JPS6028121Y2 - air trimmer capacitor - Google Patents

Description

[Detailed description of the invention] This invention relates to an air trimmer capacitor, and particularly improves the stopper mechanism that prevents the movable electrode from being inserted further when the capacitance reaches its maximum value by moving in the axial direction. Regarding air trimmer capacitors.

Cylindrical air trimmer capacitors whose capacitance can be changed with high precision have been known.

FIG. 1 is a partially sectional front view showing an air trimmer capacitor, which is the background of this invention.

The air trimmer capacitor 10 consists of a fixed part and a movable part.

First, the detailed structure of the fixing part will be explained. The fixed electrode 11 includes a fixed base portion 111 and a plurality of cylindrical fixed shells 112 that extend from the fixed base portion 111 in the axial direction and are coaxially arranged.

The fixed shell 112 is attached by being press-fitted into a ring-shaped groove 113 formed on one side of the fixed base portion 111.

Further, in the fixed base part 111 surrounded by the fixed shell 112 with the smallest diameter, a stop disk 114 is provided in order to stop the insertion position of the moving shell 123 formed on the moving electrode 12, which will be described later, at the maximum capacitance position. is fixed.

The stop disk 114 is made of a resin material such as fluororesin, and has the function of preventing short circuits caused by contact between the fixed electrode 11 and the movable electrode 12.

A hollow cylindrical insulating tube 13 is arranged so as to surround the outer periphery of the fixed shell 112.

This insulating cylinder 13 is made of an insulator with a low dielectric constant, such as ceramic or glass.

A metallized portion 131 made of gold or the like is formed on the outer periphery of one side of the insulating tube 13 .

Then, with the fixed base part 111 and one end surface of the insulating cylinder 13 in contact with each other, the solder 141 is applied to a portion of the fixed base part 111 including the outer peripheral wall surface and the metallized part 131.

As a result, the fixed base portion 111 and the insulating cylinder 13 are fixed.

Note that there is a conducting wire 151 in the part where the solder 141 is raised.
is connected.

A bushing 16 made of metal is arranged at the other end of the insulating cylinder 13.

A metallized portion 132 is provided on the outer periphery of the other side of the insulating cylinder 13.
is formed.

Then, with the other side end surface of the insulating tube 13 and the one side end surface of the bushing 16 in contact with each other, solder 142 is applied to the outer periphery of the joint portion between the two.

A female thread 161 is formed on the inner periphery of the bushing 16 .

Further, the other side of the bushing 16 is formed in a stepped shape.

Solder 143 is applied to this stepped portion.

The other conductive wire 1 is placed on the raised part of the solder 143.
52 are connected.

Next, the configuration of the movable part will be explained.

The movable electrode 12 has a movable base portion 122 fixed to one side of a shield cap 121, and a movable shell 123 fixed to the tip of the movable base portion 122.

The movable base portion 122 has a male thread 124 formed on the outer periphery of the cylindrical portion to be screwed into a female thread 161 formed on the inner periphery of the bushing 16 .

A plurality of movable shells 123 are formed in a cylindrical shape and arranged coaxially so as to protrude from one end of the movable base portion 122 in the axial direction.

The movable base portion 122 and the movable shell 123 are attached by being press-fitted into a ring-shaped groove formed on one end surface of the movable base portion 122.

Furthermore, a central shaft 125 extending in the axial direction is provided at the center of the movable base portion 122 .

This central axis 125 serves as a guide or reference axis when inserting the movable shell 123 into the fixed shell 112.

Further, the central axis 125 comes into contact with the stop disk 114 when the movable shell 123 is inserted most into the fixed shell 112, that is, when the capacitance value is maximum, and the movable electrode 12 is further inserted toward the fixed electrode 11 side. It has the function of regulating the

However, the air trimmer capacitor 1 as shown in Fig.
0 is a stop made of fluororesin or the like facing the central axis 125 in order to prevent further insertion when the movable electrode 12 is inserted into the fixed electrode 11 side and reaches the maximum capacitance value. Since the disk 114 was formed on the fixed base portion 111, there were the following problems.

In other words, since the stop disk 114 made of fluororesin or the like has elastic force, it is compressed even when the central shaft 125 comes into contact with it, and as a result, the movable electrode 12 does not stop at a fixed position and the maximum capacitance value becomes unstable. It had become.

Furthermore, if the movable electrode 12 is inserted into the fixed electrode side more than necessary, the central shaft 125 will press the fixed base part 111 with a strong force, and the metallized part 131 and the solder 141 will peel off, damaging the fixed electrode 11. There were cases.

Furthermore, since fluorine, which is the material of the stop disk 114, is a dielectric, its temperature characteristics become unstable.

Furthermore, the stop disk 114 must be inserted into the central fixed shell, which takes time to manufacture;
It was not suitable for mass production.

Therefore, this idea has a structure that has little variation in maximum capacitance, does not get damaged even when the movable electrode is inserted to a predetermined stop position, has stable temperature characteristics, and can be manufactured at low cost. It is to provide an air trimmer capacitor.

To summarize this idea, a protrusion is provided in relation to the movable base part, and a cylindrical part having a diameter smaller than the outer diameter of the thread of the movable base part and larger than the maximum outer diameter of the movable shell fixed to the movable base part. This is because a stopper member is provided that engages with the protrusion somewhere.

Specific embodiments of this invention will be described below with reference to the drawings.

Figure 2 shows an air trimmer capacitor 2 of an embodiment of this invention.
2 is a front view showing a partial cross section of 0. FIG.

The air trimmer capacitor 20 of this embodiment is different from the one shown in FIG. Stop disk 114 shown in Figure 1
Instead, it was configured as follows.

That is, the air trimmer capacitor 20 of this embodiment is
A stop member 30 is provided between one end of the insulating cylinder 13 and the other end of the bushing 16.

This stop member 30, as shown in detail in FIG.
It is constructed by integrally forming a ring part 31 and a cylindrical part 32.

The inner diameter of this ring portion 31 is selected to be larger than the maximum outer diameter of the movable shell 123 and smaller than the outer diameter of the male screw 124 formed on the outer periphery of the movable base portion 122 (i.e., the diameter of the thread of the male screw 124). .

That is, the stopper member 30 has a shape that is obtained by rotating a member having an angular cross-section once at a radius above the inner diameter selected as described above.

The outer diameter of the cylindrical portion 32 of this stopper member 30 is the same as that of the insulating tube 13.
The inner diameter of the insulating cylinder 13 is approximately the same, or
Or chosen a little smaller.

The stopper member 30 configured as described above is attached to the insulating tube 13.
When mounting between the bushing 16 and the bushing 16, the procedure is as follows.

That is, after fixing the fixed electrode 11 and the insulating cylinder 13 as shown in FIG.
2 is fitted into the opening at the other end of the insulating cylinder 13.

One end surface of the bushing 16 is brought into contact with the other surface of the ring portion 31 .

In this state, solder 142 is applied to the outer periphery of the insulating cylinder 13 and the bushing 16 in the vicinity of their joints.

As a result, the insulating cylinder 13 and the bushing 16 are fixed with the solder 142.

At this time, there is a slight gap between the other end of the insulating tube 13 and one end of the bushing 16 that are in contact with both sides of the ring section 31, and between the outer circumference of the cylindrical section 32 and the inner circumference of the insulating tube 13. Even if there is, the solder 142 can flow and fill the gap.

Then, on the outer periphery of the movable base portion 122 of the movable electrode 12, at the position where the movable shell 123 is inserted most into the fixed shell 112, that is, at the position where the capacitance is maximum,
The protruding portion 127 is shaped so as to come into contact with the surface of the ring portion 31 on the bushing 16 side.

Note that this protrusion 127 may also serve as the male screw 124.

In that case, a base 12 having an outer diameter smaller than the outer diameter of the male thread 124 is provided on the axial outer peripheral portion of the distal end of the movable base portion 122.
6 is expressed.

The stepped portion between the base portion 126 and the crest of the male thread 124 becomes a protruding portion.

Since the other configurations are the same as those in FIG. 1, the same parts are indicated by the same reference numerals and detailed explanation thereof will be omitted.

FIG. 4 is a sectional view showing the main parts of another embodiment of this invention.

In this embodiment, a ring-shaped stopper member 41 is provided between the insulating cylinder 13 and the insulating bushing 16.

Further, when the insulated electrode 12 is inserted to the maximum capacitance position, a ring-shaped protrusion 127' is formed on the outer periphery of the movable base portion 122 facing the ring portion 41.

Note that the protrusion 127' does not have to be a ring-shaped protrusion, and may be formed only on a portion of the outer periphery of the movable base portion 122.

Further, when the protruding portion 127' is formed into a ring shape, the stopper member 41 may be formed not into a ring shape but into a simple projection.

Also in this case, the stopper member 41 and the protrusion 127
The shape and dimensions are selected such that the side surface of the

FIG. 5 is a sectional view showing the main parts of still another embodiment of this invention.

In this embodiment, a protrusion 162 is formed at one end of the bushing 16 and protrudes inward from its inner diameter, and this protrusion 162 is used as a stopper member.

As described above, according to this invention, the movable electrode can be reliably stopped at a predetermined stop position, so the amount of insertion into the fixed electrode is constant, and variations in maximum capacitance are reduced.

Further, the stopper member formed on the inner wall of the insulating cylinder or the bushing is configured to come into contact with the protrusion formed on the movable base portion of the movable electrode to prevent the movable electrode from being inserted beyond the maximum capacitance value. Therefore, the strength of the contact between the stopper member and the protrusion is large, and damage to the fixed electrode can be prevented.

Furthermore, since there is no need to provide a stop disk made of a dielectric material such as Teflon in the fixed shell, unique effects such as stabilization of temperature characteristics and cost reduction are achieved.

[Brief explanation of drawings]

FIG. 1 is a partially sectional front view of an air trimmer capacitor which is the background of this invention. FIG. 2 is a partially sectional front view of an embodiment of this invention. FIG. 3 is an illustrative view of the stopper member. FIGS. 4 and 5 are enlarged sectional views of main parts of still another embodiment of this invention. In the figure, 11 is a fixed electrode, 111 is a fixed base part,
112 is a fixed shell, 12 is a movable electrode, 122 is a movable base portion, 123 is a movable shell, 124 is a male screw (second screw portion), 13 is an insulating tube, 16 is a bushing, 30 is a stopper member, 31 is a ring portion , 32 indicates a cylindrical portion.

Claims (4)

[Scope of utility model registration request] (1) A hollow cylindrical insulating tube, a disk-shaped fixed base portion fixed to one axial end of the insulating tube, and a coaxial member extending from the fixed base portion in the axial direction inside the insulating tube. a fixed electrode including a plurality of cylindrical fixed shells disposed above; a cylindrical bushing fixed to the other axial side of the insulating cylinder and having a first threaded portion formed on its inner periphery; a movable base portion having a second screw portion on its outer periphery that is screwed into the first screw portion of the bushing; and a movable base portion that extends from the movable base portion in the axial direction and is coaxially arranged to face the fixed shell. a movable electrode including a plurality of cylindrical movable shells, and the movable base part is rotated to connect the first threaded part and the second threaded part.
An air trimmer capacitor in which a capacitance value is changed by displacing the movable base portion in its axial direction by the action of a screw portion of the movable electrode and changing the axial position of the movable shell with respect to the fixed shell. A protrusion is formed on the outer periphery of the movable base portion, and the movable electrode contacts the protrusion at a position where the movable electrode is inserted toward the fixed electrode so that the capacitance value reaches a maximum value. An air trimmer capacitor characterized by being provided with a stopper member that prevents insertion. (2) The stopper member is formed in a ring shape whose inner diameter is larger than the outer diameter of the movable shell and smaller than the outer diameter of the second threaded portion, and is arranged between the insulating cylinder and the bushing. The air trimmer capacitor according to claim (1) of the registered utility model, which is mounted between the air trimmer capacitors. (3) The stopper member has a ring portion whose inner diameter is larger than the outer diameter of the movable shell and smaller than the outer diameter of the second threaded portion, and has the same inner diameter as the ring portion. and the air according to claim 1 of the utility model registration, which is integrally formed with a cylindrical portion that fits into the insulating cylinder, and is mounted between the insulating cylinder and the bushing. trimmer capacitor. (4) The movable base portion has a cylindrical base portion having an outer diameter smaller than the outer diameter of the second threaded portion, and the protruding portion has a cylindrical base portion having an outer diameter smaller than the outer diameter of the second threaded portion. The air trimmer capacitor according to any one of claims (1) to (3) of the utility model registration claim, which is a step portion between the air trimmer capacitor and the air trimmer capacitor.