Load sensor device

Abstract

To provide a load sensor device capable of achieving high accuracy of a detected value and obtaining excellent impact resistance. A load sensor device according to one aspect of the present invention includes a load sensor having a pressure receiving portion, a housing that houses the load sensor, an elastic body that receives a load and presses the load sensor, and a pressing member provided between the elastic body and the load sensor, the pressing member having a rigid pressing portion that can contact the pressure receiving portion and an elastic support portion that supports the rigid pressing portion to the housing, a gap being provided between the rigid pressing portion and the pressure receiving portion in a state where no load is applied to the elastic body, the elastic support portion being elastically deformed to reduce the gap between the rigid pressing portion and the pressure receiving portion when a load is applied to the elastic body, the load sensor device including a buffer portion that can moderate the elastic deformation of the elastic support portion.

Description

Technical Field

[0001] The present invention relates to a load sensor device for sensing a load. Background Art

[0002] In recent years, load sensor devices that sense load have become increasingly common in electronic devices and the like. Patent Document 1 discloses a pressure sensor comprising: a pressure-sensitive element having a pressure-sensitive surface formed with a first electrode and a second electrode, wherein an electrical parameter between the first electrode and the second electrode changes in response to pressure acting on the pressure-sensitive surface; a pressurizing member having electrical conductivity; and a supporting portion that supports the pressurizing member such that one end of the pressurizing member contacts the first electrode of the pressure-sensitive element when a load exceeding a predetermined value is applied to the pressurizing member in the direction of the first electrode of the pressure-sensitive element. The pressure sensor is used to determine whether a load is being applied to the pressurizing member based on the result of measuring the electrical parameter between the pressurizing member and the second electrode of the pressure-sensitive element.

[0003] Patent Document 2 discloses a load detection device comprising a magnetostrictive load sensor that magnetizes a magnetic body by passing an electric current through a coil, applies a load to the magnetic body, changes its magnetic properties, converts the change in magnetic properties into a voltage change, and outputs the result to detect the load. The load detection device is characterized in that the magnetostrictive load sensor or a load detection system including the magnetostrictive load sensor is provided with an overload prevention mechanism comprising an elastic body.

[0004] Patent document 3 discloses a panel switch, which includes: a switch unit, which is constructed by attaching an elastic metal partition concentrically and in contact with a horseshoe-shaped contact using tape, and is composed of a horseshoe-shaped contact formed on an insulating substrate or an insulating sheet and a roughly circular contact adjacent to the inner side thereof; a button, which has a rod on its lower surface for pressing the center portion of the above-mentioned partition; and a shock-absorbing plate, which is sandwiched between the partition of the above-mentioned switch unit and the rod of the button and is formed of silicone rubber or foam material.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-152429

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2001-281074

[0009] Patent Document 3: Japanese Patent No. 2926970

[0010] A load sensor device that senses a load is required to have high sensing accuracy and linearity of a detection value with respect to the load. In addition, it is preferred that the device be resistant to shocks that may be applied during the manufacturing process or use. Summary of the Invention

[0011] The present invention has been made in view of the above-mentioned actual circumstances, and an object of the present invention is to provide a load sensor device that can achieve high accuracy of detection values ​​and obtain excellent impact resistance.

[0012] As a result of the research conducted by the inventors of the present application from the viewpoint of increasing the accuracy of the detection value, they have come to the following conclusion: it is better to make the component (pressing component) that presses the pressure-receiving part of the load sensor when a load is applied not in contact with the pressure-receiving part in a no-load state. However, if it is set to be non-contact in a no-load state like this, it is also obvious that when an impact is received from the outside, the pressing component collides with the pressure-receiving part, and the load sensor may be damaged by the collision. Therefore, as a result of further research, the following new conclusion has been obtained: when the rigid pressing component is displaced toward the pressure-receiving part in a load-applied state, the excessive deformation and deformation speed of the component that elastically supports the rigid pressing component are mitigated, thereby reducing the possibility of the load sensor being damaged when subjected to the above-mentioned impact.

[0013] In one embodiment of the present invention completed based on relevant insights, the load sensor device is characterized in that it comprises: a load sensor having a pressure-receiving part; a shell that accommodates the load sensor; an elastic body that bears the load and presses the load sensor; and a pressing component that is arranged between the elastic body and the load sensor, the pressing component having: a rigid pressing part that can contact the pressure-receiving part; and an elastic supporting body that supports the rigid pressing part on the shell, and a gap is provided between the rigid pressing part and the pressure-receiving part when no load is applied to the elastic body. When a load is applied to the elastic body, the elastic supporting part generates elastic deformation in a manner that reduces the gap between the rigid pressing part and the pressure-receiving part, and the load sensor device has a buffer part that can alleviate the elastic deformation of the elastic supporting part.

[0014] According to this configuration, by providing the pressing member with elasticity, when the elastic body is pressed, a load can be transmitted from the elastic body to the pressure-receiving portion via the elastic supporting portion and the rigid pressing portion. In this load sensor device, when an impact is applied to the pressing member, the buffer portion mitigates the elastic deformation of the elastic supporting portion, thereby reducing the displacement speed of the rigid pressing portion and mitigating the impact force transmitted from the rigid pressing portion to the pressure-receiving portion.

[0015] In the load sensor device described above, the elastic support portion may include a leaf spring portion extending from the rigid pressing portion in a direction intersecting the load application direction. Furthermore, the leaf spring portion may be integrally formed with the rigid pressing portion. In this manner, the elastic support portion includes a leaf spring portion extending from the rigid pressing portion in a direction intersecting the load application direction. This allows for more stable and space-saving support of the rigid pressing portion compared to a coil spring, while also facilitating load transfer to the pressure-receiving portion.

[0016] In the load sensor device, the buffer portion may include a first soft elastic member disposed on a side of the pressing member that is opposite the load sensor. Thus, when an impact is applied to the pressing member, the elastic supporting portion, which is elastically deformed, can contact the first soft elastic member, thereby relieving the elastic deformation of the elastic supporting portion.

[0017] In the load sensor device described above, the first soft elastic member preferably has a first through-hole, and when a load is applied to the elastic body, the rigid pressing portion and the pressure receiving portion can come into contact via the first through-hole. Thus, even if the first soft elastic member is provided on the side of the pressing member opposite the load sensor, when the rigid pressing portion and the pressure receiving portion come into contact, they can directly contact each other via the first through-hole, allowing the load of the pressing member to be transmitted to the pressure receiving portion without intervening through the first soft elastic member.

[0018] In the load sensor device, the buffer portion may include a second soft elastic member disposed on a side of the leaf spring portion that is opposite to the elastic body. Thus, when an impact is applied to the pressing member, the elastic supporting portion that is elastically deformed can contact the second soft elastic member, thereby alleviating the elastic deformation of the elastic supporting portion.

[0019] In the load sensor device described above, the second soft elastic member preferably has a second through-hole, and when a load is applied to the elastic body, the elastic body or a member disposed between the elastic body and the rigid pressing portion and the rigid pressing portion are in contact with each other via the second through-hole. Thus, even if the second soft elastic member is disposed on the side of the leaf spring portion opposite the elastic body, the elastic body or the member disposed between the elastic body and the rigid pressing portion and the rigid pressing portion can still directly contact each other via the second through-hole, enabling load to be transmitted from the elastic body to the pressing member without interposing the second soft elastic member.

[0020] In the load sensor device, the buffer portion may include a portion made of a fluid material having a buffering property within the housing. The portion made of the fluid material can thereby reduce the displacement speed of the rigid pressing portion, thereby alleviating the impact force transmitted from the rigid pressing portion to the pressure receiving portion.

[0021] In the load sensor device, the housing may include a stopper that limits the amount of deformation of the elastic body in the direction of load application when a load is applied to the elastic body. Thus, when an overload is applied to the elastic body, the deformation of the elastic body is limited by the stopper, thereby protecting the load sensor from the overload.

[0022] In the load sensor device, the peripheral edge of the pressing member may be fixed to the housing. Thus, the peripheral edge of the pressing member is supported by the housing and the pressing member can be displaced such that the central portion thereof bends with the peripheral edge of the pressing member serving as a fulcrum.

[0023] In the load sensor device, preferably, when viewed in the load application direction, the rigid pressing portion entirely overlaps with the load-bearing portion of the elastic body, and the pressure-receiving portion entirely overlaps with the rigid pressing portion. Thus, the load borne by the load-bearing portion of the elastic body can be directly applied to the pressure-receiving portion of the load sensor via the rigid pressing portion in the load application direction.

[0024] In the load sensor device described above, the load sensor may include a displacement portion that is displaced by a load applied to a pressure-receiving portion, and a plurality of piezoresistive elements that electrically detect the displacement of the displacement portion. In a load sensor using such a plurality of piezoresistive elements, the balance of detection values ​​obtained by the plurality of piezoresistive elements is easily disrupted when an impact is applied to the pressure-receiving portion. As described above, the elastic deformation of the elastic support portion can be mitigated by the buffer portion, thereby mitigating the impact force transmitted from the rigid pressing portion to the pressure-receiving portion. This makes it easier to maintain the balance of detection values ​​obtained by the plurality of piezoresistive elements even when an impact is applied.

[0025] In the load sensor device, the buffer portion is preferably provided in contact with the elastic support portion, so that when the elastic support portion is elastically deformed, the elastic deformation can be effectively alleviated by the buffer portion.

[0026] In the load sensor device, the buffer portion includes a gel-like resin attached to the elastic support portion. This allows the gel-like resin to effectively mitigate the elastic deformation of the elastic support portion when the elastic support portion is elastically deformed.

[0027] In the load sensor device, a rigid plate portion may be provided between the elastic body and the rigid pressing portion. Providing such a rigid plate portion can suppress loss of load transmitted from the elastic body to the rigid pressing portion, thereby improving measurement accuracy.

[0028] Effects of the Invention

[0029] According to the present invention, it is possible to provide a load sensor device that can achieve high accuracy of detection values ​​and obtain excellent impact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a perspective view illustrating the configuration of the load sensor device according to the first embodiment.

[0031] Figure 2 To illustrate the configuration of the load sensor device according to the first embodiment, Figure 1 Cross-sectional view at line A-A.

[0032] Figure 3 It is an exploded perspective view of the load sensor device according to the first embodiment.

[0033] Figure 4 The figure is a top view showing an example of the displacement portion of the load sensor.

[0034] Figure 5 This is a perspective view illustrating the arrangement of the buffer portion of the load sensor device according to the first embodiment.

[0035] Figure 6 (a) and Figure 6 (b) is a diagram illustrating the operation of the load sensor device according to this embodiment.

[0036] Figure 7 It is an exploded perspective view of a load sensor device according to a second embodiment.

[0037] Figure 8 This is a cross-sectional view illustrating the configuration of a load sensor device according to a second embodiment.

[0038] Figure 9 This is an exploded perspective view of a load sensor device according to a third embodiment.

[0039] Figure 10 It is a cross-sectional view illustrating the configuration of a load sensor device according to a third embodiment.

[0040] Figure 11 It is an exploded perspective view of a load sensor device according to a fourth embodiment.

[0041] Figure 12 It is a cross-sectional view illustrating the configuration of a load sensor device according to a fourth embodiment.

[0042] Figure 13 It is a cross-sectional view illustrating the configuration of a load sensor device according to a fifth embodiment.

[0043] Figure 14 This is a diagram illustrating the results of the load test of Example 1 of the present invention.

[0044] Figure 15 This is a diagram illustrating the results of the load test of Example 2 of the present invention.

[0045] Figure 16 This is a diagram illustrating the results of the load test of Example 3 of the present invention.

[0046] Figure 17 It is a figure which shows the result of the load test of Examples 1-3 of this invention.

[0047] Figure 18 It is a figure which shows the result of the load test of Examples 4-6 of this invention.

[0048] Figure 19 This is a diagram illustrating the results of a load test of a comparative example.

[0049] Figure 20 This is a diagram illustrating the results of a load test of a comparative example.

[0050] Figure 21 It is a figure which shows the result of the load test of Reference Examples 1-2.

[0051] Description of Reference Numerals

[0052] 1, 1B, 1C, 1D, 1E... Load sensor device

[0053] 10...Load sensor

[0054] 11...pressure part

[0055] 12...Sensor substrate

[0056] 13……Base substrate

[0057] 14...die bond resin

[0058] 15...bonding wire

[0059] 20... Shell

[0060] 21...Embo

[0061] 22... Storage

[0062] 23...Steps

[0063] 23a...protrusion

[0064] 25...Hook

[0065] 30... Pressing parts

[0066] 31...Elastomer

[0067] 32... Rigid pressing part

[0068] 33... elastic support part

[0069] 40...frame

[0070] 40h...hole

[0071] 50...buffer

[0072] 51 ... first soft elastic component

[0073] 51h...First through hole

[0074] 52 ... the second soft elastic component

[0075] 52h...Second through hole

[0076] 53...Flowing material part

[0077] 60... Rigid plate

[0078] 61…convex part

[0079] 90...board

[0080] 121...Displacement

[0081] 122……Piezo resistance element

[0082] 311...The Bulge

[0083] 312...flange

[0084] 330...Leaf Spring

[0085] 331...frame

[0086] 331h...Kong

[0087] 332...arm

[0088] 332a...Connection

[0089] R1...Pre-travel area

[0090] R2……Force area

[0091] S1, S2...Itinerary

[0092] d...gap DETAILED DESCRIPTION

[0093] Hereinafter, the embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same reference numerals are given to the same components, and the description of the components previously described will be omitted as appropriate.

[0094] (First embodiment)

[0095] Figure 1 This is a perspective view illustrating the configuration of the load sensor device according to the first embodiment.

[0096] Figure 2 To illustrate the configuration of the load sensor device according to the first embodiment, Figure 1 Cross-sectional view at line A-A.

[0097] Figure 3 It is an exploded perspective view of the load sensor device according to the first embodiment.

[0098] Figure 4 The figure is a top view showing an example of the displacement portion of the load sensor.

[0099] Figure 5 This is a perspective view illustrating the arrangement of the buffer portion of the load sensor device according to the first embodiment.

[0100] The load sensor device 1 of the first embodiment is a device that receives an external load and outputs a signal corresponding to the load. The load sensor device 1 includes a load sensor 10, a housing 20 that houses the load sensor 10, an elastic body 31 that receives the load and presses the load sensor 10, and a pressing member 30 disposed between the elastic body 31 and the load sensor 10. In the description of the embodiment, the normal direction of the surface of the housing 20 on which the load sensor 10 is mounted is referred to as the Z direction, one of the directions orthogonal to the normal direction (Z direction) is referred to as the X direction, and the other of the directions orthogonal to the normal direction (Z direction) is referred to as the Y direction.

[0101] The load sensor 10 includes a pressure-receiving portion 11 and a sensor substrate 12. The pressure-receiving portion 11 protrudes from the upper surface of the sensor substrate 12, for example, in a cylindrical shape, and receives an external load. The pressure-receiving portion 11 is made of a silicon compound or silicon (the same material as the sensor substrate 12).

[0102] The sensor substrate 12 includes a displacement portion 121 that is displaced by the load applied to the pressure-receiving portion 11, and a plurality of piezoresistive elements 122 that electrically detect the displacement of the displacement portion 121. The sensor substrate 12 is bonded to the base substrate 13, for example, by diffusion bonding using Au. The base substrate 13 is connected to the housing 20 via a die-bonding resin 14. The displacement portion 121 is displaced by the load applied to the pressure-receiving portion 11 and is provided on the surface of the sensor substrate 12 opposite the pressure-receiving portion 11.

[0103] The piezoresistive element 122 is an element that electrically detects the amount of displacement of the displacement portion 121. A plurality of piezoresistive elements 122 are provided in the displacement portion 121. The plurality of piezoresistive elements 122 are arranged at a phase difference of 90° (in a position relationship orthogonal to each other) between adjacent elements along the peripheral portion of the displacement portion 121. If the displacement portion 121 is displaced by a load received by the pressure receiving portion 11, the resistance of the plurality of piezoresistive elements 122 changes in accordance with the amount of displacement, the potential at the midpoint of a bridge circuit composed of the plurality of piezoresistive elements 122 changes, and this potential becomes the sensor output.

[0104] The housing 20 is formed, for example, in a box shape, and has a rim portion 21 and a receiving portion 22 as a central recessed portion. The rim portion 21 becomes the uppermost surface of the housing 20, and functions as a stopper that limits the amount of deformation of the elastic body 31 in the direction of application of load (Z direction) when a load from the outside is received.

[0105] The load sensor 10 is received in the receiving portion 22. A pad is provided in the receiving portion 22, and the received load sensor 10 is electrically connected to the pad by a bonding wire 15. Resin (not shown) can be embedded in the receiving portion 22 for the purpose of protecting the bonding wire 15 and the like.

[0106] A stepped portion 23 is provided on the inner side of the rim portion 21 so as to surround the receiving portion 22. The stepped portion 23 supports the buffer portion 50 described later and the rigid pressing portion 32 of the pressing member 30.

[0107] The pressing member 30 has a rigid pressing portion 32 that comes into contact with the pressure receiving portion 11, and an elastic support portion 33 that supports the rigid pressing portion 32 to the housing 20. An elastic body 31 that receives a load from the outside is provided on the pressing member 30. The elastic body 31 has a protruding portion 311 and a flange portion 312. The elastic body 31 is formed of rubber, for example. The protruding portion 311 is provided in a cylindrical shape, for example, and the flange portion 312 has a surface for placing the protruding portion 311 on the rigid pressing portion 32.

[0108] The rigid pressing portion 32 is a plate-shaped member formed of a material harder than the elastic body 31. A stainless steel plate having a thickness of about 0.2 mm is used for the rigid pressing portion 32, for example. As the rigid pressing portion 32, silicon, ceramic, glass, aluminum, or the like can be used. The elastic modulus of the rigid pressing portion 32 is higher than that of the elastic body 31, and is preferably 60 GPa or more.

[0109] Preferably, when viewed in the load application direction (Z direction), the entire rigid pressing portion 32 overlaps with the load-bearing portion of the elastic body 31, and the entire pressure-receiving portion 11 overlaps with the rigid pressing portion 32. Thus, the load received by the load-bearing portion of the elastic body 31 can be directly applied to the pressure-receiving portion 11 of the load sensor 10 in the load application direction via the rigid pressing portion 32.

[0110] The elastic support portion 33 includes a frame portion 331 and an arm portion 332. The elastic support portion 33 is connected to the rigid pressing portion 32 via a connecting portion 332a provided between the arm portion 332 and the rigid pressing portion 32. The frame portion 331 is provided with a positioning hole 331h. The stepped portion 23 of the housing 20 on which the frame portion 331 is placed is provided with a positioning protrusion 23a. When the frame portion 331 is placed on the stepped portion 23, the protrusion 23a engages with the positioning hole 331h, thereby determining the placement position of the elastic support portion 333.

[0111] The arm portion 332 is a leaf spring portion 330 extending from the rigid pressing portion 32 in a direction intersecting the direction in which the load is applied. The rigid pressing portion 32 is supported at a predetermined spring constant by the elastic deformation of the arm portion 332. This spring constant is adjusted not only by the material of the arm portion 332 but also by its width, thickness, length, and shape. For example, the narrower the plate width of the connecting portion 332a, the smaller the spring constant of the arm portion 332 of the elastic supporting portion 33, making it easier to obtain a soft pre-stroke feeling. On the other hand, the wider the plate width of the connecting portion 332a, the larger the spring constant of the arm portion 332, making it easier to obtain a pressing feeling.

[0112] The arm portion 332 is symmetrically arranged in a leaf spring shape with the rigid pressing portion 32 as the center. This facilitates the transmission of the load from the elastic body 31 to the pressure-receiving portion 11 directly below. Furthermore, by supporting the rigid pressing portion 32 with the leaf spring portion 330 (arm portion 332) extending in a direction intersecting the direction of load application, the rigid pressing portion 32 can be supported stably and in a more space-saving manner, compared to a case where the rigid pressing portion 32 is supported by a coil spring extending in the direction of load application. Alternatively, the leaf spring portion 330 may be integrally formed with the rigid pressing portion 32.

[0113] Furthermore, by providing elasticity to the pressing member 30, when the elastic body 31 is pressed, a load can be transmitted from the elastic body 31 to the pressure-receiving portion 11 of the load sensor 10 via the elastic support portion 33 and the rigid pressing portion 32. In this case, the rigid pressing portion 32 in contact with the pressure-receiving portion 11 can be formed of a highly rigid material (such as metal or silicon), thereby suppressing load loss and improving detection sensitivity.

[0114] When a load sensor 10 uses a bridge circuit composed of multiple piezoresistive elements 122 to obtain an output, the convex pressure-receiving portion 11 must bear the load in order to efficiently displace the displaceable portion 121. Therefore, when the load is transferred from the pressing member 30 to the pressure-receiving portion 11, if the rigidity of the components in contact with the pressure-receiving portion 11 is low, the load cannot be effectively transferred to the pressure-receiving portion 11. In this embodiment, since the rigid pressing member 32 presses the pressure-receiving portion 11, the loss of external load can be suppressed, allowing for efficient load transfer to the pressure-receiving portion 11.

[0115] In the load sensor device 1, when no load (including impact) is applied to the elastic body 31 (unloaded state), a gap d is provided between the rigid pressing portion 32 and the pressure receiving portion 11. When a load is applied to the elastic body 31, the elastic support portion 33 elastically deforms to reduce the gap d between the rigid pressing portion 32 and the pressure receiving portion 11. The rigid pressing portion 32 then contacts the pressure receiving portion 11, thereby transmitting the load applied to the elastic body 31 to the load sensor 10.

[0116] Such a load sensor device 1 is provided with a buffer portion 50 that can mitigate the elastic deformation of the elastic support portion 33. The buffer portion 50 serves to reduce the displacement speed of the rigid pressing portion 32 when the rigid pressing portion 32 is displaced by the elastic deformation of the elastic support portion 33.

[0117] The buffer portion 50 includes a first soft elastic member 51 disposed on the side of the pressing member 30 facing the load sensor 10. The first soft elastic member 51 is made of a shock absorbing material having a large loss tangent (tan δ) as a dynamic viscoelastic property, such as silicone, synthetic rubber, urethane, or a gel-like resin.

[0118] The first soft elastic member 51 may be arranged to always be in contact with the elastic support portion 33, or may be arranged to be in contact with the elastic support portion 33 when the elastic support portion 33 is elastically deformed. Thus, when an impact is applied to the pressing member 30, the elastically deformed elastic support portion 33 contacts the first soft elastic member 51 to mitigate the elastic deformation of the elastic support portion 33, thereby reducing the displacement speed of the rigid pressing portion 32.

[0119] The first soft elastic component 51 has a first through-hole 51h. Thus, when a load is applied to the elastic body 31, the rigid pressing portion 32 and the pressure-receiving portion 11 can contact each other via the first through-hole 51h. That is, even if the first soft elastic component 51 is provided on the side of the pressing component 30 opposite the load sensor 10, when the rigid pressing portion 32 contacts the pressure-receiving portion 11, the two can still directly contact each other via the first through-hole 51h, allowing the load of the pressing component 30 to be transmitted to the pressure-receiving portion 11 without the first soft elastic component 51 intervening.

[0120] In the load sensor device 1 of this embodiment, when an impact is applied to the pressing member 30, the buffer portion 50 can reduce the displacement speed of the rigid pressing portion 32, thereby mitigating the impact load applied to the pressure-receiving portion 11 of the load sensor 10. This improves the load resistance of the load sensor 10. Furthermore, when a normal load is applied, the rigid pressing portion 32 and the pressure-receiving portion 11 can directly contact each other via the first through-hole 51h, effectively transmitting the load to the pressure-receiving portion 11 and enabling highly accurate load detection.

[0121] (Assembly of the load cell device)

[0122] In the above configuration, the load sensor 10 is housed in the housing portion 22 of the housing 20, and the load sensor 10 is connected to the pads of the housing portion 22 via bonding wires 15. A sheet-like first soft elastic member 51, serving as a buffer portion 50, is disposed on the stepped portion 23 of the housing portion 22. The first through-hole 51h of the first soft elastic member 51 is positioned so as to overlap with the pressure receiving portion 11 when viewed in the Z direction. The pressing member 30 is placed on top of the first soft elastic member 51. Furthermore, the elastic body 31 is placed on top of the rigid pressing portion 32.

[0123] Then, in this state, the frame 40 is placed over the housing 20. The frame 40 is secured by hooking onto the hook 25 provided on the side of the housing 20. A hole 40h is provided in the center of the frame 40. When the frame 40 is placed over the housing 20, the protrusion 311 protrudes upward from the hole 40h. The elastic body 31 is pressed against the frame 40 at the flange 312. This secures the pressing member 30 to the housing 20.

[0124] In the load sensor device 1 assembled in this manner, a gap d is provided between the rigid pressing portion 32 and the pressure receiving portion 11 when no load is applied to the pressing member 30. In other words, the surface of the rigid pressing portion 32 on the pressure receiving portion 11 side does not contact the pressure receiving portion 11. The presence of gap d between the rigid pressing portion 32 and the pressure receiving portion 11 allows for adjustment of assembly tolerances.

[0125] That is, if the rigid pressing portion 32 comes into contact with the pressure receiving portion 11 or comes close to contact, the two may collide due to dimensional errors, misalignment during assembly, etc. If a highly rigid component such as the rigid pressing portion 32 collides with the pressure receiving portion 11, it may adversely affect the load sensor 10. By providing a gap d between the rigid pressing portion 32 and the pressure receiving portion 11, as in this embodiment, collisions during assembly can be actively avoided, thereby protecting the load sensor 10.

[0126] (Operation of the load cell device)

[0127] Figure 6 (a) and Figure 6 (b) is a diagram illustrating the operation of the load sensor device according to this embodiment. Figure 6 (a) is a diagram showing an example of a state where a load is applied to the load sensor device 1. Figure 6 (b) shows an example of the output of the load cell. Figure 6 In (b), the horizontal axis (stroke) represents the stroke of the plate 90 in the Z direction, and the vertical axis (detected force value) represents the output value (relative value).

[0128] like Figure 6 As shown in (a), a load is applied to the elastic body 31 of the pressing member 30 of the load sensor device 1 via the plate 90. When the load is applied to the elastic body 31 in the Z direction from the plate 90, the rigid pressing portion 32 supported by the spring action of the elastic supporting portion 33 is pressed in the Z direction.

[0129] Here, since a gap d is provided between the rigid pressing portion 32 and the pressure receiving portion 11 of the load sensor 10 , no load is applied to the pressure receiving portion 11 until the rigid pressing portion 32 and the pressure receiving portion 11 come into contact.

[0130] Therefore, if Figure 6 As shown in (b), no output is generated from the time a load is applied to the load sensor device 1 until the specified stroke S1. This region is referred to as the pre-stroke region R1. In the pre-stroke region R1, when a load is applied, the elastic support portion 33 elastically deforms. While the pressing member 30 generates a stroke until the rigid pressing portion 32 contacts the pressure-receiving portion 11, the load is not transmitted to the pressure-receiving portion 11, and the output value does not increase. The length of the pre-stroke region R1 can be set based on the gap d. Furthermore, the load required for the pre-stroke can be set based on the spring constant of the elastic support portion 33.

[0131] Next, if a load is applied beyond the pre-stroke region Rl, the output value increases in accordance with the stroke. This region is referred to as a force region R2. Since the rigid pressing portion 32 is in contact with the pressure receiving portion 11 in the force region R2, the load is transmitted from the elastic body 31 to the pressure receiving portion 11 via the rigid pressing portion 32. Due to the rigidity of the rigid pressing portion 32 in contact with the pressure receiving portion 11, the output value from the load sensor 10 increases in a manner substantially proportional to the magnitude of the stroke (load). The output value increases in accordance with the stroke up to Vl.

[0132] The force region R2 continues to the position where the rim portion 21 of the housing 20 functions as a stopper. That is, the pressing member 30 is pressed in, and if the plate 90 hits the rim portion 21 of the housing 20, it is not pressed in further. Thus, the stroke of the pressing member 30 is up to S2, and the output value does not increase further, and overloading of the load sensor 10 is prevented.

[0133] (Second Embodiment)

[0134] Figure 7 An exploded perspective view of the load sensor device of the second embodiment.

[0135] Figure 8 A cross-sectional view illustrating the configuration of the load sensor device of the second embodiment.

[0136] In the load sensor device IB of the second embodiment, the buffer portion 50 has the second soft elastic member 52. That is, the buffer portion 50 has the second soft elastic member 52 disposed on the side of the elastic support portion 33 opposite the elastic body 31 as the leaf spring portion 330. In addition, in the second embodiment, the buffer portion 50 has both the first soft elastic member 51 and the second soft elastic member 52, but can have only the second soft elastic member 52. Furthermore, the second soft elastic member 52 can be formed integrally with the elastic body 31.

[0137] The buffer portion 50 has the second soft elastic member 52, and thus, when an impact is applied to the pressing member 30, the elastic support portion 33 that elastically deforms comes into contact with the second soft elastic member 52, and thus, the elastic deformation of the elastic support portion 33 can be moderated.

[0138] The second soft elastic component 52 has a second through-hole 52h. Thus, when a load is applied to the elastic body 31, the elastic body 31 or a component disposed between the elastic body 31 and the rigid pressing portion 32 and the rigid pressing portion 32 come into contact with each other via the second through-hole 52h. In other words, even if the second soft elastic component 52 is disposed on the side of the leaf spring opposite the elastic body 31, the elastic body 31 or a component disposed between the elastic body 31 and the rigid pressing portion 32 and the rigid pressing portion 32 can still come into direct contact with each other via the second through-hole 52h, allowing the load to be transmitted from the elastic body 31 to the pressing component 30 without intervening through the second soft elastic component 52.

[0139] (Third embodiment)

[0140] Figure 9 It is an exploded perspective view illustrating the configuration of a load sensor device according to a third embodiment.

[0141] Figure 10 It is a cross-sectional view illustrating the configuration of a load sensor device according to a third embodiment.

[0142] In addition to the configuration of the load sensor device 1 of the first embodiment, the load sensor device 1C of the third embodiment further includes a rigid plate portion 60 between the elastic body 31 and the rigid pressing portion 32. The rigid plate portion 60 has the same rigidity as the rigid pressing portion 32 and can be made of a material such as stainless steel, similar to the rigid pressing portion 32.

[0143] In the previously described load sensor device 1, the elastic body 31 directly pressed the rigid pressing portion 32. However, in the load sensor device 1C, the load borne by the elastic body 31 is transmitted to the rigid pressing portion 32 via the rigid plate portion 60. The rigid plate portion 60 has a protrusion 61 on the side facing the rigid pressing portion 32, which can transmit the force to the center of the rigid pressing portion 32 without interfering with other components. Therefore, the load borne by the elastic body 31 is easily transmitted to the load sensor 10, which can achieve improved sensitivity.

[0144] (Fourth embodiment)

[0145] Figure 11 It is an exploded perspective view illustrating the configuration of a load sensor device according to a fourth embodiment.

[0146] Figure 12 It is a cross-sectional view illustrating the configuration of a load sensor device according to a fourth embodiment.

[0147] In addition to the configuration of the load sensor device 1B of the second embodiment, the load sensor device 1D of the fourth embodiment further includes a rigid plate portion 60 between the elastic body 31 and the rigid pressing portion 32, similar to the third embodiment. Because the protrusion 61 of the rigid plate portion 60 is positioned within the second through-hole 52h of the second soft elastic member 52, the protrusion 61 directly contacts the rigid pressing portion 32. Thus, similar to the load sensor device 1C of the third embodiment, in the load sensor device 1D, the load borne by the elastic body 31 is efficiently transmitted to the rigid pressing portion 32 via the rigid plate portion 60. Consequently, the load borne by the elastic body 31 is easily transmitted to the load sensor 10, thereby enhancing sensitivity.

[0148] (Fifth embodiment)

[0149] Figure 13 It is a cross-sectional view illustrating the configuration of a load sensor device according to a fifth embodiment.

[0150] In the load sensor device 1E of the fifth embodiment, the buffer portion 50 includes a portion (fluid material portion 53) made of a fluid material having a buffering property within the housing 20. For example, silicone gel, silicone oil, synthetic rubber, or a gel-like or oil-like resin can be used for the fluid material portion 53. Alternatively, the fluid material portion 53 can be formed by filling the housing portion 22 of the housing 20 with such a gel or resin.

[0151] The fluid material portion 53 may be arranged to always be in contact with the elastic support portion 33, or may be arranged to be in contact with the elastic support portion 33 when the elastic support portion 33 is elastically deformed. Thus, when an impact is applied to the pressing member 30, the elastically deformed elastic support portion 33 contacts the fluid material portion 53, thereby relieving the elastic deformation of the elastic support portion 33 and reducing the displacement speed of the rigid pressing portion 32.

[0152] (Effect of the buffer section)

[0153] Next, the effects of the buffer portion 50 applied to the load sensor device 1 of this embodiment will be described.

[0154] In order to investigate the effects of the buffer portion 50 , a load test using a load sensor device was performed.

[0155] In the load test, a weight was dropped from a height of approximately 9.2 cm onto the load sensor device to apply a load (impact load), and then a change in the output of the load sensor device in response to the normal load was measured.

[0156] In the load test, the weight of the falling weight (Japanese original: hammer) was 30g, 50g, 80g, and 100g. The initial value refers to the case where no impact load caused by the weight is applied.

[0157] The load tests measured the sensitivity (mV / V / N), offset (mV / V), and the relative value of the offset relative to the initial value of the load sensor device's output. Here, sensitivity refers to the output per unit load. Offset refers to the output under no-load conditions. The load tests were conducted on load sensor devices of the present embodiment (Inventive Examples 1 to 6) equipped with a buffer 50, a comparative example load sensor device (Comparative Example) without a buffer 50, and a reference example load sensor device (Reference Example).

[0158] Table 1 shows the configurations of Invention Examples 1 to 3 and the values ​​obtained in the load test.

[0159] Table 2 shows the configurations of Invention Examples 4 to 6 and the values ​​obtained in the load test.

[0160] [Table 1]

[0161]

[0162] [Table 2]

[0163]

[0164] In the load sensor device configurations of Examples 1 to 3 of the present invention shown in Table 1, the elastic body 31 has a hardness of 80 (Shore A hardness; hereinafter, hardness notation is the same), and the die-bonding resin 14 is epoxy resin. Furthermore, the load sensor devices of Examples 1 to 3 of the present invention include a rigid plate portion 60 between the elastic body 31 and the rigid pressing portion 32.

[0165] The configuration of the load sensor device of Example 1 of the present invention is similar to that of the load sensor device 1C of the third embodiment (see Figure 9 、 Figure 10 ) corresponds to the composition.

[0166] That is, in Example 1 of the present invention, only the first soft elastic member 51 is provided as the buffer portion 50 , and the hardness thereof is 30.

[0167] The configurations of the load sensor devices of Examples 2 and 3 of the present invention are similar to those of the load sensor device 1D of the fourth embodiment (see Figure 11 、 Figure 12 ) corresponds to the composition.

[0168] That is, in Example 2 of the present invention, a first soft elastic member 51 and a second soft elastic member 52 are provided as the buffer portion 50, the hardness of the first soft elastic member 51 is 20, and the hardness of the second soft elastic member 52 is 30. Furthermore, in Example 3 of the present invention, a first soft elastic member 51 and a second soft elastic member 52 are provided as the buffer portion 50, the hardness of the first soft elastic member 51 is 20, and the hardness of the second soft elastic member 52 is 20.

[0169] In the configurations of the load sensor devices of Examples 4 to 6 of the present invention shown in Table 2, the hardness of the elastic body 31 is 50. With respect to other configurations, Example 4 is the same as Example 1, Example 5 is the same as Example 2, and Example 6 is the same as Example 3.

[0170] Figure 14 This is a diagram illustrating the results of the load test of Example 1 of the present invention.

[0171] Figure 15 This is a diagram illustrating the results of the load test of Example 2 of the present invention.

[0172] Figure 16 This is a diagram illustrating the results of the load test of Example 3 of the present invention.

[0173] Figures 14-16 The horizontal axis represents a normal load applied to the load sensor device, and the vertical axis represents an output of the load sensor device.

[0174] like Figures 14-16 As shown, when the impact load is applied by each weight 30g, 50g and 80g, an output change (inclination and output value) substantially the same as the initial value is obtained. On the other hand, it can be seen that when the impact load is applied by the weight 100g, the slope of the output change relative to the normal load is substantially the same as the initial value, but the output value is offset in the direction of becoming lower. Therefore, the result is that the impact load up to the weight 80g is reduced by the buffering effect achieved by the buffer portion 50, which reduces the displacement speed of the rigid pressing portion 32 and thus can alleviate the impact force transmitted to the pressure-receiving portion 11.

[0175] The "Relative Offset Value" in Tables 1 and 2 is the relative value of the offset value for each weight divided by the initial offset value. As shown in Tables 1 and 2, in Examples 1 to 4 and 6 of the Invention, the relative values ​​were approximately 1 for weights less than 100g, with the relative offset value deviating from 1 only for weights of 100g. In Example 5 of the Invention, the relative offset value was approximately 1 for all weights up to 100g.

[0176] Figure 17 It is a figure which shows the result of the load test of Examples 1 to 3 of this invention corresponding to Table 1.

[0177] Figure 18 It is a graph showing the results of the load test of Examples 4 to 6 of the present invention corresponding to Table 2.

[0178] exist Figure 17 as well as Figure 18 In FIG, the horizontal axis represents the weight of the load test object, and the vertical axis represents the deflection.

[0179] It can be seen that in any of Inventive Examples 1 to 6, the output value deviation hardly changes even when subjected to an impact load of up to 80g. Furthermore, in Inventive Example 6, the deviation hardly changes even when subjected to an impact load of 100g.

[0180] Table 3 shows the configuration of the comparative example and the values ​​obtained in the load test.

[0181] [Table 3]

[0182]

[0183] In the configuration of the comparative load sensor device shown in Table 3, the elastic body 31 has a hardness of 80 and the die-bonding resin 14 is epoxy resin. The comparative load sensor device does not include the first soft elastic member 51 and the second soft elastic member 52 of the buffer portion 50 .

[0184] Figure 19 as well as Figure 20 This is a diagram illustrating the results of a load test of a comparative example.

[0185] exist Figure 19 In FIG. 1 , the horizontal axis represents a normal load applied to the load sensor device, and the vertical axis represents an output of the load sensor device.

[0186] exist Figure 20 In FIG, the horizontal axis represents the weight of the load test object, and the vertical axis represents the deflection.

[0187] like Figure 19 as well as Figure 20 As shown, in the load sensor device of the comparative example, when the impact load is applied by weights of 30g, 50g, 80g, and 100g, the heavier the weight, the lower the output value. Table 3 also confirms the following trend: even when the weight is 30g, the relative offset value deviates significantly from 1, and the relative offset value increases as the weight of the weight increases.

[0188] The results of the load tests above confirm that the load sensor devices of Examples 1 to 6 of the present invention, which include the buffer portion 50, exhibit superior impact resistance compared to the load sensor device of the comparative example, which does not include the buffer portion 50. This is presumably because the buffer portion 50 mitigates the elastic deformation of the elastic support portion 33 when an impact load is applied, thereby reducing the displacement speed of the rigid pressing portion 32 and preventing the rigid pressing portion 32 from suddenly contacting (colliding) with the pressure receiving portion 11.

[0189] On the other hand, in the comparative example load sensor device lacking the buffer portion 50, even relatively small impact loads can cause output value deviation. In particular, when the load sensor 10 uses a bridge circuit composed of multiple piezoresistive elements 122 to obtain output, the impact load applied to the pressure-receiving portion 11 easily disrupts the resistance balance of the bridge circuit. Therefore, it is conceivable that in the comparative example load sensor device lacking the buffer portion 50, even small impact loads can significantly damage the bridge circuit, resulting in noticeable output value deviation.

[0190] Table 4 shows the configurations of Reference Examples 1 and 2 and the values ​​obtained in the load tests.

[0191] [Table 4]

[0192]

[0193] In the load sensor devices of Reference Examples 1 and 2 shown in Table 4, the die-bonding resin 14 is silicone. The load sensor devices of Reference Examples 1 and 2 do not include either the first soft elastic member 51 or the second soft elastic member 52 of the buffer portion 50 .

[0194] In Reference Example 1, the hardness of the elastic body 31 is 80.

[0195] In Reference Example 2, the hardness of the elastic body 31 is 50.

[0196] Figure 21 It is a figure which shows the result of the load test of Reference Examples 1 and 2 corresponding to Table 4.

[0197] exist Figure 21 In FIG, the horizontal axis represents the weight of the load test object, and the vertical axis represents the deflection.

[0198] It can be seen that in both Reference Examples 1 and 2, the output value deviation hardly changes even when subjected to an impact load of up to 80g. This suggests that by forming the die-bonding resin 14 from a soft material, the same effect (improvement in impact resistance) as when the buffer portion 50 is provided can be achieved.

[0199] As described above, according to the present embodiment, it is possible to provide the load sensor devices 1 , 1B, 1C, 1D, and 1E that can achieve high accuracy of detection values ​​and obtain excellent impact resistance.

[0200] Furthermore, while the embodiments have been described above, the present invention is not limited to these examples. For example, any technical solution obtained by adding, deleting, or modifying the design of the above-described embodiments, or any technical solution obtained by appropriately combining the features of the exemplary embodiments, as long as the gist of the present invention is present, is within the scope of the present invention.

Claims

1. A load sensor device, characterized in that: have: A load sensor having a pressure-receiving portion; a housing for housing the load sensor; an elastic body that bears a load and presses the load sensor; and The pressing member is provided between the elastic body and the load sensor. The pressing component has: a rigid pressing portion capable of contacting the pressed portion; and The elastic support portion supports the rigid pressing portion on the housing. When no load is applied to the elastic body, a gap is provided between the rigid pressing portion and the pressure receiving portion. When a load is applied to the elastic body, the elastic support portion elastically deforms in such a manner as to reduce the gap between the rigid pressing portion and the pressure receiving portion. The load sensor device includes a buffer portion capable of relieving elastic deformation of the elastic support portion.

2. The load sensor device according to claim 1, wherein The elastic support portion includes a leaf spring portion extending from the rigid pressing portion in a direction intersecting with a load application direction.

3. The load sensor device according to claim 2, wherein: The leaf spring portion and the rigid pressing portion are integrally provided.

4. The load sensor device according to claim 2 or 3, wherein: The buffer portion includes a first soft elastic member disposed on a side of the pressing member that faces the load sensor.

5. The load sensor device according to claim 4, wherein The first soft elastic component has a first through hole. When a load is applied to the elastic body, the rigid pressing portion and the pressure receiving portion can come into contact with each other via the first through-hole.

6. The load sensor device according to claim 2 or 3, wherein: The buffer portion includes a second soft elastic member disposed on a side of the leaf spring portion that is opposite to the elastic body.

7. The load sensor device according to claim 6, wherein: The second soft elastic component has a second through hole. When a load is applied to the elastic body, the elastic body or a member disposed between the elastic body and the rigid pressing portion is in contact with the rigid pressing portion via the second through-hole.

8. The load sensor device according to any one of claims 1 to 3, wherein: The buffer portion includes a portion made of a fluid material having buffering properties within the housing.

9. The load sensor device according to any one of claims 1 to 3, wherein: The housing includes a stopper that limits an amount of deformation of the elastic body in a load application direction when a load is applied to the elastic body.

10. The load sensor device according to any one of claims 1 to 3, wherein: The peripheral edge portion of the pressing member is fixed to the housing.

11. The load sensor device according to any one of claims 1 to 3, wherein: When viewed from the load application direction, the rigid pressing portion entirely overlaps with the load receiving portion of the elastic body, and the pressure receiving portion entirely overlaps with the rigid pressing portion.

12. The load sensor device according to any one of claims 1 to 3, wherein: The load sensor has: a displacement portion that is displaced by the load borne by the pressure-receiving portion; and The plurality of piezoresistive elements electrically detect the displacement of the displacement portion.

13. The load sensor device according to any one of claims 1 to 3, wherein: The buffer portion is provided in contact with the elastic support portion.

14. The load sensor device according to claim 3, wherein The buffer portion includes a gel-like resin adhered to the elastic support portion.

15. The load sensor device according to any one of claims 1 to 3, wherein: A rigid plate portion is provided between the elastic body and the rigid pressing portion.

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