JP5597095B2 - Washer type load cell and thrust load detection mechanism - Google Patents

Description

  The present invention relates to a washer-type load cell and a thrust load detection mechanism for detecting a thrust load acting on a shaft.

  As a conventional washer type load cell, there is one shown in Patent Document 1. This washer-type load cell is inserted into a shaft to detect a thrust load, and has a load cell body that is annular and receives the thrust load on one side. The load cell body is hollow, and a cantilever beam supported by the inner ring and the outer ring of the load cell body is formed in the width direction on one side of the load cell body. A strain gauge is attached to the inside of the one surface. Further, on the outer side of the one surface, a convex support portion for receiving a thrust load is continuously provided in the circumferential direction. With this configuration, when the support portion receives the thrust load, the beam is distorted, and the strain is detected by the strain gauge as an electrical signal to detect the thrust load.

Japanese Utility Model Publication No. 5-40424

  However, the washer type load cell has a configuration in which a beam is formed in the width direction on one side of the load cell main body. In this configuration, since the total length of the beam is limited by the width, the distance between the fulcrum and the action point cannot be set sufficiently long. Therefore, the output sensitivity characteristics are inferior, and the thrust load cannot be detected with high accuracy.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a washer-type load cell and a thrust load detection mechanism that can particularly detect a low thrust load with high accuracy.

  In order to achieve the above object, a washer-type load cell according to the present invention comprises a load cell main body that has an annular shape and receives a thrust load on one side, and a strain detection means that detects strain of the load cell main body. The load cell main body has a plurality of support portions arranged at predetermined intervals in the circumferential direction on the other surface, and is distorted with the support portions as fulcrums according to the thrust load.

  In the washer type load cell, it is desirable that the load cell main body has a protrusion having a thickness smaller than that of the support portion on one side of the support portion.

  Further, in the washer type load cell, the load cell main body has a plurality of pressure receiving portions arranged at a predetermined interval in the circumferential direction on one surface receiving pressure of the thrust load, the pressure receiving portion and the support portion. It is desirable that the arrangement phase is different in the circumferential direction.

  In the washer type load cell, it is desirable that the load cell main body is sandwiched between pressure receiving plates from both sides.

In order to achieve the above object, the thrust load detection mechanism of the present invention supports a shaft rotatably, receives a thrust load acting on the shaft, and is inserted into the shaft and pressed against the bearing. A washer type load cell comprising a deformed load cell main body, strain detecting means for detecting a strain amount of the load cell main body, and a thrust load acting on the bearing interposed between the bearing and the washer type load cell. A pressure receiving plate that transmits to

The load cell body preferably has a plurality of protrusions on both sides or one side and is distorted with the protrusions as fulcrums .

Further, it is desirable that the pressure receiving plates are formed in pairs so as to sandwich the washer type load cell from both sides.

Moreover, it is desirable that the bearings are a pair of angular ball bearings arranged in combination with the back surface.

Further, it is desirable that both ends of the shaft are rotatably supported by cylindrical roller bearings.

The bearing is preferably urged by an elastic member in a direction of pressing the washer type load cell.

  In the washer-type load cell and thrust load detection mechanism of the present invention, one side of the load cell main body has a plurality of support portions arranged at predetermined intervals in the circumferential direction. For this reason, a double-sided beam having the support portion as a fixed end is formed in the load cell main body. Moreover, since the doubly supported beam extends in the circumferential direction, its full length is sufficiently long. Therefore, the output sensitivity characteristic is improved, and particularly the detection accuracy of the low thrust load is excellent.

  In the washer type load cell and the thrust load detection mechanism, the load cell main body has a protrusion having a thickness smaller than that of the support portion on one side of the support portion. Therefore, when a thrust load exceeding the limit stress is applied to the load cell main body, the protrusions come into contact and prevent distortion deformation. Therefore, the load cell main body is not damaged and has excellent durability.

  Further, in the washer type load cell and the thrust load detecting mechanism, the load cell main body has a plurality of pressure receiving portions arranged at predetermined intervals in the circumferential direction on one surface receiving the thrust load, and the pressure receiving portion And the support portion have different arrangement phases in the circumferential direction. With this configuration, the support portion functions as a fulcrum and the pressure receiving portion functions as an action point, and the distance between the action point and the fulcrum is set sufficiently long. Therefore, output sensitivity characteristics are improved as compared with the case where one side of the load cell body is pressed over the entire surface.

  In the washer type load cell and the thrust load detection mechanism, the load cell main body is sandwiched between the pressure receiving plates from both sides. With this configuration, the load cell body is less likely to slip in the radial direction. Therefore, hysteresis can be minimized.

  Moreover, in the said thrust load detection mechanism, the said bearing is comprised by a pair of angular ball bearing arrange | positioned combining a back surface. Since this angular ball bearing has a contact angle, it can simultaneously support a radial load and a thrust load. Therefore, the thrust load can be reliably transmitted to the load cell body.

  In the thrust load detection mechanism, the shaft is configured such that both ends thereof are supported by cylindrical roller bearings. This cylindrical roller bearing has high rigidity against a radial load. Therefore, the shaft is not affected by the radial load, and the thrust load is accurately detected.

It is a longitudinal cross-sectional view which shows a thrust load detection mechanism. It is a perspective view which shows the surface of a load cell main body in a washer type load cell. It is a perspective view which shows the back surface of a load cell main body in a washer type load cell.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a thrust load detection mechanism. In this thrust load detection mechanism 1, both ends of the rotating shaft 2 are rotatably supported by a pair of cylindrical roller bearings 3 and 4 having a load capability with respect to a radial load.

  Between the pair of cylindrical roller bearings 3, 4, as an example of a bearing described in the claims, a pair of angular ball bearings 5, 6 arranged in combination with the back surface are interposed, and the rotating shaft 2 is disposed. It is supported rotatably. Since the angular ball bearings 5 and 6 have a contact angle, they can simultaneously support a radial load and a thrust load. Furthermore, a washer-type load cell 10 is inserted into the rotary shaft 4 via a collar 7 between the upper cylindrical roller bearing 3 and the lower angular ball bearing 5.

  The washer-type load cell 10 has the configuration shown in FIGS. 2 and 3 and includes a load cell body 11 having an annular shape. As shown in FIG. 2, support portions 12, 13, 14, and 15 are formed on one side (front surface) of the load cell main body 11 at positions that divide the circumference into four equal parts. That is, the load cell body 11 is formed with doubly supported beams 16, 17, 18, 19 having the support portions 12 and 13, 13 and 14, 14 and 15, or 15 and 12 as fixed ends. With this configuration, the load cell main body 11 is configured to be distorted with the support portions 12, 13, 14, 15 as fulcrums according to the thrust load that presses the other side (back surface). In the present embodiment, the support portions 12, 13, 14, and 15 are provided so as to divide the circumference into four equal parts. However, the support parts are not limited to the four equal parts and are divided into three equal parts or five etc. The structure which provides a support part so that it may be divided may be sufficient.

  Further, on one side of the load cell body 11, protrusions 20, 21, 22, and 23 are formed at intermediate positions between the adjacent support portions 12 and 13, 13 and 14, 14 and 15, or 15 and 12. ing. The protrusions 20, 21, 22, 23 are formed thinner than the support parts 12, 13, 14, 15. With this configuration, when a thrust load exceeding the limit stress is applied to the load cell main body 11, before the load cell main body 11 is broken, the protrusions 20, 21, 22, and 23 come into contact with a pressure receiving plate described in detail later. Prevent distortion deformation.

  On the other side of the load cell main body 11, as shown in FIG. 3, pressure receiving portions 24, 25, 26, and 27 are formed at positions that divide the circumference into four equal parts. The pressure receiving portions 24, 25, 26, and 27 are disposed behind the protrusions 20, 21, 22, and 23, and the arrangement phase in the circumferential direction is different from that of the support portions 12, 13, 14, and 15. With this configuration, the load cell main body 11 is configured such that the intermediate positions of the doubly supported beams 16, 17, 18, 19 are pressed and distorted from the corresponding pressure receiving portions 20, 21, 22, 23.

  Further, as shown in FIG. 2, the load body 11 is sandwiched between pressure receiving plates 30 and 31 from both sides thereof. The pressure receiving plates 30 and 31 have an annular shape and are inserted into the rotary shaft 2. One pressure receiving plate 30 is fixed to the support portions 12, 13, 14, 15 with screws 12 s, 13 s, 14 s, 15 s, and the other pressure receiving plate 31 also has the pressure receiving portions 24, 25, 26, 27 are fixed with screws 24s, 25s, 26s, 27s.

  The pressure receiving plate 30 is interposed between the load cell main body 11 and the cylindrical roller bearing 3, and the upper surface contacts the lower surface of the outer ring of the cylindrical roller bearing 3, while the lower surface supports the support portions 12 and 13 of the load cell main body 11. , 14 and 15 so as to be in contact with the rotary shaft 5. The other pressure receiving plate 31 is interposed between the load cell main body 11 and the angular ball bearing 5, and the upper surface contacts the pressure receiving portions 24, 25, 26, 27 of the load cell main body 11, while the lower surface is angular. The ball bearing 5 is inserted into the rotating shaft 5 so as to be in contact with the upper surface of the outer ring.

  As shown in FIGS. 2 and 3, a total of eight strain gauges 40, 41, 42, 43, 44, 45, 46, and 47, which are examples of strain detection means, are attached to both surfaces of the load cell body 11. is there. The strain gauges 40, 41, 42, 43, 44, 45, 46, 47 are affixed to both surfaces of the doubly supported beams 16, 17, 18, 19 and detect the strain of the load cell body 11 as an electrical signal. . Then, the amount of strain is calculated from the sum of these electric signals, and the thrust load is detected.

  Further, a wave washer 50 as an example of an elastic member is interposed between the angular ball bearing 6 and one cylindrical roller bearing 4. The wave washer 50 is configured so that a gap is not generated between the components by applying preload to the above-described components inserted into the rotary shaft 4. Here, both sides of the wave washer 50 have a wave shape and are configured to be elastically deformable. Instead of the wave washer 50, rubber packing may be used as an example of an elastically deformable component.

  Hereinafter, the transmission path of the thrust load acting on the rotating shaft 4 will be described. The arrow of the one-dot chain line shown in FIG. 1 shows the transmission path of the thrust load. First, when a thrust load is applied to the rotating shaft 4, the flange portion 2 a of the rotating shaft 4 presses the inner ring of the cylindrical roller bearing 3. A thrust load is transmitted from the inner ring to the inner ring of the adjacent angular ball bearing 6 via the wave washer 29. Here, in the angular ball bearings 5 and 6, the balls and the inner ring and the outer ring have contact angles. Therefore, the thrust load transmitted to the inner ring is reliably transmitted to the outer ring through the balls by arranging the back surfaces of the two angular ball bearings 5 and 6 in combination.

  Subsequently, the thrust load transmitted to the outer ring of the angular ball bearing 5 is transmitted to the support portions 12, 13, 14, 15 of the load cell body 11 via the pressure receiving plate 31. In response to this, the protrusions 16, 17, 18, 19 formed on the load cell body 11 press the receiving member 20. Therefore, the load cell body 11 is distorted with the protrusions 16, 17, 18, 19 as fulcrums. That is, in the load cell main body 11, the adjacent protrusion 16 and protrusion 17, the protrusion 17 and protrusion 18, and the protrusion 18 and protrusion 19 function as a beam, and distortion occurs in this beam.

  Here, the second protrusions 21, 22, 23 and 24 are formed on one surface of the load cell main body 11. Accordingly, when a thrust load exceeding the limit stress is applied to the load cell main body 11, the second protrusions 21, 22, 23, and 24 come into contact with the pressure receiving plate 30. Therefore, the load cell main body 11 is protected from being damaged by an overload of the thrust load.

  As described above, in the thrust load detection mechanism 1 of the present invention, the rotating shaft 4 is rotatably supported by the pair of cylindrical roller bearings 3 and 4. These cylindrical roller ball bearings 3 and 4 have a load capacity against a radial load acting on the rotary shaft 2. In addition, by arranging the back surfaces of the angular ball bearings 5 and 6 in combination, the thrust load is reliably transmitted to the outer ring as shown by the one-dot chain line shown in FIG. Therefore, since the thrust load is reliably transmitted to the washer type load cell 10 without being affected by the radial load, the thrust load acting on the rotating shaft 2 can be detected with high accuracy.

  In the washer type load cell 10 of the present invention, the distance between the support parts 12, 13, 14, 15 and the pressure receiving parts 24, 25, 26, 27, that is, the distance between the fulcrum and the action point is sufficiently long. The configuration can be set. As a result, the output sensitivity characteristic is improved, and particularly the detection accuracy of the low thrust load is excellent.

  Further, in the configuration in which the beam is formed in the width direction of the load cell main body 11 as in the washer type load cell described in the prior art, the inner ring and the outer ring of the load cell main body 11 serve as both support ends of the beam, and the strain gauge is attached. This gets in the way. In particular, the smaller the device, the narrower the distance between the inner ring and the outer ring, and the more difficult the pasting work becomes. On the other hand, in the washer type load cell 10 of the present invention, the doubly supported beams 16, 17, 18, 19 are formed in the circumferential direction. Therefore, a sufficient space for attaching the strain gauges 40 to 47 is secured. Therefore, the work of attaching the strain gauges 40 to 47 becomes easy, and the thickness of the main body can be reduced.

  Further, when the washer type load cell 10 is actually inserted into the rotating shaft 2 to detect the thrust load, one side of the load cell main body 11 is not pressed evenly due to the inclination of the rotating shaft 2 or the like. For this reason, the load cell body 11 is distorted unevenly. However, in the conventional configuration in which the beam is formed in the width direction of the load cell body, in order to detect non-uniform strain, it is necessary to attach a strain gauge over the entire surface and detect the strain from the sum of these. There is. On the other hand, in the washer type load cell 10 of the present invention, since the beams 16, 17, 18, 19 are formed in the circumferential direction, even the non-uniform strain is distorted by the number of beams. If a gauge is attached, distortion can be detected from the sum of these electrical signals.

  In the washer type load cell of the present invention, the load cell body 11 is sandwiched between the pressure receiving plates 30 and 31 from both sides. Moreover, by fixing these with the screws 12s, 13s, 14s, 15s and 24s, 25s, 26s, 27s, the load cell body 11 is less likely to slip in the radial direction. Therefore, hysteresis can be minimized in the stage of applying a thrust load to the load cell main body 11 and the stage of reducing this load.

DESCRIPTION OF SYMBOLS 1 Thrust load detection mechanism 2 Rotating shaft 2a Flange part 3, 4 Cylindrical roller bearing 5, 6 Angular contact ball bearing 7 Collar 10 Washer type load cell 11 Load cell main body 12, 13, 14, 15 Support part 12s, 13s, 14s, 15s Screw 16 , 17, 18, 19 Double-supported beams 20, 21, 22, 23 Protrusions 24, 25, 26, 27 Pressure receiving portions 24s, 25s, 26s, 27s Screws 30, 31 Pressure receiving plates 40, 41, 42, 43, 44, 45, 46, 47 Strain gauge 50 Wave washer

Claims (6)

A bearing that rotatably supports the shaft and receives a thrust load acting on the shaft;
A load cell main body that is inserted into the shaft and is distorted by being pressed by the bearing, and a washer-type load cell comprising a strain detection means for detecting a strain amount of the load cell main body,
A pressure receiving plate interposed between the bearing and the washer-type load cell, and transmitting a thrust load acting on the bearing to the washer-type load cell;
A thrust load detection mechanism comprising: The thrust load detection mechanism according to claim 1, wherein the load cell main body includes a plurality of protrusions on both surfaces or one surface, and is distorted with the protrusions serving as fulcrums. 3. The thrust load detection mechanism according to claim 1, wherein the pressure receiving plate is a pair so as to sandwich the washer type load cell from both sides. The thrust load detecting mechanism according to any one of claims 1 to 4, wherein the bearings are a pair of angular ball bearings arranged in combination with a back surface. 6. The thrust load detection mechanism according to claim 1, wherein both ends of the shaft are rotatably supported by cylindrical roller bearings. The thrust load detecting mechanism according to any one of claims 1 to 6, wherein the bearing is urged by an elastic member in a direction in which the washer-type load cell is pressed.

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