The invention relates to a method and an apparatus for transporting thermal energy produced in a motor vehicle.
Until now, the energy produced in vehicle parts in their operation mostly goes unused and is emitted without being controlled to the environment. Only in the case of the internal combustion engine is the thermal energy contained in its coolant circuit utilized to heat the passenger compartment, via a heating-type heat exchanger.
The object of the invention is to create a method and an apparatus by means of which the thermal energy produced in operation of the motor vehicle is utilized in such a way as to reduce the energy consumption of the motor vehicle.
This is attained by a method that is characterized by the follow steps:
an electronic component in the motor vehicle is cooled, and
the thermal energy dissipated upon cooling of the component is conducted onward to some other vehicle part to heat it.
The invention is furthermore attained by an apparatus which serves in particular to perform the method of the invention. The apparatus has an electronic component, which is coupled with a heat-dissipating line, and the line in turn is coupled to another vehicle part in such a way that thermal energy from the component is output to the vehicle part via the line.
In particular, the invention is employed to dissipate the thermal energy from so-called power electronics, that is, electronics characterized by high electrical consumption.
The invention is based on the recognition that the waste heat produced in the operation of electronic components has until now been completely unutilized in the motor vehicle and simply output to the ambient air. The power and number of electronic components and thus the quantity of heat to be dissipated from electronic components is increasing from one motor vehicle generation to the next. Furthermore, however, parts in the motor vehicle, and here the term xe2x80x9cpartsxe2x80x9d is not meant to be limited to a single part but instead to cover entire structural groups, are provided that require heat for their desired operation. While in the case of electronic components on the one hand, such applications as large-area cooling fins are provided for dissipating thermal energy to the ambient air, on the other, additional measures are taken to heat other vehicle parts. For instance, because of the increasing efficiency of internal combustion engines, to achieve a high level of heating comfort in diesel vehicles, it has meanwhile become necessary to provide supplementary electric heaters to heat the passenger compartment, but as a result both electrical and fuel consumption rise. Because of the higher demand for electrical energy in a motor vehicle, for instance, in future a 42-volt starter generator will be employed, whose power electronics, such as the pulse-controlled inverter, might have a heat loss of more than one kilowatt. By means of the invention, this energy could for instance be carried into the coolant circuit of the engine or directly into a heating-type heat exchanger for heating the passenger compartment.
Advantageous features of the invention will become apparent from the dependent claims.
Preferably, the dissipated thermal energy from the electronic component is conducted onward in controlled fashion to the vehicle part to be heated; that is, the quantity of heat supplied to the vehicle part is controlled, for instance in order to prevent the vehicle part from becoming overheated or to adjust it to its optimal temperature.
In a preferred embodiment, the coolant circuit of the component is assigned its own radiator. As a function of a predetermined allowable or desired maximum temperature of the component and/or a predetermined limit temperature of the vehicle part to be heated, the coolant circuit of the component is coupled to that of the vehicle part and/or to its own radiator. Situations are conceivable in which the dissipation of the thermal energy from the electronic component to the structural part to be heated is not sufficient to cool the component adequately. Then its own radiator must be turned on, by way of which thermal energy is output for instance to the environment. Furthermore, the vehicle part to be heated can also have an optimal temperature range that should not be exceeded or undershot, if performance is to be maintained. For instance, once an internal combustion engine has reached its optimal operating temperature, it should not be cooled down. However, if the temperature of a coolant, supplied from the coolant circuit of the component into the coolant circuit of the engine, were below the desired temperature in the coolant circuit of the engine, then coupling the two coolant circuits to one another would lead to an undesired additional cooling of the engine. Conversely, however, the radiator of the coolant circuit assigned to the component should be turned off if the engine has not yet reached its operating temperature. Specifically, then as much heat as possible should be supplied from the component to the coolant circuit of the engine, so that the latter will reach its optimal operating temperature as fast as possible.
To attain the aforementioned goals, it is also advantageous that the coolant circuits of the component and of the engine are decoupled from one another, and that preferably in addition the coolant circuit of the component supplies thermal energy to its own radiator, whenever the exit temperature of the coolant from the coolant circuit of the component is below a predetermined operating temperature of the engine, which the engine has just reached at that moment.
Furthermore, in one feature, the invention provides that the volumetric flow of coolant in at least one of the two coolant circuits be controlled as needed via at least one electric coolant pump integrated with the coolant circuit. Until now, mechanical pumps that are coupled with the engine have been used as coolant pumps. For optimal adaptation of the heat transport in a coolant circuit, however, an electric coolant pump is now preferably used, by which the heat transport is possible with precision and as needed inside the coolant circuit or between circuits that are coupled with one another.
In one feature, the volumetric flow in the coolant circuit of the engine is controlled as a function of the engine temperature and the load range of the engine in which the engine is at that moment.
The method of the invention is also employed when the engine is turned off, for instance in order to utilize the energy of the still-warm component to heat the passenger compartment.
The method of the invention is attractive particularly for hybrid engines, in which the internal combustion engine is frequently off, and in the meantime electric motors or other electronic components are in operation and produce heat.
The apparatus of the invention, in one feature, provides that the heat-dissipating line is part of a coolant circuit assigned to the component, which coolant circuit communicates with the coolant circuit of the engine. The coolant circuit of the component can furthermore also communicate directly with the heating-type heat exchanger, however, or can have its own heating-type heat exchanger. In these versions, using the heat of the component to heat the passenger compartment is a primary goal.
The coolant circuits of the component and of the engine can preferably be coupled to one another and decoupled again from one another, to achieve control of the heat transport.
To avoid the energy loss in heat exchangers, the coolant circuits of the component and of the engine preferably communicate in such a way that coolant from one coolant circuit can flow into that of the other; that is, fluidically, the coolant circuits partly merge with one another.