Pressure oil supply and discharge system

Abstract

To detect an abnormal state of a pressurized oil supply / discharge system that has not been detected conventionally.SOLUTION: A pump (1) driven by supplying compressed air supplies pressurized oil to a cylinder (10) via a flow passage. A three-way valve (2) provided in a middle part of the flow passage enables switching between a state where the pressurized oil is supplied from the pump (1) to the cylinder (10) and a state where the pressurized oil is discharged from the cylinder (10) to the outside. When pressure of the pressurized oil in the flow passage exceeds predetermined pressure, a pressure compensation valve (3) discharges the pressurized oil to the outside so that the pressure of the pressurized oil in the flow passage becomes below the predetermined pressure. A flow rate of the compressed air supplied to the pump (1) is detected by an air flow rate detection sensor (5). The pressure of the pressurized oil in the flow passage is detected by an oil pressure detection sensor (6).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to a system for supplying and discharging pressurized oil to and from an object to be supplied and discharged with pressurized oil.

Background Art

[0002] Conventionally, there is a pressurized oil supply and discharge system described in Patent Document 1 (Japanese Patent Laid-Open No. 3-181682). The prior art is configured as follows. The pressurized oil supply and discharge system has a pump, a three-way valve and a pressure safeguard valve provided in the middle of a flow path connecting the pump and a cylinder as an object of pressure supply and discharge. The pump is configured such that a piston is driven by compressed air supplied from a compressed air source, and a plunger connected to the piston sends oil in an oil tank to the cylinder. The above three-way valve is configured to switch between a state of supplying pressurized oil from the pump to the cylinder and a state of discharging the pressurized oil in the cylinder to the outside. The above pressure safeguard valve discharges the pressurized oil to the outside when the pressurized oil supplied from the pump exceeds a predetermined pressure, so that the pressurized oil is below the predetermined pressure. Whether the oil pressure in the flow path is higher than a predetermined pressure is detected by a pressure detection switch provided in the flow path of the pressurized oil connecting the pump and the cylinder.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The above prior art has the following problems. Even when it is determined that the system is in a normal state because the pressure detecting switch detects that the pressure oil in the flow path is at an appropriate pressure, there may be an abnormal state in which the pressure oil supply and discharge system operates excessively, or an abnormal state in which there is a leak in the piping. Such abnormal states cannot be detected only by the pressure detecting switch. An object of the present invention is to be able to detect an abnormal state of a pressure oil supply and discharge system that could not be detected conventionally.

Means for Solving the Problems

[0005] To achieve the above object, the present invention configures a pressure oil supply and discharge system as follows, for example, as shown in FIGS. 1 to 3 or FIG. 4. The pump 1 is driven by supplying compressed air, and the pump 1 discharges pressure oil to the pressure oil supply and discharge object 10. A three-way valve 2 is provided in the middle of the flow path for supplying and discharging pressure oil to and from the pressure oil supply and discharge object 10. The three-way valve 2 switches between a state in which pressure oil is supplied from the pump 1 to the pressure oil supply and discharge object 10 and a state in which pressure oil is discharged from the pressure oil supply and discharge object 10 to the outside. When the pressure of the pressure oil in the flow path exceeds the set pressure, the pressure protection valve 3 discharges the pressure oil to the outside so that the pressure of the pressure oil in the flow path is below the set pressure. The air flow detection device 5 detects the flow rate of the compressed air supplied to or discharged from the pump 1. The hydraulic pressure detection device 6 detects the pressure of the pressure oil in the flow path.

[0006] The present invention described above has the following operational effects. It includes the above air flow detection device 5 and hydraulic pressure detection device 6. Thereby, an abnormal state that could not be detected in a conventional pressure oil supply and discharge system can be detected by the air flow detection device and the hydraulic pressure detection device 6 in the pressure oil supply and discharge system of the present invention.

[0007] It is preferable to add the following configurations (1) to (3) to the present invention. (1) For example, as shown in FIGS. 1 to 3 or FIG. 4, the air pressure detection device 4 detects the pressure of the compressed air supplied to or discharged from the pump 1. In this case, an abnormal state of the pressure oil supply and discharge system that could not be detected by the air flow detection device and the hydraulic pressure detection device is surely detected by combining the detection results of the air flow detection device, the hydraulic pressure detection device, and the air pressure detection device.

[0008] (2) A control device 80 that receives signals from the air flow detection device 5 and the hydraulic pressure detection device 6 detects the state of the pressure oil supply and discharge system. In this case, the control device surely detects an abnormal state of the pressure oil supply and discharge system that could not be detected from the detection result of only the hydraulic pressure detection device by combining the detection results of the air flow detection device and the hydraulic pressure detection device.

[0009] (3) A control device 80 that receives signals from the air pressure detection device 4, the air flow detection device 5, and the hydraulic pressure detection device 6 detects the state of the pressure oil supply and discharge system. In this case, the control device surely detects an abnormal state of the pressure oil supply and discharge system that could not be detected by only the detection results of the hydraulic pressure detection device and the air flow detection device by combining the detection results of the air flow detection device, the air pressure detection device, and the hydraulic pressure detection device.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0011] The first embodiment of the present invention will be described with reference to FIG. 1. The above-mentioned pressure oil supply and discharge system includes a pump 1, a three-way valve 2, a pressure protection valve 3, an air pressure detection device 4, an air flow detection device 5, and a hydraulic pressure detection device 6.

[0012] Compressed air is supplied to the above-mentioned pump 1 from a compressed air source 7 through a pressure regulator 8. Thereby, the pump 1 supplies the oil in the oil tank 9 to the cylinder (pressure oil supply and discharge object) 10 as pressure oil through a flow path.

[0013] As shown in FIG. 2, the above-mentioned pump 1 is configured as follows. A compressed air supply port 12 and an air discharge hole 13 are provided in the casing 11 of the pump 1. Compressed air from the compressed air source 7 is supplied to the compressed air supply port 12. After the compressed air drives a piston 15 provided in the casing 11, it is discharged to the outside from the air discharge hole 13.

[0014] An oil supply port 17 and a discharge port 18 communicate with a plunger chamber 16 formed in the pump 1. The oil tank 9 communicates with the oil supply port 17 through a flow path 20. A plunger 21 connected to the piston 15 is inserted into the plunger chamber 16 in a sealed state. When the plunger 21 rises, the hydraulic pressure in the plunger chamber 16 decreases, and the oil in the oil tank 9 flows into the plunger chamber 16 from the oil supply port 17 through the flow path 20. When the plunger 21 descends, the pressure oil in the plunger chamber 16 is sent out from the discharge port 18 to the three-way valve 2.

[0015] As shown in Fig. 3, the above-mentioned three-way valve 2 includes a housing 26, a direction switching valve body 27, and a direction switching mechanism 28. A valve chamber 29 is formed vertically within the housing 26. The valve chamber 29 is vertically divided into a first chamber 31 and a second chamber 32 by a partition wall 30 formed inside thereof. The first chamber 31 and the second chamber 32 are connected by a communication hole 33. A supply port 34 is formed in the housing 26, and the supply port 34 communicates with the first chamber 31 via an inlet passage 35. The inlet passage 35 opens to the ceiling surface of the first chamber 31. The supply port 34 is connected to the discharge port 18 of the pump 1. A pressure supply valve seat 36 is formed at the periphery of the opening hole of the inlet passage 35. A check valve body 37 capable of abutting against the pressure supply valve seat 36 is inserted into the first chamber 31 so as to be movable vertically. A closing valve spring 38 is mounted between the lower surface of the check valve body 37 and the upper surface of the partition wall 30. A short-circuit prevention valve seat 39 is formed annularly at the periphery of the opening on the second chamber 32 side of the communication hole 33 formed in the partition wall 30. Further, an outlet passage 40 opens to the bottom surface of the second chamber 32, and a return valve seat 41 is formed annularly at the periphery of the opening. A short-circuit prevention valve body 42 capable of abutting against the short-circuit prevention valve seat 39 is inserted into the second chamber 32 so as to be movable vertically. A return valve body 44 is inserted into a receiving hole 43 formed in the lower part of the short-circuit prevention valve body 42 so as to be movable vertically. Further, a separation spring 45 is mounted in the receiving hole 43, and the separation spring 45 biases the short-circuit prevention valve body 42 and the return valve body 44 in a separating direction. More specifically, the separation spring 45 biases the short-circuit prevention valve body 42 toward the short-circuit prevention valve seat 39 and biases the return valve body 44 toward the return valve seat 41. The second chamber 32 communicates with the working chamber 47 of the cylinder 10 via an operating port 46. Further, the outlet passage 40 communicates with the above-mentioned oil tank 9 via a return port 48.

[0016] The direction switching mechanism 28 is provided below the second chamber 32 and is configured as follows. The second chamber 32 is formed such that the cylinder hole 51 communicates therewith via the outlet passage 40. An output member 52 is inserted into the cylinder hole 51 so as to be movable in the vertical direction. The output member 52 has a piston portion 53 formed in order from the lower side and an operation rod 54 protruding upward from the piston portion 53. The operation rod 54 is inserted into the outlet passage 40 so as to be movable in the vertical direction in a sealed state and can abut against the return valve body 44. An operating chamber 55 for advancement is formed below the piston portion 53, and an operating chamber 56 for retraction is formed above the piston portion 53. A supply and discharge passage 57 for compressed air communicates with the operating chamber 55 for advancement, and compressed air from a compressed air source is supplied to and discharged from the operating chamber 55 for advancement through the supply and discharge passage 57. Further, a return spring 58 is mounted in the operating chamber 56 for retraction, and the return spring 58 biases the output member 52 downward.

[0017] The above pressure safeguard valve 3 is configured to release the abnormal rising pressure to the outside when the hydraulic pressure in the working port 46 abnormally rises due to thermal expansion of the pressure oil, external force, etc., so that the inside of the working port 46 becomes below the set pressure. The above pressure safeguard valve 3 has a valve seat chamber 62, a relief valve chamber 63, and a spring chamber 64 that are coaxially communicated in order from the left side in the valve case 61. The valve seat chamber 62 is connected to the working port 46 of the three-way valve 2 through the flow passage 65. Further, the relief valve chamber 63 is connected to the return port 48 of the three-way valve 2 through the flow passage 66.

[0018] A valve seat member 67 is inserted into the valve seat chamber 62 in a sealed state so as to be movable forward and backward in the left-right direction. A communication hole 68 is formed from the right end surface to the lower surface of the valve seat member 67. A throttle passage 69 is formed by the fitting gap between the outer peripheral surface of the valve seat member 67 and the inner peripheral surface of the valve seat chamber 62. Further, a valve seat 70 is formed at the right end of the valve seat member 67.

[0019] A valve member 71 is inserted into the relief valve chamber 63 so as to be able to advance and retreat in the left - right direction in a sealed manner. An elastic member made of resin or the like is attached to an annular groove formed at the left end of the valve member 71. An annular valve surface 72 is formed at the left end of the elastic member, and the valve surface 72 faces the valve seat 70 so as to be able to come into contact therewith.

[0020] A relief spring 74 and a spring seat are attached between the right end of the spring chamber 64 and the valve member 71. The relief spring 74 biases the valve member 71 to the left.

[0021] In the above - mentioned pressure - maintaining valve 3, when the hydraulic pressure in the valve seat chamber 62 exceeds the pressure corresponding to the biasing force of the relief spring 74, the valve surface 72 is separated from the valve seat 70, and the pressure - maintaining valve 3 is opened. On the contrary, when the hydraulic pressure in the valve seat chamber 62 is lower than the pressure corresponding to the biasing force of the relief spring 74, the relief spring 74 presses the valve surface 72 against the valve seat 70, and the pressure - maintaining valve 3 is closed.

[0022] The above - mentioned pressure - maintaining valve 3 operates as follows. In the initial state of FIG. 3, when pressure oil is supplied from the operating port 46 of the three - way valve 2 to the valve seat chamber 62, the hydraulic pressure in the valve seat chamber 62 moves the valve seat member 67 to the right, and the valve seat member 67 moves the valve member 71 to the right. As a result, a flange portion formed at the left end of the valve seat member 67 is received by a stepped portion in the valve seat chamber 62. Also, the pressure oil in the valve seat chamber 62 presses the valve member 71 to the right through the throttle passage 69 and the communication passage 68 of the valve seat chamber 62, but the valve surface 72 of the valve member 71 is sealingly contacted with the valve seat 70 of the valve seat member 67 by the relief spring 74, and the pressure - maintaining valve 3 remains closed.

[0023] When the hydraulic pressure in the above - mentioned valve seat chamber 62 exceeds the pressure corresponding to the biasing force of the relief spring 74, the pressure - maintaining valve 3 is opened, and the pressure oil in the valve seat chamber 62 is discharged from the relief valve chamber 63, the flow path 66, and the return port 48 of the three - way valve 2 to the oil tank 9. Then, the hydraulic pressure in the valve seat chamber 62 decreases and the hydraulic pressure is lower than the pressure corresponding to the biasing force of the relief spring 74. Then, the pressure - maintaining valve 3 is closed.

[0024] The air pressure detection sensor (air pressure detection device) 4 and the air flow rate detection sensor (air flow rate detection device) 5 are provided in the middle of the flow path connecting the compressed air source 7 and the pump 1. Further, the hydraulic pressure detection sensor 6 is provided in the middle of the flow path connecting the operating port 46 of the three-way valve 2 and the operating chamber 47 of the cylinder 10.

[0025] The pressure oil supply and discharge system of the above embodiment operates as follows. When the compressed air from the above-mentioned compressed air source 7 is supplied into the pump 1 through the compressed air supply port 12 of the pump 1, the compressed air drives the piston 15 in the vertical direction. At this time, the pressure of the compressed air in the flow path connecting the compressed air source 7 and the pump 1 is detected by the air pressure detection sensor 4, and the flow rate of the compressed air in the flow path is detected by the air flow rate detection sensor 5. Then, as the plunger 21 connected to the piston 15 rises, the oil in the oil tank 9 is drawn into the plunger chamber 16 through the flow path 20 and the oil supply port 17, and as the plunger 21 descends, the plunger 21 pushes the oil in the plunger chamber 16 out through the discharge port 18 to the supply port 34 of the three-way valve 2. The pressure oil supplied to the supply port 34 moves the check valve body 37 of the three-way valve 2 downward against the biasing force of the closing valve spring 38 to open the check valve body 37. At this time, no compressed air is supplied to the operating chamber 55 for advancement of the direction switching mechanism 28 of the three-way valve 2, and the piston portion 53 of the output member 52 is moved downward by the biasing force of the return spring 58. For this reason, a gap is formed between the upper end surface of the operation rod 54 of the output member 52 and the lower end surface of the return valve body 44. Next, the pressure oil in the supply port 34 flows into the first chamber 31 of the valve chamber 29. The pressure oil in the first chamber 31 moves the return valve body 44 downward against the biasing force of the separating spring 45 to close the return valve body 44. Then, the pressure oil in the first chamber 31 is supplied to the operating chamber 47 of the cylinder 10 through the communication passage 33, the second chamber 32, and the operating port 46. Then, the piston of the cylinder 10 advances upward. When the piston stops at the upper limit position, the pressure of the pressure oil in the operating chamber 47 rises to a predetermined pressure. The predetermined pressure is detected by the hydraulic pressure detection sensor 6. Then, the pressure in the flow path from the discharge port 18 of the pump 1 to the cylinder 10 becomes higher than the pressure in the plunger chamber 16 of the pump 1, and the pump 1 cannot extrude the pressure oil. As a result, the driving of the piston 15 of the pump 1 stops, and the compressed air from the compressed air source 7 is also not discharged (does not flow) from the inside of the pump 1. At this time, it is detected by the air pressure detection device 4 that the pressure of the compressed air supplied to the pump 1 is higher than the pressure of the compressed air when the compressed air is flowing in the pump 1 (a pressure within a predetermined pressure range).Also, it is detected by the air flow rate detection device 5 that there is no flow of compressed air from the compressed air source 7 to the pump 1 (including the flow path in the pump 1). When it is detected by the detection results of the three detection sensors 4, 5, and 6 that the pressure oil supply and discharge system operates normally, it is detected that the pressure oil supply and discharge system is in a normal state where it supplies pressure oil within a predetermined pressure range to the working chamber 47 of the cylinder 10.

[0026] When the operating state of the pressure oil supply and discharge system is detected by the hydraulic pressure detection sensor 6 and the air flow rate detection sensor 5 among the three detection sensors 4, 5, and 6 provided in the pressure oil supply and discharge system, the combinations of the detection results are as shown in Table 1 below, with a total of four cases.

[0027]

Table 1

[0028] In the conventional pressure oil supply and discharge system, there was no air flow detection sensor and air pressure detection sensor, and only a hydraulic pressure detection switch was provided. For this reason, it was detected by the hydraulic pressure detection switch that the pressure of the pressure oil discharged from the pressure oil supply and discharge system to the cylinder exceeded a predetermined pressure. Based on the detection result, it was determined that the pressure oil supply and discharge system was in a normal state. Also, when it was detected by the hydraulic pressure detection switch that the pressure was below the predetermined pressure, it was determined that the pressure oil supply and discharge system was in an abnormal state. The conventional pressure oil supply and discharge system is excellent in that it can confirm that the pressure oil of an appropriate pressure is supplied to the cylinder. However, even when the pressure oil supply and discharge system supplies the cylinder with pressure oil of an appropriate pressure, there may be an abnormal state in which the component devices such as pumps and peripheral devices are driven excessively, or an abnormal state in which the peripheral devices are used while being worn or slightly damaged. The conventional pressure oil supply and discharge system cannot detect such an abnormal state. Continuing to use in such an abnormal state for a long time may lead to significant damage due to accelerated aging. In the pressure oil supply and discharge system of the present embodiment, the above state (the state of (2) in Table 1 above or the state of (1)-2 in Table 2) or a case where there is a possibility of such a state is also regarded as an abnormal state of the pressure oil supply and discharge system including the possibility of a defect. The abnormal state is detected by combining the detection result of the air flow detection sensor 5 and the detection result of the hydraulic pressure detection sensor 6, etc.

[0029] In the pressure oil supply and discharge system of the present embodiment, first, the abnormal or normal state of the pressure oil supply and discharge system is determined by combining the detection results of the two detection sensors, namely, the hydraulic pressure detection sensor 6 and the air flow detection sensor 5, among the above three detection sensors 4, 5, and 6.

[0030] In (1) of Table 1 above, it is detected by the hydraulic pressure detection sensor 6 that the pressure of the pressure oil in the flow path connecting the three-way valve 2 and the cylinder 10 is within a predetermined pressure range. Further, it is detected by the air flow rate detection sensor 5 that no compressed air is flowing in the flow path connecting the compressed air source 7 and the pump 1. By combining the detection result of the hydraulic pressure detection sensor 6 and the detection result of the air flow rate detection sensor 5, it can be seen that the pressure oil supply and discharge system is in a normal state.

[0031] In (2) of Table 1 above, it is detected by the hydraulic pressure detection sensor 6 that the pressure of the pressure oil in the flow path connecting the three-way valve 2 and the cylinder 10 is within a predetermined pressure range. Further, it is detected by the air flow rate detection sensor 5 that compressed air is flowing in the flow path connecting the compressed air source 7 and the pump 1. Here, in the conventional pressure oil detection system having only a hydraulic pressure detection switch, it has been determined to be in a normal state from the detection result of the hydraulic pressure detection switch. However, in the pressure oil supply and discharge system of the present embodiment, by combining the detection result of the hydraulic pressure detection sensor 6 and the detection result of the air flow rate detection sensor 5, it can be seen that the pressure oil supply and discharge system is in an abnormal state. When such a detection result is obtained, it is presumed that the pressure oil supply and discharge system is in a state where the pressure oil leaks from the three-way valve 2, the pressure protection valve 3, the piping, etc. to the oil tank 9 or to the outside (gently to maintain the predetermined pressure range) and the pump 1 is driven little by little. Or, it is presumed that the pressure oil supply and discharge system is in a state where compressed air at a pressure higher than the desired pressure is supplied to the pump 1 due to a failure of the pressure regulator 8 or a poor pressure adjustment of the pressure regulator 8, and the pump 1 is driven little by little. Such a state, if it is for a short period, is less likely to immediately lead to wear and failure of the components of the pressure oil supply and discharge system, but if such a state continues for a long period, it may lead to wear and failure of the components. Therefore, it is determined that the pressure oil supply and discharge system is in an abnormal state as there is a defect or a risk of a defect.

[0032] In (3) and (4) of Table 1 above, it is detected by the hydraulic pressure detection sensor 6 that the pressure of the pressure oil in the flow path connecting the three-way valve 2 and the cylinder 10 is outside the predetermined pressure range (higher or lower than the predetermined pressure range). Further, in (3) of Table 1, it is detected by the air flow rate detection sensor 5 that no compressed air is flowing in the flow path connecting the compressed air source 7 and the pump 1. In (4) of Table 1, it is detected by the air flow rate detection sensor 5 that compressed air is flowing in the flow path connecting the compressed air source 7 and the pump 1. In this case, in both the conventional pressure oil detection system having only the hydraulic pressure detection switch described above and the pressure oil supply and discharge system of the present embodiment, it is determined that an abnormal state exists based on the detection result of the hydraulic pressure detection sensor 6. However, in the pressure oil supply and discharge system of the present embodiment, the difference in the detection results of the air flow rate detection sensor 5, that is, the abnormal state when no compressed air is flowing in the flow path ((3) in Table 1 above) and the abnormal state when it is flowing ((4) in Table 1 above), the presumed abnormal states of the pressure oil supply and discharge system are different. First, in (3) of Table 1, the following abnormal states can be considered. It is presumed that some external force is acting on the output rod of the cylinder 10 and the pressure in the flow path of the pressure oil is rising. Or, it is presumed that the temperature of the pressure oil is rising, the pressure oil in the flow path is thermally expanded, and the pressure of the flow path is rising. Or, due to a failure or poor adjustment of the compressed air source 7 or the pressure regulator 8, the pump 1 cannot operate normally, and it is presumed that the pressure in the flow path of the pressure oil is below the predetermined pressure range.

[0033] Next, in (4) of Table 1 above, the following abnormal states different from (3) are presumed. It is presumed that pressure oil is leaking from the three-way valve 2 or the pressure safeguard valve 3 and the pump 1 is being driven little by little. Or, due to a failure of the compressed air source 7 or the pressure regulator 8, high-pressure compressed air is supplied and the pump 1 is operating little by little, and it is presumed that the pressure in the flow path of the pressure oil exceeds the predetermined pressure range.

[0034] In a conventional pressure oil supply and discharge system equipped only with a hydraulic pressure detection switch, it was not possible to analyze and infer an abnormal state in detail. In contrast, in the pressure oil supply and discharge system of the present embodiment equipped with a hydraulic pressure detection sensor 6 and an air flow rate detection sensor 5, by combining the detection results of the hydraulic pressure detection sensor 6 and the detection results of the air flow rate detection sensor 5, it is possible to infer an abnormal state of the pressure oil supply and discharge system according to the combined result.

[0035] Further, by providing an air pressure detection sensor 4 in addition to the above two detection sensors 5 and 6, the following states of the pressure oil supply and discharge system are detected.

[0036]

Table 2

[0037] In (1)-1 in Table 2 above, the hydraulic pressure detection sensor 6 detects that the pressure of the pressure oil in the flow path connecting the three-way valve 2 and the cylinder 10 is within a predetermined pressure range. Also, the air flow rate detection sensor 5 detects that no compressed air is flowing in the flow path connecting the compressed air source 7 and the pump 1. Further, the air pressure detection sensor 4 detects that the pressure of the compressed air in the flow path connecting the compressed air source 7 and the pump 1 is within a predetermined pressure range. By combining the detection results of the hydraulic pressure detection sensor 6, the air flow rate detection sensor 5, and the air pressure detection sensor 4, it can be seen that the pressure oil supply and discharge system is in a normal state.

[0038] In (1)-2 of Table 2 above, it is detected by the hydraulic pressure detection sensor 6 that the pressure of the pressure oil in the flow path connecting the three-way valve 2 and the cylinder 10 is within a predetermined pressure range. Further, it is detected by the air flow rate detection sensor 5 that no compressed air is flowing in the flow path connecting the compressed air source 7 and the pump 1. Further, it is detected by the air pressure detection sensor 4 that the pressure of the compressed air in the flow path connecting the compressed air source 7 and the pump 1 is outside the predetermined pressure range. Here, in the above-described pressure oil detection system having two detection sensors 5 and 6, the state of (1)-2 in Table 2 above was determined to be a normal state based on the detection result of the hydraulic pressure detection sensor 6 and the detection result of the air flow rate detection sensor 5. However, in the pressure oil supply / discharge system of the present embodiment, by combining the detection result of the hydraulic pressure detection sensor 6, the detection result of the air flow rate detection sensor 5, and the detection result of the air pressure detection sensor 4, it can be seen that the pressure oil supply / discharge system is in an abnormal state. When such a detection result is obtained, after the pressure oil supply / discharge system supplies pressure oil within a predetermined pressure range to the cylinder 10, due to looseness of the joint, deterioration, wear, breakage, etc. of the piping and the pump 1, it is presumed that the compressed air has leaked from the flow path connecting the compressed air source 7 and the pump 1 (including the flow path in the pump). Such a state is less likely to immediately lead to wear or failure of the components of the pressure oil supply / discharge system in a short period, but if such a state continues for a long time, it may lead to wear or failure of the components. Therefore, it is determined that the pressure oil supply / discharge system is in an abnormal state as there is a defect or a risk of a defect.

[0039] In (2)-1 of Table 2 above, it is detected by the hydraulic pressure detection sensor 6 that the pressure of the pressure oil in the flow path connecting the three-way valve 2 and the cylinder 10 is within a predetermined pressure range. Also, it is detected by the air flow rate detection sensor 5 that compressed air is flowing in the flow path connecting the compressed air source 7 and the pump 1. Further, it is detected by the air pressure detection sensor 4 that the pressure of the compressed air in the flow path connecting the compressed air source 7 and the pump 1 is within a predetermined pressure range. By combining the detection results of the hydraulic pressure detection sensor 6, the air flow rate detection sensor 5, and the air pressure detection sensor 4, it can be known that the pressure oil supply and discharge system is in an abnormal state. When such detection results are obtained, it is presumed that the pressure oil supply and discharge system is in a state where pressure oil is leaking from the three-way valve 2, the pressure safeguard valve 3, the piping, etc. to the oil tank 9 or externally (gently to maintain the predetermined pressure range), and the pump 1 is being driven little by little.

[0040] In (2)-2 of Table 2 above, it is detected by the hydraulic pressure detection sensor 6 that the pressure of the pressure oil in the flow path connecting the three-way valve 2 and the cylinder 10 is within a predetermined pressure range. Also, it is detected by the air flow rate detection sensor 5 that compressed air is flowing in the flow path connecting the compressed air source 7 and the pump 1. Further, it is detected by the air pressure detection sensor 4 that the pressure of the compressed air in the flow path connecting the compressed air source 7 and the pump 1 is outside the predetermined pressure range. By combining the detection results of the hydraulic pressure detection sensor 6, the air flow rate detection sensor 5, and the air pressure detection sensor 4, it can be known that the pressure oil supply and discharge system is in an abnormal state. When such detection results are obtained, it is presumed that the pressure oil supply and discharge system is in a state where compressed air at a pressure higher than the desired pressure is being supplied to the pump 1 due to a failure of the compressed air source 7 or the pressure regulator 8, or poor pressure adjustment of the pressure regulator 8, and the pump 1 is being driven little by little.

[0041] In (3)-1 of Table 2 above, the hydraulic pressure sensor 6 detects that the pressure of the pressure oil in the flow path connecting the three-way valve 2 and the cylinder 10 is outside the predetermined pressure range (higher or lower than the predetermined pressure range). Also, the air flow rate detection sensor 5 detects that no compressed air is flowing in the flow path connecting the compressed air source 7 and the pump 1. Further, the air pressure detection sensor 4 detects that the pressure of the compressed air in the flow path connecting the compressed air source 7 and the pump 1 is within the predetermined pressure range. By combining the detection results of the hydraulic pressure detection sensor 6, the air flow rate detection sensor 5, and the air pressure detection sensor 4, it can be seen that the pressure oil supply and discharge system is in an abnormal state. When such detection results are obtained, it is presumed that the pressure oil supply and discharge system is in a state where some external force is acting on the output rod of the cylinder 10, causing the pressure in the flow path of the pressure oil to rise. Or it is presumed that the temperature of the pressure oil has risen, causing the pressure oil in the flow path to thermally expand and the pressure in the flow path to rise.

[0042] In (3)-2 of Table 2 above, the hydraulic pressure sensor 6 detects that the pressure of the pressure oil in the flow path connecting the three-way valve 2 and the cylinder 10 is outside the predetermined pressure range (higher or lower than the predetermined pressure range). Also, the air flow rate detection sensor 5 detects that no compressed air is flowing in the flow path connecting the compressed air source 7 and the pump 1. Further, the air pressure detection sensor 4 detects that the pressure of the compressed air in the flow path connecting the compressed air source 7 and the pump 1 is outside the predetermined pressure range. By combining the detection results of the hydraulic pressure detection sensor 6, the air flow rate detection sensor 5, and the air pressure detection sensor 4, it can be seen that the pressure oil supply and discharge system is in an abnormal state. When such detection results are obtained, it is presumed that the pressure oil supply and discharge system is in a state where, due to a failure of the compressed air source 7 or the pressure regulator 8, or poor pressure adjustment of the pressure regulator 8, compressed air at a pressure lower than the desired pressure is being supplied to the pump 1, and the pump 1 is not operating normally.

[0043] In (4)-1 of Table 2 above, it is detected by the hydraulic pressure detection sensor 6 that the pressure of the pressure oil in the flow path connecting the three-way valve 2 and the cylinder 10 is outside the predetermined pressure range (higher or lower than the predetermined pressure range). Also, it is detected by the air flow rate detection sensor 5 that compressed air is flowing in the flow path connecting the compressed air source 7 and the pump 1. Further, it is detected by the air pressure detection sensor 4 that the pressure of the compressed air in the flow path connecting the compressed air source 7 and the pump 1 is within the predetermined pressure range. By combining the detection results of the hydraulic pressure detection sensor 6, the air flow rate detection sensor 5, and the air pressure detection sensor 4, it can be understood that the pressure oil supply and discharge system is in an abnormal state. When such detection results are obtained, it is presumed that the pressure oil supply and discharge system is in a state where pressure oil is leaking from the three-way valve 2 or the pressure safeguard valve 3 and the pump 1 is being driven little by little.

[0044] In (4)-2 of Table 2 above, it is detected by the hydraulic pressure detection sensor 6 that the pressure of the pressure oil in the flow path connecting the three-way valve 2 and the cylinder 10 is outside the predetermined pressure range (higher or lower than the predetermined pressure range). Also, it is detected by the air flow rate detection sensor 5 that compressed air is flowing in the flow path connecting the compressed air source 7 and the pump 1. Further, it is detected by the air pressure detection sensor 4 that the pressure of the compressed air in the flow path connecting the compressed air source 7 and the pump 1 is outside the predetermined pressure range. By combining the detection results of the hydraulic pressure detection sensor 6, the air flow rate detection sensor 5, and the air pressure detection sensor 4, it can be understood that the pressure oil supply and discharge system is in an abnormal state. When such detection results are obtained, it is presumed that the pressure oil supply and discharge system is in a state where high-pressure compressed air is supplied due to a failure of the compressed air source 7 or the pressure regulator 8, the pump 1 is moving little by little, and the pressure in the flow path of the pressure oil exceeds the predetermined pressure range.

[0045] In the above-described pressure oil supply and discharge system, lamps 75, 76, and 77 are respectively connected to the three detection sensors 4, 5, and 6. When the hydraulic pressure detection sensor 6 detects that the pressure of the pressure oil in the flow path is within a predetermined pressure range, lamp 77 lights up, and when it is higher or lower than the predetermined range, it goes out. When the air flow rate detection sensor 5 detects that no compressed air is flowing in the flow path connecting the compressed air source 7 and the pump 1 (including the flow path in the pump 1), lamp 76 lights up, and when it detects that the compressed air is flowing, it goes out. When the air pressure detection sensor 4 detects that the pressure of the compressed air in the flow path is within a predetermined pressure range, lamp 75 lights up, and when it detects that the pressure is lower or higher than the predetermined pressure range, it goes out. The operator can confirm that the pressure oil supply and discharge system is in a normal state by the fact that the three lamps 75, 76, and 77 are lit. Also, when any one of the three lamps 75, 76, and 77 is off, the operator can confirm that the pressure oil supply and discharge system is in an abnormal state.

[0046] The above-described embodiment has the following advantages. In the conventional pressure oil supply and discharge system and the pressure oil supply and discharge system of the first embodiment, even in a state that has been determined to be a normal state, it is possible to detect that the pressure oil supply and discharge system is in an abnormal state by combining the detection results of the three detection sensors 4, 5, and 6. Also, compared to the presumed abnormal states in the conventional pressure oil supply and discharge system and the pressure oil supply and discharge system of the first embodiment, in the presumed abnormal state of the pressure oil supply and discharge system of this embodiment, it is segmented into more detailed events, so it is easier for the operator performing repair and maintenance to identify the defective part.

[0047] FIG. 4 shows a second embodiment of the present invention. In this second embodiment, the same members (or similar members) as those of the above-described first embodiment are generally denoted by the same reference numerals for description.

[0048] The pressure oil supply and discharge system of the second embodiment of the present invention includes a control device 80. The control device 80 is connected to the air pressure detection sensor 4, the air flow detection sensor 5, and the hydraulic pressure detection sensor 6 by an electric signal line or the like, and can receive electric signals from each of the sensors 4, 5, and 6. The control device 80 includes a storage unit 81 that receives and stores information on whether each of the sensors 4, 5, and 6 is in a normal state (within a predetermined pressure range or no compressed air is flowing) or an abnormal state (outside the predetermined pressure range or compressed air is flowing), an arithmetic unit 82 that compares the information stored in advance in the storage unit 81 with the information based on the signals from each of the sensors 4, 5, and 6, and a display unit 83 that displays the comparison result by the arithmetic unit 82 and other information. Instead of the control device 80 and each of the sensors 4, 5, and 6 being connected by a signal line (wired) such as electricity or light in the present embodiment, they may be connected by wireless such as radio waves.

[0049] The arithmetic unit 82 of the control device 80 compares the information on whether it is normal or abnormal received from each of the sensors 4, 5, and 6 with the information stored in advance in the storage unit 81, and from the comparison result, the display unit 83 displays the presumed abnormal state of the pressure oil supply and discharge system as shown in Table 2 above. Note that a countermeasure method (maintenance method, repair location information, repair method) for the presumed abnormal state may be displayed on the display unit 83.

[0050] In the pressure oil supply and discharge system of this embodiment, in addition to the above three detection sensors 4, 5, and 6, another hydraulic pressure detection sensor 85 and a liquid level detection sensor 86 are provided. The hydraulic pressure detection sensor 85 is provided in a flow path connecting the discharge port 18 of the pump 1 and the supply port 34 of the three-way valve 2, and detects the pressure of the pressure oil in the flow path. By comparing the detection results of the hydraulic pressure detection sensor 85 and the hydraulic pressure detection sensor 6, it is possible to detect whether there is a problem in the pump 1 or whether there is a problem between the three-way valve 2, the pressure protection valve 3, and the cylinder 10. Further, the liquid level detection sensor 86 is provided in the oil tank 9 and detects the height of the oil level in the oil tank 9. When it is detected by the other detection sensors 4, 5, and 6 that there is a leak from the three-way valve 2, the pressure protection valve 3, the piping, etc., it is possible to detect from the detection result of the liquid level detection sensor 86 whether the leaked oil has returned to the oil tank 9 or has flowed out to the outside. These detection sensors 85 and 86 are electrically connected to the control device 80, and the control device 80 receives the detection results of the detection sensors 85 and 86 as signals such as electrical signals.

[0051] The pressure oil supply and discharge system of the second embodiment may be mounted on an injection molding machine, a press device, a machine tool, or the like. In this case, the pressure oil supply and discharge system of this embodiment supplies pressure oil to a cylinder 10 or the like that constitutes a clamp device for fixing a mold or a workpiece. In the cylinder 10 of the clamp device, after the control device determines that the pressure oil supply and discharge system is in a normal state based on the detection results of the air pressure detection sensor 4, the air flow rate detection sensor 5, and the hydraulic pressure detection sensor 6, an external force in the retracting direction may act on the output rod of the cylinder 10. For example, in a clamp device for fixing a mold of an injection molding machine or the like, when the mold is opened, an external force (mold opening force) may act on the clamp device. In this case, the control device can calculate the magnitude of the external force, and the procedure is as follows.

[0052] First, the detection pressure information (pressure value) of the hydraulic pressure detection sensor 6 in the normal state of the pressure oil supply and discharge system (the state shown in (1)-1 of Table 2 above) is transmitted to the control device 80. The detected pressure information is stored in the storage unit 81 as reference pressure information. Note that the information acquisition time and temperature information may also be stored together with the detected pressure information. Next, when an external force acts on the output rod of the cylinder 10 in the retracting direction, the pressure in the working chamber 47 of the cylinder 10 and the pressure in the flow path increase. When the detected pressure exceeds a predetermined pressure range, the pressure oil supply and discharge system enters an abnormal state (for example, the state shown in (3)-1 of Table 2 above). The detection pressure information of the hydraulic pressure detection sensor 6 and the like is transmitted to the control device 80 at predetermined intervals and stored in the storage unit 81 each time. The storage unit 81 stores calculated external force information calculated from the pressure in the working chamber 47 (taking into account the cross-sectional area ratio of the piston and the output rod, etc.). The calculation unit 82 compares the detected pressure information with the calculated external force information, selects the calculated external force information corresponding to the detected pressure, and causes the selected information to be displayed on the display unit 83. As a result, the operator can know the magnitude of the calculated external force. Here, instead of the calculation unit 82 sending the calculated external force information to the display unit 83 and displaying it on the display unit 83, the calculation unit 82 may send the calculated external force information to the control device of the injection molding machine or the like and display it on the display unit of the control device, or send it to another terminal device and display it. Note that the calculated external force information may be a measured value obtained by previously measuring information, for example, the pressure of the pressure oil in the flow path corresponding to the magnitude of the external force, instead of being calculated from the pressure in the working chamber 47.

[0053] Each of the above embodiments can be modified as follows. Instead of the pressure oil supply and discharge system of the second embodiment above including the control device 80, it may be electrically connected wirelessly or by wire to a control device provided in another system connected to the pressure oil supply and discharge system of this embodiment. Instead of, or in addition to, the above detection sensor, a temperature detection sensor for detecting the temperature of the pressure oil or the like, a vibration detection sensor for detecting the vibration of the pump or the like, and the like may be provided. Instead of the air flow detection sensor 5 being provided in the flow path connecting the compressed air source 7 and the pump 1, it may be provided inside the pump 1 or at the air discharge hole 13 of the pump 1. Of course, various modifications can be made within the scope that can be inferred by those skilled in the art.

Explanation of Signs

[0054] 1: Pump, 2: Three-way valve, 3: Pressure safeguard valve, 4: Air pressure detection sensor (air pressure detection device), 5: Air flow detection sensor (air flow detection device), 6: Hydraulic pressure detection sensor (hydraulic pressure detection device), 10: Cylinder (hydraulic oil supply / discharge target object), 80: Control device.

Claims

1. A pump (1) driven by the supply of compressed air, the pump (1) supplying pressure oil to a pressure oil supply / discharge object (10); a three-way valve (2) that is provided in a flow path that supplies and discharges pressure oil to the pressure oil supply / discharge object (10) and that switches between a state in which pressure oil is supplied from the pump (1) to the pressure oil supply / discharge object (10) and a state in which pressure oil is discharged from the pressure oil supply / discharge object (10) to the outside; a pressure compensation valve (3) that discharges the pressure oil to the outside when the pressure of the pressure oil in the flow path exceeds a predetermined pressure so that the pressure of the pressure oil in the flow path falls below the predetermined pressure; an air flow rate detection device (5) that detects the flow rate of compressed air supplied to the pump (1) or discharged from the pump (1); a hydraulic pressure detection device (6) for detecting the pressure of the hydraulic oil in the flow path; The oil pressure detection device (6) detects that the pressure of the pressure oil in the flow path is within a predetermined pressure range, and the air flow detection device (5) detects that there is no flow of compressed air being supplied to the pump (1) or discharged from the pump (1). Based on these two detection results, it is detected that the pump (1) is in a normal state where it is stopped after supplying pressure oil to the pressure oil supply / discharge object (10). A pressurized oil supply and discharge system.

2. The pressure oil supply and discharge system according to claim 1, A pressurized oil supply and discharge system comprising an air pressure detection device (4) that detects the pressure of compressed air supplied to the pump (1) or discharged from the pump (1).

3. The pressure oil supply and discharge system according to claim 1, and a control device (80) that receives signals from the air flow rate detection device (5) and the oil pressure detection device (6) to detect a state of the pressure oil supply / discharge system. A pressurized oil supply and discharge system.

4. The pressure oil supply and discharge system according to claim 2, a control device (80) that receives signals from the air pressure detection device (4), the air flow rate detection device (5), and the oil pressure detection device (6) to detect the state of the pressure oil supply / discharge system; A pressurized oil supply and discharge system.

Images