WO2024018301A1 - Thermostat pour système de refroidissement d'un véhicule - Google Patents

Thermostat pour système de refroidissement d'un véhicule Download PDF

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Publication number
WO2024018301A1
WO2024018301A1 PCT/IB2023/056306 IB2023056306W WO2024018301A1 WO 2024018301 A1 WO2024018301 A1 WO 2024018301A1 IB 2023056306 W IB2023056306 W IB 2023056306W WO 2024018301 A1 WO2024018301 A1 WO 2024018301A1
Authority
WO
WIPO (PCT)
Prior art keywords
thermostat
cooling fluid
wax module
flange
module
Prior art date
Application number
PCT/IB2023/056306
Other languages
English (en)
Inventor
Deepak Suryakant Kulkarni
Santosh Kanhoba Katkar
Shrishail Bhimasha Mosalgi
Ladkat Sitaram Hanumant
Original Assignee
Tata Motors Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tata Motors Limited filed Critical Tata Motors Limited
Publication of WO2024018301A1 publication Critical patent/WO2024018301A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P7/00—Controlling of coolant flow
    • F01P7/14—Controlling of coolant flow the coolant being liquid
    • F01P7/16—Controlling of coolant flow the coolant being liquid by thermostatic control

Definitions

  • Present disclosure relates to a field of automobile engineering. Particularly, but not exclusively, the present disclosure relates to a cooling system for an engine. Further, embodiments of the present disclosure relate to a thermostat of the cooling system for a vehicle.
  • a cooling system for a liquid-cooled internal combustion engine of a motor vehicle comprises a radiator for cooling a cooling fluid, and a bypass line configured to bypass the fluid flowing to the radiator when the temperature of the cooling fluid is low. Further, the cooling system comprises a cooling fluid pump for circulating the cooling medium through the radiator and/or the bypass line and the engine cooling jacket. A thermostat is configured with the cooling system and is provided for directing the flow of the cooling fluid to the radiator and/or the bypass line, depending on the temperature of the cooling fluid.
  • the thermostat operates due to heat released by the engine’s combustion.
  • the thermostat is usually constructed to include a thermostat wax module generally formed by wax.
  • the wax in the thermostat wax module (3) responds to the temperature of the cooling fluid in such a way that it melts at a predetermined temperature and moves in a backward direction to allow the passage of cooling fluid into the radiator. Once the cooling fluid is cooled to a lower temperature, in the radiator, the wax cools and solidifies, whereupon the thermostat wax module (3) moves forward so that the cooling fluid flows through the bypass line.
  • the temperature at which the wax starts to expand is referred to as start open temperature (SOT). At this temperature, the thermostat wax module (3) starts allowing the flow of cooling fluid into the radiator.
  • SOT start open temperature
  • thermostat wax module (3) The temperature at which the thermostat wax module (3) reaches the lowermost position and closes the bypass line is termed as full open temperature (FOT).
  • FOT full open temperature
  • thermostat lift The linear distance traveled by the thermostat wax module (3) from the SOT to the FOT due to the expansion of wax is termed as a thermostat lift.
  • Fig. 1 illustrates a schematic view of thermostat operation at various cooling fluid temperatures.
  • Fig. 2a shows the engine cooling fluid flow curve plotted for a conventional thermostat used in a small capacity engine. It can be observed from the plot that at 1 mm of thermostat lift, about 25 liter per minute (1pm) of the cooling fluid passes through the thermostat. Further, Fig. 2b shows the curve plot between the cooling fluid flow rate from the engine with the bypass line corresponding to the engine speed. It can be observed that the maximum cooling fluid flow is 25 1pm which is achieved at an engine speed of 4000 rpm. However, the maximum vehicle operating points are in the range of engine speed 1700-3000 rpm. Therefore, the problem associated with conventional thermostats is that maximum engine cooling fluid flow is passed through the thermostat with less than 1 mm thermostat lift as can be observed after comparing Figs. 2a and 2b.
  • full capacity cooling fluid flow is passing through even at less than 1 mm thermostat lift.
  • the thermostat as a part of the cooling system has a significant role in shortening warm-up time and regulating the engine at a proper temperature to achieve optimal performance. This phenomenon of full capacity cooling fluid flow passing through even at less than 1 mm thermostat lift further affects the warm-up rate and fuel consumption during the early discharge of the cooling fluid through the thermostat.
  • the present disclosure is directed to overcome one or more limitations stated above or any other limitations associated with the prior art.
  • a thermostat for a vehicle comprises a frame connectable to a flange to define a cavity.
  • a stem member which is connectable to the flange and configured to receive a thermostat wax module is provided.
  • the thermostat wax module is defined around the stem member and configured to receive cooling fluid.
  • at least one contact portion is defined on the thermostat wax module. At least one contact portion is in contact with the flange at a first position and the thermostat wax module expands upon contact with the cooling fluid and displaces the stem member to a second position to allow passage of cooling fluid into the flange.
  • At least one contact portion is a hollow cylinder positioned on the thermostat wax module.
  • At least one contact portion is a conical ring positioned on the thermostat wax module.
  • At least one contact portion is divided into an upper member and a lower member.
  • the thermostat comprises a resilient member configured around the thermostat wax module.
  • the frame has a protrusion to receive the resilient member.
  • the first position is when the thermostat wax module is blocking the flow of cooling fluid into the flange.
  • the second position is when the thermostat wax module is displaced on the stem member to allow the flow of cooling fluid into the flange.
  • a cooling system for a vehicle comprising a radiator fluidly connectable to an engine of the vehicle.
  • a thermostat housing is defined as an inlet duct, a first outlet duct, and a second outlet duct.
  • the inlet duct is fluidly connectable to the engine and the first outlet duct is fluidly connectable to the radiator.
  • a thermostat for a vehicle comprises a frame connectable to a flange to define a cavity.
  • a stem member which is connectable to the flange and configured to receive a thermostat wax module is provided.
  • the thermostat wax module is defined around the stem member and configured to receive cooling fluid.
  • at least one contact portion is defined on the thermostat wax module. At least one contact portion is in contact with the flange at the first position and the thermostat wax module expands upon contact with the cooling fluid and displaces the stem member to a second position to allow passage of cooling fluid into the flange.
  • the first outlet duct is fluidly connectable to the inlet duct and configured to supply the cooling fluid to the radiator.
  • the second outlet duct is fluidly connectable to the inlet duct and configured to supply the cooling fluid to the engine bypassing the radiator.
  • Figure 1 Prior art illustrates a schematic view of thermostat operation at various cooling fluid temperatures.
  • Figure 2a illustrates the engine cooling fluid flow curve plotted for a conventional thermostat.
  • Figure 2b illustrates the cooling fluid flow rate from an engine with the bypass line corresponding to the engine speed.
  • FIG. 3 illustrates a schematic diagram of a cooling system having a thermostat, in accordance with an embodiment of the present disclosure.
  • Figure 4 illustrates a front view of the thermostat, in accordance with an embodiment of the present disclosure.
  • Figure 5 illustrates a front view of the thermostat with a hollow cylinder, in accordance with an embodiment of the present disclosure.
  • Figure 6 illustrates a front view of the thermostat with a conical ring, in accordance with another embodiment of the present disclosure.
  • Figure 7 illustrates a schematic view of thermostat operation at various cooling fluid temperatures, in accordance with an embodiment of the present disclosure.
  • Figure 8 illustrates a schematic view of thermostat operation at various cooling fluid temperatures, in accordance with another embodiment of the present disclosure.
  • Figure 9 illustrates a plot of an engine cooling fluid flow with respect to a thermostat lift, in accordance with an embodiment of the present disclosure
  • Fig. 3 depicts a cooling system (10) for an internal combustion engine (12) of a vehicle.
  • the cooling system (10) comprises a cooling circuit provided in the vehicle and configured for cooling the internal combustion engine (12) by means of cooling fluid flowing in the cooling circuit.
  • the cooling fluid is in form of a liquid, preferably a mixture of water and glycol.
  • the cooling fluid is not only limited to a mixture of water and glycol but, may include other mixture of additives which is well known in the art.
  • the cooling system (10) comprises a radiator (14) coupled into the cooling circuit for cooling the cooling fluid.
  • the cooling system comprises a cooling fluid pump (13) for circulating the cooling fluid in the cooling circuit, and a thermostat (16).
  • the thermostat (16) is configured for controlling the flow of cooling fluid between the engine (12) and the radiator (14) to control the temperature of the internal combustion engine (12).
  • the cooling system (10) further comprises a thermostat housing (18) defined with an inlet duct (20), a first outlet duct (22), and a second outlet duct (24).
  • the inlet duct (20) is fluidly connectable to the engine (12) and the first outlet duct (22) is fluidly connectable to the radiator (14).
  • an outlet (12b) from the engine’s cooling ducts is connected to the inlet duct (20) of the thermostat (16).
  • the first outlet duct (22) from the thermostat (16) is connected to an inlet (14a) of the radiator (14).
  • An outlet (14b) from the radiator (14) is connected to an inlet (12a) to the engine’s cooling ducts.
  • the second outlet duct (24) from the thermostat (16) is connected to the inlet (12a) to the engine’s cooling ducts via a bypass line (44).
  • the bypass line (44) makes it possible for cooling fluid to be flown past the radiator (14).
  • the pump (13) is positioned before the inlet (12a) to the engine’s cooling ducts but may also be positioned at other positions in the cooling system (10) which are known in the art.
  • the cooling fluid which flows through the radiator (14) is cooled by air that absorbs heat against the radiator (14) when the vehicle is in motion.
  • the cooling system (10) can also comprise a fan (15) that is positioned so as to generate an airflow through the radiator (14).
  • Fig. 4 depicts a schematic view of the thermostat (16) according to an embodiment of the present disclosure.
  • the thermostat (16) comprises a frame (26) connectable to a flange (28) to define a cavity (C).
  • a stem member (30) is provided which is connectable to the flange (28) and configured to receive a thermostat wax module (36).
  • the thermostat wax module (36) is defined around the stem member (30) and configured to receive cooling fluid. Further, the thermostat wax module (36) is displaceable between an initial position and a final position for regulating the flow of cooling fluid from the inlet duct (20) to the first and second outlet ducts (22, 24).
  • the thermostat (16) further comprises a resilient member (34) which is configured to bias the thermostat wax module (36) at the initial position.
  • the thermostat wax module (36) is responsive to a predetermined temperature to act against the resilient member (34).
  • the resilient member (34) is configured around the thermostat wax module (36).
  • the thermostat wax module (36) comprises a wax expandable to relatively move the thermostat wax module (36) axially away from the initial position to the final position. The wax is configured in such a way that it acts upon the thermostat wax module (36) when it is exposed to thermal changes.
  • the thermostat wax module (36) comprises a top contoured seating profile (40) which is positioned between the inlet duct (20) and the first outlet duct (22), and a bottom contoured seating profile (42) which is positioned between the inlet duct (20) and the second outlet duct (24).
  • the thermostat housing (18) defines a cooling fluid passageway between the flange (28) and the thermostat wax module (36) configured to supply the cooling fluid to the radiator (14).
  • the thermostat (16) according to the embodiments of the present disclosure is aligned into the cooling circuit of the vehicle.
  • the thermostat wax module (36) is displaceable from the initial position in the direction of the final position against the action of the spring force of the resilient member (34).
  • the thermostat wax module (36) is accommodated in the thermostat housing (18) in such a way that the portion of the cooling fluid flowing towards the radiator (14) and/or the bypass line (44) comes into thermal communication with the wax of the thermostat wax module (36).
  • the thermostat wax module (36) is sealingly fastened by an O-ring seal (not shown), thereby reducing the risk of leakage.
  • the frame (26) has a protrusion (38) to receive the resilient member (34).
  • the top contoured seating profile (40) is positioned such that in its close position, i.e. the initial position of the thermostat wax module (36) closes the first outlet duct (22) of the thermostat (16). This prevents the cooling fluid from flowing to the radiator (14). Further, in an open position, i.e. when the thermostat wax module (36) is in between the initial position and the final position, the top contoured seating profile (40) allows the cooling fluid to flow through the radiator (14).
  • the bottom contoured seating profile (42) is positioned such that in its close position, i.e. the final position of the thermostat wax module (36), it closes the second outlet duct (24) of the thermostat (16). This prevents the cooling fluid from flowing through the bypass line (44). Further, in an open position, i.e.
  • the bottom contoured seating profile (42) allows the cooling fluid to flow in the bypass line (44).
  • the top and bottom contoured seating profiles (40, 42) are connected to the thermostat wax module (36) in such a way that when the top contoured seating profile (40) is in its closed position the bottom contoured seating profile (42) will be in its open position.
  • the constituents and characteristics of the thermostat wax module (36) are such that when the cooling fluid is at a predefined lower temperature, i.e. at a relatively lower engine load the thermostat wax module (36) remains firmly intact unit. In this situation, the top contoured seating profile (40) will be in its closed position and hence the bottom contoured seating profile (42) will be in its open position, with the result that the cooling fluid flows through the bypass line (44).
  • the constituents and characteristics of the thermostat wax module (36) are also such that when the cooling fluid is at a certain higher temperature which it will have at a relatively higher engine load, the wax of the thermostat wax module (36) melts.
  • a normal desired working temperature of the cooling fluid for small capacity engines is about 80 degrees, in which case the constituents of the thermostat wax module (36) such as wax, will begin to melt.
  • This temperature is referred to as start open temperature (SOT) at which the thermostat wax module (36) starts axially moving away from the initial position to the final position.
  • SOT start open temperature
  • FOT full open temperature
  • the linear distance from the initial position of the thermostat wax module (36) to the final position is termed as a thermostat lift.
  • the resilient member (34) acts as a restoring spring to move the thermostat wax module (36) back to its initial position.
  • the initial position is the position when the cooling fluid temperature drops below the predetermined temperature and the wax re-solidifies.
  • the present disclosure provides at least one contact portion (32) defined on the thermostat wax module (36) of the thermostat (16).
  • the contact portion (32) remains in contact with the flange (28) at a first position and as the thermostat wax module (36) expands upon contact with the cooling fluid. Further, the contact portion (32) displaces the stem member (30) to a second position to allow the flow of cooling fluid into the flange (28).
  • the first position is the position when the thermostat wax module (36) is blocking the flow of cooling fluid into the flange (28).
  • the second position is the position when the thermostat wax module (36) is displaced on the stem member (30) to allow the flow of cooling fluid into the flange (28).
  • At least one contact portion (32) is configured to abut the thermostat wax module (36) to prevent cooling fluid from flowing from the inlet duct (20) to the first outlet duct (22) as shown in Fig.4. At least one contact portion (32) facilitates the delay in cooling fluid from flowing to the first outlet duct (22).
  • the contact portion (32) is a hollow cylinder (46) positioned on the thermostat wax module (36).
  • the contact portion (32) is a conical ring (48) positioned on the thermostat wax module (36).
  • at least one contact portion (32) is divided into an upper member and a lower member.
  • Fig. 7 illustrates a schematic view of thermostat operation at various cooling fluid temperatures when the hollow cylinder (46) is positioned on the thermostat wax module (36) in accordance with an embodiment of the present disclosure.
  • the cooling fluid temperature is below the SOT
  • the hollow cylinder (46) restrains the cooling fluid passageway from flowing cooling fluid to the first outlet duct (22). Due to this, the cooling fluid gets delayed to flow towards the radiator (14) even though the thermostat wax module (36) is in the second position.
  • the hollow cylinder (46) positioned on the thermostat wax module (36) also does not obstruct the cooling fluid passageway, due to which the cooling fluid passageway is open. This allows the movement of the cooling fluid into the flange (28).
  • Fig. 8 illustrates a schematic view of the thermostat operation at various cooling fluid temperatures when the conical ring (48) is positioned on the thermostat wax module (36) in accordance with another embodiment of the present disclosure.
  • the cooling fluid temperature is below the SOT
  • the conical ring (48) restrains the cooling fluid passageway from flowing cooling fluid to the first outlet duct (22).
  • the conical ring (48) positioned on the thermostat wax module (36) also does not obstruct the cooling fluid passageway, due to which the cooling fluid passageway is open. This allows the movement of the cooling fluid into the flange (28).
  • FIG. 9 illustrates a comparative plot of an engine cooling fluid flow with respect to the thermostat lift obtained in the conventional thermostat and the thermostat which is in accordance with an embodiment of the present disclosure.
  • the thermostat lift is 0 mm and at least one contact portion (32) seals the flow of the cooling fluid towards the radiator (14).
  • the wax in the thermostat wax module (36) starts expanding and the thermostat wax module (36) moves in an axially away direction to a second position such that the cooling fluid flow is controlled by the at least one contact portion (32). This is indicated by point “E” in Fig. 9. Further, point “B” in Fig.9 shows the cooling fluid flow through the thermostat (16) towards the radiator (14) in the conventional thermostat.
  • the wax in the thermostat wax module (36) expands further and at least one contact portion (32) moves downward such that the gap between the flange (28) and the contact portion (32) is in the limiting condition of controlling the cooling fluid flow.
  • a third predetermined cooling fluid temperature i.e. between SOT and FOT
  • the wax in the thermostat wax module (36) expands further and at least one contact portion (32) moves downward such that the gap between the flange (28) and the contact portion (32) is in the limiting condition of controlling the cooling fluid flow.
  • point “F” in Fig. 9 shows the cooling fluid flow through the thermostat (16) towards the radiator (14) in the conventional thermostat.
  • the thermostat wax module (36) expands to the maximum. Further, at least one contact portion (32) moves to its final position.
  • the gap formed between the flange (28) and the contact portion (32) is such that it allows the flow of the cooling fluid to the radiator (14).
  • neither the contact portion (32) nor the thermostat wax module (36) controls the cooling fluid flow towards the radiator (14).
  • the thermostat lift is in the range of 7 to 8 mm. This is indicated by point “£)” in Fig. 9.
  • the cooling fluid flow through the thermostat (16) in the present disclosure is controlled right from the beginning as indicated in plot “A-E-F-D” in place of plot “A-B-C-D” obtained for the conventional thermostats.
  • the above-predetermined temperatures i.e., the first, second, third, and fourth may be in the predetermined range of the cooling fluid temperatures.
  • the present disclosure of controlling the flow of the cooling fluid by providing at least one contact portion (32) facilitates an enhanced and controlled cooling mechanism for the engine at the desired level.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Temperature-Responsive Valves (AREA)

Abstract

La présente invention concerne un thermostat (16) d'un système (10) de refroidissement dans un véhicule. Le thermostat se constitue d'une armature (26) susceptible d'être liée à une bride (28) pour définir une cavité (C). Un élément (30) de tige peut être lié à la bride (28) et est configuré pour recevoir un module (36) de cire de thermostat. Le module (36) de cire de thermostat est défini autour de l'élément (30) de tige et configuré pour recevoir un fluide de refroidissement. Le thermostat comporte en outre au moins une partie (32) de contact définie sur le module (36) de cire de thermostat. La partie (32) de contact est en contact avec la bride (28) dans une première position et le module (36) de cire de thermostat se dilate suite au contact avec le fluide de refroidissement et se déplace sur l'élément (30) de tige jusqu'à une seconde position pour permettre le passage de fluide de refroidissement dans la bride (28). Le thermostat (16) décrit facilite un système de refroidissement amélioré et commandé au niveau souhaité.
PCT/IB2023/056306 2022-07-22 2023-06-19 Thermostat pour système de refroidissement d'un véhicule WO2024018301A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IN202221042184 2022-07-22
IN202221042184 2022-07-22

Publications (1)

Publication Number Publication Date
WO2024018301A1 true WO2024018301A1 (fr) 2024-01-25

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10989100B1 (en) * 2020-03-27 2021-04-27 Thomas Kubsch Engine cooling system and thermostat thermal actuator with a degassing two-stage piston

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10989100B1 (en) * 2020-03-27 2021-04-27 Thomas Kubsch Engine cooling system and thermostat thermal actuator with a degassing two-stage piston

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