when a hydraulic pressure sensor for measuring the hydraulic pressure is attached to the first pipe 12, oil leakage is likely to occur from the connecting portion between the hydraulic pressure sensor and the first pipe 12, and when the oil leakage occurs, the pump 10 There is a problem that the driving efficiency for driving the motor 11 is deteriorated.

  Therefore, it is necessary to make a connection with high airtightness, and it is necessary to use parts with high processing accuracy and high airtightness and to manage the assembly method. Therefore, there is a problem that the component cost and the manufacturing cost increase, and the product cost increases.

  On the other hand, according to the first embodiment, the opening and closing of the relief valve 13 can be detected by measuring the pressure inside the relief pipe 16. That is, the opening and closing of the relief valve 13 can be detected by measuring the pressure inside the relief pipe 16, which is a pipe whose hydraulic pressure is lower than that of the first pipe 12. Therefore, it is possible to solve the problem that the drive efficiency deteriorates when oil leaks or oil leaks from the connection point between the hydraulic pressure sensor and the relief pipe 16.

  Further, by measuring the relief pipe 16, which is a pipe having a lower hydraulic pressure than the first pipe 12, a connection with high airtightness can be eliminated. Therefore, the use of parts with high processing accuracy and high airtightness and the management of the assembly method are not required, so that it is possible to prevent the parts cost and the manufacturing cost from increasing, and accordingly, the product cost can be prevented from increasing. .

  Further, according to the control device 9 in the first embodiment, the process of S5 includes two pressure sensors (upstream) connected to a position separated in the flow direction of the relief pipe 16 for sensing the open / closed state of the relief valve 13. Since the configuration is based on the difference in pressure measured by the pressure sensor 17 and the downstream pressure sensor 18), it is possible to accurately detect the open / closed state of the relief valve 13.

  For example, when the pressure of the relief pipe 16 is measured only at one place, even when the relief valve 13 is not open, the pressure measured by the pressure sensor varies (for example, the pressure inside the pipe). Is a case where pressure is applied to one end of the relief pipe 16). Therefore, it is difficult to accurately detect the open / closed state of the relief valve 13.

  On the other hand, in the first embodiment, the upstream pressure sensor 17 and the downstream pressure sensor 18 are connected to a position separated in the flow direction of the relief pipe 16, and the relief pipe 16 at a position separated in the flow direction of the relief pipe 16. Therefore, the pressure loss generated in the oil flowing through the relief pipe 16 can be detected based on the difference between the pressures. Therefore, since it can be detected that oil has flowed into the relief pipe 16, the open / closed state of the relief valve 13 can be accurately sensed.

  Next, a second embodiment will be described. In the first embodiment, the open / close state of the relief valve 13 is determined by sensing the oil pressure of the oil flowing through the relief pipe 16 with a pressure sensor. Instead, in the second embodiment, the detection is performed by electrical connection and disconnection of the switch device (corresponding to “ON / OFF operation” according to claim 5).

  That is, in the second embodiment, a connecting portion that operates mechanically in response to opening and closing of the relief valve 13 and a switch device that is connected to the connecting portion and electrically connected or disconnected by the operation of the connecting portion. And detecting the open / closed state of the relief valve 13 in the process of S5 by detecting the electrical connection and disconnection of the switch device (corresponding to the “on / off operation” according to claim 5).

  The hydraulic circuit in the second embodiment is the same as the hydraulic circuit 8 shown in FIG. 2 described above instead of the upstream pressure sensor 17 and the downstream pressure sensor 18 or in addition to the upstream pressure sensor 17 and the downstream pressure sensor 18. The connecting portion is connected to the relief valve 13, and the switch device is connected to the connecting portion. The other configuration except for the connecting portion and the switch device is the same as the configuration shown in FIG. The switch device corresponds to a part of the other device 23 in the control circuit diagram shown in FIG. Therefore, the CPU 30 of the control device 9 detects the electrical connection and disconnection of the switch device (other device 23) via the input / output port 34, and based on the detection result, the open / close state of the relief valve 13 is determined. Sense. Note that the CPU 30 taking in the electrical change output from the switch device as an electrical signal corresponds to the hydraulic pressure determination means of claim 1.

  As described above, in the second embodiment, since the opening / closing of the relief valve 13 is detected using the switch device, the opening / closing of the relief valve 13 can be accurately detected. For example, as a method for detecting the open / closed state of the relief valve 13, in the method of measuring the presence or absence of oil flowing out from the relief valve 13 or the state of the oil, the oil flows in or flows out from another pipe. As a result, the presence or absence of oil or its state may change regardless of whether the relief valve 13 is opened or closed. Therefore, there is a problem that it is difficult to accurately detect the opening / closing of the relief valve 13.

  On the other hand, according to the second embodiment, the switch device performs electrical connection and disconnection by the operation of the connection unit, and the CPU 30 performs an electrical signal in a process that replaces the electrical change with the process of S5. Capture as. Therefore, the opening / closing of the relief valve 13 can be directly detected. Therefore, the open / closed state of the relief valve 13 can be reliably detected as compared with the method of measuring the oil state. As a result, opening / closing of the relief valve 13 can be detected with high accuracy.

  The present invention has been described above based on the embodiments. However, the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention. It can be easily guessed.

  The numerical values (for example, the quantity of each component) given in the above embodiment are examples, and other numerical values can naturally be adopted.

  For example, in the above-described embodiment, the case where the hydraulic device 8 includes two pressure sensors (the upstream pressure sensor 17 and the downstream pressure sensor 18) has been described. It is good also as a structure provided with an individual pressure sensor.

  In this case, since the hydraulic pressure of the relief pipe 16 can be measured even with one pressure sensor, the open / closed state of the relief valve 13 can be detected. Therefore, the cost can be reduced by reducing the number of parts constituting the hydraulic device 8.

  For example, in the second embodiment, a case is described in which the switch device performs electrical connection and disconnection by the operation of the connection unit, and the CPU 30 captures the electrical change as an electrical signal in the process in place of the process of S5. However, the present invention is not necessarily limited thereto, and includes a light emitting unit that emits a light beam, and a light receiving unit that outputs an electric signal by receiving the light beam emitted by the light emitting unit. It is good also as a structure which switches light-receiving to light-receiving part, and interruption | blocking. Note that the CPU 30 taking in the electrical signal from the light receiving unit corresponds to the hydraulic pressure determination means of claim 1.

  In this case, the operation of the connecting part connected to the relief valve 13 switches between receiving and blocking of the light beam to the light receiving part, so that the CPU 30 takes in the electric signal from the light receiving part and judges the change of the electric signal. Thus, the open / closed state of the relief valve 13 can be detected without contact.

  Therefore, the occurrence of contact failure of the switch device due to oil or dust can be suppressed. As a result, the open / closed state of the relief valve 13 can be reliably detected even in an environment where there is a lot of oil or dust.

  The above-described light beam may be, for example, a laser beam and an infrared ray. In particular, when a laser beam is used, the straightness of the beam is higher than that when an infrared beam is used, and thus the width of the beam can be narrowed. Therefore, it is possible to change the light receiving state of the light receiving unit (whether or not the light is received) even with a slight movement of the connecting unit. As a result, the detection accuracy of the open / closed state of the relief valve 13 can be further increased.

  Further, when infrared rays are used, since the wavelength is longer than when laser rays are used, the manufacturing cost of the light emitting part can be suppressed. As a result, the cost of the control device 9 can be reduced.

  In each of the above embodiments, the case where the upstream pressure sensor 17 and the downstream pressure sensor 18 are connected to the relief pipe 16 and the oil pressure of the oil flowing through the relief pipe 16 is measured by the upstream pressure sensor 17 and the downstream pressure sensor 18 is described. However, in addition thereto, a pressure sensor may be connected to the first pipe 12 to measure the pressure of the first pipe 12.

  In this case, even if any one of the pressure sensors is broken (disconnection or output of an abnormal value), the relief valve is compared by comparing the pressure values measured by the remaining two instead of the process of S5. 13 open / closed states can be sensed.

  In the first embodiment, the upstream pressure sensor 17 and the downstream pressure sensor 18 are connected to the relief pipe 16, and the oil pressure of the oil flowing inside the relief pipe 16 is measured by the upstream pressure sensor 17 and the downstream pressure sensor 18. In the second embodiment, the switch device performs electrical connection and disconnection by the operation of the connecting portion, and the CPU 30 captures the electrical change as an electrical signal in a process in place of the process of S5. Although the case where it is set as the structure which senses 13 opening-and-closing states was demonstrated, you may use combining them.

  In this embodiment, the process of S5 in FIG. 4 corresponds to the hydraulic pressure determination means in claim 1, and the process of S6 in FIG. 4 corresponds to the shock pressure prevention means in claim 1.

9 Control device 8 Hydraulic device (hydraulic circuit)
10 Pump 10a Flow control mechanism (part of pump, control mechanism)
11 Hydraulic motor (drive device)
12 1st piping 13 Relief valve 14 2nd piping 16 Relief piping 17 Upstream pressure sensor (pressure sensor)
18 Downstream pressure sensor (pressure sensor)
19 Auxiliary piping (part of second piping)
P1, P2, PM Hydraulic pressure (hydraulic pressure)

Claims (6)

A pump having a horsepower constant control in which the product of the fluid pressure and the delivery amount becomes substantially constant and a control mechanism capable of varying the delivery amount by an external command, and a drive device using the fluid pressure of the fluid delivered from the pump as a drive source, The first pipe connected from the liquid delivery side of the pump to one end of the driving device, and the liquid in the first pipe connected to the first pipe when the liquid in the first pipe becomes equal to or higher than a predetermined hydraulic pressure. In a control device for controlling a hydraulic circuit constituted by a relief valve for discharging from the pipe and a second pipe connected to the liquid suction side of the pump from the other end of the driving device,
Hydraulic pressure determining means for determining whether the hydraulic pressure in the first pipe is equal to or higher than a predetermined hydraulic pressure;
A shock that suppresses the shock pressure of the hydraulic circuit generated by a sudden increase in the delivery amount due to a sudden decrease in the hydraulic pressure when the hydraulic pressure judgment means judges that the hydraulic pressure in the first pipe is equal to or higher than a predetermined hydraulic pressure. And a pressure prevention means.   The control device according to claim 1, wherein the hydraulic pressure determination unit determines whether the hydraulic pressure is equal to or higher than a predetermined hydraulic pressure based on an open / closed state of the relief valve. The hydraulic circuit includes a relief pipe that constitutes a flow passage for flowing the liquid discharged from the inside of the first pipe;
A pressure sensor for measuring the pressure inside the relief pipe,
3. The control apparatus according to claim 2, wherein the hydraulic pressure determination unit detects the open / closed state of the relief valve based on a measurement result of the pressure sensor. The hydraulic circuit includes two of the pressure sensors, and the two pressure sensors are connected to positions separated in the flow direction of the relief pipe,
4. The control apparatus according to claim 3, wherein the hydraulic pressure determination unit performs detection of an open / closed state of the relief valve based on a difference in pressure measured by the two pressure sensors. The hydraulic circuit includes a switch device that performs electrical connection and disconnection by turning on and off according to opening and closing of the relief valve,
The control device according to claim 2, wherein the hydraulic pressure determination unit senses an open / closed state of the relief valve based on an operating state of the switch device.   The shock pressure preventing means limits the maximum delivery amount from the pump by an external command when the hydraulic pressure determining means determines that the hydraulic pressure in the first pipe is equal to or higher than a predetermined hydraulic pressure, The control device according to claim 1, wherein a shock pressure of the hydraulic circuit is suppressed by suppressing a sudden increase in a pump delivery amount due to a sudden decrease in the hydraulic pressure in one pipe.

Images