JPH04264373A - Binding screw terminal and terminal board - Google Patents

Abstract

PURPOSE: To avoid losing a screw and shifting an axis center by using this constrained screw to enable connection of a bare terminal part, a open tag, or a close tag to apparatus. CONSTITUTION: This constrained terminal comprises a tightening screw 8 to be screwed in a screw hole 6 located in a connection member 3 attached to an apparatus main body and a washer 9 fitted under a head of the screw 8. A second screw thread 16 is provided at a screw head 10, so that it is screwed in a screw hole 12 formed in a member attached to the main body, when an tightening motion is completed normally to keep retracting to the axis direction during and after untightening motion from the screw hole 6 in the fixed condition if the screw 8 is kept being received an untightening force.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to captive screw terminals for use in electrical appliances for connecting the ends of bare wires without special provisions or open or closed tags attached to these ends.

0002

BACKGROUND OF THE INVENTION Generally, electrical appliances are equipped with screw terminals for connecting electric wires. One type of terminal commonly used has a clamping screw whose threaded shank is screwed into a threaded section of a fixed connecting member. A washer is fitted between the threaded portion of the shank and the head of the screw. The screw/washer assembly is housed in a housing formed within the body of insulation. The dimensions of this housing are
The washer can be moved in translation.

The housing faces the head of the screw and communicates with the outside of the device through a hole formed in the body or a terminal cover attached to the body so that a screwdriver can be inserted therein. . The electrical wire is inserted between the threaded shank of the screw and the wall of the housing. The wire is clamped between the washer and the connecting member as a result of the translational movement of the washer caused by the threading of the screw.

[0004] In the case of such terminals, the screws are usually prevented from being lost by an abutment attached to the main body. When the screw is removed, the screw or washer abuts this abutment and is immobilized in the axial direction. However, it is clear that with this method it is not possible to connect conductors with closed tags. This is because the screw must be axially separated from the connecting member in order to insert the tag.

[0005] In order to keep the screw fixed and moving backward even after the screw is removed from the connecting member, the screw thread that is screwed into the thread attached to the main body of the instrument is attached to the head when the screw is removed. It has already been proposed to use provided tightening screws. However, this has the problem that it is necessary to simultaneously remove the shank of the screw and insert the head of the screw. These two actions are never completely compatible, which leads to thread jamming and/or
or cause premature wear of the engaging threads.

[0006] In an attempt to overcome this drawback, for example, US Pat. It has been proposed to engage a thread supported by. In this patent, the above-mentioned compatibility issue is addressed by the use of a bulkhead that can force the head of a screw to move axially into the threaded section (one thread separates due to the force applied to the other thread). Solved thanks to lateral flexibility.

[0007] However, this solution does not allow the screw to be lost and its center does not shift even after the screw is removed from the connecting member (the screw may become skewed in the gap between the two bulkheads). ) cannot be guaranteed. In addition, no lateral flexibility of the septum is obtained if the same septum supports two threaded portions on its opposite sides engaged with two respective threads of the screw.

[0008]

OBJECTS OF THE INVENTION It is a particular object of the present invention to prevent these drawbacks, such as loss of screws and misalignment of the axis after the screw has been removed from the connecting member.

[0009]

[Structure of the Invention] To this end, the present invention comprises an insulating body, an electrically conductive connecting member fixed to the body and provided with a screw thread, and a tightening screw, the actuation of which is intended to be removed. If you continue to receive the screw, the screw shank that is screwed into the screw hole and the main body will continue to move backward in a fixed state even after coming out of the screw hole in the connecting member. A terminal for an electrical conductor comprising an attached threaded member and a screw having an engaging threaded head, the threaded member being a bulkhead attached to the body, the bulkhead comprising: A substantially cylindrical hole extending perpendicular to the axis of a screw hole and provided with a thread into which the head of the screw can be screwed, coaxially with the axis, and when the head of the screw is screwed into the hole. Accordingly, a captive screw terminal is proposed, characterized in that it has sufficient flexibility to allow the hole to be moved axially over the necessary travel accordingly.

Thanks to this configuration, after removing the screw from the threaded hole without fear of clogging or thread damage, the screw will
While continuing to undergo a disengagement motion, the connecting member is moved away from the connecting member until the clearance between the screw and the threaded hole is sufficient to allow insertion and removal of one or more closure tags. Since the screw continues to be held coaxially with the screw hole, the screw can be screwed in again without worrying about rearranging the screw.

[0011] Naturally, the threads in the through holes can be formed during manufacture of the body. However, it is preferable that the inside of the hole is initially smooth and self-tapping by the screw when it is first removed. The invention also relates to a terminal board comprising at least one terminal as described above attached to a terminal cover by means of threads provided on the screw head.

The invention will now be described by way of non-limiting examples and with reference to the accompanying drawings, in which: FIG.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The terminals shown in the figures are mounted on an appliance housing. Of this housing, only parts 1 and 2 that are relevant to the understanding of the invention are shown. In conventional construction, the terminal includes a connecting member 3 fixed within the instrument housing 1,2. In the inner part 4 of this connecting element there are contact pads 5 for connecting another electrically conductive element forming part of the electrical circuit of the appliance.

The connecting member 3 has a threaded hole 6 facing into a cavity 7 provided in the insulation of the instrument housing. A tightening screw 8 with a tightening washer 9 fitted under the head 10 is screwed into this screw hole. The washer 9 is flat so that the conductive end of the closing tag or cable can be clamped between itself and the member 3. as needed,
The washer may be V-shaped.

The user is protected from the risk of waving the terminals by a component attached to the instrument housing, in this example a terminal cover 11 removably attached to part 2 of the instrument housing. This part (cover 11)
has a hole 12 on the axis of the screw 8 for inserting a screwdriver to tighten or loosen the screw 8. The member to be connected, for example a conductive wire or a tag 13, is inserted through a passageway 14 provided between the instrument housing and the terminal cover 11.

In this embodiment of the invention, the head 1 of the screw 8
0 has coaxially a cylindrical part with a threaded cylindrical surface 16, the cylindrical surface of the bore 12 having a thread into which the head 10 of the screw 8 can be screwed as described below. have. The axial distance between the screw hole 6 and the screw hole 12 is
It is shorter than the overall length of the screw 8, so that the head 10 of the screw 8 begins to be threaded into the screw hole 12 in the cover 11 before the screw is completely displaced from the screw hole 6.

Since the cover 11 is manufactured from a plastic material that is easy to machine, the thread provided in the hole 12 can be conveniently removed by the self-tapping action of the thread of the screw 8 when the screw is completely unscrewed for the first time. Obtainable. FIG. 1 shows a stage prior to this self-tapping, when most of the screw 8 is threaded. At this time, the head of the screw 8 and the washer 9 are located in the free space between the connecting member 3 and the terminal cover 11.

Before the screw 8 is completely removed, the head 10 is inserted into the hole 12 in the cover 11 and the self-tapping phase begins (FIG. 2). This step continues until the free end of the screw 8 is far enough away from the screw hole 6 that, for example, two closure tags 13 can be inserted (Figs. 3 and 4
). It is noted that it is impossible to completely remove the screw 8 because the washer 9 abuts the cover 11 and prevents the screw 8 from coming out (FIG. 4).

Once the tag 13 has been inserted, the screw 8 is tightened again until the tag is tightened against the connecting member 3 (FIG. 5). In this position, the head 10 of the screw 8 is no longer in the screw hole 1
2 is not engaged. To remove the tag 13, remove the screw 8 again. Then, the thread of the head 10 is screwed into the previously formed screw hole.

[0020] Adjust the thread pitch of the shank of screw 8 to head 1.
If the thread pitch is the same as that of 0, it is possible to prevent wear of the plastic material of the cover. Alternatively, the pitch of the threads on the shank may be smaller than the pitch of the threads on the head to allow faster movement when inserting or removing the closure tag. Alternatively, for reasons of size or practicality, the pitch of the threads on the shank may be greater than the pitch of the threads on the head if the cover is made of a thin flexible plastic material. If the pitches are different from each other, the two screwing operations are
Slight flexing of the covers allows them to overlap.

In any case, with the above-mentioned purpose, the part having the screw hole 12 (in this embodiment the terminal cover 11) is able to move the hole 12 in the axial direction, and the shank and head of the screw 8 The material must be thin and sufficiently flexible to compensate for the lack of compatibility in threading the two together. A shoulder 17, preferably beveled, may also be provided between the edge of the slotted head 10 and the threaded portion 16. This shoulder allows the head to
0 into the hole 12 in the cover 11 (self-centering effect).

FIG. 6 shows a terminal board according to the present invention, in which a plurality of screws 8/washers are assembled in advance to the terminal board 11 by inserting the threads provided on the screw heads 10 into the holes 12 of the cover. 9 assemblies are shown. The terminal board obtained constitutes a subassembly that can be fixed to the main body of the electrical device when manufacturing it or when assembling and wiring it at the point of use.

The cover, fitted with one or more screw/washer subassemblies, can constitute a removable component that can be added to the instrument body during manufacturing or during final assembly and wiring. Alternatively, the cover 11 may be configured as a subassembly, such as an instrument housing or an instrument cover, having the above-mentioned features and other features, such as protection against tampering.

The shank of the screw 8 has an asymmetrically shaped end 22 forming an axial projection offset from the longitudinal axis of the screw 8.
It is advantageous to have This shape may be that of a helical tooth 23 (FIG. 8) or two helical teeth 24, 2 forming a dihedron whose edge 26 is offset from the longitudinal axis of the screw 8.
5 (FIG. 9). It may also be formed by an off-center axial extension 27 (FIG. 10).

[0025] In any case, this shape 22~
27 is designed to prevent the conductor 21 from being tightened between the shank of the screw 8 and the part of the connecting member 3 facing the screw hole 6 therein. This is also
Designed to allow self-alignment of terminals during wiring. A further advantage of the invention resulting from the described configuration is that it is possible to feed the terminal with the screw locked in the unscrewed position and the washer resting against the flexible bulkhead (in this case the terminal cover 11). It is possible. this is,
Quite useful when using the terminal for the first time.

[Brief explanation of the drawing]

1 is a schematic representation of a terminal according to the invention in various stages of its use; FIG.

FIG. 2 is a schematic representation of a terminal according to the invention in various stages of its use;

FIG. 3 is a schematic representation of a terminal according to the invention in various stages of its use;

FIG. 4 is a schematic representation of a terminal according to the invention in various stages of its use;

FIG. 5 is a schematic representation of a terminal according to the invention in various stages of its use;

FIG. 6 is a perspective view of a terminal plate according to the invention.

7 is a schematic cross-sectional view of a terminal of the type shown in FIGS. 1 to 5 with a special screw having an asymmetrical end; FIG.

FIG. 8 is an axial cross-sectional view of various embodiments of screws with asymmetric ends;

FIG. 9 is an axial cross-sectional view of various embodiments of screws with asymmetric ends;

FIG. 10 shows axial cross-sections of various embodiments of screws with asymmetric ends.

[Explanation of symbols of main parts]

1, 2 Insulating body ３　　　　　　　　　　Connecting members 6 Screw hole 8 Tightening screw 9 Washer 10 Screw head 11 Cover 12 Hole 16 Screw thread 17 Shoulders

Claims (9)

[Claims] Claim 1: An insulating body (1, 2), the body (1)
, 2) and a conductive connecting member (3) provided with a screw hole (6), and a tightening screw (8). The screw shank screwed into the screw hole (6) and the main body (1 ,2
) that engages a threaded member attached to the threaded member (16
) a screw (8) having a head (10) provided with a body (1,
2), which extends perpendicularly to the axis of the screw hole (6) and extends vertically to the head (8) of the screw (8).
Coaxially with said axis is a generally cylindrical hole (12) provided with a thread into which a screw (10) can be screwed, and when the head (10) of the screw (8) is screwed into the hole. Captive screw terminal characterized in that it has sufficient flexibility to allow said hole (12) to be moved axially over the required travel accordingly. 2. Captive screw terminal according to claim 1, characterized in that it comprises a washer (9) fitted under the head (10) of the screw (8). 3. Captive screw terminal according to claim 1, characterized in that the thread of the hole (12) is obtained when the insulating body (1, 2) is manufactured. 4. The hole (12) in the member (11) attached to the insulating body (1, 2) is initially smooth and self-tapping by the screw (8) when the screw is removed for the first time. The captive screw terminal according to claim 1, characterized in that: 5. The captive screw terminal according to claim 1, wherein the member (11) attached to the insulating body (1, 2) is a removable terminal cover. 6. The shank of the screw has an asymmetrical shape (
22) at an end thereof. 7. The shape comprises a helical tooth (23) or two helical teeth (24, 25) forming a dihedron whose edge (26) is offset with respect to the longitudinal axis of the screw (8). ) The captive screw terminal according to claim 6, characterized in that it is constituted by: 8. A terminal board comprising at least one terminal according to claim 5 attached to the terminal cover (11) by a thread provided on the head (10) of the screw (8),
Terminal board, characterized in that the terminal and the cover constitute a subassembly fixed to the main body (1, 2) of the electrical appliance. 9. The cover (11) with one or more screw/washer subassemblies (8, 9) provides a removable assembly that can be added to the body (1, 2) as required. 9. The terminal board according to claim 8, characterized in that: