JP6864507B2 - Seal condition detector - Google Patents

Description

The present invention relates to a seal state detecting device used in a fluid pressure device.

A fluid pressure device having a shaft that slides or rotates in the axial direction usually includes a sealing member that contacts the outer peripheral surface of the shaft in order to prevent fluid from leaking to the outside along the outer peripheral surface of the shaft. There is. Such a sealing member may deteriorate in sealing performance over time and cause fluid leakage.

Patent Document 1 discloses a fluid leakage detection device that detects whether or not a fluid leakage has occurred due to deterioration of the sealing member. In this fluid leakage detection device, it is determined that a fluid leakage has occurred when the amount of fluid accumulated in the measuring unit provided below the cylinder end exceeds the reference value.

Japanese Unexamined Patent Publication No. 06-207608

However, in the fluid leakage detection device described in Patent Document 1, the fluid leakage is determined after the fluid leaks to the outside of the fluid pressure device due to the deterioration of the seal member. After the fluid leakage occurs in this way, it becomes difficult to avoid malfunction of the fluid pressure device, and there is a possibility that the mechanical device in which the fluid pressure device is used must be suddenly stopped.

The present invention has been made in view of the above problems, and an object of the present invention is to detect deterioration of a sealing member before a fluid leak occurs in a fluid pressure device.

The first invention is a seal state detection device for detecting a seal state of a seal member provided in a compressed state between a shaft and a housing that slides and supports the shaft, wherein the outer peripheral surface of the seal member and the housing. Deterioration of the seal member is determined based on the tension force detecting unit provided between the inner peripheral surface and detecting the tension force of the seal member in the radial direction and the tension force of the seal member detected by the tension force detection unit. A deterioration determination unit is provided, and the seal member has a main seal on which the pressure of the working fluid acts directly, and a sub-seal arranged at a predetermined distance from the main seal in the axial direction of the shaft, and is tense. The force detection unit is arranged so as to detect only the tension of the sub-seal among the main seal and the sub-seal, and the deterioration determination unit is based on the tension of the sub-seal detected by the tension detection unit, and the main seal and the sub-seal. It is characterized in that the deterioration of the sub-seal is determined. The second invention is a seal state detection device for detecting a seal state of a seal member provided in a compressed state between a shaft and a housing that slides and supports the shaft, and is provided on the outer peripheral side of the seal member. Deterioration that is provided integrally with the seal member and determines the deterioration of the seal member based on the tension force detection unit that detects the tension force of the seal member in the radial direction and the tension force of the seal member detected by the tension force detection unit. A determination unit is provided, and the seal member has a main seal on which the pressure of the working fluid acts directly, and a sub-seal arranged at a predetermined distance from the main seal in the axial direction of the shaft, and detects tension. The part is arranged so as to detect only the tense force of the sub-seal among the main seal and the sub-seal, and the deterioration determination part is based on the tense force of the sub-seal detected by the tense force detection part of the main seal and the sub-seal. It is characterized by determining deterioration.

In the first and second inventions, the presence or absence of deterioration of the seal member is determined based on the tension force of the seal member detected by the tension force detection unit. In this way, by monitoring whether or not the sealing member is in a state where it can exert the sealing function, it is possible to detect the deterioration of the sealing member before the fluid leakage occurs in the fluid pressure device. Further, in the first and second inventions, the tension force detecting unit detects the tension force of the sub-seal. Since the pressure of the working fluid does not act directly on the sub-seal, the tension force of the detected sub-seal has a stable value with relatively little fluctuation. Therefore, by determining the deterioration of the seal member based on the tense force of the sub-seal, the accuracy of determining the deterioration of the seal member can be improved.

The third invention is characterized in that the tension detection unit is provided in an annular shape along the outer peripheral surface of the seal member.

In the third invention, the tension detection unit is provided in an annular shape along the outer peripheral surface of the seal member. Therefore, a value obtained by averaging the tense force in the radial direction of the seal member over the entire circumference is obtained. As described above, in the seal state detection device, the deterioration of the seal member is determined based on the average tense force, so that the deterioration determination accuracy can be improved.

The fourth invention is characterized in that a plurality of tension force detecting units are provided along the outer peripheral surface of the seal member.

In the fourth invention, a plurality of tension force detecting portions are provided along the outer peripheral surface of the seal member. Therefore, by grasping the tense force detected by each tense force detecting unit, it is possible to identify in which part of the seal member the deterioration has occurred.

A fifth aspect of the present invention is characterized in that the tension detection unit is provided in a part along the outer peripheral surface of the sealing member.

In the fifth invention, the tension detection unit is provided in a part along the outer peripheral surface of the seal member. By reducing the range in which the tension force detection unit is provided and providing the tension force detection unit in the portion where deterioration is likely to occur, the manufacturing cost of the seal state detection device can be reduced and the deterioration determination accuracy can be improved. Can be improved.

According to a sixth aspect of the present invention, the sealing member extends axially from the base portion, the first lip portion extending axially from the base portion and contacting the inner peripheral surface of the housing, and the outer peripheral surface of the shaft extending axially from the base portion. It has two lip portions, and the tension detecting portion is arranged closer to the base portion than the contact portion between the first lip portion and the housing.

In the sixth invention, the tension detection unit is arranged closer to the base portion than the portion where the first lip portion and the housing are in contact with each other. In this way, the tension detection unit is arranged so as not to interfere with the sealing function of the first lip unit. Therefore, the seal member can surely prevent the fluid from leaking to the outside even if the tension detection unit is provided.

In the seventh invention, the tension detecting unit has a pair of electrodes and a pressure-sensitive conductive rubber sandwiched between the pair of electrodes, and the resistance value between the pair of electrodes determines the tension of the sealing member. It is characterized by changing accordingly.

In the seventh invention, the tension detecting unit has a pair of electrodes and a pressure-sensitive conductive rubber sandwiched between the pair of electrodes. As described above, since the tension force detecting unit has a simple structure, its molding can be easily performed. Therefore, even when the tension detection unit is provided in a wide range along the outer peripheral surface of the seal member, it is possible to suppress an increase in the manufacturing cost of the seal state detection device.

In the eighth invention, when the deterioration determination unit determines that the tension of the sub-seal detected by the tension detection unit is smaller than the preset first reference value, it determines that the sub-seal has deteriorated, and the deterioration is determined from the first reference value. If it is larger than the second reference value, which is also large, it is determined that the main seal has deteriorated.

In the eighth invention, when the tension force of the sub-seal detected by the tension force detection unit is smaller than the preset first reference value, it is determined that the sub-seal has deteriorated, and when it is larger than the second reference value. It is determined that the main seal has deteriorated. By monitoring the tense force of the sub-seal in this way, it is possible to detect the deterioration of the seal member before the hydraulic oil leaks in the fluid pressure device, and it is possible to determine which of the main seal and the sub-seal has deteriorated. can do.

According to the present invention, deterioration of the sealing member can be detected before fluid leakage occurs in the fluid pressure device.

It is sectional drawing of the hydraulic cylinder which uses the seal state detection apparatus which concerns on embodiment of this invention. It is an enlarged sectional view which shows the part where the seal state detection apparatus which concerns on embodiment of this invention is provided. It is sectional drawing which follows the line III-III of FIG. It is an enlarged cross-sectional view which shows the seal member provided with the tension force detection part in an enlarged manner. It is sectional drawing of the tension force detection part. It is a graph for demonstrating the determination of the deterioration of a seal member based on the tense force of a seal member. It is sectional drawing which shows the 1st modification of the tension force detection part. It is sectional drawing which shows the 2nd modification of the tension force detection part. It is sectional drawing which shows the 3rd modification of the tension force detection part.

Hereinafter, the seal state detection device 100 and the fluid pressure device including the seal state detection device 100 according to the embodiment of the present invention will be described with reference to the drawings. Hereinafter, a case where the hydraulic pressure device is a hydraulic cylinder 1 driven by using hydraulic oil as a hydraulic fluid will be described. FIG. 1 is a cross-sectional view showing a hydraulic cylinder 1. FIG. 2 is an enlarged cross-sectional view showing the periphery of the portion where the seal state detection device 100 is provided. In FIG. 1, the seal state detection device 100 is not shown.

As shown in FIGS. 1 and 2, the hydraulic cylinder 1 includes a tubular cylinder tube 2, a piston rod 3 as a shaft inserted into the cylinder tube 2, and a base end of the piston rod 3 (right end in FIG. 1). A piston 4 that is connected to and slides along the inner peripheral surface of the cylinder tube 2 is provided.

The inside of the cylinder tube 2 is partitioned by a piston 4 into two hydraulic chambers, a rod side chamber 5 and an anti-rod side chamber 6. The hydraulic cylinder 1 expands and contracts by the hydraulic pressure guided from a hydraulic source (not shown) to the rod side chamber 5 or the anti-rod side chamber 6. The inner circumference of the cylinder tube 2 and the outer circumference of the piston 4 are sealed by a sealing member (not shown). As a result, the communication between the rod side chamber 5 and the anti-rod side chamber 6 through the inner circumference of the cylinder tube 2 and the outer circumference of the piston 4 is cut off.

The cylinder tube 2 is provided with a cylinder head 7 as a housing that closes the open end of the cylinder tube 2 and slidably supports the piston rod 3. The cylinder head 7 is fastened to the cylinder tube 2 via a plurality of fastening bolts (not shown) arranged in the circumferential direction.

As shown in FIG. 2, bushes 9, seal members 10, and dust seals 13 are provided on the inner circumference of the cylinder head 7 in this order from the rod side chamber 5 side to the outside.

The bush 9 is arranged so as to be in sliding contact with the outer peripheral surface 3a of the piston rod 3. Therefore, the piston rod 3 is slidably supported by the cylinder head 7 via the bush 9, and can move along the axial direction of the cylinder tube 2.

The seal member 10 prevents the hydraulic oil in the rod side chamber 5 from leaking to the outside, and is arranged on the bush 9 side and directly acts on the pressure of the hydraulic oil in the rod side chamber 5 and the piston rod. It has a main seal 11 and a sub-seal 12 arranged at a predetermined interval in the axial direction of 3. The main seal 11 and the sub seal 12 are U-packings having a U-shaped cross section, and are arranged in a groove formed in the cylinder head 7 in a compressed state between the piston rod 3 and the cylinder head 7. Cylinder. When the hydraulic oil leaks from the gap between the main seal 11 and the piston rod 3 due to deterioration of the main seal 11, the sub-seal 12 prevents the hydraulic oil from leaking to the outside.

The dust seal 13 prevents dust from entering the cylinder tube 2 from the outside, and like the main seal 11 and the sub seal 12, the cylinder is compressed between the piston rod 3 and the cylinder head 7. It is arranged in the groove formed in the head 7.

In the hydraulic cylinder 1 having the above configuration, when the rod side chamber 5 is communicated with the hydraulic source and the anti-rod side chamber 6 is communicated with a tank (not shown), hydraulic oil is supplied to the rod side chamber 5 and the hydraulic oil in the anti-rod side chamber 6 is supplied. Is discharged to the tank, and the hydraulic cylinder 1 contracts. On the other hand, when the anti-rod side chamber 6 is communicated with the hydraulic source and the rod side chamber 5 is communicated with the tank, the hydraulic oil is supplied to the anti-rod side chamber 6 and the hydraulic oil in the rod side chamber 5 is discharged to the tank. , The hydraulic cylinder 1 is extended.

Further, the above-mentioned hydraulic cylinder 1 incorporates a seal state detection device 100 that detects the seal state of the seal member 10. The seal state detection device 100 will be described below with reference to FIGS. 2 to 5. FIG. 3 is a cross-sectional view of the hydraulic cylinder 1 in a portion where the tension force detection unit 20 described later is provided, and FIG. 4 is an enlarged cross-sectional view showing the portion where the tension force detection unit 20 is provided in an enlarged manner. FIG. 5 is a cross-sectional view showing a cross section of the tension force detecting unit 20.

As shown in FIG. 2, the seal state detection device 100 is based on the tension force detection unit 20 provided between the sub-seal 12 and the cylinder head 7 and the tension force of the sub-seal 12 detected by the tension force detection unit 20. It has a deterioration determination unit 30 for determining deterioration of the seal member 10. The tension force detecting unit 20 detects the tension force in the radial direction of the sub-seal 12, and is provided in an annular shape along the outer peripheral surface of the sub-seal 12 as shown in FIG.

Here, as shown in an enlarged manner in FIG. 4, the above-mentioned sub-seal 12 is arranged in the annular groove 8 formed in the cylinder head 7, and is formed from the base portion 12a and the base portion 12a formed in an annular shape. It has a first lip portion 12b extending axially and contacting the first bottom surface 8a of the annular groove 8, and a second lip portion 12c extending axially from the base portion 12a and contacting the outer peripheral surface 3a of the piston rod 3.

Further, the annular groove 8 has a depth deeper than that of the first bottom surface 8a, and has a second bottom surface 8b formed on the base portion 12a side of the sub-seal 12 continuously with the first bottom surface 8a. The tension detection unit 20 is arranged between the second bottom surface 8b and the portion of the sub-seal 12 near the base portion 12a.

In this way, the tension detection unit 20 is arranged closer to the base portion 12a of the sub-seal 12 than the contact portion between the first lip portion 12b and the cylinder head 7 so as not to interfere with the sealing function of the first lip portion 12b. ing. Therefore, even if the tension detection unit 20 is provided, the sub-seal 12 is in a state where the first lip portion 12b is in contact with the first bottom surface 8a and the second lip portion 12c is in contact with the outer peripheral surface 3a of the piston rod 3. Therefore, it is possible to reliably prevent the hydraulic oil that has flowed into the annular groove 8 from leaking to the outside.

As shown in FIG. 5, the tension force detecting unit 20 comprises a pair of electrodes 22, a pressure-sensitive conductive rubber 21 provided between the pair of electrodes 22, and a pair of electrodes 22 and a pressure-sensitive conductive rubber 21. It has an insulating material 23 that surrounds it.

The pressure-sensitive conductive rubber 21 is a rubber material such as silicon rubber having insulating properties mixed with conductive particles such as carbon and metal powder in a predetermined ratio. Therefore, when a force (pressure) as shown by an arrow A in FIG. 5 acts, the resistance value between the pair of electrodes 22 changes according to the magnitude of the force.

Therefore, by detecting the resistance value between the pair of electrodes 22 of the tension detection unit 20 arranged between the sub-seal 12 and the cylinder head 7, the magnitude of the pressure acting on the tension detection unit 20, that is, the magnitude of the pressure acting on the tension detection unit 20, that is, It is possible to grasp the tense force in the radial direction of the sub-seal 12. The tension of the sub-seal 12 detected by the tension detection unit 20 corresponds to the elastic restoring force generated when the second lip portion 12c of the sub-seal 12 is pressed against the outer peripheral surface 3a of the piston rod 3 and elastically deforms. To do.

As described above, the tension detecting unit 20 has an extremely simple structure of a pair of electrodes 22 and a pressure-sensitive conductive rubber 21, so that its molding is easy. Therefore, as shown in FIG. 3, it is possible to suppress an increase in manufacturing cost even when the sub-seal 12 is provided in a wide range along the outer peripheral surface.

Further, since the tension force detecting unit 20 is provided in an annular shape along the outer peripheral surface of the sub-seal 12, a value obtained by averaging the tension force in the radial direction of the sub-seal 12 over the entire circumference is obtained. Therefore, for example, when the posture of the hydraulic cylinder 1 changes and the direction in which the weight of the piston rod 3 acts changes, there are a portion where the tension force increases and a portion where the tension force decreases. An averaged tension is detected. The tension force detecting unit 20 formed in an annular shape in this way can detect a value in which the influence of a partial change in tension force due to an external factor such as a change in the posture of the hydraulic cylinder 1 is mitigated.

The deterioration determination unit 30 determines the deterioration state of the seal member 10 based on the resistance detection circuit 31 that detects the resistance value between the pair of electrodes 22 of the tension detection unit 20 and the resistance value detected by the resistance detection circuit 31. It has a determination unit 32 and a determination unit 32.

The determination unit 32 is a microcomputer, and is calculated by the calculation unit 33 and the calculation unit 33 that calculate the tense force in the radial direction of the subseal 12 based on the resistance value between the pair of electrodes 22 detected by the resistance detection circuit 31. A storage unit 34 that can store the tension force and a reference value of the tension force is stored, an auxiliary storage unit such as a ROM or RAM (not shown) that stores a program or the like used in the calculation unit 33, and an input (not shown). It has an output interface (I / O interface).

Further, the calculation unit 33 compares the calculated tension force of the sub-seal 12 with the reference value of the tension force stored in the storage unit 34, and determines the deterioration state of the seal member 10 based on the comparison result. ..

The calculation unit 33 is a so-called central processing unit (CPU), and the storage unit 34 is a rewritable non-volatile memory such as EEPROM. The deterioration determination unit 30 may be provided outside the hydraulic cylinder 1, or may be arranged inside the cylinder head 7 together with the tension detection unit 20.

Subsequently, with reference to FIG. 6, the deterioration determination of the seal member 10 by the seal state detection device 100 having the above configuration will be described.

Since the seal member 10 is usually formed of a rubber material, it gradually hardens due to deterioration over time, and the elastic restoring force, that is, the tense force, which is the force for pressing the lip portions 12b and 12c, gradually decreases. The seal state detection device 100 determines whether or not the seal member 10 is in a deteriorated state from such a change in the tense force.

First, in the seal state detection device 100, the state in which the sub-seal 12 is first assembled to the hydraulic cylinder 1, that is, the tense force of the sub-seal 12 at the time of shipment of the so-called hydraulic cylinder 1 is detected and stored in the storage unit 34 as an initial value. .. Specifically, the resistance value between the pair of electrodes 22 of the tension detection unit 20 is detected in the resistance detection circuit 31, and the calculation unit 33 calculates the tension in the radial direction of the subseal 12 based on the detected resistance value. Will be done. The tense force of the subseal 12 calculated by the calculation unit 33 in this way is stored in the storage unit 34 as an initial value. When the sub-seal 12 is replaced, the tense force of the sub-seal 12 is detected in the same manner and stored in the storage unit 34 as an initial value. In this case, the value stored in the storage unit 34 before the sub-seal 12 is replaced is erased.

After the initial value is stored in the storage unit 34, the seal state detection device 100 calculates the tense force of the sub-seal 12 at an arbitrary timing such as when the mechanical device provided with the hydraulic cylinder 1 is started or stopped. Then, at the same time as the calculation of the tension force, the calculation unit 33 compares the calculated tension force with the first reference value and the second reference value stored in the storage unit 34.

The calculation of the tension force of the sub-seal 12 may be always performed while the hydraulic cylinder 1 is operating, and the average value of the tension force calculated during a predetermined period is the first reference value and the second reference value. It may be used for comparison with the value. Further, since the deterioration of the seal member 10 progresses over a relatively long time, the calculation of the tense force of the sub-seal 12 may be performed every few weeks or months.

Further, when the inclination of the hydraulic cylinder 1 changes depending on the operating state of the mechanical device, the magnitude of the own weight of the piston rod 3 acting on the tension force detecting unit 20 changes, so that the tension of the subseal 12 calculated by the calculation unit 33 changes. The force is also affected by this and changes. Therefore, when the tense force of the sub-seal 12 is detected by the seal state detection device 100, it is preferable that the posture of the hydraulic cylinder 1 is in the same state every time.

The first reference value is set to a value corresponding to the tense force of the sub-seal 12 when the sub-seal 12 deteriorates, and the second reference value is a value larger than the first reference value and the initial value, and the rod side chamber 5 The pressure of the hydraulic oil inside is set to a value corresponding to the tense force of the sub-seal 12 when it directly acts on the sub-seal 12.

The first reference value may be a value set based on the initial value stored in the storage unit 34. For example, a value obtained by subtracting the amount of decrease in the tension force predicted when the sub-seal 12 deteriorates from the initial value, or a value at a predetermined ratio of the initial value, for example, a value of 60% of the initial value may be used as the first reference value. Good. Similarly, the second reference value may be a value set based on the initial value stored in the storage unit 34. For example, a value obtained by adding the amount of increase in the tense force predicted when the pressure of the hydraulic oil in the rod side chamber 5 directly acts on the sub-seal 12 to the initial value, or a value at a predetermined ratio of the initial value, for example, the initial value. A value of 200% may be used as the second reference value.

Since the deterioration of the seal member 10 progresses with the passage of time, the tense force of the sub-seal 12 calculated by the calculation unit 33 starts from the initial value with the passage of time, for example, as shown by the solid line in the graph of FIG. It gradually decreases and eventually falls below the first reference value. In this way, when the tense force of the sub-seal 12 calculated by the calculation unit 33 falls below the first reference value, the calculation unit 33 determines that the sub-seal 12 has deteriorated.

On the other hand, since the main seal 11 is located between the sub-seal 12 and the rod side chamber 5, the pressure of the hydraulic oil in the rod side chamber 5 does not normally act directly on the sub-seal 12. However, when the main seal 11 deteriorates and a leak occurs, the pressure of the hydraulic oil in the rod side chamber 5 directly acts on the sub seal 12.

When the pressure of the hydraulic oil in the rod side chamber 5 acts on the sub-seal 12, the pressure of the hydraulic oil acts as a force for pressing the first lip portion 12b and the second lip portion 12c against the cylinder head 7 and the piston rod 3, respectively. As a result, the tension of the sub-seal 12 increases.

Therefore, when the main seal 11 leaks, for example, as shown by the broken line in the graph of FIG. 6, the tense force of the sub-seal 12 calculated by the calculation unit 33 sharply increases, and the second reference value is set. It will exceed. Therefore, when the tense force of the sub-seal 12 calculated by the calculation unit 33 exceeds the second reference value, the calculation unit 33 determines that the main seal 11 has deteriorated.

When the calculation unit 33 determines that the main seal 11 or the sub seal 12 has deteriorated, the operator is notified that the seal member 10 has deteriorated through a display such as a warning lamp (not shown).

The resistance value between the pair of electrodes 22 detected by the resistance detection circuit 31 and the tense force of the subseal 12 calculated by the calculation unit 33 are for maintenance of the mechanical device arranged at a remote location via a communication unit (not shown). It may be sent to the server or the like. In this case, it is possible to grasp the deteriorated state of the seal member 10 at a remote location, and to instruct the replacement of the seal member 10 before the hydraulic oil leaks.

According to the above embodiment, the following effects are obtained.

In the seal state detection device 100, the presence or absence of deterioration of the seal member 10 is determined based on the tension force of the seal member 10 detected over time by the tension force detection unit 20. By constantly monitoring the tense force of the seal member 10 in this way, deterioration of the seal member 10 can be detected before the hydraulic oil leaks in the hydraulic cylinder 1.

Further, by preventing the hydraulic oil from leaking from the hydraulic cylinder 1, it is possible to avoid an unexpected situation such as a sudden stop of operation of the mechanical device in which the hydraulic cylinder 1 is used. Further, since the deteriorated state of the seal member 10 is automatically detected by the seal state detection device 100 incorporated in the hydraulic cylinder 1, the hydraulic cylinder 1 is disassembled and the deteriorated state of the seal member 10 is visually confirmed. By eliminating the need, the efficiency of inspection work can be improved.

Next, a modified example of the above embodiment will be described.

In the above embodiment, the case where the fluid pressure device is the hydraulic cylinder 1 has been described. Not limited to this, the seal state detection device 100 has a shaft that slides or rotates in the axial direction, and is used as a fluid pressure device for supplying and discharging a working fluid to a shock absorber, a hydraulic motor, a hydraulic pump, or the like. It may be used. The hydraulic fluid is not limited to hydraulic oil, and for example, water or other liquid may be used.

Further, in the above embodiment, the case where the seal member 10 is a U packing has been described. Not limited to this, the seal member 10 may be of any type as long as it is arranged between the piston rod 3 and the cylinder head 7 in a compressed state and can prevent leakage of hydraulic oil. It may be an O-ring or an oil seal.

Further, in the above embodiment, the seal member 10 has two seal members, a main seal 11 and a sub seal 12. Instead of this, the seal member 10 may be only the main seal 11 or may have three or more seal members.

Further, in the above embodiment, the seal state detection device 100 detects the tense force of the sub-seal 12 and determines the deterioration of the sub-seal 12. Instead, the seal state detection device 100 may detect the tense force of both the main seal 11 and the sub seal 12, determine the deterioration of these, or detect the tense force of only the main seal 11. At the same time, the deterioration of the main seal 11 may be determined.

Since the pressure of the hydraulic oil in the rod side chamber 5 acts directly on the main seal 11, the detected tense force of the main seal 11 greatly fluctuates according to the pressure of the hydraulic oil supplied to the rod side chamber 5. There is a risk. For this reason, it is necessary to take measures such as performing averaging processing and setting the timing of calculation to a timing with small fluctuation. For example, the tense force of the main seal 11 may be detected at the timing when the pressure of the hydraulic oil does not act on the rod side chamber 5 and the anti-rod side chamber 6 and the hydraulic cylinder 1 is in the stopped state. On the other hand, since the pressure of the hydraulic oil in the rod side chamber 5 does not directly act on the sub-seal 12, the tension force of the detected sub-seal 12 has a relatively small fluctuation and becomes a stable value. Therefore, it is possible to improve the deterioration determination accuracy by determining the deterioration of the seal member 10 based on the tense force of the sub-seal 12 as in the above embodiment.

Further, in the above embodiment, the calculation unit 33 notifies the operator and the like only when it is determined that the main seal 11 or the sub seal 12 has deteriorated. Instead of this, the initial value may be set to 0%, the first reference value may be set to 100%, and the detected tense force of the sub-seal 12 may be constantly displayed as the degree of deterioration of the seal member 10 by a percentage. In this case, it is preferable to encourage the operator or the like to replace the seal member 10 by changing the display color and the display method as it approaches 100%.

Further, in the above embodiment, the tension detecting unit 20 has a pair of electrodes 22 and a pressure-sensitive conductive rubber 21. The tension force detecting unit 20 is not limited to this, and any type of load sensor can be used as long as it can detect a radial force acting between the cylinder head 7 and the sub-seal 12. You may. For example, it may be a load sensor using a strain gauge or a piezoelectric element.

Further, in the above embodiment, the tension detection unit 20 is provided in an annular shape along the outer peripheral surface of the sub-seal 12. Instead of this, as shown in the first modification of FIG. 7, a plurality of tension force detecting units 20a to 20h may be provided along the outer peripheral surface of the sub-seal 12. In this case, it is possible to identify which part of the sub-seal 12 has deteriorated by grasping the tension force detected by each tension force detecting unit 20a to 20h.

Further, in the above embodiment, the tension detection unit 20 is provided in an annular shape along the outer peripheral surface of the sub-seal 12. Instead of this, as shown in the second modification of FIG. 8, the tension force detecting unit 20i may be provided only in a part along the outer peripheral surface of the sub-seal 12. In this case, by reducing the range in which the tension force detection unit 20i is provided and providing the tension force detection unit 20i only in the portion where deterioration is likely to occur, the seal state detection is performed as compared with the case where the tension force detection unit 20i is annular. The manufacturing cost of the device 100 can be reduced, and the deterioration determination accuracy can be improved.

Further, in the above embodiment, the tension detection unit 20 is provided separately from the sub-seal 12. Instead of this, as shown in the third modification of FIG. 9, the tension force detecting unit 20 may be integrally formed with the sub-seal 12. In this case, by assembling the sub-seal 12 to the hydraulic cylinder 1, the tension detection unit 20 is also assembled to the hydraulic cylinder 1, so that the efficiency of the assembling work can be improved.

Hereinafter, the configurations, actions, and effects of the embodiments of the present invention will be collectively described.

The seal state detection device 100 for detecting the seal state of the seal member 10 provided in a compressed state between the piston rod 3 and the cylinder head 7 that slidably supports the piston rod 3 is the outer peripheral surface of the seal member 10 and the cylinder. Based on the tension force detecting unit 20 provided between the inner peripheral surface of the head 7 and detecting the tension force of the seal member 10 in the radial direction, and the tension force of the seal member 10 detected by the tension force detection unit 20. A deterioration determination unit 30 for determining deterioration of the seal member 10 is provided.

In this configuration, the presence or absence of deterioration of the seal member 10 is determined based on the tension force of the seal member 10 detected over time by the tension force detection unit 20. By constantly monitoring the tense force of the seal member 10 in this way, it is possible to detect the deterioration of the seal member 10 before the hydraulic oil leaks in the hydraulic cylinder 1.

Further, in this configuration, the deteriorated state of the seal member 10 is automatically detected by the seal state detection device 100 incorporated in the hydraulic cylinder 1, so that the hydraulic cylinder 1 is disassembled and the seal member 10 is visually deteriorated. By eliminating the need to check the status, the efficiency of inspection work can be improved. Further, when the seal member 10 is replaced periodically, the seal member 10 which has not been deteriorated may also be replaced, but the seal state detection device 100 having the above configuration determines that the seal member 10 has deteriorated. Maintenance costs can be reduced by replacing the seal member 10 only in such cases. In this way, the seal member 10 is replaced at an appropriate time, and the hydraulic oil leakage of the hydraulic cylinder 1 is prevented in advance, so that the operation of the mechanical device in which the hydraulic cylinder 1 is used is unexpectedly stopped. The situation can be avoided.

Further, the tension force detecting unit 20 is provided in an annular shape along the outer peripheral surface of the seal member 10.

In this configuration, the tension detection unit 20 is provided in an annular shape along the outer peripheral surface of the seal member 10. Therefore, a value obtained by averaging the tense force in the radial direction of the seal member 10 over the entire circumference is obtained. That is, for example, when the direction in which the weight of the piston rod 3 acts changes due to a change in the posture of the hydraulic cylinder 1, there are a portion where the tension force increases and a portion where the tension force decreases, but the tension force detection unit 20 averages them. The increased tension is detected. In this way, the tension force detecting unit 20 can detect a value in which the influence of a partial change in tension force due to an external factor such as a change in the posture of the hydraulic cylinder 1 is mitigated. Then, in the seal state detection device 100, the deterioration of the seal member 10 is determined based on the average tension force detected in this way, so that the deterioration determination accuracy can be improved. Further, since there are few wires connected to the tension detection unit 20 and the structure is simple, assembling work such as wiring can be easily performed, and the manufacturing cost of the seal state detection device 100 can be reduced. Can be done.

Further, a plurality of tension force detecting units 20a to 20h are provided along the outer peripheral surface of the seal member 10.

In this configuration, a plurality of tension force detecting units 20a to 20h are provided along the outer peripheral surface of the seal member 10. Therefore, by grasping the tension force detected by each tension force detecting unit 20a to 20h, it is possible to identify in which part of the seal member 10 the deterioration has occurred.

Further, the tension force detecting unit 20i is partially provided along the outer peripheral surface of the seal member 10.

In this configuration, the tension detection unit 20i is provided only partially along the outer peripheral surface of the seal member 10. By reducing the range in which the tension force detection unit 20i is provided and providing the tension force detection unit 20i only in the portion where deterioration is likely to occur, the seal state detection is performed as compared with the case where the tension force detection unit 20i is annular. The manufacturing cost of the device 100 can be reduced, and the deterioration determination accuracy can be improved.

Further, the seal member 10 includes an annular base portion 12a, a first lip portion 12b extending axially from the base portion 12a and contacting the inner peripheral surface of the cylinder head 7, and a piston rod 3 extending axially from the base portion 12a. It has a second lip portion 12c in contact with the outer peripheral surface 3a, and the tension detecting portion 20 is arranged closer to the base portion 12a than the contact portion between the first lip portion 12b and the cylinder head 7.

In this configuration, the tension detection unit 20 is arranged closer to the base portion 12a than the portion where the first lip portion 12b and the cylinder head 7 come into contact with each other. In this way, the tension detection unit 20 is arranged so as not to interfere with the sealing function of the first lip unit 12b. Therefore, even if the tension detection unit 20 is provided, the sub-seal 12 is in a state where the first lip portion 12b is in contact with the first bottom surface 8a and the second lip portion 12c is in contact with the outer peripheral surface 3a of the piston rod 3. Therefore, it is possible to reliably prevent the hydraulic oil that has flowed into the annular groove 8 from leaking to the outside.

Further, the tension detection unit 20 has a pair of electrodes 22 and a pressure-sensitive conductive rubber 21 sandwiched between the pair of electrodes 22, and the resistance value between the pair of electrodes 22 is the seal member 10. It changes according to the tension.

In this configuration, the tension detecting unit 20 has a pair of electrodes 22 and a pressure-sensitive conductive rubber 21 sandwiched between the pair of electrodes 22. As described above, since the tension force detecting unit 20 has an extremely simple structure, its molding can be easily performed. Therefore, even when the sub-seal 12 is provided in an annular shape along the outer peripheral surface, it is possible to suppress an increase in the manufacturing cost of the seal state detection device 100 as compared with the case where the strain gauge, the piezoelectric element, or the like is arranged in an annular shape. Can be done.

Further, the tension detection unit 20 is integrally formed with the sub-seal 12.

In this configuration, the tension detection unit 20 is integrally formed with the sub-seal 12. Therefore, by assembling the sub-seal 12 to the hydraulic cylinder 1, the tension detection unit 20 can also be assembled to the hydraulic cylinder 1, so that the efficiency of the assembling work can be improved.

Further, the deterioration determination unit 30 determines that the seal member 10 has deteriorated when the tension force of the seal member 10 detected by the tension force detection unit 20 is smaller than the preset first reference value.

In this configuration, when the tension force of the seal member 10 detected by the tension force detection unit 20 is smaller than the preset first reference value, it is determined that the seal member 10 has deteriorated. By constantly monitoring the tense force of the seal member 10 in this way, deterioration of the seal member 10 can be detected before the hydraulic oil leaks in the hydraulic cylinder 1.

Further, the seal member 10 has a main seal 11 on which the pressure of hydraulic oil acts directly, and a sub-seal 12 arranged at a predetermined distance from the main seal 11 in the axial direction of the piston rod 3, and has a tense force. The detection unit 20 is arranged so as to detect the tense force of the sub-seal 12.

In this configuration, the tension detection unit 20 detects the tension of the sub-seal 12. Since the pressure of the hydraulic oil in the rod side chamber 5 does not directly act on the sub-seal 12, the tension force of the detected sub-seal 12 has a stable value with relatively little fluctuation. Therefore, by determining the deterioration of the seal member 10 based on the tense force of the sub-seal 12, the accuracy of determining the deterioration of the seal member 10 can be improved.

Further, the deterioration determination unit 30 determines that the sub-seal 12 has deteriorated when the tension of the sub-seal 12 detected by the tension detection unit 20 is smaller than the preset first reference value, and determines that the sub-seal 12 has deteriorated. If it is larger than the second reference value, it is determined that the main seal 11 has deteriorated.

In this configuration, when the tension force of the sub-seal 12 detected by the tension force detection unit 20 is smaller than the preset first reference value, it is determined that the sub-seal 12 has deteriorated, and it is larger than the second reference value. In that case, it is determined that the main seal 11 has deteriorated. By constantly monitoring the tense force of the sub-seal 12, it is possible to detect the deterioration of the seal member 10 before the hydraulic oil leaks in the hydraulic cylinder 1, and which of the main seal 11 and the sub-seal 12 can be used. It is possible to determine whether it has deteriorated.

Although the embodiments of the present invention have been described above, the above embodiments are only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configurations of the above embodiments. Absent.

100 ... Seal state detector, 1 ... Hydraulic cylinder (fluid pressure device), 3 ... Piston rod (shaft), 7 ... Cylinder head (housing), 8 ... Annular groove, 8a ... ... 1st bottom surface, 8b ... 2nd bottom surface, 10 ... Seal member, 11 ... Main seal, 12 ... Sub seal, 12a ... Base part, 12b ... 1st lip part, 12c ... 2nd lip part, 13 ... Dust seal, 20, 20a to 20i ... Tension force detection part, 21 ... Pressure-sensitive conductive rubber, 22 ... Pair of electrodes, 30 ... Deterioration judgment unit, 31 ... Resistance detection circuit, 32 ... Judgment unit, 33 ... Calculation unit, 34 ... Storage unit

Claims (8)

A seal state detection device that detects the seal state of a seal member provided in a compressed state between a shaft and a housing that slides and supports the shaft.
A tension force detecting unit provided between the outer peripheral surface of the seal member and the inner peripheral surface of the housing to detect the tension force of the seal member in the radial direction.
A deterioration determination unit for determining deterioration of the seal member based on the tension force of the seal member detected by the tension detection unit is provided .
The seal member has a main seal on which the pressure of the working fluid acts directly, and a sub-seal arranged at a predetermined distance from the main seal in the axial direction of the shaft.
The tension detection unit is arranged so as to detect only the tension of the sub-seal among the main seal and the sub-seal.
The deterioration determination unit is a seal state detection device that determines deterioration of the main seal and the sub-seal based on the tension of the sub-seal detected by the tension detection unit. A seal state detection device that detects the seal state of a seal member provided in a compressed state between a shaft and a housing that slides and supports the shaft.
A tension force detecting unit provided integrally with the seal member on the outer peripheral side of the seal member and detecting the tension force of the seal member in the radial direction.
A deterioration determination unit for determining deterioration of the seal member based on the tension force of the seal member detected by the tension detection unit is provided.
The seal member has a main seal on which the pressure of the working fluid acts directly, and a sub-seal arranged at a predetermined distance from the main seal in the axial direction of the shaft.
The tension detection unit is arranged so as to detect only the tension of the sub-seal among the main seal and the sub-seal.
The deterioration determination unit is a seal state detection device that determines deterioration of the main seal and the sub-seal based on the tension of the sub-seal detected by the tension detection unit. The seal state detecting device according to claim 1 or 2 , wherein the tension detecting unit is provided in an annular shape along the outer peripheral surface of the sealing member. The seal state detecting device according to claim 1 or 2 , wherein a plurality of the tension detecting units are provided along the outer peripheral surface of the sealing member. The seal state detecting device according to claim 1 or 2 , wherein the tension detecting unit is partially provided along the outer peripheral surface of the sealing member. The sealing member includes an annular base portion, a first lip portion extending axially from the base portion and contacting the inner peripheral surface of the housing, and a second lip portion extending axially from the base portion and contacting the outer peripheral surface of the shaft. With a lip part,
The seal state detection according to any one of claims 1 to 5 , wherein the tension detection unit is arranged closer to the base portion than the contact portion between the first lip portion and the housing. apparatus. The tension detecting unit has a pair of electrodes and a pressure-sensitive conductive rubber sandwiched between the pair of electrodes.
The seal state detecting device according to any one of claims 1 to 6 , wherein the resistance value between the pair of electrodes changes according to the tense force of the sealing member. The deterioration determination unit determines that the sub-seal has deteriorated when the tension of the sub-seal detected by the tension detection unit is smaller than a preset first reference value, and determines that the sub-seal has deteriorated. The seal state detecting device according to any one of claims 1 to 7, wherein if it is larger than the second reference value, it is determined that the main seal has deteriorated.

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