EP2345803A1 - Coolant circuit of a combustion engine and a work method for operating same - Google Patents

Abstract

The circuit has a bypass element (5) arranged in flow direction of coolant behind an internal-combustion engine (1) for supply of partial flow of the coolant to supply pipes (7, 14) that is connected with the engine by a switching valve. The switching valve is assigned a heat accumulator circuit or a collecting pipe (13) by a junction that connects a heat exchanger (12) and a heat accumulator. The collecting pipe is connected with a return pipe by another junction (9) before an inlet of a main coolant pump (2), where the return pipe is connected with a main radiator (6). An independent claim is also included for a method for operating a cooling circuit of an internal-combustion engine.

Description

Cooling circuit of an internal combustion engine and a working method for operating a cooling circuit

The invention relates to a cooling circuit of an internal combustion engine, with a main radiator and a main coolant pump in a main coolant circuit and a heat accumulator, a switching valve, a check valve and another, a heat storage circuit of the heat accumulator associated coolant pump in the secondary coolant circuit. Furthermore, the invention relates to a working method for operating such a cooling circuit.

Conventional internal combustion engines for vehicles generally have a cooling circuit, wherein the coolant cools quickly after switching off the internal combustion engine, so that the cold start of the internal combustion engine after a longer life, the working fluid having relatively low temperatures, which are substantially below the operating temperature. Especially at low ambient temperatures at which cool the working fluid accordingly strong, problems arise for the start and operation of the internal combustion engine.

Among other disadvantages, in particular, a substantial increase in the fuel consumption of the internal combustion engine by increased friction in the internal combustion engine and by a deteriorated mixture formation. The greater friction results from the fact that at the lubrication points, the lubricant has an increased toughness due to the low temperatures. Also, the deteriorated mixture formation results from the adverse temperature conditions in which the fuel supplied to the air is difficult to vaporize.

For the faster warming up of the internal combustion engine after the cold start, it is possible to integrate a heat storage in the cooling circuit. For the optimal use of such a heat storage, it is desirable to include it in the circuit so that it can be used in different ways.

The DE 195 12 821 A1 relates to a method for operating heat storage for the heating of the internal combustion engine during cold start. This starts the engine start the circulation of the heat carrier through the memory until the entire contents of the heat accumulator is replaced, at the latest when switching off the ignition of the engine, the circulation is reused and maintained across the store until the contents of the heat store are completely replaced.

The DE 44 02 215 A1 relates to a method for improving the cold start behavior of internal combustion engines by coupling heat energy. In the cooling circuit of a vehicle, a latent heat accumulator is connected in series with the heater core. During operation of the internal combustion engine, the heated cooling water flows through the latent heat accumulator, so that thermal energy is stored according to the dimensioning in the latent heat storage when switching off the internal combustion engine. On the next cold start, the heat is released with a short-term power, which allows the engine to be heated up within a few seconds to reduce emissions of pollutants already in the start-up phase. In addition, the heating system of the vehicle is brought to operating temperature faster.

Of the DE 33 41 097 A1 the object is to provide an internal combustion engine that allows a more favorable operation with reduced fuel consumption even for those vehicles that are operated only relatively short time and with larger distances between the individual operating times. For this purpose, a substantial part of the working fluid is stored after switching off the internal combustion engine in a provided with heat-insulating walls reservoir and supplied to the working fluid circuit when restarting the internal combustion engine.

Also according to the DE 32 15 342 A1 a large part of the existing when switching off the engine in the coolant and engine oil circuit heat is stored by means of thermos and heat insulation by utilizing the existing volumes and is preheated available when restarting.

The DE 41 04 093 A1 refers to a cooling system for vehicles with internal combustion engine, in which depending on a plurality of measured state variables, in particular the operating temperatures, an individual power control of each cooling circuit is possible. By speed-controlled pumps or an electrically controllable valve, the respective throughput of the heat exchange fluid can be controlled by the heat exchanger. The suppression of the cooling in the warm-up phase can be achieved by inhibiting the fluid flow rate by switching off the pump or closing the valves in the relevant line.

These different circuits for using the heat accumulator are, for example, by the use of multiple valves or a central valve, which has a larger number of Switch positions enabled, feasible. The use of multiple valves, however, leads to high system costs and also requires additional space.

Against this background, the invention has the object to realize different circuits involving the heat storage, which should be dispensed with expensive valves. In particular, a central multi-way valve for a variety of different switching states should be omitted. Furthermore, a working method for operating such a cooling circuit to be created.

The first object is achieved with a cooling circuit according to the features of claim 1. The dependent claims relate to particularly expedient developments of the invention.

According to the invention, therefore, a cooling circuit of an internal combustion engine is provided, in which a branching element for supplying at least a partial flow of the coolant to a supply line is arranged in the flow direction of the coolant behind the internal combustion engine through which the coolant by means of the same or another branching element a heating heat exchanger and / or Heat storage is fed, wherein the coolant by means of a heat storage circuit associated switching valve optionally supplied to the internal combustion engine supply line or by means of a heating heat exchanger and the heat storage node of a connecting example comprising a check valve manifold is fed by means of a node in the flow direction in front of an inlet of the main coolant pump is connected to a connected to the main cooler return line. As a result, in a surprisingly simple manner, the different operating conditions in addition to the normal operation of the internal combustion engine, namely the supply of the heating heat exchanger for heating the interior of the motor vehicle, the preheating of the engine from the contents of the heat accumulator and the supply of the heat accumulator with the required thermal energy during the Operation of the internal combustion engine already by a single switching valve in conjunction with at least one check valve and an electric coolant pump feasible.

In addition to the usual operation so various other circuits can be realized with the involvement of the heat accumulator, for example, to supply the same with the desired thermal energy through a corresponding circuit position of the switching valve with the support of the coolant pump. Furthermore, a circuit for supplying the interior heating in the same switching position of the switching valve by turning off the main coolant pump and in the other switching position of the switching valve is adjustable at likewise switched off main coolant pump by means of the supply line a preheating circuit for heating the internal combustion engine before the startup of the internal combustion engine, so as to achieve a shortening of the warm-up phase. These at least three further circuits can be realized without expensive multiway valves, the effect of the invention is based primarily on the efficient use of the heat accumulator associated switching valve in conjunction with the combination of switching on and off the electrically driven coolant pump and / or the main coolant pump.

In this case, the main coolant circuit comprises at least the internal combustion engine, the main coolant pump and the main radiator and the heat storage circuit at least the heat accumulator, the coolant pump, the switching valve and the heating heat exchanger.

A particularly advantageous embodiment of the present invention is achieved in that an outlet of the internal combustion engine is connected to a bypass line through which at least a partial flow of the coolant, bypassing the main radiator by means of another, in particular controlled by a thermostat switching valve of the return line can be fed. This makes it possible, for example in the warm-up phase, to bypass the main water cooler and to pass the coolant exiting the internal combustion engine through the bypass line back to the main coolant pump and back to the inlet of the internal combustion engine. For this purpose, the bypass line can be connected directly to the outlet of the internal combustion engine or to the supply line.

In this case, it proves to be particularly practical if a check valve is arranged in the bypass line, so that a backflow of the from the manifold through the node in the supply, especially in an additional operation of the coolant pump, is excluded.

A further, likewise particularly expedient embodiment of the invention is also achieved in that the cooling circuit has an engine oil cooler which is connected to the outlet of the internal combustion engine and whose outlet is connected to the collecting line. In this case, the coolant emerging from the internal combustion engine is used for heat exchange with the engine oil. The proportion of the motor oil cooler on the one hand and the heating heat exchanger on the other hand can be supplied coolant flow is adjustable according to the respective operating circumstances or in response to detected signals by means of a control unit.

In principle, it is conceivable to provide a flow through the oil cooler and the heating heat exchanger in succession so as to use the optionally introduced by the hot oil in the coolant additional thermal energy in the heating heat exchanger for heating the passenger compartment. It is particularly useful, however, when the engine oil cooler is arranged in a parallel arrangement to the heating heat exchanger between the supply line and the manifold, for example, an independent admission to the coolant and the flow through the engine oil cooler or the heating heat exchanger can be interrupted if necessary.

To avoid unwanted return from the manifold in the engine oil cooler a simple, particularly practical modification is realized in that downstream of the engine oil cooler a check valve is arranged in the flow direction, which is preferably positioned in the immediate vicinity of an outlet of the engine oil cooler or integrated into this.

The coolant pump can basically be arranged in any position in the heat storage circuit. Particularly effective is an arrangement of the further coolant pump in the flow direction in front of the heat accumulator so as to be able to provide a constant volume flow as needed.

The supply line essentially or exclusively serves to supply the internal combustion engine before or during the cold start phase with preheated coolant from the heat accumulator, which can be directly connected to an inlet of the internal combustion engine by means of the supply line. On the other hand, it is particularly expedient if the supply line is connected to a further node with an inlet of the internal combustion engine and an outlet of the main coolant pump, so that the manifold and the supply line lead to a common inlet of the internal combustion engine.

Furthermore, an embodiment of the invention proves to be particularly successful, in which a check valve is arranged in the supply line. Thereby, in the normal operating phase, in which the switching valve connects the heat accumulator to the supply line so as to interrupt the circulation of the coolant from the supply line back to the manifold and to prevent the further filling of the heat accumulator, the supply of emerging from the main coolant pump coolant avoided in the supply line. An additional obturator is unnecessary.

The further object of the invention to provide a working method for operating a cooling circuit of an internal combustion engine is inventively achieved in that in addition to a first circuit in which the coolant flows through the internal combustion engine, the main radiator and the main coolant pump in succession, at least a second circuit in which in addition to the first circuit, a heat storage and a coolant pump are flowed through successively, a third cycle in which the coolant flows through the heat storage by means of the coolant pump via a switching valve in the first switching position the heating heat exchanger with the main coolant pump is switched off, or a fourth cycle in which the Coolant from the heat storage means of the coolant pump via a switching valve in the second switching position, the supply line, the internal combustion engine and the return line with switched off main coolant pump na flows through each other, can be adjusted.

In a particularly simple manner, the various circuits are achieved solely by switching on and off of the main coolant pump on the one hand and the coolant pump on the other hand in conjunction with a switching valve for supplying the coolant from the heat storage alternative to the supply line or the manifold. While the coolant pump is switched off in the normal operation of the internal combustion engine and the heat storage circuit is interrupted by the switching position of the switching valve, the connection of the coolant pump in connection with the commissioning of the main coolant pump in the other, the heat storage circuit closing position of the switching valve leads to a desired flow through the heat accumulator, which is supplied in this way with the desired thermal energy. Due to the switching position of the switching valve, two alternative circuits are determined when the main coolant pump is switched off. On the one hand, the cycle is limited solely to the coolant pump, the heat accumulator and the heating heat exchanger, with the result of heating the passenger compartment. In the alternative switching position, the coolant does not reach the heating heat exchanger, but through the supply line to the internal combustion engine and by means of the supply line through the coolant pump back into the heat storage. As a result, therefore, a desired preheating of the internal combustion engine can be carried out even when the main coolant pump is at a standstill.

Die Erfindung lässt zahlreiche Ausführungsformen zu. Zur weiteren Verdeutlichung ihres Grundprinzips ist eine davon in der Zeichnung dargestellt und wird nachfolgend beschrieben. Diese zeigt jeweils in einer Prinzipdarstellung der Erfindung in

Fig. 1

einen gewöhnlichen Betrieb der Brennkraftmaschine als einen ersten Kreislauf des Kühlmittels;

Fig. 2

einen Füllbetrieb des Wärmespeichers als einen zweiten Kreislauf.des Kühlmittels;

Fig. 3

einen Heizbetrieb als einen dritten Kreislauf des Kühlmittels;

Fig. 4

einen Vorwärmbetrieb der Brennkraftmaschine als einen vierten Kreislauf des Kühlmittels.

For a better overview of the possible coolant flows, the different circuits are shown below with reference to a diagram for different coolant flows with the coolant pump switched on, while the shutdown of the coolant pump, which is not carried out further, leads to a normal operation of the internal combustion engine known per se.

The invention allows numerous embodiments. To further clarify its basic principle, one of them is shown in the drawing and will be described below. This shows in each case in a schematic diagram of the invention in

Fig. 1

a normal operation of the internal combustion engine as a first circuit of the coolant;

Fig. 2

a filling operation of the heat accumulator as a second cycle of the coolant;

Fig. 3

a heating operation as a third cycle of the coolant;

Fig. 4

a preheating operation of the internal combustion engine as a fourth circuit of the coolant.

FIG. 1 shows a cooling circuit of an internal combustion engine 1 of a motor vehicle, not shown, which can be adapted by simple means to different operating conditions. For this purpose, the coolant enters the in FIG. 1 shown normal operation of Internal combustion engine 1 due to the pump pressure generated by the main coolant pump 2 first to an inlet 3 of the internal combustion engine 1. The thereby heated coolant flows through an outlet 4 of the internal combustion engine to a branching element 5, so that a partial flow of the coolant into a main cooler 6 of a main coolant circuit and another, uncooled partial flow of the coolant enters a supply line 7 of a secondary coolant circuit. In the main coolant circuit, the coolant cooled by the main radiator 6 is delivered to a thermostatic valve 8. In the course of this coolant flow from the main coolant circuit is combined by means of a node 9 with the second coolant flow of the secondary coolant circuit, so that the entire coolant is then returned to the main coolant pump 2. In the main coolant circuit, a by-pass valve 10 equipped with a check valve 10 allows the bypassing of the main cooler 6 in response to the switching position of the thermostatic valve 8, so as to allow a faster heating of the coolant in a cold start phase. In the secondary coolant circuit, the coolant is supplied by means of the supply line 7 to a heating heat exchanger 12, which serves as needed heating a passenger compartment of the motor vehicle, not shown. The coolant cooled in this way then passes into a manifold 13 and back to the main coolant pump 2 via node 9. A further supply line 14 connects the outlet 4 of the internal combustion engine 1 with a motor oil cooler 15 whose outlet is connected to the manifold 13 by means of a check valve 16 is. In this case, arranged in the manifold 13 further check valve 17 prevents the undesirable backflow of the coolant to the heating heat exchanger 12th

In FIG. 2 a circuit of the coolant is shown, which corresponds to a filling operation of a heat storage 18. In order to supply the heat accumulator 18 with the required thermal energy, only a switching valve 19 is brought into a heat storage circuit enabling position, while both the main coolant pump 2 and a further coolant pump 20 are in operation. As a result, the coolant passes not only in the manner described above to the heating heat exchanger 12, but also via a branching element 21 in the supply line 7 and to the heat storage 18, which is connected in parallel to the heating heat exchanger 12. In this case, an undesirable backflow of the coolant from the heating heat exchanger 12 is prevented via a node 22 back into the heat accumulator 18, so that here a check valve is unnecessary. At the same time can be adjusted by the control of the coolant pump 20 of the heat storage 18 each to be supplied flow.

In contrast, in FIG. 3 only the coolant pump 20 in operation, so that the coolant is circulated exclusively within the heat storage circuit. In particular, arrives Thus, the tempered coolant from the heat storage 18 by a corresponding switching position of the switching valve 19 via the node 22 to the heating heat exchanger 12 and from there via the coolant pump 20 back into the heat accumulator 18. Accordingly, the coolant in this circuit is only the provision of thermal energy for heating of the passenger compartment of the motor vehicle. The coolant does not flow through the manifold 13, because the return flow into the engine oil cooler 15 are excluded by the check valve 16 as well as in the bypass line 11 through the check valve 10. The further conduction path to the inlet 3 of the internal combustion engine 1 is also blocked by the stoppage of the main coolant pump 2, so that the coolant circuit can be limited to the heat storage circuit without additional shut-off devices.

Finally, in the FIG. 4 nor a Vorwärmbetrieb the internal combustion engine 1 shown as a fourth cycle of the coolant, which starting from the in FIG. 3 shown heat storage circuit by a change in the switching position of the switching valve 19 is adjustable. As a result, the coolant passes from the heat accumulator 18 to a check valve 24 having supply line 23 and on to the inlet 25 of the internal combustion engine 1. The return flow into the also connected to the engine 1 main coolant pump 2 is excluded at standstill by a shut-off element, not shown. Therefore, the tempered coolant flows through the internal combustion engine 1 and passes through the branching element 5 and through the supply line 7 to the coolant pump 20 and back to the heat accumulator 18. In this case, an undesirable flow through the main cooler 6 is prevented solely due to the pressure conditions.

Claims (9)

Cooling circuit of an internal combustion engine (1), comprising a main cooler (6) and a main coolant pump (2) in a main coolant circuit and a heat accumulator (18), a switching valve (19), a check valve (10, 16, 17, 24) and another, a branching element (5) for the supply of at least a partial flow of the coolant to a supply line (7, 14) is arranged downstream of the internal combustion engine (1) in the flow direction of the coolant, a heat storage circuit by which the coolant by means of the same or a further branching element (21) to a heating heat exchanger (12) and / or the heat accumulator (18) can be fed, wherein the coolant by means of the heat storage circuit associated switching valve (19) optionally one with the internal combustion engine (1) Supply line (23) or by means of a heating heat exchanger (12) u Node (22) connecting to the heat accumulator (18) can be fed to a collecting line (13) which in particular has a check valve (17) and which is connected upstream of an inlet of the main coolant pump (2) by means of a node (9) upstream of an inlet of the main coolant pump (6) ) connected return line is connected. Cooling circuit according to claim 1, characterized in that an outlet (4) of the internal combustion engine (1) with a bypass line (11) through which at least a partial flow of the coolant, bypassing the main radiator (6) by means of a further switching valve, in particular a thermostatic valve (8), the main coolant pump (2) can be fed. Cooling circuit according to claim 2, characterized in that in the bypass line (11) a check valve (10) is arranged. Cooling circuit according to at least one of the preceding claims, characterized in that the cooling circuit has a with the outlet (4) of the internal combustion engine (1) connected to the engine oil cooler (15) whose outlet is connected to the manifold (13). Cooling circuit according to claim 4, characterized in that the engine oil cooler (15) in a parallel arrangement to the heating heat exchanger (12) between the supply line (7) and the manifold (13) is arranged. Cooling circuit according to claim 4 or 5, characterized in that in the flow direction behind the engine oil cooler (15) a check valve (16) is arranged. Cooling circuit according to at least one of the preceding claims, characterized in that the further coolant pump (20) in the flow direction in front of the heat accumulator (18) is arranged. Cooling circuit according to at least one of the preceding claims, characterized in that the supply line (23) has a check valve (24). Working method for operating a cooling circuit of an internal combustion engine (1) according to at least one of the preceding claims, wherein optionally a first circuit in which the coolant flows through the internal combustion engine (1), the main cooler (6) and the main coolant pump (2), or at least one of the following cycles is set: ■ a second circuit in which, in addition to the first circuit, a heat accumulator (18) and a coolant pump (20) are flowed through in succession, ■ A third circuit in which the coolant from the heat accumulator (18) by means of the coolant pump (20) with the main coolant pump (2) in the first switching position of a switching valve 19) flows through the heating heat exchanger (12), and / or ■ a fourth cycle in which the coolant from the heat accumulator (18) by means of the coolant pump (20) with the main coolant pump (2) switched off in the second switching position of the same or another switching valve (19) the supply line (23), the internal combustion engine (1) and the return line (7) flows through.

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