Sensor unit

Abstract

The purpose of the present invention is to provide a sensor unit having high detection sensitivity. This sensor unit 1 is characterized by comprising a base body 3 having a base part 31 and a columnar part 32 that protrudes from the base part 31, a linear sensor 2 wound around the columnar part 32, a peripheral wall part 5 that surrounds the linear sensor 2 in a state of contacting the linear sensor 2 from the columnar-part 32 side, and a lid body 4 that is disposed facing the base part 31 and sandwiches the linear sensor 2 together with the base part 31.

Description

Technical Field

[0001] The present invention relates to a sensor unit provided with a linear sensor.

Background Art

[0002] A linear sensor using an internal conductor, a piezoelectric body provided in contact with the outer peripheral surface of the internal conductor, and an external conductor provided in contact with the outer peripheral surface of the piezoelectric body as a sensor wire is known (see, for example, Patent Document 1, etc.). This linear sensor has the property that when a load is applied from the outside, the piezoelectric body is deformed and a voltage is induced between the internal conductor and the external conductor. Utilizing this property, it has been considered to use the linear sensor as a pressure sensor for detecting pressure or a vibration sensor for detecting vibration. In addition, instead of the sensor wire using a piezoelectric body, it has also been considered to use a resistance wire such as conductive rubber or a capacitor wire as the sensor wire to constitute a linear sensor. On the other hand, in recent years, by collecting and analyzing state information such as the vibration of a machine tool, it is possible to predict in advance the deterioration of consumable parts such as tools used in the machine tool and the failure of the machine tool, or to formulate a maintenance plan for more efficiently performing component replacement. Technologies are also being studied for improving the efficiency of failure prediction and maintenance work by collecting and analyzing state information in devices such as robots, agricultural machines, vehicles, and home appliances. Hereinafter, devices such as machine tools, robots, agricultural machines, vehicles, and home appliances are collectively referred to as the detected object. Furthermore, it has also been considered to use a sensor unit composed of a linear sensor and two members sandwiching the linear sensor (see, for example, Patent Document 2, etc.).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

[0004] However, the sensor unit described in Patent Document 2 simply sandwiches a linear sensor between two members, so the linear sensor and each member are in contact only in the direction of sandwiching between the two members. As a result, there is a problem in that the detection sensitivity to vibrations that have amplitude directions other than the sandwiching direction is low.

[0005] In view of the above circumstances, the present invention aims to provide a sensor unit with high detection sensitivity. [Means for solving the problem]

[0006] The sensor unit of the present invention, which solves the above objective, comprises a base having a base portion and a columnar portion protruding from the base, A linear sensor wrapped around the columnar portion, A peripheral wall portion surrounding the linear sensor, in contact with the linear sensor from the side of the columnar portion, The device is characterized by comprising a cover positioned opposite the base and sandwiching the linear sensor between itself and the base.

[0007] With the linear sensor surrounded by the base and the peripheral wall, the linear sensor is sandwiched between the cover and the base, so that the linear sensor is pressed not only against the cover and the base, but also against the columnar portion and the peripheral wall. Therefore, vibrations transmitted from the object to be detected to the sensor unit are easily transmitted to the linear sensor from the columnar portion and the peripheral wall. As a result, in addition to vibrations having an amplitude direction in the direction of clamping by the cover, vibrations having an amplitude direction other than the clamping direction can also be detected by the linear sensor with high sensitivity, so that the entire sensor unit can detect vibrations with high detection sensitivity.

[0008] Here, the cover may press the linear sensor against the base. Alternatively, the cover may press the linear sensor in the direction opposite to the protruding direction of the columnar portion. In addition, the cover may press the linear sensor to the extent that it causes slight deformation. Furthermore, the linear sensor may have a signal cable connected to it, and the peripheral wall portion may have a guide portion that guides the linear sensor or the signal cable to the outside of the peripheral wall portion. Furthermore, the linear sensor may be wrapped around the columnar portion multiple times. Also, the base portion may be more rigid than the linear sensor. Similarly, the columnar portion may be more rigid than the linear sensor. Similarly, the peripheral wall portion may be more rigid than the linear sensor.

[0009] In the sensor unit of the present invention, the base body has a first pressing body, The cover may sandwich the linear sensor between itself and the base via the first pressing body.

[0010] Furthermore, in the sensor unit of the present invention, the first pressing body may be made of a material that is more elastically deformable than the base.

[0011] This prevents the linear sensor, which is sandwiched between the cover and the first pressing body, from being damaged.

[0012] Here, the first pressing body may be made of an elastic material such as rubber.

[0013] Furthermore, in the sensor unit of the present invention, the first pressing body may have an inclined surface that is inclined with respect to the clamping direction of the lid.

[0014] Because the linear sensor is pressed against at least one of the columnar portion and the peripheral wall portion by the inclined surface of the first pressing body, vibrations transmitted from the object to be detected to the columnar portion and the peripheral wall portion are more easily transmitted to the linear sensor. As a result, the detection sensitivity of this sensor unit is increased.

[0015] In the sensor unit of the present invention, the cover may have a second pressing body, and the linear sensor may be sandwiched between the base and the second pressing body.

[0016] Furthermore, in the sensor unit of the present invention, the second pressing body may be made of a material that is more elastically deformable than the base.

[0017] This prevents the linear sensor, which is sandwiched between the base and the second pressing body, from being damaged.

[0018] Here, the second pressing body may be made of an elastic material such as rubber.

[0019] The second pressing body may have an inclined surface that is inclined with respect to the direction in which the lid is clamped.

[0020] Because the inclined surface of the second pressing body presses the linear sensor against at least one of the columnar portion and the peripheral wall portion, vibrations transmitted from the object to be detected to the columnar portion and the peripheral wall portion are more easily transmitted to the linear sensor. As a result, the detection sensitivity of this sensor unit is increased.

[0021] Furthermore, in the sensor unit of the present invention, the peripheral wall portion may be formed integrally with the cover.

[0022] This sensor unit has fewer parts, and because the side of the columnar portion is open before the cover, which is integrally formed with the peripheral wall portion, is attached, the linear sensor can be easily wrapped around the columnar portion. For this reason, this sensor unit can be produced at a low cost.

[0023] Also, in the sensor unit of the present invention, the peripheral wall portion may be integrally formed with the base body.

[0024] Since the number of parts of this sensor unit is reduced, the sensor unit can be produced at a low cost.

[0025] Also, in the sensor unit of the present invention, the lid body may have a screw portion.

[0026] With the screw portion, this sensor unit can be easily attached to the detection object.

[0027] Also, in the sensor unit of the present invention, the peripheral wall portion may have a thread formed on its outer peripheral surface.

[0028] With the thread formed on the peripheral wall portion, this sensor unit can be easily attached to the detection object.

Advantages of the Invention

[0029] According to the present invention, a sensor unit with high detection sensitivity can be provided.

Brief Description of the Drawings

[0030] [Figure 1] It is a cross-sectional view showing the structure of the linear sensor. [Figure 2] It is a diagram showing an example in which an insulating member and a conductor member are provided for an end portion of the linear sensor on a side not connected to the signal cable. [Figure 3] (a) is a plan view of the sensor unit of the present embodiment, and (b) is a cross-sectional view taken along line A-A of the same figure (a). [Figure 4] It is an exploded cross-sectional view of the sensor unit shown in FIG. 3(b) disassembled. [Figure 5]Figure 3 is an example of an installation diagram showing the sensor unit attached to the object to be detected using a fixing device. [Figure 6] This is a cross-sectional view of the sensor unit according to the second embodiment. [Figure 7] This is a cross-sectional view of the sensor unit according to the third embodiment. [Figure 8] (a) is a plan view of the sensor unit of the fourth embodiment, and (b) is a cross-sectional view of BB in Figure (a). [Figure 9] This is a cross-sectional view of the sensor unit according to the fifth embodiment. [Figure 10] (a) is a bottom view of the sensor unit of the sixth embodiment, and (b) is a cross-sectional view of the CC of the same figure (a). [Figure 11] (a) is a bottom view of the sensor unit of the seventh embodiment, and (b) is a DD cross-sectional view of the same figure (a). [Modes for carrying out the invention]

[0031] The embodiments of the present invention will be described below with reference to the drawings. First, the linear sensor used in the sensor unit of this embodiment will be described.

[0032] Figure 1 is a cross-sectional view showing the structure of a linear sensor.

[0033] As shown in Figure 1, the linear sensor 2 comprises a sensor wire 20, an inner sheath 24, a shielding cover 25, and an outer sheath 26. The sensor wire 20 is composed of an inner conductor 21, a piezoelectric element 22, and an outer conductor 23. As shown in Figure 1, the inner conductor 21 is located in the center of the linear sensor 2 and is composed of seven conductor wires 211. The piezoelectric element 22 is provided on the outer circumference of the inner conductor 21. The outer conductor 23 is provided on the outer circumference of the piezoelectric element 22.

[0034] The seven conductor wires 211 all have a diameter of 10 μm. Of these, four are stainless steel conductor wires 211S, and the remaining three are copper conductor wires 211C. In Figure 1, the stainless steel conductor wires 211S are indicated by hatching that slopes downward to the left, and the copper conductor wires 211C are indicated by hatching that slopes downward to the right. In the internal conductor 21 shown in Figure 1, the conductor wire positioned in the center is made of stainless steel conductor wire 211S (stainless steel wire), while the conductor wires positioned on the outer perimeter alternate between stainless steel conductor wire 211S and copper conductor wire 211C. The copper conductor wire 211C has lower electrical resistance and is softer than the stainless steel conductor wire 211S. Conversely, the stainless steel conductor wire 211S has higher electrical resistance than the copper conductor wire 211C, but has higher mechanical strength (e.g., tensile strength) and rigidity.

[0035] The seven conductor wires 211 are positioned at each vertex of a regular hexagon and at the center of the hexagon. These seven conductor wires 211 are twisted together into a single wire. In other words, the internal conductor 21 is formed by twisting together the seven conductor wires 211 in a close-packed structure in its cross-section. In this case, the thickness of the internal conductor 21 is a maximum of 30 μm. By twisting multiple conductor wires 211 loosely or moderately in this way, loosening in the opposite direction to the twist is allowed, giving the linear sensor 2 flexibility.

[0036] The diameter of the conductor wire 211 is not limited to 10 μm, but may be between 8 μm and 40 μm, and preferably between 8 μm and 30 μm. The thinner the conductor wire 211, the greater its flexibility but the lower its strength and rigidity, while the thicker the conductor wire, the less flexible it is but the higher its strength and rigidity. Furthermore, if the conductor wire 211 is 20 μm or thicker, it can be manufactured at low cost and is easy to manufacture. In addition, the inner conductor 21 may be formed by twisting together conductor wires 211 of different thicknesses.

[0037] The internal conductor 21 shown in Figure 1 is made by twisting together seven conductor wires 211, but the number does not have to be seven. By twisting together multiple conductor wires 211, the flexibility of the linear sensor 2 can be increased. Alternatively, the twisting process can be carried out in multiple stages, for example, by preparing multiple bundles of twisted wires and then twisting these bundles together again. For example, seven bundles of seven thin conductor wires 211 twisted together can be prepared and these bundles can be twisted together again. By twisting in multiple stages, the flexibility of the linear sensor 2 is further increased, making it easier for the linear sensor 2 to deform in response to vibrations applied to it. As a result, the detection sensitivity of the linear sensor 2 can be increased. Note that when there are multiple twisting steps, such as when twisting in multiple stages, the direction of twisting can be varied. On the other hand, it is also possible to use bundles of multiple conductor wires 211 that are not twisted together but are arranged in a straight line. Furthermore, these configurations may be combined, for example, by twisting together a bundle of multiple untwisted conductor wires 211 with multiple twisted conductor wires 211. Even in these cases, by applying a piezoelectric material, the multiple conductor wires 211 can be bonded and bundled together to produce a single piezoelectric fiber.

[0038] In the sensor wire 20 described above, multiple types of conductor wires with different mechanical strengths and electrical resistances are used as the conductor wires 211 that constitute the internal conductor 21. However, to further increase flexibility or further decrease electrical resistance, the central conductor wire 211 may be replaced with a copper conductor wire 211C, or all seven conductor wires 211 may be made of copper conductor wires 211C. Conversely, to further increase mechanical strength and rigidity, all seven conductor wires 211 may be made of stainless steel conductor wires 211S. Alternatively, instead of stainless steel conductor wires 211S, tungsten conductor wires, high-tensile steel materials such as tungsten and its alloys, or ultra-high-tensile steel may be used, or instead of copper conductor wires 211C, titanium conductor wires, titanium alloys, or conductor wires made of magnesium or magnesium alloys may be used. Furthermore, conductor wires containing carbon nanotubes may be used, or conductor wires containing pitch-based carbon fibers may be used. Alternatively, conductor wires made of spring steel that is easily elastically deformable may be used.

[0039] The piezoelectric element 22 is formed by coating the internal conductor 21 with a piezoelectric material such as polyvinylidene fluoride (PVDF). Polyvinylidene fluoride is a lightweight polymer material that exhibits a piezoelectric effect, and it has the property of generating a voltage when pressure is applied and generating strain when a voltage is applied. The piezoelectric element 22 is subjected to polarization treatment, and when deformation occurs in the piezoelectric element 22 due to vibration or the like, a voltage is induced between the internal conductor 21 and the external conductor 23.

[0040] As for the piezoelectric material constituting the piezoelectric body 22 shown in Figure 1, in addition to polyvinylidene fluoride, other examples include trifluoroethylene (TrEF), mixed crystal materials of PVDF and TrEF, and polymer materials with dipole moments such as polylactic acid, polyuric acid, and polyamino acids. Furthermore, the piezoelectric material may be applied by dipping (dip coating), spray coating, brush coating, or application using a coating device such as a coater. Note that the configuration is not limited to coating; for example, a configuration in which a strip-shaped PVDF film is spirally wound around the internal conductor 21 may also be used.

[0041] The thickness of the piezoelectric element 22 is preferably greater than or equal to the diameter of the conductor wire 211. The thickness of the piezoelectric element 22 shown in Figure 1 is 10 μm at its thinnest point, but it is preferably between 10 μm and 50 μm. While a thicker piezoelectric element 22 generally results in better detection sensitivity, the limit of its thickness depends on the viscosity of the piezoelectric material and the application method. Furthermore, if the piezoelectric element 22 is too thick, the linear sensor 2 becomes too rigid and lacks flexibility.

[0042] In the internal conductor 21 shown in Figure 1, multiple conductor wires 211 are twisted together, resulting in depressions at the boundaries between the conductor wires 211. These depressions can support more piezoelectric material, increasing the volume (thickness) of the piezoelectric material and thus improving detection sensitivity compared to other areas. The internal conductor 21 has six areas where the piezoelectric material is thicker than in other areas, evenly spaced in the circumferential direction, which contributes to its function as a highly sensitive piezoelectric fiber regardless of the direction in which it is bent.

[0043] In Figure 1, adjacent conductor wires 211 are almost touching each other, but the piezoelectric material penetrates through a small gap by capillary action, filling the gap between adjacent conductor wires 211 (the inside of the internal conductor 21). However, depending on the viscosity and application method of the piezoelectric material, the piezoelectric material may not penetrate the gap between adjacent conductor wires 211. Even in this case, it is sufficient that the piezoelectric material is supported on the outer surface of the internal conductor 21. In the configuration where the strip-shaped PVDF film described above is used as the piezoelectric body 22, the linear sensor 2 will not have the piezoelectric material penetrated into the gap between adjacent conductor wires 211. In this linear sensor 2, the flexibility of the linear sensor 2 is increased compared to the one in which the piezoelectric material penetrates into the gap between adjacent conductor wires 211, thus increasing the detection sensitivity of the linear sensor 2.

[0044] The outer conductor 23 shown in Figure 1 is formed by coating the outer circumference of the piezoelectric body 22 with a polymer conductive material containing carbon, such as carbon nanotubes. The conductive material forming the outer conductor 23 may be a polymer conductive material containing silver fine particles or silver paste. The method of applying this conductive material may be dipping (dip coating), spray coating, brush coating, or coating with a coating device such as a coater. The thickness of the outer conductor 23 is preferably less than or equal to the diameter of the conductor wire 211, and also preferably less than or equal to the thickness of the piezoelectric body 22. The thickness of the outer conductor 23 shown in Figure 1 is 5 μm, but it is preferably between 5 μm and 50 μm. Alternatively, a conductor wire may be used instead of a conductive material for the outer conductor 23.

[0045] The inner sheath 24 covers the outer circumference of the outer conductor 23 to enhance abrasion resistance, chemical resistance, and corrosion resistance. This inner sheath 24 is formed to a thickness of 6 μm. The inner sheath 24 is made of a softer material than the outer sheath 26. This inner sheath 24 is formed by coating it with a polyamide synthetic resin, but it may also be formed by coating it with a polyvinyl chloride resin.

[0046] The shielding coating 25 is a shield made by braiding thin metal wires, such as nickel-plated copper or stainless steel, into a tubular shape. The shielding coating 25 may also be formed by vapor deposition of copper, aluminum, or the like onto an inner sheath 24, which has an inner conductor 21, a piezoelectric element 22, and an outer conductor 23 inside. Alternatively, the shielding coating 25 may be attached to the inner sheath 24 using other methods such as sputtering, EBD (electron beam deposition), CVD (vapor deposition), coating, dipping (dip galvanizing), electroless plating, or adhesive bonding, or it may be formed by wrapping metal foil around it.

[0047] The outer sheath 26 is made of a material with higher abrasion resistance than the inner sheath 24. This outer sheath 26 is formed by coating it with polytetrafluoroethylene (PTFE). However, it may also be formed by coating it with tetrafluoroethylene-hexafluoropropylene fluororesin (FEP), tetrafluoroethylene-ethylene copolymer (EPFE), or tetrafluoroethylene-perfluoroalkoxyethylene copolymer fluororesin (PFA). The coating referred to here may be dipping (dip coating), spray coating, brush coating, or coating with a coating device such as a coater. Furthermore, it is preferable to coat it multiple times to account for the occurrence of pinholes. In addition, the outer sheath 26 may be thicker than the inner sheath 24. Moreover, while the inner sheath 24 may be made of a flammable material, it is preferable that the outer sheath 26 be made of a flame-retardant, non-flammable, or fire-resistant material.

[0048] The diameter of the linear sensor 2 shown in Figure 1 is 0.1 mm. However, the diameter of the linear sensor 2 may be thicker or thinner, preferably between 0.1 and 3.0 mm.

[0049] One end of the linear sensor 2 is connected to a signal cable 28 (see Figure 3). Hereinafter, the end connected to the signal cable 28 may be referred to as the rear end of the linear sensor 2. The signal cable 28 contains a signal wire, a signal ground wire, and an earth wire. The inner conductor 21 is connected to the signal wire in the signal cable 28, the outer conductor 23 is connected to the signal ground wire in the signal cable 28, and the shielding 25 is connected to the earth wire in the signal cable 28. The signal cable 28 is for transmitting the signal obtained by the linear sensor 2 to a measuring device or the like (not shown). The linear sensor assembly is composed of the linear sensor 2 and the signal cable 28.

[0050] Figure 2 shows an example of an insulating and conductive member being attached to the end of a linear sensor that is not connected to the signal cable. Hereinafter, the end not connected to the signal cable 28 may be referred to as the tip of the linear sensor 2. Insulating members 291 and 293, conductive members 292 and 294, and a cover member 295 are attached to the tip of the linear sensor 2. To make the structure easier to understand, this figure shows the attachment state of each member in stages from Figure 2(A) to (F). Note that in Figure 2(A), the internal conductor 21 is shown as a single cylindrical unit.

[0051] Figure 2(A) shows the tip of the linear sensor 2 with the internal conductor 21, external conductor 23, and shielding 25 exposed. Figure 2(B) shows the internal conductor 21 and piezoelectric element 22 covered by the insulating member 291, as shown in Figure 2(A). In this example, since the insulating member 291 covers up to the piezoelectric element 22, the internal conductor 21 can be reliably insulated from the external conductor 23 and shielding 25. Note that in Figure 2(B), a portion of the piezoelectric element 22 is shown exposed to make it easier to understand the positional relationship of each component, but the piezoelectric element 22 may be completely covered by the insulating member 291.

[0052] Figure 2(C) shows the state from that shown in Figure 2(B) to the point where the insulating member 291 and the outer conductor 23 are covered by the conductor member 292. In this example, the potential of the outer conductor 23 and the conductor member 292 are the same. This conductor member 292 makes the inner conductor 21 less susceptible to external noise. Note that in Figure 2(C), a portion of the outer conductor 23 is shown exposed to make it easier to understand the positional relationship of each member, but the outer conductor 23 may be completely covered by the conductor member 292.

[0053] Figure 2(D) shows the state from that shown in Figure 2(C) to the point where the conductor member 292 and the inner sheath 24 are covered by the insulating member 293. In this example, the insulating member 293 covers up to the inner sheath 24, ensuring that the outer conductor 23 is reliably insulated from other conductors. Note that in Figure 2(D), a portion of the inner sheath 24 is shown exposed to make it easier to understand the positional relationship of each member, but the inner sheath 24 may be completely covered by the insulating member 293.

[0054] Figure 2(E) shows the state from that shown in Figure 2(D) to the point where the insulating member 293 and the shielding cover 25 are covered by the conductor member 294. In this example, the potential of the shielding cover 25 and the conductor member 294 are the same. The conductor member 294 shields the internal conductor 21 and the external conductor 23, making them less susceptible to external noise. In Figure 2(E), a portion of the shielding cover 25 is shown exposed to make it easier to understand the positional relationship of each component, but the shielding cover 25 may be completely covered by the conductor member 294.

[0055] Figure 2(F) shows the state shown in Figure 2(E), where the conductor member 294 and the outer sheath 26 are covered with the cover member 295 (made of the same material as the outer sheath 26). In this example, the tip of the linear sensor 2, which is provided with insulating members 291 and 293 and conductor members 292 and 294, can be protected. Alternatively, the cover member 295 may be made of a heat-shrinkable (or heat-sealable) material and heated to create a tight seal over the tip of the linear sensor 2.

[0056] The insulating members 291 and 293 can be made of insulating material (e.g., polyvinyl chloride, polyethylene, etc.). The conductive members 292 and 294 can be made of conductive material (e.g., aluminum, copper, tin, or an alloy of multiple materials, etc.). The shape of the conductive members 292 and 294 is not limited to film or mesh shapes, and cylindrical rod terminals may also be used.

[0057] Furthermore, the insulating members 291, 293, conductor members 292, 294, and cover member 295 do not all need to be used; for example, only the cover member 295 may be used, or the conductor member 292 may be omitted. Also, the configuration is not limited to the above example. For example, if the end faces excluding the outer sheath 26 are cut so that they are on the same plane, the tip portion excluding the outer sheath 26 may be covered with an insulating member, the conductor member may be covered on top of that so as to be in contact with the shield covering 25, and then a cover member may be provided. Alternatively, the inner conductor 21, piezoelectric body 22, outer conductor 23, and inner sheath 24 may be cut shorter than the shield covering 25, insulated, wrapped in the shield covering 25, and then a cover member may be provided. In other words, any configuration that more reliably provides insulation and shielding between conductors is acceptable, and the configuration is not limited.

[0058] Figure 3(a) is a plan view of the sensor unit of this embodiment, and Figure 3(b) is a cross-sectional view of AA in Figure 3(a).

[0059] As shown in Figure 3(b), the sensor unit 1 comprises a linear sensor assembly consisting of the linear sensor 2 and signal cable 28 described above, a base 3, a cover 4, and a peripheral wall 5. The base 3 has a stainless steel structure in which a base 31 and a columnar portion 32 protruding from the base 31 are integrally formed, and a first pressing body 33. The base 31 and columnar portion 32 may be made of other metals such as aluminum or brass, or of resin such as engineering plastic, or of ceramic. It is preferable that the base 31 and columnar portion 32 be made of a highly rigid material to facilitate vibration transmission. The base 31 is an annular shape made of stainless steel with an outer diameter of 20 mm and a thickness (height) of 2 mm. The columnar portion 32 is cylindrical with an outer diameter of 9 mm and a height of 8 mm. A through-hole 3a is formed in the base portion 31 and the central portion of the columnar portion 32, along the protruding direction of the columnar portion 32, and passing through both the base portion 31 and the columnar portion 32. The diameter of the through-hole 3a is 6 mm. However, these shapes are appropriately set according to the equipment to be measured in which this sensor unit 1 is used. For example, the columnar portion 32 may be a shape other than a cylinder, such as a rectangular prism or an elliptical prism, and its cross-sectional shape may change depending on the protruding height, such as tapering towards the protruding direction.

[0060] The first pressing body 33 is a rubber ring with a right-angled triangular cross-section, located at the base of the columnar portion 32, and positioned between the lid 4 and the base portion 31. The rubber material of the first pressing body 33 is a hard synthetic rubber with a compound. The inner diameter of the first pressing body 33 is formed to be slightly smaller than the outer diameter of the columnar portion 32. The two sides of the cross-section of the first pressing body 33 that enclose the right angle are in contact with the base portion 31 and the columnar portion 32, respectively. The hypotenuse of the cross-section of the first pressing body 33 is inclined at approximately 45 degrees with respect to the protruding direction of the columnar portion 32. This protruding direction of the columnar portion 32 coincides with the clamping direction in which the lid 4 clamps the linear sensor 2 between itself and the base portion 31. That is, the hypotenuse of the cross-section of the first pressing body 33 is inclined at approximately 45 degrees with respect to the clamping direction of the lid 4. This hypotenuse forms an inclined surface on the first pressing body 33. The angle of the hypotenuse in the cross-section of the first pressing body 33 does not have to be 45 degrees, but it is preferably 25 degrees or more and 75 degrees or less, and more preferably 30 degrees or more and 70 degrees or less. However, the first pressing body 33 does not necessarily have to be inclined, and may have a surface extending perpendicular to the clamping direction on the linear sensor 2 side.

[0061] The cover 4 sandwiches the linear sensor 2, which is wrapped around the columnar portion 32, between itself and the base 31 via the first pressing body 33. This sandwiching by the cover 4 pushes the linear sensor 2 toward the base 31. As the linear sensor 2 is pressed against the inclined surface of the first pressing body 33, a load is generated on the linear sensor 2 directed laterally (radially toward the columnar portion 32). The first pressing body 33 may, for example, have a fan shape with a hypotenuse in its cross-sectional shape being arc-shaped. In the case of a fan shape, the tangential direction of the arc in the cross-sectional shape is inclined with respect to the sandwiching direction of the cover 4, so the surface formed by that arc becomes an inclined surface. This inclined surface generates a load on the linear sensor 2 directed laterally toward the columnar portion 32. This load is strengthened because the first pressing body 33 has an inclined surface, but even if there is no inclined surface, since the cross-sectional shape of the linear sensor 2 is circular, a load is generated on the linear sensor 2 to some extent towards the side of the columnar portion 32 and towards the columnar portion 32.

[0062] The first pressing body 33 may be made of natural rubber, fluororesin such as PTFE, PFA, ETFE, FEP, PVDF, high-density polyethylene (HDPE), ABS, polyamide, or polyimide. It may also be made of a resin to which compounds or glass fibers have been added. Furthermore, the first pressing body 33 may be made of foam. Since the first pressing body 33 is the part that directly contacts the linear sensor 2 and sandwiches the linear sensor 2 between itself and the lid 4, it is preferable that it is made of a material that is at least more elastically deformable than the base 31. That is, it is preferable that it is made of a material with lower rigidity than the base 31. However, it is preferable that the first pressing body 33 has a certain degree of rigidity so that pressure is applied to the linear sensor 2 sandwiched between the base 31 and the lid 4 to the extent that it undergoes slight deformation in cross-section. In addition, the first pressing body 33 may be made of the same material as the base 31 or the columnar part 32, or it may be formed integrally with the base 31 or the columnar part 32. The first pressing body 33 may be made of metal, but in that case, it is preferable to provide a layer of resin or rubber on the surface of the contact surface with the linear sensor 2 in order to prevent damage to the linear sensor 2.

[0063] The linear sensor 2 is wrapped around the columnar portion 32 multiple times. In this embodiment, the linear sensor 2 is wrapped around the columnar portion 32 from its base to its protruding end, overlapping twice on the outside of the columnar portion 32. That is, the linear sensor 2 makes two turns around the columnar portion 32 at the same height. Note that if the number of turns the linear sensor 2 is wrapped around the columnar portion 32 is less than one, a large directivity may occur in the detection direction, so it is preferable to wrap it at least once. Also, the number of turns the linear sensor 2 is wrapped around the columnar portion 32 may be one, but since the sensitivity of the linear sensor 2 increases in proportion to the number of turns and the output signal also increases, it is preferable to wrap the linear sensor 2 at least two times. As shown in Figure 3(a), an exit hole 5h is formed in the peripheral wall portion 5 for pulling out the rear end of the linear sensor 2. In this embodiment, the connection portion 2b between the linear sensor 2 and the signal cable 28 is located inside the exit hole 5h. Therefore, the lead-out hole 5h corresponds to an example of a guide that guides the rear end of the linear sensor 2 or the signal cable 28 to the outside of the peripheral wall portion 5. The connection portion 2b between the linear sensor 2 and the signal cable 28 may be located outside the peripheral wall portion 5, or it may be located in the portion wrapped around the columnar portion 32.

[0064] As shown in Figure 3(b), the lid 4 has a lid portion 40 and a second pressing body 41. The lid 4 is positioned opposite the base portion 31. The lid portion 40 is made of a stainless steel structure formed integrally with the peripheral wall portion 5. The lid portion 40 and the peripheral wall portion 5 may be made of other metals such as aluminum or brass, or of resin such as engineering plastic, or of ceramic. The lid portion 40 has an annular shape with an outer diameter the same as the base portion 31 and a lid through-hole 40a with the same diameter as the base through-hole 3a formed in the center. The peripheral wall portion 5 has an outer diameter the same as the lid portion 40 and is a hollow cylindrical shape with an inner diameter larger than the lid through-hole 40a. The aforementioned extraction hole 5h penetrates the inner and outer surfaces of this peripheral wall portion 5 in a straight line. The inner diameter of the peripheral wall portion 5 is formed to be approximately 0.4 mm larger than the outer diameter of the columnar portion 32. The linear sensor 2 is housed between the columnar portion 32 and the peripheral wall portion 5, slightly compressed. Therefore, the peripheral wall portion 5 surrounds the linear sensor 2 from the side of the columnar portion 32, in contact with the linear sensor 2 wrapped around the columnar portion 32. The difference between the outer diameter of the columnar portion 32 and the inner diameter of the peripheral wall portion 5 is set appropriately according to the thickness of the linear sensor 2 and the number of times it is wrapped around the columnar portion 32. The height of the peripheral wall portion 5 matches the protruding length of the columnar portion 32. The linear sensor 2 wrapped around the columnar portion 32 is sandwiched between the lid portion 40 and the base portion 31. The lid portion 4 is fixed to the base portion 3 with adhesive while static pressure is applied to the linear sensor 2 wrapped around the columnar portion 32. In other words, the base portion 3, the lid portion 4, and the peripheral wall portion 5 form a storage space for housing the linear sensor 2, and the lid portion 4 covers the linear sensor 2 housed in that storage space while compressing it. The lid 4 and the peripheral wall portion 5 may be fixed to the base 3 by crimping or screwing.

[0065] The second pressing body 41 is a rubber ring with a right-angled triangular cross-section, positioned between the lid portion 40 and the base portion 31. The rubber material of the second pressing body 41 is a hard synthetic rubber containing a compound. The outer diameter of the second pressing body 41 is formed to be slightly larger than the inner diameter of the peripheral wall portion 5. The two sides of the cross-section of the second pressing body 41 that enclose the right angle are in contact with the lid portion 40 and the peripheral wall portion 5, respectively. The hypotenuse in the cross-section of the second pressing body 41 is inclined at approximately 45 degrees with respect to the clamping direction of the lid portion 40. This hypotenuse forms an inclined surface on the second pressing body 41. The angle of the hypotenuse in the cross-section of the second pressing body 41 does not have to be 45 degrees, but it is preferably between 25 degrees and 75 degrees, and more preferably between 30 degrees and 70 degrees. However, the second pressing body 41 does not necessarily have to be inclined, and may have a surface extending perpendicular to the clamping direction on the linear sensor 2 side.

[0066] The lid 4, by clamping the linear sensor 2 wrapped around the columnar portion 32 between itself and the base 31 using the second pressing body 41, generates a load on the linear sensor 2 not only toward the base 31, which is the clamping direction, but also toward the columnar portion 32. This load is strengthened if the second pressing body 41 has an inclined surface, but even if there is no inclined surface, the linear sensor 2 has a circular cross-sectional shape, so a load is generated on the linear sensor 2 to some extent toward the side of the columnar portion 32 and toward the columnar portion 32. The cross-sectional shape of the second pressing body 41 may be, for example, a fan shape with an arc-shaped hypotenuse. In the case of a fan shape, the tangential direction of the arc in the cross-section is inclined with respect to the clamping direction of the lid 40, so the surface formed by that arc becomes an inclined surface. This inclined surface generates a load on the linear sensor 2 toward the columnar portion 32.

[0067] The second pressing body 41 may be made of natural rubber, or of a resin such as fluororesin (PTFE, PFA, ETFE, FEP, PVDF), high-density polyethylene (HDPE), ABS, polyamide, or polyimide. It may also be made of a resin to which compounds or glass fibers have been added. Furthermore, the second pressing body 41 may be made of foam. Since the second pressing body 41 is the part that directly contacts the linear sensor 2 and sandwiches the linear sensor 2 between itself and the base 31, it is preferable that it is made of a material that is at least more elastically deformable than the base 31. That is, it is preferable that it is made of a material with lower rigidity than the base 31. However, it is preferable that the second pressing body 41 has a certain degree of rigidity so that pressure is applied to the linear sensor 2 sandwiched between the base 31 and the lid 4 to the extent that it undergoes slight deformation in cross-section. In addition, the second pressing body 41 may be made of the same material as the lid 4, or it may be formed integrally with the lid 4. The second pressing body 41 may be made of metal, but in that case, it is preferable to provide a layer of resin or rubber on the contact surface with the linear sensor 2 in order to prevent damage to the linear sensor 2.

[0068] Next, we will explain the assembly procedure for sensor unit 1, along with the detailed structure of the sensor unit 1.

[0069] Figure 4 is an exploded cross-sectional view of the sensor unit shown in Figure 3(b). This figure can also be considered a cross-sectional view showing the state before the cover 4 is fixed to the base 3.

[0070] In assembling the sensor unit 1, first, the second pressing body 41 is inserted into the inside of the peripheral wall portion 5 until it contacts the lid portion 40. In this embodiment, the second pressing body 41 is made of rubber and has an outer diameter that is slightly larger than the inner diameter of the peripheral wall portion 5, so it is held in place at the position where it contacts the lid portion 40 due to its own elasticity. Next, the first pressing body 33 is fitted into the columnar portion 32 of the base body 3 so that the first pressing body 33 is positioned at the base of the columnar portion 32. In this embodiment, the first pressing body 33 is made of rubber and has an inner diameter that is slightly smaller than the columnar portion 32, so it is held at the base of the columnar portion 32 due to its own elasticity.

[0071] Next, as shown in the enlarged view circled in Figure 4, the double-sided tape W is attached so as to span the inclined surface of the first pressing body 33 and the side surface of the columnar portion 32. The double-sided tape W may be attached to the entire circumference of the side surface of the columnar portion 32, or to a part of that side surface. Then, the tip of the linear sensor 2 is temporarily fixed by attaching it to the double-sided tape W, and the linear sensor 2 is wrapped around the protruding end of the columnar portion 32. Adhesive or adhesive may be used instead of double-sided tape W.

[0072] Next, adhesive is applied to the contact surface of the peripheral wall portion 5 with the base portion 31. Then, the signal cable 28 is inserted into the exit hole 5h and pulled out from the outer surface of the peripheral wall portion 5, while the cover 4 is pressed against the base portion 31 to lightly compress the linear sensor 2, and the cover 4 and base portion 3 are fixed with a jig until the applied adhesive hardens. The assembly of the sensor unit 1 is completed when the adhesive hardens.

[0073] Figure 5 is a diagram showing an example of an installation state in which the sensor unit shown in Figure 3 is attached to the object to be detected using a fixing device.

[0074] As shown in Figure 5, a screw hole 9a is provided at the measurement location of the object to be detected 9. The sensor unit 1 is fixed to the object to be detected 9 by bolts B that pass through the base through hole 3a and the lid through hole 40a and are tightened into the screw hole 9a. The sensor unit 1 is also pressed against the object to be detected 9 by the bolts B. Alternatively, the sensor unit 1 may be fixed to the object to be detected 9 with adhesive or double-sided tape instead of the bolts B, or with other fasteners such as clips.

[0075] In this mounting state, when vibrations generated in the object to be detected 9 reach the sensor unit 1, those vibrations are first transmitted to the base portion 31. In this embodiment, the linear sensor 2 is surrounded by the base portion 31, the columnar portion 32, and the peripheral wall portion 5, and is in contact with them, and is also lightly compressed by the cover portion 40. Therefore, vibrations transmitted from the object to be detected 9 to the base portion 31 are easily transmitted to the linear sensor 2 from the columnar portion 32 and the peripheral wall portion 5. As a result, in addition to vibrations with an amplitude direction in the direction of clamping by the cover portion 40, vibrations with an amplitude direction other than the clamping direction can also be detected with high sensitivity.

[0076] As described above, the sensor unit 1 can detect vibrations generated in the object to be detected 9 with high sensitivity. Furthermore, since the linear sensor 2 is pressed not only against the base 31 but also against the peripheral wall 5 by the first pressing body 33, vibrations applied from the object to be detected 9 to the peripheral wall 5 via the base 31 are easily transmitted to the linear sensor 2. Similarly, since the linear sensor 2 is pressed against the columnar portion 32 by the second pressing body 41, vibrations applied from the object to be detected 9 to the columnar portion 32 via the base 31 are easily transmitted to the linear sensor 2. As a result, vibrations generated in the object to be detected 9 can be detected with even higher sensitivity. In addition, since the first pressing body 33 and the second pressing body 41 are made of rubber, which is an elastic material, damage to the linear sensor 2 sandwiched between the first pressing body 33 and the second pressing body 41 can be suppressed. Furthermore, since the peripheral wall 5 is formed integrally with the cover portion 40, the number of parts in the sensor unit 1 can be reduced. Furthermore, before the cover 4 is attached to the base 3, the sides of the columnar portion 32 are open, making it easy to wrap the linear sensor 2 around the columnar portion 32. This increases the productivity of the sensor unit 1 and allows it to be produced at a low cost.

[0077] Next, the sensor unit 1 of the second embodiment will be described. In the following description, components with the same names as those described so far will be denoted by the same reference numerals used so far, and redundant descriptions may be omitted.

[0078] Figure 6 is a cross-sectional view of the sensor unit according to the second embodiment.

[0079] The sensor unit 1 shown in Figure 6 differs from the sensor unit 1 of the previous embodiment in that the peripheral wall portion 5 is constructed separately from the cover portion 40, the cover portion 4 has a packing 43, and the shapes of the first pressing body 33 and the second pressing body 41. As shown in Figure 6, the peripheral wall portion 5 is hollow cylindrical. In addition, instead of an outlet hole 5h, the peripheral wall portion 5 has a groove 5g formed on the end face on the cover portion 40 side that is slightly wider than the diameter of the linear sensor 2 and the signal cable 28 and slightly deeper than the diameter of the signal cable 28. The connection portion 2b between the linear sensor 2 and the signal cable 28 is located in this groove 5g. That is, this groove 5g corresponds to an example of a guide portion that guides the rear end of the linear sensor 2 or the signal cable 28 to the outside of the peripheral wall portion 5.

[0080] The lid 4 comprises a lid portion 40, a second pressing body 41, and a packing 43. The lid portion 40 is made of an annular stainless steel plate. The packing 43 is disc-shaped with a hole in the center and has the same shape as the lid portion 40 in plan view. This packing 43 is made of an oil-resistant rubber sheet that is slightly thinner than the lid portion 40. This packing 43 is for sealing the gap between the lid portion 40 and the peripheral wall portion 5. The packing 43 may be made of a material other than rubber, as long as it is more easily deformable than the lid portion 40; for example, it may be made of resin. The packing 43 is fixed to the lid portion 40 with adhesive. The side of the packing 43 opposite to the side fixed to the lid portion 40 is bonded to the columnar portion 32 and the peripheral wall portion 5, respectively, with adhesive. The second pressing body 41 is attached between the columnar portion 32 and the peripheral wall portion 5 on the opposite side.

[0081] The second pressing body 41 is a rubber ring with a right-angled triangular cross-section having a right-angled vertex that protrudes toward the base 31. The hypotenuse of the second pressing body 41 in cross-section is attached to the packing 43, and the two sides enclosing the right angle in cross-section are inclined at 45 degrees in opposite directions with respect to the clamping direction of the lid 4. These two sides form an inclined surface on the second pressing body 41. The two sides enclosing the right angle in the cross-section of the second pressing body 41 may be at different angles, and the inclination angle may be other than 45 degrees. However, the inclination angle of each of the two sides with respect to the clamping direction of the lid 4 is preferably 25 degrees or more and 75 degrees or less, and more preferably 30 degrees or more and 70 degrees or less. When the lid 4 clamps the linear sensor 2 between itself and the base 31 using the second pressing body 41, the linear sensor 2 wrapped around the columnar portion 32 is subjected to loads toward the columnar portion 32 and loads toward the peripheral wall portion 5. The cross-sectional shape of the second pressing body 41 may be a fan shape that is convex toward the base portion 31. In the case of a fan shape, the tangential direction of the cross-section will be inclined with respect to the clamping direction of the cover portion 40, except for the vertex of the convex shape, so the surface formed by the parts other than the vertex will be an inclined surface. This inclined surface generates a load on the linear sensor 2 toward the columnar portion 32 side and the peripheral wall portion 5 side.

[0082] The first pressing body 33 is a rubber ring with a right-angled triangular cross-section having a right-angled vertex that protrudes toward the lid portion 40. The hypotenuse of the first pressing body 33 in cross-section is attached to the base portion 31, and the two sides enclosing the right angle in cross-section are inclined at 45 degrees in opposite directions with respect to the clamping direction of the lid portion 40. These two sides form an inclined surface on the second pressing body 41. The two sides enclosing the right angle in the cross-section of the first pressing body 33 may be at different angles, and the inclination angle may be other than 45 degrees. However, the inclination angle of each of the two sides with respect to the clamping direction of the lid 4 is preferably 25 degrees or more and 75 degrees or less, and more preferably 30 degrees or more and 70 degrees or less. When the lid 4 clamps the linear sensor 2 between itself and the base portion 31 using the first pressing body 33, the linear sensor 2 wrapped around the columnar portion 32 is subjected to loads toward the columnar portion 32 and loads toward the peripheral wall portion 5. The cross-sectional shape of the first pressing body 33 may be a fan shape that is convex toward the lid portion 40. In the case of a fan shape, the tangential direction of the cross-section will be inclined with respect to the clamping direction of the lid portion 40, except for the vertex of the convex shape, so the surface formed by the parts other than the vertex will be an inclined surface. This inclined surface generates a load on the linear sensor 2 toward the columnar portion 32 side and the peripheral wall portion 5 side.

[0083] This second embodiment also has the same effects as the previous embodiment. In addition, although the number of parts increases and thus the assembly man-hours increase, the assembly of the sensor unit 1 is made easier in some respects, because instead of inserting the signal cable 28 into the outlet hole 5h and pulling it out from the outer surface of the peripheral wall portion 5, it is only necessary to insert it into a groove formed in the peripheral wall portion 5.

[0084] Next, we will describe the sensor unit 1 of the third embodiment. In describing this third embodiment, we will focus on the differences from the sensor unit 1 of the second embodiment.

[0085] Figure 7 is a cross-sectional view of the sensor unit according to the third embodiment.

[0086] The sensor unit 1 shown in Figure 7 differs from the sensor unit 1 of the second embodiment shown in Figure 6 in that the base portion 31, the columnar portion 32, and the peripheral wall portion 5 are integrally formed. As shown in Figure 7, the base portion 31, the columnar portion 32, and the peripheral wall portion 5 are formed by cutting a circumferential groove into one end face of a hollow cylindrical stainless steel structure.

[0087] In this third embodiment, in addition to the effects of the second embodiment, the number of parts in the sensor unit 1 is reduced, which has the effect of allowing the sensor unit 1 to be produced at a lower cost.

[0088] Next, we will describe the sensor unit 1 of the fourth embodiment. In describing this fourth embodiment, we will focus on the differences from the sensor unit 1 of the previous embodiment shown in Figure 3.

[0089] Figure 8(a) is a plan view of the sensor unit of the fourth embodiment, and Figure 8(b) is a cross-sectional view of BB in Figure 8(a).

[0090] The sensor unit 1 shown in Figures 8(a) and 8(b) differs from the sensor unit 1 shown in Figure 3 in the shape of the lid portion 40, the direction of penetration of the lead-out hole 5h, the presence of a terminal member 7, and the presence of a conductive shield member 8. It also differs from the sensor unit 1 shown in Figure 3 in that the linear sensor 2 is folded back in the middle in the longitudinal direction and wrapped around the columnar portion 32 with the folded portion as the leading edge. As shown in Figures 8(a) and 8(b), a lid recess 401 is formed on the side of the lid portion 40 where the conductive shield member 8 is located. The lead-out hole 5h is formed diagonally from the inner circumferential surface of the peripheral wall portion 5 to the lid recess 401. The lead-out hole 5h may also be a hole formed by connecting a horizontal hole formed horizontally from the inner circumferential surface of the peripheral wall portion 5 and a vertical hole formed vertically from the lid recess 401. Both ends of the linear sensor 2 pass through this lead-out hole 5h.

[0091] The terminal member 7 is located within the lid recess 401. One end of the signal cable 28 is also located in the lid recess 401. Both ends of the linear sensor 2 and one end of the signal cable 28 are connected to the terminal member 7. The terminal member 7 is a printed circuit board on which an amplifier 71 is mounted. This amplifier 71 amplifies the output signal from the linear sensor 2 and sends it to the signal cable 28. The amplifier 71 amplifies the signal voltage to approximately ±5V. This amplifier 71 has a high impedance on the input side, which is the linear sensor 2 side, and a lower impedance on the output side, which is the signal cable 28 side. The input impedance is preferably 10kΩ to 10MΩ. The output impedance is preferably 10Ω to 100kΩ. In this embodiment, the input impedance is set to 1MΩ and the output impedance is set to 200Ω. In this way, the signal input to the amplifier 71 is amplified in both voltage and current before being output from the amplifier 71. In addition to the signal line, signal ground line, and earth line, the signal cable 28 of this fourth embodiment is also provided with a power line for the amplifier 71.

[0092] The terminal member 7 and one end of the signal cable 28 are continuously covered by a shield 72. This shield 72 is formed by molding a film in which an electromagnetic shielding layer is formed between two insulating layers into a box shape that surrounds the terminal member 7 and one end of the signal cable 28. This electromagnetic shielding layer is electrically connected to the ground electrode of the amplifier 71 and is completely electrically insulated from the cover 4, the peripheral wall 5, and the conductive shielding member 8. In this way, the electromagnetic shielding layer of the shield 72 independently covers the terminal member 7, including the amplifier 71, and one end of the signal cable 28, thereby eliminating the influence of external electromagnetic noise. Furthermore, even if the cover 4 or other parts come into contact with the device or component under test and the potential level of the contacted component changes, the electrical operation of the amplifier 71 remains stable. In addition, it is possible to protect the terminal member 7 and one end of the signal cable 28 from potential changes exceeding the rating of the amplifier 71 and surge noise that unexpectedly occurs, as these are located inside the electromagnetic shielding layer of the shield 72.

[0093] The conductive shielding member 8 is attached to the end face of the cover 4 with adhesive. The conductive shielding member 8 is made of stainless steel, has a disc shape with a shielding through-hole 8a in the center, and in plan view has the same shape as the cover 40. The conductive shielding member 8 may be made of other conductive materials such as thin metal sheets or conductive films other than stainless steel. The terminal member 7 is electrically shielded by both the conductive shielding member 8 and the cover 40. Therefore, the intrusion of noise into the terminal member 7 is further suppressed. In addition, the terminal member 7 is also physically shielded by the conductive shielding member 8 and the cover 40, so damage to the terminal member 7 is also suppressed.

[0094] In this fourth embodiment, in addition to the same effects as the sensor unit 1 shown in Figure 3, an amplifier 71 is provided, which relatively reduces the influence of noise on the output signal of the linear sensor 2. In other words, the signal-to-noise ratio (SNR) of the sensor unit 1 can be increased. As a result, a stronger signal can be sent to external measuring instruments, etc., against external electromagnetic noise and other noise, so that a clear output signal can be obtained at the measuring instruments, etc. Furthermore, since the output signal is amplified by the amplifier 71 and the transmission power is also increased, the output signal can be sent to measuring instruments located at even greater distances. In vibration measurement of infrastructure facilities and large-scale factory facilities, it is sometimes necessary to send the output signal over long distances of tens to hundreds of meters, and in such cases, a great advantage can be obtained. Similarly, if the output signal obtained from the linear sensor 2 is digitized by the electronic circuit mounted on the terminal member 7, it becomes even more resistant to noise and long-distance communication becomes possible, resulting in an even greater advantage. When sending the digitized output signal, the signal cable 28 will be a shielded cable using multi-core stranded wires, different from the analog signal transmission cable.

[0095] Next, we will describe the sensor unit 1 of the fifth embodiment. In describing this fifth embodiment, we will focus on the differences from the sensor unit 1 of the second embodiment shown in Figure 6.

[0096] Figure 9 is a cross-sectional view of the sensor unit according to the fifth embodiment.

[0097] The sensor unit 1 shown in Figure 9 differs from the sensor unit shown in Figure 6 in the shape of the peripheral wall portion 5 and the presence of a terminal member 7. It also differs from the sensor unit 1 shown in Figure 3 in that the linear sensor 2 is folded back in the middle in the longitudinal direction and wrapped around the columnar portion 32 with the folded portion as the leading edge. As shown in Figure 9, a peripheral wall recess 51 is formed on the upper surface of the peripheral wall portion 5. A groove 5g is formed from the inner peripheral surface of the peripheral wall portion 5 to the peripheral wall recess 51. The width of the groove 5g is formed to be slightly wider than the width of two linear sensors 2. Both ends of the linear sensor 2 are positioned in this groove 5g.

[0098] The terminal member 7 is located within the peripheral wall recess 51. One end of the signal cable 28 is also located within the peripheral wall recess 51. Both ends of the linear sensor 2 and one end of the signal cable 28 are connected to the terminal member 7. The terminal member 7 is a printed circuit board on which an amplifier 71 is mounted. This amplifier 71 is the same as the one shown in Figure 8, so its description is omitted.

[0099] The terminal member 7 and one end of the signal cable 28 are continuously covered by a shield 72. This shield 72 is formed by molding a film in which an electromagnetic shielding layer is formed between two insulating layers into a box shape that surrounds the terminal member 7 and one end of the signal cable 28. This electromagnetic shielding layer is electrically connected to the ground electrode of the amplifier 71 and is completely electrically insulated from the cover 4 and the peripheral wall 5. In this way, the electromagnetic shielding layer of the shield 72 independently covers the terminal member 7, including the amplifier 71, and one end of the signal cable 28, thereby eliminating the influence of external electromagnetic noise. Furthermore, even if the cover 4 or other parts come into contact with the device or component under test and the potential level of the contacted component changes, the electrical operation of the amplifier 71 remains stable. In addition, the terminal member 7 and one end of the signal cable 28 are protected from potential changes exceeding the rating of the amplifier 71 and surge noise that occurs unexpectedly, as these are located inside the electromagnetic shielding layer of the shield 72. In addition, the terminal member 7 is electrically shielded by the peripheral wall 5 and the cover 40, further suppressing noise from entering the terminal member 7. Furthermore, the terminal member 7 is also physically shielded by the peripheral wall 5 and the cover 40, thus suppressing damage to the terminal member 7.

[0100] In this fifth embodiment, in addition to the same effects as the sensor unit 1 shown in Figure 6, the effects of including an amplifier 71, similar to the sensor unit 1 shown in Figure 8, are also achieved.

[0101] Figure 10 (a) is a bottom view of the sensor unit of the sixth embodiment, and Figure 10(b) is a cross-sectional view of the CC of Figure 10 (a).

[0102] The sensor unit 1 shown in Figures 10(a) and 10(b) differs from the sensor unit 1 shown in Figure 3 in the shape of the base 3, the shape of the cover 4, the shape of the peripheral wall portion 5, the presence of a terminal member 7, and the presence of a conductive shield member 8. As shown in Figures 10(a) and 10(b), the base 3 has a base portion 31 that generally has the outer shape of a hexagonal bolt, a columnar portion 32 that protrudes from the tip of the base portion 31 toward the tip side, and a first pressing body 33. Hereinafter, in the description of this sixth embodiment of the sensor unit, the lower side in Figure 10(b) will be referred to as the tip side, and the upper side in Figure 10(b) will be referred to as the rear end side. The base portion 31 is composed of a base head 311 with a hexagonal outer shape and a base male screw 312 with screw threads formed thereon. A rectangular recess, the base recess 313, is formed on the rear end surface of the base portion 31. The columnar portion 32 has a smaller diameter than the base male screw 312. Therefore, a step is formed between the columnar portion 32 and the base male screw 312. The base body 3 has a through hole (not shown) connecting the base recess 313 to the columnar portion 32. The linear sensor 2 is passed through this through hole.

[0103] The cover 4 has a disc-shaped cover portion 40, a second pressing body 41, and a cover screw portion 42 that protrudes from the cover portion 40 toward the tip. The cover screw portion 42 has a cylindrical shape with screw threads on its outer circumference. This cover screw portion 42 is an example of a screw portion. The protruding direction of the cover screw portion 42 coincides with the protruding direction of the columnar portion 32.

[0104] A female thread 52 is provided at the rear end of the peripheral wall portion 5. A cylindrical hole into which a columnar portion 32 fits is formed at the front end of the peripheral wall portion 5. This female thread 52 is a hollow cylinder with an inner diameter slightly larger than the portion into which the columnar portion 32 fits. The base body 3 is fixed to the peripheral wall portion 5 by screwing the base male thread 312 into the female thread 52. Also, by screwing the base male thread 312 into the female thread 52, the linear sensor 2 is held in place by the base body 31 and the cover body 4 with a certain amount of pressure via the first pressing body 33 and the second pressing body 41. The outer shape of the peripheral wall portion 5 is hexagonal in plan view. The peripheral wall portion 5, the cover body 40 and the cover screw portion 42 are formed integrally, and the overall outer shape of these components is generally that of a hexagonal bolt larger than the base body 3.

[0105] The terminal member 7 is located within the base recess 313. One end of the linear sensor 2 and one end of the signal cable 28 are connected to the terminal member 7. The terminal member 7 is identical to the one shown in Figure 8, so its description is omitted. The shield 72 covering the terminal member 7 and one end of the signal cable 28 is also identical to the one shown in Figure 8, so its description is omitted.

[0106] The conductive shielding member 8 closes the rear end of the base recess 313. The conductive shielding member 8 is a rectangular plate made of stainless steel, slightly larger than the base recess 313. The conductive shielding member 8 is fixed to the rear end of the base recess 313 with adhesive. The conductive shielding member 8 may be made of other conductive materials such as thin metal plates or conductive films other than stainless steel. A U-shaped notch 8b is formed on one side of the conductive shielding member 8. This notch 8b is formed to be slightly wider than the signal cable 28. The signal cable 28 extends outside the sensor unit 1 through the notch 8b. The conductive shielding member 8 and the base 31 further suppress noise from entering the terminal member 7.

[0107] In this sixth embodiment, in addition to the same effects as the sensor unit 1 of the fourth embodiment shown in Figure 8, the sensor unit 1 itself acts as a bolt, thus providing the advantage that the sensor unit 1 can be easily attached to the object to be detected.

[0108] Figure 11(a) is a bottom view of the sensor unit of the seventh embodiment, and Figure 11(b) is a cross-sectional view of Figure 11(a) from the DD side.

[0109] The sensor unit 1 shown in Figures 11(a) and 11(b) differs from the sensor unit 1 shown in Figure 3 in the shape of the base 3, the shape of the cover 4, the shape of the peripheral wall portion 5, and the presence of a terminal member 7. As shown in Figures 11(a) and 11(b), the base 3 has a base portion 31 that is generally shaped like a grub screw, a columnar portion 32 that protrudes from the tip of the base portion 31, and a first pressing body 33. Hereinafter, in the description of this seventh embodiment of the sensor unit, the lower side in Figure 11(b) will be referred to as the tip side, and the upper side in Figure 11(b) will be referred to as the rear end side. A hexagonal hole 314 into which a hexagonal wrench is fitted is formed on the rear end surface of the base portion 31. The outer circumferential surface of the base portion 31 is a male screw with screw threads formed thereon. In addition, a U-shaped groove 31a recessed from the outer circumferential surface toward the center is formed on the base portion 31. This U-shaped channel 31a is formed to be slightly wider than the signal cable 28. The columnar portion 32 protrudes from the base portion 31 toward the tip. The columnar portion 32 has a smaller diameter than the base portion 31. Therefore, a step is formed between the columnar portion 32 and the base portion 31. In addition, a slit 315 is formed in the base body 3 from the base portion 31 to the columnar portion 32. This slit 315 is a bottomed rectangular hole in Figure 11(b), with the front side of the paper open and the back side closed. However, the slit 315 may also be a through hole with both the front and back sides of the paper open.

[0110] The lid 4 has a lid portion 40 and a second pressing body 41. The lid portion 40 is disc-shaped and the tip of the peripheral wall male screw 53, which will be described later, closes the hollow hole of the peripheral wall male screw 53.

[0111] The peripheral wall portion 5 has a small diameter hollow cylindrical shape at the front end and a larger diameter hollow cylindrical shape at the rear end. The rear end of the large diameter portion of the peripheral wall portion 5 has a female peripheral wall thread 52 with screw threads formed on its inner surface. The base portion 31 is screwed into this female peripheral wall thread 52, thereby fixing the base body 3 to the peripheral wall portion 5. The small diameter portion of the peripheral wall portion 5 has a male peripheral wall thread 53 with screw threads formed on its outer surface. Holes are formed in the front end of the large diameter portion of the peripheral wall portion 5 and in the male peripheral wall thread 53. The columnar portion 32 fits into these holes. When the base portion 31 of the base body 3 is screwed into the female peripheral wall thread 52 of the peripheral wall portion 5, the linear sensor 2 is held in place by the base portion 31 and the cover 4 with a certain amount of pressure via the first pressing body 33 and the second pressing body 41. The outer shape of the large diameter portion of the peripheral wall portion 5 is hexagonal in plan view. The peripheral wall portion 5 and the cover portion 40 are formed integrally, and the overall shape of these components is generally that of a hexagonal bolt.

[0112] The terminal member 7 is located inside the slit 315. One end of the linear sensor 2 and one end of the signal cable 28 are connected to the terminal member 7. The linear sensor 2 extends through the open surface of the slit 315 towards the columnar section and is wrapped around the columnar section 32. The terminal member 7 is identical to the one shown in Figure 8, so its description is omitted. The shield 72 covering the terminal member 7 and one end of the signal cable 28 is also identical to the one shown in Figure 8, so its description is omitted. The terminal member 7 is completely enclosed by the base 3 and the peripheral wall 5, which further suppresses noise intrusion. The signal cable 28 extends outside the sensor unit 1 through the U-shaped groove 31a.

[0113] In this seventh embodiment, in addition to the same effects as the sensor unit 1 of the sixth embodiment shown in Figure 10, a part of the linear sensor 2 can be inserted inside the object to be detected, so that the sensor unit 1 can detect vibrations with higher detection sensitivity.

[0114] The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims. For example, although a linear sensor 2 using a piezoelectric body 22 has been described in this embodiment, it may be changed to a linear sensor 2 using a resistance wire or capacitor wire made of conductive rubber or the like. Also, one or both of the first pressing body 33 and the second pressing body 41 may be omitted. Furthermore, the outer shapes of the base 31, columnar part 32 and cover part 40 do not have to be circular in plan view, and may be polygonal, for example. In addition, although an example in which the sensor unit 1 is attached to the object to be detected 9 so that the base 31 contacts the object to be detected 9 has been described, the sensor unit 1 may be attached in the opposite direction to the example shown in Figure 5 so that the cover part 40 contacts the object to be detected 9. Also, the linear sensor 2 may be folded in the middle in the length direction, and the linear sensor 2 may be wrapped around the columnar part 32 with the folded portion at the front. In that case, the insulating members 291, 293, conductor members 292, 294, and cover member 295 at the tip of the linear sensor 2 may be omitted, and both the tip and rear end of the linear sensor 2 may be connected to the signal cable 28. In this case, it is preferable to connect both the internal conductors 21 at the tip and rear end of the linear sensor 2 to the signal lines of the signal cable 28, both the external conductors 23 at the tip and rear end of the linear sensor 2 to the signal ground line of the signal cable 28, and both the shield coverings 25 at the tip and rear end of the linear sensor 2 to the ground wire inside the signal cable 28.

[0115] Furthermore, even if a constituent element is included only in the description of each embodiment or each modification described above, that constituent element may be applied to other embodiments or other modifications. [Explanation of Symbols]

[0116] 1 Sensor Unit 2 Linear Sensors 3 Base 31 Rigid base 32 Columnar part 40 Lid 50 Peripheral wall section

Claims

1. A base having a base portion and a columnar portion protruding from the base portion, A linear sensor, which is wrapped around the columnar portion and detects pressure or vibration, A peripheral wall portion surrounding the linear sensor, in contact with the linear sensor from the side of the columnar portion, It comprises a cover positioned opposite the base and sandwiching the linear sensor between the base and the cover, The substrate has a first pressing body, The sensor unit is characterized in that the cover sandwiches the linear sensor between itself and the base via the first pressing body.

2. The sensor unit according to claim 1, characterized in that the first pressing body is made of a material that is more elastically deformable than the base.

3. The sensor unit according to claim 1 or 2, characterized in that the first pressing body has an inclined surface formed thereon that is inclined with respect to the direction in which the lid is clamped.

4. A base having a base portion and a columnar portion protruding from the base portion, A linear sensor, which is wrapped around the columnar portion and detects pressure or vibration, A peripheral wall portion surrounding the linear sensor, in contact with the linear sensor from the side of the columnar portion, It comprises a cover positioned opposite the base and sandwiching the linear sensor between the base and the cover, The sensor unit is characterized in that the cover has a second pressing body, and the linear sensor is sandwiched between the base and the second pressing body.

5. The sensor unit according to claim 4, characterized in that the second pressing body is made of a material that is more elastically deformable than the base.

6. The sensor unit according to claim 4 or 5, characterized in that the second pressing body has an inclined surface that is inclined with respect to the direction in which the lid is clamped.

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