Patent Application
20120006286
This application claims priority to German Patent Application No. 102010017766.0, filed on Jul. 6, 2010, the entire contents of which are being incorporated herein by reference.
The present disclosure relates to a cooling arrangement for an internal combustion engine, in particular for an internal combustion engine of a motor vehicle.
Cooling arrangements for internal combustion engines provide the intrinsic function of cooling, for example, an internal combustion engine and further components of a motor vehicle and, where appropriate, utilizing the heated coolant as a heat source for heating devices of, for example, an air conditioning system of the motor vehicle. It is likewise important for these cooling arrangements that air which is included in the cooling circuit of the cooling arrangement be regularly removed from the circuit.
Thus, in general, a balancing tank is provided in the cooling arrangement. This serves, inter alia, for separating air from the cooling circuit, for compensating the increase in volume of the coolant during heating, for filling the cooling arrangement with coolant, and for building up a pressure cushion in order to prevent the coolant from boiling. In order to vent the cooling circuit, it is possible to incorporate the balancing tank both into the internal engine circuit and into the overall cooling circuit normally routed via a thermostat.
In order to enable the coolant to flow out of the internal engine circuit to a cooler and therefore into the overall cooling circuit, a thermostat opens when the internal combustion engine or the coolant has reached a minimum desired operating temperature. The coolant stream is conventionally driven by a pump which is driven by the internal combustion engine via the crankshaft. The throughput of the pump consequently depends on the engine rotational speed.
To ensure proper venting of the cooling circuit when the pump output capacity is low, a minimum flow velocity of the coolant inside the venting lines has to be maintained. On the other hand, when the pump output capacity is high, a maximum flow velocity inside the venting lines should also not be overshot, so as to avoid foaming of the coolant and therefore an intermixing of the coolant with air or excessive lowering of the coolant level in the balancing tank.
These requirements are usually achieved by means of fixed through-flow cross sections in the venting lines, in conjunction with suitably configured balancing tanks, for example by means of deflection or baffle surfaces arranged in the tanks, by a specific shaping of the balancing tank, by the arrangement of the coolant inlet and coolant outlet ports on the balancing tank, and by the coolant volume.
Thus, a cooling arrangement for an internal combustion engine is described, for example, in GB 2 458 263 A. The coolant is pumped through the internal combustion engine by means of a circulating pump. Between the internal combustion engine and the cooler, a thermostatic valve is arranged, which opens when the coolant temperature in the internal combustion engine overshoots a predetermined temperature. Furthermore, the inlet side of a balancing tank is connected via a coolant inflow line to an upper end of the cooler, and the outlet side of the balancing tank is connected to the suction side of the pump via a coolant return line. In specific operating states, to prevent coolant from undesirably flowing back into the balancing tank via the coolant return line connected on the outlet side, a nonreturn valve is provided on the outlet side of the balancing tank. Furthermore, in another embodiment, a throughflow limiter in the form of a pressure-limiting valve is arranged in the coolant inflow line between the cooler and the balancing tank. So the pressure-limiting valve maintains a stipulated coolant operating pressure upstream of the limiting valve, to be precise, in the cylinder head of the internal combustion engine, for example, in the event of an abrupt decrease in pressure in the cooling circuit on account of a sudden change in engine rotational speed.
Furthermore, GB 2 458 264 A discloses a throughflow limiter for use in a cooling arrangement for an internal combustion engine. It is proposed, in particular, to use the through-flow limiter described in a coolant inflow line of a coolant balancing tank.
GB 2 437 064 A discloses a degassing tank for an engine cooling system. The degassing tank has a conical shape and has one or more smaller degassing chambers arranged in it. The inlet and outlet ports for the coolant are in each case arranged tangentially with respect to the degassing tank. This arrangement is intended to make it possible to carry out the degassing of the cooling system by means of a compact degassing tank in which, moreover, only a relatively small coolant quantity is stored.
On account of the nowadays preeminent requirements regarding the configuration of the engine space which generally receives the cooling arrangements of a motor vehicle, for example the provision of pedestrian protection measures, the accommodation of complex drive trains and low weight, the available construction space is greatly restricted. It is therefore especially desirable to reduce the volume of the coolant balancing tank to a minimum.
The inventors herein have recognized the above mentioned issues and have devised an approach to at least partially address them. In one embodiment, a cooling arrangement comprises a coolant balancing tank having an inlet side and an outlet side, the inlet side connected via a first venting line to an internal combustion engine and/or connected via a second venting line to a cooler, and the outlet side connected via a coolant return line to an inlet side of a pumping device. At least one of the first and second venting lines has a flow control unit for variably limiting a coolant volume flow.
In this way, a cooling arrangement for an internal combustion engine, in particular for an internal combustion engine of a motor vehicle, is provided, which has essentially a coolant balancing tank which is capable of being filled with a coolant and the inlet side of which is connected via a first venting line to an internal combustion engine and/or via a second venting line to a cooler for cooling the coolant, and the outlet side of which is connected via a coolant return line to the inlet side of a pumping device for pumping the coolant through the internal combustion engine. Furthermore, a flow control unit for variably limiting the coolant volume flow is provided in the venting line or venting lines. Preferably, each of the venting lines has a (variable) flow control unit.
Thus, satisfactory venting of the cooling circuit under all possible operating conditions is ensured, particularly also when the pump output capacity is very low. This allows the use of a substantially smaller-volume coolant balancing tank with a simple internal set-up. Since the volume flow of the coolant can be varied by means of the flow control unit during operation, the operating range in which satisfactory venting of the cooling circuit is possible can be extended in a simple way. If the extended operating range is not utilized, the cooling arrangement disclosed herein likewise makes it possible to use, instead, a substantially smaller coolant balancing tank having a simpler set-up. This requires a smaller construction space and saves weight, since the disclosed coolant balancing tank stores a smaller coolant quantity on account of the smaller volume. Moreover, as a result of the smaller coolant quantity in the cooling circuit, the optimal operating temperature of the internal combustion engine, particularly after a cold start, is reached substantially more quickly.
To ensure satisfactory venting of a cooling circuit, the permissible operating range of a cooling arrangement is determined essentially by the factors described below. The separation of the gaseous constituents included in the coolant from the cooling circuit depends generally on the flow velocity of the coolant in the cooling circuit. Thus, on the one hand, a minimum flow velocity of the coolant inside the venting lines is necessary in order to ensure satisfactory venting of the overall cooling circuit, but, on the other hand, too high a flow velocity leads to foaming of the coolant and therefore to increased mixing of air into the coolant and, moreover, to an excessive lowering of the coolant level in the balancing tank. Since the coolant pump which circulates the coolant in the cooling circuit is usually driven via the internal combustion engine or the crankshaft of the internal combustion engine, the flow velocity of the coolant in the case of predetermined fixed line cross sections in the cooling circuit depends directly on the output capacity of the coolant pump and therefore on the rotational speed of the engine. The permitted minimum or maximum flow velocity of the coolant and the output capacity of the coolant pump therefore determine the permissible operating range for satisfactory venting of the cooling circuit.
The variable limitation by the flow control unit, effected according to the embodiments disclosed herein, of the coolant volume flow in one or more venting lines allows the coolant flow in the venting line to be reduced or increased in a targeted manner during the operation of the cooling arrangement as a function of one or more operating parameters. Thus, according to one embodiment of the disclosure, the flow control unit is designed in such a way as to control the volume flow in the venting line as a function of an output capacity of the pumping device.
The cooling arrangement described above is shown schematically in
In the context of the present disclosure, venting is to be understood as meaning any separation of all gaseous constituents bound in the coolant from the coolant or from the cooling circuit. To simplify the following description, it may be pointed out that the following use of the term “venting line” in the singular is to be understood as not merely referring to a single venting line of the cooling arrangement, but also embraces further venting lines, insofar as these are provided in an embodiment of the cooling arrangement according to the disclosure, this being the case, for example, when the inlet side of the coolant balancing tank is connected via one venting line to the internal combustion engine and via a further venting line to the cooler.
The cooling arrangement 1 illustrated in
During a cold start of the internal combustion engine 2, that is to say before a minimum operating temperature of the coolant or of the internal combustion engine 2 is reached, the thermostat 9 is closed. This leads to a rapid heating of the coolant (shortening of the warm-up phase). After the minimum operating temperature of the internal combustion engine 2 or of the coolant is reached, the thermostat 9 opens and allows the coolant to circulate through the overall cooling circuit.
In the overall cooling circuit, in addition to the internal cooling circuit, the coolant flows through the cooler 7, which is connected on its inlet side via a third coolant line 17 to the outlet side 14 of the internal combustion engine 2, and subsequently back again to the thermostat 9 which is connected on its inlet side via a fourth coolant line 18 to the outlet side of the cooler 7. The cooler 7 serves for cooling the coolant in that the heat carried along by the coolant is discharged into the surroundings. In some embodiments, the cooler may be a radiator coupled to a fan 10, the fan controlled by an engine control unit, such as controller 27, to dissipate heat from the radiator to the surroundings while the vehicle is not in motion, for example.
As illustrated in
In the exemplary embodiment described in
The flow control units 19 and 21 may be controlled by a controller 27. While one controller 27 is shown in
The functioning of the flow control units 19 and 21 will be described in more detail with respect to
The functioning of the flow control unit 21 of the exemplary embodiment described is illustrated in a graph in
The line 24 illustrated by dashes in
The curve 26, which illustrates the flow velocity as a function of the pump output capacity in
The flow control unit 21 may be regulated to a stipulated desired value of the coolant volume flow either mechanically or electronically. For example, the controller 27 for the flow control unit 21 detects the actual value of the current volume flow as an input variable and feeds it to the flow control unit 21.
As can be seen in
As is also to be gathered from the curve 26, in the exemplary embodiment illustrated, the flow control unit 21 controls the volume flow of the venting line 6 continuously. That is to say, the flow control unit 21 continuously detects the output capacity of the pumping device 11 during the operation of the cooling arrangement 1 and controls the volume flow according to the value detected. The continuous control of the volume flow makes it possible to react as rapidly as possible to changed operating conditions and ensures that the cooling arrangement operates reliably.
The advantages of the cooling arrangement 1 become even clearer when compared with a conventional cooling arrangement which has no variable flow control unit.
In a preferred version, the cooling arrangement disclosed herein is used for the cooling of an internal combustion engine of a motor vehicle.
Turning to
The embodiments described herein may provide many advantages. Especially advantageously, the volume flow of the coolant in the venting line is raised when the output capacity of the pumping device is low, for example by increasing the effective line cross section of the venting line by means of the flow control unit. This ensures the minimum flow velocity for satisfactory venting of the cooling circuit even in the case of a low throughput of the pumping device, with the result that the permissible operating range of the cooling arrangement for satisfactory venting of the cooling circuit is extended downward. Furthermore, the venting of the cooling circuit afforded by the disclosed embodiments makes it possible especially advantageously, even in the case of a low output capacity of the pumping device, for example, to use an electric coolant pump which is operated in the low-load or part-load range for circulating the coolant in the cooling circuit. Thus, for example, the use of electric low-energy pumps may also be envisaged.
On the other hand, in the case of a high output capacity of the pumping device, the volume flow is advantageously reduced, for example by reducing the effective line cross section of the venting line by means of the flow control unit, in order to keep the flow velocity of the coolant substantially below the maximum permissible flow velocity. As a result, the permissible maximum flow velocity for satisfactory venting of the cooling circuit is not reached or is not overshot even in the case of a high throughput of the pumping device, and therefore the permissible operating range of the cooling arrangement for satisfactory venting of the cooling circuit is likewise extended upward.
In an especially advantageous refinement of the disclosed cooling arrangement, the flow control unit is designed for controlling the volume flow in the venting line, over the entire operating range of the cooling arrangement, substantially below the permissible minimum flow velocity. As a result, as compared with conventional cooling arrangements, the disclosed cooling arrangement makes it possible to use a substantially smaller-volume coolant balancing tank, with the result that the construction space required for the cooling arrangement and the coolant quantity stored in the balancing tank and therefore also the weight are reduced. Moreover, because of the smaller coolant quantity in the cooling circuit, the optimal operating temperature of the internal combustion engine, particularly after a cold start, is reached substantially more quickly.
Especially preferably, the flow control unit is designed in such a way as to keep the volume flow in the venting line virtually constant over the entire operating range of the cooling arrangement, for example by an appropriate adaptation of the effective line cross section of the venting line, so that a stipulated virtually constant optimal volume flow is achieved in the venting line as a function of the instantaneous separating state of the cooling arrangement. Optimal venting capacity of the cooling arrangement is thereby afforded. Furthermore, the use of a substantially smaller-volume coolant balancing tank is made possible, with the result that the construction space required for the cooling arrangement and the coolant quantity stored in the balancing tank and therefore also the weight are reduced. Moreover, because of the smaller coolant quantity in the cooling circuit, the optimal operating temperature of the internal combustion engine, particularly after a cold start, is reached substantially more quickly.
Furthermore, according to a further advantageous refinement, in addition to the output capacity of the pumping device, the flow control unit is designed for controlling the volume flow in the venting line as a function of the coolant temperature and/or of the coolant pressure. Thus, this refinement of the cooling arrangement according to the disclosure makes it possible not only to ensure satisfactory venting of the cooling circuit, but also to provide an optimal cooling capacity for the internal combustion engine. In the case of a raised coolant temperature, for example, the volume flow can be increased in order to allow for better degassing performance of the balancing tank. On the other hand, in the case of a low coolant temperature, the volume flow can be reduced, for example to zero, in order thereby to achieve a more rapid heating of the coolant and consequently a more rapid reaching of the optimal operating temperature of the internal combustion engine (shortening of the warm-up phase).
Especially preferably, the flow control unit is designed for carrying out the control of the volume flow continuously, that is to say, during the operation of the cooling arrangement, the flow control unit continuously detects one or more operating parameters and controls the volume flow, for example by varying the effective coolant line cross section, according to the detected parameter value, in such a way that the volume flow always assumes a value between the permissible minimum and maximum flow velocities, in order to ensure satisfactory venting of the cooling circuit in all operating states. The continuous control of the volume flow makes it possible to react as rapidly as possible to changed operating conditions and ensures that the cooling arrangement operates reliably.
In one embodiment disclosed herein, the flow control unit is arranged in the venting line. This offers the great advantage that the volume flow in each venting line can be controlled individually. Thus, for example, it is conceivable to prevent venting via the venting line arranged between the coolant balancing tank and the internal combustion engine, for example, temporarily and in the case of specific operating states of the internal combustion engine, which may be especially advantageous during a cold start, in order to achieve as rapid a heating of the coolant as possible in the internal cooling circuit and consequently a rapid reaching of the optimal operating temperature of the internal combustion engine. The individual control of the volume flows in the respective venting lines likewise makes it possible to have a venting and a cooling capacity adapted optimally to the local operating states of the components connected to the coolant balancing tank via the venting lines.
In another embodiment, the flow control unit may be arranged at an inlet port of the venting line into the coolant balancing tank. If a plurality of venting lines are connected on the inlet side to the coolant balancing tank, it is especially preferable to connect these to the balancing tank via one common inlet device, for example one common inlet connection piece, so that a single flow control unit is advantageously provided on the coolant balancing tank, in order to control the volume flow for all the connected venting lines simultaneously. Thus, an especially compact cooling arrangement is provided, which nevertheless affords the already-mentioned advantages with regard to optimal venting and cooling capacity. A flow control unit which controls the respective volume flow may, of course, also be provided in each case at each inlet connection piece, both flow control units also being switchable by control technology such that mutually coordinated volume control can be achieved.
Note that the example control and estimation routines included herein can be used with various engine and/or vehicle system configurations. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various acts, operations, or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated acts or functions may be repeatedly performed depending on the particular strategy being used. Further, the described acts may graphically represent code to be programmed into the computer readable storage medium in the engine control system.
It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, because numerous variations are possible. For example, the above technology can be applied to V-6, 1-4, 1-6, V-12, opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein.
The following claims particularly point out certain combinations and sub-combinations regarded as novel and non-obvious. These claims may refer to “an” element or “a first” element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102010017766.0 | Jul 2010 | DE | national |
