US20130192544A1

US20130192544A1 - Inline thermostat control systems and methods

Info

Publication number: US20130192544A1
Application number: US13/691,280
Authority: US
Inventors: Shaun A. King; Trevor K. Eva; Alan M. Murdock; Tyler J. Doucette
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-12-01
Filing date: 2012-11-30
Publication date: 2013-08-01

Abstract

A snowmobile coolant system that includes an engine outlet line, an engine inlet line, and an inlet thermostat. The engine outlet line provides coolant flow between an engine and a heat exchanger of the snowmobile. The engine inlet line provides coolant flow between the heat exchanger and the engine. The inlet thermostat is positioned in the engine inlet line and is operable between open and closed states based on a temperature of coolant flowing from the heat exchanger to the inlet thermostat.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of the filing date of U.S. Provisional Application No. 61/565,806, filed Dec. 1, 2011, and entitled INLINE THERMOSTAT CONTROL SYSTEMS AND METHODS, the disclosure of which is incorporated, in its entirety, by reference.

TECHNICAL FIELD

The present disclosure relates generally to engine coolant systems, and more specifically relates to snowmobile coolant systems.

BACKGROUND

Many types of engines include a thermostat and an outlet from the engine block that controls the flow of coolant from the engine block to a heat exchanger (e.g., a radiator) based on a temperature of the coolant exiting the engine block. When the coolant reaches a certain temperature, the thermostat opens to permit flow of the coolant to the heat exchanger to cool the coolant. The coolant returns to the engine block at an engine coolant inlet. When the engine is turned off, the coolant temperature within the engine block tends to spike because there is no flow of the coolant to the heat exchanger.
Further, the coolant sitting in the heat exchanger may significantly drop in temperature based on, for example, the ambient environmental conditions when the engine is restarted within a timeframe when the coolant within the engine block is still above the operating coolant temperature and the temperature of the coolant in the heat exchanger is below operating temperature, the thermostat remains open and the cold coolant is moved directly into the engine block. This cold coolant may cause the cylinders of the engine to contract thereby causing friction and other interference with the pistons. This friction may cause damage to the piston and cylinder. This damage may influence the performance of the engine.

SUMMARY

One aspect of the present disclosure relates to a snowmobile coolant system that includes an engine outlet line, an engine inlet line, and an inlet thermostat. The engine outlet line provides coolant flow between an engine and a heat exchanger of the snowmobile. The engine inlet line provides coolant flow between the heat exchanger and the engine. The inlet thermostat is positioned in the engine inlet line and is operable between open and closed states based on a temperature of coolant flowing from the heat exchanger to the inlet thermostat.
The snowmobile coolant system may include an outlet thermostat positioned in the engine outlet line and operable between open and closed states based on a temperature of coolant flowing from the engine to the outlet thermostat. The snowmobile coolant system may include a bypass line providing coolant flow between an outlet of the engine and the engine inlet line. The bypass line may provide constant flow between the outlet of the engine and the engine inlet line when the engine is running. The inlet thermostat may include at least one bleeder hole that provides coolant flow through the thermostat when the thermostat is in the closed state. The inlet thermostat may open and close at a temperature in the range of about 120° F. to about 160° F.
The snowmobile coolant system may include an inlet thermostat housing configured to house the inlet thermostat, wherein the inlet thermostat housing includes a housing outlet, a housing inlet, and a side inlet, wherein the side inlet has a smaller cross-sectional size than a cross-sectional size of the housing inlet. The snowmobile coolant system may include a bypass line extending from an outlet of the engine to the side inlet. The inlet thermostat housing may include first and second housing pieces, which when assembled together capture the inlet thermostat within the inlet thermostat housing.
Another aspect of the present disclosure relates to vehicle dual zone coolant system that includes first and second thermostats and a bypass line. The first thermostat is positioned in an outlet coolant line coupled in flow communication between a coolant outlet of an engine and a heat exchanger of the vehicle. The second thermostat is positioned in an inlet coolant line coupled in flow communication between the heat exchanger and a coolant inlet of the engine. The bypass line extends from the engine upstream of the first thermostat to the engine inlet line downstream of the second thermostat. The first and second thermostats may control coolant flow to and from the engine.
The heat exchanger may include a radiator. The vehicle may be a snowmobile and the heat exchanger may be exposed in a drive track tunnel of the snowmobile. The first and second thermostats may be operable to open and close at a temperature within a range of about 100° F. to about 160° F. The inlet thermostat may be carried by a two-part inlet thermostat housing. The two-part inlet thermostat housing may include a outlet, an inlet, and a side inlet, wherein the side inlet is connected in flow communication with the bypass line.
A further aspect of the present disclosure relates to a method of controlling coolant temperatures in a snowmobile. The method includes providing an inlet thermostat, an engine inlet coolant line, an engine outlet coolant line, and a bypass line, connecting the engine inlet coolant line to a heat exchanger outlet and an engine coolant inlet, and connecting the engine outlet coolant line to a heat exchanger inlet and an engine coolant outlet. The method also includes positioning the inlet thermostat in the engine inlet coolant line, coupling the bypass line to the engine outlet coolant line and the engine inlet coolant line downstream of the thermostat, and operating the inlet thermostat to control a temperature of coolant entering the engine coolant inlet.
The method may also include providing an outlet thermostat and positioning the outlet thermostat in the engine outlet coolant line. The inlet thermostat may include at least one bleeder hole configured to provide flow through the inlet thermostat when the inlet thermostat is in a closed state. Operating the inlet thermostat may include opening and closing the inlet thermostat based on a temperature of coolant received from the heat exchanger.
The foregoing and other features, utilities, and advantages of the invention will be apparent from the following detailed description of the invention with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate various embodiments of the present disclosure and are a part of the specification. The illustrated embodiments are merely examples of the present disclosure and do not limit the scope of the invention.

FIG. 1 is a side view of an example snowmobile having a coolant system in accordance with the present disclosure.

FIG. 2 is a schematic diagram of a coolant system and engine according to the prior art.

FIG. 3 is a schematic diagram of an engine and coolant system for a vehicle in accordance with the present disclosure.

FIG. 4 is a side view of an example inlet control valve of the coolant system of FIG. 3.

Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.

DETAILED DESCRIPTION

One aspect of the present disclosure relates to a coolant system that includes multiple thermostats. A first of the thermostats is positioned in a coolant output line extending from the engine block to the heat exchanger. A second of the thermostats is positioned in a coolant inlet line that extends from an outlet of the heat exchanger inlet to an inlet of the engine block. The first thermostat may control coolant flow to the heat exchanger by remaining closed until the coolant temperature within the engine block reaches a certain heated temperature (e.g., 125° F.). The second thermostat controls flow of coolant returning to the engine block by remaining closed until the temperature of the coolant returning from the heat exchanger reaches a certain heated temperature (e.g., 125° F.).
Another aspect of the present disclosure relates to an inlet control valve that controls the return flow of coolant to an engine block based on a temperature of the coolant. The inlet control valve may include the second thermostat mentioned above. The inlet control valve may be used with a bypass line that extends from a coolant outlet of the engine to a side inlet (also referred to as a bypass inlet) of the inlet control valve downstream of the second thermostat. The coolant primarily flows through the bypass line until the temperature of the coolant passing through the heat exchanger reaches a certain heated temperature. The inlet control valve may operate to provide a relatively slow mixing of the heated coolant delivered through the bypass line and cooled coolant from the heat exchanger at a location downstream of the second thermostat.
The coolant systems described herein may also be referred to as a dual zone coolant system. The dual zone coolant system may include a first zone that includes a coolant loop through the first and second thermostats. A second zone of the coolant system may be defined by the bypass.
In one example, a snowmobile 10 as shown in FIG. 1 includes an engine A and a coolant system 12. Coolant system 12 may include a heat exchanger C that is exposed within a track tunnel of the snowmobile. The heat exchanger C may be exposed to snow, ice, and ambient air in and around the snowmobile drive track that is significantly lower in temperature than a temperature of the engine A.
Referring to FIG. 2, the engine A and coolant system 12 of snowmobile 10 are shown schematically for purposes of explaining operation of a coolant system that does not include the inlet control valve or second thermostat discussed above. When the engine is started cold, the coolant recirculates within the engine A until the coolant reaches a threshold temperature (e.g., in the range of about 120° F. to about 145° F.). When the threshold temperature of the coolant is reached, a thermostat B of the coolant system opens to permit coolant to travel through an outlet line K to an inlet H of the heat exchanger C. The coolant cools to a lower temperature as it passes through the heat exchanger C. The cooled coolant flows out of an outlet H of the heat exchanger C and through an inlet line L to a coolant bottle or reservoir D. The coolant passes through the coolant bottle D and the inlet line L to an inlet O of the engine A. A water pump E may be interposed between the inlet line L and the inlet O of the engine A.
When the engine A is shut off after running at normal operating temperature, the thermostat B remains open because it is exposed to coolant at or above the threshold temperature (e.g., 125° F.). Because the engine is shut off and the coolant is no longer moving, the engine goes through a heat arc process that can raise the engine temperature to above 180° F. (e.g., 200° F. or higher). The coolant in the heated engine may be referred to as super heated coolant. In contrast, the coolant positioned in the heat exchanger C begins to rapidly cool because it may be exposed to, for example, snow, ice and relatively cold ambient temperatures where the snowmobile 10 is being used. This cooled coolant may be referred to as super cooled coolant. The temperature of the coolant in the heat exchanger C may drop below 80° F., and sometimes lower than 50° F.
When the engine A is restarted within a time period when the coolant within engine A is greater than the threshold temperature to maintain the thermostat B open, the thermostat B remains open so that cooled coolant is pushed through the heat exchanger. Typically, coolant in the heat exchanger moves on a first in/first out basis so that the super cooled coolant in the heat exchanger is forced through the inlet line L directly into the engine A. The super cooled coolant, when contacting the components of the hot engine, tend to cause the engine components (e.g., cylinders) to contract. This contraction may cause additional interference and friction of the moving components (e.g., friction between the piston and cylinder) that may cause damage to the engine components. Furthermore, when the super cooled coolant reaches the thermostat B, the super cooled coolant causes the thermostat B to close. When thermostat B closes, the cold coolant is trapped within the hot engine block.
In some examples, the timeframe from starting the hot engine until the cooled coolant is trapped within the engine is less than 10 seconds, and sometimes less than 5 seconds. The change in coolant temperature between the super heated coolant held in the heated engine before starting the engine and the super cooled coolant that becomes trapped in the engine after starting the engine can be in excess of 100° F., and in some cases greater than 150° F. This significant change in coolant temperature within the engine in a short period of time may result in the damage discussed above.
Referring to FIG. 3, an example coolant system 112 in accordance with the present disclosure may be used with the snowmobile 10. The coolant system 112 may control the flow of coolant entering back into the engine A to help avoid the large change in coolant temperature within the engine at the time of restarting a heated engine. Coolant system 112 may include an inlet control valve F and a bypass G. The inlet control valve F is positioned in the inlet line L between the outlet I of the heat exchanger C and the inlet O of the engine A. The bypass G provides a bypass of the heat exchanger C by directing at least some coolant exiting an outlet N of engine A to a location downstream of an inlet thermostat R of the inlet control valve F. While the schematic drawing of FIG. 3 shows the bypass at a separate outlet N from the outlet M in which the thermostat B is connected, other arrangements are possible in which the bypass G is connected to the same engine outlet as the thermostat B.
Referring to FIG. 4, an example inlet control valve F is shown in greater detail. The inlet control valve F includes a side inlet J, first and second housing members P, Q, an inlet thermostat R, an inlet S, and an outlet P. The inlet thermostat R may be captured within the inlet control valve F between the first and second housing members P, Q. Alternative constructions are possible wherein the inlet thermostat R is integrally formed within the inlet control valve F such as by being co-molded within a single piece housing of the inlet control valve. The first and second housing members P, Q may be connected in any desired manner including, for example, heat welding, sonic welding, laser welding, adhesives, snap-fit connections, interference fits, brackets, fasteners (e.g., bolts, screws and rivets), and straps. The connection between the first and second housing members P, Q may be permanent or may provide a releasable attachment.
The inlet thermostat R may include at least one bleeder hole U, V. The bleeder holes U, V may permit passage of some coolant through the inlet thermostat R when inlet thermostat R is closed. The inlet thermostat R remains closed until coolant being delivered from the heat exchanger C to the inlet thermostat R reaches a threshold temperature (e.g., temperatures in the range of about 100° F. to about 160° F., and more preferably about 130° F. to about 145° F.). In some arrangements, the inlet thermostat R may be rated as a 130° F. thermostat such that the inlet thermostat R opens and closes when exposed to coolant at a temperature of 130° F.
Although two bleeder holes U, V are shown in FIG. 4, inlet thermostat R may include any desired number of bleeder holes. The size and number of bleeder holes may be altered to help the operator control the rate of coolant flow through inlet thermostat R when inlet thermostat R is in a closed state. This rate of flow may determine at least in part an amount of time to mix the super cooled coolant positioned in the heat exchanger with the super heated coolant delivered through the bypass G from the heated engine A.
The side inlet J is positioned downstream of the inlet control valve F and connected in flow communication with the bypass G. In some arrangements, the side inlet J is integrally formed with one of the housing members P, G. In other arrangements, the side inlet is positioned in the inlet line L at a location separate from the inlet control valve F.
The side inlet J may be arranged at an angle of about 30° F. to about 60° F., and more preferably in the range of about 40° F. to about 50° F. relative to a length dimension of the inlet control valve F. In one example, the inlet diameter of the side inlet J is ⅝ inch and the diameter of a pass-through bore W of the inlet control valve F is about 1 inch in diameter. Typically, an inner diameter of inlet thermostat R is also about 1 inch. The inner diameter of the inlet and outlet lines L, K and the thermostat B may also be about 1 inch, while the bypass inner diameter may be about ⅝ inch. Adjusting the relative sizes between the flow paths of the coolant system 112 may help determine the ratio of flow through the bypass G versus through the inlet thermostat R.
Other arrangements may be made for bleeding predetermined amounts of coolant past the inlet thermostat R besides providing bleeder holes through the inlet thermostat R. For example, the housing of the inlet control valve may include a bypass passage that directs coolant around the inlet thermostat R. In some arrangements, a separate hose or tube may extend from a position upstream of the inlet thermostat R to a position downstream of the inlet thermostat R (e.g., a position at the inlet S to a position at the outlet T). The bypass around the inlet thermostat R may provide a maximum flow rate that is only a portion of the maximum flow rate through inlet thermostat R when inlet thermostat R is operating into an open position.
A difference in size between the internal diameter of the side inlet J and the bore W may create a venturi effect within the inlet control valve F downstream of the inlet thermostat R. The venturi effect may create a vacuum pressure condition at a downstream site of the inlet thermostat R that assists in drawing coolant through the bleeder holes U, V. This vacuum condition may assist in accelerating the rate of coolant flow through the bleeder holes U, V for a given cross-sectional size of the bleeder holes U, V. The increased flow rate resulting from the venture effect may permit use of smaller bleeder holes to obtain the same flow rate as if larger bleeder holes were used without the venturi effect and associated vacuum condition.
In some arrangements, the inlet thermostat R is held by a different structure than the inlet control valve F. For example, the inlet thermostat R may be held in a chamber or other structure that is part of the inlet line L, such as within a hose that defines a portion of the inlet line L. In another example, the inlet thermostat R is held in a portion of the water pump E such as within a housing of the water pump E or a separate housing or chamber that is attached to the water pump E. The inlet thermostat R may be position in flow communication between the water pump E and the engine inlet O. Alternatively, the inlet thermostat R may be positioned in flow communication between the outlet I of the heat exchanger C and the water pump E as shown in FIG. 3.
In other arrangements, the inlet thermostat F may be mounted directly to the engine A (e.g., adjacent to the engine inlet O) or to the heat exchanger C (e.g., adjacent to the outlet I of the heat exchanger C).
Referring again to FIG. 3, when the engine A is started from cold, coolant is recirculated through the engine A and through bypass G and the inlet line L until the coolant reaches a threshold temperature that operates the thermostat B into an open position (e.g., a temperature of about 125° F.). Typically, the inlet thermostat R remains closed because the coolant flowing from the heat exchanger C to the inlet thermostat R is below a temperature that would operate the inlet thermostat R into an open position (e.g., a temperature of about 125° F.). After the thermostat B is opened, the heated coolant from engine A pushes the super cooled coolant positioned in the heat exchanger through the inlet line L to the inlet thermostat R. This cooled coolant may pass through bleeder holes U, V to mix with the heated coolant delivered via bypass G and the side inlet J at a location downstream of the inlet thermostat R. The coolant continues to pass through bleeder holes U, V until the coolant being delivered from the heat exchanger to inlet thermostat R reaches an operation temperature that opens inlet thermostat R (e.g., a temperature of about 125° F.).
With both thermostats B, R operating in an open state, the coolant system may attain a steady state flow through the outlet line K and bypass G to the inlet line L. In some arrangements, the outlets M, N of engine A are configured such that about 60% of the coolant flows through thermostat B and about 40% of the coolant flows through bypass G during this steady state condition. Many other ratios are possible for the flow through thermostat B and bypass G including, for example, a 50/50 ratio, a 40/60 ratio, and an 80/20 ratio.
When the engine A is shut off after running at normal operating temperature, thermostat B and inlet thermostat R remain open. Typically, the engine goes through a heat arc process that can raise the engine temperature and the associated temperature of the coolant positioned in engine A to above 180° F., and sometimes greater than 200° F. In contrast, the coolant positioned in heat exchanger C may rapidly cool due to environmental conditions to which the heat exchanger C is exposed (e.g., snow, ice, and cold ambient temperatures). The temperature of the coolant in the heat exchanger may drop below 80° F., and sometimes lower than 50° F. because no coolant is moving through the heat exchanger C.
Upon restarting the engine within a timeframe in which the temperature of the coolant within engine A is greater than a threshold temperature for maintaining thermostat B in an open state, the super heated coolant from engine A is advanced through outlet line K and into heat exchanger C. This flow of heated coolant pushes the super cooled coolant held in heat exchanger C through the coolant bottle D to the inlet thermostat R. The cold temperature of the super cooled coolant operates the inlet thermostat into a closed position to prevent the cold coolant from passing through inlet line L to the engine A. Some of the super cooled coolant passes through bleeder holes U, V and mixes with the super heated coolant passing through bypass G and side inlet J into the inlet line L downstream of the inlet thermostat R.
In some arrangements, a time period in the range of about 30 seconds to about 3 minutes may elapse during which the super cooled coolant is able to mix within heat exchanger C and the inlet line L downstream of inlet thermostat R (e.g., via mixing provided by bleeder holes U, V) so that the coolant temperature delivered to the inlet thermostat R reaches a threshold level that operates the inlet thermostat R into an open position. This delayed timeframe for mixing of the different temperature coolants and exposing the engine block to portions of the super cooled coolant permit the engine block to adjust without undo constricting that may cause damage to the engine A as described above with reference to the prior art system of FIG. 2.
The examples described with reference to the attached figures relate primarily to a snowmobile coolant system. However, principles of the coolant systems disclosed herein may be applicable to other vehicles and engines. For example, the coolant systems disclosed herein, in particular the use of a thermostat at a coolant inlet of an engine, may be used with all terrain vehicles (ATVs), motorcycles, utility terrain vehicles (UTVs), watercraft (e.g., boats and personal watercraft (PWC)), automobiles, and engines of every type, size and fuel use.
The preceding description has been presented only to illustrate and describe exemplary embodiments of the invention. It is not intended to be exhaustive or to limit the invention to any precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be defined by the following claims.

Claims

What is claimed is:

1. A snowmobile coolant system, comprising:

an engine outlet line providing coolant flow between an engine and a heat exchanger of the snowmobile;

an engine inlet line providing coolant flow between the heat exchanger and the engine;

an inlet thermostat positioned in the engine inlet line and operable between open and closed states based on a temperature of coolant flowing from the heat exchanger to the inlet thermostat.

2. The snowmobile coolant system of claim 1, further comprising an outlet thermostat positioned in the engine outlet line and operable between open and closed states based on a temperature of coolant flowing from the engine to the outlet thermostat.

3. The snowmobile coolant system of claim 2, further comprising a bypass line providing coolant flow between an outlet of the engine and the engine inlet line.

4. The snowmobile coolant system of claim 3, wherein the bypass line provides constant flow between the engine outlet and the engine inlet line when the engine is running.

5. The snowmobile coolant system of claim 1, wherein the inlet thermostat includes at least one bleeder hole that provides coolant flow through the thermostat when the thermostat is in the closed state.

6. The snowmobile coolant system of claim 1, wherein the inlet thermostat opens and closes at a temperature in the range of about 120° F. and 160° F.

7. The snowmobile coolant system of claim 1, further comprising an inlet thermostat housing configured to house the inlet thermostat, the inlet thermostat housing having a housing outlet, a housing inlet and a side inlet, the side inlet having a smaller cross-sectional size than a cross-sectional size of the housing inlet.

8. The snowmobile coolant system of claim 7, wherein the inlet thermostat housing comprises two pieces configured to connect together.

9. The snowmobile coolant system of claim 7, further comprising a bypass line extending from the side inlet to an outlet of the engine.

10. The snowmobile coolant system of claim 7, wherein the inlet thermostat housing comprises first and second housing pieces, which when assembled together capture the inlet thermostat within the inlet thermostat housing.

11. A vehicle dual zone coolant system, comprising:

a first thermostat positioned in an outlet coolant line coupled in flow communication between a coolant outlet of an engine and an heat exchanger of the vehicle;

a second thermostat positioned in an inlet coolant line coupled in flow communication between the heat exchanger and a coolant inlet of the engine;

a bypass line extending from the engine upstream of the first thermostat to the inlet coolant line downstream of the second thermostat;

wherein the first and second thermostats control coolant flow to and from the engine.

12. The vehicle dual zone coolant system of claim 11, wherein the heat exchanger includes a radiator.

13. The vehicle dual zone coolant system of claim 11, wherein the vehicle is a snowmobile and the heat exchanger is exposed in a drive track tunnel of the snowmobile.

14. The vehicle dual zone coolant system of claim 11, wherein the first and second thermostats are operable to open and close at a temperature within a range of about 100° F. to about 160° F.

15. The vehicle dual zone coolant system of claim 11, wherein the second thermostat is carried by a two-part inlet thermostat housing.

16. The vehicle dual zone coolant system of claim 15, wherein the two-part inlet thermostat housing includes an engine outlet, a heat exchanger inlet and a side inlet, the side inlet being connected in flow communication with the bypass line.

17. A method of controlling coolant temperatures in a snowmobile, the method comprising:

providing an inlet thermostat, an engine inlet coolant line, an engine outlet coolant line, and a bypass line;

connecting the engine inlet coolant line to a heat exchanger outlet and an engine coolant inlet;

connecting the engine outlet coolant line to a heat exchanger inlet and an engine coolant outlet;

positioning the inlet thermostat in the engine inlet coolant line;

coupling the bypass line to the engine coolant outlet and the engine inlet coolant line downstream of the thermostat;

operating the inlet thermostat to control a temperature of coolant entering the engine.

18. The method of claim 17, further comprising providing an outlet thermostat and positioning the outlet thermostat in the engine outlet coolant line.

19. The method of claim 17, wherein the inlet thermostat includes at least one bleeder hole configured to provide flow through the inlet thermostat when the inlet thermostat is in a closed state.

20. The method of claim 18, wherein operating the inlet thermostat includes opening and closing the inlet thermostat based on a temperature of coolant received from the heat exchanger.