, Description:FIELD OF INVENTION
The present invention relates to an engine cooling system, more particularly to a cooling system for a single cylinder diesel engine, including but not limited to use in power tillers.
BACKGROUND
Power tillers or rotary tillers are self-propelled machines of 5-18 bhp and are usually powered by single cylinder horizontal diesel engines and finds application in many agriculture operations like wet land puddling, dry land puddling, ploughing, inter-cultivation, transporting, land levelling, ridging, winnowing etc. It is the most suitable power source for wet land cultivation.
Typically, the horizontal diesel engine used for power tiller application has a thermo-siphon type cooling system. Thermo-siphon is a physical effect which refers to a method of passive heat exchange based on natural convection caused by variation in density of the fluid, which circulates a fluid without the necessity of a mechanical pump. Generally, water is used as a coolant. The heated water expands, due to which the density decreases. When it cools down, its volume decreases and hence density increases. These variations in density sets up convection currents so that circulation of water takes place. All components of water-cooling systems except the circulating pump are used in this case.
For a thermo-syphon cooling system, in order to achieve efficient circulation, the radiator top tank must be well above the engine, thus needing a high bonnet line. Cooled water enters the engine at the bottom of the cylinder, where the engine normally runs fairly cool and it heats up to maximum as it reaches the top of the cylinders. Therefore, it has a reduced cooling effect on the hottest part of the engine. It is difficult to fit an interior heater successfully without a water pump. Under conditions of very heavy load or in hot climates the water may not circulate as quickly as required. Some of the disadvantages of the thermo-syphon cooling system have been mentioned herein above.
To overcome the abovementioned problems, and for efficient usage of power tiller, there lies a need for a novel cooling system for an engine, by improving the cooling performance by virtue of better coolant flow distribution in head and cylinder block of the diesel engine, with the incorporation of a water pump, ensuring positive water circulation and removal of all the disadvantages of the thermo-siphon cooling process.
SUMMARY OF THE INVENTION
Aspects of the present disclosure are to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present disclosure is to provide a cooling system and method for controlling the temperature of a single cylinder four stroke horizontal direct injection diesel engine implementing both the thermos siphon and forced cooling method by pumping of water. The system comprises a gear driven water pump which on rotation, pumps coolant by displacement method due to the void created, and circulates water to the cylinder, cylinder head and finally through the hose pipe to the radiator. The fan assembly mounted on the radiator driven by belt from pulley cools the engine coolant by induction.
An object of the present invention is a forced cooling system using a pump, along with a provision for thermo-siphon cooling for single cylinder horizontal engine meant for Power tiller applications.
An object of the present invention is ensuring coolant flow through the engines coolant jacket.
An object of the present invention is an integral pump casing in the crankcase itself.
An object of the invention is the radiator being mounted at the top of the crankcase.
An object of the invention is the fan assembly connected to the radiator driven is by a belt.
Yet another object of the present invention is the coolant sump, from where the coolant is sucked, on rotation of the gears in the gear driven pump.
Yet another object of the present invention is to provide better cooling efficiency implies improved engine performance.
Yet another object of the present invention is reduction water changing frequency.
Yet another object of the present invention is a coolant pump discharge flow of 40-42 L/min.
Yet another object of the present invention is a weep hole for early indication of any water pump seal leak and avoidance of water mixing with engine oil in the event of a failure.
In one aspect of the present invention, cooling system for controlling the temperature of a single cylinder horizontal engine for power tiller is disclosed. The cooling system comprising a radiator mounted atop the engine crankcase by a plurality of bolts; a coolant sump; a coolant sump plate operatively engaged atop the engine crankcase; a gear driven pump adapted to circulate coolant from the coolant sump through the engine cylinder head and the radiator, wherein a coolant hose operatively connects the cylinder head to the radiator; a fan assembly mounted on the radiator, thereby cooling the coolant before entering the sump; and a thermosiphon cooling system operatively engaged to the engine crankcase.
Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The above and other aspects, features and advantages of the embodiments of the present disclosure will be more apparent in the following description taken in conjunction with the accompanying drawings, in which:
Figure 1 illustrates the perspective view of the cooling system arrangement of the engine with the Integral Volute and the water pump installation.
Figure 2 illustrates internal layout of the cooling system arrangement of the engine with the Integral Volute and the water pump installation.
Figure 3 illustrates the water pump assembly and the pump casing arrangement.
Figure 4 illustrates the gasket hole regions in reference to which the Computational Fluid Dynamics analysis of the steady state flow of the incompressible coolant flow has been done.
Figures 5(a)-(h) illustrate the Computational Fluid Dynamics analysis at the water jacket region.
Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.
DETAILED DESCRIPTION
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.
The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustration purpose only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents.
It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more of such surfaces.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments belong. Further, the meaning of terms or words used in the specification and the claims should not be limited to the literal or commonly employed sense, but should be construed in accordance with the spirit of the disclosure to most properly describe the present disclosure.
The terminology used herein is for the purpose of describing particular various embodiments only and is not intended to be limiting of various embodiments. As used herein, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising" used herein specify the presence of stated features, integers, steps, operations, members, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, members, components, and/or groups thereof. Also, Expressions such as "at least one of," when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.
The present disclosure will now be described more fully with reference to the accompanying drawings, in which various embodiments of the present disclosure are shown. The present disclosure may, however, be embodied in many different forms and should not be construed as being limited to the various embodiments set forth herein, rather, these various embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the present disclosure. Furthermore, a detailed description of other parts will not be provided not to make the present disclosure unclear. Like reference numerals in the drawings refer to like elements throughout.
The technical underpinnings of the present invention are well established. The usage of water for an engine cooling system, along with the working mechanism of a single cylinder horizontal direct injection diesel engine is well established.
The present invention lies in providing an engine cooling system for a single cylinder horizontal direct injection diesel engine.
In the present invention, a cooling system to control the temperature of an engine has been disclosed. In particular, a cooling system and method for a single cylinder four stroke horizontal direct injection diesel engine implementing forced water cooling driven by a gear pump, also having provision for thermosiphon cooling has been disclosed. The cooling system of the engine comprises of a gear driven pump, said pump circulating water through the engines coolant jacket; a radiator fitted at the top of the crankcase with a plurality of bolts, said radiator comprising a fan assembly driven by a belt, thereby cooling the coolant before entering the sump; and an integral lower radiator tank.
In one implementation, one such engine cooling system and method for cooling a single cylinder horizontal direct injection diesel engine has been provided for. The engine cooling system controls the temperature of the engine both by thermosiphon and forced cooling method, where the water is pumped by the gear driven water pump. The cooling system comprises of a gear driven water pump; radiator; fan assembly, said fan assembly driven by belt and a coolant sump.
Figure 1 illustrates the perspective view of cooling system arrangement of the engine with the integral volute and the water pump installation. As seen in the figure, the engine-cooling system assembly comprises of a crankcase (1), a gear driven water pump (2), a cylinder head (4), coolant hose (5), a box type radiator (7) and a fan assembly (8).
The gear driven water pump (2), as illustrated in figure 2, comprises of an impeller (10) which is firmly fixed over the integrated shaft (11) supported by bearings. The water pump (2) delivers coolant to the coolant jacket. Helical gear (12) is fixed on the impeller shaft (11) which gets the drive from the crankshaft. Pump casing (9) is an integrated unique feature made in the crankcase (1) itself. The volute casing profile is designed and machined on the engine crankcase to deliver the required flow of coolant which ensure Engine cooling system. Coolant sump (13) is an integrated unique feature on crankcase (1), which acts as sump and a coolant sump plate (3) operatively engaged on top of the engine crankcase (1) is for stagnation of coolant.
The gear driven water pump (2) uses the meshing of gears to pump fluid by displacement. On rotation, the gears get separated on the intake side of the pump, thereby creating a void and suction which is filled by the fluid (here water). The water is carried by the gears to the discharge side of the pump, where the meshing of the gears displaces the fluid.
Coolant hose pipe (5) connects the cylinder head (4) to the radiator (7). It is made of synthetic materials, including but not limited to rubber.
Radiator (7) is mounted over the crankcase (1) through bolts. Radiator is designed to have fins to provide sufficient surface area for heat transfer. Fins of the radiator are made of metal, including but not limiting to copper and tubes are made of Brass (solder coated). Radiator (7) is provided with a cap having an opening pressure of 0.9 Kg/sq.cm.
Coolant from sump (13) is sucked and forced into the annular gap between liner and crankcase (1). This coolant flows to the cylinder head (4) after cooling the liner. After cooling the valves, coolant flows to the radiator (7) through coolant hose (5) and reaches the sump (13). Heat carried by the coolant is cooled by the fan assembly (8) which is mounted on the radiator (7). The flow of the coolant is shown by the arrow, as illustrated in figure 1.
The fan assembly (8) mounted on radiator (7) driven by a belt from pulley connected to the engine's crankshaft.
Significantly, the cooling system arrangement of the engine of a power tiller can be used in both Thermosiphon cooling and forced cooling with no additional machining. However, the primary mode of cooling is accomplished by the forced cooling configuration. Only when the forced cooling configuration is out of order, the Thermosiphon cooling configuration operates to cool the engine. The Thermosiphon cooling configuration remains inactive or non-operational during forced cooling configuration.
A weep hole provision is provided for early indication of any water pump seal leak and avoidance of water mixing with engine oil in the event of a failure.
According to an example of the present invention, certain values of certain parameters have been used to get results as shown in tabular format here below.
For calculation of cooling area, given a certain mass flow rate, the number of tubes required in the radiator (7) can be estimated using the following relationship:

Considering the minimum area available for flow to estimate the maximum pressure drop on the water side:
Cylinder head 4 water outlet area (20mm hose) A=p/4 x d2 0.000254469 m2
Velocity v=m/ P x A 1.068715953 m/s
Pressure Drop (Cylinder head 7) (? x V2)/2 6.033998466 mbar

Estimating the Pressure drop across the radiator:

Radiator 7 Dimensions
L 11.8 mm
B 2.4 mm
Area per tube 0.00002832 m2
No of Tubes 117
Total Radiator flow area 0.00331344

Velocity v=m/ P x A 0.082076357 m/s
Pressure Drop (Radiator) (? x V2)/2 0.03558908 mbar

The Water pump (2) selected for the engine:
Parameter Value Unit
Pump speed 3500 Rpm
Back pressure (Max) 100 Mbar
Discharge 25 litre/min

The main aspect of the invention is to provide an efficient and optimum cooling system for an engine, detailed analysis of which is carried out using commercially available Computational Fluid Dynamics (CFD) code. The detailed CFD analysis for estimating the flow velocities at different critical locations to predict any stagnation causing boiling and necessary changes in the design are documented below along with the corresponding CFD diagrams being illustrated in the drawing section as seen in figures 5(a)-(h). Based on the CFD results, it is observed that the velocity distribution and heat transfer coefficients around the critical regions of the cooling jacket [Block (1) and Cylinder head (4)] are within acceptable limits and validated during engine testing and validation trials.
CFD analysis has been carried out with the actual parameters of the base engine for steady state incompressible coolant jacket analysis and the parameters used for different iterations has been given below in tabular format.
The following tables showing CFD analysis for baseline vs iteration 1 and iteration 2: boundary condition and domain (water jacket region under consideration). The reference gasket holes 1,2 and 3 are illustrated in figure 4.

The pressure drop across the system is 0.149 bar at 40 litres per minute.

The pressure drop across the system is 0.138 bar at 40 litres per minute.

Figures 5(a) and (b) illustrate the CFD analysis of the overall assembly for all the iterations, wherein the heat transfer coefficient is within the permissible limits. In the figures the colours are value indexed at the bottom.
Similarly, figures 5 (c) and (d) illustrate the CFD analysis of the block for all the iterations, wherein the heat transfer coefficient is within the permissible limits. In the figures the colours are value indexed at the bottom.
Similarly, figures 5(e) and (f) illustrate the CFD analysis of the head for all the iterations, wherein the heat transfer coefficient is within the permissible limits. In the figures the colours are value indexed at the bottom.
Figures 5(g) and (h) illustrate the velocity of the streamline flow of the coolant through the assembly for all the iterations.
Some of the important advantages of the present invention, considered to be noteworthy are mentioned below:
1. The engine has a water pump to ensure the flow of coolant through the engines coolant jacket.
2. Better cooling efficiency implies improved engine performance.
3. Improves durability of the engine.
4. Water changing frequency reduced.
5. The power tiller can be used in both Thermo siphon as well as forced cooling configuration with no additional machining required.
6. The power tiller has an integral volute in crank case (Engine block) for Water pump.
7. The water pump is driven within the engine gear train using Helical gear.
8. A weep hole provision is provided for early indication of any water pump seal leak and avoidance of water mixing with engine oil in the event of a failure.
Although an efficient method of cooling an engine, thereby increasing the engine performance and durability has been described in language specific to the structural features, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific features or devices described. Rather, the specific features are disclosed as examples of implementations of an engine cooling system, implementing both thermosiphon and forced cooling method.
Claims:1. A forced cooling system for controlling the temperature of a single cylinder horizontal engine for power tiller, said cooling system comprising:
a radiator (7) mounted atop the engine crankcase (1) by a plurality of bolts;
a coolant sump (13);
a coolant sump plate (3) operatively engaged atop the engine crankcase (1);
a gear driven pump (2) adapted to circulate coolant from the coolant sump (13) through the engine cylinder head (4) and the radiator (7), wherein a coolant hose (5) operatively connects the cylinder head (4) to the radiator (7);
a fan assembly (8) mounted on the radiator (7), thereby cooling the coolant before entering the sump (13); and
a thermosiphon cooling system operatively engaged to the engine crankcase (1).
2. The cooling system as claimed in 1, wherein the engine is a single cylinder four stroke horizontal direct injection diesel one.
3. The cooling system as claimed in claim 1, wherein the radiator (7) is provided with a cap having an opening pressure of 0.9 kg/sq.cm.
4. The cooling system as claimed in claim 1, wherein the engine has coolant pump discharge flow of 40-42 L/min.
5. The cooling system as claimed in claim 1, wherein the engine is a single cylinder horizontal diesel engine for power tiller application.
6. The cooling system as claimed in claim 1, wherein the gear driven pump (2) is operatively integrated with inbuilt volute of the engine crankcase (1).
7. A method of cooling an engine, said engine being a single cylinder diesel one, comprising a radiator (7) and a gear driven water pump (2), said method comprising the steps of:
driving the gear driven pump (2) for coolant flow, wherein the said pump comprises of a helical gear (12) operatively connected to an impeller shaft (11) and engine crankcase (1).
Claims:1. A forced cooling system for controlling the temperature of a single cylinder horizontal engine for power tiller, said cooling system comprising:
a radiator (7) mounted atop the engine crankcase (1) by a plurality of bolts;
a coolant sump (13);
a coolant sump plate (3) operatively engaged atop the engine crankcase (1);
a gear driven pump (2) adapted to circulate coolant from the coolant sump (13) through the engine cylinder head (4) and the radiator (7), wherein a coolant hose (5) operatively connects the cylinder head (4) to the radiator (7);
a fan assembly (8) mounted on the radiator (7), thereby cooling the coolant before entering the sump (13); and
a thermosiphon cooling system operatively engaged to the engine crankcase (1).
2. The cooling system as claimed in 1, wherein the engine is a single cylinder four stroke horizontal direct injection diesel one.
3. The cooling system as claimed in claim 1, wherein the radiator (7) is provided with a cap having an opening pressure of 0.9 kg/sq.cm.
4. The cooling system as claimed in claim 1, wherein the engine has coolant pump discharge flow of 40-42 L/min.
5. The cooling system as claimed in claim 1, wherein the engine is a single cylinder horizontal diesel engine for power tiller application.
6. The cooling system as claimed in claim 1, wherein the gear driven pump (2) is operatively integrated with inbuilt volute of the engine crankcase (1).
7. A method of cooling an engine, said engine being a single cylinder diesel one, comprising a radiator (7) and a gear driven water pump (2), said method comprising the steps of:
driving the gear driven pump (2) for coolant flow, wherein the said pump comprises of a helical gear (12) operatively connected to an impeller shaft (11) and engine crankcase (1).
Claims:1. A forced cooling system for controlling the temperature of a single cylinder horizontal engine for power tiller, said cooling system comprising:
a radiator (7) mounted atop the engine crankcase (1) by a plurality of bolts;
a coolant sump (13);
a coolant sump plate (3) operatively engaged atop the engine crankcase (1);
a gear driven pump (2) adapted to circulate coolant from the coolant sump (13) through the engine cylinder head (4) and the radiator (7), wherein a coolant hose (5) operatively connects the cylinder head (4) to the radiator (7);
a fan assembly (8) mounted on the radiator (7), thereby cooling the coolant before entering the sump (13); and
a thermosiphon cooling system operatively engaged to the engine crankcase (1).
2. The cooling system as claimed in 1, wherein the engine is a single cylinder four stroke horizontal direct injection diesel one.
3. The cooling system as claimed in claim 1, wherein the radiator (7) is provided with a cap having an opening pressure of 0.9 kg/sq.cm.
4. The cooling system as claimed in claim 1, wherein the engine has coolant pump discharge flow of 40-42 L/min.
5. The cooling system as claimed in claim 1, wherein the engine is a single cylinder horizontal diesel engine for power tiller application.
6. The cooling system as claimed in claim 1, wherein the gear driven pump (2) is operatively integrated with inbuilt volute of the engine crankcase (1).
7. A method of cooling an engine, said engine being a single cylinder diesel one, comprising a radiator (7) and a gear driven water pump (2), said method comprising the steps of:
driving the gear driven pump (2) for coolant flow, wherein the said pump comprises of a helical gear (12) operatively connected to an impeller shaft (11) and engine crankcase (1).