JP2018155492A - Fluid leakage detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect deterioration of a sealing function in a seal area in a fluid pressure device before fluid leaks to the outside.SOLUTION: In a main seal 13 for sealing a rod side chamber 5 to which the fluid pressure is applied, a fluid leakage detector 100 for detecting fluid leakage includes: a first load detecting unit 21 for detecting a first load acting on the main seal 13; a second load detecting unit 22 for detecting a second load acting on a sub seal 14 for sealing the rod side chamber 5 at a position outside the main seal 13 with respect to the rod side chamber 5; and a determination unit 32 for determining fluid leakage of the main seal 13 on the basis of the first load and the second load.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fluid leak detection device used in a fluid pressure device.

  A fluid pressure device having a shaft that slides or rotates in an axial direction usually includes a seal 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. Yes. Such a seal member may deteriorate in sealing performance due to deterioration with time or the like and cause fluid leakage.

  Patent Document 1 discloses a fluid leak detection device that detects whether a fluid leak has occurred in a fluid pressure device. In this fluid leak detection device, it is determined that a fluid leak has occurred when the amount of fluid per unit time that accumulates in a metering unit provided below the cylinder end exceeds a reference value.

Japanese Patent Laid-Open No. 06-207608

  However, in the fluid leak detection device described in Patent Document 1, the fluid leak is determined after the fluid leaks to the outside of the fluid pressure device. Thus, after the fluid leaks to the outside of the fluid pressure device, it becomes difficult to avoid malfunction of the fluid pressure device, and there is a risk that the operation of the mechanical device using the fluid pressure device may be suddenly stopped. is there.

  The present invention has been made in view of the above problems, and an object of the present invention is to detect a decrease in the sealing function in the sealing region before fluid leaks to the outside in the fluid pressure device.

  According to a first aspect of the present invention, there is provided a first load detection unit that detects a first load acting on a first seal portion that seals a sealed space to which a fluid pressure is applied, and an outer side of the first seal portion with respect to the sealed space. A second load detector for detecting a second load acting on a second seal portion that seals the sealed space at the position, a first load detected by the first load detector, and a first load detected by the second load detector. A determination unit that determines fluid leakage of the first seal unit based on two loads.

  In 1st invention, the 1st load which acts on the 1st seal part arrange | positioned in the position where the pressure of the fluid in a sealed space acts directly, and the 1st position located outside a 1st seal part with respect to a sealed space Whether or not fluid leakage has occurred in the first seal portion is determined based on the second load acting on the two seal portions. In this way, by monitoring whether or not the first seal portion arranged at a position where the pressure of the fluid in the sealed space directly acts can perform the sealing function, before the fluid leaks to the outside of the fluid pressure device. Furthermore, it is possible to detect a decrease in the sealing function in the sealing region.

  2nd invention WHEREIN: When the determination part has the difference of the 1st load detected by the 1st load detection part, and the 2nd load detected by the 2nd load detection part being less than the predetermined reference value It is determined that the fluid leaks from the first seal portion.

  In the second invention, when the difference between the first load detected by the first load detection unit and the second load detected by the second load detection unit falls below a predetermined reference value, the first seal It is determined that fluid leakage has occurred in the part. When fluid leakage occurs in the first seal portion, the fluid pressure acts on the second seal portion, and the magnitude of the second load increases to a value close to the first load. For this reason, it is possible to determine whether or not fluid leakage has occurred in the first seal portion by comparing a load difference, which is a difference between the first load and the second load, with a predetermined reference value.

  According to a third aspect of the present invention, the first seal portion and the second seal portion seal between the shaft and the housing that supports the slide of the shaft, and the shaft of the shaft on which the first load detection portion acts on the first seal portion. The load in the direction or radial direction is detected, and the second load detection unit detects a load acting in the same direction as the load detected by the first load detection unit and acting on the second seal portion. And

  In 3rd invention, the 1st load detection part and the 2nd load detection part have detected the load which acts on the same direction. As described above, the first load and the second load used for determining whether or not fluid leakage occurs in the first seal portion are loads acting in the same direction on the first seal portion and the second seal portion. It is. For this reason, it is possible to accurately determine whether or not fluid leakage has occurred in the first seal portion based on the change in the magnitude between the first load and the second load.

  According to a fourth aspect of the present invention, the housing has a first annular groove that accommodates the first seal portion and a second annular groove that accommodates the second seal portion, and the first load detection portion is the first seal portion. The second load detector is housed in the second annular groove together with the second seal portion.

  In 4th invention, a 1st load detection part and a 2nd load detection part are each accommodated in the 1st annular groove and 2nd annular groove provided in order to accommodate a 1st seal part and a 2nd seal part. The For this reason, the fluid leak detection device can be easily assembled to the fluid pressure device only by performing the processing for routing the wiring connecting each load detection unit and the determination unit on the housing.

  The fifth invention is characterized in that the first load detection part is formed integrally with the first seal part, and the second load detection part is formed integrally with the second seal part.

  In 5th invention, a 1st load detection part is formed integrally with a 1st seal part, and a 2nd load detection part is formed integrally with a 2nd seal part. For this reason, since the first load detection unit and the second load detection unit are also assembled to the fluid pressure device by assembling the first seal portion and the second seal portion to the fluid pressure device, fluid leakage detection is performed for the fluid pressure device. The efficiency of the work for assembling the device can be improved.

  In a sixth aspect of the present invention, the first load detector and the second load detector each have a pair of electrodes and a pressure-sensitive conductive rubber sandwiched between the pair of electrodes, and act on the first seal portion. The resistance value between the pair of electrodes of the first load detector changes according to the load to be applied, and the resistance value between the pair of electrodes of the second load detector changes according to the load acting on the second seal part. It is characterized by.

  In 6th invention, a 1st load detection part and a 2nd load detection part have a pair of electrodes and the pressure sensitive conductive rubber pinched | interposed between a pair of electrodes, respectively. Thus, since the 1st load detection part and the 2nd load detection part have simple composition, the formation is performed easily. Therefore, even if the first load detection unit and the second load detection unit are provided in a wide range, an increase in manufacturing cost of the fluid leak detection device can be suppressed.

  The seventh invention is characterized in that the first load detection portion and the second load detection portion are provided in an annular shape along the first seal portion and the second seal portion, respectively.

  In 7th invention, a 1st load detection part and a 2nd load detection part are each annularly provided along the 1st seal part and the 2nd seal part. For this reason, in the 1st load detection part and the 2nd load detection part, even if the pressure of the fluid which acts on each seal part varies in the peripheral direction, the average load which acts on each seal part is detected. As a result, in the fluid leak detection device, it is possible to accurately determine the deterioration of the seal function in the seal region.

  According to the present invention, it is possible to detect a decrease in the sealing function in the sealing region before fluid leaks to the outside in the fluid pressure device.

It is sectional drawing of the hydraulic cylinder in which the fluid leak detection apparatus which concerns on 1st Embodiment of this invention is used. It is an expanded sectional view showing the part in which the fluid leak detection device concerning a 1st embodiment of the present invention is provided. It is an expanded sectional view which expands and shows the seal member in which a load detection part is provided. It is sectional drawing of a load detection part. It is sectional drawing which follows the VV line of FIG. It is a graph which shows an example of the load detected by the load detection part. It is a graph for demonstrating determination of the fluid leak based on the load detected by the load detection part. It is sectional drawing which shows the 1st modification of a load detection part. It is sectional drawing which shows the 2nd modification of a load detection part. It is an expanded sectional view showing a part in which a fluid leak detection device concerning a 2nd embodiment of the present invention is provided. It is an expanded sectional view which expands and shows the seal member in which the load detection part of the fluid leak detection apparatus concerning 2nd Embodiment of this invention is provided.

  Hereinafter, a fluid leakage detection device according to an embodiment of the present invention will be described with reference to the drawings.

<First Embodiment>
With reference to FIGS. 1-7, the fluid leak detection apparatus 100 which concerns on 1st Embodiment of this invention, and a fluid pressure apparatus provided with the same are demonstrated.

  Below, the case where the fluid pressure device is the hydraulic cylinder 1 that drives the hydraulic oil as the 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 of the periphery of a portion where the fluid leak detection device 100 is provided. In addition, illustration of the fluid leak detection apparatus 100 is abbreviate | omitted in FIG.

  As shown in FIGS. 1 and 2, the hydraulic cylinder 1 includes a cylindrical 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). And a piston 4 that slides along the inner peripheral surface of the cylinder tube 2.

  The inside of the cylinder tube 2 is partitioned by the piston 4 into two hydraulic chambers of a rod side chamber 5 and an anti-rod side chamber 6 as a sealed space. The hydraulic cylinder 1 is expanded and contracted by operating hydraulic pressure guided to the rod side chamber 5 or the anti-rod side chamber 6 from a hydraulic source (not shown). The space between the inner periphery of the cylinder tube 2 and the outer periphery of the piston 4 is sealed by a seal member (not shown). Thereby, the communication between the rod side chamber 5 and the anti-rod side chamber 6 between the inner periphery of the cylinder tube 2 and the outer periphery of the piston 4 is blocked.

  The cylinder tube 2 is provided with a cylinder head 7 as a housing that closes the opening end of the cylinder tube 2 and supports the piston rod 3 slidably. 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, a bush 11, a seal region 12, and a dust seal 15 are provided on the inner periphery of the cylinder head 7 in this order from the rod side chamber 5 side to the outside.

  The bush 11 is disposed so as to be in sliding contact with the outer peripheral surface 3 a of the piston rod 3. For this reason, the piston rod 3 is slidably supported by the cylinder head 7 via the bush 11 and is movable along the axial direction of the cylinder tube 2.

  The seal region 12 is a region where the hydraulic oil in the rod side chamber 5 is prevented from leaking outside by a plurality of seal members. The seal region 12 has a main seal 13 as a first seal portion that is disposed on the bush 11 side and directly receives the pressure of hydraulic oil in the rod side chamber 5, and a predetermined distance from the main seal 13 in the axial direction of the piston rod 3. And a sub-seal 14 as a second seal portion disposed with a gap therebetween.

  The main seal 13 and the sub-seal 14 are U packings having a U-shaped cross section, and are compressed between the piston rod 3 and the cylinder head 7 so that the first annular groove 8 formed in the cylinder head 7 and It arrange | positions in the 2nd annular groove 9, respectively. The seal region 12 may be provided with a plurality of seal members in addition to the main seal 13 and the sub seal 14.

  The hydraulic oil in the rod side chamber 5 is normally prevented from leaking from the rod side chamber 5 by the main seal 13. However, when the sealing function of the main seal 13 is lowered due to deterioration of the main seal 13 and hydraulic oil leaks from the rod side chamber 5 through the gap between the main seal 13 and the piston rod 3, Thus, the hydraulic oil in the rod side chamber 5 is prevented from leaking to the outside by the sub seal 14 arranged at a position outside the main seal 13. That is, the sub seal 14 functions as a backup seal member, and the pressure of the hydraulic oil in the rod side chamber 5 does not act on the sub seal 14 as long as the main seal 13 functions normally.

  The dust seal 15 prevents dust from entering the cylinder tube 2 from the outside. Like the main seal 13 and the sub-seal 14, the dust seal 15 is compressed between the piston rod 3 and the cylinder head 7 in the cylinder. It is disposed in a groove formed in the head 7.

  In the hydraulic cylinder 1 having the above-described configuration, when the rod side chamber 5 communicates with a hydraulic pressure source and the anti-rod side chamber 6 communicates 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 discharged into the tank, the hydraulic cylinder 1 is contracted. On the other hand, when the anti-rod side chamber 6 communicates with the hydraulic pressure source and the rod side chamber 5 communicates 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 hydraulic cylinder 1 described above incorporates a fluid leakage detection device 100 that detects leakage of hydraulic oil that occurs when the sealing function in the sealing region 12 is lowered.

  Hereinafter, the fluid leak detection apparatus 100 will be described with reference to FIGS. 3 is an enlarged cross-sectional view showing a portion where load detectors 21 and 22 (described later) are provided, FIG. 4 is a cross-sectional view showing a cross section of the load detectors 21 and 22, and FIG. FIG. 5 is a cross-sectional view taken along line VV in FIG. 2, and is a cross-sectional view showing a cross section of the hydraulic cylinder 1 in a portion where the first load detection unit 21 is provided.

  As shown in FIG. 2, the fluid leak detection device 100 includes a first load detection unit 21 that is provided between the main seal 13 and the cylinder head 7 and detects a first load that acts on the main seal 13, and the sub seal 14. A second load detecting unit 22 provided between the cylinder head 7 and detecting a second load acting on the sub seal 14, and a first load detecting unit 21 and a second load detecting unit via a wiring indicated by a broken line in FIG. And a control unit 30 to which the unit 22 is connected.

  Here, the main seal 13 and the sub-seal 14 described above are disposed in the first annular groove 8 and the second annular groove 9 formed in the cylinder head 7, respectively, as shown in an enlarged view in FIG. The base portions 13a, 14a formed in the base, the first lip portions 13b, 14b extending in the axial direction from the base portions 13a, 14a and in contact with the bottom surfaces 8a, 9a of the annular grooves 8, 9 and the axial direction from the base portions 13a, 14a And second lip portions 13c and 14c that contact the outer peripheral surface 3a of the piston rod 3.

  As shown in FIG. 3, the first load detection unit 21 is disposed between the base portion 13 a of the main seal 13 and the side surface of the first annular groove 8. Thus, since the first load detection unit 21 is disposed so as to be sandwiched between the main seal 13 and the cylinder head 7 in the axial direction of the piston rod 3, the first load detection unit 21 includes the main seal 13 in the axial direction. The acting axial load will act.

  Similarly, as shown in FIG. 3, the second load detector 22 is disposed between the base portion 14 a of the sub seal 14 and the side surface of the second annular groove 9. Thus, since the second load detection unit 22 is disposed so as to be sandwiched between the sub seal 14 and the cylinder head 7 in the axial direction of the piston rod 3, the second load detection unit 22 acts on the sub seal 14. An axial load will act.

  As shown in FIG. 4, the first load detection unit 21 and the second load detection unit 22 include a pair of electrodes 25 arranged opposite to each other, and a pressure-sensitive conductive rubber 24 provided between the pair of electrodes 25. And an insulating material 26 surrounding the pair of electrodes 25 and the pressure-sensitive conductive rubber 24.

  The pressure-sensitive conductive rubber 24 is obtained by blending conductive particles such as carbon and metal powder in a predetermined ratio with a rubber material such as silicon rubber having insulating properties. Therefore, when a force (pressure) as indicated by an arrow A in FIG. 5 is applied, the resistance value between the pair of electrodes 25 changes according to the magnitude of the force.

  Therefore, the magnitude of the axial load acting on the main seal 13 by detecting the resistance value between the pair of electrodes 25 of the first load detection unit 21 arranged between the main seal 13 and the cylinder head 7. Can be grasped. Similarly, by detecting the resistance value between the pair of electrodes 25 of the second load detector 22 arranged between the sub seal 14 and the cylinder head 7, the magnitude of the axial load acting on the sub seal 14 can be determined. It becomes possible to grasp.

  Further, as shown in FIG. 5, the first load detection unit 21 is formed in an annular shape along the main seal 13, and is accommodated in the first annular groove 8 together with the main seal 13. Similarly to the first load detection unit 21, the second load detection unit 22 is formed in an annular shape along the sub seal 14, and is accommodated in the second annular groove 9 together with the sub seal 14.

  As described above, the first load detection unit 21 and the second load detection unit 22 are accommodated in the annular grooves 8 and 9 that are conventionally provided to accommodate the main seal 13 and the sub seal 14. For this reason, it is only necessary to form a slit or the like for routing the wiring connecting the first load detection unit 21 and the second load detection unit 22 and the control unit 30 in the cylinder head 7. Thus, the fluid leak detection device 100 can be easily assembled.

  Moreover, since the 1st load detection part 21 and the 2nd load detection part 22 have the very simple structure of a pair of electrode 25 and the pressure-sensitive conductive rubber 24 as mentioned above, the shaping | molding is easy. Therefore, as shown in FIG. 5, even when the first load detection unit 21 and the second load detection unit 22 are provided in a wide range along the seals 13 and 14, the fluid leak detection device 100 is manufactured. An increase in cost can be suppressed.

  In addition, since the first load detection unit 21 and the second load detection unit 22 are annularly provided along the seals 13 and 14, the first load detection unit 21 and the second load detection unit 22 include the seals 13 and 14. Even if the pressure of the hydraulic oil acting in the axial direction with respect to 14 varies in the circumferential direction, an average load acting on each of the seals 13 and 14 is detected. For example, if the direction in which the weight of the piston rod 3 acts due to a change in the posture of the hydraulic cylinder 1, the pressure acting on the seals 13 and 14 may partially increase or decrease partially. However, since the first load detection unit 21 and the second load detection unit 22 detect the average load acting on the seals 13 and 14, the influence of external factors such as a change in the posture of the hydraulic cylinder 1 is removed. The detected load can be detected.

  Next, the control unit 30 will be described.

  The control unit 30 is based on a resistance detection circuit 31 that detects a resistance value between the pair of electrodes 25 of the first load detection unit 21 and the second load detection unit 22, and a resistance value detected by the resistance detection circuit 31. And a determination unit 32 for determining fluid leakage in the seal region 12.

  The determination unit 32 is a microcomputer, and a first load that is a load in the axial direction of the main seal 13 and a load in the axial direction of the sub seal 14 based on the resistance value between the pair of electrodes 25 detected by the resistance detection circuit 31. A calculation unit 33 that calculates the second load, a calculation map that can store the load calculated by the calculation unit 33 and that indicates the correlation between the resistance value between the pair of electrodes 25 and the load, and determination of fluid leakage A storage unit 34 for storing reference values used in the storage unit, an auxiliary storage unit such as a ROM or a RAM (not shown) for storing programs used in the calculation unit 33, an input / output interface (I / O interface) (not shown), Have

  Further, the calculation unit 33 compares the calculated difference between the first load and the second load and the reference value stored in the storage unit 34, and based on the comparison result, the fluid leakage in the seal region 12 is compared. The presence or absence is determined.

  The calculation unit 33 is a so-called central processing unit (CPU), and the storage unit 34 is a rewritable nonvolatile memory such as an EEPROM. The control unit 30 may be provided outside the hydraulic cylinder 1 or may be disposed in the cylinder head 7 together with the first load detection unit 21 and the second load detection unit 22. In addition, the control unit 30 may be incorporated in a control unit that controls driving of a mechanical device in which the hydraulic cylinder 1 is provided.

  Next, with reference to FIG. 6 and FIG. 7, fluid leakage determination in the seal region 12 by the fluid leakage detection device 100 having the above configuration will be described. FIG. 6 is a graph showing temporal changes in the first load and the second load from the state in which the main seal 13 is functioning normally to the occurrence of hydraulic oil leakage in the main seal 13, and FIG. It is the graph which showed the time change of the difference of the 1st load shown by 2 and the 2nd load.

  Since the main seal 13 and the sub seal 14 provided in the seal region 12 are formed of a rubber material, the main seal 13 and the sub seal 14 are gradually cured due to deterioration with time. When the elastic restoring force, which is the force for pressing the lip portions 13b and 14b against the outer peripheral surface 3a of the piston rod 3 due to such deterioration with time, gradually decreases, the sealing function of the seals 13 and 14 decreases. Further, the sealing function of the seals 13 and 14 is partially reduced by contamination or the like contained in the hydraulic oil entering between the lip portions 13b and 14b and the outer peripheral surface 3a of the piston rod 3. In the fluid leak detection device 100, it is determined whether or not the hydraulic oil leaks in the main seal 13 with such a decrease in the sealing function.

  In the fluid leak detection device 100, the first load acting on the main seal 13 and the second load acting on the sub seal 14 are continuously detected while the mechanical device provided with the hydraulic cylinder 1 is operating. Specifically, the resistance value between the pair of electrodes 25 of the first load detection unit 21 is detected by the resistance detection circuit 31, and the first value in the axial direction of the main seal 13 is calculated by the calculation unit 33 based on the detected resistance value. The load is calculated. At the same time, the resistance value between the pair of electrodes 25 of the second load detection unit 22 is detected by the resistance detection circuit 31, and the second load in the axial direction of the sub seal 14 is calculated by the calculation unit 33 based on the detected resistance value. The

  Note that if the inclination of the hydraulic cylinder 1 changes depending on the operating state of the mechanical device, the influence of the weight of the piston rod 3 on the load detected by the first load detection unit 21 and the second load detection unit 22 may change. The detection of the first load and the second load is preferably performed when the posture of the hydraulic cylinder 1 is the same every time.

  Further, the calculation unit 33 compares the calculated difference between the first load and the second load with a predetermined reference value. When the difference between the first load and the second load falls below the reference value, it is determined that hydraulic fluid leakage has occurred in the main seal 13.

  Here, the axial load acting on the main seal 13 is mainly between the pressure of the hydraulic oil acting on the main seal 13 and between the main seal 13 and the piston rod 3 transmitted via the second lip portion 13c. Due to frictional force. The pressure of the hydraulic oil acting on the main seal 13 is the pressure of the hydraulic oil in the rod side chamber 5, and when the rod side chamber 5 is communicated with a hydraulic pressure source, the pressure is almost equal to the pressure of the hydraulic oil supplied from the hydraulic pressure source. It becomes. Since the load resulting from the pressure of the hydraulic oil supplied from the hydraulic source is very large compared to the frictional force between the main seal 13 and the piston rod 3, the load detected by the first load detector 21 is The load is caused by the pressure of the hydraulic oil acting on the main seal 13.

  Further, the axial load acting on the sub seal 14 is also transmitted mainly through the pressure of the hydraulic oil acting on the sub seal 14 and the second lip portion 14c, similarly to the axial load acting on the main seal 13. This is due to the frictional force between the sub seal 14 and the piston rod 3. However, if the seal function of the main seal 13 is in a normal state, the hydraulic oil in the rod side chamber 5 does not reach the sub seal 14, and therefore the pressure of the hydraulic oil acting on the sub seal 14 causes the hydraulic cylinder 1 to operate. Regardless, it is almost zero. For this reason, when the main seal 13 is normal, the load detected by the second load detector 22 is substantially a frictional force between the sub seal 14 and the piston rod 3. That is, if the seal function of the main seal 13 is in a normal state, the load detected by the second load detection unit 22 is a very small value compared to the load detected by the first load detection unit 21.

  Therefore, in FIG. 6, since the detection of each load is started, that is, after the main seal 13 and the sub seal 14 are first assembled, or after the main seal 13 and the sub seal 14 are replaced, for a while. When the sealing function of the main seal 13 is in a normal state, the second load is a relatively small value compared to the first load. In other words, the load difference, which is the difference between the first load and the second load, is a value larger than the reference value as shown in FIG.

  The pressure of the hydraulic oil acting on the main seal 13 is approximately equal to the pressure of the hydraulic oil supplied from the hydraulic source when the rod side chamber 5 is communicated with the hydraulic source, while the rod side chamber 5 is in the tank. When communicated, the pressure is close to the atmospheric pressure that is the pressure of the tank. For this reason, the load detected by the first load detection unit 21 varies greatly according to the operation of the hydraulic cylinder 1. For this reason, when comparing the first load and the second load, it is preferable to use the average value, maximum value, and effective value of each load in consideration of pressure fluctuations due to switching of the operation direction of the hydraulic cylinder 1.

  On the other hand, when the sealing function of the main seal 13 is deteriorated due to deterioration or the like and the hydraulic oil leaks from the gap between the main seal 13 and the piston rod 3, the hydraulic oil pressure in the rod side chamber 5 acts on the sub seal 14. It becomes a state. That is, when the sealing function of the main seal 13 is deteriorated, the sub-seal 14 is subjected to a pressure approximately equal to the pressure of the hydraulic oil acting on the main seal 13 and is detected by the second load detection unit 22. The load has the same magnitude as the load detected by the first load detector 21.

  For this reason, when a considerable time has elapsed since the detection of each load in FIG. 6 and the sealing function of the main seal 13 gradually decreases due to deterioration or the like, the hydraulic oil leaks in the main seal 13, The magnitude of the second load increases to a value close to the first load, and the load difference that is the difference between the first load and the second load is a value smaller than the reference value as shown in FIG.

  The reference value to be compared with the load difference only needs to be set to such a magnitude that it is determined that it is clear that the pressure of the hydraulic oil in the rod side chamber 5 acts on the sub seal 14. For example, it is set based on the initial value of the first load and the initial value of the second load detected at the time when detection of each load is started. Specifically, it is set to a half value of the initial load difference, which is the difference between the initial value of the first load and the initial value of the second load.

  As described above, when the difference between the first load and the second load is less than the reference value and the operation unit 33 determines that hydraulic oil leakage has occurred in the main seal 13, the operator is notified via a warning lamp or the like (not shown). It is notified that the sealing function is deteriorated in the sealing region 12.

  Further, the resistance value between the pair of electrodes 25 of the first load detection unit 21 and the second load detection unit 22 detected by the resistance detection circuit 31 and the first load and the second load calculated by the calculation unit 33 are shown in the figure. It may be wirelessly transmitted to a machine maintenance server or the like disposed in a remote place via a communication unit that does not. In this case, it is possible to grasp the presence or absence of hydraulic fluid leakage in the seal region 12 at a remote location, and instruct the replacement of the main seal 13 and the sub seal 14 before the hydraulic fluid leaks outside the hydraulic cylinder 1. Can do.

  According to the above 1st Embodiment, there exists an effect shown below.

  In the fluid leak detection device 100, the first load acting on the main seal 13 disposed at a position where the hydraulic oil pressure directly acts and the sub seal 14 disposed away from the main seal 13 in the axial direction of the piston rod 3. Based on the acting second load, it is determined whether or not hydraulic fluid has leaked in the main seal 13. Thus, by monitoring whether or not the main seal 13 disposed at a position where the hydraulic oil pressure directly acts can exhibit the sealing function, the hydraulic oil 1 is deteriorated before leaking to the outside of the hydraulic cylinder 1. Thus, it can be detected that the sealing function of the sealing region 12 is deteriorated.

  Further, since the hydraulic oil leakage of the hydraulic cylinder 1 is prevented in advance, it is possible to avoid an unexpected situation such as a sudden operation stop of the mechanical device in which the hydraulic cylinder 1 is used. Further, since hydraulic fluid leakage in the seal region 12 is automatically detected by the fluid leak detection device 100 incorporated in the hydraulic cylinder 1, the hydraulic cylinder 1 is disassembled and the hydraulic fluid leakage in the seal region 12 is visually observed. Since it is not necessary to check the presence or absence, the efficiency of the inspection work can be improved.

  Next, a modification of the first embodiment will be described.

  In the first embodiment, the case where the fluid pressure device is the hydraulic cylinder 1 has been described. Not limited to this, the fluid leak detection device 100 is used as a fluid pressure device that has a shaft that slides or rotates in the axial direction and that supplies and discharges working fluid, such as a shock absorber, a hydraulic motor, and a hydraulic pump. May be used. The working fluid is not limited to working oil, and for example, water, other liquids, gas, or the like may be used.

  Moreover, in the said 1st Embodiment, the case where the main seal 13 and the sub seal | sticker 14 were U packing was demonstrated. Not limited to this, the main seal 13 and the sub seal 14 may be of any type as long as the load in the axial direction is changed by the action of the hydraulic oil pressure in the rod side chamber 5. Or an oil seal.

  Moreover, in the said 1st Embodiment, in the calculating part 33, each load is calculated from the resistance value between a pair of electrodes 25, and the difference of each calculated load is compared with a reference value. Instead of this, the difference between the resistance value between the pair of electrodes 25 of the first load detection unit 21 and the resistance value between the pair of electrodes 25 of the second load detection unit 22 is calculated as a reference value without calculating each load. May be compared.

  In the first embodiment, the operator is notified only when the calculation unit 33 determines that hydraulic oil leakage has occurred in the main seal 13. Instead, the initial value of the load difference is set to 0%, the reference value is set to 100%, and the detected load difference between the first load and the second load is always displayed as a percentage of the seal function deterioration of the seal region 12 as a percentage. May be. In this case, it is preferable to prompt the operator or the like to replace the main seal 13 and the sub seal 14 by changing the display color and the display method as it approaches 100%.

  Further, in the first embodiment, by comparing the load difference between the first load and the second load with the reference value, it is determined whether or not hydraulic oil leakage has occurred in the main seal 13, that is, the sub seal 14 has a rod side chamber. It is determined whether or not the pressure of the hydraulic oil in 5 has reached a state of action. As described above, when hydraulic fluid leakage occurs in the main seal 13, the second load acting on the sub seal 14 varies greatly according to the operation of the hydraulic cylinder 1, as with the first load acting on the main seal 13. On the other hand, when no hydraulic oil leakage occurs in the main seal 13, the second load acting on the sub seal 14 hardly fluctuates. From this, when the magnitude of the peak peak value of the second load approaches the peak peak value of the first load, that is, the difference between the peak peak value of the first load and the peak peak value of the second load is a predetermined value. When the value is below the reference value, it may be determined that hydraulic fluid leakage has occurred in the main seal 13.

  In the first embodiment, the first load detection unit 21 and the second load detection unit 22 have a pair of electrodes 25 and a pressure-sensitive conductive rubber 24. The first load detection unit 21 and the second load detection unit 22 are not limited to this, as long as they can detect the axial force acting between the cylinder head 7 and the seals 13 and 14. Any type of load sensor may be used. For example, a load sensor using a strain gauge or a piezoelectric element may be used.

  In the first embodiment, the first load detector 21 and the second load detector 22 are provided separately from the seals 13 and 14. Instead of this, as shown in the first modification of FIG. 8, the first load detector 21 and the second load detector 22 may be formed integrally with the seals 13 and 14. In this case, since the first load detector 21 and the second load detector 22 are also assembled to the hydraulic cylinder 1 simply by assembling the seals 13 and 14 to the hydraulic cylinder 1, the efficiency of the assembling work can be improved.

  In the first embodiment, the first load detection unit 21 is provided in an annular shape along the main seal 13. Instead of this, as shown in the second modified example of FIG. 9, a plurality of first load detectors 21 a to 21 d may be provided along the main seal 13. In this case, in order to avoid the sealing force of the main seal 13 from becoming uneven in the circumferential direction, the first load detectors 21 a to 21 d are arranged at equiangular intervals with respect to the center of the piston rod 3. Is preferred. The same applies to the second load detector 22.

  In the first embodiment, the first load detection unit 21 is provided in an annular shape along the main seal 13. Instead, a configuration in which the first load detection unit is provided in part along the main seal 13 may be employed. In this case, in order to prevent the sealing force of the main seal 13 from becoming uneven in the circumferential direction, the main seal is located at a position that is symmetrical with respect to the position where the first load detector is provided with the center of the piston rod 3 interposed therebetween. It is preferable to provide a support surface for supporting 13 in the axial direction. The same applies to the second load detector 22.

  In the first embodiment, the first load acting on the main seal 13 and the second load acting on the sub seal 14 are continuously detected while the mechanical device provided with the hydraulic cylinder 1 is operating. The Since the deterioration of the main seal 13 and the sub-seal 14 proceeds over a relatively long time, when detecting a decrease in the sealing function due to the deterioration, the detection of the first load and the second load may take several weeks. It may be done every few months.

  While the mechanical device provided with the hydraulic cylinder 1 is in operation, the first load and the second load are always detected, and the presence or absence of hydraulic oil leakage in the main seal 13 is determined, so that the lip portion 13b It is also possible to detect a hydraulic oil leak that occurs suddenly when contamination or the like enters between the outer peripheral surface 3a of the piston rod 3 and the like.

Second Embodiment
Next, with reference to FIG.10 and FIG.11, the fluid leak detection apparatus 200 which concerns on 2nd Embodiment of this invention is demonstrated. Below, it demonstrates centering on a different point from 1st Embodiment, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment, and description is abbreviate | omitted.

  The basic configuration of the fluid leak detection apparatus 200 is the same as that of the fluid leak detection apparatus 100 according to the first embodiment. The fluid leak detection apparatus 200 is different from the fluid leak detection apparatus 100 in that the first load detection unit 121 and the second load detection unit 122 are arranged on the radially outer side of the seals 13 and 14.

  As shown in FIG. 10, the fluid leak detection device 200 includes a first load detection unit 121 that is provided between the main seal 13 and the cylinder head 7 and detects a first load that acts on the main seal 13, and the sub seal 14. A second load detection unit 122 that is provided between the cylinder head 7 and detects a second load acting on the sub seal 14, and a first load detection unit 121 and a second load detection via a wiring indicated by a broken line in FIG. 10. And a control unit 30 to which the unit 122 is connected.

  Here, as in the first embodiment, the main seal 13 and the sub-seal 14 described above are, as shown in an enlarged view in FIG. 11, the first annular groove 8 and the second annular groove 9 formed in the cylinder head 7. And base portions 13a, 14a formed in an annular shape, and first lip portions 13b, 14b extending in the axial direction from the base portions 13a, 14a and in contact with the bottom surfaces 8a, 9a of the annular grooves 8, 9; And second lip portions 13c and 14c extending in the axial direction from the base portions 13a and 14a and in contact with the outer peripheral surface 3a of the piston rod 3.

  The first annular groove 8 and the second annular groove 9 are deeper than the bottom surfaces 8a and 9a, and are formed on the base portions 13a and 14a side of the seals 13 and 14 continuously to the bottom surfaces 8a and 9a. It has the 2nd bottom face 8b, 9b. The first load detection unit 121 and the second load detection unit 122 are both formed in an annular shape, and are disposed between the second bottom surfaces 8b and 9b and the portions of the seals 13 and 14 near the base portions 13a and 14a. The

  As described above, the first load detector 121 and the second load detector 122 are contact portions between the first lip portions 13b and 14b and the cylinder head 7 so as not to hinder the sealing function of the first lip portions 13b and 14b. Further, the seals 13 and 14 are disposed closer to the base portions 13a and 14a. For this reason, even if the 1st load detection part 121 and the 2nd load detection part 122 are provided, each seal | sticker 13 and 14 contact | connects the bottom face 8a and 9a, and the 2nd lip part 13c 14c is in contact with the outer peripheral surface 3a of the piston rod 3, so that the hydraulic oil flowing into the annular grooves 8 and 9 can be reliably prevented from leaking outside.

  Further, since the first load detection unit 121 is disposed so as to be sandwiched between the main seal 13 and the cylinder head 7 in the radial direction of the piston rod 3, the first load detection unit 121 acts on the main seal 13. A tension force, which is a radial load, is applied. The tightening force of the main seal 13 detected by the first load detection unit 121 is an elastic restoration that occurs when the second lip portion 13c of the main seal 13 is pressed against the outer peripheral surface 3a of the piston rod 3 and elastically deforms. This corresponds to the resultant force of the force and the pressing force by which the second lip portion 13 c is pressed against the outer peripheral surface 3 a of the piston rod 3 by the hydraulic pressure of the hydraulic oil flowing into the first annular groove 8.

  Similarly, since the second load detector 122 is disposed so as to be sandwiched between the sub seal 14 and the cylinder head 7 in the radial direction of the piston rod 3, the second load detector 122 has a diameter acting on the sub seal 14. A tension force, which is a load in the direction, acts. The tightening force of the sub seal 14 detected by the second load detector 122 is an elastic restoring force generated by the second lip portion 14c of the sub seal 14 being pressed against the outer peripheral surface 3a of the piston rod 3 and elastically deforming. This corresponds to the resultant force of the pressing force by which the second lip portion 14 c is pressed against the outer peripheral surface 3 a of the piston rod 3 by the hydraulic pressure of the hydraulic oil flowing into the second annular groove 9.

  As in the first embodiment, the first load detection unit 121 and the second load detection unit 122 are a pair of electrodes 25 arranged to face each other, and a pressure-sensitive conductive rubber provided between the pair of electrodes 25. 24 and an insulating material 26 surrounding the pair of electrodes 25 and the pressure-sensitive conductive rubber 24.

  Therefore, the magnitude of the radial load acting on the main seal 13 by detecting the resistance value between the pair of electrodes 25 of the first load detection unit 21 disposed between the main seal 13 and the cylinder head 7. Can be grasped. Similarly, by detecting the resistance value between the pair of electrodes 25 of the second load detection unit 22 disposed between the sub seal 14 and the cylinder head 7, the magnitude of the radial load acting on the sub seal 14 can be reduced. It becomes possible to grasp.

  Since the structure of the control part 30 is the same as that of the said 1st Embodiment, the description is abbreviate | omitted.

  Next, with reference to FIG. 6 and FIG. 7, the fluid leakage determination in the seal region 12 by the fluid leakage detection device 200 having the above configuration will be described.

  In the fluid leak detection device 200, the first load acting on the main seal 13 and the second load acting on the sub seal 14 are detected continuously while the mechanical device provided with the hydraulic cylinder 1 is operating. Specifically, the resistance detection circuit 31 detects the resistance value between the pair of electrodes 25 of the first load detection unit 121, and the calculation unit 33 based on the detected resistance value in the first axial direction of the main seal 13. The load is calculated. At the same time, the resistance detection circuit 31 detects the resistance value between the pair of electrodes 25 of the second load detection unit 122, and the calculation unit 33 calculates the second load in the axial direction of the sub seal 14 based on the detected resistance value. The

  Further, the calculation unit 33 compares the calculated difference between the first load and the second load with a predetermined reference value. When the difference between the first load and the second load falls below the reference value, it is determined that hydraulic fluid leakage has occurred in the main seal 13.

  Here, the radial load acting on the main seal 13 is elastically restored as described above when the second lip portion 13c of the main seal 13 is pressed against the outer peripheral surface 3a of the piston rod 3 and elastically deforms. This corresponds to the resultant force of the force and the pressing force by which the second lip portion 13 c is pressed against the outer peripheral surface 3 a of the piston rod 3 by the hydraulic pressure of the hydraulic oil flowing into the first annular groove 8. The pressure of the hydraulic oil flowing into the first annular groove 8 is the pressure of the hydraulic oil in the rod side chamber 5. When the rod side chamber 5 is communicated with the hydraulic pressure source, the pressure of the hydraulic oil supplied from the hydraulic pressure source is increased. It becomes almost equal size. The pressing force with which the hydraulic oil supplied from the hydraulic source presses the second lip portion 13c against the outer peripheral surface 3a of the piston rod 3 is very large compared to the elastic restoring force, and is detected by the first load detection unit 21. The load to be applied is almost a pressing force due to the hydraulic oil flowing into the first annular groove 8.

  Similarly to the radial load acting on the main seal 13, the radial load acting on the sub seal 14 is also elastically deformed by pressing the second lip portion 14 c of the sub seal 14 against the outer peripheral surface 3 a of the piston rod 3. This corresponds to the resultant force of the elastic restoring force generated by the pressing and the pressing force by which the second lip portion 14c is pressed against the outer peripheral surface 3a of the piston rod 3 by the hydraulic pressure of the hydraulic oil flowing into the second annular groove 9. However, if the seal function of the main seal 13 is in a normal state, the hydraulic oil in the rod side chamber 5 does not reach the second annular groove 9, so that the hydraulic oil moves the second lip portion 14 c to the piston rod 3. The pressing force to be pressed against the outer peripheral surface 3a is substantially zero regardless of the operation of the hydraulic cylinder 1. For this reason, when the main seal 13 is normal, the load detected by the second load detector 122 is substantially the elastic restoring force of the second lip portion 14c. That is, if the seal function of the main seal 13 is in a normal state, the load detected by the second load detection unit 122 is a very small value compared to the load detected by the first load detection unit 121.

  Therefore, as in the first embodiment, in FIG. 6, the detection of each load is started, that is, after the main seal 13 and the sub seal 14 are first assembled, or the main seal 13 and the sub seal 14 are For a while after the replacement, the second load becomes a relatively small value compared to the first load because the sealing function of the main seal 13 is in a normal state. In other words, the load difference which is the difference between the first load and the second load is a value larger than the reference value as shown in FIG. When comparing the first load and the second load, as in the first embodiment, taking into account pressure fluctuations due to switching of the operation direction of the hydraulic cylinder 1, an average value or maximum value of each load, The effective value is preferably used.

  On the other hand, when the sealing function of the main seal 13 is reduced and hydraulic oil leaks from the gap between the main seal 13 and the piston rod 3, the pressure of the hydraulic oil in the rod side chamber 5 acts on the sub seal 14. . That is, when the sealing function of the main seal 13 is lowered, the hydraulic oil having the same pressure as the hydraulic oil flowing into the first annular groove 8 flows into the second annular groove 9. For this reason, the load detected by the second load detection unit 122 has the same magnitude as the load detected by the first load detection unit 121.

  For this reason, as in the first embodiment, when a considerable time has elapsed since the detection of each load in FIG. 6 and the sealing function of the main seal 13 gradually decreases due to deterioration or the like, the main seal 13 As the hydraulic oil leaks, the magnitude of the second load increases to a value close to the first load, and the load difference that is the difference between the first load and the second load is as shown in FIG. The value is smaller than the reference value.

  As described above, when the difference between the first load and the second load is less than the reference value and the arithmetic unit 33 determines that hydraulic oil leakage has occurred in the main seal 13, it is not illustrated as in the first embodiment. The operator is notified that the sealing function is deteriorated in the seal region 12 through a display such as a warning lamp.

  According to the above 2nd Embodiment, there exists an effect shown below.

  In the fluid leak detection device 200, the first load in the radial direction acting on the main seal 13 disposed at a position where the hydraulic oil pressure directly acts, and the axial direction of the piston rod 3 away from the main seal 13 are disposed. Based on the second radial load acting on the sub seal 14, it is determined whether or not hydraulic fluid has leaked in the main seal 13. Thus, by monitoring whether or not the main seal 13 disposed at a position where the hydraulic oil pressure directly acts can exhibit the sealing function, the hydraulic oil 1 is deteriorated before leaking to the outside of the hydraulic cylinder 1. Thus, it can be detected that the sealing function of the sealing region 12 is deteriorated.

  Hereinafter, the configuration, operation, and effect of the embodiment of the present invention will be described together.

  Fluid leakage detection devices 100 and 200 for detecting fluid leakage in the main seal 13 that seals the rod-side chamber 5 to which hydraulic oil pressure is applied include a first load detection unit 21 that detects a first load acting on the main seal 13. 121, second load detection units 22 and 122 for detecting a second load acting on the sub seal 14 that seals the rod side chamber 5 at a position outside the main seal 13 with respect to the rod side chamber 5, and a first load detection unit And a determination unit 32 that determines fluid leakage of the main seal 13 based on the first load detected by the first load detection unit 121 and the second load detected by the second load detection unit 22.

  In this configuration, the first load acting on the main seal 13 disposed at a position where the hydraulic oil pressure in the rod side chamber 5 directly acts, and the sub seal disposed away from the main seal 13 in the axial direction of the piston rod 3. 14 is determined based on the second load acting on the main seal 13. Thus, by monitoring whether or not the main seal 13 disposed at a position where the hydraulic oil pressure directly acts can exhibit the sealing function, the hydraulic oil 1 is deteriorated before leaking to the outside of the hydraulic cylinder 1. Thus, it can be detected that the sealing function of the sealing region 12 is deteriorated. As a result, the hydraulic oil leakage of the hydraulic cylinder 1 is prevented in advance, so that it is possible to avoid an unexpected situation such as a sudden operation stop of the mechanical device in which the hydraulic cylinder 1 is used.

  Further, in this configuration, since hydraulic fluid leakage in the seal region 12 is automatically detected by the fluid leak detection device 100 incorporated in the hydraulic cylinder 1, the hydraulic cylinder 1 is disassembled and visually observed in the seal region 12. By eliminating the need to check for hydraulic fluid leakage, the efficiency of inspection work can be improved. In addition, when the main seal 13 and the sub seal 14 provided in the seal region 12 are periodically replaced, the seal member that has not yet deteriorated is also replaced. Maintenance cost can be reduced by exchanging the main seal 13 and the sub seal 14 only when it is determined that the seal function of the region 12 is deteriorated. Thus, by exchanging the main seal 13 and the sub seal 14 at an appropriate time, it is possible to avoid an unexpected situation such as a sudden stoppage of the operation of the mechanical device using the hydraulic cylinder 1.

  In addition, the determination unit 32 determines that a difference between the first load detected by the first load detection units 21 and 121 and the second load detected by the second load detection units 22 and 122 is a predetermined reference value. If it falls below, it is determined that the main seal 13 is leaking fluid.

  In this configuration, when the difference between the first load detected by the first load detectors 21 and 121 and the second load detected by the second load detectors 22 and 122 is lower than a predetermined reference value. It is determined that fluid leakage has occurred in the main seal 13. When the sealing function of the main seal 13 is deteriorated due to deterioration or the like and the hydraulic oil leaks in the main seal 13, the hydraulic oil pressure is applied to the sub seal 14, and the magnitude of the second load is equal to the first load. Rise to a close value. Therefore, by comparing the load difference, which is the difference between the first load and the second load, with a predetermined reference value, whether or not hydraulic fluid leaks in the main seal 13, that is, the seal in the seal region 12. It is possible to accurately determine whether or not the function is deteriorated.

  The main seal 13 and the sub-seal 14 seal between the piston rod 3 and the cylinder head 7 that slide-supports the piston rod 3, and the first load detectors 21, 121 are piston rods that act on the main seal 13. 3, the load in the axial direction or the radial direction is detected, and the second load detectors 22 and 122 are loads in the same direction as the loads detected by the first load detectors 21 and 121 and act on the sub seal 14. Detect load.

  In this configuration, the first load detectors 21 and 121 and the second load detectors 22 and 122 detect loads acting in the same direction. As described above, the first load and the second load used for determining whether or not the hydraulic oil leaks in the main seal 13 are loads that act on the main seal 13 and the sub seal 14 in the same direction. . For this reason, it is possible to more accurately determine whether or not hydraulic fluid has leaked in the main seal 13 based on the change in magnitude between the first load and the second load.

  The cylinder head 7 has a first annular groove 8 that accommodates the main seal 13 and a second annular groove 9 that accommodates the sub-seal 14, and the first load detectors 21 and 121 together with the main seal 13 Housed in the first annular groove 8, the second load detectors 22 and 122 are housed in the second annular groove 9 together with the sub seal 14.

  In this configuration, the first load detectors 21 and 121 and the second load detectors 22 and 122 are the first annular groove 8 and the second annular groove that are conventionally provided to accommodate the main seal 13 and the sub seal 14. 9 respectively. For this reason, only by forming a slit or the like in the cylinder head 7 for wiring the wiring connecting the first load detection units 21 and 121 and the second load detection units 22 and 122 and the control unit 30, the hydraulic pressure can be increased. The fluid leak detection device 100 can be easily assembled to the cylinder 1.

  The first load detectors 21 and 121 are formed integrally with the main seal 13, and the second load detectors 22 and 122 are formed integrally with the sub seal 14.

  In this configuration, the first load detectors 21 and 121 are formed integrally with the main seal 13, and the second load detectors 22 and 122 are formed integrally with the sub seal 14. For this reason, the first load detectors 21 and 121 and the second load detectors 22 and 122 are also assembled to the hydraulic cylinder 1 by assembling the main seal 13 and the sub seal 14 to the hydraulic cylinder 1. The efficiency of the work of assembling the fluid leak detection devices 100 and 200 can be improved.

  The first load detectors 21 and 121 and the second load detectors 22 and 122 each have a pair of electrodes 25 and a pressure-sensitive conductive rubber 24 sandwiched between the pair of electrodes 25. The resistance value between the pair of electrodes 25 of the first load detectors 21 and 121 changes according to the load acting on the seal 13, and the pair of second load detectors 22 and 122 depends on the load acting on the sub seal 14. The resistance value between the electrodes 25 changes.

  In this configuration, the first load detectors 21 and 121 and the second load detectors 22 and 122 each have a pair of electrodes 25 and a pressure-sensitive conductive rubber 24 sandwiched between the pair of electrodes 25. Thus, since the 1st load detection parts 21 and 121 and the 2nd load detection parts 22 and 122 have a very simple composition, the formation is performed easily. Therefore, even when the first load detection units 21 and 121 and the second load detection units 22 and 122 are provided in a wide range along the main seal 13 and the sub seal 14, a strain gauge, a piezoelectric element, and the like are arranged in a wide range. Compared with the case where it did, the raise of the manufacturing cost of the fluid leak detection apparatus 100,200 can be suppressed.

  The first load detectors 21 and 121 and the second load detectors 22 and 122 are provided in an annular shape along the main seal 13 and the sub seal 14, respectively.

  In this configuration, the first load detectors 21 and 121 and the second load detectors 22 and 122 are provided annularly along the main seal 13 and the sub seal 14, respectively. For this reason, in the 1st load detection parts 21 and 121 and the 2nd load detection parts 22 and 122, even if the pressure of the hydraulic fluid which acts on each seal 13 and 14 varies in the peripheral direction, it acts on each seal 13 and 14. An average load is detected. For example, if the direction in which the weight of the piston rod 3 acts due to a change in the posture of the hydraulic cylinder 1, the pressure acting on the seals 13 and 14 may partially increase or decrease partially. However, since the first load detectors 21 and 121 and the second load detectors 22 and 122 detect average loads acting on the seals 13 and 14, external factors such as changes in the posture of the hydraulic cylinder 1 are detected. It is possible to detect a load from which the influence of is removed. And in the fluid leak detection apparatuses 100 and 200, since the fall of the seal function in the seal | sticker area | region 12 is determined based on the average load detected in this way, determination accuracy can be improved. In addition, since the number of wirings connected to the first load detection units 21 and 121 and the second load detection units 22 and 122 is small and the structure is simple, assembly work such as wiring can be easily performed, The manufacturing cost of the fluid leak detection devices 100 and 200 can be reduced.

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

  For example, the modification in the first embodiment may be applied to the second embodiment. Further, by combining the first embodiment and the second embodiment, both the axial load and the radial load acting on each of the seals 13 and 14 are detected, and the main seal 13 is based on these loads. The presence or absence of a fluid leak in may be determined.

  DESCRIPTION OF SYMBOLS 100,200 ... Fluid leak detection apparatus, 1 ... Hydraulic cylinder (fluid pressure apparatus), 3 ... Piston rod (shaft), 5 ... Rod side chamber 5 (sealed space), 7 ... Cylinder Head (housing), 8 ... 1st annular groove, 9 ... 2nd annular groove, 12 ... Sealing area, 13 ... Main seal, 14 ... Sub seal, 21, 21a-21d, 121 ... 1st load detection part, 22, 122 ... 2nd load detection part, 24 ... Pressure sensitive conductive rubber, 25 ... A pair of electrodes, 30 ... Control part, 32 ... Judgment part

Claims (7)

A fluid leak detection device for detecting a fluid leak in a first seal portion that seals a sealed space to which a fluid pressure is applied,
A first load detector for detecting a first load acting on the first seal portion;
A second load detection unit that detects a second load acting on a second seal portion that seals the sealed space at a position outside the first seal portion with respect to the sealed space;
A determination unit that determines a fluid leakage of the first seal portion based on the first load detected by the first load detection unit and the second load detected by the second load detection unit. A fluid leakage detection device characterized by the above.   When the difference between the first load detected by the first load detection unit and the second load detected by the second load detection unit falls below a predetermined reference value, the determination unit The fluid leak detection device according to claim 1, wherein the fluid leak is determined to be a fluid leak of the first seal portion. The first seal part and the second seal part seal between a shaft and a housing that slide-supports the shaft,
The first load detector detects an axial or radial load of the shaft acting on the first seal portion, and the second load detector detects a load detected by the first load detector. 3. The fluid leak detection device according to claim 1, wherein a load acting on the second seal portion is detected in the same direction. 4. The housing has a first annular groove that accommodates the first seal portion, and a second annular groove that accommodates the second seal portion,
The first load detector is housed in the first annular groove together with the first seal portion, and the second load detector is housed in the second annular groove together with the second seal portion. The fluid leakage detection device according to claim 3, wherein the fluid leakage detection device is a liquid leakage detection device.   5. The first load detector is formed integrally with the first seal portion, and the second load detector is formed integrally with the second seal portion. The fluid leak detection device according to any one of the above. The first load detection unit and the second load detection unit each have a pair of electrodes and a pressure-sensitive conductive rubber sandwiched between the pair of electrodes,
The resistance value between the pair of electrodes of the first load detector changes according to the load acting on the first seal portion, and the resistance of the second load detector according to the load acting on the second seal portion. 6. The fluid leakage detection device according to claim 1, wherein a resistance value between the pair of electrodes changes.   The said 1st load detection part and the said 2nd load detection part are each provided in cyclic | annular form along the said 1st seal | sticker part and the said 2nd seal | sticker part, It is any one of Claim 1 to 6 characterized by the above-mentioned. The fluid leakage detection device described.

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