Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-07-14
2002-09-17
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S06800R, C310S239000, C310S238000, C290S04000F, C290S03800C
Reexamination Certificate
active
06452295
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a starter provided with a thermostat.
2. Description of the Related Art
A starter is activated by the action of switching on a start switch of a key switch, whereby an engine is ignited and started. Once the engine is ignited and started, the starter is deactivated by the action of switching off the start switch of the key switch. At that time, for reasons such as incomplete return of the key switch, etc., the start switch may not be switched off and the starter may continue to be energized even after the engine has been started, whereby the starter generates heat and is damaged by that heat.
For that reason, in conventional techniques a thermostat is built into the starter to detect the ambient temperature within the starter and terminate operation of the starter if the ambient temperature within the starter exceeds a predetermined temperature in order to prevent excessive continuous energizing of the starter.
Actual examples of such starters include starters with a thermostat built directly into one of the brushes and starters with a thermostat disposed beside one of the brushes.
FIG. 7
is a cross-section showing an example of a starter with a thermostat disposed beside one of the brushes.
In the figure, the shaft
103
of an armature
101
comprising commutator segments
102
disposed plurally around the circumference thereof and constituting a motor portion is supported by a bearing
104
so as to be able to rotate freely. The bearing
104
is inserted into and supported by a recess portion
105
a
disposed in a thin-walled rear bracket
105
which houses the armature
101
.
Brushes
106
which contact the commutator segments
102
and, together with the commutator segments
102
, constitute contacts for supplying electric current to the armature
101
are disposed in positions facing the commutator segments
102
. Lead wires
110
are connected to the brushes
106
. The brushes
106
are pressed against the commutator segments
102
with a predetermined pressure by springs
107
and are supported by brush holders
108
. The brush holders
108
are disposed at four positions equidistantly spaced around the circumference of the armature
101
and are secured to a base
109
by rivets (not shown). A female thread is disposed in the base
109
, and the base
109
and the rear bracket
105
are secured to each other by inserting a bolt from the outer end surface of the rear bracket
105
into a bore (not shown) disposed in the end of the rear bracket
105
so that the bolt engages the female thread disposed in the base
109
. In this way, the brush holders
108
are supported by the rear bracket
105
.
The brushes
106
are heated by heat generated by friction between the brushes
106
and the commutator segments
102
and by heat generated by the motor portion of the starter which is conducted to the brushes
106
. A long, slender, rod-shaped thermostat
160
for detecting increases in the temperature of the brushes due to brush heat being the heat contained in the brushes
106
and interrupting the energizing of the starter is disposed in the vicinity of the brushes
106
radially outside the brushes
106
relative to the armature
101
such that the longitudinal direction of the thermostat
160
is parallel to the axial direction of the armature
101
.
Within the thermostat
160
which comprises a hollow pipe-shaped steel terminal
165
having a closed end, one tip of a lead wire
161
which is one of two lead wires indicated by broken lines in the figure is connected to one end of a bimetallic element
162
, and a contact
163
is disposed on the other end of the bimetallic element
162
. Another contact
166
is disposed on one tip of the other lead wire
164
. The bimetallic element
162
deforms such that above a predetermined temperature the contacts
163
,
166
are open and on or below the predetermined temperature the contacts
163
,
166
are closed.
The two lead wires
161
,
164
lead from the steel terminal
165
to the outside, extending so as to be insulated from each other, and a male terminal
167
is connected to the tip of each of the lead wires
161
,
164
. A connector
168
is integrally formed by molding resin such that the two lead wires
161
,
164
are covered.
An O-ring
169
is disposed on the cylindrical outer circumferential portion
168
a
of the connector
168
. A flat plate-shaped flange
168
b
extends from the vicinity of the center of the connector
168
. The connector
168
which is integrated with the thermostat
160
is secured to the rear bracket
105
by inserting a bolt
115
into a bore
168
c
disposed in the flange
168
b
and engaging a female thread
105
a
disposed in the rear bracket
105
.
A hollow cylindrical resin holder
116
having a closed end fits over the steel terminal
165
of the thermostat
160
and is disposed on an outer circumferential portion of the steel terminal
165
.
However, in many starters with a thermostat disposed in the vicinity of the brushes, the brush heat is transferred to the thermostat by radiation through air and it takes time for the brush heat to be transferred as far as the thermostat, making the temperature increases in the thermostat slower than the temperature increases in the brushes. For that reason, in some cases the starter may possibly be damaged by heat before the operation of the starter is terminated by the action of the thermostat.
Furthermore, in starters with a thermostat built into one of the brushes, installation of the thermostat is difficult because the thermostat is embedded in the brush, and even if installation is possible the brush has to be enlarged, making the starter larger.
SUMMARY OF THE INVENTION
The present invention aims to solve the above problems and an object of the present invention is to provide a compact starter with superior heat transfer efficiency wherein the brush heat is conducted directly to the thermostat by means of a heat conducting member interposed between one of the brushes and the thermostat.
In order to achieve the above object, according to one aspect of the present invention, there is provided an engine starter comprising:
a starter motor for starting an engine, the starter motor including a brush and a brush holder; and
a control circuit for controlling the starter motor, the control circuit including a thermostat for deenergizing the starter motor when the temperature of the starter motor exceeds a predetermined temperature;
the engine starter further comprising:
a heat conducting member, having a first end thermally coupled to the brush and a second end thermally coupled to the thermostat, for conducting heat from the brush to the thermostat.
According to another aspect of the present invention, the thermostat is secured to the heat conducting member and the heat conducting member is a substantially only means for mechanically supporting the thermostat.
According to another aspect of the present invention, the heat conducting member supports the thermostat within the starter motor with a thermally insulating air gap defined therearound.
According to another aspect of the present invention, the heat conducting member is a substantially “L”-shaped metal member having first and second legs of “L”, the first leg being thermally coupled to and extending from the brush in a substantially radial direction of the starter motor, and the second leg extending in a substantially axial direction of the starter motor and substantially along the thermostat.
According to another aspect of the present invention, the second leg has a bend portion for positioning the thermostat on the second leg.
According to another aspect of the present invention, the thermostat and the second leg of the heat conducting member are wrapped together by an adhesive tape.
According to another aspect of the present invention, an electrically insulating material is interposed between the thermostat and the second leg of the heat conducting member.
According to another aspect of the present
Iwamoto Atsuya
Shiroyama Shigeru
Yagi Katsunori
Gonzalez Ramirez Julio C.
Mitsubishi Denki & Kabushiki Kaisha
Ramirez Nestor
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