JP5166363B2 - Potentiometer - Google Patents

Description

  The present invention relates to a potentiometer provided with an automatic return mechanism for a rotating shaft, which is used for detecting the position of various devices.

FIG. 7 shows an exploded perspective view of a potentiometer described in Patent Document 1 as a conventional example of this type of potentiometer.
In FIG. 7, reference numeral 11 denotes a slider receiver. A boss 11b projects from the center of the bottom plate 11a, and a shaft 11c is formed upward and downward from the center. A pair of regulating walls 11d and 11e are erected on the outer periphery of the bottom plate 11a while maintaining a predetermined angle.

12 is a torsion coil spring that surrounds the boss 11b, and has a multi-turn laminated portion 12a, and an upper bent portion 12b and a lower bent portion 12c at the open end, and 13 is a case that houses the slider receiver 11. The case 13 has a notch 13a, and both side edges of the notch 13a are spring receivers 13b and 13c.
Reference numeral 14 denotes a slider fixed to the lower surface of the slider receiver 11, and reference numeral 15 denotes an insulating substrate fixed to the open surface of the case 13. A resistor pattern 15 a on which the slider 14 slides is formed on the upper surface of the insulating substrate 15.

  The upper shaft 11 c of the slider receiver 11 is supported by the hole 13 d of the case 13, and the lower shaft 11 c is supported by the hole 15 b of the insulating substrate 15. As shown in FIG. 8, the upper bent portion 12b of the torsion coil spring 12 is elastically locked to the spring receiver 13b and the restriction wall 11d, and the lower bent portion 12c is elastically locked to the spring receiver 13c and the restriction wall 11e.

  In this potentiometer, when the shaft 11c is rotated counterclockwise from the stationary state of FIG. 8, the left regulating wall 11e of the slider receiver 11 twists the lower bent portion 12c of the torsion coil spring 12 as shown in FIG. The coil wall 12 is pressed counterclockwise against the elasticity of the coil spring 12, and the upper bent portion 12 b of the torsion coil spring 12 remains locked to the spring receiver 13 b of the case 13, and the regulating wall 11 d rotates counterclockwise. . In the meantime, the slider 14 slides counterclockwise on the resistor pattern 15a, and a desired output signal is obtained by changing the resistance value.

  Here, when the rotational force of the shaft 11c is removed, the lower bent portion 12c is pressed in the clockwise direction by the elastic restoring force of the torsion coil spring 12, and the slider receiver 11 and the torsion coil spring 12 are restored to the original stationary state shown in FIG. Return to the state.

  Similarly, when the shaft 11c is rotated clockwise from the stationary state of FIG. 8, the right regulating wall 11d of the slider receiver 11 presses the upper bent portion 12b of the torsion coil spring 12, and the torsion coil spring 12 While the lower bent portion 12c remains locked to the spring receiver 13c of the case 13, the regulating wall 11e rotates in the clockwise direction. Thereby, the slider 14 slides clockwise on the resistor pattern 15a, and a desired output signal is obtained.

Utility Model Registration No. 2533523

  By the way, in the potentiometer configured as described above, the end surfaces of the regulating walls 11d and 11e provided on the slider receiver 11 and the end surfaces of the spring receivers 13b and 13c provided on the case 13 are both flat. Therefore, the contact between the upper bent portion 12b and the lower bent portion 12c of the torsion coil spring 12 and the restriction walls 11d and 11e and the spring receivers 13b and 13c is basically a line contact.

  On the other hand, the end surfaces of the regulating walls 11d and 11e and the end surfaces of the spring receivers 13b and 13c may not be aligned with each other in a stationary state (neutral position) as shown in FIG. , 11e may be wider than the gap between the pair of spring receivers 13b, 13c, or vice versa.

  When the interval between the pair of regulating walls 11d and 11e is wider than the interval between the pair of spring receivers 13b and 13c, the upper bent portion 12b and the lower bent portion 12c of the torsion coil spring 12 are in the neutral position in FIG. Then, there occurs a state in which only the spring receivers 13b and 13c are elastically contacted but not in contact with the regulating walls 11d and 11e, and conversely, the interval between the pair of regulating walls 11d and 11e is a pair of spring receivers 13b and 13e. When the distance is smaller than the distance between 13c, the upper bent portion 12b and the lower bent portion 12c are in elastic contact with only the regulating walls 11d and 11e, and are not in contact with the spring receivers 13b and 13c.

  In such a state, the upper bent portion 12b and the lower bent portion 12c are in line contact with the regulating walls 11d and 11e and the spring receivers 13b and 13c. This is because the shape of the lower bent portion 12c in the extending direction is defined, that is, the bending is limited. When such a state occurs, the rotation of the shaft 11c is not completely regulated at the neutral position, and play occurs, and such play causes a decrease in detection accuracy.

  In view of the above-described problems, an object of the present invention is to provide a potentiometer having excellent detection accuracy by preventing backlash from occurring on a rotating shaft even in a neutral position.

  According to the first aspect of the present invention, the substrate on which the resistor pattern is formed, the rotor to which the slider that is in sliding contact with the resistor pattern is fixed, and the torsion coil spring are accommodated in the case. In the potentiometer, the rotating shaft that is inserted through the rotor and protrudes from the case, the rotor surrounds the torsion coil spring and includes a pair of spring guides having an arcuate cross section along the outer diameter of the torsion coil spring. Both ends of the springs that are led out in the radial direction are elastically contacted with both ends in the circumferential direction of one spring guide of the pair of spring guides and both ends in the circumferential direction of a spring receiver protruding from the inner peripheral surface of the case. Both end surfaces in the circumferential direction of the guide and both end surfaces in the circumferential direction of the spring receiver are formed in point contact with both end portions of the torsion coil spring.

  According to a second aspect of the present invention, in the first aspect of the present invention, both ends of the torsion coil spring are in point contact with both circumferential end surfaces of the spring bearing.

  In the invention of claim 3, in the invention of claim 1, both end surfaces in the circumferential direction of one spring guide are respectively point-contacted with both end portions of the torsion coil spring at the inner peripheral side corner portion.

  In the present invention, both end portions of the torsion coil spring for automatically returning the rotating shaft are in point contact with both end surfaces of the spring guide of the rotor and both end surfaces of the spring receiver of the case. Therefore, even if the both ends of the spring guide and the both ends of the spring receiver are not aligned at the neutral position due to, for example, dimensional tolerance, the shape of the ends of the torsion coil spring is not defined unlike the conventional line contact structure, Bending can be expected, that is, both ends of the torsion coil spring can be in good elastic contact with both the spring guide of the rotor and the spring receiver of the case. Thereby, according to this invention, the backlash of the rotor and the rotating shaft in the neutral position can be prevented, and a potentiometer excellent in detection accuracy can be obtained in this respect.

A is a perspective view showing an embodiment of a potentiometer according to the present invention, and B is a front view thereof. 1A is a cross-sectional view taken along line CC in FIG. 1B, and B is a cross-sectional view taken along line DD in FIG. 1B. The disassembled perspective view of the potentiometer shown in FIG. The figure for demonstrating the attachment to the rotor of a slider. A is a sectional view when the rotating shaft is in a neutral position, and B is a partially enlarged view thereof. A is a cross-sectional view in a state where the rotation shaft is fully rotated counterclockwise, and B is a cross-sectional view in a state where the rotation shaft is fully rotated in the clockwise direction. The exploded perspective view of the conventional potentiometer. Sectional drawing of the resting state (neutral position) of the potentiometer shown in FIG. Sectional drawing of the operation state of the potentiometer shown in FIG.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows the appearance of an embodiment of a potentiometer according to the present invention, and FIG. 2 shows its cross-sectional structure. FIG. 3 is an exploded view of each part.

  The case 20 has a cylindrical base 21, and a rectangular plate portion 22 is formed to protrude from the outer peripheral surface of the base 21 on the back side, and a pair of mounting portions 23 are provided on the front side of the base 21 from the outer peripheral surface. Largely protruding in a flange shape in opposite directions. Further, a stepped cylindrical portion 24 is formed on the front surface of the base 21 so as to protrude.

  A bearing 31 is accommodated in the cylindrical portion 24 of the case 20, and a metal sleeve 32 is accommodated in each sleeve hole 23 a of the pair of attachment portions 23. The case 20 and the bearing 31 are each made of synthetic resin. In this example, the bearing 31 and the sleeve 32 are insert-molded in the case 20. Both the case 20 and the bearing 31 are made of synthetic resin, but the case 20 is made of a resin having high rigidity and excellent flame retardancy, and the bearing 31 is made of a resin having excellent wear resistance.

  The rotor 40 includes a plate portion 41 and a pair of spring guides 42 and 43 that are formed to protrude from one surface of the plate portion 41, and is made of a synthetic resin. The pair of spring guides 42 and 43 each have an arc shape in cross section, and these arcs are positioned on the same circumference. The plate portion 41 has a disc shape, and a portion located on the outer peripheral side of one spring guide 43 is cut out.

  The rotary shaft 33 is made of metal, and an oval portion 33a is formed at one end thereof, and a small-diameter shaft 33b is projected from the tip surface of the oval portion 33a. The rotary shaft 33 is insert-molded in the plate portion 41 of the rotor 40 and the rotor shaft 40 is integrated with the rotor 40 and positioned at the center of the arc formed by the spring guides 42 and 43. The shaft 33b formed on the front end surface of the oval shaped portion 33a protrudes from the back side of the plate portion 41 of the rotor 40.

  A slider 34 is attached to the back side of the plate portion 41 of the rotor 40. As shown in FIG. 4, a push nut press-fitting portion 44, a heat caulking portion 45, and a guide portion 46 are formed on the back surface of the plate portion 41 so as to protrude. The slider 34 is made of a metal having spring properties, and has a push nut portion 34a, a caulking hole 34b, and a notch 34c. The push nut portion 34a of the slider 34 is press-fitted into the push nut press-fit portion 44 of the rotor 40, and the heat caulking portion 45 of the rotor 40 is inserted into the caulking hole 34b, thereby performing the heat caulking, whereby the slider 34 is moved to the rotor 40. Attached to and fixed. The guide portion 46 of the rotor 40 and the notch 34c of the slider 34 corresponding to the guide portion 46 function as a guide when the slider 34 is incorporated.

  The torsion coil spring 35 is inserted into the rotary shaft 33 and accommodated in a space in the pair of spring guides 42 and 43 of the rotor 40. The pair of spring guides 42, 43 surround the torsion coil spring 35 along the outer diameter of the torsion coil spring 35, so that the torsion coil spring 35 is held in contact with the pair of spring guides 42, 43.

  The rotary shaft 33 is inserted into and supported by a hole 31a of a bearing 31 that is insert-molded in the case 20. A lip seal 36 is disposed outside the bearing 31 in the cylindrical portion 24 of the case 20, and a washer 37 and an E ring 38 that restrict the movement of the lip seal 36 are disposed. The E-ring 38 is fitted into an E-ring insertion groove 33 c provided on the rotating shaft 33. The front side of the case 20 is sealed with a lip seal 36.

  A substrate 50 is attached to the back side opening of the base 21 of the case 20. The substrate 50 includes an annular portion 51 and a protruding portion 52 protruding in a square shape from a part of the outer periphery thereof. A pair of arcuate resistor patterns 53, 54 are formed concentrically on the annular portion 51, and are connected to both ends of each of the resistor patterns 53, 54 and protrude through the annular portion 51. Conductor patterns 55 to 57 reaching the tip of the portion 52 are formed. The resistor patterns 53 and 54 are formed, for example, by printing and baking a resin paste mixed with carbon particles, and the conductor patterns 55 to 57 are formed by printing and baking a silver paste.

  Terminal insertion holes 58 are formed at the tips of the conductor patterns 55 to 57 so as to penetrate the substrate 50, and terminals 61 are caulked and attached to the terminal insertion holes 58. In FIG. 3, the caulking portion 61a of the terminal 61 is shown as a shape after being caulked.

  The substrate 50 is press-fitted into the base 21 of the case 20 and is abutted against and accommodated by the abutting portion 21 a provided in the base 21. As a result, the slider 34 attached to the rotor 40 is pressed against the resistor patterns 53 and 54. A ring-shaped portion 47 that protrudes from the back side of the plate portion 41 of the rotor 40 so as to surround the shaft 33 b is positioned in the opening 59 of the substrate 50.

  A cover 62 is further attached to the back side opening of the base 21 of the case 20. The cover 62 is fixed by heat caulking a heat caulking portion 21 b provided in the base 21 of the case 20. A bearing hole 62a for bearing a shaft 33b formed at the tip of the rotary shaft 33 is formed on the inner surface of the cover 62, and the shaft 33b is supported by the bearing hole 62a.

  As shown in FIG. 2, an adhesive 63 is applied and filled around the cover 62 attached to the case 20, thereby sealing the back side of the case 20. Further, in this example, a space is provided in the portion where the terminal 61 is located inside the case 20, and the periphery of the terminal 61 and the periphery of the caulking portion 61a are filled with the adhesive 63 as shown in FIG. 2B. Thereby, the terminal 61 is firmly fixed, and migration between the terminals 61 can be prevented. In addition, when the terminal 61 is made of, for example, carbon steel plated with tin, the growth of tin-plated whiskers can be prevented.

  Next, the position and locking state in the case 20 of both end portions 35a and 35b led out in the radial direction of the torsion coil spring 35 will be described with reference to FIG.

  FIG. 5 shows a state in which the rotating shaft 33 is positioned at the neutral position. Both end portions 35a and 35b of the torsion coil spring 35 are elastically contacted with both circumferential end surfaces 43a and 43b of the spring guide 43 of the rotor 40. Further, it is elastically contacted with both end surfaces 25a, 25b in the circumferential direction of the spring receiver 25 projecting in an arc shape on the inner peripheral surface of the case 20.

  Both end portions 35a and 35b of the torsion coil spring 35, both end surfaces 43a and 43b of the spring guide 43, and both end surfaces 25a and 25b of the spring receiver 25 are in contact with each other by point contact. In this example, the ends 35a and 35b of the torsion coil spring 35 are point-contacted with the end surfaces 25a and 25b of the spring receiver 25, respectively, between the end portions 35a and 25a, and between the end portions 35b and 25b. A wedge-shaped space that extends toward the center of the rotor 40 is formed between them. On the other hand, the end surfaces 43a and 43b of the spring guide 43 are in point contact with the end portions 35a and 35b of the torsion coil spring 35 at the inner peripheral corners, respectively, and between the end portions 35a and the end surfaces 43a and the end portions 35b. A wedge-shaped space is formed between the end surface 43b and extends toward the outer periphery of the rotor 40.

  Thus, since both end surfaces 43a and 43b of the spring guide 43 and both end surfaces 25a and 25b of the spring receiver 25 are in point contact with the both end portions 35a and 35b of the torsion coil spring 35, the torsion coil spring 35 is provided. Both end portions 35a and 35b of the torsion coil spring 35 are easy to bend. Therefore, even if the both end surfaces 43a and 43b of the spring guide 43 and the both end surfaces 25a and 25b of the spring receiver 25 are not aligned in a neutral state due to dimensional tolerances or the like. Both end portions 35a and 35b are bent so that both end portions 35a and 35b of the torsion coil spring 35 are in good elastic contact with both the spring guide 43 and the spring receiver 25 so that the rotor 40 and the rotating shaft 33 are not loose. be able to.

  In this example, both ends 43a and 43b of the spring guide 43 and both ends 25a and 25b of the spring receiver 25 are formed so that a wedge-shaped space is formed between the ends 35a and 35b of the torsion coil spring 35. Is provided with a required inclination, that is, an inclined surface, but may be a curved surface, for example.

  6A and 6B show a state in which the rotary shaft 33 is rotated counterclockwise and clockwise, respectively, and the spring guide 43 of the rotor 40 is elastically made the end portion 35a of the torsion coil spring 35 in FIG. 6A. 6B, the end 35b is pressed against its elasticity. As the rotor 40 rotates, the slider 34 slides on the resistor patterns 53 and 54 of the substrate 50, and a desired output signal can be obtained from the terminal 61. When the rotational force of the rotating shaft 33 is released, the rotor 40 and the rotating shaft 33 return to the original neutral position shown in FIG. 5A by the elastic restoring force of the torsion coil spring 35.

  As described above, according to this example, the play of the rotating shaft 33 can be prevented at the neutral position. Further, since the torsion coil spring 35 is held in contact with the pair of spring guides 42 and 43 of the rotor 40, the axis of the spring does not tilt and unexpected deformation does not occur. Rotational performance can be obtained.

  This potentiometer is used for detecting the amount of accelerator depression in an electric cart or a scooter, for example.

Claims (3)

In the case, a substrate on which a resistor pattern is formed, a rotor on which a slider that is in sliding contact with the resistor pattern is fixed, and a torsion coil spring are housed, and the rotor is inserted through the torsion coil spring. A potentiometer with a coupled rotating shaft protruding from the case,
The rotor includes a pair of spring guides that surround the torsion coil spring and have a circular arc cross section along the outer diameter of the torsion coil spring;
Both end portions of the torsion coil spring that are led out in the radial direction are elastically contacted with both end surfaces in the circumferential direction of one spring guide of the pair of spring guides and both end surfaces in the circumferential direction of a spring receiver that protrudes from the inner peripheral surface of the case. And
The potentiometer according to claim 1, wherein both end surfaces in the circumferential direction of the one spring guide and both end surfaces in the circumferential direction of the spring receiver are in point contact with both end portions of the torsion coil spring. The potentiometer according to claim 1, wherein
The potentiometer according to claim 1, wherein both ends of the torsion coil spring are in point contact with both end surfaces in the circumferential direction of the spring receiver. The potentiometer according to claim 1, wherein
The potentiometer according to claim 1, wherein both end surfaces in the circumferential direction of the one spring guide are in point contact with both end portions of the torsion coil spring at the inner peripheral corners thereof.

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