Terminal block

A terminal block is disclosed having a leaf spring, a contact, a cam member, and a spring member. The contact is positioned adjacent to the leaf spring and has a contact seat. The contact seat has a projection extending towards the leaf spring and is positionable in a hole of a ring terminal inserted into the terminal block. The cam member is in rotatable contact with the leaf spring, has a rotational axis extending in a direction of insertion of the ring terminal, and when in contact with the leaf spring, presses the leaf spring against the contact. The spring member is located closer to the leaf spring than the contact seat and biased against the inserted ring terminal.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119(a)-(d) to Japanese Patent Application No. 2013-206345, filed on Oct. 1, 2013.

FIELD OF THE INVENTION

The present invention relates to a terminal block connecting a ring terminal terminated to a distal end of a cable.

BACKGROUND

Conventionally, a terminal block of a type in which screws are inserted into holes of ring terminals and the screws are fixed to threaded holes of contact seats is widely used. In these terminal blocks, to install the screws when they are completely detached from the contact seat, the screws need to be inserted into the holes of the ring terminals, and then screwed into the contact seats in order to fix the ring terminal. This multistep process results in a process-heavy workload required to mount the ring terminal.

Alternative designs of a terminal block of a type that can reliably fix ring terminals with fewer steps is desired. While several alternative designs have been developed to solve this long-felt need in the industry, none of these designs offers the reliability desired, while reducing the number of assembly steps.

For example, Japanese Patent Application No. 2000-306617 (“Reference 1”) discloses a relay ground terminal for a residential distribution board. A ground wire is inserted into a housing, and a locking metal element is crimped to the ground wire by rotationally operating an operation lever. The operation lever is equipped with a cam face to drive an auxiliary member to the ground wire. While this design reduces the number of assembly steps, reliability is not increased, because the ring terminal can be pulled out when the ground wire is pulled with a sufficient force.

Japanese Patent Application No. 2007-165323 (“Reference 2”) discloses an electrical terminal in that uses an operation cam to fasten a conductor, where the conductor is fastened through a pivoting action of the operation cam. The conductor is inserted into a through-hole, and the operation cam is rotationally operated to produce a camming action that fastens the conductor.

Further, Japanese Patent Application No. 2008-64266 (“Reference 3”) discloses a terminal device in which a conductor is secured by insertion into a locking hole of a locking spring. A release lever having a cam is rotationally operated to fasten the conductor through the pivoting action of the cam spaceion.

Similarly to Reference 1, References 2 and 3 also suffer from the ring terminal being pulled out accidentally when the conductor is pulled on. Further, since the insertion direction of the electric wire is different from the direction of a rotation axis of the cam, it is difficult to achieve a low profile terminal block.

Therefore, a terminal block is needed to reliably hold a conductor and to do so using a minimum number of steps.

SUMMARY

A terminal block has a leaf spring, a contact, a cam member, and a spring member. The contact is positioned adjacent to the leaf spring and has a contact seat. The contact seat has a projection extending towards the leaf spring and is positionable in a hole of a ring terminal inserted into the terminal block. The cam member is in rotatable contact with the leaf spring, has a rotational axis extending in a direction of insertion of the ring terminal, and when in contact with the leaf spring, presses the leaf spring against the contact. The spring member is located closer to the leaf spring than the contact seat and biased against the inserted ring terminal.

DETAILED DESCRIPTION OF THE EMBODIMENT(S)

In an embodiment shown inFIG. 1, a terminal block1has a front housing20coupled to a rear housing60. Heads11of thirty-six cam members10(described later) are arranged in upper and lower rows positioned in the front housing20. A cross-shaped groove111receiving a screwdriver is formed in the head11, also known as a “Phillip's head”. A terminal receiving space21receiving a ring terminal72(described later) is provided below the respective heads11in the front housing20.

In an embodiment shown inFIG. 2, the terminal block1is shown having the cam members10, the front housing20, leaf springs30, C-rings40, contacts50, and the rear housing60.

In the embodiment shown inFIG. 3, a cable assembly70includes a cable71and the ring terminal72disposed at a distal end of the cable71. A hole721is formed in an approximate center of the ring terminal72.

The terminal block1receives and fixes the ring terminal72of the cable assembly70.

In the embodiment shown inFIGS. 4(A) and 4(B), the cam member10has a unidimensionally-extending overall shape, with a rotational axis positioned along the length. The cam member10includes the head11in which a cross-shaped groove111, which has been described with reference toFIG. 1, is formed. A screwdriver (not shown) is inserted into this cross-shaped groove111to rotate the cam member10.

The cam member10further includes a rotating cam12positioned directly behind the head11. The rotating cam12presses the leaf spring30against the contact50when the cam member10is rotationally operated.

A projection13is positioned upright directly behind the rotating cam12on the cam member10. The projection13functions to abut on a stopper25(seeFIGS. 10 and 11) of the front housing20when this cam member12is rotated, and block the cam member12from rotating any further.

A circumferential groove14circling around the cam member10is formed in a rearmost end of the cam member10, opposite the head11. The structure of the circumferential groove14is such that the C-ring40is fitted in the circumferential groove14to prevent the cam member10from slipping out from the front housing20.

The front housing20is provided with the terminal receiving spaces21which have been described with reference toFIG. 1. The contact50, inserted through a rear face of the front housing20, is positioned in the terminal receiving space21such that when the ring terminal72(seeFIG. 3) is inserted from the terminal receiving space21, the contact50receives the ring terminal72.

A cam member receiving space22is formed above each terminal receiving space21of the front housing20. The cam member10is inserted into the front housing20from the cam member receiving space22, and positioned in the front housing20with the head11of the cam member10exposed as shown inFIG. 1.

A plurality of grooves23are provided in a rear end of the housing20for coupling with the rear housing60(seeFIGS. 1 and 2), and a coupling projection24is formed in the groove23for being positioned in a coupling hole64of the rear housing60(seeFIG. 9).

In the embodiment shown inFIGS. 6(A) and 6(B), the leaf spring30extends as a cantilever from a base31, is folded back towards the spring base31, and extending approximately half of the length back towards the base31. The spring base31will be press-fitted in the front housing20.

The leaf spring30is positioned adjacent to the contact50inside the front housing20, between the contact50and the cam member10.

The leaf spring30has a extending member32cut-and-bent toward the contact50. The function of the extending member32is described below. A bead33projecting from the leaf spring30toward the cam member10is formed on the folded back portion of the leaf spring30that extends toward the base31. The function of the bead33is also described below.

In an embodiment shown inFIGS. 2,7, and17, the C-ring40is positioned in the rearmost circumferential groove14of the cam member10, when the cam member10is inserted in the cam member receiving space22of the front housing20. The C-ring40functions to prevent the cam member10from slipping out of the front housing20.

In the embodiment shown inFIGS. 8(A) and 8(B), the contact50is provided with a first contact52connected to a contact base51, and a second contact53positioned adjacent to the contact base51. The contact base51is press-fitted into the front housing20.

The first contact52is a positioned in the front housing20and contacts the ring terminal72of the cable assembly70shown inFIG. 3. The second contact53is a positioned in both the front housing20and the rear housing60in a bridging manner and contacts a contact of another device electrically conducted with the cable with the ring terminal70via the terminal block1.

As shown inFIGS. 8(A) and 8(B), the first contact52has a contact seat521and a spring member522. An annular projection521ais positioned on the contact seat521and extends toward the leaf spring30when assembled to the front housing20. When the ring terminal72is inserted, the projection521aengages the hole721to firmly secure the cable assembly70.

Further, the contact seat521has a contact hole521bpositioned in an approximate center of the projection521a. The contact hole521bcatches the extending member32formed in the leaf spring30.

A contact stopper521c composed of a cut-and-bent piece positioned adjacent to the projection521aof the contact seat521. The contact stopper521cabuts a distal end of an inserted ring terminal72, thereby restricting the position in an insertion direction of the ring terminal72such that the ring terminal72unable to be inserted any further.

The spring member522is positioned closer to the leaf spring30than the contact seat521(seeFIG. 13), and functions to bias the inserted ring terminal72to the contact seat521.

When the ring terminal72is inserted between the contact seat521and the spring member522, the spring member522presses the ring terminal72against the contact seat521, while the ring terminal72rides over the projection521auntil the distal end of the ring terminal72abuts against the contact stopper521c. At this time, the projection521ais positioned in the hole721of the ring terminal72and secured thereto. When the projection521ais inserted into the hole721, a clicking sound and vibration is produced, alerting a user that the ring terminal72has been fully inserted and is retained in the terminal block1.

The spring member522is bifurcated, having a folk-like shape, and extends along both sides of the projection521a, such that the projection521ais positioned between the spring member552. The bifurcated structure of the spring member522ensures that both sides of the hole721of the ring terminal72are pressed against the contact seat521. In addition, the folk-like shape of the spring member522causes the contact hole521bto be assessable to the extending member32of the leaf spring30. The extending member32is positioned in the contact hole521b.

In the embodiment shown inFIG. 9, the rear housing60includes openings and mating contact insertion spaces62. The openings61are arranged in upper and lower two rows formed in a front of the rear housing60. The mating contact insertion spaces62are formed in a back face of the rear housing, each of which communicates with one of the openings61, such that the opening61and the mating contact insertion space62form a through-hole. A portion of the second contact53is positioned in the opening61. A mating contact of a device (not shown) connected electrically to the cable71with the ring terminal70, via the terminal block1, is inserted into the mating contact insertion space62. This inserted mating contact is electrically connected to the second contact53of the contact50of the terminal block1.

A plurality of locking tabs63formed on the rear housing60, and are positioned in a row along an upper and a lower edge of the rear housing60. Each locking tab63has a groove projection receiving hole64. The front housing20has a plurality of complementary locking tab receiving grooves23, each locking tab receiving groove23having a groove projection24. When the locking tabs63are inserted into the locking tab receiving grooves23, and the groove projection24(seeFIG. 5) is inserted into the groove projection receiving hole64to couple the front housing20and the rear housing60are together.

In the embodiment shown inFIG. 10, the terminal receiving spaces21are arranged in upper and lower rows in the front housing20, and the cam member receiving spaces22are each arranged above the terminal receiving space21. The stopper25projects into the cam member receiving space22. The stopper25functions to restrict the degree of the cam member10rotation such that rotational degrees of freedom are limited are restricted to a predetermined amount. Each stopper25has a first abutting face251and a second abutting face252.

When the cam member10is rotated in a direction of releasing the leaf spring30from the state of being pressed against the contact50, the first abutting face251abuts against the projection13of the cam member10, thereby stopping the cam member10from rotating. The position of the cam member10as shown inFIG. 12is defined as a “released position”.

When the cam member10is rotated in a direction to press the leaf spring30against the contact50, the second abutting face252contacts the projection13of the cam member10, stopping the rotation of the cam member10. This position of the cam member10is defined as a “pressed position”.

In the embodiment shown inFIG. 12, the projection521a, the contact stopper521c, and the spring member522are positioned in the terminal receiving space21, where the cam member10is in the released position.

In the embodiment shown inFIG. 13, the leaf spring30is positioned away from the contact50, with the contact50being ready to receive the ring terminal72.

In the embodiment shown inFIG. 14, the ring terminal72is partially inserted, and the spring member522of the contact50has been displaced by the ring terminal72.

In the embodiment shown inFIG. 15, the distal end of the inserted ring terminal72has contacted the contact stopper521c, and the projection521aof the contact seat521of the contact50has been inserted into the hole721of the ring terminal72. Since the projection521aof the contact seat521of the contact50is inserted into the hole721of the ring terminal72, the ring terminal72is prevented from disengaging and ejecting from the terminal block1if an outward force is placed on the cable71.

In the embodiments shown inFIGS. 16 and 17, the cam member10has been rotated from the released position shown inFIG. 12to the pressed position. In the pressed position, the projection13of the cam member10has contacted the second abutting face252of the stopper25. As the cam member10is rotated to the pressed position, the rotating cam12of the cam member10rides over the bead33(also seeFIG. 6(A)) formed on the leaf spring30. The bead33increases the force necessary to rotate the cam member10from the pressed position to the released position, thus preventing the cam member10in the pressed position from rotating accidentally to the released position.

Additionally, since the leaf spring30is pressed against the contact50by the rotating cam12while in the pressed position, and the extending member32of the leaf spring30is positioned into the contact hole521bof the contact seat521the ring terminal72is further prevented from disengaging and ejecting from the terminal block1if an outward force is placed on the cable71.

To remove the ring terminal72from the terminal block1, the cam member10is rotated from the pressed position to the released position. The rotation of the cam member contact50releases the pressure of the leaf spring30, thus displacing the extending member32of the leaf spring30is from the contact hole521b. In this manner, the cam member10is rotated to the released position, and the ring terminal72can be pulled out of the terminal block1by pulling the cable assembly70.