WO2017112619A1

WO2017112619A1 - Engine warmup method and system with longer coolant zero-flow interrupted with pulsed flow

Info

Publication number: WO2017112619A1
Application number: PCT/US2016/067656
Authority: WO
Inventors: Emily SHARPE; Andrew Sutherland
Original assignee: BorgWarner Inc
Current assignee: BorgWarner Inc
Priority date: 2015-12-22
Filing date: 2016-12-20
Publication date: 2017-06-29
Anticipated expiration: 2018-06-22

Abstract

A method for warming an internal combustion engine (11) includes starting the engine (11) with stagnant coolant disposed in the engine (11) coolant passageway(s) (31) and initiating a zero-flow or near zero-flow of additional coolant to the at least one passageway (31) for a first predetermined time period. Then, additional coolant if flowed or pulsed to the engine (11) for a second predetermined time period to replace the stagnant coolant with additional coolant. Then, the flow or pulse of additional coolant is stopped and another zero-flow or near zero-flow of coolant is initiated for a third predetermined time period.

Description

ENGINE WARMUP METHOD AND SYSTEM WITH LONGER COOLANT ZERO-FLOW INTERRUPTED WITH PULSED FLOW

BACKGROUND

Technical Field:

[0001] This disclosure relates generally to methods for warming an internal combustion engine. More specifically, this disclosure relates to a method that combines zero-flow of coolant to the engine and at least one pulsed or short flow of coolant to the engine for improved engine warmup.

Description of the Related Art:

[0002] Allowing the engine block of an internal combustion engine to warmup during a cold start condition increases fuel economy and decreases emissions. These benefits are due to a reduction in friction loss as the engine temperature rises to an efficient operating temperature range.

[0003] One known strategy for rapidly warming an engine during a cold start is blocking the flow of coolant to the engine or reducing the coolant flow to the engine as much as possible. In conventional vehicles with mechanically dash-driven water pumps and thermostats, coolant flow through the engine block begins immediately after the vehicle starts, even though cooling is not yet needed and is actually detrimental to the warmup process. By stopping or zero-flowing the coolant during the engine warmup, the stagnant coolant inside the engine heats quickly, which allows the engine metallic parts and engine oil to heat quickly as well. This faster warmup produced by blocking coolant flow reduces friction in the engine sooner, which is very valuable in terms of fuel economy and emissions. Faster engine warmup also improves other aspects of combustion, such as heating the injectors, improving carburization in the cylinders, better fuel atomization, etc. Known zero-flow techniques for engine warmup include deactivating the water (coolant) pump or closing an electronic coolant control valve.

[0004] While zero-flow of coolant during engine warmup helps to maximize fuel economy and reduce emissions, zero-flow of coolant that is too short may not fully warmup the engine during certain drive cycles, thereby compromising the fuel economy and emissions benefits. Further, zero-flow for too long risks increasing the engine temperature above the recommended limit, which may compromise the durability of the engine. Further, zero-flow for too long can cause boiling in the engine head and/or cause the cooling fans to activate. Boiling of the coolant greatly compromises heat transfer from the head to the coolant, which can lead to engine damage. Activation of the cooling fans consumes energy, thereby adversely affecting the fuel economy.

[0005] Typically, to avoid damage to the engine or other parts, manufacturers design engine to operate at a zero-flow of coolant for too short of a period of time, which means normal operating temperatures are not reached before the zero-flow ends, which causes some of fuel economy benefit to be lost. Further, when zero-flow ends, cold coolant is introduced into the engine, thereby dropping temperatures even farther from the normal operating temperature, which also causes some of the fuel economy benefit to be lost.

[0006] Accordingly, improved methods of warming internal combustion engines are needed.

SUMMARY OF THE DISCLOSURE

[0007] A method of warming an internal combustion engine having at least one passageway for the passage of coolant through the engine is disclosed. The method includes starting the engine with stagnant or near stagnant coolant disposed in the passageway and initiating a zero-flow or near zero-flow of additional coolant to the passageway. The method further includes waiting a first predetermined time period and then flowing additional coolant to the at least one passageway for a second predetermined time period to replace the stagnant or near stagnant coolant with additional coolant. The method further includes stopping the flow of additional coolant to the at least one passageway and initiating another zero-flow or near zero- flow of coolant to the passageway for a third predetermined time period. In addition, when the engine reaches a predetermined operating temperature range, the method includes circulating additional coolant through the at least one passageway.

[0008] Another method of warming an internal combustion engine having at least one passageway for the passage of coolant through the engine is disclosed. The method includes providing an engine with stagnant or near stagnant coolant disposed in the at least one passageway and starting the engine and preventing flow of additional coolant through the at least one passageway. The method includes waiting a first predetermined time period while the flow of additional coolant is prevented and then, after the first predetermined time period, pulsing additional coolant to the at least one passageway for a second predetermined time period to replace the stagnant or near stagnant coolant with additional coolant. After the second predetermined time period, the method includes stopping the pulsing of additional coolant to the at least one passageway and initiating another zero-flow or near zero-flow of coolant to the engine for a third predetermined time period. If the engine reaches a predetermined operating temperature range after the third predetermined time period, the method includes circulating coolant through the at least one passageway. If the engine has not reached the predetermined operating temperature range after the third predetermined time period, the method includes pulsing additional coolant to the engine for a fourth predetermined time period. The method further includes stopping the pulsing of additional coolant to the engine after the fourth predetermined time period and initiating another zero-flow or near zero-flow of coolant to the engine for a fifth predetermined time period. In addition, if the engine reaches the predetermined operating temperature during the fifth predetermined time period, the method includes circulating coolant through the at least one passageway.

[0009] A vehicle is disclosed which comprises an internal combustion engine having at least one passageway for the passage of coolant through the engine. The at least one passageway accommodates stagnant or near stagnant coolant before the engine is started. The vehicle further includes a controller that is linked to a coolant flow control device for controlling the coolant flow control device. The coolant flow control device is capable of stopping flow of coolant to the at least one passageway, is further capable of initiating continuous flow of coolant to the at least one passageway and is further capable of pulsing small amounts of coolant to the at least one passageway to replace the stagnant or near stagnant coolant with additional coolant. The controller includes a timer and is linked to at least one temperature sensor associated with the engine. When the engine is started, the controller is programmed to send a signal to the coolant flow control device to block flow of coolant to the at least one passageway, thereby leaving the stagnant or near stagnant coolant in the passageway after the engine starts. The controller is programmed to wait for a first predetermined time period before sending a signal to the coolant flow control device to pulse additional coolant to the at least one passageway for a second predetermined time period and to replace the stagnant or near stagnant coolant with additional coolant. After the second predetermined time period, the controller is programmed to send a signal to the coolant flow control device to stop the pulsing of additional coolant and to block flow of additional coolant to the engine for a third predetermined time period. If the controller receives a signal from the temperature sensor that the engine has reached a predetermined operating temperature range after the third predetermined time period, the controller is programmed to send a signal to the coolant flow control device to circulate coolant through the at least one passageway. However, if the controller receives a signal from the temperature sensor that the engine has not reached a predetermined operating temperature range after the third predetermined time period, the controller is programmed to send a signal to the coolant flow control device to pulse additional coolant to the at least one passageway for a fourth predetermined time period. After the fourth predetermined time period, the controller is programmed to send a signal to the coolant flow control device to stop the pulsing of additional coolant to the at least one passageway and to block flow of coolant to the engine for a fifth predetermined time period. And, if the controller receives the signal from the temperature sensor that the engine has reached a predetermined operating temperature range either during or after the fifth

predetermined time period, the controller is programmed to send a signal to the coolant flow control device to circulate coolant through the at least one passageway.

[0010] In any one or more of the embodiments described above, the first

predetermined time period is longer than the third predetermined time period, which is longer than the second predetermined time period.

[0011] In any one or more of the embodiments described above, the second predetermined time period is less than about 25 seconds. In a further refinement, the second predetermined time period is ranges from about two to about three seconds.

[0012] In any one or more of the embodiments described above, the first

predetermined time period is less than 15 minutes and the third predetermined time period is less than ten minutes.

[0013] In any one or more of the embodiments described above, the first

predetermined time period ranges from about three to about 5 minutes, the second predetermined time period ranges from about two to about three seconds and the third predetermined time period is less than about two minutes.

[0014] In any one or more of the embodiments described above, the circulating of additional coolant through the at least one passageway may further comprise circulating coolant through the at least one passageway in the engine, through a radiator and back through the at least one passageway in the engine. In a refinement, the radiator may be bypassed until the coolant reaches a desired temperature. [0015] In any one or more of the embodiments described above, the flowing of additional coolant to the at least one passageway for a second predetermined time period to replace the stagnant or near stagnant coolant with additional coolant includes activating a coolant pump for the second predetermined time period and then deactivating the coolant pump.

[0016] In any one or more of the embodiments described above, the flowing of additional coolant to the at least one passageway for the second predetermined time period to replace the stagnant or near stagnant coolant with additional coolant includes opening a coolant control valve for the second predetermined time period and then closing the coolant control valve.

[0017] In any one or more of the embodiments described above, after the third predetermined time period and before the circulating, if the temperature of the engine has not reached the predetermined temperature range, the method may further include flowing more additional coolant into the at least one passageway for a fourth predetermined time period and stopping the flow of the more additional coolant to the at least one passageway and initiating another zero-flow or near zero-flow of coolant to the at least one passageway for a fifth predetermined time period.

[0018] In any one or more of the embodiments described above, the second predetermined time period is long enough to replace the stagnant or near stagnant coolant with additional coolant.

[0019] In any one or more of the embodiments described above, the coolant flow control device may be a switchable coolant pump, which may be decoupled from the front end accessory drive (FEAD) to allow for zero-pump speed for zero-flow or near zero-flow of coolant.

[0020] In any one or more of the embodiments described above, the coolant flow control device may be an electric water pump, which may be turned on or off independent of engine speed. [0021] And, in any one or more of the embodiments described above, the coolant flow control device may be an electronic coolant control valve which can be maintained in a closed position during the first predetermined time period.

[0022] Other advantages and features will be apparent from the following detailed description when read in conjunction with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] For a more complete understanding of the disclosed methods and

apparatuses, reference should be made to the embodiment illustrated in greater detail on the accompanying drawings, wherein:

[0024] FIG. 1 schematically illustrates an engine and a coolant circulation system.

[0025] FIG. 2 graphically illustrates the engine coolant temperature at the coolant outlet of an engine for two different engine start/driving scenarios: (1) under the first scenario, the engine is operated under the NEDC standard for about 450 seconds with zero-flow of coolant to the engine followed by normal coolant circulation; and (2) under the second scenario, the engine is operated under the NEDC standard for about 450 seconds with zero-flow of coolant to the engine, followed by a pulsing or short flow of additional coolant to the engine to replace the stagnant or near stagnant coolant present when the engine was started, followed by another zero-flow or near zero-flow of coolant to the engine for about another 140 seconds.

[0026] FIG. 3 graphically illustrates the same two scenarios illustrated in FIG. 2 but the indicated temperature is measured at the middle top ring reversal point (MTRRP).

[0027] FIG. 4 graphically illustrates the same two scenarios illustrated in FIGS. 2 and 3, but the temperature is measured at the upper top ring reversal point (UTRRP).

[0028] FIG. 5 graphically illustrates the average exhaust/exhaust valve bridge temperatures for the two scenarios graphically illustrated in FIGS. 2-4. [0029] It should be understood that the drawings are not necessarily to scale and that the disclosed embodiments are sometimes illustrated diagrammatically and in partial views. In certain instances, details which are not necessary for an understanding of the disclosed methods and apparatuses or which render other details difficult to perceive may have been omitted. It should be understood, of course, that this disclosure is not limited to the particular embodiments illustrated herein.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0030] FIG. 1 illustrates a coolant circulation system 10 for an engine 11 that includes a head 12 and a block 13. The block 13 is fluidly coupled to a coolant flow control device in the form of a coolant pump 14, which includes an inlet 15. The coolant outlet 16 to the engine 11 may lead to another coolant flow control device in the form of a coolant control valve 17, which directs most of the coolant to the inlet 18 of the radiator 21. However, the coolant control valve 17 may also deliver coolant to the cabin heater 22, which then returns the cooled coolant to the pump inlet 15 and, optionally, to an expansion tank 23.

[0031] As an option, the outlet 24 of the radiator 21 may be fluidly coupled to the expansion tank 23. The expansion tank 23, also known as a degas tank, allows entrained air and gases in the coolant to be separated from the liquid coolant. After being degassed, liquid coolant is returned from the expansion tank 23 to the pump inlet 15. A pressure cap 25 may be employed to release air and gas entrained in the coolant. The expansion tank 23 may also be fluidly coupled to the coolant outlet 16 for removing entrained air or gas from the hot coolant before it enters the coolant control valve 17.

[0032] In addition to delivering hot coolant to the cabin heater 22, the coolant control valve 17 also directs the flow of coolant to the transmission fluid heater 26, which then returns the coolant through the valve 27 to the pump inlet 15 as shown in FIG. 1. The at least one passageway 31 that receives coolant from the coolant pump 14 may also be fluidly coupled to a turbocharger 32, which may return the heated coolant to the coolant outlet 16 upstream of the coolant control valve 17. The coolant pump 14 may be fluidly coupled to the cabin heater 22, the transmission fluid heater 26 and the control valve 27 as shown in FIG. 1. The coolant pump 14 may also be fluidly coupled to an engine bypass line 133 and control valve 33. Bypass line 133 enables coolant to flow through the rest of the system 10 while bypassing the engine 11 during a zero-flow condition.

[0033] The coolant pump 14 may be a switchable pump that can be coupled to or decoupled from the FEAD 35 to allow for zero-pump speed as the engine 11 is started. Alternatively, the coolant pump 14 may be a fully electric pump 14 that can be regulated by a controller 36, independent of the speed of the engine 11. The controller 36 may be linked to the coolant pump 14 and optionally to the FEAD 35 for turning the coolant pump 14 on and off. In an embodiment, control signals for the coolant pump 14 are sent by the controller 36. Further, the controller 36 may be linked to the coolant control valve 17, which can be maintained in closed position for a period of time after startup, thereby halting any circulating flow of coolant through the system 10.

[0034] A zero-flow of coolant after the engine 11 starts is important when trying to maximize fuel economy and reduce emissions. However, if the zero-flow of coolant is not long enough, the engine 11 may not be fully warmed up thereby compromising both fuel economy and emissions benefits. Longer zero-flow or near zero-flow of coolant time periods may allow the block 13 to be warmed up to its normal hot operating temperature, thereby increasing fuel economy, but there is a risk that the temperature of the engine 11 or various components will exceed certain temperature limits and limit the durability of the engine 11 and/or associated components. In addition to not exceeding temperature limits for certain components such as an exhaust-exhaust valve bridge, coolant temperatures during a zero-flow or near zero- flow condition inside the head 12 must be kept under a certain temperature to avoid excessive boiling of the coolant. Further, the coolant temperature during a zero or nonzero-flow condition must be maintained under a certain temperature to ensure that the cooling fans 38 are not activated. The fans 38 consume considerable amounts of energy, which adversely affects fuel economy. Accordingly, because of the above limitations, prior art methods do not heat the metallic components of the engine 11 to their normal operating temperatures before a prior art zero-flow or near zero-flow of coolant ends. Therefore, prior art methods do not optimize fuel economy. Further, when a prior art zero-flow of coolant ends, cold coolant is immediately introduced to the engine 11, thereby dropping metal temperatures quickly, which also compromises fuel economy.

[0035] This disclosure provides a solution to the above problems by carrying out a two-part or multiple-part zero-flow or near zero-flow coolant procedure wherein, after startup, coolant flow is blocked for a first predetermined time period and, after the first predetermined time period, the stagnant or near stagnant coolant disposed in the engine is replaced by additional coolant from the coolant pump 14. Those skilled in the art will be able to calculate the volume of the coolant passageway 31 or various coolant passageways 31 in the engine 11. Accordingly, one skilled in the art can easily determine the amount of additional coolant that should be flowed or pulsed into the engine 11 to replace the stagnant or near stagnant coolant disposed in the engine 11, which is heated during the first predetermined time period.

[0036] The additional coolant is pulsed or flowed into the at least one passageway 31 for a second predetermined time period. After the short flow or pulse of additional coolant has been carried out (or after the end of the second predetermined time period), the coolant flow control device, which may be the pump 14 or the control valve 17, is off or closed respectively and a second zero-flow or near zero-flow condition is carried out for a third predetermined time period, which is typically less than the first predetermined time period. The durations for the predetermined time periods will depend on the vehicle, engine and the drive cycle. For many vehicles and drive cycles, the first predetermined time period (first zero-flow) is typically less than 15 minutes, and may range from three to about five minutes. The third predetermined time period (second zero-flow) is typically less than ten minutes, and for many vehicles and drive cycles, may be less than two minutes. The second predetermined time period for the additional flow of coolant or the pulsing of coolant to the engine 11 is relatively short, and is typically less than 25 seconds, and for many vehicles and drive cycles, may range from about two to about three seconds After the second zero-flow or near zero- flow of coolant to the engine 11 during the third predetermined time period, if the engine 11 temperatures are not sufficient, a second additional flow or pulse of coolant may be carried out over a fourth predetermined time period, followed by another zero- flow or near zero-flow of coolant to the engine for a fifth predetermined time period. In other words, additional coolant may be pulsed to the engine 11 more than once between periods of zero-flow or near zero-flow. A temperature sensor 41 for the coolant is shown at the engine outlet 16, but could be disposed in a number of other locations, such as the radiator 21. The temperature sensor used for the data presented in FIG. 2 was disposed at the engine outlet 16. The temperature sensors 42, 43 measures metal temperatures. For example, the temperature sensor 42 could measure the middle top ring reversal point (MTRRP) while the temperature sensor 43 could measure upper top ring reversal point (UTRRP).

[0037] The disclosed method of periodically flowing or pulsing small amounts of coolant to the engine during zero-flow or near zero-flow was demonstrated on a test vehicle using an electronic coolant control valve 17 and the three temperature sensors 41, 42, 43. The results are illustrated graphically in FIGS. 2-5.

[0038] FIG. 2 graphically illustrates coolant temperatures. The plot 102 represents the vehicle operated under the EDC protocol with a zero-flow of coolant for about 450 seconds. Then, the NEDC protocol is carried out as the coolant is circulated. As shown in FIG. 2, the coolant temperature drops significantly at the 450 second mark as the coolant begins to circulate and more importantly, the coolant temperature in the engine 11 drops about 15°C below the stable operating temperature. Thus, the NEDC with 450 seconds of zero-flow represented by the plot 102 provides improved engine warmup until the time when the zero-flow is stopped and then the flow of fresh coolant through the at least one passageway 31 quickly drops the coolant temperature in the engine 11 below the desired temperature.

[0039] However, plot 103 of FIG. 2 illustrates the vehicle being operated under the NEDC protocol for 450 seconds with zero-flow of coolant followed by a short pulse of fresh or additional coolant to the at least one passageway 31 at the 450 second mark and then zero-flow of coolant is continued for another 115 seconds (from about 475- 590 seconds). As shown by the plot 103 in FIG. 2, the coolant temperature stays elevated in comparison to the plot 102 by temporarily ending the zero-flow at the 450- second mark and pulsing or flowing additional coolant into the engine 11 to replace the stagnant or near stagnant coolant disposed in the engine 11. Then, as shown by the plot 103, the second period of zero-flow raises the temperature of the coolant to a level slightly higher than the temperature at the end of the first zero-flow period (the 450 second mark). Thus, the process of operating under a zero-flow of coolant for a first predetermined time period, followed by a short flow or pulse of coolant into the engine to replace the hot stagnant coolant disposed in the engine, followed by another zero- flow or near zero-flow of coolant to the engine, provides a faster warmup and therefore improved fuel economy and reduced emissions.

[0040] The same protocols are graphically illustrated in FIGS. 3-5 with different temperature measurement locations. FIG. 3 illustrates the same two protocols but measures the average MTRRP exhaust side temperature in the upper portion of the FIG. 3 and the average MTRRP intake side temperature in the middle of the FIG. 3. The protocol that includes NEDC operation until 450 seconds with zero-flow followed by NEDC operation with normal coolant circulation is represented by the plot 202. Finally, the disclosed protocol, which includes NEDC operation for 450 seconds with zero-flow of coolant, followed by a short introduction or pulse of fluid into the engine and then followed by zero or non-zero-flow of coolant for another 115 seconds is represented by the plot 203. As shown, the disclosed method as represented by plot 203 provides the desired metal temperatures and avoids the dramatic drop-off after the zero-flow condition has stopped. On the intake side, the plot 302 represents the NEDC operation for 450 seconds with zero-flow, but without any pulse while the plot 303 represents the NEDC operation for 450 seconds with zero-flow, followed by a pulse of additional coolant and then followed by NEDC operation with zero-flow for another 115 seconds. Plot 303, which represents one disclosed method, maintains the elevated temperatures more effectively than the protocol represented by plot 302, which does not have a pulse of coolant to the engine after the initial zero-flow time period.

[0041] FIG. 4 graphically illustrates the two protocols graphically illustrated in FIGS. 2-3, but the temperature measurements made at the UTRRP exhaust side (top of FIG. 4) as well as the UTRRP intake side (middle of FIG. 4). The NEDC protocol for 450 seconds with zero-flow of coolant followed by normal coolant flow is represented by the plots 402 and 502. A disclosed method where the vehicle is operated under the NEDC protocol for 450 seconds with a zero-flow of coolant to the engine, followed by the short additional flow of pulse flow of coolant to the engine at 450 seconds and then followed by zero-flow of coolant for another 115 seconds is represented by the plots 403 and 503. As clearly shown in FIG. 4, like FIGS. 2-3, the pulse of coolant after the initial zero-flow time period followed by another zero-flow time period maintains the temperatures at more elevated levels when compared to the protocol with zero-flow but no pulse (plots 402, 502).

[0042] FIG. 5 illustrates the average exhaust-exhaust valve bridge temperatures for the two protocols (NEDC with 450 seconds of zero-flow— plot 602; NEDC with 450 seconds of zero-flow, followed by pulse of coolant to engine to replace stagnant coolant, followed by zero-flow— plot 603), neither of which result in the temperatures exceeding the maximum allowable of 220°C. INDUSTRIAL APPLICABILITY

[0043] A method is disclosed for improved warmup of internal combustion engines. After the engine 11 is started, coolant flow is blocked for a first predetermined period of time followed by a short coolant pulse or coolant flow into the engine to replace the stagnant or near stagnant coolant that has been residing in the engine since the engine startup. The pulse of coolant during the second predetermined time period is intended to replace the stagnant or near stagnant fluid and not begin recirculation of the coolant. Then, after the short flow of additional fluid or the pulse of additional fluid, another zero-flow time period is carried out for improved engine 11 warmup, improved fuel economy and reduced emissions. By periodically flowing small amounts of coolant or pulsing small amounts of coolant between periods of zero-flow, coolant temperatures remain elevated without overheating.

[0044] While only certain embodiments have been set forth, alternatives and modifications will be apparent from the above description to those skilled in the art. These and other alternatives are considered equivalents and within the spirit and scope of this disclosure and the appended claims.

Claims

CLAIMS:

1. A method of warming an internal combustion engine (11) having at least one passageway (31) for the passage of coolant through the engine (11), comprising: starting the engine (11) with stagnant or near stagnant coolant disposed in the at least one passageway (31) and initiating a zero-flow or near zero-flow of additional coolant to the at least one passageway (31); waiting a first predetermined time period; flowing additional coolant to the at least one passageway (31) for a second predetermined time period to replace the stagnant or near stagnant coolant with the additional coolant; stopping the flow of additional coolant to the at least one passageway (31) and initiating another zero-flow or near zero-flow of coolant to the at least one passageway (31) for a third predetermined time period.

2. The method of claim 1 wherein the first predetermined time period is longer than the third predetermined time period, which is longer than the second predetermined time period.

3. The method of claim 1 wherein the second predetermined time period is less than 25 seconds.

4. The method of claim 1 wherein the second predetermined time period ranges from about 2 to about 3 seconds.

5. The method of claim 1 wherein the first predetermined time period is less than 15 minutes.

6. The method of claim 1 wherein the third predetermined time period is less than ten minutes.

7. The method of claim 1 wherein the first predetermined time period ranges from about three to about five minutes, the second predetermined time period ranges from about two to about three seconds and the third predetermined time period is less than about two minutes.

8. The method of claim 1 wherein the flowing additional coolant to the at least one passageway (31) for the second predetermined time period to replace the stagnant or near stagnant coolant with additional coolant includes activating a coolant pump (14) for the second predetermined time period and then deactivating the coolant pump (14).

9. The method of claim 1 wherein the flowing additional coolant to the at least one passageway (31) for a second predetermined time period to replace the stagnant or near stagnant coolant with additional coolant includes opening a coolant control valve (17) for the second predetermined time period and then closing the coolant control valve (17).

10. The method of claim 1 further comprising, after the third predetermined time period and before the circulating, flowing more additional coolant to the at least one passageway (31) for a fourth predetermined time period, and stopping the flow of the more additional coolant to the at least one passageway (31) and initiating another zero-flow or near zero-flow of coolant to the at least one passageway (31) for a fifth predetermined time period.

11. The method of claim 1 wherein the second predetermined time period is long enough to replace the stagnant or near stagnant coolant with additional coolant.

12. A method of warming an internal combustion engine (11) having at least one passageway (31) for the passage of coolant through the engine (11), comprising: providing an engine (11) with stagnant or near stagnant coolant disposed in the at least one passageway (31); starting the engine (11) and preventing flow of additional coolant through the at least one passageway (31); waiting a first predetermined time period; pulsing additional coolant to the at least one passageway (31) for a second predetermined time period to replace the stagnant or near stagnant coolant with additional coolant; stopping the pulsing of additional coolant to the at least one passageway (31) and initiating another zero-flow or near zero-flow of coolant to the engine (11) for a third predetermined time period; if the engine (11) reaches a predetermined operating temperature range after the third predetermined time period, circulating coolant through the at least one passageway (31); if the engine (11) has not reached a predetermined operating temperature range after the third predetermined time period, pulsing additional coolant to the engine (11) for a fourth predetermined time period; stopping the pulsing of additional coolant to the engine (11) after the fourth predetermined time period and initiating another zero-flow or near zero-flow of coolant to the engine (11) for a fifth predetermined time period; when the engine (11) reaches a predetermined operating temperature range after the fifth predetermined time period, circulating coolant through the at least one passageway (31).

13. The method of claim 12 wherein the first predetermined time period is longer than the third predetermined time period, which is longer than the second predetermined time period.

14. The method of claim 12 wherein the second predetermined time period is less than 25 seconds.

15. The method of claim 12 wherein the second predetermined time period ranges from about two to about three seconds.