阅读说明：本技术 一种滑动变阻器 (Sliding rheostat ) 是由 不公告发明人 于 2019-10-31 设计创作，主要内容包括：本发明属于变阻器技术领域,具体的说是一种滑动变阻器,该滑动变阻器包括支架、电阻线圈柱、导柱、金属抱箍片和滑动单元；滑动单元包括紧固螺栓、滑动块、二号螺栓、抵触片和弹片；紧固螺栓穿过滑动块并伸入滑动块内开设的空腔内,紧固螺栓外圈设有一号齿轮,且一号齿轮左右两端与二号螺栓上端设有的二号齿轮相互啮合,二号螺栓下单设有挤压片贴附在导柱外圈上；滑动块前后两端面固接弹片,弹片内侧面贴附有抵触片；通过膨胀块、一号绳索和一号螺栓之间的配合,实现导柱直径的变化；通过滑动单元,实现滑动块在导柱的紧固。(The invention belongs to the technical field of varistors, and particularly relates to a slide rheostat which comprises a bracket, a resistance coil column, a guide pillar, a metal hoop sheet and a sliding unit, wherein the resistance coil column is arranged on the bracket; the sliding unit comprises a fastening bolt, a sliding block, a second bolt, a contact piece and an elastic piece; the fastening bolt penetrates through the sliding block and extends into a cavity formed in the sliding block, a first gear is arranged on the outer ring of the fastening bolt, the left end and the right end of the first gear are meshed with a second gear arranged at the upper end of a second bolt, and an extrusion piece is arranged below the second bolt and attached to the outer ring of the guide pillar; the front end surface and the rear end surface of the sliding block are fixedly connected with elastic sheets, and the inner side surfaces of the elastic sheets are attached with contact sheets; the diameter of the guide pillar is changed by matching the expansion block, the first rope and the first bolt; through the sliding unit, realize the fastening of sliding block at the guide pillar.)

1. A slide rheostat comprises a bracket (1), a resistance coil column (2), a guide column (3), a metal hoop sheet (4) and a sliding unit (5); the resistance coil is characterized in that two ends of the resistance coil column (2) are fixedly connected with a support (1), the resistance coil column (2) on the inner side of the support (1) is connected with a metal hoop sheet (4), the guide pillar (3) and the resistance coil column (2) are arranged in parallel, and the guide pillar (3) is fixedly connected to the upper end of the support (1); the sliding unit (5) is connected on the guide post (3) in a sliding way; the method is characterized in that: the interior of the guide post (3) is hollow, the middle 3/5 part of the guide post (3) is hollowed, and tapered expansion blocks (31) are respectively arranged at the left end and the right end of the interior of the guide post (3); the plane end of each expansion block (31) is fixedly connected to the two ends of the guide column (3) through a first spring (32), and the tip end of each expansion block (31) is fixedly connected to a first bolt (34) on the inner side of the two ends of the guide column (3) through a first rope (33); the sliding unit (5) comprises a fastening bolt (51), a sliding block (52), a second bolt (53), a collision sheet (54) and an elastic sheet (55); the fastening bolt (51) penetrates through the sliding block (52) and extends into a cavity (521) formed in the sliding block (52), a first gear (511) is arranged on the outer ring of the fastening bolt (51), the left end and the right end of the first gear (511) are meshed with a second gear (531) arranged at the upper end of a second bolt (53), and an extrusion piece (532) is arranged below the second bolt (53) and attached to the outer ring of the guide column (3); the front end face and the rear end face of the sliding block (52) are fixedly connected with elastic sheets (55), and contact sheets (54) are attached to the inner side faces of the elastic sheets (55); the diameter of the guide post (3) is changed by the cooperation of the expansion block (31), the first rope (33) and the first bolt (34); the slide block (52) is fastened to the guide post (3) by the slide unit (5).

2. A sliding varistor according to claim 1, wherein: the resistance coil column (2) is sleeved with a telescopic threaded ring (21), and two ends of the threaded ring (21) are respectively connected with the metal hoop sheet (4); the resistance coil is stabilized by the thread turns (21).

3. A sliding varistor according to claim 2, wherein: grooves (22) are symmetrically formed in the outer ring of the resistance coil column (2), and the resistance coil is tightly attached to the inner wall of each groove (22) when the resistance coil column (2) is wound; the resistance coil is tightly attached to the groove (22) for winding, so that the contact piece (54) can stably slide on the outer ring of the resistance coil column (2).

4. A sliding varistor according to claim 1, wherein: the elastic sheet (55) is connected with the abutting sheet (54) through a third bolt (551), one end of the third bolt (551) abuts against the abutting sheet (54), and the other end of the third bolt (551) penetrates through the elastic sheet (55) and is in threaded connection with the elastic sheet (55); the extrusion force of the contact piece (54) to the resistance coil is adjusted by rotating the third bolt (551).

5. A sliding varistor according to claim 4, characterized in that: the lower end of the contact piece (54) is provided with a strip-shaped bulge (541) which is attached to the groove (22); through the strip-shaped bulges (541), the accurate adjustment between the contact piece (54) and the resistance coil is realized.

6. A sliding varistor according to claim 5, characterized in that: a plurality of oval balls (542) are arranged in the middle of the bump (541), and the balls (542) are embedded in the bump (541); the friction between the contact piece (54) and the resistance coil is reduced by the balls (542).

Technical Field

The invention belongs to the technical field of varistors, and particularly relates to a sliding rheostat.

Background

A sliding varistor is a circuit element that can act as a control circuit by changing its resistance. In circuit analysis, the slide rheostat can be used as a constant value resistor or a variable value resistor. The slide rheostat generally comprises five parts, namely a binding post, a sliding sheet, a resistance wire, a metal rod, a porcelain cylinder and the like. The resistance wire of the slide rheostat is wound on an insulating porcelain cylinder, and insulating paint is coated outside the resistance wire.

The sliding rheostat is one of the common devices in electricity, and the working principle of the sliding rheostat is that the length of a resistance wire connected into a circuit part is changed to change the resistance, so that the current in the circuit is gradually changed. The resistance wire of the slide rheostat is generally nickel-chromium alloy with high melting point and large resistance, and the metal rod is generally metal with small resistance, so when the cross-sectional area of the resistance is fixed, the longer the resistance wire is, the larger the resistance is, the shorter the resistance wire is, and the smaller the resistance is.

Disclosure of Invention

In order to make up for the defects of the prior art and solve the problems of the looseness of the resistance coil on the resistance coil column and the unstable connection between the sliding block and the guide column, the invention provides a sliding rheostat.

The technical scheme adopted by the invention for solving the technical problems is as follows: the invention relates to a slide rheostat which comprises a bracket, a resistance coil column, a guide pillar, a metal hoop sheet and a sliding unit, wherein the resistance coil column is arranged on the bracket; the two ends of the resistance coil column are fixedly connected with a support, the resistance coil column on the inner side of the support is connected with a metal hoop sheet, the guide pillar is arranged in parallel with the resistance coil column, and the guide pillar is fixedly connected to the upper end of the support; the sliding unit is connected on the guide post in a sliding way; the interior of the guide post is hollow, the middle 3/5 part of the guide post is hollowed, and tapered expansion blocks are respectively arranged at the left end and the right end of the interior of the guide post; the plane end of each expansion block is fixedly connected to the two ends of the guide pillar through a first spring, and the tip end of each expansion block is fixedly connected to a first bolt on the inner side of the two ends of the guide pillar through a first rope; the sliding unit comprises a fastening bolt, a sliding block, a second bolt, a contact piece and an elastic piece; the fastening bolt penetrates through the sliding block and extends into a cavity formed in the sliding block, a first gear is arranged on the outer ring of the fastening bolt, the left end and the right end of the first gear are meshed with a second gear arranged at the upper end of a second bolt, and an extrusion piece is arranged below the second bolt and attached to the outer ring of the guide pillar; the front end face and the rear end face of the sliding block are fixedly connected with elastic pieces, and abutting pieces are attached to the inner side faces of the elastic pieces; the diameter of the guide pillar is changed by matching the expansion block, the first rope and the first bolt; the sliding block is fastened on the guide post through the sliding unit; when the rheostat is used for a long time, the surface of the guide post is abraded, and when the sliding rheostat is used, the sliding block automatically slides, so that the measuring result of the rheostat is inaccurate; the expansion block can be rotated by rotating the first bolt and pulled by the first rope, then the expansion block is gradually close to the sliding block, the expansion block extrudes and expands the guide pillar in the sliding block, the guide pillar and the sliding block are extruded with each other, the sliding block is prevented from sliding on the guide surface automatically, and the measurement result is more accurate by using the slide rheostat; through rotatory fastening bolt, then fastening bolt's a gear revolve and drive No. two gear revolve on No. two bolts, No. two gear revolve then will extrude piece spiral rising and extrude the guide pillar outer lane, through the extrusion piece that the symmetry set up for the extrusion piece extrusion force evenly distributes on the guide pillar surface, can avoid guide pillar fretwork department to buckle because of the extrusion and warp.

Preferably, the telescopic thread ring is sleeved on the resistance coil column, and two ends of the thread ring are respectively connected with the metal hoop sheets; the resistance coil is stabilized through the thread ring; when the sliding rheostat is used, after the contact sheet repeatedly slides on the coil for a plurality of times, the resistance coils are loosened and are not tightly wound, and the measurement result is inaccurate when the sliding rheostat is used; the surface of the outer ring of the resistance coil column is sleeved with a threaded ring, so that the resistance coil is wound around the threaded ring, and the relaxation phenomenon between the resistance coils can be avoided; if twine the resistance wire of different diameters on the coil post, see the accessible and adjust the distance between two metal hoop pieces, when two metal hoop pieces apart from the increase, the screw thread distance between the interior screw thread circle increases, can twine the great resistance wire of diameter, when two metal hoop pieces apart from reducing, the screw thread distance between the interior screw thread circle reduces, can twine the less resistance wire of diameter, can be according to the resistance wire of the different diameters of requirement winding that uses slide rheostat.

Preferably, the outer ring of the resistance coil column is symmetrically provided with grooves, and the resistance coil is tightly attached to the inner wall of the groove when the resistance coil column is wound; the resistance coil is tightly attached to the groove for winding, so that the contact piece can stably slide on the outer ring of the resistance coil column; when the slide rheostat is used, if the sliding block rotates around the guide pillar, the sliding block can twist the guide pillar due to the fact that the guide pillar is hollowed out, the guide pillar is twisted and damaged, and the slide rheostat cannot be normally used; when the contact piece slides in the groove in the resistance coil column, the groove can restrict the forward and backward swing of the contact piece, so that the sliding block is limited to rotate around the guide pillar, and meanwhile, the resistance coil is tightly wound on the inner wall of the groove, so that the resistance coil can be further fastened, and the resistance coil is more closely attached together.

Preferably, the elastic sheet is connected with the abutting sheet through a third bolt, one end of the third bolt abuts against the abutting sheet, and the other end of the third bolt penetrates through the elastic sheet and is in threaded connection with the elastic sheet; the extrusion force of the contact piece on the resistance coil is adjusted by rotating the third bolt; when the sliding rheostat is used, after the contact piece and the elastic sheet are used for a long time, the original elasticity of the contact piece and the elastic sheet can be reduced, and the contact piece part can be effectively clamped on the surface of a resistance coil, so that the sliding rheostat cannot be normally used; increase the attached effect between contact and the resistance coil through rotatory No. three bolts, when adjusting No. three bolts, the distance between contact and the shell fragment crescent, the distance between contact and the resistance coil dwindles gradually simultaneously, and in the recess was extruded to last contact lower extreme, the contact once more can effectively contact with the resistance coil.

Preferably, the lower end of the contact sheet is provided with a strip-shaped bulge attached to the groove; the strip-shaped bulges realize the accurate adjustment between the contact piece and the resistance coil; during the use, in order to increase the contact effect of support contact piece and resistance coil for slide rheostat measuring result is more accurate, sets up the arch of bar form at the support contact piece lower extreme surface, and during arch and resistance coil surface contact, the arch can be attached on resistance coil surface, has avoided the emergence of support contact piece and resistance coil contact failure's problem.

Preferably, a plurality of oval balls are arranged in the middle of each protrusion, and the balls are embedded in the protrusions; the friction force between the abutting contact piece and the resistance coil is reduced through the ball; when the resistance coil is used, when the contact piece slides on the surface of the resistance coil, if the contact piece is adjusted, the extrusion force between the contact piece and the resistance coil is too large, so that the sliding block is difficult to slide on the guide pillar, and the abrasion on the surface of the resistance coil is accelerated; settle the ball at protruding middle part, reduce the frictional force that supports between contact and the resistance coil, reduce the wearing and tearing that support between contact and the resistance coil, simultaneously, support the contact and make a round trip to slide more smoothly on the resistance coil surface to make the sliding block more easily slide on the guide pillar surface.

The invention has the technical effects and advantages that:

1. according to the slide rheostat, the first rope is pulled by adjusting the first bolt, and then the expansion block is pulled by the first rope, so that the expansion block supports the guide pillar, the extrusion force between the guide pillar and the sliding block is increased, and the stability between the sliding block and the guide pillar is increased; drive No. two gears through adjusting fastening bolt for No. two bolt rotations increase the extrusion force between guide pillar and the extrusion piece, thereby realize the stability of sliding block on the guide pillar.

2. According to the slide rheostat, resistance wires with different diameters can be wound through the telescopic thread ring, and the resistance wires can be replaced according to the use requirement; the resistance wire is wound behind the thread circle, and the conflict piece makes a round trip to slide at resistance coil after, can avoid the emergence of the lax phenomenon between the resistance coil to measuring result is more accurate when making the rheostat that slides use.

Drawings

The invention is further described with reference to the following figures and embodiments.

FIG. 1 is a perspective view of the present invention;

FIG. 2 is a cross-sectional view of the present invention;

FIG. 3 is an enlarged view of a portion of FIG. 2 at A;

FIG. 4 is a side cross-sectional view of the present invention;

FIG. 5 is a partial enlarged view at B in FIG. 4;

FIG. 6 is an enlarged view of a portion of FIG. 4 at C;

in the figure: the device comprises a bracket 1, a resistance coil column 2, a threaded ring 21, a groove 22, a guide column 3, an expansion block 31, a first spring 32, a first rope 33, a first bolt 34, a metal hoop sheet 4, a sliding unit 5, a fastening bolt 51, a first gear 511, a sliding block 52, a cavity 521, a second bolt 53, a second gear 531, an extrusion sheet 532, an interference sheet 54, a protrusion 541, a ball 542, an elastic sheet 55 and a third bolt 551.

Detailed Description

In order to make the technical means, the creation features, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the following embodiments.

As shown in fig. 1 to 6, the slide rheostat of the present invention comprises a support 1, a resistance coil column 2, a guide pillar 3, a metal hoop sheet 4 and a sliding unit 5; the two ends of the resistance coil column 2 are fixedly connected with a support 1, the resistance coil column 2 on the inner side of the support 1 is connected with a metal hoop sheet 4, a guide pillar 3 is arranged in parallel with the resistance coil column 2, and the guide pillar 3 is fixedly connected to the upper end of the support 1; the sliding unit 5 is connected on the guide post 3 in a sliding way; the interior of the guide post 3 is hollow, the middle 3/5 part of the guide post 3 is hollowed, and tapered expansion blocks 31 are respectively arranged at the left end and the right end of the interior of the guide post 3; the plane end of each expansion block 31 is fixedly connected to the two ends of the guide post 3 through a first spring 32, and the tip end of each expansion block 31 is fixedly connected to a first bolt 34 on the inner side of the two ends of the guide post 3 through a first rope 33; the sliding unit 5 comprises a fastening bolt 51, a sliding block 52, a second bolt 53, an abutting sheet 54 and an elastic sheet 55; the fastening bolt 51 penetrates through the sliding block 52 and extends into a cavity 521 formed in the sliding block 52, a first gear 511 is arranged on the outer ring of the fastening bolt 51, the left end and the right end of the first gear 511 are meshed with a second gear 531 arranged at the upper end of a second bolt 53, and an extrusion piece 532 is singly arranged below the second bolt 53 and attached to the outer ring of the guide post 3; the front end face and the rear end face of the sliding block 52 are fixedly connected with elastic pieces 55, and contact pieces 54 are attached to the inner side faces of the elastic pieces 55; the diameter of the guide column 3 is changed through the cooperation of the expansion block 31, the first rope 33 and the first bolt 34; the sliding block 52 is fastened on the guide post 3 through the sliding unit 5; when the rheostat is used, after the rheostat is used for a long time, the surface of the guide post 3 is abraded, and when the sliding rheostat is used, the sliding block 52 automatically slides, so that the measuring result of the rheostat is inaccurate; the first bolt 34 can be rotated, the first bolt 34 is rotated, the expansion block 31 is pulled through the first rope, then the expansion block 31 is gradually close to the sliding block 52, then the expansion block 31 extrudes and expands the guide post 3 in the sliding block 52, the guide post 3 and the sliding block 52 are extruded with each other, the sliding block 52 is prevented from sliding on the guide surface, and the measuring result of the slide rheostat is more accurate; through rotatory fastening bolt 51, then fastening bolt 51's a gear 511 rotates and drives No. two gears 531 on No. two bolts 53 and rotate, and No. two gears 531 rotates and extrudees guide pillar 3 outer lane with extrusion piece 532 spiral rising after that, through the extrusion piece 532 that the symmetry set up for extrusion piece 532 extrusion force evenly distributes on the surface of guide pillar 3, can avoid guide pillar 3 fretwork department because of the extrusion buckling deformation.

As a specific embodiment of the present invention, a retractable threaded ring 21 is sleeved on the resistance coil column 2, and two ends of the threaded ring 21 are respectively connected with the metal hoop sheet 4; the resistance coil is stabilized through the thread ring 21; when the sliding rheostat is used, after the contact piece 54 repeatedly slides on the coil for a plurality of times, the resistance coils are loosened and are not tightly wound, and the measurement result is inaccurate when the sliding rheostat is used; the surface of the outer ring of the resistance coil column 2 is sleeved with a threaded ring 21, so that the resistance coil is wound around the threaded ring 21, and the phenomenon of looseness among the resistance coils can be avoided; if twine the resistance wire of different diameters on the coil post, see the accessible and adjust the distance between two metal hoop sheets 4, when two metal hoop sheets 4 distance increases, the screw thread distance between in the screw thread circle 21 increases, can twine the great resistance wire of diameter, when two metal hoop sheets 4 distance reduce, the screw thread distance between in the screw thread circle 21 reduces, can twine the less resistance wire of diameter, can twine the resistance wire of different diameters according to the requirement that uses the slide rheostat.

As a specific embodiment of the present invention, grooves 22 are symmetrically formed on the outer ring of the resistance coil column 2, and when the resistance coil is wound around the resistance coil column 2, the resistance coil is tightly attached to the inner wall of the groove 22; the resistance coil is tightly wound on the groove 22, so that the contact piece 54 stably slides on the outer ring of the resistance coil column 2; when the slide rheostat is used, if the sliding block 52 rotates around the guide post 3, the sliding block 52 twists the guide post 3 because the guide post 3 is hollowed out, so that the guide post 3 is twisted and damaged, and the slide rheostat cannot be normally used; when the contact piece 54 slides in the groove 22 in the resistance coil column 2, the groove 22 can restrict the contact piece 54 from swinging back and forth, so that the sliding block 52 is limited to rotate around the guide column 3, and meanwhile, the resistance coil is tightly wound on the inner wall of the groove 22, so that the resistance coil can be further fastened, and the resistance coils are more closely attached together.

As a specific embodiment of the present invention, the spring plate 55 is connected to the abutting piece 54 through a third bolt 551, one end of the third bolt 551 abuts against the abutting piece 54, and the other end of the third bolt 551 penetrates through the spring plate 55 and is in threaded connection with the spring plate 55; the extrusion force of the abutting contact piece 54 to the resistance coil is adjusted by rotating the second bolt 53; when the sliding rheostat is used, after the abutting sheet 54 and the elastic sheet 55 are used for a long time, the original elasticity of the abutting sheet 54 and the elastic sheet 55 is reduced, and the abutting sheet 54 can be effectively clamped on the surface of a resistance coil, so that the sliding rheostat cannot be normally used; through rotatory No. three bolt 551 increase conflict piece 54 and resistance coil between the attached effect, when adjusting No. three bolt 551, the distance between conflict piece 54 and shell fragment 55 crescent, the distance between conflict piece 54 and the resistance coil dwindles gradually simultaneously, and in the last conflict piece 54 lower extreme was extruded recess 22, conflict piece 54 can effectively contact with resistance coil once more.

As a specific embodiment of the present invention, a strip-shaped protrusion 541 attached to the groove 22 is disposed at the lower end of the contact piece 54; the strip-shaped bulge 541 realizes the accurate adjustment between the contact piece 54 and the resistance coil; when the sliding rheostat is used, in order to increase the contact effect between the contact piece 54 and the resistance coil and to enable the measurement result of the sliding rheostat to be more accurate, the strip-shaped protrusion 541 is arranged on the lower end surface of the contact piece 54, and when the protrusion 541 is in contact with the surface of the resistance coil, the protrusion 541 can be attached to the surface of the resistance coil, so that the problem that the contact between the contact piece 54 and the resistance coil is poor is solved.

As an embodiment of the present invention, a plurality of oval balls 542 are disposed in the middle of the protrusion 541, and the balls 542 are embedded in the protrusion 541; the friction force between the abutting piece 54 and the resistance coil is reduced by the rolling balls 542; when the resistance coil is used, when the contact piece 54 slides on the surface of the resistance coil, if the contact piece 54 is adjusted, the extrusion force between the contact piece 54 and the resistance coil is too large, so that the sliding block 52 is difficult to slide on the guide post 3, and the abrasion on the surface of the resistance coil is accelerated; ball 542 is settled to protruding 541 middle part, reduces the frictional force between contact 54 and the resistance coil, reduces the wearing and tearing between contact 54 and the resistance coil, and simultaneously, contact 54 makes a round trip to slide more smoothly on the resistance coil surface to make sliding block 52 change in the slide of guide pillar 3 surface.

When the rheostat is used, after the rheostat is used for a long time, the surface of the guide post 3 is abraded, and when the sliding rheostat is used, the sliding block 52 automatically slides, so that the measuring result of the rheostat is inaccurate; the first bolt 34 can be rotated, the first bolt 34 is rotated, the expansion block 31 is pulled through the first rope, then the expansion block 31 is gradually close to the sliding block 52, then the expansion block 31 extrudes and expands the guide post 3 in the sliding block 52, the guide post 3 and the sliding block 52 are extruded with each other, the sliding block 52 is prevented from sliding on the guide surface, and the measuring result of the slide rheostat is more accurate; by rotating the fastening bolt 51, then the first gear 511 of the fastening bolt 51 rotates and drives the second gear 531 on the second bolt 53 to rotate, then the second gear 531 rotates to spirally lift the extrusion sheet 532 and extrude the outer ring of the guide pillar 3, and the extrusion force of the extrusion sheet 532 is uniformly distributed on the surface of the guide pillar 3 through the symmetrically arranged extrusion sheets 532, so that the bending deformation of the hollow part of the guide pillar 3 due to extrusion can be avoided; after the contact piece 54 repeatedly slides on the coil back and forth for many times, the resistance coils are loosened, the resistance coils are not tightly wound, and when the sliding rheostat is used again, the measurement result is inaccurate; the surface of the outer ring of the resistance coil column 2 is sleeved with a threaded ring 21, so that the resistance coil is wound around the threaded ring 21, and the phenomenon of looseness among the resistance coils can be avoided; if resistance wires with different diameters are wound on the coil post, the distance between the two metal hoop sheets 4 can be adjusted, when the distance between the two metal hoop sheets 4 is increased, the thread distance between the inner parts of the thread ring 21 is increased, and the resistance wire with a larger diameter can be wound; when the slide rheostat is used, if the sliding block 52 rotates around the guide post 3, the sliding block 52 can twist the guide post 3 because the guide post 3 is hollowed, so that the guide post 3 is twisted and damaged, and the slide rheostat cannot be normally used; when the contact piece 54 slides in the groove 22 in the resistance coil column 2, the groove 22 can restrict the contact piece 54 from swinging back and forth, so that the sliding block 52 is limited to rotate around the guide column 3, and meanwhile, the resistance coil is wound tightly close to the inner wall of the groove 22 and can be further fastened, so that the resistance coils are more closely attached together; after the contact piece 54 and the elastic piece 55 are used for a long time, the original elasticity of the contact piece 54 and the elastic piece 55 is reduced, and the contact piece 54 can be effectively clamped on the surface of the resistance coil, so that the slide rheostat cannot be normally used; the third bolt 551 is rotated to increase the attaching effect between the contact piece 54 and the resistance coil, when the third bolt 551 is adjusted, the distance between the contact piece 54 and the elastic sheet 55 is gradually increased, meanwhile, the distance between the contact piece 54 and the resistance coil is gradually reduced, finally, the lower end of the contact piece 54 is extruded into the groove 22, and the contact piece 54 can be in effective contact with the resistance coil again; in order to increase the contact effect between the contact piece 54 and the resistance coil and to make the measurement result of the sliding rheostat more accurate, the strip-shaped protrusion 541 is arranged on the lower end surface of the contact piece 54, and when the protrusion 541 is in contact with the surface of the resistance coil, the protrusion 541 can be attached to the surface of the resistance coil, so that the problem of poor contact between the contact piece 54 and the resistance coil is avoided; when the abutting piece 54 slides on the surface of the resistance coil, if the abutting piece 54 is adjusted, the extrusion force between the abutting piece 54 and the resistance coil is too large, which causes the sliding block 52 to be difficult to slide on the guide post 3 and accelerates the abrasion of the surface of the resistance coil; ball 542 is settled to protruding 541 middle part, reduces the frictional force between contact 54 and the resistance coil, reduces the wearing and tearing between contact 54 and the resistance coil, and simultaneously, contact 54 makes a round trip to slide more smoothly on the resistance coil surface to make sliding block 52 change in the slide of guide pillar 3 surface.

The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are given by way of illustration of the principles of the present invention, and that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.