Patent Application
20170328245
The present disclosure relates to an apparatus for heating lubricating oil for an internal-combustion engine.
At low ambient temperatures the higher viscosity of a lubricating oil that is being employed for lubricating the internal-combustion engine impairs the startability thereof. In addition, a cold start places a burden on the internal-combustion engine as a result of a rapid and uneven heating of individual components. Fuel consumption and pollutant emissions may also be elevated by the higher viscosity of the lubricating oil during a cold-start phase. In addition, a low power output (for instance, when idling) and a large volume of oil (for instance, in the case of utility vehicles) can lengthen the cold-start phase.
Consequently the object of the present disclosure is to make available a technical procedure that ensures the cold startability of an internal-combustion engine within a certain ambient-temperature range and shortens a cold-start phase.
According to one aspect of the disclosure, an apparatus is made available for heating lubricating oil for an internal-combustion engine. The apparatus includes a heat-exchanger arranged within an oil sump of the internal-combustion engine, which is flowed through or capable of being flowed through by a thermal medium for the purpose of emitting heat to lubricating oil in the oil sump, and a heat-source in fluidic communication with the heat-exchanger, which is designed to heat the thermal medium outside the oil sump and outside the internal-combustion engine.
The internal-combustion engine may include a combustion engine and/or a transmission. The lubricating oil may comprise engine oil and/or transmission oil. The oil sump may be arranged beneath an engine block of the combustion engine and/or beneath the transmission.
The apparatus may further include at least one sensor for registering at least one temperature. The apparatus may include a sensor for registering an actual temperature of the lubricating oil in the oil sump, a sensor for registering a forward-feed temperature in a forward feed of the heat-exchanger, and/or a sensor for registering the return-feed temperature in a return feed of the heat-exchanger.
The apparatus may further include a regulation system which is designed to regulate a power output of the heat-source in a manner depending on the at least one registered temperature. The power output of the heat-source can be regulated in such a way that the registered forward-feed temperature and/or the registered return-feed temperature of the heat-exchanger is/are higher than the actual temperature of the lubricating oil in the oil sump. The regulation system may be designed to bring about the heating of the lubricating oil by virtue of a return-feed temperature and/or a forward-feed temperature that is/are higher than the actual temperature.
The apparatus may further include a reservoir of the thermal medium, arranged outside the oil sump. The heat-exchanger and the reservoir may be in fluidic communication in a circuit of the thermal medium. The return-feed temperature can be registered between the heat-exchanger and the reservoir of the thermal medium.
The regulation system may further be designed to decrease or to limit the power output of the heat-source if the return-feed temperature is higher than a predetermined maximal temperature of the reservoir.
A suction point of a lubricating-oil circuit spatially assigned to the heat-exchanger may be arranged in the oil sump. For instance, the suction point may be arranged at the bottom of the oil sump beneath the heat-exchanger.
The heat-exchanger may comprise a plurality of plates arranged in parallel. The plates may be heat-conducting (for example, made of copper). The plates each exhibit a cavity into which the thermal medium flows. Alternatively or in supplement, the suction point may be arranged between the plates.
The plates may be spaced from one another. The plates may form interspaces. Each of the plates may be arranged in the oil sump below a desired level of the lubricating oil. The lubricating oil is able to flow in the interspaces. At least some of the oil-conducting interspaces may lead into the oil sump in such a way that the lubricating oil flows out of the oil sump directly into the oil-conducting interspaces. The interspaces can be flowed through and/or filled up by the lubricating oil. The plates may be wetted on both sides by the lubricating oil.
The heat-exchanger may include at least two connecting pipes. The thermal medium is able to flow in each of the connecting pipes. At a first connecting pipe the thermal medium can be supplied to the heat-exchanger (forward feed). At a second connecting pipe the thermal medium can be drawn off from the heat-exchanger (return feed). The connecting pipes of the forward feed and of the return feed can furthermore fasten the heat-exchanger mechanically within the oil sump.
The oil sump may include a peripheral connecting flange. The plates may be arranged parallel to a plane of the connecting flange. The heat-exchanger may include connecting pipes which are arranged within an opening, surrounded by the connecting flange, in the oil sump. The connecting pipes and/or the heat-exchanger may be arranged without direct contact with the oil sump. The heat-exchanger may be suspended in the oil sump.
Alternatively or in supplement, the oil sump may include a peripheral connecting flange, and the plates may be arranged perpendicular to a plane of the connecting flange. The heat-exchanger may include connecting pipes which lead through a side wall of the oil sump. The heat-exchanger may be fastened laterally in the oil sump. The connecting pipes may be fastened, for example screwed, to the side wall.
Furthermore, the plates of the heat-exchanger, which are parallel to one another, may be arranged at an angle relative to the plane of the connecting flange. The angle may amount to between 0° and 90°. The angle may be determined by the side wall. The side wall may be inclined relative to an opposite wall of the oil sump by the angle (or by an angle complementary to 90°). The plates of the heat-exchanger may be parallel to the side wall. For instance, the angle may be greater than or equal to 30°, and/or the angle may be less than or equal to 60°.
The suction point may be in alignment with the plates (or with some of the plates). The suction point may be arranged with respect to the heat-exchanger in such a way that a projection of the interspaces (or of one of the interspaces) parallel to the plates covers the suction point.
The thermal medium may comprise cooling water of the internal-combustion engine. The thermal medium may have been diverted from a cooling-water circuit of the internal-combustion engine. The forward feed and/or return feed of the thermal medium may form a lateral branch relative to the cooling-water circuit of the internal-combustion engine. The internal-combustion engine can act as a reservoir.
Features described above and below can be realized in any combination. Further features and advantages of the disclosure will be described in the following with reference to the appended drawings.
Shown are:
The apparatus 100 includes a heat-exchanger 104, arranged within an oil sump 102 of the internal-combustion engine, and a heat-source 106 in fluidic communication with the heat-exchanger 104. The heat-source 106 is arranged outside the oil sump 102. Irrespective of an operating temperature of the internal-combustion engine, the heat-source 106 emits heat to the thermal medium. Said thermal medium flows through the heat-exchanger 104 for the purpose of emitting heat to lubricating oil 108 in the oil sump 102.
A suction point 110 of an oil circuit is spatially assigned to, preferentially arranged beneath, the heat-exchanger 104. The heat-exchanger 104 is arranged completely below a desired level 112 of the lubricating oil 108 in the oil sump 102.
The apparatus 100 further includes a regulation system 120 for controlling a thermal power of the heat-source 106. The regulation system 120 is temperature-dependent and optionally time-controlled. The regulation system 120 is designed to ensure a startability of the internal-combustion engine within a predetermined ambient-temperature range, for instance at and/or above an ambient temperature of −46° C. To this end, the regulation system 120 controls the heat-source 106 for the purpose of heating the thermal medium of the heat-exchanger 104 until a minimum temperature of the lubricating oil 108 has been attained.
Optionally, the regulation system 120 registers an actual level of the lubricating oil 108, for instance by means of a float or by means of radar beams reflected from a surface of the lubricating oil 108. If the actual level is lower than the desired level, an output of thermal power from the heat-source 106 does not happen.
By virtue of the heat emitted by the heat-exchanger 104 to the lubricating oil 108, the temperature of the lubricating oil 108 is increased and the viscosity of the lubricating oil 108 is decreased. As a result, the internal-combustion engine can be started also at low ambient temperatures.
The heat-exchanger 104 comprises a plurality of parallel plates 114 which are each flowed through by the thermal medium. The thermal plates 114 are spaced from one another. Interspaces between adjacent thermal plates 114 are flowed around by the lubricating oil 108 for an effective transfer of heat from the thermal plates 114 to the lubricating oil 108.
By virtue of the thermal plates 114, a compact style of construction of the heat-exchanger 104 within the oil sump 102 is made possible. For instance, the surface area for the transfer of heat is enlarged by the plurality of thermal plates 114.
The thermal plates 114 have been manufactured from a material having high thermal conductivity, for instance having a thermal conductance (for example, at the minimum temperature of the lubricating oil 108 or at 20° C.) of at least 400 W/(m·K). By virtue of the high thermal conductivity of the thermal plates 114, the thickness thereof can be reduced, so that the volume of oil displaced by the heat-exchanger 104 is decreased without diminution of the effective surface area for the transfer of heat.
Optionally, the heat-exchanger 104 is employed within a high temperature range of the lubricating oil 108 for the purpose of cooling the lubricating oil 108. As a result, within differing temperature ranges of the lubricating oil 108 both functions, for heating and for cooling the lubricating oil 108, can be realized by means of the heat-exchanger 104 in the oil sump 102, without an additional heat-exchanger.
Whereas the first embodiment of the apparatus 100 shown in the perpendicular cross section of the oil sump 102 in
Besides the function of the heating of the lubricating oil for a cold start, any embodiment of the apparatus 100 may furthermore be employed for the purpose of controlling the temperature of the lubricating oil 108 during the operation of the internal-combustion engine at low ambient temperatures.
The lubricating oil can be employed for the purpose of lubricating a combustion engine and/or a transmission connected to said engine by the oil circuit.
The external heat-source 106 may be battery-operated. Alternatively, the external heat-source 106 comprises a combustion chamber into which engine fuel is injected and in which it is burnt.
The heat-exchanger 104 may be designated, corresponding to its geometry for instance, as a plate heat-exchanger or, corresponding to the dual function for instance, as an oil-cooler insert.
In the third embodiment, cooling water of an engine 130 which acts as a reservoir for the thermal medium serves as the thermal medium. Via a feeder 122 the cooling water is diverted from the cooling-water circuit of the engine 130 and heated in the external heat-source 106 to the forward-feed temperature in the forward feed 124 in accordance with the thermal power determined by the regulation system 120. For this purpose the heat-source 106 is connected to the connecting pipe 116 for the forward feed. The connecting pipe 118 for the return feed 126 is connected to a cooling-water reservoir of the engine 130. For the heating of the lubricating oil 108 in preparation for the cold start of the engine 130, the engine 130 serves as a reservoir for the thermal medium.
The regulation system 120 is connected to a first temperature sensor 121 which registers the oil temperature of the lubricating oil 108 in the oil sump 102. In a first implementation of the regulation system 120, the actual temperature of the lubricating oil 108 registered by means of the temperature sensor 121 determines the power output of the external heat-source 106.
Optionally, a second temperature sensor is arranged on the forward feed 124 for the purpose of registering the forward-feed temperature of the thermal medium. In a second implementation of the regulation system 120, a desired value for the forward-feed temperature in the forward feed 124 is determined on the basis of the actual temperature of the lubricating oil 108 registered by means of the first temperature sensor 121. The regulation system 120 regulates the power output of the external heat-source 106 on the basis of the difference between the desired value of the forward-feed temperature and the forward-feed temperature registered by the second sensor.
In the third embodiment shown in
The circuit 122, 124 and 126 of the thermal medium is driven by a pump which is likewise controlled by the regulation system 120. The pump for the thermal medium is arranged in the feeder 122, for instance.
As an alternative to or in supplement to the cold start, the apparatus 100 can also be employed in operation of the engine 130 for the purpose of controlling the temperature both of the lubricating oil 108 and of the cooling water of the engine 130. In the course of operation as a heat-retaining apparatus, according to the third embodiment in
In the case of regulated operation of the external heat-source 106 in operation of the engine 130, the oil temperature and/or the temperature of the thermal medium (that is to say, of the cooling water) is/are monitored by the regulation system 120. The external heat-source 106 is switched on by the regulation system 120 if a defined temperature value is fallen below.
The apparatus 100 for heating lubricating oil for an internal-combustion engine, in particular the heating function and/or heat-retaining function thereof, can be employed in a vehicle (for instance, a utility vehicle) or in an engine 130 being operated when stationary. The utility vehicle may be, in particular, a military vehicle. The heat-retaining function can intervene, for instance, for the purpose of ensuring a minimum temperature of the lubricating oil 108 (and, where appropriate, of the cooling water) whenever the engine 130 is idling or is only loaded slightly.
In the further development of the second embodiment shown in
The oil sump 102 exhibits a peripheral mounting flange 132 with a plurality of peripherally arranged bores 133 which by virtue of, in each instance, an indentation in the oil sump 102 are accessible from outside the oil sump 102 for the purpose of mounting the oil sump 102. In the first embodiment, the thermal plates 114 are arranged in the oil sump 102 parallel to the plane of the peripheral flange 132. In the second embodiment, the thermal plates 114 are arranged perpendicular to the plane of the peripheral flange 132.
The suction point 110 may be in alignment with one of the thermal plates 114, so that the oil 108 flows through the interspaces between the thermal plates 114 immediately before it enters the suction point 110.
The inclination of the side wall 140 may correspond to an extraction bevel for a manufacture of the oil sump 102 by casting. The side wall 140 and the parallel thermal plates 114 may be inclined by an angle between 0° and 5° relative to the vertical (corresponding to an angle 142 between 85° and 90°). For instance, the inclination may amount to 2° to 3° (corresponding to an angle 142 of 87° to 88°). The oil sump may be an aluminium casting.
As a result, oil 108 circulating in the oil sump 102 is able to flow through the interspaces between the thermal plates 114 by reason of the circulatory motion in the oil sump 102 for the effective exchange of heat with the thermal medium. In particular, a through-flow direction of the thermal medium (from the forward feed connecting pipe 116 to the return feed connecting pipe 118) in the heat-exchanger 104 may be opposite at the location of the heat-exchanger 104 to the direction of flow of the circulating oil 108. An oil pump can propel the circulation of the oil 108.
Although the present disclosure has been described with respect to exemplary embodiments, for a person skilled in the art it is evident that various changes may be made and equivalents may be used as substitutes. Furthermore, many modifications may be made in order to adapt a certain situation or a certain material to the teaching of the disclosure. Consequently the disclosure is not restricted to the disclosed embodiments but encompasses all embodiments that fall within the scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102016005881.1 | May 2016 | DE | national |
