JP2008002997A - Load detecting device and its method of making - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately form a gap between a strainpart and a stopper without needing high machining precision as much as the conventional. <P>SOLUTION: A load detecting device 1 is provided with a strain part 2b for generating strain by receiving load input from a load input part 2a and stoppers 5 and 6 for regulating straining by exceeding a constant range by the strain part 2b; wherein at least a part of the stoppers 5 and 6 comprises plastic deformation parts 3a and 4a composed of a plastically deforming material; while bringing a contact part 2c contacted on the stoppers 5 and 6 by being deformed together with the strain part 2b into contact with the plastic deformation parts 3a and 4a of the stoppers 5 and 6 or allowing them to position extremely near to them, the load of prescribed amount from the load input part 2a is input in the state and the plastic deformation parts 3a and 4a are plastically deformed by contacting the contact part 2c on the stoppers 5 and 6; and a gap of the size corresponding to the load of the prescribed amount is formed between the plastic deformation parts 3a and 4a and the contact part 2c. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a load detection device and a manufacturing method thereof. More specifically, the present invention relates to an improvement in the structure and manufacturing method of a load cell having a stopper for restricting a movable region of a strain generating portion that receives a load and generates strain.

  One of the load detection devices used for measuring the weight and load is an electric load sensor that uses the principle that the electric resistance changes depending on the amount of strain of the metal, a so-called load cell. In addition, in such a load detection device, in order to regulate and protect the strain generating portion provided in the device (a portion made of a strain generating body that generates strain by the action of a load) from being distorted beyond a certain range. Some have a stopper.

Conventionally, as a load detection device having such a structure, for example, a vehicle seat such as a driver's seat has been proposed that includes a displacement regulating mechanism that regulates the displacement of the seat rail with respect to the seat fixing portion within a certain range. (For example, refer to Patent Document 1). Further, the plate spring member constituting the mounting member is provided with an engaging portion, and the vertical displacement of the movable rigid body portion of the strain generating portion is regulated by a predetermined amount by engaging with the engaging portion. An apparatus provided with a stopper member has also been proposed (see, for example, Patent Document 2).
Japanese Patent No. 3683712 JP 2001-141553 A

  However, the load detection apparatus provided with the stopper mechanism for restricting the displacement within a certain range as described above has the following problems. That is, in the case of the prior art, since a displacement restricting stopper is provided outside the sensor including the strain generating portion (strain generating body), dedicated parts may increase. In addition, a gap (gap) is formed between the strained portion and the stopper in consideration of the displacement of the strained portion when a load is applied, but very high dimensional accuracy and machining accuracy are required. Yes. For this reason, there has been a problem that the accuracy cannot be obtained in mass production, the cutting process is forced to obtain the accuracy, and the cost is increased to specially manage the accuracy. On the other hand, if the dimensional tolerance of the stopper is increased, the displacement of the strain generating body increases. For example, if the stopper is provided in a vehicle seat, the displacement of the seat increases accordingly. There were problems such as rattling and worsening ride comfort.

  Therefore, the present invention provides a load detection device capable of forming a gap (gap) between a strain-generating portion and a stopper with high accuracy without requiring high processing accuracy as in the past, and a method for manufacturing the same. With the goal.

  In order to solve this problem, the present inventor has made various studies. The load detection device provided with the load cell which is the subject of the present invention is a device that converts a minute strain amount due to a load into an electric signal, and handles an extremely small strain amount in the first place. Then, although it is such a very small amount of distortion, it is directly connected to the fact that it is necessary to form a fixed interval between the stopper and the labor and cost. The present inventor who has further studied by focusing on this point has come to know means for solving such a problem.

  The present invention is based on such knowledge, a load input portion to which an external load is input, a strain generating portion that receives distortion from the load input portion, and the strain generating portion is in a certain range. In a manufacturing method for manufacturing a load detection device comprising a stopper that restricts distortion beyond the range, at least a part of the stopper is a plastic deformation portion made of a material that plastically deforms, together with the strain generation portion The abutting portion that is displaced to abut against the stopper and the plastic deformation portion of the stopper are brought into contact with each other or are positioned in the vicinity of the stopper. In this state, a load having a predetermined magnitude is input from the load input portion. The plastic deformation portion is plastically deformed by bringing a contact portion into contact with the stopper, and a gap having a size corresponding to the predetermined load is provided between the plastic deformation portion and the contact portion. Once formed Is Umono.

  As described above, when a predetermined load is input from the outside via the load input portion, the strain generating portion is distorted by receiving the input load, and the contact portion is also displaced in response to the distortion. The abutting portion is displaced by an amount corresponding to the magnitude of the input load and presses the plastic deformation portion of the stopper to cause plastic deformation. After that, if the input load is removed, the displaced contact part returns to the original position (neutral position in the state where no load is received), and the deformed contact part and the deformed part are deformed. A gap is formed between the plastic deformation portion. Here, for example, in the case of a load cell using a strain gauge, the displacement amount (strain amount) of the strain generating portion and the contact portion is a fixed amount determined according to the input load. The formed gap (gap between the stopper) is a constant interval corresponding to the load. In other words, regardless of the initial state, by carrying out a series of processes such as load input and removal, a gap of a constant interval can be formed between the contact portion and the stopper without undergoing cutting or the like. it can.

  Further, in the method for manufacturing the load detection device as described above, the stopper has a structure including at least a pair of plastic deformation portions disposed so as to sandwich the contact portion, and the plastic deformation portion of the stopper is provided. It is preferable that both the pair of plastic deformation portions be plastically deformed by applying a load for plastically deforming the material in one direction and the opposite direction. In such a case, for example, separate stoppers for loads having different directions such as a compressive load and a tensile load can be formed in a state where gaps with a constant interval are formed between the stoppers.

  Moreover, in this manufacturing method, it is preferable to provide the stopper in advance with a recess for reducing resistance during deformation of the plastic deformation portion. For example, a concave portion formed by a constriction or a concave groove makes it easy to deform a plastic deformation portion by reducing resistance during deformation.

  Furthermore, in the present invention, a load having a magnitude corresponding to the upper limit value of the load acting on the strain generating portion is input as the predetermined magnitude load. According to this, a gap having a size corresponding to a predetermined load upper limit value is formed between the strain generating portion (contact portion) and the stopper. Therefore, when the load detection device is used, while a load smaller than the load upper limit value is applied, there is a gap between the strain generating portion (contact portion) and the stopper, but this load upper limit value is exceeded. When the load is applied, the strain generating portion (contact portion) comes into contact with the stopper. Thereby, it is possible to protect or restrain the strain generating portion by restricting or suppressing the strain generating portion from being distorted beyond a certain range.

  In addition, the present invention is directed to a load input unit to which an external load is input, a strain generating unit that receives distortion from the load input unit, and a strain generating unit that distorts beyond a certain range. In a load detection device comprising a stopper that restricts the contact and a contact portion that is displaced together with the strain-generating portion and contacts the stopper, at least a part of the stopper is disposed so as to sandwich the contact portion. A plastic deformation portion made of a plastically deformed material, and a load for plastically deforming the plastic deformation portion of the stopper through the contact portion in one direction and the load input portion. Is characterized in that, when applied in the opposite direction, a concave portion for reducing the resistance during deformation of the plastic deformation portion is provided in advance in a part of the plastic deformation portion.

  In this load detection device, it is possible to protect the strain generating portion by restricting the movement of the abutting portion that is displaced together with the strain generating portion. Since a part of the stopper in this case is composed of a plastic deformation part arranged so as to sandwich the contact part, even if the contact part is displaced in any direction, the function of such a stopper causes the movement. (Displacement) can be regulated. In addition, since the load detection device according to the present invention includes a recess for reducing resistance during deformation of the plastic deformation portion, a load having a predetermined magnitude in the manufacturing method as described above, that is, in the manufacturing process. When the manufacturing method of deforming the plastically deformed portion by inputting the above is advantageous in that the plastically deformable portion is easily deformed. For this reason, it is easy to form a gap at a constant interval between the strain generating portion (contact portion) and the stopper.

  Furthermore, the present invention provides a load input portion to which a load from the outside is input, a strain generating portion that receives a load input from the load input portion and generates strain, a support member that supports the strain generating portion, A stopper surface that is formed on the support member and that contacts the contact surface of the strain-generating portion when the strain-generating portion attempts to distort beyond a certain range and regulates the strain of the strain-generating portion. The support member is formed with a plastic deformation portion that is plastically deformed by applying a load to the load input portion in a state where the stopper surface and the contact surface are in contact with each other. .

  As described above, when a predetermined load is input from the outside via the load input portion, the strain generation portion is distorted due to the input load, and the contact portion (contact surface) is also displaced in response to the distortion. To do. The contact portion (contact surface) is displaced by an amount corresponding to the magnitude of the input load, and the plastic deformation portion constituting a part or all of the stopper (stopper surface) is pressed and plastically deformed. After that, if the input load is removed, the displaced contact portion (contact surface) returns to the original position (neutral position when no load is received), and the returned contact. A gap is formed between the portion and the plastic deformation portion after deformation. In this case, since the strain amount of the strain generating portion and the displacement amount of the contact portion are fixed amounts determined by the input load, by performing a series of processes of load input and removal regardless of the initial state before the load input. In the load detection device according to the present invention, a gap having a constant interval is formed between the contact portion and the stopper.

  According to the load detection device according to the present invention, it is possible to form a gap (gap) between the strain-generating portion and the stopper with high accuracy without requiring high machining accuracy as in the past.

  Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.

  1 to 5 show an embodiment of the present invention. The load detection device 1 according to the present invention includes a load input unit 2a to which a load from the outside is input, a strain generating unit 2b that receives the load input from the load input unit 2a and generates strain, and the strain generating unit. The stoppers 5 and 6 that restrict the 2b from being distorted beyond a certain range are provided. Here, in this embodiment, at least a part of the stoppers 5 and 6 are plastic deformation parts 3a and 4a made of a material that plastically deforms, and a part of the load detection body 2 (specifically, the contact part 2c). The plastic deformation portions 3a and 4a are deformed by using a to form a gap (stopper gap) at a predetermined interval between the contact portion 2c and the stoppers 5 and 6.

  First, the outline of the load detection device 1 will be described. The load detection device 1 of the present embodiment is one of devices used for measuring weight and load, and uses an electric sensor (load cell) whose electric resistance changes depending on the amount of metal strain. The load detection device 1 is applied to a device for detecting a load acting on a vehicle seat such as a passenger seat or a driver's seat, for example (see FIG. 5). In the present embodiment, a case will be described in which the load detection device 1 is used as a load detection device in such a vehicle seat. However, this is only one suitable application example of this apparatus, and application to other than this is not prevented.

  The load input unit 2a is a part to which a load from the outside is input, and constitutes a load detection body 2 that is one of the components constituting the load detection device 1 (see FIGS. 1 and 4). The load input portion 2a is formed in a cylindrical shape as in the present embodiment, for example, and can be easily attached to the vehicle seat, and can easily transmit loads in various directions or sizes to the strain generating portion 2b. It is preferable that In the present embodiment, a screw is cut on the outer periphery of the load input portion 2a (see FIG. 1).

  The strain generating portion 2b is a portion that receives a load and generates internal stress to generate strain. For example, in the load detection device 1 of the present embodiment, the portion indicated by reference numeral 2b in FIG. 2 among the portions near the bottom of the load detection body 2 functions as a strain generating portion (see FIG. 2). In addition, the region of the imaginary line indicated by reference numeral 2b is not a strict strain generating portion, but a portion near the upper portion of the portion where the strain gauge 7 is provided functions as a strain generating portion. is there.

  The abutting portion 2c is formed so as to be displaced and abutted against the stoppers 5 and 6 when the strain generating portion 2b is distorted. For example, in the case of the present embodiment, as shown in the drawing, the load detector 2 is formed in an integrated structure in which a plurality of cylindrical bodies having different diameters are combined, and the load detector 2 is positioned in the middle of the load detector 2. The large-diameter cylindrical body to be used is a flange portion, and the flange portion is caused to function as a contact portion 2c that directly contacts the stoppers 5 and 6 (see FIGS. 1 to 3).

  The stoppers 5 and 6 are for restricting the above-described strain generating portion 2b from being distorted beyond a certain range. For example, in the case of this embodiment, the stoppers 5 and 6 are displaced as the strain generating portion 2b is distorted. By restricting the movement of the contact portion 2c, the strain generating portion 2b is protected. The size and shape of the stoppers 5 and 6 are not particularly limited as long as they can restrict and protect the displacement of the strain generating portion 2b, but in the present embodiment, for example, the upper surface of the contact portion 2c. The movement of the contact portion 2c is regulated by using a pair of upper and lower stoppers 5 and 6 sandwiched from the side and the lower surface side (see FIGS. 2 and 3).

  In addition, the stoppers 5 and 6 are not only integral structures, but may be configured by combining a plurality of members. For example, in the present embodiment, two annular members, a support member (hereinafter referred to as a flange member) 3 that regulates the upper surface side of the contact portion 2c and a ring member 4 that regulates the lower surface side of the contact portion 2c are combined. The stoppers 5 and 6 are configured.

  The flange member 3 is a member provided so as to restrain the load detection body 2 from the outer peripheral side, and a circular hole through which a part of the load detection body 2 can be passed is provided at the center. Further, the flange member 3 is appropriately provided with a bolt hole 3c that can be used when, for example, it is attached to a component of a vehicle seat (see FIGS. 1 and 2). FIG. 4). The flange member 3 provided so as to suppress the load detection body 2 from the outer peripheral side supports a member that supports the strain generating portion 2b of the load detection body 2 (or supports the load detection body 2 itself including the strain generating portion 2b. Thus, it functions as a member that causes the strain generating portion 2b, the contact portion 2c, and the like to exhibit a predetermined function.

  Furthermore, when the strain generating portion 2b tries to strain beyond a certain range, the flange member 3 has a contact surface of the strain generating portion 2b (more specifically, a displacement caused by strain of the strain generating portion 2b). The stopper 5 is formed so as to abut against the surface of the abutting portion 2c to restrict the distortion of the strain generating portion 2b (see FIG. 2). For example, in the case of the present embodiment, a flange-shaped portion that protrudes toward the inner peripheral side is formed at the inner peripheral upper end portion of the flange member 3, and the stopper surface formed by the bottom surface of the flange-shaped portion is caused to function as the stopper 5. I have to.

  On the other hand, the ring member 4 is an annular member that fits into the inner periphery of the flange member 3 described above (see FIG. 2). Similar to the flange member 3, the ring member 4 provided to suppress the load detection body 2 from the outer peripheral side includes a support member (or a strain generation section 2 b) that supports the strain generation section 2 b of the load detection body 2. It functions as a member that supports the load detector 2 itself and causes the strain generating portion 2b, the contact portion 2c, etc. to exhibit a predetermined function.

  The ring member 4 includes a contact surface of the strain generating portion 2b when the strain generating portion 2b tries to strain beyond a certain range (more specifically, a contact surface that is displaced with strain of the strain generating portion 2b). A stopper 6 is formed to abut against the surface of the contact portion 2c) and restrict the distortion of the strain generating portion 2b (see FIG. 2). For example, in this embodiment, the stopper surface formed on the upper surface of the ring member 4 is made to function as the stopper 6.

  Furthermore, it is preferable that at least a part of the above-described stoppers 5 and 6 is made of a plastically deformable material. In this case, the plastically deformed portion is deformed by being pressed from the contact portion 2c, and after being pressed by the contact portion 2c, the state of being deformed can be maintained unless an external force is applied. For example, in this embodiment, plasticity is applied by applying a load to the load input portion 2a in a state where the stoppers 5 and 6 and the contact portion 2c are in contact with each of the support members (flange member 3 and ring member 4) described above. The deformed plastic deformation portions 3a and 4a are formed (see FIG. 2). By constituting a part or all of the stoppers 5 and 6 with such plastic deformation portions 3a and 4a, between the stoppers 5 and 6 (or the plastic deformation portions 3a and 4a) and the contact portion 2c, A gap having a predetermined width can be formed later. That is, although detailed contents will be described later, in the present embodiment, after the load detector 2, the ring member 4, and the flange member 3 are assembled, a load having a predetermined magnitude is input from the load input portion 2a. By displacing the contact portion 2c, the plastic deformation portions 3a and 4a are deformed by an amount corresponding to the magnitude of the load. In such a case, it is possible to form a minute gap of a predetermined size between the contact portion 2c and the plastic deformation portions 3a and 4a regardless of the state at the time of assembly.

  Moreover, it is preferable that the plastic deformation portions 3a and 4a and the vicinity thereof have a shape suitable for plastic deformation. For example, in the present embodiment, the plastic deformation portions 3a and 4a are provided with recesses 3b and 4b formed of constrictions and grooves so that plastic deformation is easily performed. In other words, the thickness of the plastic deformation portion 3a is not made uniform, but a recess 3b is provided at the base portion of the portion to be plastically deformed, and the thickness in the vicinity of the recess 3b is made thin so that the plastic deformation portion 3a can be easily deformed. (See FIG. 2).

  In this embodiment, the ring member 4 is also provided with a recess 4b so that the plastic deformation portion 4a is easily deformed. Specifically, a concave portion 4b formed of a groove that circulates on the inner peripheral surface of the ring member 4 is provided, and the plastic deformable portion 4a is shaped like a cantilever so as to be easily deformed (see FIG. 2). ). In other words, by forming the concave portion 4b having a shape such that the lower side of the portion to be plastically deformed is formed, the plastic deformable portion 4a is easily plastically deformed when a predetermined amount of load is input. I am doing so.

  Furthermore, it is also preferable that the load detection device 1 adopts a structure that makes the plastic deformation portion 4a as described above easier to deform. As an example, in this embodiment, the plastic deformation portion 4a can be more positively deformed by forming the lower surface of the contact portion 2c into a stepped convex shape. That is, the lower surface of the abutting portion 2c has a stepped shape having a diameter smaller than that of the corresponding abutting portion 2c, and the region where the stopper 6 is pressed is narrowed so that the input load acts on the plastic deformation portion 4a intensively ( (See FIGS. 2 and 3). In such a case, since a load can be concentratedly applied to the plastic deformation portion 4a, there is an advantage that the plastic deformation portion 4a can be further easily deformed even when a load having the same magnitude is input. .

  In the load detection device 1, the load detection body 2 and the flange member 3 including the stopper 5 are integrated via the ring member 4. For example, in the present embodiment, the load detection body 2 and the ring member 4 are welded, and the ring member 4 and the flange member 3 are further welded to form an integrated structure (see FIG. 2). As the welding, for example, laser welding or electron beam welding can be performed. In FIG. 2, these welded portions are denoted by reference numeral 8.

  Further, the load detection device 1 preferably has a structure for reducing the influence of heat. For example, in the present embodiment, as a structure for reducing the influence of heat, a circular concave groove 4c is provided on the bottom surface of the ring member 4 (see FIG. 2). Such a concave groove 4c facilitates deformation of the ring member 4 itself, thereby making it possible to absorb the expansion or contraction due to a temperature change, for example, during welding and to reduce the influence as much as possible. Such a structure that can reduce the influence of heat as much as possible is particularly preferable when the load detector 2, the flange member 3, the ring member 4 and the like are integrated as described above.

  Further, the load detection device 1 is provided with a strain gauge 7 for detecting strain at the time of load input. For example, in the present embodiment, the strain gauge 7 is arranged so as to be positioned on the lower surface of the strain generating portion 2b (see FIG. 2). The strain gauge 7 transmits a signal for measuring the amount of strain when a load is applied, using the principle that the electrical resistance changes according to the amount of strain of the metal.

  Then, the manufacturing method of the load detection apparatus 1 is demonstrated.

  First, the load detection body 2 and the ring member 4 having the above-described structure are welded, and further, the ring member 4 and the flange member 3 are welded to integrate them (see FIG. 2). In the case of the present embodiment, at this point in time, the distance between the stopper gaps (the gap between the contact portion 2c and the stopper 5 and the gap between the contact portion 2c and the stopper 6) is not adjusted. The stoppers 5 and 6 may be brought into contact with each other or placed in the vicinity of the poles.

  Subsequently, under this state, a load having a predetermined magnitude is input as a preload from the load input portion 2a (see FIG. 1). For example, in the present embodiment, a load having a magnitude corresponding to the upper limit value of the load acting on the strain generating portion 2b when the load detecting device 1 is used is input as the load having the predetermined magnitude. Although the specific numerical value of this upper limit value can take various values depending on conditions such as the object of use and usage conditions, for example, if the load detection device 1 is used for a vehicle seat, the vehicle is light. This is a load of about 5000N to 15000N that can act when a collision occurs, and this value (5000N) if the stoppers 5 and 6 are intended to function when, for example, a load of 5000N is applied during use. The plastic deformation portions 3a and 4a are deformed by a predetermined amount by inputting the above load. In such a case, each plastic deformation portion 3a, 4a is deformed by the amount of displacement when the load 5000N is applied and retains its shape. Therefore, when the load detecting device 1 is functioning, the load 5000N is actually When it acts, the stoppers 5 and 6 act.

  Furthermore, in this embodiment, when inputting a predetermined load (pre-load), the load is applied in both the compression direction and the tensile direction. That is, for example, by first inputting a compressive load (a load acting downward in the figure in the case of the present embodiment), a compressive stress is generated in the strain generating portion 2b, and the contact portion 2c is displaced downward. In this case, the contact portion 2c is displaced downward by an amount corresponding to the magnitude of the load, and the plastic deformation portion 4a is pressed and plastically deformed (see FIG. 3). Subsequently, by inputting a tensile load (a load acting upward in the figure in the case of the present embodiment) to the load input portion 2a, a tensile stress is generated in the strain generating portion 2b, and the contact portion 2c faces upward. Displace to. In this case, the contact portion 2c is displaced upward by an amount corresponding to the magnitude of the load, and the plastic deformation portion 3a is pressed and plastically deformed (see FIG. 3).

  As described above, when both loads in the compression direction and the tensile direction are applied, the input load is removed. As a result, the displaced contact portion 2c returns to its original position (neutral position when no load is applied), and between the returned contact portion 2c and the plastic deformation portions 3a and 4a after deformation. A gap is formed (see FIG. 3). In this case, since the deformed plastic deformation portions 3a and 4a are not further deformed unless they are subjected to an external force, in the case of the present embodiment, they remain in a deformed state under the action of the predetermined preload described above. It has become. Accordingly, a gap having a width corresponding to the magnitude of the preload is formed between the contact portion 2c that has returned to the neutral position and the stoppers 5 and 6 (the plastic deformation portions 3a and 4a). (See FIGS. 2 and 3). Incidentally, the displacement generated in the load detection device 1 using the load cell is, for example, on the order of several μm to several tens of μm when a load of 1000 N is applied, and the size of the stopper gap formed by the manufacturing method of the present embodiment. In general, the width (width) is about the same.

  In addition, when inputting the preload in both the upper and lower directions as described above, the input order of the compression load and the tensile load is not limited. In short, the upper and lower stopper gaps (the gap between the contact portion 2c and the stopper 5 and the gap between the contact portion 2c and the stopper 6) are set to predetermined intervals by finally applying loads in both directions sequentially. Is sufficient (see FIG. 3). Therefore, the compression load and the tensile load may be applied alternately and repeatedly, not once. In addition, when the load is input a plurality of times as described above, the load having the same magnitude as the so-called alternating load may be repeatedly applied, or the load may be gradually increased. It is also possible to make it. In the latter case, the interval between the stopper gaps can be gradually widened to finally form a desired interval.

  Further, although not particularly mentioned in the present embodiment, the operation time in the case where the preload is applied as described above is not limited. If the plastic deformation portions 3a and 4a can be plastically deformed until a gap of a predetermined width is formed between the abutment portion 2c and the stoppers 5 and 6, this operation time is long even if it is short. It doesn't matter.

  Next, the vehicle seat provided with the load detection device 1 of the present embodiment will also be described (see FIG. 5). As described above, the load detection device 1 is applied as a device for detecting a load acting on a vehicle seat (indicated by reference numeral 12 in FIG. 5) such as a passenger seat or a driver's seat, for example, and has a load detection function. The attached sheet 11 is configured (see FIG. 5).

  For example, the seat 11 with a load detection function shown in FIG. 5 has a function for measuring a load acting on the vehicle seat 12, and includes a support base 13 fixed to a vehicle (not shown), A plurality of load detection devices 1 disposed at least front and rear on the support base 13, a connecting member 16 that connects the load input portions 2a of those load detection devices 1 that are positioned at the front and rear, a sheet support member 17, And a stopper 18 for preventing the connecting member 16 from deforming at least in the vertical direction at the time of a collision with the vehicle.

  The vehicle seat 12 is provided as a passenger seat in an automobile or the like. As the vehicle seat 12, for example, there is a case where an elevating mechanism that elevates and lowers the seat surface via a link is provided, and the load detection device 1 according to the present invention is also provided accompanying such a mechanism. There is a case.

  The support base 13 is fixed to the vehicle as a pedestal that supports the vehicle seat 12. Although the thing with various shapes and a mechanism can be utilized as the support stand 13, for example, in this embodiment, the support stand 13 comprised by the brackets 31 and 32, the lower rail 33, and the upper rail 34 is employ | adopted. (See FIG. 5).

  One end of each of the brackets 31 and 32 is a support member that is fixed to the vehicle floor, and supports the lower rail 33 at the other end. For example, in the present embodiment, the front bracket 31 and the rear bracket 32 are arranged at the front and rear to support the lower rail 33 (see FIG. 1 and the like).

  The lower rail 33 is a member fixed to the brackets 31 and 32, and is installed, for example, in a form extending in the front-rear direction on each of the left and right sides of the vehicle seat 12. The upper rail 34 is a member that is slidable in the front-rear direction along the lower rail 33. The load detection device 1 is provided on the upper rail 34, and the connecting member 16 and the seat support member 17 are further provided via the load detection device 1 (see FIG. 5). The shape of the upper rail 34 is not particularly limited. For example, in the case of the present embodiment, the upper rail 34 is formed in a channel shape having a top plate 34a and has a structure in which the load detection device 1 can be easily attached.

  The load detection device 1 is a sensor that measures the load based on the strain amount of the strain generating portion 2b that generates strain due to the load input from the load input portion 2a. For example, four load detection devices 1 for configuring the seat 11 with a load detection function are arranged in four lower corners of the vehicle seat 12 to measure loads acting on each position. In addition, in FIG. 5 represented by a side view, the front side load detection device is indicated by reference numeral 1A, and the rear load detection device is indicated by reference numeral 1B, respectively, and two front and rear sensors are shown (see FIG. 5).

  Here, although the outline | summary of the load detection apparatus 1 of this embodiment is as having mentioned above, it is as follows when it demonstrates easily. In other words, the load detection device 1 transmits a signal for measuring the amount of strain when a load is applied using a strain gauge whose electrical resistance changes in accordance with the amount of strain of the metal. It is configured to detect a slight distortion of the generated strain generating portion 2b. Moreover, the load input part 2a provided in the center part of each load detection apparatus 1 is a site | part to which the load from the outside is input, and is comprised so that a distortion may be produced in the strain generation part 2b. For example, in the case of this embodiment, a load is input from these load input portions 2a via the connecting members 25 and 26 (see FIG. 5). In addition, the upper end part of each load input part 2a is threaded so that the nut 24 may be screwed together (refer FIG. 1, FIG. 5).

  Further, the load detection device 1 includes a large-diameter flange member 3, and the load detection device 1 can be fixed using a through hole, a bolt, or the like provided in the flange member 3. For example, in the case of this embodiment, the bolt 22 that penetrates the top plate 34 a of the upper rail 34 described above is also passed through the flange member 3 and fastened with a nut 23 to fix each load detection device 1 on the upper rail 34. (See FIG. 5). The connecting member 16 is provided with a through hole for avoiding interference with the tip of each bolt 22 at a corresponding location.

  The connecting member 16 is a member for connecting the load input portions 2a of the load detection device 1 arranged in the front and back. For example, in the case of the present embodiment, the load input portion 2a of the load detection device 1A and the load described above are connected. The load input part 2a of the detection apparatus 1B is connected in a state where the nuts 24 are screwed together (see FIG. 5). Intermediate brackets 25 and 26 are respectively attached to the front and rear portions of the connecting member 16 by using fastening means 27 including bolts and nuts.

  The intermediate brackets 25 and 26 are members that are interposed between the connecting member 16 and the seat support member 17 and transmit a load acting on the vehicle seat 12. The arrangement of the intermediate brackets 25 and 26 is not particularly limited. For example, in the present embodiment, the front intermediate bracket 25 is arranged in front of the load detection device 1A, and the rear intermediate bracket 26 is in front of the load detection device 1B. Are arranged (see FIG. 5). Further, in the present embodiment, the displacement amount (offset amount) of the intermediate bracket 25 with respect to the load detection device 1A is larger than the displacement amount (offset amount) of the intermediate bracket 26 with respect to the load detection device 1B. It is arranged.

  The seat support member 17 is a member that supports the vehicle seat 12 and transmits a load acting on the vehicle seat 12 to the connecting member 16 via the intermediate brackets 25 and 26. The above-described intermediate brackets 25 and 26 are attached to the front and rear of the seat support member 17 of the present embodiment, respectively.

  Here, an example in the case where an excessive load is applied due to a vehicle collision or the like is as follows. That is, the support base 13 and the like having the above-described structure often receive an excessive load when it is rear-projected from the rear. In such a case, the vehicle seat 12 and the seat support member 17 are received. A load is applied so as to recline back (see the arrow in FIG. 5). On the other hand, the vehicle seat 12 and the like has a structure that rotates around a fulcrum (indicated by reference numeral 12a in FIG. 5) in the vicinity of the occupant's buttocks. Is subjected to the action of floating more greatly (see FIG. 5). At this time, the connecting member 16 is subjected to an action in which the front end is strongly pulled up via the front intermediate bracket 25 (see FIG. 5). However, as described above, since the connecting member 16 is fixed to the load detecting device 1 with, for example, the nut 24, a downward force, that is, the connecting member 16 is obtained as a result of the above-described action in the intermediate portion of the connecting member 16. Will be subjected to the action of a force to deform it into a V shape (see FIG. 5). The example illustrated here is an example when an excessive load is applied. For example, if a load in the direction opposite to that described above is applied, the connecting member 16 is opposite to this, that is, an intermediate portion is provided. It will receive the action of a force that tries to deform upward.

  Here, in the present embodiment, the stopper 18 is provided as a means for preventing the connecting member 16 from deforming at least in the vertical direction even when an excessive load is applied. That is, the stopper 18 restricts the movement of the connecting member 16 even when an excessive load is applied during a collision or the like, and physically prevents the connecting member 16 from being deformed. From this point of view, the specific configuration of the stopper 18 can take various forms. For example, a protrusion-shaped restriction provided between the load detection device 1 or the support base 13 and the connecting member 16 is illustrated. It can be constituted by the member 19 or can be constituted by a regulating member 10 that sandwiches the coupling member 16 and the upper rail 34 so as to regulate the deformation of the coupling member 16 to the side opposite to the upper rail 34. it can.

  As described above, according to the load detection device 1 of the present embodiment described so far, the gap (gap) between the contact portion 2c and the stoppers 5 and 6 can be made with high accuracy without requiring high machining accuracy as in the conventional case. It becomes possible to form. That is, when forming the stoppers 5 and 6 or when assembling the members, high dimensional accuracy is not required. After that, by inputting a preload, the clearance between the contact portion 2c and the stoppers 5 and 6 is increased. It can be formed with accuracy. That is, according to the present embodiment, the gap can be optimized after the assembly by applying a load after assembly, so that the stopper gap can be formed more easily and with higher accuracy than in the past. According to this, it is possible to manufacture the load detection device 1 with high accuracy without being affected by variations that are likely to occur during assembly and processing.

  And according to the technique mentioned above, the response | compatibility of changing the magnitude | size of a clearance gap by changing the magnitude | size of a preload variously is easy. For this reason, even when the load to be limited by the stoppers 5 and 6 changes depending on the specifications of the load detection device 1 or the installation target, the design can be flexibly changed to various design requirements by appropriately changing the size of the preload. There is an advantage that it can respond to.

  In addition, in the case of the conventional structure in which a stopper means for restricting displacement is provided outside the sensor including the strain generating portion 2b, there is a problem that the number of components tends to increase. According to the detection device 1, since a structure different from the conventional one can be realized, the number of parts can be reduced by that amount. In addition, since the stopper gap can be optimized afterwards as described above, high dimensional accuracy and processing accuracy as in the past are not required when processing or assembling the gap (gap). It is not affected by processing or assembly. Therefore, as a result of these, according to the above-described technique, there is an advantage that the manufacturing cost can be greatly reduced as compared with the conventional technique.

  Moreover, according to the load detection apparatus 1 of this embodiment which optimizes a stopper clearance afterwards as mentioned above, there also exists an advantage that the influence by heat can be excluded. That is, for example, in the case of a processing method that involves welding at the time of assembly, the load detection device 1 according to the present embodiment is not susceptible to heat during the optimization of the gap, whereas it is susceptible to deformation due to heat. Will not be affected.

  Furthermore, in the case of this embodiment, since the recessed parts 3b and 4b are previously formed in the site | part which is going to carry out plastic deformation, or its vicinity, there also exists an advantage that it is easy to deform | transform. In this case, it is possible to shorten the time required for processing and molding.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the above-described embodiment, the case where the same load as the compressive load and the tensile load is input as the pre-load has been described. However, the sizes of these loads may be different from each other. In short, when the load to make the stoppers 5 and 6 function when used in a vehicle or the like is different between the case of compression and the case of tension, when forming the stopper gap accordingly (during optimization) It is possible to make the input compressive load and tensile load different.

  Moreover, although the case where the vertical load (compression load and tensile load) is input as the preload has been described in the present embodiment, this is only a preferable example. That is, in the actual use in a vehicle or the like, not only a vertical load but also a load in an oblique direction and a moment depending on the case may act, and a load simulating these may be inputted as a preload. Alternatively, it is also preferable to input a vertical load calculated in consideration of these various loads (combined loads) as a preload.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall half sectional view from the front showing a schematic configuration of a load detection device according to an embodiment of the present invention, and the left half shows a sectional structure of a flange member (supporting member). It is an enlarged view which shows the load detection apparatus shown in FIG. 1 in detail centering on a contact part and a stopper. It is the further enlarged view for showing in detail centering on the circular part shown with the broken line in FIG. 2, and its peripheral part. It is a perspective view which shows roughly the whole load detection apparatus shown in FIG. It is a side view of the sheet | seat with a load detection function which shows the application example of the load detection apparatus concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Load detection apparatus, 2a ... Load input part, 2b ... Strain part, 2c ... Contact part, 3 ... Flange member (support member), 3a ... Plastic deformation part, 3b ... Concave part, 4 ... Ring member (support member) 4a ... plastic deformation part, 4b ... recess, 5 ... stopper, 6 ... stopper

Claims (6)

A load input portion to which an external load is input, a strain generating portion that receives distortion from the load input portion, and a stopper that restricts the strain generating portion from being distorted beyond a certain range; In a manufacturing method for manufacturing a load detection device comprising:
At least a part of the stopper is a plastic deformation portion made of a material that plastically deforms, and the contact portion that contacts the stopper by displacing together with the strain-generating portion and the plastic deformation portion of the stopper are brought into contact with each other. In this state, a predetermined amount of load is input from the load input portion, and the contact portion is brought into contact with the stopper to cause plastic deformation of the plastic deformation portion. A load detecting device manufacturing method, wherein a gap having a size corresponding to the load having the predetermined size is formed between a portion and the contact portion.   The stopper has a structure including at least a pair of plastic deformation portions arranged so as to sandwich the contact portion, and a load for plastically deforming the plastic deformation portion of the stopper is in one direction and this. 2. The method of manufacturing a load detection device according to claim 1, wherein both of the pair of plastic deformation portions are plastically deformed by applying in opposite directions.   The method for manufacturing a load detection device according to claim 1, wherein the stopper is provided with a concave portion for reducing resistance during deformation of the plastic deformation portion in advance.   4. The load detection device according to claim 1, wherein a load having a size corresponding to an upper limit value of a load acting on the strain-generating portion is input as the predetermined load. 5. Production method. A load input portion to which an external load is input, a strain generating portion that receives distortion from the load input portion, and a stopper that restricts the strain generating portion from being distorted beyond a certain range; A load detecting device including a contact portion that is displaced together with the strain generating portion and contacts the stopper,
At least a part of the stopper is composed of a plastic deformation portion made of a plastically deformable material disposed so as to sandwich the contact portion, and
When a load for plastically deforming the plastic deformation portion of the stopper through the contact portion is applied in one direction and the opposite direction through the load input portion, the resistance at the time of deformation of the plastic deformation portion is reduced. A load detecting device characterized in that a recess for reducing is provided in advance in a part of the plastic deformation portion. A load input unit to which an external load is input;
A strain generating portion that receives a load input from the load input portion and generates strain;
A support member for supporting the strain-generating portion;
A stopper surface that is formed on the support member and contacts the contact surface of the strain generating portion when the strain generating portion tries to strain beyond a certain range, and restricts the strain of the strain generating portion;
With
The support member is formed with a plastic deformation portion formed by plastic deformation by applying a load to the load input portion in a state where the stopper surface and the contact surface are in contact with each other. Load detection device.

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