DE102010001752A1 - Cooling system for use in internal combustion engine of hybrid vehicle, has exhaust gas recirculation radiator connected with low temperature refrigerant circuit according to termination of warming-up phase - Google Patents

Abstract

The system (1) has high-and low temperature refrigerant circuits (3, 4) including high-and low temperature radiators (8, 23). An exhaust gas recirculation radiator (29) stays in connection with the low temperature refrigerant circuit, and is disconnected from the high temperature refrigerant circuit. Controlling elements (14, 16) connect the radiator with the high temperature refrigerant circuit during warming-up phase and/or according to the warming-up phase such that the radiator is connected with the low temperature refrigerant circuit according to termination of the warming-up phase.

Description

The invention relates to a cooling system of an internal combustion engine having a high-temperature coolant circuit with a high-temperature radiator and a low-temperature coolant circuit with a low-temperature radiator, the internal combustion engine comprising an EGR cooler, which communicates with the low-temperature coolant circuit, which is separated from the high-temperature coolant circuit.

The AT 001 620 U1 discloses an internal combustion engine with liquid cooling. A liquid cooler cools cooling liquid, wherein an integrated exhaust gas cooler is provided for cooling recirculated exhaust gas. To shorten the warm-up phase suggests the AT 001 620 U1 in addition to the exhaust gas cooler to arrange an oil cooler downstream of the exhaust gas cooler.

From the DE 101 43 091 A1 A method and apparatus for utilizing exhaust gas recirculation for cabin heating of motor vehicles is known. By means of temperature measurement, the demand for heat to be obtained from the EGR cooler for the coolant is determined and the exhaust gas enthalpy flow required for this purpose is set by the EGR cooler by means of the engine control. Due to the design of the heat exchanger and a lower coolant volume flow, the coolant at the heating heat exchanger experiences at least a temperature reduction of at least 30K.

Also the DE 196 33 190 A1 discloses an exhaust gas recirculation line in which a cooling device is arranged. The cooling device is connected via a branch line and a return line with lines of the engine cooling circuit. The exhaust gas recirculation line opens into the fresh air line of the internal combustion engine after passing through the EGR cooler.

The EP 1 055 813 A2 (= DE 199 24 398 A1 ) discloses that the exhaust heat exchanger controlled to use exhaust heat is operable, wherein in the exhaust gas recirculation line downstream of the EGR valve, a first switch for connection to a machine exhaust line and in an inlet and outlet line of the EGR heat exchanger in one of the throttle thermostats immediate bypass -Leitung a second switch to the coolant circulation are provided, wherein the EGR valve and the two switches are map-controlled in exhaust heat recovery in the coolant circulation.

The DE 600 29 874 is concerned with a coolant circulating device in a hybrid vehicle.

The DE 699 12 173 T2 discloses that an amount of recirculated exhaust gas is increased or decreased in accordance with an introduction amount of the fuel gas.

Likewise, the DE 10 2005 042 396 A1 an existing exhaust cooler to the main radiator recirculated exhaust gas. Both cooling units are spatially separated, wherein the air flow for the exhaust gas cooler and the air flow for the main radiator are spatially separated from each other from the environment.

The summary of JP 20052113761 It is apparent that a closing or opening valve is disposed in the coolant circuit which inhibits or reduces coolant flow therein, with coolant flowing in the EGR cooling circuit when an actual temperature has reached or is lower than a predetermined temperature.

In the summary of KR 1020020043726 A It is disclosed that by means of the heat recovery from recirculated exhaust gas, the cabin heating and an improved warm-up phase are ensured.

The DE 600 24 390 T2 (= US 6,244,256 B1 ) also discloses an internal combustion engine with exhaust gas recirculation system. However, two exhaust gas coolers are provided so that their dimensions taken together are smaller than a single exhaust gas cooler, which saves space.

The DE 603 04 875 T2 (= WO2004 / 22940 ) discloses an engine cooling system. A temperature detecting means detects the temperature of the coolant from the radiator return line at a second inlet and the temperature of the coolant from a motor return line at a first inlet.

The originating from the applicant DE 10 2008 036 277 A1 discloses a cooling system with insulated cooling circuits, with a high-temperature cooling circuit and a low-temperature cooling circuit. In both cooling circuits circulates a coolant. The coolant flows do not mix. Both cooling circuits each have an EGR cooler, on the one hand for high temperatures and on the other for low temperatures.

The DE 10 2005 055 323 A1 discloses a cooling device with an inlet-side and an outlet-side collection box, between which a cooling area is arranged, which is subdivided into a main cooling area and a low-temperature area. In the inlet-side header box, a valve is arranged, which opens or closes the low-temperature range to the main area depending on operating parameters.

In the EP 1 772 612 A1 an EGR cooling system is disclosed. The EGR cooling system is separated from the engine cooling system. By means of a bypass, the EGR cooler may be bypassed, with a flow valve adjusting the amount of refrigerant flowing through the bypass based on a temperature in a cooling path.

The WO 2005/073535 discloses an arrangement for cooling recirculated exhaust gas and charge air in a motor vehicle with a turbocharger having at least one respective heat exchanger for the exhaust gas flow and a heat exchanger for the charge air flow. At least one heat exchanger for the exhaust gas flow and one heat exchanger for the charge air flow are part of a common low-temperature coolant circuit. The exhaust gas cooler is designed in two stages. A first stage of the EGR cooler is incorporated in the main cooling circuit parallel to the engine and serves to transfer heat from the exhaust gas to be recirculated to the coolant in the main cooling circuit. A second stage of the two-stage exhaust gas recirculation cooling is integrated into the low-temperature cooling circuit parallel to the charge air cooler and serves to transfer heat from the exhaust gas to be recirculated to the coolant in the low-temperature cooling circuit.

In order to improve the cooling efficiency of an EGR cooler is therefore known, in addition to the actual engine cooling circuit, which can also be referred to as a high-temperature cooling circuit to provide a separate cooling circuit as a low-temperature cooling circuit. This low-temperature circuit is completely separated from the engine cooling circuit, wherein a low-temperature radiator is integrated in the low-temperature circuit. The EGR cooler is in contact with or connected to the low-temperature cooling circuit. Since the low-temperature cooling circuit is completely separated from the engine cooling circuit, it follows inevitably that the heat absorbed by the EGR cooler heat is transferred only in the low-temperature cooling circuit. However, this is disadvantageous in particular in the warm-up phase of the internal combustion engine, since the heat absorbed by the recirculated exhaust gas is not transferred into the engine cooling circuit.

In this respect, the invention has for its object to improve a cooling system of the type mentioned by simple means so that the warm-up phase of the engine is favorably influenced, so is shortened.

According to the invention the object is achieved by a cooling system with the features of claim 1, wherein the control system connects the EGR cooler in a warm-up phase with the high-temperature coolant circuit, and closes the connection to the high-temperature coolant circuit after completion of the warm-up phase, so that the EGR cooler after completion of the Warm-up phase is again connected to the low-temperature coolant circuit.

Advantageously, it is thus achieved that the EGR cooler or the EGR cooling circuit is connected to the high-temperature coolant circuit only for a limited period of time so as to transfer the heat absorbed by the recirculated exhaust gas to it only in the warm-up phase. As a result, the coolant in the high-temperature circuit, ie in the engine cooling circuit, is warmed up more quickly by the additional heat input, thus improving the heat recovery. Once the warm-up phase has ended, the EGR cooler or the EGR coolant circuit is reconnected to the low-temperature cooling circuit and disconnected from the high-temperature coolant circuit.

Favorable in the context of the invention is when the control system between the high-temperature coolant circuit and the low-temperature coolant circuit is arranged, wherein the EGR coolant circuit and the only EGR cooler is connected to the control system. In a first embodiment, the control system is designed such that it has a low-temperature input, a low-temperature output, a high-temperature input, a high-temperature output, an EGR cooler output and an EGR cooler input, it being impossible to mix the two cooling circuits due to the configuration of the control system.

In a preferred embodiment, it is provided for the first embodiment that the control system is designed as a 4-way valve. This can be switched depending on the operating parameter, so that the coolant of the EGR cooling circuit can flow either into the high-temperature outlet or into the low-temperature outlet. During the warm-up phase, the coolant of the EGR cooling circuit can not mix with the coolant of the high-temperature circuit.

When the warm-up phase is over, the path of the EGR coolant to the high-temperature circuit is closed and the path to the low-temperature circuit is opened. A mixing of the two coolant circuits is not possible in this case.

However, coolant may continue to circulate in the low-temperature cycle during the warm-up phase without fear of mixing the coolants from the low-temperature cooling circuit and the high-temperature circuit. It is essential, however, that the heat of the EGR coolant during the warm-up phase on the Coolant of the high-temperature cooling circuit is transmitted.

The control system is expediently connected to a preferably central control unit of the internal combustion engine or of the motor vehicle, wherein the corresponding operating parameters for determining a warm-up phase or its termination are stored in the control unit. The operating parameters are recorded in a conventional manner with appropriate devices and transmitted to the control unit. By way of example, a temperature amount of the coolant z. B. be included in the engine cooling circuit. If this reaches the predetermined and previously defined limit temperature, which detects a warm-up phase or its end, the control unit generates a corresponding control signal for the corresponding switching of the exemplary 4-way valve.

In a further embodiment of the invention, it is provided that the control system is formed of a plurality of control valves, preferably two control valves, one of which is associated with the low-temperature cooling circuit as a low-temperature valve and the other as a high-temperature valve the high-temperature cooling circuit.

In this advantageous embodiment may be provided between the two control valves, a connecting line, in which the EGR cooler is arranged.

During the warm-up phase, the low-temperature valve (corresponding signal from the control unit) is closed and the high-temperature valve is opened. During the warm-up phase, the coolant of the high-temperature cooling circuit can thus flow via the connecting line through the single EGR cooler and back into the high-temperature circuit. When the warm-up phase is over, the high-temperature valve is closed and the low-temperature valve is opened, so that the low-temperature cooling circuit is reconnected to the EGR cooler.

In the flow direction of the coolant behind the EGR cooler branches off from the connecting line outlets to both the low-temperature cooling circuit and the high-temperature circuit. In this respect, a slight mixing of the coolant streams downstream of the single EGR cooler take place.

Further advantageous embodiments are disclosed in the subclaims and the following sequence description. Show it:

1 a cooling system of an internal combustion engine of a motor vehicle in a first embodiment as a schematic diagram, and

2 a cooling system of an internal combustion engine of a motor vehicle in a second embodiment as a schematic diagram.

In the different figures, the same parts are always provided with the same reference numerals, so that these are usually described only once.

1 shows a cooling system 1 an internal combustion engine 2 a motor vehicle. The cooling system 1 has a high temperature cooling circuit 3 and a low temperature cooling circuit 4 on.

The high temperature circuit 3 has the output side of the internal combustion engine 2 a thermostat 6 on, from which a radiator connection line 7 to a high temperature cooler 8th branches. The coolant flows out of the internal combustion engine 2 through the thermostat 6 over the radiator connection line 7 through the high temperature cooler 8th , From this emerges the coolant, and is via a pump connection line 9 an input side of the internal combustion engine 2 arranged water pump 11 supplied, so that the internal combustion engine 2 cooled coolant is supplied.

From the thermostat 6 still branches a second connection line 12 which is in the pump connection line 9 empties. The thermostat 6 (Expansion element or wax thermostat) is designed so that this is the radiator connection line 7 opens when the coolant has a temperature amount above a predetermined temperature. The connection line 12 is directly connected to the cooling circuit of the engine and is not regulated by the thermostat.

From the connection line 12 branches a high temperature input line 13 which is in a control system 14 , which in this case as a 4-way valve 16 executed, flows. The confluence provides a high temperature input 17 dar. From the 4-way valve 16 is a high temperature exit pipe 18 into the pump line 9 led out. The output of the high temperature output line 18 from the 4-way valve 16 makes a high temperature output 19 represents.

At the 4-way valve 16 is the low-temperature cooling circuit 4 connected, which via one of the 4-way valve 16 outgoing low temperature line 22 with a low temperature cooler 23 communicates. The output of the low temperature line 22 from the 4-way valve 16 provides a low temperature output 24 out the low temperature cooler 23 is a low temperature line 26 to the 4-way valve 16 traced back and flows into this, giving a low-temperature entrance 27 represents.

In the low-temperature cooling circuit 4 is downstream of the 4-way valve 16 and upstream of the low temperature radiator 23 a water pump 28 arranged so that coolant can circulate. The water pump could also, depending on the design, in the low temperature line 26 be arranged.

An exhaust gas cooler 29 as EGR cooler 29 is via an EGR cooler line 31 and an EGR cooler line 32 with the 4-way valve 16 in connection. From the 4-way valve branches the EGR cooler line 31 at an EGR cooler outlet 33 from, with the EGR cooler line 32 at an EGR cooler input 36 in the 4-way valve 16 empties. The flow direction of the coolant is represented by arrowheads.

In a warm-up phase of the internal combustion engine 2 , is the 4-way valve 16 switchable so that the exhaust gas cooler 29 with its coolant circuit with the high-temperature circuit 3 or with the pump line 9 communicates. The low temperature circuit 4 is during the warm-up phase of the EGR cooler 29 or the EGR cooling circuit separately. When the warm-up phase is over, the EGR cooler will start 29 or its cooling circuit with the low-temperature circuit 4 connected, closing the path with respect to the high-temperature circuit 3 in the 4-way valve 16 a coolant flow in the lines 13 and 18 is prevented.

So can the warm-up phase of the internal combustion engine 2 by a heat transfer in the EGR cooler 29 absorbed heat to the coolant in the high-temperature cooling circuit 3 be shortened.

At the in 2 illustrated embodiment, the control system 14 two switching valves 37 and 38 on.

The switching valve 37 is as a low temperature valve 37 in the low temperature line 26 the low-temperature cooling circuit 4 arranged. The switching valve 38 is as a high temperature valve 38 in the high temperature input line 13 arranged. Between both switching valves 37 and 38 is a connection line 39 arranged in which the only EGR cooler 29 is arranged.

The connection line 39 is downstream of the EGR cooler 29 continues and has departures 41 and 42 on the one hand to the low-temperature cycle 4 or to the low temperature line 22 and on the other to the high-temperature cycle 3 or to the pump connection line 9 on.

In the warm-up phase of the internal combustion engine 2 is the low temperature valve 37 closing the low-temperature circuit switchable, so that the EGR cooler 29 of coolant of the high-temperature circuit 3 flows through. The recirculated exhaust gases pass through the EGR cooler 29 their heat directly to the coolant of the high-temperature circuit 3 from. Downstream of the EGR cooler 29 Both coolant flows can mix together slightly. In this respect, the two switching valves 37 respectively. 38 be designed as infinitely adjustable valves, which the respective coolant circuit 3 and 4 adjusted in the flow amount flowing coolant adapted to control each other, depending on which operating parameters and which coolant temperature is detected. When the warm-up phase is over, the switching valve is 38 The administration 13 switched closing, so that coolant can not circulate in this line. The switching valve 37 is then open.

In the figures, exhaust pipes and / or other components of the exhaust gas recirculation system (EGR or EGR = exhaust gas recirculation) are not shown.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• AT 001620 U1 [0002, 0002]
• DE 10143091 A1 [0003]
• DE 19633190 A1 [0004]
• EP 1055813 A2 [0005]
• DE 19924398 A1 [0005]
• DE 60029874 [0006]
• DE 69912173 T2 [0007]
• DE 102005042396 A1 [0008]
• JP 20052113761 [0009]
• KR 1020020043726 A [0010]
• DE 60024390 T2 [0011]
• US 6244256 B1 [0011]
• DE 60304875 T2 [0012]
• WO 2004/22940 [0012]
• DE 102008036277 A1 [0013]
• DE 102005055323 A1 [0014]
• EP 1772612 A1 [0015]
• WO 2005/073535 [0016]

Claims (7)

Cooling system of an internal combustion engine ( 2 ) containing a high-temperature coolant circuit ( 3 ) with a high temperature cooler ( 8th ) and a low-temperature coolant circuit ( 4 ) with a low-temperature cooler ( 23 ), wherein the internal combustion engine ( 1 ) an EGR cooler ( 29 ) connected to the low-temperature coolant circuit ( 4 ), which of the high-temperature coolant circuit ( 3 ), characterized in that a control system ( 14 . 16 ; 14 . 37 . 38 ) the EGR cooler ( 29 ) in a warm-up phase with the high-temperature coolant circuit ( 3 ), and after completion of the warm-up phase, the connection to the high-temperature coolant circuit ( 3 ), so that the EGR cooler ( 29 ) after completion of the warm-up phase again with the low-temperature coolant circuit ( 4 ) connected is. Cooling system according to claim 1, characterized in that the control system ( 14 . 16 ; 14 . 37 . 38 ) between the high-temperature cooling circuit ( 3 ) and the low-temperature cooling circuit ( 4 ) is arranged. Cooling system according to claim 1 or 2, characterized in that the EGR cooler ( 29 ) with the control system ( 14 . 16 ; 14 . 37 . 38 ). Cooling system according to one of the preceding claims, characterized in that the control system ( 14 . 16 ) as a 4-way valve ( 16 ) executed a low temperature input ( 27 ), a low temperature output ( 24 ), a high temperature input ( 17 ), a high-temperature outlet ( 19 ), an EGR cooler outlet ( 33 ) and an EGR cooler input ( 36 ) having. Cooling system according to one of the preceding claims, characterized in that the control system ( 14 . 37 . 38 ) of two switching valves ( 37 . 38 ), wherein a low-temperature valve ( 37 ) in the low-temperature cycle ( 4 ) and a high-temperature valve ( 38 ) in the high-temperature cooling circuit ( 3 ) is arranged. Cooling system according to claim 5, characterized in that the EGR cooler ( 29 ) in a connection line ( 39 ) between the two switching valves ( 37 . 38 ) is arranged. Cooling system according to claim 6, characterized in that the connecting line ( 39 ) downstream of the EGR cooler ( 29 ), whereby an exit ( 41 ) to the low-temperature cooling circuit ( 4 ) and an exit ( 42 ) to the high-temperature cooling circuit ( 3 ) from the connection line ( 39 ) branch off.

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