Claims:We claim:
1. A starter motor assembly (100) comprises an armature (10) surrounded by a permanent magnet (12) , a commutator, a brush plate (16), a commutator-end-shield (26) and a solenoid (24), characterized in said starter motor assembly (100)
? said commutator-end-shield (26) comprises a first hole (28) and a second hole (30);
? a seal (50) inserted from the brush plate-side through said first hole (28) and extended outside the commutator-end-shield (26);
• said seal (50) has an internal passage (52) for routing a bus bar (54) connected to at least one brush of the brush plate (16) towards a commutator-end-shield(26);
? a connection plug (60) fitted into a second hole (30) on a commutator-end-shield (26) from the brush-plate side, said connection plug (60) having at least two pin holes (62a) for routing wires (68) between said solenoid (24) and a thermal switch of starter motor.

2. The starter motor assembly (100) of claim 1, wherein said seal (50) is made of at least one of a polymeric material, a flexible material, and an elastomeric material.
3. The starter motor assembly (100) of claim 1, wherein said seal (50) comprises
? at least one locking groove (55) for engaging with said brush plate (16);
? at least one first integrated O-ring (56) above said locking groove (55), said integrated O-ring (56) engages with the commutator-end-shield (26) of said starter motor;
? a cavity (57) for filling a sealant, said cavity (57) surrounding said bus-bar (54) extended from the internal passage (52); and
? at least one second integrated O-ring (58) in the internal passage (52) for engaging with bus-bar (54).
4. The starter motor assembly (100) of claim 1, wherein at least one proximal end (54a) of said bus bar (54) is connected to at least one brush provided in the brush plate (16) and distal end (54b) of said bus bar (54) is welded to the wire extending from a terminal of said solenoid (24).
5. The starter motor assembly (100) of claim 1, wherein said connection plug (60) comprises
? a tapered bottom section (65) inserted into a groove of the brush plate (16);
? an intermediate flange (66) having semi-circular profile (66a) engaging with the commutator-end-shield (26); and
? at least two tubular sections (67) having at least two pin holes (62a) extending till the tapered bottom section (65).
6. A seal (50) for connecting a solenoid terminal to a brush plate (16) of a starter motor, said seal (50) comprises
? at least one locking groove (55) for engaging with the brush plate (16) of the starter motor;
? at least one first integrated O-ring (56) above said locking groove (55), said integrated O-ring (56) engages with the commutator end shield (26) of said starter motor;
? a cavity (57) for filling a sealant, said cavity (57) surrounding said bus bar (54) extended from the internal passage (52); and
? at least one second integrated O-ring (58) in the internal passage (52) for engaging with bus-bar (54).
7. A connection plug (60) for connecting wirings (68) from a solenoid (24) to a starter motor, said connection plug (60) comprises
? a tapered bottom section (65) inserted into a groove of the brush plate (16);
? an intermediate flange (66) having semi-circular profile (66a) engaging with the commutator-end-shield (26); and
? at least two tubular sections (67) having at least two pin holes (67a) extending till the tapered bottom section (65).
, Description:Field of the invention:
[0001] The invention relates to a starter motor assembly. More specifically, it relates to for providing a water-proof connection to wirings between a relay and the brush plate of the starter motor.
Background of the invention:
[0002] Electrical connections between a starter motor and a solenoid are prone to water intrusion. Typically, the connection between a T45 terminal of a solenoid and the starter motor includes lot components such as a terminal plate, bushes, T-bus bar, etc. This increases the complexity of the assembly and also causes problems like breakage of connections, etc. Further, chances of water entry through this connection is higher.
[0003] Similarly, the connection between other terminals of the solenoid and a thermal switch of the starter motor is also not water-proof.
[0004] Starter motors used in agricultural vehicles such as tractor are more exposed to water. If the connections are not water proof, water may enter inside the starter motor and may damage the starter motor. Further, if the water enters into the engine, it may lead to severe and expensive damage.
Brief description of the invention:
[0005] The invention discloses a starter motor assembly, a seal and a connection plug. The starter motor assembly comprises an armature surrounded by a permanent magnet, a commutator, a brush plate, a commutator-end-shield and a solenoid. The commutator-end-shield comprises a first hole and a second hole. The seal is inserted from the brush plate-side through the first hole and extended outside the commutator-end-shield. The seal has an internal passage for routing a bus bar connected to one or more brushes of the brush plate towards the commutator-end-shield. The connection plug is fitted into the second hole on the commutator-end-shield from the brush-plate side. The connection plug has at least two pin holes for routing wires between the relay and a thermal switch of starter motor.
[0006] The seal comprises one or more locking grooves for engaging with the brush plate. At least one first integrated O-ring is provided integrally above the locking groove, and is used engage with the commutator-end-shield during assembly. A cavity is provided surrounding the bus-bar for filling a sealant. A second integrated O-ring is provided in the internal passage for engaging with bus-bar. A proximal end of the bus bar is connected to one or more brushes provided in the brush plate and a distal end of the brush bar is welded to the wire extending from a terminal of said solenoid.
[0007] The connection plug has a tapered bottom section inserted into a groove of the brush plate. It also has an intermediate flange having semi-circular profile, which contacts and engages with the commutator-end-shield. The connection plug has at least two pin holes for routing wires between the relay and a thermal switch of starter motor.
Brief description of the accompanying drawings:
[0008] An embodiment of the invention is described with reference to the following accompanying drawings,
[0009] Fig. 1 shows an exploded perspective view of a typical starter motor assembly, in accordance with an embodiment of the invention;
[00010] Fig. 2 shows a side view of a commutator-end-shield fitted with a seal and a connection plug, in accordance with an embodiment of the invention;
[00011] Fig. 3a, Fig. 3b and Fig. 3c show perspective and cross-sectional views of a seal used in a starter motor assembly, in accordance with an embodiment of the invention; and
[00012] Fig. 4a show perspective view of a connection plug, Fig. 4b show perspective view of mounting arrangement of the connection plug in a commutator-end shield and Fig. 4c show cross-sectional view of a connection plug, in accordance with an embodiment of the invention; and
[00013] Fig. 5 shows an exploded perspective view of a starter motor assembly having a seal and a connection plug, in accordance with an embodiment of the invention;
Detailed description of the embodiments:
[00014] Fig. 1 shows an exploded perspective view of a typical starter motor assembly. The starter motor assembly 100 comprises an armature 10 surrounded by a permanent magnet 12, a commutator, a brush plate 16, and a pinion gear 18. An overrunning clutch is provided to engage the pinion gear 18 with an engine ring gear. A drive end shield 20 is provided for covering a driving end of the starter motor. A solenoid 24 is provided above the starter motor and connected to the brush plate 16. A commutator-end-shield 26 covers a commutator end of the starter motor.
[00015] The above paragraph only gives an overview of basic components of the starter motor assembly 100 for illustrative purpose. The starter motor assembly 100 can have additional components which are not described above.
[00016] Fig. 2 shows a side view of a commutator-end-shield fitted with a seal and a connection plug, in accordance with an embodiment of the invention. The commutator-end-shield 26 comprises a first hole 28 and a second hole 30. A seal 50 and a connection plug 60 are fitted in the first hole 28 and the second hole 30 respectively. The seal 50 is inserted from the brush plate-side through the first hole 28 and extended outside the commutator-end-shield 26.
[00017] Fig. 3a, Fig. 3b and Fig. 3c show perspective and cross-sectional views of a seal used in a starter motor assembly, in accordance with an embodiment of the invention. The seal 50 has an internal passage 52 for routing a bus bar 54 connected to one or more brushes of the brush plate 16 towards the commutator-end-shield 26. The seal 50 comprises one or more locking grooves 55 for engaging with the brush plate 16. That is, the seal 50 is fitted on the brush plate 16 using the locking groove 55. At least one first integrated O-ring 56 is provided above the locking groove 55, which is used engage with the commutator-end-shield 26 of the starter motor during assembly. A cavity 57 is provided at the top, surrounding the bus-bar 54 for filling a sealant. A second integrated O-ring 58 is provided in the internal passage 52 for engaging with bus-bar 54. Proximal ends 54a of the bus bar is connected to one or more brushes provided in the brush plate 16 and a distal end 54b of the brush bar is welded to the wire extending from a terminal of the solenoid 24.
[00018] As the seal 50 is fitted on the brush plate 16 using locking groove 55, unintended rotation of the bus bar 54 and the connected wires are prevented. The seal 50 exhibits excellent sealing characteristics and provides water-tight connection arrangement to the wires extending from the terminals e.g. T45 terminal of the solenoid 24. It provides good insulation and withstands high voltage. The first O-rings 56 avoid ingress of water effectively. The second O-ring 58 embedded at the internal passage 52 provides effective sealing to the non-uniform profile of the bus bar 54 and avoids entry of water. The cavity 57 is filled with sealant such as silicone sealant to cover the gaps formed in-between bus bar 54 and the seal 50. Further, the seal 50 has good mechanicals strength and withstands vibration and shocks. The seal 50 can be made of polymeric, elastomeric or flexible material. It exhibits excellent fire retardant characteristics as well.
[00019] Fig. 4a show perspective view of a connection plug, Fig. 4b show perspective view of mounting arrangement of the connection plug in a commutator-end shield and Fig. 4c show cross-sectional view of the connection plug, in accordance with an embodiment of the invention.
[00020] The connection plug 60 is fitted into the second hole 30 on a commutator-end-shield 26 from the brush-plate side. The connection plug 60 has at least two pin holes 62a, 62b for routing wires between the solenoid 24 and a thermal switch of starter motor. The thermal switch is mounted on the brush plate 16 to prevent power supply to starter motor, when the temperature of the starter motor (especially the brush plate region) is more than a threshold.
[00021] The connection plug 60 has a tapered bottom section 65 inserted into a groove of the brush plate 16. The connection plug 60 also has an intermediate flange 66 having semi-circular profile 66a, which contacts and engages with the commutator-end-shield 26.
[00022] At least two tubular sections 67 are provided in the connection plug. The tubular sections 67 have the two tapered pin holes 62a extending till the tapered bottom section 65. Wires 68 extending from terminals of the solenoid 24 are routed to the thermal switch through the pin holes 62a.

[00023] The connection plug 60 provides excellent water sealing characteristics, as the tubular sections 67 are tapered and have a narrow diameter at the top. Wire insertion from the bottom is easy as the tubular sections 67 have larger diameter at the bottom. The semi-circular profile 66a of the intermediate flange 66 acts as an O-ring and provides good sealing. The gradient at the tapered bottom section 65 facilitates the insertion of the connection plug 60 in the groove provide at the brush plate 16. The profile between the bottom section 65 and the flange 66 acts like an anti-rotation lock to prevent unintended movement of wires 68 and the related connection. The connection plug 60 withstands high temperature of about ~200°C and exhibits excellent fire retardant characteristics. It also provides good electrical insulation properties.
[00024] Fig. 5 shows a perspective view of a starter motor assembly having a seal and a connection plug, in accordance with an embodiment of the invention. In Fig. 3, the seal 50 and the connection plug 60 are fitted in the first hole 28 and the second hole 30 of the commutator-end-shield 26 of the starter motor. As shown in fig. 3, the seal 50 provides a water-proof connection for routing the bus bar 54 connected to the brushes with one of the terminals of the solenoid 24. Similarly, the connection plug 60 provides a water-proof connection for the wires 68 from other terminals of the solenoid 24 and the thermal switch of the starter motor. The starter motor assembly of the present invention thus provides excellent water-proof characteristics. Thus, effective use of the starter motor in applications such as agricultural vehicle, etc, is possible. Failure of starter motor due to water ingress can be avoided effectively.
[00025] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.