Technical Field
[0001] The present subject matter described herein generally
relates to an internal combustion engine, and particularly relates to a
coolant pump operatively coupled to a crankshaft of the internal
combustion engine.
Background
[0002] Conventionally, a coolant pump mounted to one side of a
cylinder block of an internal combustion engine is driven either by a
camshaft or a crankshaft of said internal combustion engine. Thus, either
the camshaft or the crankshaft is used to directly drive the coolant pump.
Particularly, a shaft member of the coolant pump is coupled either to the
camshaft or the crankshaft so as to drive the coolant pump. However, non
uniform torque generation inside the internal combustion engine leads to
torsional vibrations being generated both at the camshaft and at the
crankshaft. Particularly, the torsional vibrations can cause excessive
wearing or damage to the shaft member of the coolant pump when the
same is directly connected either to the camshaft or to the crankshaft. As
a result, life of the coolant pump gets affected and is reduced
considerably. Moreover, cost of replacement of the coolant pump is also
high resulting in customer dissatisfaction.
[0003] There is therefore a need for a coolant pump operated by the
internal combustion engine which is structured to withstand torsional
vibrations generated within the internal combustion engine.

Summary of the Invention
[0004] The present invention has been made in view of the above
circumstances.
[0005] It is an object of the present invention to provide a coolant
pump operatively coupled to an internal combustion engine and adapted
to withstand torsional vibrations generated in the engine.
[0006] It is another object of the present invention to provide a
coupler assembly for operatively coupling said coolant pump to the
internal combustion engine.
[0007] It is yet another object of the present invention to provide a
coupler assembly which not only operatively couples the coolant pump to
the internal combustion engine but also aids in absorbing vibrations
generated within the internal combustion engine.
[0008] It is still another object of the present invention to provide a
coupler assembly which aids in prolonging life of said coolant pump.
[0009] With the above and other objects in view, the present
invention provides a coolant pump operatively coupled to a crankshaft of
an internal combustion engine. Particularly, a coupler assembly is
provided for operatively coupling said coolant pump to the crankshaft.
Power from the crankshaft is used to drive the coolant pump through the
coupler assembly. As per the present invention, the coupler assembly
comprises a coupler member and at least one receiver member. Whereas
the coupler member operatively couples a shaft member of the coolant

pump to "the crankshaft, the at least one receiver member receives said shaft member.
[0010] In a first embodiment of the present invention, the coolant
pump is operatively coupled to the crankshaft together with a magneto assembly. Particularly, in the first embodiment, the at least one receiver member adapted to receive the shaft member of the coolant pump is disposed within the coupler member. In other words, at least a portion of the receiver member overlaps with a portion of the at least one receiver member. Further, since the coupler member operatively couples said coolant pump to the crankshaft through the magneto assembly, the shaft member also rotates along with the crankshaft, thereby actuating the coolant pump. In the first embodiment, the at least one receiver member comprises a first receiver member and a second receiver member. Whereas the first receiver member is inserted into a cavity formed in a head portion of the coupler member, the second receiver member is inserted into a central slot formed in said first receiver member and is adapted to receive the shaft member of the coolant pump. Particularly, while the first receiver member is made of a flexible material, the second receiver member is made of a rigid material. Thus, in the present embodiment, while the first receiver member serves to absorb torsional vibrations, the second receiver member serves as a sacrificial member which gets worn due to continuous rotation of the shaft member. Therefore, the coupler assembly as per the present embodiment ensures

that no damage is caused to the head of the shaft member of the coolant, pump, thereby prolonging life of the coolant pump.
[0011] In a second embodiment of the present invention, the at
least one receiver member is provided with an inner cross sectional distance which is substantially greater than an outer cross sectional distance of the coupler member, so that said at least one receiver member which receives the shaft member of the coolant pump seats over the head portion of the coupler member and rotates along with the coupler member coupling the magneto assembly to the crankshaft of the internal combustion engine. Further, in the second embodiment, the at least one receiver member is made of a thermoplastic elastomeric material capable of absorbing the torsional vibrations transferred to the shaft member of the coolant pump. Rigidity of the thermoplastic elastomeric material ensures that the at least one receiver member does not crack due to impact of the torsional vibrations, thus prolonging life of the shaft member and thereby the life of the coolant pump.
[0012] Summary provided above explains the basic features of the
invention and does not limit the scope of the invention. The nature and further characteristic features of the present invention will be made clearer from the following descriptions made with reference to the accompanying drawings.

Brief Description of Drawings
[0013] The above and other features, aspects, and advantages of
the subject matter will be better understood with regard to the following
description and accompanying drawings where:
[0014] FIG.1 is a perspective view of an internal combustion engine
in accordance with the present invention.
[0015] FIG-2 is an exploded view depicting arrangement of a
coolant pump and a coupler assembly in accordance with a first
embodiment of the present invention.
[0016] FIG.3 is an exploded view depicting arrangement of the
coupler assembly in accordance with the first embodiment of the present
invention.
[0017] FIG.4 is an exploded view depicting arrangement of the
coolant pump and the coupler assembly in accordance with a second
embodiment of the present invention.
Detailed Description of the Preferred Embodiments
[0018] The present subject matter described herein relates to a
coolant pump operatively coupled to a crankshaft of the internal
combustion engine, and particularly relates to a coupler assembly used to
operatively couple said coolant pump to the crankshaft.
[0019] Exemplary embodiments detailing features of the coolant
pump and the coupler assembly, in accordance with the present invention
will be described hereunder with reference to the accompanying drawings;
Various aspects of different embodiments of the present invention will

become discernible from the following description set out hereunder. Further, it is to be noted that the present disclosure is applicable to all vehicles.
[0020] A general description of an internal combustion engine 10 in
accordance with an embodiment of the present invention is made with reference to FIG.1.
[0021] The internal combustion engine 10, hereinafter 'engine' is a
single cylinder engine including a cylinder block 11 and a cylinder head 12. The cylinder head 12 is mounted on the cylinder block 11. In the present embodiment, the cylinder head 12 is detachably attached to the cylinder block 11. A crankshaft 13 (shown in FIG.2) which is piston driven serves as an output shaft of the internal combustion engine 10 and has a driving sprocket or a pulley (not shown) fixedly mounted thereto at one end thereof. The crankshaft 13 is disposed within the crankcase 14. Reciprocating motion of a piston disposed inside the cylinder block 11 is converted into rotary motion by the crankshaft 13. The crankshaft 13 is subject to a continuous change in angular velocity as the torque imparted to the crankshaft 13 during one complete cycle of operation of the internal combustion engine 10 keeps fluctuating. In other words, torsional vibrations are generated within the internal combustion engine 10 during each cycle of operation.
[0022] As is conventional, in order to achieve uniform torque, an
inertia mass in the form of a magneto assembly 15 (shown in FIG.2) is

attached to the crankshaft 13. In the present embodiment, the magneto
assembly 15 is disposed at one end of the crankshaft 13. The magneto
assembly 15 produces electrical power while the internal combustion
engine 10 is running to power some engine systems (for example the
ignition and fuel injection systems) and vehicle systems (for example lights
and display gauges). The magneto assembly 15 includes: a rotor 15a
(shown in FIG.2), and a stator (not shown). A magneto cover 15c provided
to cover the magneto assembly 15 externally is bolted to the crankcase
14. The stator has a plurality of permanent magnets (not shown) which
generate a magnetic field. The stator is fixedly attached to the magneto
cover 15c. The rotor 15a is mounted to a starter gear (not shown) and
therefore turns with the crankshaft 13. The rotor 15a has a plurality of wire
coils wound thereon, which generate electrical current by moving in the
magnetic field generated by the stator. The rotor 15a and the starter gear
together form the flywheel of the internal combustion engine 10, which
means that their combined rotating masses help maintain the angular
momentum of the crankshaft 13 between each ignition.
[0023] Further, a coolant pump 16 is disposed over the magneto
cover 15c and is operatively rotatably coupled to the crankshaft 13 for cooling at least a portion of the internal combustion engine 10. The coolant pump 16 is used to circulate a coolant through the engine 10 in order to remove excess heat therefrom. The coolant supplied by the coolant pump 16 aids in maintaining optimum operating temperature of the internal

combustion engine 10. A thermostat 17 is also provided, which together with the coolant pump 16 and a radiator (not shown) aids in maintaining the optimum operating temperature of the engine 10. When the coolant gets heated to a threshold temperature and the internal combustion engine 10 has attained the optimum operating temperature, the thermostat 17 directs flow of the coolant to the radiator. Thereafter, the radiator after cooling the coolant directs the same to the engine 10 through an inlet 16a of the coolant pump 16. However, in a condition when the engine 10 has not attained its optimum operating temperature, the thermostat 17 bypasses the flow of the coolant directly to the coolant pump 16 through a by pass hose 16b and back to the internal combustion engine 10 and the same continues till the internal combustion engine 10 attains the optimum operating temperature.
[0024] As illustrated in FIG.2 the coolant pump 16 is operatively
coupled with the crankshaft 13. In a first embodiment of the present invention and as may be seen in FIG.2, the coolant pump 16 is operatively rotatably coupled to the crankshaft 13 through the magneto assembly 15 by means of a coupler assembly 20. The coupler assembly 20 aids in coupling the coolant pump 16 to the crankshaft 13. As a result, the coolant pump 16 gets actuated with a rotation of the crankshaft 13. Therefore, the torsional vibrations generated at the crankshaft 13 get transferred to the coolant pump 16, particularly to a shaft member 16c of the coolant pump 16, and lead to damage of said shaft member 16c, and

ultimately leading to damage of the coolant pump 16 over a period of time. There is therefore a need to damp torsional vibrations getting transferred to the coolant pump 16.
[0025] The coupler assembly 20 as per the present invention not
only aids in operatively coupling the coolant pump 16 to the crankshaft 13 but also serves to absorb torsional vibrations. The coupler assembly 20 includes a coupler member 20a (shown in FIG.3) and at least one receiver member 20b (shown in FIG.3). While the coupler member 20a serves to operatively couple the coolant pump 16 to the crankshaft 13, the at least one receiver member 20b serves to receive the shaft member 16c of the coolant pump 16.
[0026] Features of the coupler assembly 20 and their functions as
per the first embodiment of the present invention are elaborated with reference to FIG.2 and FIG.3. As per an aspect of the present invention, the coupler member 20a provided is a bolt used to rotatably couple the coolant pump 16 to the crankshaft 13 through the rotor 15a. For example, in accordance with the first embodiment, the coupler member 20a provided is a large sized hexagonal bolt which rotatably couples the shaft member 16c of the coolant pump 16 to the crankshaft 13 through a hole 15aa provided in the rotor 15a of the magneto assembly 15. Further, the at least one receiver member 20b which receives the shaft member 16a is inserted in a cavity 20aa formed in a head portion 20ab of the coupler member 20a. Particularly, as per the first embodiment, the at least one

receiver member 20b comprises a first receiver member 20bc and a second receiver member 20bd. The first receiver member 20bc having a shape complimentary to that of the cavity 20aa is inserted into said cavity 20aa. Particularly, the first receiver member 20bc having an inner cross sectional distance substantially smaller than an inner cross sectional distance of the cavity 20aa is inserted therein. Further, the first receiver member 20bc includes a central slot 21, and at least two orifices 22 disposed around an outer periphery of the central slot 21. Preferably, the first receiver member 20bc is made of a flexible material such as rubber. The second receiver member 20bd having a shape complimentary to that of the central slot 21 is inserted in the central slot 21 formed in the first receiver member 20bc and is adapted to receive the shaft member 16c of the coolant pump 16. Thus, the second receiver member 20bd is also held in the head portion 20ab of the coupler member 20a. Preferably, the second receiver member 20bd is made of a rigid material such as plastic, metal or alloy.
[0027] When the coupler member 20a rotates along with the
crankshaft 13, the at least one receiver member 20b being inserted within said coupler member 20a also rotates causing the shaft member 16c of the coolant pump 16 to rotate. Particularly, the shaft member 16c rotates along with the second receiver member 20bd, causing the second receiver member 20bd to press against the at least two orifices 22. Based on a direction of rotation, the second receiver member 20bd presses

against any one of the at least two orifices 22, causing the same to flex and absorb torsional vibrations transferred to the shaft member 16c. Since, the shaft member 16c is directly inserted into the second receiver member 20bd, substantial amount of impact caused due to torsional vibrations is borne by the second receiver member 20bd causing it to wear. Over a period of time, the first receiver member 20bc also wears out. Thus, the at least one receiver member including the first receiver member 20bc and the second receiver member 20bd serve as sacrificial members. Thus, provision of the at least one receiver member 20b ensures that damage caused to the shaft member 16c due to torsional vibrations is eliminated. The at least one receiver member 20b including the first receiver member 20bc and the second receiver member 20bd can be replaced conveniently once worn out.
[0028] In a second embodiment of the present invention as
illustrated in FIG.4, the at least one receiver member 20b is provided as a single member. Preferably, the at least one receiver member 20b is made of a thermoplastic elastomeric material which exhibits properties of both a flexible material and a rigid material. The shaft member 16c is inserted in a central groove 23 formed in the at least one receiver member 20b. Further, the at least one receiver member 20b is located over the coupler member 20a coupling the rotor 15a to the crankshaft 13. Particularly, the at least one receiver member 20b having an inner cross sectional distance substantially larger than an outer cross sectional distance of the head

portion 20ab of the coupler member 20a, seats over the head portion 20ab of the coupler member 20a. For example, an outer mating periphery of the coupler member 20a and an inner mating periphery of the at least one receiver member 20b are provided with complimentary shapes to ensure seating of the at least one receiver member 20b over at least a portion of the coupler member 20a. Thus, as the coupler member 20a rotates, the at least one receiver member 20b also rotates and causes the shaft member 16c inserted therein to rotate, thereby actuating the coolant pump 16.
[0029] The at least one receiver member 20b made of thermoplastic
elastomeric material serves to absorb the torsional vibrations transferred
to the shaft member 16c. Moreover, since the thermoplastic elastomeric
material also possesses sufficient rigidity, it does not wear easily and
thereby aids in prolonging life of the shaft member 16c of the coolant
pump 16, and thereby the life of the coolant pump 16 is also prolonged.
[0030] As it is apparent from the above teaching, by providing a
coupler assembly as per the principle of the present invention and its various embodiments, for operatively coupling the coolant pump to the crankshaft, it is possible to dampen torsional vibrations transferred to a shaft member of the coolant pump and thereby prolong life of the coolant pump. Moreover, the coupler assembly is also easily replaceable at a low cost. Further, a compact arrangement of the coupler assembly with

minimal components ensures that drive system of the internal combustion engine remains compact.
[0031] While the present invention has been shown and described
with reference to the foregoing preferred embodiments, it will be apparent to those skilled in the art that changes in form, connection and detail may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

I/We Claim:
1. An Internal combustion engine (10) for a vehicle, said internal
combustion engine (10) comprising:
a crankcase (14);
a crankshaft (13) disposed in the crankcase (14);
a magneto assembly (15) including a rotor (15a), said rotor being
rotatably connected to the crankshaft (13); and
a coolant pump (16) operatively coupled to the crankshaft (13) for
cooling at least a portion of the internal combustion engine (10),
wherein the coolant pump (16) is operatively coupled to the
crankshaft (13) by means of a coupler assembly (20), said coupler
assembly (20) comprising a coupler member (20a), and at least one
receiver member (20b), and wherein said at least one receiver
member (20b) adapted to be inserted within said coupler member
(20a) and configured to receive a shaft member (16c) of the coolant
pump (16) dampens torsional vibrations transferred to said shaft
member (16c).
2. The internal combustion engine (10) as claimed in claim 1, wherein
the coupler member (2Qa) includes a head portion (20ab) adapted
to receive at least a portion of the at least one receiver member
(20b).

3." The internal combustion engine (10) as claimed in claim 1, wherein the coupler member (20a) is a bolt adapted to rotatably connect the coolant pump (16) to the crankshaft (13) through the rotor (15a).
4. The internal combustion engine (10) as claimed in claim 1, wherein the at least one receiver member (20b) includes a first receiver member (20bc) and a second receiver member (20bd).
5. The internal combustion engine (10) as claimed in claim 4, wherein the first receiver member (20bc) includes a central slot (21) and at . least two orifices (22) disposed around an outer periphery of the central slot (21).
6. The internal combustion engine (10) as claimed in 4 or claim 5, wherein the second receiver member (20bd) is adapted to be inserted into said central slot (21).
7. The internal combustion engine (10) as claimed in claim 4, wherein the first receiver member (20bc) is made of a flexible material.
8. The internal combustion engine (10) as claimed in claim 4, wherein the second receiver member (20bd) is made of a rigid material.
9. An internal combustion engine (10) for a vehicle, said internal combustion engine (10) comprising:
acrankcase (14);
a crankshaft (13) disposed in the crankcase (14);
a magneto assembly (15) including a rotor (15a), said rotor being
rotatably connected to the crankshaft (13); and

a coolant pump (16) operatively coupled to the crankshaft (13) for cooling at least a portion of the internal combustion engine (10), wherein the coolant pump (16) is operatively coupled to*the crankshaft (13) by means of a coupler assembly (20), said coupler assembly (20) comprising a coupler member (20a) and at least one receiver member (20b), and wherein said at least one receiver member (20b) having an inner cross sectional distance substantially greater than an outer cross sectional distance of a head portion (20ab) of the coupler member (20a) is adapted to seat over said head portion (20ab), and enable dampening of torsional vibrations transferred to a shaft member (16c) of the coolant pump (16), said shaft member (16c) being inserted in the at least one receiver member (20b). D.The internal combustion engine (10) as claimed in claim 9, wherein the at least one receiver member (20b) is made of a thermoplastic elastomeric material.