US20150345369A1

US20150345369A1 - Shunt tank for engine cooling systems

Info

Publication number: US20150345369A1
Application number: US14/826,248
Authority: US
Inventors: Nimalan Ramachandran; Thomas W. Alworth; Sampath Srinivasan; Ravikumar Natarajan
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2015-08-14
Filing date: 2015-08-14
Publication date: 2015-12-03
Also published as: CN205936796U

Abstract

A shunt tank for an engine cooling system is disclosed. The shunt tank includes a floor portion and four walls, structured and arranged to define a tank interior with a first volume. At least one of a first wall and a second wall is structured proximal to a lateral edge of a radiator frame and includes a gauge attachment portion. A third wall includes a compartment attachment portion. A sight gauge is attached to the gauge attachment portion. A lower compartment is attached to the compartment attachment portion. The lower compartment extends at least partially beyond the floor portion, towards the radiator frame. The lower compartment includes a fluid outlet and defines a second volume. The second volume is substantially less than the first volume. A fluid conduit fluidly connects the shunt tank to a fluid pump of the engine cooling system.

Description

TECHNICAL FIELD

The present disclosure relates generally to shunt tanks in engine cooling systems. More specifically, the present disclosure relates to a shunt tank with improved design to minimize cavitation in the coolant circuit.

BACKGROUND

Various machines, such as off highway trucks, are commonly known to employ an engine cooling system, to impart desired cooling to an engine. The engine cooling system generally includes a fluid pump, a radiator, and a coolant flowing therethrough. The fluid pump and the radiator are fluidly connected to the engine in a closed-loop manner. The fluid pump circulates the coolant through the engine and the radiator, to cool the engine. Additionally, the engine cooling system employs a tank, to allow for the expansion of the coolant, as it is heated by the engine. Various types of tanks that can accommodate the expansion of coolant may be employed, such as but not limited to, an overflow tank, an expansion tank, and a shunt tank.
The shunt tank in the engine cooling system accommodates the expansion of coolant in addition to providing a fluid connection to the fluid pump, which provides a positive pressure head to the fluid pump. This reduces the likelihood of cavitation in the fluid pump, due to excessive negative pressure in the fluid pump. It may be noted that if the coolant level in the shunt tank is not sufficiently high, the fluid pump may suck air bubbles into the fluid pump, leading to pump failure. To counter this phenomenon, a sufficient height of coolant is required to be maintained above an exit port, where coolant exits the shunt tank. This prevents air bubbles from being entrained in the coolant exiting the shunt tank and reduces the possibility of fluid pump failures. Notably, the height of coolant above the exit port, to the fluid pump, is required to be sufficient in all operating conditions, including when a machine is operating on an incline.
Conventional shunt tanks are largely horizontal in nature and the height of the tank is much less than the width or length. In certain operating conditions of the conventional shunt tanks, such as, when the machine is on an inclined terrain, the coolant level in the shunt tank is likely to be decreased at the exit port. In such situations, the fluid pump is likely to suck air bubbles, resulting in pump failure. Therefore, a significant amount of additional coolant volume is required to be maintained in conventional shunt tanks, to maintain the sufficient height of the coolant above the exit port. Additionally, the visibility of fluid level within the shunt tank is impaired due to the packaging of the radiator in the machine.
Alternate designs of conventional shunt tanks include a recessed compartment formed in a floor portion of the shunt tank. The exit port, where coolant exits the shunt tank to the fluid pump, is located in this recessed compartment. This maintains certain height of coolant above the exit port in all operating conditions, including when a machine is operating on an incline. However, as this design of the shunt tank has recessed compartment formed in the floor portion, the shunt tank may have a relatively greater height, after installation. This increases the overall height of the engine cooling system and reduces visibility from an operator cabin, which is positioned behind the engine cooling system.
United States Patent Application Publication 20040025813 discloses a front-end structure of a vehicle that includes a tank and a sight gauge mounted on one of the tank's faces. Although this disclosure discusses a compact front-end structure of the machine, the disclosure fails to provide a solution for prevention of cavitation, when the machine is stationed on an incline.

SUMMARY OF THE INVENTION

Various aspects of the present disclosure are directed towards a shunt tank for an engine cooling system of a machine. The engine cooling system includes a radiator with a radiator frame and a fluid pump. The shunt tank is disposed upstream to the fluid pump. The shunt tank includes a floor section, a first wall, a second wall, a third wall, a fourth wall, a lower compartment, a fluid conduit, and a sight gauge. The floor section mounts onto the radiator frame. The first wall, the second wall, the third wall, and the fourth are structured substantially uprightly on the floor section. The first wall is structured opposite to the second wall. At least one of the first wall and the second wall is arranged proximal to a lateral edge of the radiator frame and defines a gauge attachment portion. The third wall and the fourth wall extend between the first wall and the second wall. A tank interior with a first volume is defined by an enclosed space formed by the floor section, the first wall, the second wall, the third wall, and the fourth wall. The third wall includes a compartment attachment portion proximal to an interface between the third wall and the floor section. The lower compartment attaches to the compartment attachment portion and is in fluid communication with the tank interior. The lower compartment is structured and arranged to extend at least partially beyond the floor portion, towards the radiator frame. The lower compartment includes a fluid outlet and defines a second volume. The second volume is substantially less than the first volume of the tank interior. The fluid conduit fluidly connects to the fluid outlet and the fluid pump, to facilitate fluid communication between the shunt tank and the fluid pump. The sight gauge attaches to the gauge attachment portion and is visually accessible to indicate a level of a coolant fluid in the tank interior.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary machine installed with an engine cooling system, in accordance with the concepts of the present disclosure;

FIG. 2 is a schematic of the engine cooling system of FIG. 1, including a shunt tank of the engine cooling system, in accordance with the concepts of the present disclosure; and

FIG. 3 is a perspective view of the shunt tank of FIG. 2, including a partial section of the shunt tank illustrated in conjunction with a portion of a radiator of the engine cooling system of FIG. 1, in accordance with the concepts of the present disclosure.

DETAILED DESCRIPTION

Referring to FIG. 1, there is shown a machine 10. In an embodiment, the machine 10 is a large mining truck (LMT). However, aspects of the present disclosure may be extended to other construction machines, such as track-type tractors, hydraulic excavators, wheel loaders, motor graders, and large mining trucks. Moreover, an extension of the application of the present disclosure may be contemplated to stationery machines, such as generators, as well. Additionally, an applicability of the aspects of the present disclosure may be explored in domestic and commercial applications.
The machine 10 includes an operator cabin 12, which houses a number of control circuitry associated with the machine 10, to control a multiplicity of functional items associated with the machine 10. Further, the machine 10 includes an engine 14 (FIG. 2) and an engine cooling system 16. Although not limited to, the engine 14 (FIG. 2) may be a spark-ignition engine or a compression ignition engine. The engine cooling system 16 is adapted to cool the engine 14 (FIG. 2) and prevent over-heating of the engine 14 (FIG. 2). The engine cooling system 16 includes a radiator 18, which is exemplarily positioned in a radiator frame 20 disposed at a frontal end 22 of the machine 10, as shown.
Referring to FIGS. 1 and 2, the radiator 18 is in fluid communication with the engine 14 (FIG. 2). As is customary, a coolant is circulated through the engine 14 (FIG. 2) and the radiator 18 in a closed-loop manner, to facilitate cooling of the engine 14 (FIG. 2).
Referring to FIG. 2, the engine cooling system 16 is shown in conjunction with the engine 14. The engine cooling system 16 is in an active state, when the engine 14 is operative. The engine cooling system 16 is in an inactive state, when the engine 14 is inoperative. The engine cooling system 16 includes the radiator 18, a fluid pump 24, a thermostat 26, and a shunt tank 28. Further, fluid lines 30 are provided that are connected to each of these components, and which provide inter fluid communicability between each of these components.
The fluid pump 24 is a gear driven pump fluidly connected to the engine 14. The fluid pump 24 is disposed upstream to the engine 14, in a normal coolant flow direction, A. In the active state of the engine cooling system 16, the fluid pump 24 is actuated and supplies coolant to the engine 14 and the thermostat 26, in the normal coolant flow direction, A. Whereas, in the inactive state of the engine cooling system 16, the fluid pump 24 is inactive and a flow through the engine 14 is restricted.
The thermostat 26 is a thermally controlled selective flow interrupter that controls the flow of coolant within the fluid lines 30, in the active state of the engine cooling system 16. The thermostat 26 is fluidly connected to the engine 14, and is disposed downstream to the engine 14 in the normal coolant flow direction, A. Additionally, the thermostat 26 is fluidly connected to the fluid pump 24, in a bypass direction, C. Notably, the thermostat 26 switches between an open state and a closed state, based on a temperature of the inflowing coolant. As an example, if a temperature of the fluid exceeds a preset threshold, the thermostat 26 is adjusted to the open state. Conversely, if a temperature of the fluid falls below the preset threshold, the thermostat 26 is adjusted to the closed state. In the open state, the thermostat 26 facilitate a flow of coolant to the radiator 18, in the normal coolant flow direction, A. In the closed state, the thermostat 26 facilitates a flow of coolant to the fluid pump 24, in the bypass direction, C.
The radiator 18 is fluidly connected to both the fluid pump 24 and the thermostat 26, to facilitate a fluid communication with the engine 14, in a closed-loop manner. The radiator 18 is adapted to cool the coolant that flows through the radiator 18, such that the coolant can be reused and recirculated in the engine cooling system 16. In general, the radiator 18 includes a number of fin sections, which extracts heat from the coolant that flows through the radiator 18 and dissipate to the external environments. Various types of the radiator 18 may be contemplated, such as but not limited to, a forced-convection type radiator, a natural-convection type radiator, and/or a liquid cooled radiator.
The shunt tank 28 is an expansion tank fluidly connected to the radiator 18, and is disposed downstream to the radiator 18, in a coolant flow direction, B. Vent lines 32 are fluidly connected between the radiator 18 and the shunt tank 28. Moreover, the shunt tank 28 is in fluid communication with the fluid pump 24, and is disposed upstream to the fluid pump 24, with respect to the coolant flow direction, B. The shunt tank 28 is adapted to maintain a potential head in the fluid pump 24 of the engine cooling system 16.
Referring to FIG. 3, there is shown an enlarged view of the shunt tank 28 of the engine cooling system 16. The shunt tank 28 includes a floor section 34, a first wall 36, second wall 38, a third wall 40, a fourth wall 42, a roof section 44, a sight gauge 46, a lower compartment 48, and a fluid conduit 50.
The floor section 34 is attached to a top portion of the radiator frame 20. This attachment may be enabled by a fastening hardware, welding, and/or a rivet attachment. The floor section 34 includes a first edge 52, a second edge 54, a third edge 56, and a fourth edge 58. The first wall 36, the second wall 38, the third wall 40, and the fourth wall 42 are typically steel sheets structured substantially uprightly on the edges of the floor section 34.
The first wall 36 is attached to the first edge 52 of the floor section 34 and extends in a direction parallel to a length of the machine 10. Moreover, the first wall 36 is positioned proximal to a lateral edge 60 of the radiator frame 20 and includes a circular opening referred to as a gauge attachment portion 62.
The second wall 38 is attached to the second edge 54 of the floor section 34 and extends in a direction parallel to the length of the machine 10. Notably, the second wall 38 is positioned opposite to the first wall 36 of the shunt tank 28.
The third wall 40 is attached to the third edge 56 of the floor section 34 and extends between the first wall 36 and the second wall 38. Therefore, the third wall 40 extends in a direction perpendicular to the length of the machine 10. The third wall 40 defines a rectangular opening termed as a compartment attachment portion 64. More specifically, the compartment attachment portion 64 is defined at an interface between the third wall 40 and the floor section 34.
The fourth wall 42 is attached to the fourth edge 58 of the floor section 34 and extends between the first wall 36 and the second wall 38. Therefore, the third wall 40 extends in a direction perpendicular to the length of the machine 10. Notably, the fourth wall 42 is disposed opposite to the third wall 40. An attachment between each of the first wall 36, the second wall 38, the third wall 40, and the fourth wall 42 with the floor section 34 may be facilitated by a known attachment means, such as but not limited to, a weld attachment, an adhesive attachment, and/or, a seamless joint attachment. Although, the present disclosure contemplates an attachment of the first wall 36, the second wall 38, the third wall 40, and the fourth wall 42, to from the shunt tank 28. However, it may be contemplated that the shunt tank 28 may also be formed from a single steel sheet, by suitably cutting and bending the single steel sheet.
The roof section 44 covers and encloses each of the first wall 36, the second wall 38, the third wall 40, and the fourth wall 42. Notably, a tank interior 66 is defined by an enclosed space between the floor section 34, the first wall 36, the second wall 38, the third wall 40, the fourth wall 42, and the roof section 44. The tank interior 66 includes a first volume defined by the enclosed space between the floor section 34, the first wall 36, the second wall 38, the third wall 40, the fourth wall 42, and the roof section 44.
The sight gauge 46 is attached to the gauge attachment portion 62 defined on the first wall 36 of the shunt tank 28. The sight gauge 46 may be attached to the gauge attachment portion 62 by any known attachment means, such as, but not limited to, welding, an adhesive attachment, a thread attachment, and/or a press fit attachment. The sight gauge 46 may be a combination of a number of lenses arranged in a tubular structure, which facilitates indication of a level of the coolant in the tank interior 66.
The lower compartment 48 is attached to the compartment attachment portion 64, defined on the third wall 40 of the shunt tank 28. The lower compartment 48 is in fluid communication with the tank interior 66 by an internal communication port (not shown), and extends away from the tank interior 66. The lower compartment 48 is generally a supplementary chamber to collect a minimum volume of coolant from the shunt tank 28. The lower compartment 48 defines a second volume substantially less than the first volume of the tank interior 66. Moreover, the lower compartment 48 extends at least beyond the floor section 34 of the shunt tank 28, towards the radiator frame 20. This extension is along a vertical direction relative to the shunt tank 28. Such a configuration facilitates a base section 68 of the lower compartment 48, to be positioned at a relatively lower position than the floor section 34 of the shunt tank 28. Additionally, the lower compartment 48 includes a fluid outlet 70, which is in fluid communication with the fluid pump 24, via the fluid conduit 50. The fluid outlet 70 is an exit port of the shunt tank 28, from which the coolant exits the shunt tank 28.
The fluid conduit 50 is a coolant passage that facilitate a regular supply of coolant to the fluid pump 24. The fluid conduit 50 is fluidly connected between the fluid outlet 70 and the fluid pump 24, to facilitate a fluid communication between the shunt tank 28 and the fluid pump 24. Given the lower position of the lower compartment 48 relative to the shunt tank 28, a minimum height of coolant is generally maintained into the lower compartment 48 regardless of machine inclination, thus maintaining an uninterrupted communication of the coolant housed within the shunt tank 28 and the fluid pump 24.

INDUSTRIAL APPLICABILITY

In operation, an operator actuates the engine 14 of the machine 10. As the engine 14 is actuated, the engine cooling system 16 is set to the active state. In the active state of the engine cooling system 16, the fluid pump 24 is operative and supplies the coolant to the engine 14 and the thermostat 26, along the normal coolant flow direction, A. If the temperature of the coolant is below threshold limits, the thermostat 26 is in the closed state and facilitates a flow of coolant directly to the fluid pump 24. However, if the temperature of the coolant breaches the threshold limit, the thermostat 26 is in the open state and facilitates a flow of coolant to the radiator 18, which is then recirculated to the fluid pump 24. As the coolant temperature increases, it expands in volume. The expanded coolant flows through the vent lines 32 and enters into the shunt tank 28.
Furthermore, the operator may stop the engine 14, when not required to operate. In such situations, the engine cooling system 16 is set to the inactive state. In the inactive state of the engine cooling system 16, the fluid pump 24 is inactive and no flow of coolant is generated through the fluid pump 24. In such situations, as the coolant cools and contracts the shunt tank 28 level is reduced, but no coolant is lost from the engine cooling system 16. More specifically, the fluid conduit 50 and an intake side of the fluid pump 24 is supplied with the coolant from the shunt tank 28. The lower compartment 48 facilitates maintenance of a minimum height of coolant above the fluid outlet 70, and thus, enables an inlet interface of the fluid conduit 50 with the shunt tank 28 to be sufficiently below the coolant level housed within the lower compartment 48. In so doing, a dead volume of the shunt tank 28 is minimized and opportunity for air to enter the fluid conduit 50 is substantially avoided. Additionally, as the lower compartment 48 is installed on the third wall 40, the shunt tank 28 may have a relatively lesser height. This reduces the overall height of the engine cooling system 16 and facilitates a better view of work area from the operator cabin 12.
The above perspective is particularly applicable when the machine 10 is positioned on an incline and the engine cooling system 16. In such situations, the lower compartment 48 still facilitates the inlet interface of the fluid conduit 50 to be sufficiently below the coolant level housed within the lower compartment 48. This facilitates the intake side of the fluid pump 24 to be dipped with coolant housed in the shunt tank 28. This facilitates each of the fluid conduit 50 and the intake side of the fluid pump 24 to receive the coolant stored in the shunt tank 28. Therefore, the shunt tank 28 maintains the potential head for the fluid pump 24 and negates vulnerability to pump cavitation and other related damages, in all operating conditions of the machine 10. Moreover, as the sight gauge 46 is positioned along the lateral edge 60 of the radiator frame 20, an operator may note the level of coolant within the shunt tank 28 with relative ease.
It should be understood that the above description is intended for illustrative purposes only and is not intended to limit the scope of the present disclosure in any way. Thus, one of ordinary skill in the art will appreciate that other aspects of the disclosure may be obtained from a study of the drawings, the disclosure, and the appended claim.

Claims

What is claimed is:

1. A shunt tank for an engine cooling system of a machine, the engine cooling system including a radiator with a radiator frame and a fluid pump, the shunt tank being disposed upstream to the fluid pump, the shunt tank comprising:

a floor section mounted on the radiator frame;

a first wall and a second wall structured substantially uprightly on the floor section, the first wall being structured opposite to the second wall, wherein at least one of the first wall and the second wall is arranged proximal to a lateral edge of the radiator frame, and defines a gauge attachment portion;

a third wall and a fourth wall structured and arranged substantially uprightly on the floor section and extending between the first wall and the second wall, a tank interior with a first volume being defined by an enclosed space formed by the floor section, the first wall, the second wall, the third wall, and the fourth wall, the third wall including a compartment attachment portion proximal to an interface between the third wall and the floor section;

a lower compartment attached to the compartment attachment portion and in fluid communication with the tank interior, the lower compartment being structured and arranged to extend at least partially beyond the floor section towards the radiator frame, the lower compartment defining a second volume and including a fluid outlet, wherein the second volume is substantially lesser than the first volume of the tank interior;

a fluid conduit fluidly connected to the fluid outlet and the fluid pump to facilitate a fluid communication between the shunt tank and the fluid pump; and

a sight gauge attached to the gauge attachment portion and being visually accessible to indicate a level of a coolant fluid in the tank interior.