Starter having an elastic seal member shaped to taper in a direction perpendicular to the longitudinal axis of the motor

A starter comprising: a shift lever for engaging and disengaging a pinion and a ring gear of an engine; a magnetic switch for actuating the shift lever; a motor for driving the pinion; a front case having an open end to which the magnetic switch and the motor are mounted substantially in the same direction, the pinion being enclosed in the front case; a seal portion provided in the vicinity of the open end of the front case so as to seal a gap which communicates between the inside and the outside of the front case; the seal portion including a taper face and an elastic material, the taper face having an axis of taper substantially perpendicular to the longitudinal axis of the motor, the elastic material being fitted onto the taper face so as to be disposed between the magnetic switch and the motor and so as to be urged in the direction along which a width of the taper face becomes narrower.

BACKGROUND OF THE INVENTION 
The present invention generally relates to a starter to be used, for 
example, in an internal combustion engine, and particularly, to a starter 
provided with a dust cover for protecting dust-proof and water-proof 
sealing parts disposed in the starter. 
In a starter, generally, a magnetic switch is actuated to drive a shift 
lever to thereby make a pinion and a ring gear engage with each other. 
With this type of starter, the magnetic switch and a motor are mounted so 
as to close an open end formed in a front case with the axes of both the 
magnetic switch and the motor substantially parallel to each other. When 
assembled, the motor and magnetic switch close an open end of the front 
case except for a gap between the magnetic switch and the motor. A dust 
cover, which acts as a seal member, is attached to prevent dust and water 
from entering the inside of the front case through the gap. 
Generally, the starter is assembled as follows. First, a pinion, a shift 
lever and a part of the motor are mounted in the front case. Next, a dust 
cover is attached. Finally, the magnetic switch and the body of the motor 
are attached. The dust cover is typically comprised of, for example, 
synthetic resin. The dust cover is fitted and fixed in the front case (or 
an intermediate member fixed in the front case which is hereinafter merely 
referred to as "intermediate member") in parallel with the longitudinal 
axis of the motor. Examples of this type of structure am described, for 
example, in JP-B 63-1459, and JP-A 63-16168. 
In this configuration, the dust cover fits in the front case (or an 
intermediate member thereof) in parallel with the longitudinal axis of the 
motor as described in the above references. However, several problems 
arise from this configuration. 
In order to seal the starter, it is desirable to make the outer size of the 
dust cover considerably larger than the size of a hollow in the front case 
(or an intermediate member) into which the dust cover fits. The difference 
in size increases the interference between the dust cover and the hollow 
so that the dust cover can be pushed and expanded into the hollow. If the 
interference is too large, however, the dust cover must be greatly 
deformed when the dust cover is fitted, so that assembly is difficult. 
Alternatively, to ease assembly, it is desirable to make the outer size of 
the dust cover and the inner size of a hollow of the front case (or an 
intermediate member), into which the dust cover is to be fitted, agree 
with each other as well as possible. When the sizes are similar, the 
interference is small, so that the dust cover need only be marginally 
deformed when assembled. However, with less interference between the 
members, the dust cover is not expanded into the hollow to completely seal 
the staffer. Large interference between the parts is necessary to affect 
the seal between the dust cover and the case. Accordingly, the ease of 
assembly and the integrity of the seal are incompatible considerations. It 
is impossible to both easily assemble the dust cover into the front case 
and create a good seal. 
Further, in order to ease assembly, a taper is formed in a hollow of the 
front case (or intermediate member) in parallel with the longitudinal axis 
of the motor so that the width of the hollow decreases in the fitting 
direction. The taper in the hollow of the front case (or intermediate 
member) makes it easier to assemble the dust cover. However, in order to 
create a dependable seal between the dust cover and the front case, it is 
necessary to increase the interference between the member because there is 
no means to push the back of the dust cover in the direction along which 
the taper becomes narrower, i.e., in the direction parallel to the 
longitudinal axis of the motor. Therefore, because the interference must 
be increased, the net affect of the taper is that ease of assembly is not 
improved. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a staffer 
comprising an easily assembled dust cover which produces a good seal. 
In order to achieve the above object, according to one aspect of the 
present invention, the starter comprises: a shift lever for performing an 
engagement and disengagement between a pinion and a ring gear of an 
engine; a magnet switch for actuating the shift lever; a motor for driving 
the pinion; a from case having an opening end to which the magnetic switch 
and the motor are mounted substantially from the same direction, the 
pinion being enclosed in the front case; a seal portion provided in the 
vicinity of the open end of the front case so as to seal a gap which 
communicates between the inside and the outside of the front case, the 
seal portion including a taper face and an elastic material, the taper 
face having an axis which is substantially perpendicular to the 
longitudinal axis of the motor, the elastic material being fitted into the 
taper face so as to be disposed between the magnetic switch and the motor 
and receives a force in the direction along which a width of the taper 
face becomes narrower. 
In one embodiment, the taper face is formed on the front case wherein at 
least a part of a surface of the elastic material abuts against the 
magnetic switch, and wherein at least a part of a surface of the elastic 
material abuts against the motor. 
In a further embodiment, the taper face is formed so as to be narrower from 
the magnetic switch toward the motor. The elastic material receives a 
force in the direction from the magnetic switch toward the motor. 
In a further embodiment, the taper face narrows from the motor toward the 
magnetic switch. The elastic material receives a force in the direction 
from the motor toward the magnetic switch. 
In another embodiment of the starter, the elastic material has protrusions 
on its surface which contact the taper face. 
As described above, assembly of the starter is as follows: first, the 
pinion, the shift lever, and a part of a motor are mounted in the front 
case; second, the dust cover is attached; and third, the magnetic switch 
and the body of the motor are attached. 
According to the starter of the present invention, a seal portion is 
provided in the vicinity of the open end of the front case. An elastic 
material is fitted onto a taper face in the axial direction which is 
substantially perpendicular to the longitudinal axis of the motor. The 
elastic material is disposed between the magnetic switch and the motor and 
receives a force in the direction in which the taper face becomes 
narrower. In the actual manufacturing process, therefore, the elastic 
material is fitted into the taper face after the pinion, the shift lever, 
and a part of the motor have been mounted in the front case. Subsequently, 
the magnetic switch and the motor are mounted onto the open end of the 
front case with the elastic material between the magnetic switch and the 
motor. 
Thus, by mounting the magnetic switch and the motor in the final step, the 
elastic material is forced directly or indirectly in the direction along 
which the taper face becomes narrower. The elastic material is forcibly 
pushed and expanded into the deepest part of the taper face. This ensures 
a good seal between the elastic material and the taper face even if the 
interface between is not large. Thus, it is possible to easily assemble 
the elastic material with a light force because the elastic material is 
not significantly deformed until the final assembly step. 
Further, as described above, the elastic material is firmly attached to the 
taper face even though the interference between is not significant because 
the elastic material is forcibly fit into the deepest part of the taper 
face in the final assembly step. Also, the interference between the 
elastic material and the taper face may be increased so as to improve the 
seal. Alternatively, the interference may be decreased so that the elastic 
material may be assembled with a light force without significant 
deformation. Thus, both the seal and assembly characteristics are 
improved. 
Further, since the taper face is formed on the front case and at least a 
part of the surface of the elastic material which faces the magnetic 
switch abuts against the magnetic switch, and at least a part of the 
surface of the elastic material which faces the motor abuts against the 
motor, it is possible to urge the elastic material by means of the 
magnetic switch and the motor directly in the direction along which the 
taper face becomes narrower. 
In a further embodiment, the taper face becomes narrower from the magnetic 
switch toward the motor. The elastic material is urged in the direction 
from the magnetic switch toward the motor so that the elastic material 
receives a force in the direction from the magnetic switch toward the 
motor. Alternatively, the taper face becomes narrower from the motor 
toward the magnetic switch so that the elastic material receives a force 
in the direction from the motor toward the magnetic switch. Accordingly, 
it is possible to have the taper face oriented with its axis perpendicular 
to the longitudinal axis of the motor so that the elastic material 
receives a force in the direction along which the taper face becomes 
narrower. In embodiments of the invention wherein the elastic material 
comprises protrusions on its surface which come into contact with the 
taper face, it is possible to firmly hold the elastic material in the 
taper face until the motor and the magnetic switch are mounted on the 
front case. This prevents the elastic material from coming off the taper 
face due to vibrations or the like during the manufacturing process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIGS. 1-10B, embodiments of the present invention are 
described below. 
First, a first embodiment of the present invention is described with 
reference to FIGS. 1-8. 
The structure of the starter of this embodiment is shown in FIGS. 1 and 2. 
FIG. 2 is a side view, partly in section, of a starter 50. FIG. 1 is a 
view showing the present invention in which a magnetic switch 1 and a 
motor 5 are removed from the starter 50 when viewed in the direction of 
arrow C in FIG. 2. 
In FIGS. 1 and 2, the starter 50 includes a pinion 3 which is engageable 
with a ring gear 4 of the engine. A shift lever 2 engages and disengages 
the pinion 3 and the ring gear 4. The magnetic switch 1 attracts the shift 
lever 2 to actuate it. The motor 5 drives the pinion 3. The front case 6 
encloses the pinion 3. 
The magnetic switch 1 is provided with a plunger 1a which is attracted when 
the magnetic switch 1 is actuated. A torsion spring 1b is fixed with its 
one end to the magnetic switch 1. The shift lever 2 is supported at its 
pivotal point by the magnetic switch 1b. When a key switch (not shown) is 
turned on, the plunger 1a of the magnetic switch 1 is attracted in the 
direction of arrow A so that the pinion 3 is pushed by the shift lever 2 
to the ring gear 4 so that it becomes engaged with the ring gear 4. 
Simultaneously, a moving contactor in the magnetic switch 1 is pushed by 
the plunger 1a to turn on the motor 5. The rotation of motor 5 is 
transmitted to the ring gear 4 through the pinion 3 to thereby start the 
engine. 
The magnetic switch 1 and the motor 5 are mounted, from the left in FIG. 2, 
onto an open end 6A of the front case 6 positioned in the left side of 
FIG. 2. After the motor 5 and the magnetic switch 1 have been mounted to 
the open end 6A, a gap is formed between, which is sealed by a seal 
portion 20 provided in the vicinity of the open end 6A. 
The seal portion 20 and the starter configuration are described below in 
detail. 
In FIG. 1, the seal portion 20 comprises a taper face 8 formed in the front 
case 6. A dust cover 7 is fitted on the taper face 8. The axial direction 
of the taper face 8 is substantially perpendicular (substantially up/down 
direction in FIG. 2) to the longitudinal axis of the motor 5. The taper 
face 8 is gradually narrower from the magnetic switch 1 toward the motor 5 
(downward in FIG. 2). With the dust cover 7 fitted onto the taper face 8, 
the taper face 8 constitutes a part of a seal surface. 
FIGS. 3A, 3B and 3C show the detailed structure of the dust cover 7. That 
is, FIGS. 3A, 3B and 3C are front, side and top views of the dust cover 7, 
respectively. 
In FIGS. 1, 3A, 3B and 3C, the dust cover 7 comprises an elastic material 
made from, for example, synthetic resin or the like. The dust cover 7 
comprises surfaces 7a and 7b which abut against the magnetic switch 1. It 
further comprises surfaces 7c and 7d which abut against the motor 5 so 
that the dust cover receives a force in the direction along which the 
width of the taper face 8 becomes narrower (downward in the drawing). The 
dust cover 7 further comprises surfaces 7e and 7f which abut against the 
taper face 8. 
In this embodiment, the seal portion 20 completely seals the gap so that 
the inside and outside of the front case 6 communicate with each other. 
Thus, dust, water, etc. are prevented from entering the inside of the 
front case 6 where the plunger 1a, torsion spring 1b, shift lever 2, 
pinion 3, and so on are disposed. 
With reference to FIGS. 4-8, the procedure for assembling the starter 50 in 
the actual manufacturing process is described for an embodiment of the 
invention described above. 
First, FIG. 4 shows the front case 6 when viewed from the open end 6A with 
no parts attached to the front case 6. In FIG. 4, the open end 6A of the 
front case 6 comprises a substantially figure eight shape. The motor 5 is 
mounted to the front case 6 at a lower open end portion 6A.sub.1. The 
magnetic switch 1 is also mounted to the front case 6 at an upper open end 
portion 6A.sub.2. The taper face 8, to which the dust cover 7 is to be 
fitted during a later step, is formed between the upper and lower open end 
portions 6A.sub.1 and 6A.sub.2 of the front case 6. 
Thus, the pinion 3, the shift lever 2, and the parts of the motor 5 toward 
the pinion 3 are mounted in the front case 6 as shown in FIG. 5. In FIG. 
5, only the shift lever 2 is illustrated for simplification. 
Next, the dust cover 7 is fitted onto the taper face 8 from above as shown 
in FIGS. 6 and 7. FIG. 6 is a view from the open end 6A similar to FIGS. 
10 and 5. FIG. 7 is a side view of the front case 6. To ensure a good 
seal, the width of the dust cover 7 (in the left/right direction in FIG. 
6) is made a little larger than the width of the taper face 8 (left/right 
direction in FIG. 6). A strong force is required to push the dust cover 7 
completely into the deepest and narrowest portion of the taper face 8 
(downward in the drawing). In this step of assembly, it is not necessary 
to push the dust cover 7 completely into the taper face 8, rather it is 
sufficient to push the dust cover 7 lightly. 
Finally, the magnetic switch 1 and the motor 5 are mounted to the open end 
portions 6A.sub.1 and 6A.sub.2 of the front case 6, respectively. The dust 
cover 7 is placed between the magnetic switch 1 and the motor 5, as shown 
in FIG. 8. In FIG. 8, the magnetic switch 1 is fixed to the open end 
portion 6A.sub.2 by means of bolts (not shown) in the direction from the 
rear side toward the side shown in FIG. 8 (see also FIG. 7). The motor 5 
is fixed to the open end portion 6A.sub.1 by means of bolts 5a and 5b (see 
FIG. 7). When assembled, the magnetic switch 1 pushes the dust cover 7 
toward the motor 5 in the direction along which the taper face 8 becomes 
narrower (downward in the drawing). The dust cover 7 tightly contacts the 
taper face 8, the motor 5 and the magnetic switch 1. 
According to the assembly process described above, the dust cover 7 is 
pushed in the direction toward the narrower width of the taper face 8 
because the magnetic switch 1 and the motor 5 are assembled in the final 
step as shown in FIG. 8. The dust cover 7 is forcibly fitted into the 
taper face 8 and pushed and expanded to the deepest portion of the taper 
face 8. This ensures a good seal even if the interference between the dust 
cover 7 and the taper face 8 is not large. The interference may be small, 
so that the dust cover 7 may be assembled with a light force without 
deforming the dust cover 7 significantly. Thus, because the interference 
is small, the dust cover 7 may be easily assembled. 
As described above, because the dust cover 7 is not forcibly pushed into 
the deepest portion of the taper face 8 until the final stages of 
assembly, the dust cover 7 may be initially attached to the taper face 8 
with an improper fit and less deformation as shown in FIG. 6. Accordingly, 
the size of the dust cover 7 may be increased to produce a larger 
interference, to improve the seal between the dust cover 7 and the taper 
face 8. Also, the dust cover 7 is attached with a light force and 
insignificant deformation for easier assembly. 
According to this embodiment of the starter 50, the seal portion 20 is 
provided in the vicinity of the open end 6A of the front case 6. The dust 
cover 7 is fitted into the taper face 8, with the axis of the taper face 8 
substantially perpendicular to the longitudinal axis of the motor 5, so 
that the dust cover 7 contacts the magnetic switch 1 and the motor 5. The 
dust cover 7 is forced in the direction along which the taper face 8 
becomes narrower. In a final stage of assembly, the dust cover 7 is 
forcibly pushed into the deepest portion of the taper face 8 so as to be 
fully expanded. In a previous assembly step, the dust cover 7 is attached 
with a light force without deforming the dust cover 7. Therefore, the dust 
cover 7 is easily assembled and produces a good seal. 
Next, referring to FIG. 9, a second embodiment of the invention is 
described. This embodiment comprises a dust cover with a different 
structure. 
The structure of the dust cover 107 is shown in FIG. 9. FIG. 9 is a front 
view of the dust cover 107 and corresponds to the dust cover of the first 
embodiment shown in FIG. 3A. As shown in FIG. 9, the dust cover 107 of 
this embodiment is different from the dust cover of the first embodiment 
in that reverse taper protrusions 9, which prevent the dust cover 107 from 
coming off the taper face 8, are provided on surfaces 107e and 107f of the 
dust cover 107. These surfaces abut the taper face 8 formed in the front 
case 6. The structures of the other parts of the starter are substantially 
similar to those of the first embodiment. 
According to the second embodiment, the dust cover 107 is fixedly held on 
the taper face 8 until the motor 5 and the magnetic switch 1 have been 
mounted to the front case 6 (the step of FIG. 8 in the first embodiment). 
This prevents the dust cover 107 from coming off the taper face 8 due to 
the vibrations or the like after the dust cover 107 has been attached to 
the taper face 8 (the process of FIGS. 6 and 7 in the first embodiment). 
Next, referring to FIGS. 10A and 10B, a third embodiment of the present 
invention is described. This embodiment comprises a dust cover of 
different structure and a taper face which narrows in a different 
direction. Further, equivalent parts to those of the first embodiment are 
similarly referenced. 
FIG. 10A is an enlarged view showing the structure in the vicinity of a 
taper face 108. FIG. 10B is a front view of a dust cover 207. This 
embodiment differs from the first embodiment in that the taper face 108 is 
narrower in the direction from the motor to the magnetic switch (upward in 
the drawing). This taper face 8 is reversed from the direction of taper of 
the first embodiment. Surfaces 207e and 207f of the dust cover 207 of this 
embodiment correspond to the shape of the taper face 108. In this 
embodiment, the dust cover 207 is urged in the direction from the motor 5 
to the magnetic switch 1. The structures of the other parts of the starter 
are substantially the same as those of the first embodiment. Accordingly, 
it is possible to obtain the same effect with this embodiment as that of 
the first embodiment. 
In embodiments one through three, the taper face is formed directly on the 
front case. However, the present invention is not limited to this 
structure. Rather, the taper face may be formed on an intermediate member 
or the like provided between the magnetic switch and the motor. For 
example, a shift lever is supported by a lever holder fixed in the front 
case and located between the magnetic switch and the motor. A taper face 
having an axis substantially perpendicular to the longitudinal axis of the 
motor is formed on the lever holder so that the dust cover on this taper 
face is urged toward the narrower width of the taper face. This embodiment 
has the same effect as the prior embodiments. 
According to the present invention, the seal portion is provided in the 
vicinity of the open end of the front case. An elastic material is fitted 
into a taper face, which has an axis substantially perpendicular to the 
longitudinal axis of the motor. The elastic material is located between a 
magnetic switch and a motor so that it is urged toward the narrower width 
of the taper face. Accordingly, in the final assembly step, the elastic 
material is forcibly fitted onto the taper face so as to be pushed to the 
deepest portion of the taper face and expanded. Accordingly, it is 
possible to produce a good seal without significant interference between 
the elastic material and the taper face. Thus, because the interference is 
small, the elastic material is lightly forced into the taper face without 
significant deformation when the elastic material is assembled with the 
taper face. According to the present invention, a good seal is produced 
with easy assembly. 
Further, since the elastic material comprises protrusions on the surface 
which contact the taper face, the elastic material is fixedly held on the 
taper face. It is thereby prevented from coming off the taper face due to 
vibrations inherent in the manufacturing process.