Engine cooling system for a motor vehicle engine

Abstract

Engine cooling system designed for a motor vehicle engine, with a heat-generating engine block (12), a heat pipe (14) directly thermally coupled to the engine block (12) for the removal of heat and an air conditioning unit (18) provided for temperature control of a passenger compartment (20) of the motor vehicle, wherein the air conditioning unit (18) has an air duct (16) provided for supplying air into the passenger compartment (20) and the heat pipe (14) extends into the air duct (16) for tempering the air.

Description

[0001] The invention relates to an engine cooling system for a motor vehicle engine, with the aid of which the motor vehicle engine can be cooled.

[0002] From DE 28 00 265 A1 it is known to supply part of the heat generated in an internal combustion engine, which is present as latent heat in a cooling water flow or exhaust gas flow, via a heat pipe and an intermediate heat accumulator to a room heat exchanger of an air conditioning unit in order to temper the air in a passenger compartment.

[0003] From DE 30 03 154 A1 a heat pipe for heating a door of a motor vehicle is known.

[0004] From DE 10 2009 049 196 A1 a heat pipe is known for dissipating heat from highly stressed electrical components such as LED headlights to a surrounding body of a motor vehicle.

[0005] From EP 0 189 624 B1 it is known to use heat from an exhaust pipe for heating air flowing into the interior of a motor vehicle with the aid of a heat pipe.

[0006] From DE 10 2009 057 163 A1 it is known to use a heat pipe as an evaporator in a cooling device for cooling a motor vehicle battery.

[0007] From DE 25 51 911 A1 it is known to use a heat pipe for heating air flowing into the interior of a motor vehicle.

[0008] From DE 2 756 119 A1 it is known to use the waste heat of an internal combustion engine in a heat exchanger to control the temperature of a passenger compartment of a motor vehicle.

[0009] From DE 10 2009 051 298 A1 it is known to use a heat pipe for cooling a fuel cell of a motor vehicle.

[0010] From JP H06-35 871 U it is known to dissipate heat from a ship's combustion engine using a seawater-cooled heat pipe.

[0011] There is a constant need to be able to cool a vehicle engine quickly and efficiently.

[0012] The object of the invention is to show measures that enable rapid and efficient cooling of a motor vehicle engine.

[0013] The object is achieved according to the invention by an engine cooling system having the features of claim 1. Preferred embodiments of the invention are specified in the subclaims and the following description, which may each individually or in combination represent an aspect of the invention.

[0014] According to the invention, an engine cooling system is provided for a motor vehicle engine of a motor vehicle, comprising a heat-generating engine block, a heat pipe thermally coupled directly to the engine block and configured to dissipate the heat, and an air conditioning unit configured to control the temperature of a passenger compartment of the motor vehicle, wherein the air conditioning unit has an air duct configured to supply air into the passenger compartment, and the heat pipe projects into the air duct to control the temperature of the air.

[0015] The heat pipe can have a working medium that can be evaporated by the heat of the engine block and condensed in the air duct of the air conditioning unit, whereby the condensed working material can be transported back to the engine block by gravity and / or with the help of capillary forces. This makes it possible to cool the engine block and use the heat of the engine block to heat the fresh air supplied to the passenger compartment, so that less heat output from the air conditioning unit is required to regulate the temperature in the passenger compartment of the motor vehicle. This can reduce the energy consumption for the air conditioning unit and also use the energy generated by chemical combustion in the motor vehicle engine, which generates the heat in the engine block of the motor vehicle engine, for air conditioning. The efficiency of the fuel supplied to the motor vehicle engine can therefore be improved in the overall consideration of the motor vehicle.

[0016] In addition, the heat pipe is directly thermally coupled to the engine block, i.e., without an intermediate heat transfer medium between the engine block and the heat pipe. The heat pipe can, for example, rest with its outer side against the material of the engine block, so that heat can be transferred from the engine block to the heat pipe solely by conduction and without convective heat transfer with the aid of an intermediate heat transfer medium. This avoids thermal resistance at the phase boundaries between the solid body of the engine block on the one hand and the heat pipe on the other, and the otherwise provided fluid heat transfer medium. Instead of using cooling water from a water cooler for the vehicle engine and / or an exhaust gas stream from the vehicle engine as the intermediate heat transfer medium between the engine block and the heat pipe, the heat pipe is in direct contact with the engine block.Due to the direct thermal connection of the heat pipe to the engine block, heat transfer resistance caused by an intermediate heat transfer medium can be avoided, thus enabling fast and efficient cooling of the vehicle engine.

[0017] The engine block can, for example, have a recess into which the heat pipe can be inserted with surface contact. The heat pipe can generally have a substantially circular cross-section. Preferably, the heat pipe has a substantially rectangular cross-section, wherein in particular the corners of the rectangular cross-section can be rounded. This results in at least one substantially flat outer side for the heat pipe, which can easily be brought into surface thermal contact with the engine block. Preferably, a plurality of heat pipes are provided in order to be able to achieve a correspondingly high heat output. The heat pipe has a course that deviates from a straight line, in particular along its longitudinal extent, i.e. from a cooling region in which heat is absorbed to a heating region in which heat is released.The heat pipe can have an angled and / or curved path, in particular a multiple angled and / or curved path. This allows the heat pipe to be easily routed past other components of the motor vehicle, even in confined installation space, in order to extend from the engine block to the air duct of the air conditioning unit. The air duct of the air conditioning unit can be used, in particular, to draw in fresh air from the environment and / or to recirculate air from the passenger compartment. The air duct can have a heating device and / or a cooling device upstream and / or downstream of the part of the heat pipe arranged in the air duct in order to be able to set a specific temperature for the air in the air duct.

[0018] In particular, the engine block has a receiving channel, with the heat pipe being partially insertable into the receiving channel. The heat pipe can thus form a particularly large direct contact area with the engine block. In particular, the part inserted into the receiving channel can be in direct thermal contact with the engine block over the entire circumferential direction, possibly via a clearance fit.

[0019] Preferably, the heat pipe is displaceable between an inserted position and an at least partially, preferably completely, unplugged position relative to the engine block, in particular the receiving channel. The contact surface of the heat pipe with the engine block can be adjusted via the relative displaceability of the heat pipe to the engine block. In this case, the heat pipe can in particular also be positioned in an intermediate position between the inserted position and the unplugged position in order to be able to precisely adjust the heat flow flowing through the heat pipe. This also makes it possible to influence the heat flow from the engine block to the heat pipe. For example, during a cold start of the motor vehicle engine, the heat flow directed from the engine block to the heat pipe can be reduced or interrupted until a desired minimum temperature for the engine block, in particular a designated operating temperature, is reached.This prevents the vehicle engine from being cooled by the heat pipe during a period in which the vehicle engine should be warmed up. Furthermore, when a particularly high heating output is required from the air conditioning unit, an increased heat flow from the engine block to the heat pipe can be set, for example, to heat the passenger compartment to a desired target temperature after a cold start of the vehicle engine. In particular, several heat pipes are provided, which can be moved independently of one another between the plugged-in and unplugged positions. This allows the heat flow from the engine block to the air duct to be adjusted within a wide range.

[0020] Particularly preferably, the heat pipe has a cooling region for absorbing heat from the engine block in the plugged-in position, a heating region for heating the air in the air duct of the air conditioner in the plugged-in position, and an insulating region provided with thermal insulation arranged between the cooling region and the heating region. In the unplugged position, the insulating region is positioned within the air duct to at least partially prevent heat exchange with the air of the air duct. In particular, if heating of the air in the air duct of the air conditioner is not desired, for example because a target temperature for the passenger compartment has been reached or exceeded, the heat pipe can be moved to the unplugged position to prevent further heating of the air.Because the insulating area is relocated into the air duct and the heating area is moved out of the air duct in the unplugged position, residual heat from the heat pipe can no longer significantly heat the air. This prevents the air conditioner from having to increase its cooling capacity in order to counteract the heating of the air by the heat pipe. While the cooling area and / or the heating area can be designed for the greatest possible heat exchange capacity, the insulating area can be designed for the lowest possible heat exchange capacity with the help of the thermal insulation. In the plugged-in position, the insulating area can use the provided thermal insulation to prevent heat loss from the heat pipe to the environment, so that the greatest possible proportion of the heat flow given off from the engine block to the heat pipe can reach the air duct.

[0021] In particular, the heat pipe has a protruding stop, in particular a sealing element, for limiting the maximum insertion depth in the receiving channel. This prevents an axial end of the heat pipe from striking the engine block, thus reducing the risk of damage to the heat pipe. Furthermore, the stop can seal the receiving channel, preventing natural convection of residual air from the receiving channel in the event of a loose fit between the heat pipe and the receiving channel. This enables high heat exchange performance between the engine block and the heat pipe.

[0022] The heat pipe preferably has heating fins for providing a heat exchange surface within the air duct of the air conditioner. The heat pipe can be provided with the heating fins in a heating region of the heat pipe provided in the air duct. The heating fins can be attached to the outer surface of the heat pipe and extend in the circumferential direction or in the longitudinal direction of the heat pipe. In particular, a plurality of spaced-apart, in particular substantially parallel, heating fins are provided. The heating fins significantly increase the convective heat exchange performance between the heat pipe and the air in the air duct.

[0023] Particularly preferably, the heat pipe has a damping element to compensate for changes in the position of the engine block relative to the air duct of the air conditioning unit. Changes in the position of the motor vehicle engine caused by engine vibrations and / or thermal expansion can be automatically compensated by the damping element of the heat pipe. Jamming of the heat pipe between the engine block and the air conditioning unit, as well as component failure of the heat pipe, for example due to fatigue fracture, can thus be prevented.

[0024] In particular, the damper element has an elastically flexible curved region formed by the heat pipe. The damping element can thus be formed by the heat pipe itself if the heat pipe has a suitable shape. The curved region allows the already existing limited elasticity of the essentially metallic heat pipe to be used to compensate for possible changes in position. The end regions of the respective curved region can be elastically moved towards or away from one another in the event of a change in the bearing of the engine block, without the heat pipe being expected to break due to the position changes to be compensated for. Preferably, several curved regions are provided, each of which can compensate for a specific direction of a change in position.

[0025] Preferably, the heat pipe is designed as a heat pipe with a material transport of a condensed liquid working medium supported by capillary forces. The material transport of the working medium condensed in the heat pipe therefore does not need to be due to gravity, as is the case with a thermosiphon, so that a more complex geometric design of the heat pipe is possible and the relative position of the air conditioning unit to the engine block in the direction of gravity can be selected essentially arbitrarily. Instead, capillary tubes or similar devices provided in the heat pipe based on the wick principle can be used to achieve material transport of the liquid working medium supported and / or dominated by capillary forces, wherein in particular the material transport can also occur at least partially against the direction of gravity.

[0026] Particularly preferably, an exhaust air duct is provided that is communicable with the air duct of the air conditioning unit via a shut-off device for discharging the air tempered by the heat pipe past the passenger compartment to the surroundings. If heating of the passenger compartment by the air heated in the air duct with the aid of the heat pipe is not desired, this air can be discharged to the surroundings via the exhaust air duct. The air duct of the air conditioning unit can thus act as an air cooler for the motor vehicle engine, which in this case is not part of a front radiator cooled by airflow. With the aid of the shut-off device, the air from the air duct can be directed wholly or partially to the exhaust air duct and / or to the passenger compartment. In particular, the air flow from the air duct can be divided by the shut-off device in a desired ratio between the exhaust air duct and the passenger compartment, thereby facilitating regulation of the temperature in the passenger compartment.

[0027] The invention will be explained below by way of example with reference to the accompanying drawings using preferred embodiments, wherein the features presented below can represent an aspect of the invention both individually and in combination. They show: Fig. 1: a schematic diagram of an engine cooling system, Fig. 2: a schematic side view of a heat pipe for the engine cooling system from Fig. 1, Fig. 3 is a schematic sectional side view of another embodiment of the engine cooling system in a plugged-in position, Fig. 4: a schematic sectional side view of the engine cooling system in an unplugged position and Fig. 5: a schematic sectional view of a heat pipe of the engine cooling system from Fig. 3 and Fig. 4.

[0028] The Fig. The engine cooling system 10 shown in Figure 1 comprises an engine block 12 of a motor vehicle engine, to which several heat pipes 14 are directly thermally coupled. The heat pipes 14 extend into an air duct 16 of an air conditioning unit 18. The air duct 16 can draw in fresh air from the environment and direct it into a passenger compartment 20 of the motor vehicle. If the passenger compartment 20 is to be cooled, the air from the air duct 16 can be directed to the passenger compartment 20 via a cooling device 22, for example, having a condenser. If the passenger compartment 20 is to be heated, the air from the air duct can be heated by the heat pipes 14 and supplied to the passenger compartment 20, optionally via a further heating device. The air heated by the heat pipes 14 can be passed through a shut-off device 24, which can optionally divert the incoming air flow to an exhaust air line 26.The air heated by the heat pipes can be vented to the environment via the exhaust air duct 26, so that the heat pipes 14 only cool the engine block 12, but prevent undesirable heating of the passenger compartment 20. The cooling device 22 can also be coupled to the air duct 16 via another shut-off device 28. To regulate a specific temperature of the passenger compartment 20, the shut-off devices 24, 28, which may, for example, have an air flap and / or be configured as valves, can be suitably switched.

[0029] As in Fig. As shown in Figure 2, it is possible for the heat pipe 14 not to be straight, but rather to be provided with a curved section 30. The curved section 30 can, in particular, connect two substantially parallel sections of the heat pipe 14. The curved section 30 allows the parallel sections of the heat pipe 14 to be elastically moved toward and away from each other, thereby forming a damping element 32 that can automatically compensate for a change in position of the engine block 12 relative to the air conditioning unit 18 in the direction of the elastic compliance of the sections of the heat pipe 14.

[0030] As in Fig. 3, the engine block 12 can have a receiving channel 34 into which a cooling region 36 of the heat pipe 14 can be inserted in order to absorb the heat of the engine block 12. The insertion depth of the heat pipe 14 into the receiving channel 34 can be limited by a stop 38, which is designed in particular as an annular seal. The heat pipe 14 projects with a heating region 40 into the air duct 16 of the air conditioning unit 18 in order to release the heat absorbed in the cooling region 36 to the air in the air duct 16 in the heating region 40. An insulating region 42 can be provided between the cooling region 36 and the heating region 40, in which the heat pipe 14 is provided with thermal insulation 44. The thermal insulation 44 can prevent heat loss to the environment when the heat pipe 14 is in the inserted position. The damping element 32 can be provided between the cooling region 36 and the insulating region 42 and / or between the insulating region 42 and the heating region 40.

[0031] As in Fig. As shown in Figure 4, the heat pipe 14 can be displaced in the axial direction of the receiving channel 34 from the receiving channel 34 into the unplugged position. Heat transfer from the engine block 12 to the cooling region 38 can thereby be interrupted. At the same time, the axial displacement of the heat pipe 14 can move the heating region 40 of the heat pipe 14 out of the air duct 16 of the air conditioning unit 18, whereby, in particular, the insulating region 42 can be moved into the air duct 16. This can also interrupt heat transfer from the heat pipe 14 to the air of the air duct 16. The heat transfer functionality of the heat pipe 14 can thus be deactivated in the unplugged position.

[0032] As in Fig.As shown in Figure 5, the heat pipe 14 can be provided with heating fins 46 in the heating region 40 to increase the heat transfer performance between the heat pipe 14 and the air of the air duct 16 of the air conditioning unit 18. Preferably, the at least one heating fin 46 is hollow, so that the working medium of the heat pipe 14 can also reach the interior of the heating fin 46 and condense within the heating fin 46.

Claims

[1] Engine cooling system adapted for a motor vehicle engine of a motor vehicle, with a heat-generating engine block (12), a heat pipe (14) thermally coupled directly to the engine block (12) and designed to dissipate the heat and an air conditioning unit (18) arranged to control the temperature of a passenger compartment (20) of the motor vehicle, wherein the air conditioning unit (18) has an air duct (16) configured to supply air into the passenger compartment (20) and the heat pipe (14) projects into the air duct (16) to control the temperature of the air. [2] Engine cooling system according to claim 1 characterized by that the engine block (12) has a receiving channel (34), wherein the heat pipe (14) can be partially inserted into the receiving channel (34). [3] Engine cooling system according to claim 1 or 2 characterized bythat the heat pipe (14) is displaceable between an inserted position and an at least partially, preferably completely, unplugged position relative to the engine block (12), in particular the receiving channel (34). [4] Engine cooling system according to claim 3 characterized by in that the heat pipe (14) has a cooling region (36) for absorbing heat from the engine block (12) in the inserted position, a heating region (40) for heating the air in the air duct (16) of the air conditioning unit (18) in the inserted position and an insulating region (42) provided with thermal insulation (44) and arranged between the cooling region (36) and the heating region (40), wherein the insulating region (42) is positioned within the air duct (16) in the unplugged position to at least partially prevent heat exchange with the air of the air duct (16). [5] Engine cooling system according to one of claims 2 to 4 characterized bythat the heat pipe (14) has a protruding stop (38), in particular a sealing element, for limiting the maximum insertion depth in the receiving channel (34). [6] Engine cooling system according to one of claims 2 to 5 characterized by that the heat pipe (14) has heating fins (46) for providing a heat exchange surface within the air duct (16) of the air conditioning unit (18). [7] Engine cooling system according to one of claims 1 to 6 characterized by that the heat pipe (14) has a damping element (32) to compensate for changes in the position of the engine block (12) relative to the air duct (16) of the air conditioning unit (18). [8] Engine cooling system according to claim 7 characterized by that the damper element (32) has an elastically flexible curved region (30) formed by the heat pipe (14). [9] Engine cooling system according to one of claims 1 to 8 characterized bythat the heat pipe (14) is designed as a heat pipe with a material transport of a condensed liquid working medium supported by capillary forces. [10] Engine cooling system according to one of claims 1 to 9 characterized by that an exhaust air line (26) which can be communicated with the air duct (16) of the air conditioning unit (18) via a shut-off device (24) is provided for discharging the air tempered by the heat pipe (14) past the passenger compartment (20) to an environment.

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