Internal-combustion engines – Cooling – With cooling of additional parts or materials
Reexamination Certificate
1998-08-13
2001-03-06
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Cooling
With cooling of additional parts or materials
C123S041490, C165S287000
Reexamination Certificate
active
06196168
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns a device for cooling and preheating, especially of transmission fluid, of an internal combustion engine, with an equalization tank, with at least one radiator, which is connected by means of an engine thermostat when a predetermined temperature is reached in the cooling loop, and with a water/oil heat exchanger.
The invention also concerns a method for cooling and preheating.
BACKGROUND OF THE INVENTION
Oil cooling often occurs with oil/air coolers, using thermostats that respond to corresponding oil temperatures. These solutions are certainly quite effective at smaller cooler sizes, but with greater cooling output and correspondingly larger coolers a situation results, in which unduly low oil temperatures occur in many operating states, which adversely effect fuel consumption and lifetime of the internal combustion engine.
For this reason, a switch has since been made to optimize the oil temperature, i.e., to cool or heat the oil, as required. For this purpose, an additional oil/water heat exchanger is integrated in the cooling loop, which is connected or disconnected as required by means of a thermostat that responds to oil temperature. These thermostats often must be activated with an electrical control. Although this group of solutions was to offer optimized oil temperature, it also entails significant costs on the equipment side.
Oil/water heat exchangers integrated in the normal water loop are also used for transmission fluid cooling, which are often incorporated in a water tank of the radiator, but also can be provided separately. Only cooling is achieved in this group of solutions, but not preheating or heating.
It is stated in DE-OS 41 04 093 that both rapid heating of the passenger compartment and rapid achievement of the operating temperature of the engine and transmission fluid are the problem in the starting phase of internal combustion engines. A virtual cooling management system has been proposed here to better deal with these partially contradictory constraints, in which a microprocessor is supposed to influence the output of the different heat exchangers, based on signals from a series of temperature sensors in the different loops. This installation appears to be quite expensive and has a complicated and therefore vulnerable technical structure.
SUMMARY OF THE INVENTION
With the presented state of the art as point of departure, the task of the invention is to offer an efficiently functioning, as well as compact and cost-effective arrangement, for cooling and preheating of operating fluids, especially transmission fluid, for internal combustion engines with which both additional heating of the transmission fluid can be achieved in the starting phase of the engine without a significant adverse effect on heating of the passenger compartment, and more efficient oil cooling is possible without having to use additional air- or water-cooled oil coolers. The corresponding method for cooling and heating will also be stated.
This task is solved according to the invention with the features mentioned in the Patent Claims. The device according to the invention has only a single water/oil heat exchanger, which can be used both for and cooling of operating fluids, especially transmission fluid. A valve unit is prescribed for this purpose, which controls the forward stream of the mentioned heat exchanger. In the heating phase the heat exchanger receives a cooling water stream branched off from the main cooling loop, rapidly heated by operation of the internal combustion engine. However, this amount is so small that heating of the internal combustion engine itself and heating of the passenger compartment are scarcely affected at all. On the other hand, in the cooling phase, the forward stream is formed by means of the same valve unit in the coolant side stream essentially from the low-temperature region of the radiator. Alternatively or additionally to the low-temperature region of the radiator, at least one additional low temperature cooler can be provided, which is connected after the first-named radiator in the side stream. Because of the low-temperature region, which can be accomplished by means of additional flow through part of the radiator, the water/oil heat exchanger obtains a cooling water stream that is about 10° C. lower so that the oil to water temperature difference is increased and the cooling action improved. Even higher temperature differences can be achieved with the separate low-temperature cooler. There is also a possibility of a space-saving arrangement independent of the radiator.
A transitional region between the heating phase and cooling phase is situated at a temperature of about 80 to 90° C., in which the forward stream of the heat exchanger from the equalization tank is mixed with the [stream] from the low-temperature region of the radiator or alternatively from to the separate low-temperature cooler. Thus, both transmission fluid cooling in all operating situations, and heating, are possible merely by means of this one heat exchanger.
The fact that a forward stream from the low-temperature region of the radiator, or from the separate low-temperature cooler, is mixed with a minimal continuous stream from the equalization tank, i.e., a stream of higher temperature, additionally contributes to optimization of the oil temperature. Unduly low oil temperatures with their adverse consequences, as occur in particular during oil/air cooling over large trips, are avoided.
The low-temperature region of the radiator is accomplished, as known, by the fact that at least one partition is arranged in at least one water tank, which forces part of the water flowing through the radiator to flow with a U-shaped or meandering flow through the radiator. An additional connection is prescribed in the water tank within the low-temperature region, which is connected to the flow channels to the oil/water heat exchanger via a valve unit. The valve unit is accommodated in a housing that can be flow-connected to the equalization tank and on which two flow channels for the heat exchanger are molded, one of which is connected to the low-temperature region of the radiator or to the separate low-temperature cooler, and the other connected to the equalization tank. The housing that includes the valve unit preferably consists of an upper and lower mounting connector, which are joined by means of a quick-change connector. The upper mounting connector is then molded directly in the bottom region of the equalization tank and the lower mounting connector forms a single plastic injection-molded part with the flow channels of the heat exchanger. The return channel of the heat exchanger and the return connection of the equalization tank, as well as the return connector leading to the coolant pump, are also designed as a single injection-molded component. All these features mean that a compact design is achieved, since the mentioned components can be mounted in the immediate vicinity, for example, on the fan housing enclosing the radiator. Lines requiring space are therefore superfluous. All the media connections are designed as quick-change connections, which has a favorable effect on installation and disassembly.
A method for cooling and preheating is provided with which the efficiency of cooling and preheating can be improved. It has turned out to be particularly effective if the switch point of the valve unit to cooling operation is set slightly, say, 5° C., below the switch point of the engine main thermostat. Overall, it has been shown that the dynamic control process from mixing of cooler or warmer cooling water is best influenced over the entire control range.
The Patent Claims are referred to for additional features significant to the invention. Additional advantages of the invention follow from the subsequent description of practical examples. For this purpose, reference is made to the figures.
REFERENCES:
patent: 2188172 (1940-01-01), Brehob
patent: 2435041 (1948-01-01), Hild
patent: 3134371 (1964-05-01), Crooks
patent: 385
Absmeier Christian
Brost Victor
Eckerskorn Winfried
Huemer Gerhart
Kalbacher Klaus
Castro Arnold
Modine Manufacturing Company
Wood Phillips VanSanten Clark & Mortimer
Yuen Henry C.
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