Method and apparatus for moderating the temperature of an internal combustion engine of a motor vehicle

Abstract

In an internal combustion engine of a motor vehicle, in order to shorten the cold-starting phase, it is provided that upon a shut off of the engine, essentially the entire amount of coolant is pumped out of a cooling system into a normally empty heat insulated reservoir, from which the coolant is fed back into the cooling system again upon subsequent start up of the engine.

Description

FIELD OF THE PRESENT INVENTION

The invention relates to a method for tempering an internal combustion engine of a motor vehicle, to which a cooling system with a coolant circulation for liquid coolant is assigned, and to a cooling system for the internal combustion engine.

BACKGROUND OF THE PRESENT INVENTION

After a cold start, until it reaches its operating temperature, an internal combustion engine has relatively poor properties, such as the release of major quantities of pollutants and high friction and hence wear. The deficiencies of a cold start can be avoided by adequately preheating the engine. The means proposed in the past for this purpose, particularly latent heat exchangers or heat insulated reservoirs built into the cooling systems, have so far not been deemed practical.

German Patent Disclosure DE 1451890, discloses the use of a pressure equalizing or venting tank as a reservoir, which communicates with the intake side of a coolant pump via a bypass line that can be blocked off by a blocking device. During normal operation, the coolant circulates through the venting tank. Upon a shut off of the engine, the blocking device is dosed to retain coolant in the reservoir, and it is opened upon engine starting, with the coolant from the tank being initially warmer than the rest of the coolant in the cooling system.

SUMMARY OF THE PRESENT INVENTION

The object of the invention is to enable preheating of an internal combustion engine in a cold start without having to increase the quantity of coolant in the cooling system.

This object is attained by feeding the coolant of the cooling system into a normally empty heat insulated reservoir upon a shut off of the engine, with essentially the entire amount of coolant in the cooling system being pumped into the reservoir, from which the coolant is later fed back into the cooling system upon subsequent start up of the engine.

As the reservoir is normally empty, no extra coolant is necessary to accommodate the reservoir and, therefore, so that the weight of the vehicle is not significantly increased. Also, the normally empty reservoir allows substantially the entire amount of coolant to be pumped into the reservoir, so that no coolant remains unused in the cooling system, thereby maintaining the temperature of the coolant that preheats the engine relatively high.

In a further feature of the invention, it is provided that a heat exchanger for a passenger compartment heating system and/or a heat exchanger for a transmission fluid cooling system and/or a heat exchanger for a motor oil cooling system is disposed in the cooling system, and the coolant is pumped from this entire cooling system into and out of the reservoir.

Briefly described, the method of the present invention is a method for moderating the temperature of an internal combustion engine of a motor vehicle during start up of the engine after the engine had previously been shut off, using a cooling system that circulates liquid coolant through the engine. The method of the present invention includes feeding the liquid coolant from the cooling system to a normally empty heat insulated reservoir upon shutting off the engine. Upon subsequent start up of the engine, the coolant in the reservoir is fed back to the cooling system. Preferably, substantially all of the liquid coolant is fed from the cooling system to the reservoir.

In the preferred embodiment, the feeding of coolant to the reservoir and the feeding of coolant from the reservoir is temporarily delayed.

In a preferred embodiment, the cooling system includes a passenger compartment heating system, a transmission fluid cooling system and a motor oil cooling system, and the liquid from the reservoir is fed to one or more or all of these systems. This feeding may be in any desired staggered delay sequence.

If desired, the feeding of liquid from the reservoir to the cooling system may temporarily bypass the radiator of the engine cooling system.

Briefly described, the apparatus of the present invention is a reservoir system used in conjunction with a cooling system for an internal combustion engine of a motor vehicle which has a conduit through which the liquid coolant is circulated between a radiator and an engine. The reservoir system includes a normally empty heat insulated reservoir, a reservoir conduit connecting the cooling system conduit with the reservoir, a pump in the reservoir conduit operable upon shut off of the engine to feed the liquid coolant from the cooling system into the reservoir. A valve in the reservoir conduit is operable upon start up of the engine for feeding of the liquid coolant from the reservoir into the cooling system. Preferably the reservoir has a capacity for containing substantially all of the liquid coolant in the cooling system.

In the preferred embodiment, the cooling system includes at least one of a passenger compartment heating system, a transmission fluid cooling system and a motor oil cooling system, and the reservoir system includes a return conduit connecting the reservoir to these heating and cooling systems. In this embodiment, the reservoir has a capacity for containing substantially all of the liquid coolant from these systems. Preferably a pump and a normally dosed valve are located in the return conduit and are operable upon start up of the engine to feed the coolant liquid from the reservoir to these systems.

If desired, a temperature sensitive bypass control valve may be located in the cooling system conduit upstream of the radiator to selectively divert the flow of coolant liquid from the reservoir to bypass the radiator and recirculate the cooling liquid to the engine.

Preferably, the reservoir is positioned at a level higher than the radiator and engine so that the cooling liquid may be fed from the reservoir by gravity.

Preferably there is a valve in the reservoir conduit that is operable to normally permit flow of liquid coolant to the reservoir and to prevent backflow. This valve is also openable upon start up of the engine to permit backflow of liquid coolant from the reservoir to the cooling system.

Also preferably, the reservoir conduit is connected to the cooling system conduit upstream of a cooling system pump that pumps coolant to the engine.

In the preferred embodiment, a pressure equalizing or vent tank is connected to the reservoir for passage of air thereto from the reservoir as coolant liquid is fed to the reservoir.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features, embodiments, and advantages of the present invention will become apparent from the following detailed description with reference- to the drawings, wherein:

FIG. 1 is a schematic illustration of a cooling system according to a preferred embodiment of the present invention; and

FIG. 2 is a schematic illustration of a cooling system according to another preferred embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The internal combustion engine 10 shown in FIG. 1 is located with a radiator 11 in a cooling system. A pump 12 pumps coolant to the engine 10 via a cooling system conduit 13. The coolant leaving the engine 10 flows to the inlet to the radiator 11 via a conduit 14. A bypass conduit 15 branches off from the conduit 14 and leads to a thermostat valve 16, through which the coolant, arriving from the engine 10, can be aspirated directly by the coolant pump 12 via a conduit 17. When the coolant is cold, the thermostat valve 16 keeps the communication open between the bypass conduit 15 and the conduit 17 that leads to the coolant pump 12, so that the coolant leaving the engine is returned directly to the engine 10 without passing through the radiator 11.

A conduit 18, which coming from the radiator 11 is connected to the thermostat valve 16. As soon as the coolant flowing in via the bypass conduit 15 has reached a predetermined temperature, the thermostat valve 16 begins to block off the bypass conduit and to open the conduit 18 to the radiator 11, so that then, more and more coolant arriving from the radiator 11 reaches the intake side of the coolant pump 12 via conduit 17. The thermostat valve 16 determines the quantities of coolant that are delivered through the bypass conduit 15 and the conduit 18 to the radiator 11. The engine 10 is thus heated to obtain an operating temperature within a minimum of time.

From the engine outlet conduit 14, a conduit 19 branches off and leads to a heat exchanger 20, which is a component of a passenger compartment heating system for the vehicle. The coolant flowing out of the heat exchanger 20 is delivered to the thermostat valve 16.

Via a ventilation valve, not shown, a conduit 22 is connected to a point at the highest level of the cooling system and leads to a pressure equalizing tank or vent 23 placed at or higher than this high point. The conduit 22, shown in dot-dashed lines, conducts essentially air or steam to the tank and any liquid collecting in the tank 23 is returned to the cooling system via a conduit 24, that connects the tank 23 to the connected cooling system intake side of the cooling system pump 12.

A normally empty heat insulated reservoir 25 is connected by a conduit 26 to the intake side of the cooling system pump 12 and is of a volumetric capacity to hold substantially the entire quantity of coolant present in the cooling system, i.e., in the engine 10, the radiator 11, the heat exchanger 20, the thermostat valve 16, and the conduits 13, 14, 15, 17, 18, 19 and 20. An electric-motor-driven pump 27 and an electrically switchable valve 28 are disposed in the conduit 26.

When the engine 10 is shut off, the pump 27 is turned on, and its operation is maintained for a predetermined length of time. This length of time is calculated such that within it, substantially the entire quantity of coolant in the cooling system can be aspirated and pumped to the reservoir 25, which until then is empty or in other words contains only air. Upon activation of the electric motor of the pump 27, the electrically actuated valve 28, which is, for example, a magnet valve, is also opened. The entire quantity of coolant is thus pumped into the reservoir 25, including the coolant in the radiator 11. The valve 28 prevents backflow of the coolant. The air contained in the reservoir 25 flows out via a conduit 29, which is connected to the pressure equalizing tank 23. In practice, it will be useful to dispose a blocking valve 30 in this conduit 29; this valve is likewise electrically switchable and is opened and closed together with the valve 28. While the coolant is being pumped out of the cooling system by the pump 27, replenishing air flows into the cooling system through the conduit 22.

Upon a start up of the engine 10, the valves 28 and 30 are opened. The cooling system pump 12, which may be an electric motor pump, but typically is operatively connected to the crankshaft of the engine 10, and which starts up with the engine 10, aspirates the coolant from the reservoir 25 and pumps it into the engine 10 and from there back into circulation in the cooling system. The reservoir 25 is disposed at a point located at a level higher than the cooling system pump 12, so that the coolant flows by gravity to the intake side of the pump 12. The valves 28, 30 close once the reservoir 25 has been emptied.

Preferably, a heat insulated, heavy-duty reservoir 25 is provided, such as a conventional thermos container that provides sufficient insulation so that over 24 hours only a temperature drop from approximately 100° C. to 60° C. takes place.

Since all the reservoir coolant from the cooling system is transferred to the reservoir, a correspondingly high quantity of heat is available for subsequent preheating of the engine 10. Moreover, the advantage is attained that the heat exchanger 20 for the passenger compartment heating system is also supplied with warm coolant upon a cold start of the engine 10, so that the temperature of the passenger compartment rises rapidly.

In a modification of the embodiment shown, the reservoir is formed in two sections or as two separate reservoirs with each section or reservoir alternatively connected with the pump 27, conduit 26 and valve 28, with a switching valve (not shown) for switching operation from one section or reservoir to the other. In this case, in a first stage, a chamber is filled with the quantity of coolant drawn from the engine, after which a switchover is made, and in the second stage, the second chamber is filled with coolant arriving from the radiator 11; this coolant is typically cooler than that arriving from the engine. This prevents the two quantities of coolant, which have different temperature levels from each other, from mixing.

An alternative preferred embodiment is illustrated in FIG. 2. It includes a cooling system for an internal combustion engine 10, a radiator 11, a coolant pump 12, a thermostat valve 16, and a heat exchanger 20 for the passenger compartment heating system of a vehicle, all similar to the embodiment of FIG. 1. This cooling system also includes a pressure equalizing or vent tank 23 with the ventilation conduit 22 and the return conduit 24 as in the embodiment of FIG. 1. However, the heat exchanger 20 of the passenger compartment heating system is not connected to the engine outlet conduit 14. Instead, via a separate conduit 31, it is subjected to coolant flowing out of the engine 10. A switchable regulating valve 32 is disposed in the conduit from the heat exchanger 20 to the mixing chamber of the thermostat valve 16.

Parallel to the heat exchanger 20 for the passenger compartment heating system of the vehicle, a heat exchanger 33 for a transmission fluid cooling system is provided in the cooling system. Both coolant and the fluid for an automatic transmission 34 belonging to the engine 10 flow through this transmission fluid heat exchanger 33. A heat exchanger 35 for the motor oil is also provided, and coolant from the engine and the motor oil flow through it as well.

In this design as well, a normally empty heat insulated reservoir 25a is provided, whose volume is designed such that it can receive the entire quantity of coolant that is present in the cooling system, including the passenger compartment heating system, the transmission fluid cooling system and the motor oil cooling system. The reservoir 25a is connected to the intake side of the coolant pump 12 via a conduit 26, which pump 27 can be operated by an electric motor. The conduit 26 also includes an electrically switchable valve 28, such as a magnet valve. The reservoir is connected to the venting tank 23 via a conduit 29 and a switchable valve 30.

Between the reservoir 25a and the conduit 31 that leads to the heat exchanger 20 for the passenger compartment heating system and to the heat exchanger 33 for the transmission fluid, there is a conduit 36 which includes a further switchable valve 37 and a pump 38 which can be driven by an electric motor. A check valve, not shown, that blocks a return flow into the engine 10 is provided in the conduit 31.

The triggering of the pump 27, the valves 28, 30, the valve 37 and the pump 38 is effected via a control unit 39. The control unit may be a control unit, especially designed for this purpose, for the storage system or a thermomanagement device or the overall engine control unit. This control unit 39 also triggers the regulating valve 32, which controls the inflow to the heat exchanger 20 for the passenger compartment heating system for the vehicle.

When the engine 10 is switched off, the control unit 39 switches the pump 27 on and opens the valves 28 and 30. The coolant is pumped practically entirely into the reservoir 25a, evacuating the cooling system. Air flows into the cooling system from the venting tank 23 via the conduit 22. The air present in the reservoir 25a flows into the venting tank 23 via the valve 30 and the conduit 29.

When the engine is switched on, the redelivery of the coolant to the cooling system can take place, in the manner already described in conjunction with FIG. 1. However, it is also possible to proceed in a staggered delay sequence and, for instance, by means of the control unit 39, first to open the valve 37 and to switch on the pump 38, such that first hot coolant is pumped into the heat exchanger 20 and the heat exchanger 33 and from there flows to the engine 10. The valve 30 is opened so that replenishing air can flow into the reservoir 25a. The valve 28 can be opened later, so that coolant is pumped out of the reservoir 25a into the engine 10 and from there into the radiator 11 with a delay after when the engine 10 is switched on.

For moderating the temperature of an internal combustion engine, in addition to the described method, it may be provided that upon shut off of the engine, the entire quantity of motor oil in the engine is pumped into a hot oil reservoir which until then is empty or in other words contains air. Upon a start of the engine, the motor oil is then pumped back into the engine, that is, into an oil cooler and the oil cooling conduits. The oil cooler may be a heat exchanger that is acted upon by air or preferably it may be a heat exchanger acted upon by the coolant fluid of the engine. The hot oil reservoir is disposed in a branch of the oil circulation and includes an electric-motor-driven oil pump. The branch is expediently connected to the intake side of the oil pump, the latter being part of the oil circulation. The hot oil reservoir is suitably disposed at a point which is at a higher level than the oil pump of the oil circulation system.

In view of the aforesaid written description of the present invention, it will be readily understood by those persons skilled in the art that the present invention is susceptible of broad utility and application. Many embodiments and adaptations of the present invention other than those herein described, as well as many variations, modifications, and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and the foregoing description thereof, without departing from the substance or scope of the present invention. Accordingly, while the present invention has been described herein in detail in relation to preferred embodiments, it is to be understood that this disclosure is only illustrative and exemplary of the present invention and is made merely for purposes of providing a full and enabling disclosure of the invention. The foregoing disclosure is not intended nor is to be construed to limit the present invention or otherwise to exclude any such other embodiments, adaptations, variations, modifications and equivalent arrangements, the present invention being limited only by the claims appended hereto and the equivalents thereof.

Claims

1. A method of moderating the temperature of an internal combustion engine of a motor vehicle during start up of the engine after the engine had previously been shut off, using a cooling system that circulates liquid coolant through the engine, and a normally empty heat-insulted reservoir, said method comprising feeding the liquid coolant from the cooling system to the reservoir upon shut off of the engine, upon subsequent start up of the engine feeding the coolant from the reservoir to the cooling system.

2. The method of claim 1 characterized by said feeding the liquid coolant to the reservoir feeds substantially all of the liquid coolant from the cooling system to the reservoir.

3. The method of claim 1 characterized by temporarily delaying the feed of coolant to the reservoir after the engine is shut off.

4. The method of claim 1 characterized by temporarily delaying the feed of coolant from the reservoir to the cooling system upon start up of the engine.

5. The method of claim 1, characterized by said feeding of the liquid coolant to the reservoir includes feeding liquid from at least one of a passenger compartment heating system, a transmission fluid cooling system and a motor oil cooling system, and said feeding of liquid from said reservoir includes feeding said liquid to said at least one of a passenger compartment heating system, transmission fluid cooling system and motor oil cooling system.

6. The method of claim 5 characterized by said feeding liquid from said reservoir feeds in a staggered delay sequence.

7. The method of claim 1 characterized by said feeding of liquid from the reservoir to the cooling system temporarily bypasses a radiator of the engine cooling system.

8. The method of claim 1 characterized by the reservoir being formed in two separate sections or two separate reservoirs, and said feeding the liquid coolant feeds coolant from the engine through the cooling system to one of said sections or reservoirs and feeds coolant from the radiator through the cooling system to the other of said sections or reservoirs.

9. In a cooling system for an internal combustion engine of a motor vehicle having a cooling system conduit through which liquid coolant is circulated between a radiator and the engine, a reservoir system comprising a normally empty heat-insulating reservoir, a reservoir conduit connecting said cooling system conduit with said reservoir, a pump in said reservoir conduit operable upon shut off of the engine to feed the liquid coolant from said cooling system into said reservoir, and a valve in said reservoir conduit operable upon start up of said engine for feed of the liquid coolant from said reservoir into said cooling system.

10. The reservoir system of claim 9 characterized by said reservoir having a capacity for containing substantially all of the liquid coolant in said cooling system.

11. The reservoir system of claim 9 characterized by a return conduit connecting said reservoir to at least one of a passenger compartment heating system, a transmission fluid cooling system and a motor oil cooling system for feeding liquid coolant from said reservoir to said at least one said passenger compartment heating system, said transmission fluid cooling system and said motor oil cooling system.

12. The reservoir system of claim 11 characterized by said reservoir having a capacity for containing substantially all of the liquid coolant in said cooling system and said at least one said passenger compartment heating system, said transmission fluid heating system and said motor oil cooling system.

13. The reservoir system of claim 11 characterized by a pump and a normally dosed valve in said return conduit operable upon start up of the engine to feed coolant liquid from said reservoir to said at least one passenger compartment heating system, transmission fluid cooling system and motor oil cooling system.

14. The reservoir system of claim 9 characterized by a temperature sensitive bypass control valve in said cooling system conduit upstream of said radiator and sensitive to the temperature of the cooling liquid to selectively divert the flow of coolant liquid to bypass the radiator and recirculate the cooling liquid to the engine.

15. The reservoir system of claim 9 characterized by said reservoir being positioned at a level higher than said radiator and said engine for feed of cooling liquid from said reservoir to the cooling system by gravity.

16. The reservoir system of claim 9 characterized by a valve in said reservoir conduit normally permitting flow of liquid coolant to said reservoir and preventing backflow, and operable upon start up of said engine to permit backflow of liquid coolant from said reservoir to said cooling system.

17. The reservoir system of claim 9 characterized by said reservoir conduit being connected to said cooling system conduit upstream of a cooling system pump that pumps coolant to the engine.

18. The reservoir system of claim 9 characterized by said reservoir being connected to a pressure equalizing tank of the cooling system for passage of air thereto from said reservoir as coolant liquid is fed to said reservoir.

19. The reservoir system of claim 8 characterized by said reservoir being formed in two separate sections or two separate reservoirs and said reservoir conduit being operable to feed coolant alternatively to one or the other of said sections or reservoirs.