Measuring device, diagnostic device, and filter apparatus

Abstract

By using this measuring device to be attached to a filter, the amount of water contained in oil can be measured.　The measuring device is provided to a filter apparatus having a filtering material for filtering oil and comprises: a housing attached to the filter apparatus; and a water-in-oil meter that is provided to the housing and that measures water contained in oil. The water-in-oil meter is provided to the housing. The housing has a columnar tip portion disposed inside the filter apparatus. The water-in-oil meter is provided at the tip portion of the housing so as to be in contact with oil.

Description

Measuring devices, diagnostic devices and filter devices

[0001] The present invention relates to a measuring device, a diagnostic device and a filter device.

[0002] Patent Document 1 discloses a filter device including a metal head provided to cover an opening of a filter case, a cylindrical filter medium provided in an internal space formed by the filter case and the head, an IC tag provided between the filter medium and a plate, and an antenna unit provided on the head having an antenna portion including an antenna capable of communicating with the IC tag. In this filter device, the antenna unit has a substantially cylindrical case at least a portion of which is inserted into the head, the antenna portion is provided adjacent to a first end which is one end of the case, the case is provided on the head so that the antenna portion is exposed when the head is viewed from the filter case side, and a metal plate is provided near the opening of the filter case, and the plate has a hole for exposing the IC tag.

[0003] Furthermore, Non-Patent Document 1 discloses that the amount of water contained in oil for vapor deposition can be electrically measured from the dielectric properties of the oil.

[0004] JP 2021-074675 Arai Tomokazu and Ichijo Bunjiro, "Research on a Capacitive Electric Moisture Meter for Oil," Journal of the Institute of Electrical Engineers of Japan, September 1959, Vol. 79, No. 852, pp. 1146-1150

[0005] The antenna unit described in Patent Document 1 has a measuring unit that measures the pressure or temperature in the space formed by the filter case and the head, so the measuring unit and antenna can be provided in the filter device simply by attaching the antenna unit to the head.The measuring unit measures the pressure and temperature, so it can detect whether the filter material in the filter device has become clogged beyond a predetermined amount.

[0006] In recent years, there has been a demand for monitoring not only the clogging of filter media but also the deterioration status of the oil filtered by the filter media. Furthermore, as shown in Non-Patent Document 1, it is known that the deterioration status of oil can be estimated by measuring the amount of water contained in the oil. However, it is difficult to measure the amount of water contained in the oil with the antenna unit described in Patent Document 1.

[0007] The present invention has been made in view of the above circumstances, and aims to provide a measuring device that can be attached to a filter and that can measure the amount of water contained in oil, and a diagnostic device that includes such a measuring device, as well as a filter device that is equipped with a small measuring device that can measure the amount of water contained in oil.

[0008] In order to solve the above problems, the measuring device of the present invention is, for example, a measuring device that is installed in a filter device having a filter material that filters oil, and is characterized in that it comprises a housing that is attached to the filter device, and a moisture-in-oil meter that is installed in the housing and measures the moisture contained in the oil, and the housing has a columnar tip that is positioned inside the filter device, and the moisture-in-oil meter is installed at the tip of the housing so as to come into contact with the oil.

[0009] In order to solve the above problem, the filter device of the present invention comprises, for example, the above-mentioned measuring device, a filter case having a substantially bottomed cylindrical case with an open upper end and a head provided on the case so as to cover the upper end of the case, and a filter element provided in the internal space of the filter case, the filter element having a cylindrical filter material, and the measuring device is characterized in that the tip portion is provided on the filter case so as to be exposed to the space formed by the filter case and the filter element.

[0010] According to the measuring device and filter device equipped with the measuring device of the present invention, a filter device including a filter case and a filter element (having a cylindrical filter material) installed in the internal space of the filter case has a housing for the measuring device attached to it, and the housing is equipped with a moisture-in-oil meter that measures the moisture contained in the oil filtered by the filter material. The cylindrical tip of the housing is located inside the filter device, and the moisture-in-oil meter is installed at the tip of the housing so as to come into contact with the oil. This allows the amount of moisture contained in the oil to be measured using the measuring device attached to the filter.

[0011] The present invention may also be a diagnostic device including the above-mentioned measurement device and a control unit that determines the deterioration of the oil based on the measurement results of the moisture-in-oil meter.

[0012] The moisture-in-oil meter may include a capacitor having two metal plate-shaped members, and the housing may have a cavity at the tip and a hole connecting the cavity to the outside of the housing and allowing the oil to flow into the cavity. The capacitor may be provided in the cavity, and the plate-shaped members may be arranged along a plane generally perpendicular to the central axis of the tip. The moisture-in-oil meter may be provided in a cavity near the tip disposed inside the filter device, and a hole may be provided in the housing connecting the cavity to the outside of the housing. This allows the moisture-in-oil meter to come into contact with the oil and measure the amount of moisture contained in the oil. Furthermore, by arranging the plate-shaped members along a plane generally perpendicular to the central axis of the tip, the surface area of ​​the plate-shaped members 72a is increased. This increases the accuracy of the dielectric constant measurement by the moisture-in-oil meter.

[0013] The moisture-in-oil meter may have a plurality of the capacitors, and all of the plate-like members may be arranged in parallel and adjacent to each other. By having a plurality of capacitors in the moisture-in-oil meter, the surface area of ​​the moisture-in-oil meter can be increased, and the dielectric constant measurement accuracy can be improved. Furthermore, by arranging all of the plate-like members in parallel and adjacent to each other, many capacitors can be provided in a narrow cavity.

[0014] The filter device may further include at least one of a viscosity sensor provided on a plate-shaped substrate for measuring the viscosity of the oil, a differential pressure detection unit for detecting the differential pressure between the upstream and downstream pressures of the filter medium of the filter device, or a temperature sensor for measuring the temperature of the oil. Because the measurement unit has at least one of a viscosity sensor, a differential pressure detection unit, or a temperature sensor, the estimation accuracy of the oil deterioration state is higher than that based solely on an oil moisture meter.

[0015] The plate-like substrate may have a vibrator with a double spiral structure in which a first member and a second member, each formed by spirally winding a columnar member, are provided facing each other, and a drive unit including a piezoelectric element provided on the first member. This prevents the viscosity sensor from protruding from the plate-like substrate, and allows the viscosity sensor to be provided in a narrow space.

[0016] The viscosity sensor includes a plate-shaped substrate provided with a vibrator having a double spiral structure, in which a first member and a second member are arranged facing each other, each of which is formed by spirally winding a columnar member, and a drive unit including a piezoelectric element provided on the first member. The viscosity sensor measures the viscosity of the oil. The plate-shaped substrate includes a first conductive pattern connected to the piezoelectric element and a second conductive pattern provided adjacent to the vibrator. The moisture-in-oil meter includes the second conductive pattern, which may include a capacitor having a pair of adjacent third and fourth conductive patterns. By providing the viscosity sensor having the double spiral structure vibrator and piezoelectric element and the second conductive pattern of the moisture-in-oil meter on the same plate-shaped substrate, the sensor unit 70 can be made thinner (smaller), and the tip of the housing can be made smaller. This reduces the amount of protrusion of the measurement unit into the filter device, thereby increasing the flexibility of the measurement unit's placement.

[0017] The housing may have a hollow portion provided in the tip portion and a hole connecting the hollow portion to the outside of the housing, and the plate-like substrate may be provided in the hollow portion, and the plate-like substrate may be provided along a plane substantially perpendicular to the central axis of the tip portion. By providing the plate-like substrate along a plane substantially perpendicular to the central axis of the tip portion, the hollow portion can be narrowed and the tip portion of the housing can be made smaller. This reduces the amount of protrusion of the measurement unit into the filter device, increasing the degree of freedom in positioning the measurement unit.

[0018] The moisture-in-oil meter may have a flexible sheet member made of an organic material, and the sheet member may include a capacitor having a pair of fifth and sixth conductive patterns formed by carbonizing the surface of the sheet member. By using a moisture-in-oil meter made of a flexible sheet member made of an organic material, the moisture-in-oil meter can be attached to the side of a non-flat housing, etc. This increases the flexibility in the placement of the moisture-in-oil meter. Furthermore, because the moisture-in-oil meter is compact, the tip of the measurement unit can be made smaller, increasing the flexibility in placement in the filter device.

[0019] According to the present invention, the amount of water contained in the oil can be measured by a measuring device attached to the filter.

[0020] 1 is a cross-sectional view showing an outline of the filter device 1 and the measurement unit 2. FIG. 1 is a cross-sectional view showing an outline of the measurement unit 2. FIG. 2 is a side view (partially enlarged) showing an outline of the measurement unit 2. FIG. 3 is a cross-sectional view (partially enlarged) showing an outline of the measurement unit 2. FIG. 4 is a block diagram showing the electrical configuration of the control unit 100. FIG. 5 is a cross-sectional view showing an outline of the measurement unit 3. FIG. 6 is a cross-sectional view (partially enlarged) showing an outline of the measurement unit 3. FIG. 7 is a plan view (viewed from the z direction) showing an outline of the sensor unit 70A. FIG. 8 is a diagram showing an outline of the viscosity sensor 74. FIG. 9 is a block diagram showing the electrical configuration of the control unit 100A. FIG. 10 is a cross-sectional view showing an outline of the measurement unit 4. FIG. 11 is a diagram showing an outline of the moisture-in-oil meter 75, where (a) is an exploded perspective view and (b) is a diagram showing the external appearance. FIG. 11 is a cross-sectional view showing an outline of the measurement unit 4A.

[0021] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. A filter device according to the present invention removes dust and other particles contained in oil, such as oil and fuel. Various filters, such as a fuel filter and a return filter, can be used in the filter device of this embodiment. Below, the filter device will be described using a return filter as an example. Furthermore, a measuring device according to the present invention is provided in the filter device and measures the amount of moisture contained in the oil filtered by the filter device.

[0022] First Embodiment Fig. 1 is a cross-sectional view showing an outline of a filter device 1 and a measurement unit 2. In Fig. 1, hatching indicating a cross section is partially omitted.

[0023] The filter device 1 mainly comprises a case 10, a filter element 20, a head 30, and an IC tag 40. The measurement unit 2 is attached to the filter device 1 when in use. The IC tag 40 is a small electronic component that can communicate with an antenna 90 (described in detail later) provided in the measurement unit 2 and that reads and writes data from a built-in memory in a non-contact manner using radio waves received from the antenna 90. Note that the IC tag 40 and the antenna 90 are not essential.

[0024] The case 10 is made of a highly corrosion-resistant metal (e.g., stainless steel) and is provided so as to protrude from the top surface of the tank 120 into the interior of the tank 120. Although the case 10 is integrated with the tank 120 in FIG. 1 , the case 10 may be formed as a separate part from the tank 120.

[0025] The case 10 is cylindrical with a bottom and an open top. The case 10 is hollow and has a head 30 that covers the opening at the top. The filter element 20 and other components are provided inside the case 10 and the head 30 (corresponding to the filter case of the present invention).

[0026] The case 10 has a bottom surface 11. An outflow portion 12 is provided so as to penetrate the bottom surface 11. The outflow portion 12 communicates the space inside the filter element 20 (space S2) with the space outside the case 10.

[0027] An inlet portion 13 is provided on a side surface of the case 10. The inlet portion 13 allows oil to flow into a space (space S1) formed by the filter case (here, the case 10) and the filter element 20.

[0028] The positions of the outlet portion 12 and the inlet portion 13 are not limited to these. The outlet portion 12 and the inlet portion 13 may be provided in any location as long as they are provided in the filter case, and may be provided in the head 30, for example.

[0029] The filter element 20 is a tubular (here, cylindrical) member and is provided in the internal space formed by the case 10 and the head 30. The filter element 20 mainly includes a filter medium 21, an inner cylinder 22, a plate 24, and a plate 25.

[0030] The filter material 21 is a member for filtering oil, and is a tubular (here, cylindrical) member with openings at both ends. The filter material 21 is formed by pleating filter paper made of synthetic resin, paper, etc., and connecting both ends of the pleated filter paper to form a cylinder. An inner tube 22 having holes formed over almost the entire area through which oil passes is provided inside the filter material 21. Note that the inner tube 22 is not essential. Alternatively, an outer tube having holes formed over almost the entire area through which oil passes may be provided outside the filter material 21.

[0031] A resin plate 24 is provided at the upper end of the filter medium 21. The plate 24 covers the upper end surfaces of the filter medium 21 and the inner cylinder 22. The plate 24 and the filter medium 21 are bonded together with an adhesive. Various types of organic adhesives whose main material is resin, rubber, or elastomer can be used as the adhesive.

[0032] The filter material contacts the underside of the plate 24, and the head 30 is inserted into the inner peripheral surface of the plate 24. The plate 24 also has a protrusion 24a that protrudes upward (toward the opposite side from the filter material 21), and an IC tag 40 is attached to the protrusion 24a.

[0033] A plate 25 is provided at the lower end of the filter medium 21. The plate 25 is a substantially hollow disk-shaped member that covers the filter medium 21 and the lower end surface of the inner cylinder 22. A recess 25a into which the filter medium 21 is inserted is formed on the upper surface of the plate 25. The recess 25a and the filter medium 21 are bonded together with an adhesive.

[0034] The outflow portion 12 is inserted into a hole 25b formed in the approximate center of the plate 25. The hole 25b and the outflow portion 12 are sealed by a seal member 91 (for example, an O-ring).

[0035] The head 30 is provided on the case 10 and the plate 24 so as to cover the opening on the top surface of the case 10 .

[0036] The head 30 is made of a highly corrosion-resistant metal (e.g., stainless steel). The head 30 mainly has a tubular portion 31, a cover 32, and an attachment portion 33. The tubular portion 31 is tubular (here, cylindrical) and fixed to the case 10. The cover 32 is a plate-like member and is provided on the upper side (+z side) of the tubular portion 31 so as to cover the hollow portion of the tubular portion 31. The cover 32 is detachable from the tubular portion 31. The cover 32 and the tubular portion 31 are sealed by a seal member (e.g., an O-ring) 93.

[0037] The cover 32 is provided with an attachment portion 33. The attachment portion 33 is a cylindrical member that protrudes downward from the cover 32. A valve 47 is provided at the tip of the attachment portion 33 (the end on the bottom surface 11 side). The attachment portion 33 is inserted into the hollow portion of the plate 24, and the valve 47 is inserted into the space S2. The attachment portion 33 and the plate 24 are sealed with a sealing member (e.g., an O-ring) 92. Normally, the valve 47 is closed, but if the filter media 21 becomes clogged and the pressure inside the case 10 increases, the valve 47 opens, allowing oil to flow from the space S1 to the space S2, thereby preventing damage to the filter device 1. The valve 47 is already known, so a description thereof will be omitted.

[0038] The inner diameter of the cylindrical portion 31 is larger than the outer diameter of the plate 24. A hole 31a is formed in the side surface of the cylindrical portion 31, penetrating the side surface. The measurement unit 2 is provided in the cylindrical portion 31 by inserting and fixing the measurement unit 2 into the hole 31a, and the tip of the measurement unit 2 is disposed inside the filter device (here, space S1). The cylindrical portion 31 (hole 31a) and the measurement unit 2 are sealed by sealing members (e.g., O-rings) 94 and 95.

[0039] A flow path 35 that connects the space S2 and the hole 31a is provided in the head 30. One end of the flow path 35 opens into the space S2, and the other end opens into the side surface of the hole 31a.

[0040] Next, the measurement unit 2 will be described. Fig. 2 is a cross-sectional view showing an outline of the measurement unit 2. Fig. 3 is a side view showing an outline of the measurement unit 2, and is an enlarged view of a portion of the measurement unit 2. Fig. 4 is a cross-sectional view showing an outline of the measurement unit 2, and is an enlarged view of a portion of the measurement unit 2. In Figs. 2 and 4, some of the hatching indicating the cross section is omitted.

[0041] The measurement unit 2 mainly includes a housing 50, a differential pressure detection unit 60, a sensor unit 70, and an antenna 90. Hereinafter, the longitudinal direction of the housing 50 will be referred to as the z direction, and two directions perpendicular to the z direction will be referred to as the x direction and the y direction. The x direction and the y direction are also perpendicular to each other.

[0042] The housing 50 mainly includes a case 51, covers 52 and 53, an insert member 54, and a fixing member 55. The case 51 has columnar portions 51v and 51w that are attached to the filter device 1 (see FIG. 2). The columnar portion 51v has a male thread 51x formed on its outer circumferential surface, and the male thread 51x is threadedly engaged with a female thread (not shown) formed in the hole 31a, thereby attaching the housing 50 to the hole 31a, and the tip of the housing 50 (here, at least a part of the cover 53 including the bottom surface 53c) is disposed inside the filter device 1 (here, space S1, see FIG. 1).

[0043] Covers 52 and 53 are cylindrical with bottoms and are provided on both ends of case 51. Cover 52 is provided to cover one end (+z side) of case 51, and cover 53 is provided to cover the other end (-z side) of case 51. Case 51 and cover 52 are sealed by a seal member (e.g., O-ring) 96, and case 51 and cover 53 are sealed by a seal member (e.g., O-ring) 97.

[0044] Holes 51a, 51b, 51c, 51d, grooves 51e, 51f, and 51k are provided in the case 51. Both ends of the case 51 are end faces 51m and 51n, respectively.

[0045] Hole 51a, hole 51b, and hole 51d are integrated, and hole 51d opens to end face 51n. Hole 51b is provided closer to end face 51m (+z side) than hole 51d, and hole 51a is provided closer to end face 51m than hole 51b. The diameter of hole 51b is larger than the diameter of hole 51a, and the diameter of hole 51d is larger than the diameter of hole 51b. One end of hole 51c opens to the bottom surface of hole 51b, and the other end opens to end face 51n. Hole 51k opens to end face 51m.

[0046] A groove 51e is provided in the hole 51d. Insertion members 54 are provided in the holes 51d and 51b, and a fixing member 55 is provided in the groove 51e. The insertion member 54 has a small diameter portion 54a and a large diameter portion 54b that is larger in diameter than the small diameter portion 54a. The large diameter portion 54b is inserted into the hole 51d, and the small diameter portion 54a is inserted into the hole 51b. With the insertion members 54 inserted into the holes 51d and 51b, the fixing member 55 is attached to the groove 51e, covering the end of the hole 51a on the end face 51n side. As a result, a hollow portion S3 with both ends covered is provided inside the columnar portions 51v and 51w.

[0047] The hollow portion S3 is provided with a differential pressure detection unit 60 that detects the differential pressure between the pressure on the upstream side and the pressure on the downstream side of the filter medium 21. The differential pressure detection unit 60 mainly has a detection unit 61, a spool 62, a magnet 63, and an elastic member 64.

[0048] The spool 62 has a cylindrical shape and is provided so as to be movable in the z direction inside the hollow portion S3. The outer peripheral surface 62b slides along the hole 51b, thereby moving the spool 62 in the z direction.

[0049] The spool 62 divides the hollow portion S3 into a space S4 and a space S5. One end of the hole 51f opens into the space S5. The case 51 and the insert member 54 are sealed by a seal member 98 (e.g., an O-ring).

[0050] The hole 51f penetrates the side surface of the columnar portion 51v in the radial direction (here, the x direction), and the other end of the hole 51f opens to the outer peripheral surface of the columnar portion 51v. As a result, the hole 51f communicates between the space S5 and the space S1 (upstream side of the filter medium 21, see FIG. 1). In addition, a hole (not shown) that penetrates the side surface of the columnar portion 51v in the radial direction communicates with the space S4 and the space S2 (downstream side of the filter medium 21, see FIG. 1) together with the flow path 35.

[0051] Elastic member 64 is, for example, a coil spring, and has one end attached to spool 62 and the other end attached to the bottom surface of hole 51b. Elastic member 64 applies a force in the −z direction to spool 62. Magnet 63 is provided on the surface of spool 62 facing the bottom surface of hole 51a, i.e., on the surface of spool 62 on the end surface 51m side.

[0052] The detection unit 61 is provided inside the hole 51k. The position of the detection unit 61 in the z direction is adjustable.

[0053] The detection unit 61 is provided with a magnetic field detection element 61a. The magnetic field detection element 61a detects changes in the magnetic field generated by the magnet 63. A reed switch, a Hall element, or the like may be used as the magnetic field detection element 61a. The detection result of the magnetic field detection element 61a is output to the outside of the measurement unit 2 via a signal line (not shown). Since the reed switch and the Hall element are already well known, a description thereof will be omitted.

[0054] The cover 53 is provided on the outside of the columnar portion 51v. At least a portion of the cover 53 corresponds to the tip of the measurement unit 2. The cover 53 is columnar in shape as a whole.

[0055] The cover 53 has a configuration in which one end of the cylindrical portion 53d is covered with the bottom surface 53c, and therefore, by providing the cover 53 to the case 51, a space S6 (corresponding to the hollow portion of the present invention) is formed at the tip of the housing 50. The sensor unit 70 and the antenna 90 are provided in this space S6. The sensor unit 70 and the differential pressure detection unit 60 are provided closer to the case 51 than the antenna 90.

[0056] The cover 53 is provided with holes 53a and 53b that penetrate radially through the side surface of the cover 53. Since the cover 53 is disposed inside the filter device 1 (space S1, see FIG. 1), the holes 53a and 53b communicate between the space S1 and the space S6.

[0057] The antenna 90 is provided along the bottom surface 53c of the cover 53. That is, the antenna 90 is provided in the space S6, i.e., at the tip of the measurement unit 2. The antenna 90 includes a wiring pattern (antenna coil pattern) formed on one surface of the antenna 90 (for example, the surface facing the bottom surface 53c). The antenna 90 is covered with resin (not shown) while provided on the bottom surface 53c. Therefore, the antenna 90 does not come into contact with oil.

[0058] The space S6 is also provided with a sensor unit 70. The sensor unit 70 has a temperature sensor 71 that measures the temperature of the oil and a moisture meter 72 in the oil.

[0059] The temperature sensor 71 is, for example, a plate-shaped substrate on which a thermocouple is mounted, and is provided along a plane that is approximately perpendicular to the central axis of the space S6 (here, the central axis ax of the cover 53).

[0060] The moisture-in-oil meter 72 has multiple (two in this example) capacitors 72b, each having two metal plate-like members 72a. In this embodiment, the moisture-in-oil meter 72 has four plate-like members 72a. The moisture-in-oil meter 72 can measure the dielectric constant of the oil by applying a DC voltage between the plate-like members 72a (electrodes) and measuring the amount of accumulated charge (capacitance).

[0061] The plate-like members 72a are arranged along a plane substantially perpendicular to the central axis ax. All the plate-like members 72a are arranged parallel to and adjacent to each other. By arranging the plate-like members 72a in this manner, the surface area of ​​the plate-like members 72a is increased, thereby improving the accuracy of measuring the dielectric constant.

[0062] The temperature sensor 71 and the moisture-in-oil meter 72 are provided adjacent to each other. In this embodiment, the temperature sensor 71 is provided closer to the columnar portion 51v (in the +z direction) than the moisture-in-oil meter 72, but the arrangement of the temperature sensor 71 and the moisture-in-oil meter 72 is not limited to this. For example, the moisture-in-oil meter 72 may be provided closer to the columnar portion 51v than the temperature sensor 71.

[0063] The temperature sensor 71 and the moisture-in-oil meter 72 may be provided separately. However, in order to accurately grasp the state of the oil, it is desirable to place the temperature sensor 71 and the moisture-in-oil meter 72 close to each other (for example, adjacent to each other).

[0064] A lead wire 81 is connected to the temperature sensor 71, and a lead wire 82 is connected to the moisture-in-oil meter 72 (plate-shaped member 72a). An antenna wire 83 is connected to the antenna coil pattern of the antenna 90. A hole 51c is provided in the case 51 along the central axis ax, and the lead wires 81, 82 and antenna wire 83 pass through the inside of the hole 51c and have their ends attached to a substrate 85.

[0065] An IC chip and the like (not shown) are mounted on the substrate 85. When radio waves are received from the IC tag 40, a received signal is generated on the substrate 85 via an antenna line, and the signal is output to the outside of the measurement unit 2 via a signal line (not shown). Similarly, the measurement results of the temperature sensor 71 and the moisture-in-oil meter 72 are also transmitted to the substrate 85.

[0066] The substrate 85 has a control unit 100 that performs processing. Fig. 5 is a block diagram showing the electrical configuration of the control unit 100. Functionally, the control unit 100 mainly has a measurement data acquisition unit 101, a deterioration estimation unit 102, and a storage unit 103.

[0067] The functional components of the control unit 100 may be further divided into more components depending on the processing content, or one component may execute the processing of multiple components.

[0068] The measurement data acquisition unit 101 acquires measurement results from the temperature sensor 71 and the moisture-in-oil meter 72 included in the sensor unit 70. The measurement results from the temperature sensor 71 and the moisture-in-oil meter 72 are output from the measurement data acquisition unit 101 to the deterioration estimation unit 102. The deterioration estimation unit 102 acquires the oil temperature based on the measurement results from the temperature sensor 71, and acquires the dielectric constant based on the measurement results from the moisture-in-oil meter 72. Methods for acquiring the temperature and dielectric constant from the measurement results from the temperature sensor 71 and the moisture-in-oil meter 72 are well known, and therefore will not be described here.

[0069] The memory unit 103 stores information related to the dielectric constant, including the temperature characteristics of the oil's dielectric constant (the relationship between temperature and dielectric constant), the relationship between the dielectric constant and the moisture content, and the relationship between the moisture content, the dielectric constant, and oil deterioration. The deterioration estimation unit 102 acquires information related to the dielectric constant from the memory unit 103 and estimates the degree of oil deterioration based on this information and the measurement results of the temperature sensor 71 and the moisture-in-oil meter 72. Various well-known techniques can be used as a method for determining oil deterioration based on the dielectric constant, etc., and therefore a description thereof will be omitted. The deterioration estimation unit 102 outputs the estimation result to the outside of the measurement unit 2 via a signal line (not shown).

[0070] For example, the control unit 100 may be configured with an IC mounted on the substrate 85. Alternatively, the control unit 100 may be configured with a computer system including an arithmetic unit such as a CPU (Central Processing Unit) for executing information processing, and storage devices such as a RAM (Random Access Memory) and a ROM (Read Only Memory). For example, the measurement results of the temperature sensor 71 and the moisture-in-oil meter 72 may be output to an external computer system via a signal line (not shown), and the deterioration state of the oil may be estimated by the computer system.

[0071] Next, the functions of the filter device 1 and the measurement unit 2 configured as described above will be described with reference to FIGS.

[0072] When the engine of the work machine is running, oil flows into space S1 inside case 10, as shown by the two-dot chain arrow in Figure 1. The oil that flows into space S1 flows from the outside to the inside of filter material 21, and dust and other particles in the oil are removed by filter material 21. The filtered oil then flows out into space S2. The filtered oil then flows out from outlet 12 into the tank interior.

[0073] Once the case 10 is filled with oil, the differential pressure detection section 60 of the measurement unit 2 shown in FIG. 2 detects the differential pressure between the pressure on the upstream side (space S1) and the pressure on the downstream side (space S2) of the filter medium 21.

[0074] When the filter material 21 is not clogged and the pressure in the spaces S1 and S5 is low, the spool 62 is pushed toward the insertion member 54 by the force of the elastic member 64, and the magnet 63 is located at the farthest position from the bottom surface of the hole 51a.

[0075] When the pressure in the space S1 increases due to clogging of the filter medium 21 or the like, the spool 62 moves toward the bottom of the hole 50a against the biasing force of the elastic member 64. The detection unit 61 detects the change in the magnetic field caused by the movement of the magnet 63 and transmits the detection result to an external device.

[0076] Because clogging of the filter medium 21 is roughly proportional to the operating time of the filter element 20, the operating time of the filter element 20 is measured using the IC tag 40, the antenna 90 reads the IC tag 40, and the reading result is transmitted from the measurement unit 2 to an external device. Furthermore, if a counterfeit product not equipped with the IC tag 40 is used as the replaced filter element, the IC tag 40 cannot be read, and the external device can display an error or prevent the filter device from operating. Furthermore, by reading the IC tag 40 attached to the replaced filter element 20, for example, the external device can determine that a filter element other than the specified filter element has been installed.

[0077] Furthermore, oil flows into space S6 through holes 53a and 53b, bringing the oil into contact with temperature sensor 71 and moisture-in-oil meter 72. This allows the sensor section 70 of measurement unit 2 to measure the oil temperature and dielectric constant. Because the dielectric constant is temperature-dependent, the degradation estimation section 102 corrects the dielectric constant measurement result from moisture-in-oil meter 72 based on the measurement result from temperature sensor 71 and estimates the degree of oil degradation based on this corrected result and information related to the dielectric constant. Furthermore, because the differential pressure detected by differential pressure detection section 60 changes due to clogging of filter media 21 caused by dust or increased viscosity due to oil degradation, the degradation estimation section 102 ultimately estimates the degree of oil degradation using the measurement result from differential pressure detection section 60.

[0078] According to this embodiment, by providing the filter device 1 with the measurement unit 2 having the moisture-in-oil meter 72, it is possible to measure the amount of moisture contained in the oil filtered by the filter media 21. As a result, the deterioration state of the oil can be estimated by the control unit 100. Furthermore, by using the measurement results of the temperature sensor 71, it is possible to improve the accuracy of estimating the deterioration state of the oil.

[0079] Furthermore, according to this embodiment, cover 53 is disposed inside filter device 1 (space S1), space S6 is formed inside cover 53, and hole 53a is provided in cover 53 that connects space S6 with the outside of housing 50 (space S1). This allows moisture-in-oil meter 72 to be provided in measurement unit 2 (here, space S6) so as to come into contact with the oil. This makes it possible to measure the amount of moisture in oil simply by including moisture-in-oil meter 72 in measurement unit 2 and providing measurement unit 2 in filter device 1. Similarly, the temperature sensor 71 is provided in measurement unit 2, and the temperature of oil can be measured simply by providing measurement unit 2 in filter device 1.

[0080] Furthermore, according to this embodiment, by providing the plate-shaped member 72 a along a plane substantially perpendicular to the central axis ax, the surface area of ​​the plate-shaped member 72 a is increased, thereby improving the measurement accuracy of the dielectric constant. Furthermore, since the moisture-in-oil meter 72 has a plurality of capacitors 72 b, the measurement accuracy of the dielectric constant can be improved.

[0081] Furthermore, according to this embodiment, by arranging all of the plate-like members 72a in parallel and adjacent to each other, it is possible to reduce the size (thinness) of the cover 53, i.e., the tip of the measurement unit 2. Furthermore, it is possible to provide many capacitors 72b in the narrow cavity (space S6).

[0082] In this embodiment, the differential pressure detection unit 60 is provided inside the case 51, but the differential pressure detection unit 60 is not essential. The temperature sensor 71 is also not essential. The measurement unit 2 is required to be provided with at least the moisture-in-oil meter 72. The sensor unit 70 may include sensors other than the temperature sensor 71 and the moisture-in-oil meter 72. For example, the sensor unit 70 may further include a viscosity sensor for measuring the viscosity of the oil. By providing the viscosity sensor on a plate-like substrate and arranging the plate-like substrate and the moisture-in-oil meter 72 adjacent to each other, the cover 53 can be made smaller (thinner). The viscosity sensor can be formed using actuators such as MEMS (Micro Electro Mechanical Systems) and QCM (Quartz Crystal Microbalance). Furthermore, by using a double-spiral structure vibrator and a drive unit including a piezoelectric element (see the viscosity sensor 74 described in detail below), the viscosity sensor can be thinned and prevented from protruding from the plate-like substrate. As a result, the viscosity sensor can be installed in a narrow space.

[0083] Furthermore, in this embodiment, the moisture-in-oil meter 72 has two capacitors 72b, but the number of capacitors 72b that the moisture-in-oil meter 72 has is not limited to this. The moisture-in-oil meter 72 may have only one capacitor 72b. However, since the surface area increases with the number of capacitors 72b and the measurement accuracy of the dielectric constant increases, it is desirable that the moisture-in-oil meter 72 have multiple capacitors 72b.

[0084] Second Embodiment In a second embodiment of the present invention, the moisture-in-oil meter is different from the measurement unit 2. A measurement unit 3 according to the second embodiment will be described below. Note that the same parts as those in the first embodiment are given the same reference numerals, and their description will be omitted. Also, the measurement unit 3 according to the second embodiment is attached to a filter device 1 in the same way as in the first embodiment, and therefore its description will be omitted.

[0085] 6 and 7 are cross-sectional views showing an outline of the measurement unit 3. Fig. 7 is an enlarged view of a portion of Fig. 6. The measurement unit 3 mainly includes a housing 50A, a differential pressure detection unit 60, a sensor unit 70A, and an antenna 90.

[0086] The housing 50A mainly includes a case 51, covers 52 and 53A, an insert member 54, and a fixing member 55. The cover 53A is provided on the outside of the columnar portion 51v so as to cover the -z side end of the case 51. Therefore, at least a portion of the cover 53A corresponds to the tip of the housing 50A. The cover 53A is columnar as a whole. By providing the cover 53A to the case 51, a space S7 (corresponding to the hollow portion of the present invention) is formed at the tip of the housing 50A. The space S7 has a lower height (distance in the z direction) and a smaller volume than the space S6. In addition, a hole 53a (not shown) is formed in the cover 53A.

[0087] A sensor unit 70A and an antenna 90 are provided in the space S7. The antenna 90 is provided along the bottom surface 53c, and the sensor unit 70A is provided closer to the case 51 than the antenna 90. The sensor unit 70A is provided along a plane that is approximately perpendicular to the central axis of the space S7 (here, the central axis ax of the cover 53A). One end of a lead wire 84 is provided to the sensor unit 70A. The lead wire 84 and the antenna wire 83 pass through the inside of the hole 51c, and the other end is provided to the substrate 85.

[0088] 8 is a plan view (viewed from the +z direction) showing an outline of the sensor unit 70A. The sensor unit 70A has a plate-shaped substrate 70a on which a moisture-in-oil meter 73 and a viscosity sensor 74 are provided. The lead wire 84 has two lead wires, one of which is connected to the moisture-in-oil meter 73 and the other of which is connected to the viscosity sensor 74.

[0089] The moisture-in-oil meter 73 has two electrode patterns 73a and 73b (corresponding to the second conductive pattern of the present invention) provided on a plate-shaped substrate 70a. The electrode patterns 73a and 73b each have a pattern 73c (corresponding to the third conductive pattern of the present invention) and a pattern 73d (corresponding to the fourth conductive pattern of the present invention). The patterns 73c and 73d are provided adjacent to each other. One end of a lead wire 84 is provided to each of the patterns 73c and 73d.

[0090] The patterns 73c and 73d are included in a capacitor. When a DC voltage is applied to the patterns 73c and 73d via the lead wire 84 and the electrode patterns 73a and 73b, an electric charge is accumulated between the patterns 73c and 73d. By measuring the amount of this electric charge (capacitance), the dielectric constant of the oil can be measured.

[0091] The viscosity sensor 74 measures the viscosity of the oil. The viscosity sensor 74 mainly includes a vibrator 741 and a pattern 742 (corresponding to the first conductive pattern of the present invention). The pattern 742 is provided adjacent to the vibrator 741, and one end of a lead wire 84 is provided to the pattern 742.

[0092] In this embodiment, the moisture-in-oil meter 73 and pattern 742 are provided on the +z surface of the plate-shaped substrate 70a, but the moisture-in-oil meter 73 and pattern 742 may also be provided on the -z surface of the plate-shaped substrate 70a.

[0093] 9 is a diagram showing an outline of the viscosity sensor 74. The vibrator 741 has a vibrating body 74a (corresponding to the first member of the present invention) and a force sensor 74b (corresponding to the second member of the present invention), which are formed by spirally winding a rod-shaped member. The vibrating body 74a and the force sensor 74b are arranged opposite each other, and have a double spiral structure. A gap of several μm to several hundred μm is provided between the vibrating body 74a and the force sensor 74b. The ends located at the outermost periphery (outer ends 74c, 74d) of the vibrating body 74a and the force sensor 74b are fixed to a substrate or the like, and the ends in the center (center ends 11e, 12f) are freely movable.

[0094] The oscillator 741 has a driving unit 743 and a displacement measuring unit 744. The oscillator 741 can be moved by the driving unit 743 in the z direction (a direction perpendicular to the paper surface of FIG. 9), that is, along the central axis of the oscillator 741.

[0095] The driving unit 743 mainly includes a plurality of piezoelectric elements 74g and a connecting portion 74h that connects the piezoelectric elements 74g. The connecting portion 74h is connected to the pattern 73c. ​​The piezoelectric elements 74g are connected to a power source via the connecting portion 74h.

[0096] The connecting portion 74h extends along the longitudinal direction of the vibrating body 74a. Each of the piezoelectric elements 74g is tilted at approximately 45 degrees with respect to the longitudinal direction of the vibrating body 74a. The plurality of piezoelectric elements 74g are arranged side by side along the longitudinal direction of the vibrating body 74a. The piezoelectric elements 74g generate torsional deformation in the vibrating body 74a, causing a large deformation of the center end 11e of the vibrating body 74a in the z direction.

[0097] The displacement measuring unit 744 is a piezoelectric thin film provided on the surface of each of the vibrating body 74 a and the force sensing body 74 b. The displacement measuring unit 744 mainly includes a plurality of displacement sensors 74 i and a connecting portion 74 j that connects the displacement sensors 74 i. The connecting portion 74 j is connected to the pattern 73 d.

[0098] The connecting portion 74j extends along the longitudinal direction of the vibrating body 74a or the force sensing body 74b. The displacement sensor 74i is inclined at approximately 45 degrees with respect to the longitudinal direction of the vibrating body 74a or the force sensing body 74b, respectively. Furthermore, the multiple displacement sensors 74i are arranged side by side along the longitudinal direction of the vibrating body 74a or the force sensing body 74b. Because deformation due to torsion of the piezoelectric element 74g occurs in the longitudinal direction of the vibrating body 74a, by arranging the displacement sensors 74i at an angle of approximately 45 degrees with respect to the direction of deformation of the vibrating body 74a, the amount of deformation of the vibrating body 74a at the position where the displacement sensor 74i is provided can be efficiently measured by each displacement sensor 74i.

[0099] Returning to the explanation of Fig. 8, the oscillator 741 and the patterns 73c and 73d are provided adjacent to each other, which allows the viscosity and water content to be measured using oil in a similar environment.

[0100] The substrate 85 has a control unit 100A that performs processing. Fig. 10 is a block diagram showing the electrical configuration of the control unit 100A. Functionally, the control unit 100A mainly has a measurement data acquisition unit 101A, a deterioration estimation unit 102A, and a storage unit 103A. Note that the functional components of the control unit 100A may be further divided into more components depending on the processing content, or one component may perform the processing of multiple components.

[0101] The measurement data acquisition unit 101A acquires measurement results from the moisture-in-oil meter 73 and viscosity sensor 74 included in the sensor unit 70A. The measurement results from the moisture-in-oil meter 73 and viscosity sensor 74 are output from the measurement data acquisition unit 101A to the deterioration estimation unit 102A. The deterioration estimation unit 102A acquires the dielectric constant from the measurement results from the moisture-in-oil meter 73, and acquires the oil viscosity from the measurement results from the viscosity sensor 74. The method of acquiring viscosity from the measurement results from the viscosity sensor 74 is well known, so a description thereof will be omitted.

[0102] The memory unit 103A stores information on the relationship between the dielectric constant and water content of the oil, information on the dielectric constant including the relationship between the water content and the dielectric constant and oil degradation, and information on the viscosity including the relationship between the viscosity of the oil and the degradation. The degradation estimation unit 102A acquires information on the dielectric constant and viscosity from the memory unit 103A and detects the degree of oil degradation based on this information and the measurement results of the sensor unit 70A. Various well-known techniques can be used to determine oil degradation based on the dielectric constant, viscosity, etc., so a description thereof will be omitted. The degradation estimation unit 102A outputs the estimation results to the outside of the measurement unit 2 via a signal line (not shown).

[0103] For example, the control unit 100A can be configured with an IC mounted on the substrate 85. The control unit 100A may also be configured with a computer system including an arithmetic unit such as a CPU (Central Processing Unit) for executing information processing, and a storage device such as a RAM (Random Access Memory) or a ROM (Read Only Memory). For example, the measurement results of the moisture-in-oil meter 73 and the viscosity sensor 74 may be output to an external computer system via a signal line (not shown), and the deterioration state of the oil may be estimated by the computer system.

[0104] Next, the functions of the filter device 1 and measurement unit 3 configured as described above will be explained. When the engine of the work machine is running and oil is filling the case 10, the differential pressure detection section 60 of the measurement unit 3 detects the differential pressure between the pressure on the upstream side (space S1) of the filter element 21 and the pressure on the downstream side (space S2). If the pressure in space S1 increases due to clogging of the filter element 21, the spool 62 moves toward the bottom of the hole 50a against the biasing force of the elastic member 64. The detection unit 61 detects changes in the magnetic field caused by the movement of the magnet 63 and transmits the detection results to an external device. The IC tag 40 also measures the operating time of the filter element 20, and the antenna 90 reads the IC tag 40, and the measurement unit 2 transmits the reading results to an external device.

[0105] The sensor unit 70A measures the dielectric constant and viscosity of the oil. Because oil flows into the space S7 through the hole 53a, the oil comes into contact with the sensor unit 70A. Based on the measurement results of the sensor unit 70A, the control unit 100A measures the dielectric constant and viscosity of the oil, allowing the deterioration status of the oil to be estimated. Furthermore, because the sensor unit 70A includes an actuator (vibrator 741), the flow of oil into and out of the space S7 is made easier. Therefore, the oil present in the space S7 is successively replaced, making it possible to measure the current dielectric constant and viscosity of the oil.

[0106] The deterioration estimation unit 102A estimates the degree of oil deterioration based on the measurement results from the moisture-in-oil meter 73. Furthermore, because the viscosity of oil increases as oxidation and deterioration progress, the deterioration estimation unit 102A estimates the degree of oil deterioration based on the measurement results from the viscosity sensor 74. The deterioration estimation unit 102A then corrects the measurement results from the moisture-in-oil meter 73 using the measurement results from the viscosity sensor 74, and finally estimates the degree of oil deterioration.

[0107] According to this embodiment, by providing the filter device 1 with the measurement unit 3 having the moisture-in-oil meter 73, it is possible to measure the amount of moisture contained in the oil filtered by the filter medium 21. As a result, the deterioration state of the oil can be estimated by the control unit 100A. Furthermore, because the measurement unit 3 has the viscosity sensor 74, the estimation accuracy of the deterioration state of the oil is higher than that based solely on the measurement results of the moisture-in-oil meter 73.

[0108] Furthermore, according to this embodiment, the moisture-in-oil meter 73 and viscosity sensor 74 are provided on the plate-shaped substrate 70a, and the sensor unit 70A is thin (miniaturized), so the space S7, i.e., the cover 53A, can be made smaller. This reduces the amount of protrusion of the measurement unit 3 into the filter device 1, increasing the flexibility in the placement of the measurement unit 3. For example, it becomes possible to place the tip (at least a part of the cover 53A) in a narrow space, allowing the measurement unit 3 to be placed in a variety of locations.

[0109] Furthermore, according to this embodiment, the viscosity sensor 74 has a driving unit including a vibrator with a double spiral structure and a piezoelectric element, so that the viscosity sensor 74 does not protrude from the plate-like substrate 70a, and as a result, the viscosity sensor 74 can be provided in the narrow space S7.

[0110] In this embodiment, the sensor unit 70A includes the moisture-in-oil meter 73 and the viscosity sensor 74, but the configuration of the sensor unit 70A is not limited to this. For example, the sensor unit 70A may include a temperature sensor that measures the temperature of the oil. Because viscosity changes with temperature (for example, viscosity decreases when the antifoaming agent deteriorates), if the sensor unit 70A includes a temperature sensor, oil deterioration can be more accurately estimated. Furthermore, the viscosity sensor 74 may be configured with an actuator other than the vibrator 741 (for example, a MEMS). Furthermore, similar to the measurement unit 2, the differential pressure detection unit 60 is not essential in this embodiment either.

[0111] <Third embodiment> In the third embodiment of the present invention, the moisture-in-oil meter is different from the filter device 1. A measurement unit 4 according to the third embodiment will be described below. Note that the same parts as those in the first embodiment are given the same reference numerals, and their description will be omitted. Also, the fact that the measurement unit 4 according to the third embodiment is attached to the filter device 1 is the same as in the first embodiment, and therefore its description will be omitted.

[0112] 11 is a cross-sectional view showing an outline of the measurement unit 4. The measurement unit 4 mainly includes a housing 50B, a differential pressure detection unit 60, a sensor unit 70B, and an antenna 90.

[0113] The housing 50B mainly includes a case 51, covers 52 and 53B, an insert member 54, and a fixing member 55. The cover 53B is provided on the outside of the columnar portion 51v so as to cover the -z side end of the case 51. Therefore, at least a portion of the cover 53B corresponds to the tip of the housing 50B. The cover 53B is columnar as a whole. By providing the cover 53B to the case 51, a space S8 (corresponding to the cavity of the present invention) is formed inside the tip (here, the cover 53B). The space S8 has a lower height (distance in the z direction) and a smaller volume than the space S6. In addition, a hole 53a (not shown) is formed in the cover 53B.

[0114] The space S8 is provided with a sensor unit 70B and an antenna 90. The antenna 90 is provided along the bottom surface 53c, and the sensor unit 70B is provided closer to the case 51 than the antenna 90. The sensor unit 70B mainly includes a temperature sensor 71 and a moisture-in-oil meter 75. One end of a lead wire 82 is connected to the moisture-in-oil meter 75.

[0115] The moisture-in-oil meter 75 is flexible and is provided along the inner peripheral surface of the cover 53B. Figure 12 is a diagram showing an outline of the moisture-in-oil meter 75, where (a) is an exploded perspective view and (b) is a diagram showing the external appearance.

[0116] The moisture-in-oil meter 75 is a flexible sheet member made of an organic material. In this embodiment, the moisture-in-oil meter 75 mainly includes an organic substrate 75 a and a film 75 b. However, the film 75 b is not essential.

[0117] The organic substrate 75a and the film 75b are each formed of an organic material. While various materials can be used as the organic material, in this embodiment, polyimide is used for the organic substrate 75a and acrylic is used for the film 75b. The organic substrate 75a and the film 75b are formed in a sheet shape to provide flexibility. In this embodiment, the organic substrate 75a is 50 μm thick and the film 75b is 100 μm thick, but the thickness is not limited to these.

[0118] A pair of conductive patterns 75c (corresponding to a fifth conductive pattern of the present invention) and 75d (corresponding to a sixth conductive pattern of the present invention) are formed on the organic substrate 75a. The conductive patterns 75c and 75d are formed by carbonizing the surface of the organic substrate 75a. One end of a lead wire 82 is provided on the conductive patterns 75c and 75d.

[0119] Conductive patterns 75c and 75d are adjacent to each other and are included in a capacitor. When a DC voltage is applied to conductive patterns 75c and 75d via lead wire 82, an electric charge accumulates between conductive patterns 75c and 75d. By measuring the amount of this electric charge (capacitance), the dielectric constant of the oil can be measured.

[0120] The substrate 85 has a control unit 100 that performs processing. In the control unit 100, a measurement data acquisition unit 101 acquires measurement results from the temperature sensor 71 and the moisture-in-oil meter 75, and a deterioration estimation unit 102 acquires the oil temperature from the measurement results of the temperature sensor 71 and the dielectric constant from the measurement results of the moisture-in-oil meter 75, and estimates oil deterioration based on this information and the information stored in the memory unit 103.

[0121] Next, the functions of the filter device 1 and measurement unit 4 configured as described above will be explained. When the engine of the work machine is running and oil is filling the case 10, the differential pressure detection section 60 of the measurement unit 4 detects the differential pressure between the pressure on the upstream side (space S1) of the filter element 21 and the pressure on the downstream side (space S2). If the pressure in space S1 increases due to clogging of the filter element 21, the spool 62 moves toward the bottom of the hole 50a against the biasing force of the elastic member 64. The detection unit 61 detects changes in the magnetic field caused by the movement of the magnet 63 and transmits the detection results to an external device. The IC tag 40 also measures the operating time of the filter element 20, and the antenna 90 reads the IC tag 40, and the measurement unit 2 transmits the reading results to an external device.

[0122] The sensor unit 70B measures the temperature and dielectric constant of the oil. Because oil flows into the space S8 through the hole 53a, the oil comes into contact with the sensor unit 70B. As a result, the control unit 100 measures the temperature and dielectric constant of the oil based on the measurement results of the sensor unit 70B, and the deterioration state of the oil can be estimated.

[0123] According to this embodiment, the filter device 1 is provided with a measurement unit 4 having a moisture-in-oil meter 75, which allows the amount of moisture contained in the oil filtered by the filter medium 21 to be measured. As a result, the control unit 100 can estimate the deterioration state of the oil.

[0124] Furthermore, according to this embodiment, the moisture-in-oil meter 75 is flexible, so it can be curved along the wall surface of the cover 53B. By providing the moisture-in-oil meter 75 on the wall surface of the cover 53B, the space S8, i.e., the cover 53B, can be made smaller. This reduces the amount by which the measurement unit 4 protrudes into the filter device 1, allowing the measurement unit 4 to be placed in various locations on the filter device 1.

[0125] In this embodiment, the moisture-in-oil meter 75 is provided on the wall surface of the cover 53B, but the location of the moisture-in-oil meter 75 is not limited to this. Figure 13 is a cross-sectional view showing an outline of a measurement unit 4A according to a modified example. The measurement unit 4 and the measurement unit 4A differ only in the position of the moisture-in-oil meter 75 and the size of the cover 53C of the housing 50C.

[0126] To protect the antenna coil pattern, etc., the antenna 90 is provided on the bottom surface 53c of the cover 53C and is covered with resin 91. The moisture-in-oil meter 75 is attached to the surface 91a of the resin 91. Because the moisture-in-oil meter 75 is flexible, it can be attached to the surface 91a even if the surface 91a is not flat.

[0127] Furthermore, because the moisture-in-oil meter 75 is thin, the space for providing the sensor unit 70B, i.e., the height of the cover 53C, can be made thinner (smaller) than the cover 53B. As a result, the housing 50C can be made even smaller. Furthermore, the amount by which the measurement unit 4A protrudes into the filter device 1 is reduced, making it easier to position the measurement unit 4A.

[0128] Furthermore, the measurement units 4 and 4A according to the present embodiment and the modified examples do not necessarily include the differential pressure detection unit 60 and the temperature sensor 71, as with the measurement unit 2. The sensor unit 70B may also include sensors other than the temperature sensor 71 and the moisture-in-oil meter 75.

[0129] Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configurations are not limited to these embodiments, and design modifications within the scope of the gist of the present invention are also included. For example, the above examples have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add, delete, or replace other configurations to the configuration of one embodiment.

[0130] Furthermore, "substantially" is a concept that includes not only cases where something is strictly identical, but also errors or deformations that do not cause loss of identity. For example, "cylindrical" is not limited to cases where something is strictly cylindrical, but also includes cases where something can be regarded as identical to a cylindrical shape. Furthermore, for example, when simply expressing something as orthogonal, parallel, coincident, etc., it includes not only cases where something is strictly orthogonal, parallel, coincident, etc., but also cases where something is approximately parallel, approximately orthogonal, approximately coincident, etc.

[0131] Furthermore, "vicinity" means including a certain range (which can be arbitrarily determined) near a reference position. For example, "near an edge" is a concept indicating a certain range near the edge, which may or may not include the edge.

[0132] DESCRIPTION OF SYMBOLS 1: Filter device 2, 3, 4, 4A: Measuring unit 10: Case 11: Bottom surface 11e: Center end 12: Outlet portion 12f: Center end 13: Inlet portion 20: Filter element 21: Filtering material 22: Inner tube 24, 25: Plate 24a: Convex portion 25a: Concave portion 25b: Hole 30: Head 31: Cylindrical portion 31a: Hole 32: Cover 33: Mounting portion 35: Flow path 40: IC tag 47: Valve 50, 50A, 50B, 50C: Housing 51: Case 52, 53, 53A, 53B, 53C: Cover 50a, 51a, 51b, 51d, 51k: Hole 51c, 51f, 53a, 53b: Hole 51e: Groove 51m, 51n: End surface 51v, 51w: Pillar portion 51x: Male thread 53d: Cylindrical portion 53c: Bottom surface 54: Insertion member 54a: Small diameter portion 54b: Large diameter portion 55: Fixing member 60: Differential pressure detection portion 61: Detection unit 61a: Magnetic field detection element 62: Spool 62b: Outer circumferential surface 63: Magnet 64: Elastic member 70, 70A, 70B: Sensor portion 70a: Plate-shaped substrate 71: Temperature sensor 72: Moisture-in-oil meter 72a: Plate-shaped member 72b: Capacitor 73: Moisture-in-oil meter 73a, 73b: Electrode pattern 73c: Pattern 73d : Pattern 74 : Viscosity sensor 74a : Vibrating body 74b : Force sensing body 74c, 74d : Outer end 74g : Piezoelectric element 74h : Connecting part 74i : Displacement sensor 74j : Connecting part 75 : Moisture-in-oil meter 75a : Organic substrate 75b : Film 75c, 75d : Conductive pattern 81, 82, 84 : Lead wire 83 : Antenna wire 85 : Substrate 90 : Antenna 91 : Resin 91a : Surface 100, 100A : Control unit 101, 101A : Measurement data acquisition unit 102, 102A : Deterioration estimation unit 103 : Memory unit 103A : Memory unit 120 : Tank 741 : Vibrator 742 : Pattern 743 : Drive unit 744 : Displacement measurement unit

Claims

1. A measuring device that is installed in a filter device having a filter medium for filtering oil, comprising: a housing that is attached to the filter device; and a moisture-in-oil meter that is installed in the housing and measures the moisture contained in the oil, wherein the housing has a tip that is positioned inside the filter device, and the moisture-in-oil meter is installed at the tip of the housing so as to come into contact with the oil.

2. The measuring device described in claim 1, characterized in that the moisture-in-oil meter has a capacitor having two metal plate-like members, the casing has a hollow portion provided in the tip portion and a hole that connects the hollow portion to the outside of the casing and allows the oil to flow into the hollow portion, the capacitor is provided in the hollow portion, and the plate-like members are provided along a plane approximately perpendicular to the central axis of the tip portion.

3. The measuring device according to claim 2, characterized in that the moisture-in-oil meter has a plurality of the capacitors, and all of the plate-like members are arranged in parallel and adjacent to each other.

4. The measuring device according to any one of claims 1 to 3, further comprising at least one of a viscosity sensor for measuring the viscosity of the oil, a differential pressure detection unit for detecting the differential pressure between the upstream pressure and the downstream pressure of the filter medium possessed by the filter device, or a temperature sensor for measuring the temperature of the oil.

5. The measuring device according to claim 1, further comprising a viscosity sensor for measuring the viscosity of the oil, comprising: a plate-like substrate provided with a vibrator having a double spiral structure in which a first member and a second member formed by spirally winding a columnar member are arranged opposite each other; and a driving unit including a piezoelectric element provided on the first member, the plate-like substrate having a first conductive pattern connected to the piezoelectric element and a second conductive pattern provided adjacent to the vibrator, the moisture-in-oil meter including the second conductive pattern, and the second conductive pattern including a capacitor having a pair of third and fourth conductive patterns provided adjacent to each other.

6. The measuring device according to claim 5, characterized in that the housing has a hollow portion provided in the tip portion and a hole connecting the hollow portion to the outside of the housing, the plate-like substrate is provided in the hollow portion, and the plate-like substrate is provided along a plane approximately perpendicular to the central axis of the tip portion.

7. The measurement device according to claim 1, characterized in that the moisture-in-oil meter has a flexible sheet member formed of an organic material, and the sheet member includes a capacitor having a pair of fifth and sixth conductive patterns formed by carbonizing the surface of the sheet member.

8. A diagnostic device comprising: a measuring device according to any one of claims 1 to 7; and a control unit which calculates the electrical conductivity of the oil based on the measurement results of the oil moisture meter and determines the deterioration of the oil based on the electrical conductivity.

9. A filter device comprising: a measuring device as defined in any one of claims 1 to 7; a filter case having a substantially bottomed cylindrical case with an open upper end and a head provided on the case so as to cover the upper end of the case; and a filter element provided in the internal space of the filter case, the filter element having a cylindrical filter medium, wherein the measuring device is provided on the filter case such that the tip portion is exposed to the space formed by the filter case and the filter element.

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