DE102005035121B4 - Device for heating a motor vehicle - Google Patents

Abstract

Device for heating a motor vehicle with an internal combustion engine (1) which is cooled by means of a coolant circulated by a coolant pump (7), with a) a coolant circuit with a through the coolant pump (7), the internal combustion engine (1) and a cooler branch (6a) Vehicle radiator (8) and a thermostat (6), b) a bypass branch (6b) leading through the coolant pump (7) and the internal combustion engine (1), which bypasses the vehicle radiator (8) in a bypass circuit, c) one through the coolant pump ( 7), the internal combustion engine (1) and a ventilation branch (9a) leading ventilation circuit with a water tank (9), d) a heating circuit leading through the coolant pump (7), the internal combustion engine (1) and a heating branch (4a) with a heating heat exchanger ( 4), e) an additional valve (6bv) controllable by an engine control unit (16), with which the bypass circuit can be closed when the thermostat (6) is closed, f) one through the Coolant pump (7) and the internal combustion engine (1) leading additional bypass branch (6c), which is arranged parallel to the bypass branch (6b) with an additional valve (6bv) and bypasses the vehicle radiator (8) without the integration of a heat exchanger, the thermostat (6) with a The expansion element works and the coolant flowing in the additional bypass branch (6c) bypasses the expansion element of the thermostat (6).

Description

The invention relates to a device for heating a motor vehicle with improved utilization of waste heat from the engine for cabin heating purposes and to save fuel.

It is known to use thermal management measures to reduce fuel consumption in modern cars. In particular, rapid heating of the coolant and engine oil and thus also of the engine components as well as raising the thermostat opening temperature under partial load are effective means of improving fuel consumption.

It is also known to use, in addition to the thermostats usually used to regulate the heat output at a vehicle radiator, further coolant valves which intervene in the coolant flow through the internal combustion engine and / or the heater.

It is also known to intervene on the air side in the heat output of the heating heat exchanger in order to regulate the temperature of the air flowing into the cabin or to limit the heating output.

In the prior art, there are a large number of suggestions as to how improvements with regard to heating, fuel consumption and / or control / system application can be achieved here. This is for example in the publications DE 102 25 469 C1 , DE 34 40 504 A1 , DE 198 58 988 A1 , U.S. 5,203,788 A , DE 103 16 017 A1 , US 2003/0 177 986 A1 , DE 199 32 313 A1 , DE 195 08 102 C1 , DE 100 62 976 A1 , DE 196 46 123 A1 , DE 44 31 041 A1 , DE 22 06 266 C2 and DE 197 37 818 A1 the case.

The DE 34 40 504 A1 discloses, avoiding an expansion thermostat, a cooling system with 5 valves controllable by the engine management system for the separate cooling of the cylinder head and cylinder block by two separate coolant pumps.

Similar to the US 2003/0177986 A1 , according to which 6 valves controllable by the engine control are provided.

The DE 198 58 988 A1 in a heating and cooling circuit system deals with the avoidance of an excessively high discharge temperature of the air exiting the heating heat exchanger. Thereafter, a valve can be provided for switching off a coolant flow through the heating system heat exchanger.

The DE 197 37 818 A1 discloses a thermostat in a cooling system, the opening temperature of which is influenced by two parallel bypass lines which flow towards a wax can acting as an expansion element and one of which can be switched off.

The DE 102 25 469 C1 discloses a multi-zone air conditioning system in which both the heating heat exchanger and the air flow duct are divided into 3 zones and the different zones can be controlled separately with regard to coolant flow and air flow.

The DE 199 32 313 A1 discloses a special rotary slide valve as a control unit for different coolant flows instead of an expansion thermostat.

The DE 103 16 017 A1 discloses independently controllable coolant flow rates through the cooler, the bypass and the heating heat exchanger via valves.

The DE 195 08 102 C1 discloses a thermal management strategy using the radiator fan and a temperature-independent valve for various coolant flows.

The DE 100 62 976 C1 discloses a control strategy for vehicle interior temperature for various interior areas. Similar to the DE 196 46 123 A1 .

The DE 44 31 041 A1 discloses a control strategy for the cabin air in order to avoid heat losses, in particular when the engine is cold, due to the cabin air flowing out.

The DE 22 06 266 C discloses a strategy for quickly warming up the engine by independently controlling the coolant flow rate through the cylinder head and cylinder block.

The object of the invention is to provide the heating system DE 10 2004 058 869 to develop further and to provide a fuel-saving cooling and heating system that is superior to the state of the art cited.

This object is achieved with the device according to claim 1.

The dependent claims relate to preferred embodiments of the invention.

1. a) einem durch die Kühlmittelpumpe (7), die Brennkraftmaschine (1) und einen Kühlerzweig (6a) führenden Kühlerkreislauf mit einem Fahrzeugkühler (8) und einem Thermostaten (6),
2. b) einem durch die Kühlmittelpumpe (7) und die Brennkraftmaschine (1) führenden Bypasszweig (6b), welcher den Fahrzeugkühler (8) in einem Bypasskreislauf umgeht,
3. c) einem durch die Kühlmittelpumpe (7), die Brennkraftmaschine (1) und einen Entlüftungszweig (9a) führenden Entlüftungskreislauf mit einem Wasserbehälter (9),
4. d) einem durch die Kühlmittelpumpe (7), die Brennkraftmaschine (1) und einen Heizungszweig (4a) führenden Heizungswärmetauscherkreislauf mit einem Heizungswärmetauscher (4),
5. e) einem von einer Motorsteuerung (16) ansteuerbaren Zusatzventil (6bv), mit welchem der Bypasskreislauf bei geschlossenem Thermostaten (6) geschlossen werden kann, und
6. f) einem durch die Kühlmittelpumpe (7) und die Brennkraftmaschine (1) führenden Zusatzbypasszweig (6c), welcher
7. g) parallel zum Bypasszweig (6b) mit Zusatzventil (6bv) angeordnet ist und ohne Einbindung eines Wärmetauschers den Fahrzeugkühler (8) umgeht,
8. h) wobei der Thermostat (6) mit einem Dehnstoffelement arbeitet und das im Zusatzbypasszweig (6c) strömende Kühlmittel das Dehnstoffelement des Thermostaten (6) umgeht.

The invention relates to a device for heating a motor vehicle with an internal combustion engine ( 1 ), which by means of a coolant pump ( 7th ) circulated coolant is cooled,
With

1. a) one through the coolant pump ( 7th ), the internal combustion engine ( 1 ) and a radiator branch ( 6a ) leading cooler circuit with a vehicle cooler ( 8th ) and a thermostat ( 6th ),
2. b) one through the coolant pump ( 7th ) and the internal combustion engine ( 1 ) leading bypass branch ( 6b ), which the vehicle radiator ( 8th ) bypasses in a bypass circuit,
3. c) one through the coolant pump ( 7th ), the internal combustion engine ( 1 ) and a ventilation branch ( 9a ) leading ventilation circuit with a water tank ( 9 ),
4. d) one through the coolant pump ( 7th ), the internal combustion engine ( 1 ) and a heating branch ( 4a ) leading heating heat exchanger circuit with a heating heat exchanger ( 4th ),
5. e) one of a motor controller ( 16 ) controllable additional valve ( 6bv ), with which the bypass circuit is activated when the thermostat is closed ( 6th ) can be closed, and
6. f) one by the coolant pump ( 7th ) and the internal combustion engine ( 1 ) leading additional bypass branch ( 6c ), which one
7. g) parallel to the bypass branch ( 6b ) with additional valve ( 6bv ) is arranged and the vehicle radiator ( 8th ) bypasses,
8. h) where the thermostat ( 6th ) works with an expansion element and that in the additional bypass branch ( 6c ) flowing coolant the expansion element of the thermostat ( 6th ) bypasses.

The invention is described in more detail below with reference to the figures:

1 shows a heating circuit. He has a heating branch 4a with heating heat exchanger 4th on which the heat from the cooling of the internal combustion engine 1 relates.
A preferably provided electric valve 2 (Throttle element) sets a defined coolant throughput as independently as possible of the speed of the internal combustion engine, which, for example, is determined by the coolant temperature of the sensor 15th in the engine control unit 16 and with the aid of the heat exchanger map depending on the fan position, the ambient temperature and the current position of the air temperature control flap 5 into a theoretical air temperature of the air mass flow 20th is converted at the outlet from the heater. If this temperature deviates from the target temperature, the air temperature control flap regulates 5 to. Is the position of the air temperature control flap 5 very close to one of the two end stops, the coolant throughput is determined by opening and closing the valve 2 changed so that again a position with a sufficient safety margin for robust temperature control with the air temperature control flap 5 consists. To increase the control quality, it is particularly advantageous if, in addition to calculating the temperature of the air mass flow 20th a sensor whose temperature measures.
From the heating system heat exchanger 4th the coolant flows over the thermostat 6th and the coolant pump 7th back to the internal combustion engine 1 . Next to the heating branch 4a the coolant flows when the thermostat is closed 6th additionally through the bypass branch 6b . An additional valve 6bv is from the engine control 16 controllable and can, if necessary, the bypass branch 6b shut down. An additional bypass branch 6c parallel to the bypass branch 6b bypasses the thermostat 6th .
As is generally the case with air-conditioning systems that are preferably regulated on the air side, the heating heat exchanger takes over in the event of excess heat 4th the temperature control flap 5 the temperature control of the air mass flow 20th by the heated air mass flow 21 an unheated bypass air mass flow 22nd is added.

2 shows an exemplary map with curves for the flow dependency of the mean temperature of the effective heat-active mass in the heating branch on the one hand and curves of the associated useful heat extraction at the heating heat exchanger on the other. The effective heat-active mass consists in particular of the flow line with valve 2 , the heating system heat exchanger 4th and the return line and is mass averaged according to their local temperature distribution and component mass. The heating heat exchanger 4th This data record is characterized by the fact that it is also effective for small coolant throughputs.

For an exemplary operating point with a flow temperature of + 80 ° C and an ambient temperature of + 7 ° C or an outlet temperature of + 7 ° C from the air conditioning evaporator, the heat extraction at the heating heat exchanger depends to a large extent on the current blower setting or the air mass flow 21 .

Of the families of curves, pairs of curves with the same air mass flow are to be compared. If one compares, for example, the associated curves for 5 kg / min air mass flow, the curve for the mass-averaged temperature shows that with an unthrottled ie high coolant volume flow, the mass-averaged temperature is only slightly below the flow temperature of 80 ° C. In contrast to this, the coolant throughput is throttled from 12 l / min to approx. 1.4 l / min with a heating power requirement of, for example, 5 kW, thus reducing the average temperature to below 50 ° C achieved. If the heating power requirement is less than 1 kW, the average temperature can even be reduced to below 40 ° C by reducing the coolant throughput to very low values of 0.3 l / min and less.

As a throttle organ 2 an electrically operated valve is preferably not used, but a purely thermostatically operated valve, which is now in the return of the heating branch or even in a largely cooled zone of the heating heat exchanger 4th is arranged. This valve is, for example, above + 25 ° C in the closed end position and has a small leakage flow in order to send the coolant temperature information to the thermostatic valve 2 to transport.

Especially for engines with a heating deficit, but also to maximize cabin heating in winter, it is particularly advantageous if the bypass branch in the cooling circuit when there is a high heating requirement 6b is also closed like the radiator branch 6a and the vent branch 9a . This is generally advantageous for maximizing the heating effect.

In the heating circuit according to 1 this is where the additional valve comes in 6bv to use and the return from the water tank 9 takes place on the cold side of the thermostat 6th . The additional valve is used when there is a high heating requirement and low engine output 6bv closed, so that not only the heat-active mass of the heating branch is minimized, but also the heat-active mass of the engine. As soon as there is an excess of heat for the cabin heating, it is particularly advantageous in this arrangement to additionally throttle the coolant throughput in the heating branch.

In a particularly advantageous embodiment of the heating circuit, the coolant return line of the heating branch is used 4a downstream of the thermostat 6th and upstream of the coolant pump 7th arranged.

According to one embodiment of the heating circuit, there is an additional bypass branch 6c , parallel to the bypass branch 6b with additional valve 6bv , provided, but not on the thermostat 6th ends, but downstream, preferably directly in the vicinity of the pump inlet of the coolant pump 7th . In its simplest form, this is a line with a small cross-section with a corresponding throttling effect or a line with a thermostatic valve 6cv that opens, for example, from a coolant temperature of 60 ° C. Instead of the additional bypass branch 6c Motor-internal channels can also be used. In both cases, ie with and without a thermostatic valve 6cv , is the flow in the bypass branch 6b with the thermostat closed 6th and open bypass valve 6bv many times larger than in the additional bypass branch 6c . This specification with regard to the flow rate is important on the one hand for good heating performance and on the other hand to limit the flow-dependent cooling effect on the cylinder liners with and without heating.

In terms of maximizing the heating output is the thermostatic valve 6cv particularly helpful, as it ensures that the main coolant throughput through the heating system heat exchanger down to a minimum temperature of the engine coolant 4th goes.

For the heating circuit according to 1 is the cold return line of the coolant in the heating branch upstream of the position 7e of the additional bypass branch 6c and is the bypass branch 6b so around the thermostat 6th arranged that its coolant throughput when electrically opening the additional valve 6bv on the expansion element of the thermostat 6th flows past. In 1 is as a valve 2 a thermostatic valve is particularly suitable. However, an electronic valve with appropriate control can also be used. In this case, it is particularly advantageous to provide a "fail-safe" protection, which in the event of an excessive engine temperature, for example due to a failure of the additional valve 6bv the valve 2 opens completely and thus at least partially opens the vehicle radiator 8th leads.

The additional bypass branch 6c , with the removal of the coolant from warm zones of the cooling system and its specific mouth at the position 7e downstream of the thermostat 6th and upstream of the coolant pump 7th costs without the thermostatic valve 6cv and from its opening potential at maximum heating power in winter, as it reduces the temperature stratification on the engine.

The heating circuit is particularly easy to tune, albeit the additional bypass branch 6c has a regulation of the coolant throughput. In the simplest case, this is again done electrically, ie via one from the engine control 16 adjustable thermostatic valve 6cv .

In a further refinement of the heating circuit shows 3 two more coolant branches 6d for an optional engine oil cooler 30th and 6e for an optional transmission oil cooler 40 . Again, provide optional thermostats 6dv and 6ev or el. valves ensure that when the coolant is cold, on the one hand, the heating performance is improved and, on the other hand, the available heat initially benefits the engine during warm-up.

With an el. Valve 2 switched off heating branch 4a It is particularly advantageous if, starting from the cold engine operating state, initially no coolant flows through the engine, then the additional bypass branch at a first switching temperature of the coolant 6c opens at a second switching temperature, the coolant branch 6d opens and, after further engine heating, the coolant branch at a third switching temperature 6e .

The particularly advantageous embodiment according to 4th shows the possibility of an engine oil cooler 30th and / or a transmission oil cooler 40 to be integrated in such a way that the coolant is directly at the pump outlet of the coolant pump 7th or can be taken directly in the vicinity of the engine inlet. The total coolant throughput through the engine is thus back to the coolant throughput in the additional bypass branch at the points that are decisive for the heat transfer on the water side 6c limited.
The advantages of this specific integration of the engine oil cooler 30th and / or the transmission oil cooler 40 with regard to the control quality are so significant that it is also easily possible to connect the heating return to the position 7e to work like in 5 shown.

A special configuration shows 6th with additional integration of an engine oil cooler 30th and a transmission oil cooler 40 . As in 7th and 8th by the dashed connecting line from the thermostatic valve 6cv for motor control 16 is shown, electrical control of the thermostatic valve can also be used 6cv through the engine control 16 be provided.

In the design according to 9 , is the thermostatic valve 6cv a differential temperature control valve and contains, in particular, a sensor actuator that detects the temperature difference between the engine inlet and engine outlet and ensures that the temperature difference does not become greater than a defined default value. In the exemplary embodiment shown, a first minimum sensor volume flow is used in the branch for this purpose 6t1 led to a first expansion cell and tempered this and a second minimum sensor volume flow in the branch 6t2 to a second expansion cell. The two partial flows are then, for example, via the line 6t3 derived.

List of reference symbols

1

Internal combustion engine

2

Valve

4th

Heating heat exchanger

4a

Heating branch

5

Air temperature control flap

6th

thermostat

6a

Radiator branch

6b

Bypass branch

6bv

Additional valve

6c

Additional bypass branch

6cv

Thermostatic valve

6d

Coolant branch

6dv

6e

thermostat

6ev

thermostat

6t1

branch

6t2

branch

6t3

management

7th

Coolant pump

7e

position

8th

Vehicle radiator

9

Water tank

9a

Vent branch

15th

sensor

16

Engine control

20th

Air mass flow

21

heated air mass flow

22nd

Bypass air mass flow

30th

Engine oil cooler

40

Transmission oil cooler

Claims (9)

Device for heating a motor vehicle with an internal combustion engine (1), which is cooled by means of a coolant circulated by a coolant pump (7), with a) a coolant circuit leading through the coolant pump (7), the internal combustion engine (1) and a cooler branch (6a) a vehicle radiator (8) and a thermostat (6), b) a bypass branch (6b) leading through the coolant pump (7) and the internal combustion engine (1), which bypasses the vehicle radiator (8) in a bypass circuit, c) one through the coolant pump (7), the internal combustion engine (1) and a ventilation branch (9a) leading ventilation circuit with a water tank (9), d) a heating circuit with a heating heat exchanger leading through the coolant pump (7), the internal combustion engine (1) and a heating branch (4a) (4), e) an additional valve (6bv) controllable by an engine control unit (16), with which the bypass circuit can be closed when the thermostat (6) is closed, f) a dur ch the coolant pump (7) and the internal combustion engine (1) leading additional bypass branch (6c), which is arranged parallel to the bypass branch (6b) with an additional valve (6bv) and without Integration of a heat exchanger bypasses the vehicle radiator (8), the thermostat (6) working with an expansion element and the coolant flowing in the additional bypass branch (6c) bypasses the expansion element of the thermostat (6). Device according to Claim 1 , characterized in that the coolant return of the additional bypass branch (6c) to the internal combustion engine (1) takes place at a position (7e) which is downstream of the thermostat (6) and upstream of the coolant pump (7). Device according to one of the Claims 1 - 2 , characterized in that the additional bypass branch (6c) is a line with a small cross section, so that the line has an inside diameter of less than 6 mm. Device according to one of the Claims 1 - 3 , characterized in that the additional bypass branch (6c) has a passive and non-thermostatic throttle element. Device according to Claim 4 , characterized in that the additional bypass branch (6c) has, as a passive and non-thermostatic throttle element, a perforated diaphragm with a diameter of less than 6 mm. Device according to one of the Claims 1 - 5 , characterized in that the bypass branch (6b) and the additional bypass branch (6c) do not contain a heat exchanger. Device according to one of the Claims 1 - 6th , characterized in that the additional bypass branch (6c) does not contain a valve. Device according to one of the Claims 1 - 7th , characterized in that it is installed in a motor vehicle with an air-side temperature control, in which the temperature of the air (20) conveyed into a cabin of the motor vehicle by means of the mixture via an air temperature control flap (5) of an air flow (4) conveyed through the heating system heat exchanger (4) 21) is set with a non-heated bypass air mass flow (22). Device according to Claim 8 , characterized in that a valve (2) is integrated in the heating circuit (4a) leading through the heating branch.

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