TWI470237B - Potentiometer - Google Patents

Description

Potentiometer

This invention relates to a potentiometer provided with an automatic return mechanism having a rotating shaft, which is used for position detection in various machines.

The first example is a conventional example of such a potentiometer, and is an exploded perspective view showing the potentiometer described in Patent Document 1.

In Fig. 1, reference numeral 11 denotes a slider holder, and a boss portion 11b is protruded from a central portion of the bottom plate 11a, and the shaft portion 11c is formed upward and downward from the center portion. A pair of restriction walls 11d, 11e are erected at a predetermined angle on the outer circumference of the bottom plate 11a.

12 is a spiral coil spring having a stacking portion 12a that winds a plurality of turns of the hub portion 11b, and an upper bent portion 12b and a lower bent portion 12c at the liberation end, 13 is a casing that houses the slider seat 11, and a casing The body 13 has a notch portion 13a, and both side edges of the notch portion 13a serve as spring seats 13b and 13c.

14 is a slider fixed to the lower surface of the slider holder 11, and 15 is an insulating substrate fixed to the open surface of the casing 13. A resistor pattern 15a for sliding the slider 14 is formed on the upper surface of the insulating substrate 15.

The shaft portion 11c above the slider holder 11 is supported by the hole portion 13d of the casing 13, and the lower shaft portion 11c is supported by the hole portion 15b of the insulating substrate 15. As shown in Fig. 2, the upper bent portion 12b of the helical coil spring 12 is spring-locked by the spring seat 13b and the regulating wall 11d, and the lower bent portion 12c is biased by the spring seat 13c and the regulating wall 11e.

In the potentiometer, when the shaft portion 11c is rotated in the counterclockwise direction from the stationary state of Fig. 2, as shown in Fig. 3, the left restricting wall 11e of the slider holder 11 overcomes the elasticity of the coil spring 12. The lower bent portion 12c of the helical coil spring 12 is pressed in the counterclockwise direction, and the upper bent portion 12b of the helical coil spring 12 is locked to the spring seat 13b of the casing 13, and the regulating wall 11d is rotated in the counterclockwise direction. During the period, the slider 14 slides in the counterclockwise direction on the resistor pattern 15a, and the desired output signal is obtained by changing the resistance value.

When the rotational force of the shaft portion 11c is removed, the lower bending portion 12c is pressed in the clockwise direction by the elastic restoring force of the helical coil spring 12, and the slider seat 11 and the helical coil spring 12 return to the second. The original stationary state of the graph.

Similarly, when the shaft portion 11c is rotated in the clockwise direction from the stationary state of FIG. 2, the right restricting wall 11d of the slider holder 11 presses the upper bent portion 12b of the helical coil spring 12, and the helical coil spring 12 The lower bent portion 12c is thus locked to the spring seat 13c of the casing 13, and the regulating wall 11e is rotated in the clockwise direction. Thereby, the slider 14 slides in the clockwise direction on the resistor pattern 15a to obtain a desired output signal.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1]

Japanese Utility New Case Registration No. 2533523

In the potentiometer of the above configuration, the end faces of the regulating walls 11d and 11e provided in the slider holder 11 and the end faces of the spring seats 13b and 13c provided in the casing 13 are all flat, so the coil spring 12 is The upper bent portion 12b or the lower bent portion 12c, the contact with the restricting walls 11d, 11e, and the spring seats 13b, 13c are substantially in line contact.

On the other hand, the end faces of the restricting walls 11d and 11e and the end faces of the spring seats 13b and 13c are, for example, in the stationary state (neutral state) of Fig. 2 due to dimensional tolerances and the like, the faces are not surely coincident, that is, they are generated. The interval between the pair of restriction walls 11d, 11e is wider than the interval between the pair of spring seats 13b, 13c or the opposite state.

In the case where the interval between the pair of regulating walls 11d and 11e is wider than the interval between the pair of spring seats 13b and 13c, the upper bent portion 12b and the lower bent portion 12c of the helical coil spring 12 are shown in FIG. The neutral position produces a state in which only the spring seats 13b, 13c are in elastic contact with each other, and there is no contact with the restricting walls 11d, 11e, and the interval between the pair of restricting walls 11d, 11e opposite thereto is longer than the pair of spring seats 13b. When the interval between 13c is narrower, the upper bent portion 12b and the lower bent portion 12c are elastically contacted only by the restricting walls 11d and 11e without coming into contact with the spring seats 13b and 13c.

In this state, the upper bent portion 12b or the lower bent portion 12c and the restricting walls 11d and 11e and the spring seats 13b and 13c are in line contact with each other. Therefore, the upper bent portion 12b and the lower bent portion are defined by the line contact. The direction in which the folded portion 12c extends, that is, the reason for limiting the deflection. On the other hand, if such a state occurs, the rotation of the shaft portion 11c is not completely restricted at the neutral position, and sway is generated, which causes a decrease in detection accuracy.

SUMMARY OF THE INVENTION An object of the present invention is to provide a potentiometer which does not cause rattling of a rotating shaft even in a neutral position, and is excellent in detection accuracy.

According to the invention, the substrate in which the resistor pattern is formed, the rotor in which the slider that is in sliding contact with the resistor pattern is fixed, and the spiral coil spring are housed in the housing; and the rotation of the coil coil spring is coupled to the rotor. a shaft, a potentiometer protruding from the housing, and a rotor having a pair of spring guiding portions surrounding the helical coil spring and having an outer diameter along the outer diameter of the helical coil spring; the spiral coil spring is derived in a diameter direction The both end portions are elastically contacted with the circumferential end faces of the spring seat projecting from the circumferential end faces of the spring guide portion of one of the pair of spring guide portions and the inner circumferential surface of the case, one of which Both end faces in the circumferential direction of the spring guide portion and both end faces in the circumferential direction of the spring seat are formed to be in point contact with both end portions of the coil spring.

Both ends of the helical coil spring that automatically returns the rotating shaft are in contact with both end faces of the spring guiding portion of the rotor and both end faces of the spring seat of the casing. Therefore, for example, even in the neutral position due to the dimensional tolerance, the both end faces of the spring guiding portion do not coincide with the end faces of the spring seat, and unlike the conventional wire contact configuration, the shape of both end portions of the helical coil spring is not limited. In the case where the deflection is expected, that is, by bending the both end portions, it is possible to obtain a state in which both end portions of the spiral coil spring are in elastic contact with both the spring guide portion of the rotor and the spring seat of the casing. According to this invention, it is possible to prevent the rotor of the neutral position and the rotating shaft from being shaken, thereby obtaining a potentiometer excellent in detection accuracy.

The embodiment will be described with reference to the embodiments of the invention.

4A and 4B are views showing an appearance of an embodiment of the potentiometer of the present invention, and Figs. 5A and 5B are sectional views showing the structure. Fig. 6 is a diagram showing the decomposition of each part.

The casing 20 has a cylindrical base body 21, and a square-shaped plate portion 22 is formed on the back surface side of the base body 21 from the outer peripheral surface thereof, and a flange-like shape is formed on the front surface side of the base body 21 from the outer peripheral surface thereof in opposite directions. A pair of mounting portions 23 are largely protruded from the ground. A stepped cylindrical portion 24 is formed to protrude from the front surface of the base body 21.

A bearing 31 is housed in the cylindrical portion 24 of the casing 20, and a metal sleeve 32 is housed in each of the sleeve holes 23a of the pair of mounting portions 23. The casing 20 and the bearing 31 are respectively made of synthetic resin. In this example, the bearing 31 and the sleeve 32 are insert-molded in the casing 20. The case 20 and the bearing 31 are made of synthetic resin, and a resin having high rigidity and excellent flame retardancy can be used for the case 20, and a resin excellent in abrasion resistance can be used for the bearing 31.

The rotor 40 has a plate portion 41 and a pair of spring guide portions 42, 43 which are formed to protrude from one surface of the plate portion 41, and are made of synthetic resin. The pair of spring guiding portions 42, 43 are respectively formed in a circular arc shape, and the circular arcs are located on the same circumference. The plate portion 41 is formed in a disk shape, and a portion on the outer peripheral side of one of the spring guiding portions 43 is formed in a notch shape.

The rotating shaft 33 is made of metal, and an elliptical portion 33a is formed at one end portion thereof, and a shaft portion 33b having a small diameter is formed to protrude from the front end surface of the oblong portion 33a. The long elliptical portion 33a of the rotary shaft 33 is fitted into the plate portion 41 of the rotor 40, and is integrated with the rotor 40, and is located at the center of the arc of the spring guide portions 42, 43. The shaft portion 33b formed on the front end surface of the oblong 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. 7, the back surface of the plate portion 41 is formed with a push nut press-fitting portion 44, a heat-screwing portion 45, and a guide portion 46. The slider 34 is made of a metal having elasticity, and is formed by a pressing nut portion 34a, a caulking hole 34b, and a notch 34c. The pressing nut portion 34a of the slider 34 is press-fitted into the pressing nut press-fitting portion 44 of the rotor 40, and the heat caulking portion 45 of the rotor 40 is inserted into the caulking hole 34b, and the sliding member is subjected to heat caulking treatment. 34 is mounted and fixed to the rotor 40. 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 portion when the slider 34 is assembled.

The helical coil spring 35 is inserted into the rotating shaft 33 and housed in a space in the pair of spring guiding portions 42 and 43 of the rotor 40. The pair of spring guiding portions 42, 43 surround the helical coil spring 35 along the outer diameter of the helical coil spring 35, whereby the helical coil spring 35 is externally held by the pair of spring guiding portions 42, 43.

The rotating shaft 33 is inserted into the hole portion 31a of the bearing 31 to be axially supported, and the bearing 31 is insert-molded into the casing 20. In the cylindrical portion 24 of the casing 20, a tip seal portion 36 is disposed outside the bearing 31, and a gasket 37 and an E-ring 38 for restricting the movement of the tip seal portion 36 are disposed. The E-ring 38 is fitted in an E-ring insertion groove 33c provided in the rotating shaft 33. The front side of the housing 20 is sealed by a tip seal 36.

The substrate 50 is attached to the opening on the back side of the base 21 of the casing 20 . The substrate 50 is composed of an annular portion 51 and a protruding portion 52 that protrudes from a part of the outer circumference thereof. In the annular portion 51, a pair of resistor patterns 53 and 54 which are formed in an arc shape are formed concentrically, and are formed to be connected to both ends of the resistor patterns 53 and 54 and pass through the annular portion 51. The conductor patterns 55 to 57 reach the front end of the protruding portion 52. The resistor patterns 53 and 54 are formed by, for example, 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 through the substrate 50 at the tips of the respective conductor patterns 55 to 57, and the terminals 61 are caulked to the terminal insertion holes 58. In Fig. 6, the caulking portion 61a of the terminal 61 is a shape which is shown as a caulking process.

The substrate 50 is press-fitted into the base 21 of the casing 20, and is received by abutting against the abutting portion 21a provided in the base 21. Thereby, the slider 34 attached to the rotor 40 is pressed against the resistor patterns 53, 54. On the back side of the plate portion 41 of the rotor 40, the ring portion 33b is surrounded by a ring shape. The portion 47 is located in the opening 59 of the substrate 50.

A casing 62 is attached to the opening on the back side of the base 21 of the casing 20 again. The outer casing 62 is fixed by heat caulking the heat caulking portion 21b provided in the base 21 of the casing 20. A bearing hole 62a for axially supporting the shaft portion 33b formed at the tip end of the rotating shaft 33 is formed on the inner surface of the outer casing 62, and the shaft portion 33b is axially supported by the bearing hole 62a.

As shown in FIGS. 5A and 5B, around the outer casing 62 attached to the casing 20, the adhesive 63 is applied and filled, thereby sealing the back side of the casing 20. In this example, a space portion is provided in a portion of the casing 20 at a position of the terminal 61, and an adhesive 63 is filled around the terminal 61 and around the caulking portion 61a as shown in Fig. 5B. Thereby, the terminal 61 is firmly fixed, and displacement between the terminals 61 can be prevented. In addition, in the case where the terminal 61 is formed by, for example, performing tin plating treatment on carbon steel, growth of tin-plated tin whiskers can be prevented.

Next, the position and the locked state in the casing 20 of the both end portions 35a and 35b which are led out in the radial direction of the helical coil spring 35 will be described with reference to Figs. 8A and 8B.

8A and 8B are views showing a state in which the rotating shaft 33 is at the neutral position, and both end portions 35a and 35b of the coil spring 35 elastically contact the circumferential end faces 43a and 43b of the spring guiding portion 43 of the rotor 40, The elastic contact is formed in the circumferential direction at both end faces 25a and 25b of the spring seat 25 provided on the inner circumferential surface of the casing 20 in an arc shape.

Both end portions 35a and 35b of the coil spring 35 and both end faces 43a and 43b of the spring guide portion 43 and both end faces 25a and 25b of the spring seat 25 are formed in contact with each other in a point contact manner. In this example, the respective ends of the end portions 35a, 35b of the coil spring 35 are in point contact with the end faces 25a, 25b of the spring seat 25, between the end face 35a and the end face 25a, and between the end portion 35b and the end face 25b. A wedge-shaped space that expands toward the center of the rotor 40, respectively. On the other hand, the end faces 43a, 43b of the spring guide portion 43 are in point contact with the end portions 35a, 35b of the coil springs 35 at the inner peripheral side corner portions thereof, between the end faces 35a and the end faces 43a, and at the end portions. Between 35b and the end surface 43b, a wedge-shaped space that expands toward the outer peripheral side of the rotor 40 is formed.

Since both end faces 43a and 43b of the spring guide portion 43 and both end faces 25a and 25b of the spring seat 25 are formed in a point contact point with the both end portions 35a and 35b of the coil spring 35, respectively, two of the coil springs 35 are provided. Since the end portions 35a and 35b are easily deflected, the end faces 43a and 43b of the spring guide portion 43 do not coincide with the end faces 25a and 25b of the spring seat 25 in a neutral state or the like, but the spiral is not coincident by the spiral. Both end portions 35a and 35b of the coil spring 35 are flexed, and the both end portions 35a and 35b of the coil spring 35 are elastically brought into contact with both the spring guiding portion 43 and the spring seat 25 to allow the rotor 40 and the rotating shaft to be rotated. 33 will not sway.

As in this example, a wedge-shaped space is formed between the end portions 35a and 35b of the coil spring 35, and both end faces 43a and 43b of the spring guide portion 43 and both end faces 25a of the spring seat 25 may be used. The inclined portion required for the 25b is provided, that is, the inclined surface is formed, and for example, a curved surface may be formed.

9A and 9B are views showing the state in which the rotary shaft 33 is rotated in the counterclockwise direction and the clockwise direction, respectively, and the spring guide portion 43 of the rotor 40 presses the end thereof against the elasticity of the coil spring 35 in Fig. 9A. In the portion 35B, in the Fig. 9B, the end portion 35b is pressed against the elasticity. The slider 34 is slid on the resistor patterns 53, 54 of the substrate 50 by the rotation of the rotor 40, and the desired output signal can be obtained from the terminal 61. When the rotational force of the rotary shaft 33 is released, the rotor 40 and the rotary shaft 33 return to the original neutral position shown in Fig. 8A by the elastic restoring force of the helical coil spring 35.

As described above, with this example, the sway of the rotating shaft 33 can be prevented at the neutral position. Further, since the helical coil spring 35 is held by the pair of spring guiding portions 42, 43 circumscribing the rotor 40, the shaft portion of the spring is not inclined, and unintended deformation does not occur, so that good rotation performance can be obtained.

This potentiometer is used, for example, for detecting the accelerator acceleration amount of the electric scooter or the Scooter.

11. . . Sliding seat

12. . . Spiral coil spring

13. . . case

14. . . Slide

15. . . Insulating substrate

20. . . case

twenty one. . . Matrix

twenty two. . . Square shape plate

twenty three. . . Installation department

twenty four. . . Cylinder

25. . . Spring seat

31. . . Bearing

32. . . Sleeve

33. . . Rotary axis

34. . . Slide

35. . . Spiral coil spring

36. . . Tip seal

37. . . Gasket

38. . . E-ring

40. . . Rotor

41. . . Board

42, 43. . . Spring guide

44. . . Push nut press-in part

45. . . Hot caulking

46. . . Guide

47. . . Ring

50. . . Substrate

51. . . Ring

52. . . Protruding

53, 54, . . Resistor pattern

55-57. . . Conductor pattern

58. . . Terminal insertion hole

59. . . Opening

61. . . Terminal

62. . . shell

63. . . Adhesive

Fig. 1 is an exploded perspective view of a conventional potentiometer.

Fig. 2 is a cross-sectional view showing the stationary state (neutral position) of the potentiometer shown in Fig. 1.

Fig. 3 is a cross-sectional view showing the operation state of the potentiometer shown in Fig. 1.

Fig. 4A is a perspective view showing an embodiment of the potentiometer of the invention, and Fig. 4B is a front view thereof.

Fig. 5A is a cross-sectional view taken along line C-C of Fig. 4B, and Fig. 5B is a cross-sectional view taken along line D-D of Fig. 4B.

Fig. 6 is an exploded perspective view of the potentiometer shown in Fig. 4A.

Fig. 7 is a view for explaining the mounting of the slider to the rotor.

Fig. 8A is a cross-sectional view showing a state in which the rotating shaft is in the neutral position, and Fig. 8B is a partially enlarged view thereof.

9A is a cross-sectional view showing a state in which the rotation axis is rotated in the counterclockwise direction, and FIG. 9B is a cross-sectional view showing a state in which the rotation axis is rotated in the clockwise direction.

25. . . Spring seat

25a. . . End face

25b. . . End face

33. . . Rotary axis

35. . . Spiral coil spring

35a. . . End face

35b. . . End face

43. . . Spring guide

43a. . . End face

43b. . . End face

Claims (3)

A potentiometer characterized in that: in a casing, a substrate on which a resistor pattern is formed, a rotor to which a slider that is in sliding contact with the resistor pattern is fixed, and a coil spring are housed; and the coil spring is inserted And a rotating shaft coupled to the rotor, the potentiometer protruding from the housing, the rotor having a pair of spring guides that surround the spiral coil spring and have a cross-sectional arc shape along an outer diameter of the coil spring The both ends of the spiral coil spring which are led out in the radial direction are elastically contacted with the circumferential end faces of one of the pair of spring guiding portions and the inner peripheral surface of the casing Both end faces of the spring guide portion of the spring seat and the circumferential end faces of the spring seat are formed to be in point contact with both end portions of the coil spring. The potentiometer according to claim 1, wherein the respective distal ends of the spiral coil springs are in point contact with the circumferential end faces of the spring seat. In the potentiometer according to the first aspect of the invention, the circumferential end faces of the one of the spring guide portions are in point contact with the both end portions of the spiral coil spring at the inner peripheral side corner portions thereof.