Electrical connectors – Metallic connector or contact having movable or resilient... – Spring actuated or resilient securing part
Reexamination Certificate
2001-06-06
2003-04-15
Ta, Tho D (Department: 2833)
Electrical connectors
Metallic connector or contact having movable or resilient...
Spring actuated or resilient securing part
C439S851000
Reexamination Certificate
active
06547608
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates particularly to a connected structure of a receptacle terminal with a pin terminal consisting of a tab, a round pin, a square-section pin or another type pin. The receptacle terminal has a contact therein for catching the pin terminal. The present invention also relates to a receptacle terminal itself receiving a pin terminal for electrical connection thereof and having a structure for reliable connection of the receptacle terminal with the pin terminal.
2. Related Art
Terminals are generally used for electrical connection of various types of electric appliances and switches. There are provided receptacle terminals and pin terminals for detachably connecting electrical cables to the appliances and switches. The receptacle terminal generally has a resilient tongue piece urged against the pin terminal inserted into the receptacle terminal for electrical connection thereof.
The pin terminal generally consist of a tab, a round pin, a square-section pin, or another type pin. The square-section pin type terminals are generally used for a print circuit board. Furthermore, pin type terminals are also used in a connector, and the terminals are joined to conductors disposed on the print circuit board.
A conventional technical art related to the terminals is disclosed in Japanese Utility Model Application Laid-open No. 61-87475, Japanese Utility Model Laid-open No. H. 4-61775, or Japanese Patent Application Laid-open No. H. 11-233181. Japanese Utility Model Application Laid-open No. 61-87475 describes a terminal decreased in material to achieve a reduced cost. Japanese Utility Model Application Laid-open No. H. 4-61775 describes a socket type contact for preventing a damage of a spring of the terminal. Japanese Patent Application Laid-open No. H. 11-233181 describes a terminal fitting for providing an adequate contact pressure between male and female terminal pieces and for allowing a smooth engagement of the terminal pieces.
Referring to
FIGS. 9
to
11
, a conventional terminal will be discussed hereinafter.
FIG. 9
is an illustration for showing a contact state of a receptacle terminal and a pin terminal.
FIG. 10
is a general longitudinal sectional view showing a connection structure of a receptacle terminal
1
′ and a pin terminal
2
′.
The receptacle terminal
1
′ is made of a metal material and has a contact A′ providing a contact line, a contact B′ providing a contact area, a resilient tongue piece
3
′, an accommodation chamber R′, a receptacle terminal securing member
4
′, a conductor connection member (not shown) for crimping an electrical cable, and an insulator crimping piece (not shown) for securing an isolator of an electrical cable. The accommodation chamber R′ has a rectangular shape constituted by a top plate
7
′, a bottom plate
8
′, and a pair of side walls SW′. The resilient tongue piece
3
′ has a fold
11
′ and a free end
12
′. Under the resilient tongue piece
3
′, there is provided a deflection restricting member
14
′ for the resilient tongue piece.
The fold
11
′ of the resilient tongue piece
3
′ provides a reaction force against a compressive deformation thereof. Furthermore, the free end
12
′ of the resilient tongue piece
3
′ contacts the bottom plate
8
′ of the receptacle terminal, while each of them keeps a resilient force, increasing the reaction force of the resilient tongue piece
3
′. The reaction force allows the pin terminal
2
′ to get caught between the resilient tongue piece
3
′ and the top plate
7
′ of the receptacle terminal. For any easy insertion of the pin terminal
2
′ into the receptacle terminal
1
′, the pin terminal
2
′ has a tapered tip
13
′.
FIG. 11
is a sectional view taken along line Y
2
′—Y
2
′ of FIG.
10
. The receptacle terminal
1
′ has a box-shaped section for receiving the pin terminal
2
′ to allow electrical connection thereof. The contact A of the resilient tongue piece
3
′ contacts the pin terminal
2
′ to define a contact line.
Meanwhile, the contact B′ provided in the top plate
7
′ contacts the pin terminal
2
′ to define a contact area. The pin terminal
2
′ has a generally square section having four round corners
9
′ and four straight lines
10
′ connecting the corners.
The receptacle terminal
1
′ has a first contact A′ which is a peak of the resilient tongue piece
3
′ and a second contact B′ of a flat surface, which holds a tab of the pin terminal
2
′ and makes the receptacle terminal
1
′ contact with the pin terminal
2
′. The contact state is a combination of a point contact and a flat surface contact (see FIG.
9
).
FIG. 12
is a partial enlarged sectional view showing a contact portion of the receptacle terminal
1
′ and the pin terminal
2
′, which is surrounded by an ellipse C of FIG.
10
. The view illustrates a detailed contact state in which the terminal top plate
7
′ of the receptacle terminal
1
′ has been contacting the pin terminal
2
′.
Next, a frictional resistance produced by the contact area when the pin terminal slides will be discussed. The receptacle terminal
1
′ has a number of minute pits and projections (roughness) as well as the pin terminal
2
′ as illustrated in the enlarged view of FIG.
12
. The resilient tongue piece
3
′ exerts an urging force Fa′ on the pin terminal
2
′, while the pin terminal
2
′ also receives a reaction force Fb′ form the receptacle terminal
1
′. With the urging forces, the pin terminal
2
′ slides in the receptacle terminal
1
′, so that a frictional force F′ is produced between the receptacle terminal
1
′ and the pin terminal
2
′. That is, the pin terminal
2
′ overcomes the frictional force F′ to move in the receptacle terminal
1
′.
When the force Fa′ urges the pin terminal
2
′ against the receptacle terminal
1
′, highest peaks of projections of the contact surfaces may engage with associated opposed portions of the contact surfaces. This engagement of the peaks is called as an actual contact hereinafter.
In
FIG. 12
, an actual contact occurs at contact portions T
1
and T
2
. Meanwhile, an apparent engagement of the contact surfaces appears over a range Tx.
At the actual contact portions T
1
, T
2
, the receptacle terminal
1
′ and the pin terminal
2
′ are engaged with each other by adhesion forces of the contacting bodies. This adhesion force engagement produces a friction force F′ at a shear movement of the contacting bodies.
As far as the adhesion force engagement is maintained, a reliable electrical connection is accomplished between the contact surfaces. However, minute sliding movements of the contacting bodies due to an external vibration force or the like wear away the projections of the contact surfaces. Thereby, the contact surfaces are brought to another contact state, causing an unstable electrical connection thereof.
Next, referring to
FIG. 13
, another conventional terminal
1
″ will be discussed. The receptacle terminal
1
″ is made of a metal material and has two opposed contacts A″, B″ each providing a contact line, a resilient tongue piece
3
″, an accommodation chamber R″, a pin terminal entrance IN″, a conductor connection member (not shown) for crimping an electrical cable, and an insulator crimping piece (not shown) for securing an isolator of an electrical cable. The accommodation chamber R″ has a rectangular shape constituted by a top plate
7
″, a bottom plate
8
″, and a pair of side walls SW″.
The resilient tongue piece
3
″ has a base
11
″ and a free end
12
″. Under the resilient tongue pi
Murakami Takao
Sato Naotoshi
Torii Chieko
Yamamoto Masaya
Armstrong Westerman & Hattori, LLP
León Edwin A.
Ta Tho D
Yazaki -Corporation
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