Connection terminal assembly for stator coil

The opposite end flanges 1d, 1e of a stator bobbin are provided with apertures 1a, 1b and clamping recesses 1c to firmly retain push-inserted terminal plates 3 and lead wires 4 during encapsulation by a molding resin 5. The retention of the terminal plate ends is implemented by spring flukes 3c snapping into engagement with flange apertures 1b during insertion.

BACKGROUND OF THE INVENTION 
This invention relates to a connection terminal assembly for the stator 
coil of a motor. 
FIGS. 1 and 2 show exploded and assembled perspective views of a 
conventional connection terminal assembly for the stator coil of a 
stepping motor, as disclosed in Japanese Utility Model Publication No. 
116855/81, wherein the flanges 11 and 12 on the opposite ends of a bobbin 
20 are provided with arcuate notches or recesses 13, 14 to accommodate the 
mounting of a terminal holder 30. The holder is equipped with terminal 
clips 31, 32 which are respectively connected to lead wires 6, 7 and the 
ends 21, 22 of the stator coil during assembly as shown in FIG. 2. The 
assembly is completed by the stator core cup 40 and cover 50 provided with 
meshing or interleaving teeth 41, 51. 
Such a conventional construction or arrangement suffers from the 
disadvantage that the vibration of the terminal holder 3 during the 
operation of the motor tends to loosen and even sever the connections 
between the terminal clips 31, 32 and the lead wires 6, 7 and stator coil 
ends 21, 22. Attempts have been made to solve this problem by molding or 
encapsulating the connections between the coil ends and the lead wires in 
resin, but this has resulted in short circuiting problems due to the very 
delicate and flexible nature of the thin coil ends and lead wires and 
their attendant tendency to migrate against one another during the high 
throughput rate molding process or to become exposed at the surface of the 
molding resin. 
SUMMARY OF THE INVENTION 
These drawbacks and disadvantages of the conventional stator coil assembly 
are effectively overcome in accordance with the present invention by 
fixedly securing elongate, axially oriented terminal plates between the 
bobbin flanges and overlying the stator coil during their encapsulation 
with molding resin. Such securement is implemented by providing a snap 
retention element on one end of each terminal plate which is inserted into 
and cooperates with an associated aperture in one of the bobbin flanges. 
The opposite end of each terminal plate, or the proximate portion of a 
lead wire secured thereto, is pushed into a clamping recess in the other 
bobbin flange.

DETAILED DESCRIPTION OF THE PREFERRED EMPODIMENTS 
Referring to the embodiment shown in FIGS. 3-5, a molded resin winding 
spool or bobbin 1 is provided with flanges 1d and 1e at its opposite ends. 
A thickened portion of the flange 1d has three inwardly extending 
apertures 1a, either radially oriented or parallel to each other, and 
three further, axially directed apertures 1b extending completely through 
the flange or terminating at their intersections with the apertures 1a. 
The flange 1e on the opposite end of the bobbin is formed with an 
outwardly extending sector or segment defining three spaced push-clamp 
recesses 1c oriented axially opposite the apertures 1a. The split or 
center tapped stator coil 2 wound around the bobbin has three connection 
leads or wire ends 21, 22, 23. 
The assembly further comprises three L-shaped terminal plates 3 having 
axial arms 3a, to which lead wires 4 are secured by pinch or squeeze 
clamps 3d. The radial arms 3b of the terminal plates are provided with 
outwardly bent spring flukes 3c and upstanding posts or projections 3e to 
which the respective stator coil leads 21, 22, 23 are connected by 
soldering or the like. 
During assembly the radial arms 3b of the terminal plates are push inserted 
into the flange apertures 1a until their spring flukes 3c snap into 
engagement with the apertures 1b, the lead wires 4 are simultaneously 
pushed into the clamping recesses 1c in the opposite flange, the stator 
coil leads are soldered to the terminal plate posts 3e, and a potting or 
encapsulating resin 5 is molded around the outer circumference of the 
assembly. A stator core cup and cover (not shown) would then be applied to 
complete the assembly as shown in FIGS. 1 and 2. With such a construction 
the spring flukes 3c positively retain the terminal plates in their 
installed positions due to the snap engagement between the flukes and the 
apertures 1b, and the opposite ends of the plates are similarly retained 
in their fixed positions by the push insertion of the lead wires 4 into 
the clamping recesses 1c. The installed terminal plates and lead wires are 
thus firmly held in position during the resin molding process, and the 
inadvertent short circuiting contacts between the lead wires and/or their 
exposure at the surface of the molding resin 5, as experienced with the 
conventional assembly described above, are fully avoided. 
In the modification shown in FIG. 6 the apertures 1b in the thickened 
portion of the end flange 1d for accommodating the spring flukes do not 
extend completely through the flange, but instead are in the form of blind 
bores or recesses terminating short of the outer end surface of the 
flange. In the modification shown in FIG. 7 the terminal plates are 
straight rather than L-shaped, i.e. the arms 3b are omitted, the ends of 
the plates extend through the axial apertures 1b rather than the radial 
apertures 1a, the spring flukes 3c snap engage the apertures 1a, the inner 
pinch clamps 3d also serve as connecting posts for the stator coil leads, 
and the outer pinch clamps instead of the lead wires are pushed into the 
flange recesses 1c. In the FIG. 8 embodiment the spring flukes 3c on the 
terminal plates are replaced by open apertures 3f which are snap engaged 
during insertion by saw tooth flukes 1f extending inwardly from the end 
flange 1d. 
The center tapped or split stator coil could obviously be just a single 
coil having two lead wire ends as shown in the conventional stator 
assembly.