DE19948890A1 - Oscillating cooling water circuit - Google Patents

Abstract

The invention relates to a device comprising a heat generating unit (1) having an elevated operating temperature in an operating phase and a cooling system (2, 10, 11, 12, 13) having a cooling medium which flows into or by the unit (1). The flow speed of the cooling medium in or to the unit (1) can be modulated with respect to size and/or direction.

Description

The present invention relates to a front direction with a heat generating unit and with a cooling system such as combustion engines, fuel cells and / or transmissions.

Devices with heat generating units, such as for example, internal combustion engines that he operated at high operating temperatures usually a cooling system, for example one Cooling water circuit in which the cooling medium circulates run through the device for removing the there resulting heat is conducted. According to the state of the Technology is usually something for internal combustion engines ser used as cooling medium and the water cycle is powered by a water pump. It takes according to the prior art, the water pump with the Starting the engine and pumping up Start on cooling water by the engine.  

However, this has the disadvantage that a cold Mo door is cooled unnecessarily in the cold start phase and the engine warm-up phase is extended with all disadvantages for pollutant emissions and Fuel consumption during the warm-up phase.

To solve these problems, DE 38 13 217 C2 discloses a temperature-controlled electromagnetic diaphragm water pump, which only works with a cylinder cooling water temperature of 80 ° C put into operation becomes. This avoids the during cold start Cooling by means of the cooling water circuit.

A disadvantage of this method is that heat generating units, such as burning motors, even during the warmth running phase an uneven heat distribution and so called "hot spots", for example in the area of Have exhaust valves in which the engine is extremely is heated quickly. A shutdown of the cooling circuit here leads to a very local overheating of the Mo tors and possibly to destroy the exhaust veins tile. A complete shutdown of the water pump, as disclosed in DE 38 13 217 C2 is therefore not sensible.

The object of the present invention is therefore a Device with a heat generating unit for To make available at which one the respective Be Drive state of the device adapted cooling the Unit is effected without local overheating to accept.

This task is accomplished by the device according to An claim 1 and the method according to claim 12 solved.  

Advantageous further developments of the invention Devices and the method according to the invention are described in the dependent claims.

The device according to the present invention has a heat generating unit and a cooling system with a cooling medium that ent in or on the unit long flows, for example through an engine block. According to the invention, the flow rate of the cooling medium in or on the unit in size and / or direction can be modulated. So it is possible that Switch the cooling water circuit on or off. The Cooling water circuit is, for example, in the Starting phase essentially switched off and single Lich an oscillating movement of the cooling medium carried out. This leaves almost all of it in heat generated by the device within the unit, since the cooling medium only slightly back and forth moved here. Nevertheless, he is evenly distributed generated heat within the unit, for example the engine block ensures that for an effective same cooling of the "hot spots" is ensured. A total of becomes a very rapid warming of the unit causes at start, the dreaded "hot spots "with a standing or slow cooling water circuit run be avoided.

Even in continuous operation, after reaching the operating temperature temperature, the flow rate of the cooling be modulated mediums. This can, for example the effective mean flow velocity of the Coolant lowered and consequently the operating temperature rature of the unit can be increased by the Mo dulation of the flow rate nevertheless a effective cooling of the "hot spots" is effected.  

By modulating the flow rate at Operating temperature can continue the Temperaturdif reference between the inlet and the outlet of the cooling can be reduced by means of in or on the unit.

The flow rate of the cooling medium can still with different amplitude modu be lated. For example, with increased Heat production in the short term the modulation amplitude be increased in order to cool the "hot spots" more effectively len.

To implement such a modulation are suitable for the cooling water circuit, for example gelable electric pumps, from flow to return are switchable. Also adjustable, mechanical Pumps with only one pump direction can be used provided they have a corresponding mechanical Switch, for example a rotary valve, nachge is switched. In the latter case, for example These are almost rectangular courses of the flow speed of the cooling medium are generated during any with an adjustable electric pump Curves of the flow rate of the cooling medium, for example made of sinusoidal can.

The modulation can be controlled via a time pro grams, for example for cold start operation a temperature sensor at any point, at for example in the cylinder head gasket, in its order the "hot spots" in internal combustion machines are located, controlled.

In an advantageous development, this can direction to be further developed so that a  latent heat storage is provided over the front or a certain percentage during the cold start phase the cooling medium is heated and then possibly oscillating, in the heat generating Unit is transported. This means that la heat accumulators do not contain the entire cooling medium cooling circuit, but only one Fraction of the cooling medium to be heated. This enables light a higher efficiency of the latent heat storage chers. The heat accumulator can be arranged in this way be that the cooling medium from the unit in the heat memory and directed back into the unit becomes. Ideally, there is the latent Heat storage in the middle of the flow section or Flow path of the cooling medium within the heat unit. Through an oscillating back and forth Moving the coolant it is possible the heat generating unit before or during the Cold start operation to heat up the losses are minimized by dead volumes of the coolant.

The following are some examples of one device according to the invention are described.

Show it:

Fig. 1 a heat generating device;

Fig. 2 is a further heat generating device with latent heat storage;

Fig. 3 heat generating devices;

FIG. 4 shows various modulation modes for the flow rate of the cooling medium; and

Fig. 5 different modes of modulation for the flow rate of the cooling medium.

Fig. 1 shows an inventive device with a heat generating unit 1 , a coolant pump 2 and a rotary valve 3rd The coolant flows from the coolant pump 2 via the supply lines 12 to the rotary valve 3 and there via an inlet 22 , a passage 15 and an outlet 23 to a supply line 11th The supply line 11 is connected to the heat generating unit 1 . The coolant enters the rotary valve 3 from the heat-generating unit 1 via a discharge line 10 , an inlet 20 and flows through the rotary valve 3 via a connecting line 20 to its outlet 21 , from where it flows back to the coolant pump 2 via a discharge line 13 . If the coolant pump 2 is now put into operation, there is a constant coolant flow through the heat generating unit 1 . If the rotary valve 3 is also put into operation, the volume of the coolant shown hatched in FIG. 1 is oscillated back and forth, since the rotary valve 3 periodically reverses the direction of flow in the lines 10 and 11 . Depending on the speed of the rotary valve, the oscillation is faster or slower. If the individual positions of the rotary valve continue to be maintained for different lengths of time, an average flow velocity can result in a direction on which an oscillating movement of the coolant is modulated.

Fig. 2 shows a further device in the ent speaking components with appropriate reference characters as in Fig. 1 and the descriptive description is therefore omitted. In addition to Fig. 1 in Fig. 2, a latent heat storage 30 vorhan the, from the heat-generating unit 1 Kühlmit tel is supplied via a coolant supply 31, the device leaves the latent heat storage via a coolant drain 32 again and to the heat-generating unit 1 is returned. If during or before the cold start operation and the warm-up phase by the coolant pump 2 and the rotary valve 3, a uniformly oscillating coolant flow in the lines 10 and 11 is effected, the mean speed of the coolant should be zero, the hatched in Fig. 2 drawn portion of the coolant between the heat generating unit 1 and the latent heat accumulator 30 reciprocating and can thus heat the heat generating unit. After the warm-up phase has ended, the latent heat store can be decoupled from the cooling water circuit by appropriately arranged valves (not shown here).

FIG. 3 shows a further device, several heat generating units 1.1 and 1.2 being provided in FIG. 2. Each of these units is assigned its own rotary valve 3.1 or 3.2 for independent control of the modulation and flow rate of the cooling medium for each of the heat-generating units 1.1 or 1.2 . The function of the individual construction elements in Fig. 3 corresponds to the function of the construction elements in Fig. 1, so that they are denoted by corresponding reference numerals and for the descrip tion of the function reference is made to the description of FIG. 1.

FIG. 4 shows various forms of modulation of the speed of the coolant, in or on the heat-generating unit, as can be generated, for example, with the device according to FIG. 1.

Fig. 4A shows a smooth back and forth movement of the coolant, the average speed V of the coolant is equal to zero. This operation is carried out, for example, at the beginning of the cold start phase. The speed of the coolant is constant in one valve position and is reversed when the valve is turned to the next valve position. In this operation, almost all of the heat of the heat-generating unit 1 remains within this unit 1 , but an equal heat distribution is brought about in the unit and so-called "hot spots" are cooled.

FIG. 4B shows an asymmetrical velocity distribution of the coolant, thereby resulting in a re mittle velocity v is greater than 0. The rotary valve is left in one of the positions for a longer period of time than in the other position, so that the flow rate is maintained longer in one direction than in the other. This results in a certain heat removal from the heat generating unit 1 , but good cooling of the "hot spots" is achieved. Such operation can occur, for example, in the transition from the cold start phase of an internal combustion engine to the permanent operating phase.

Fig. 4C shows such a transition of a heat-generating unit 1 of the cold start phase to reach the operating temperature. At the beginning, the flow rate of the coolant oscillates back and forth as shown in FIG. 4A, whereby the heat is left in the heat generating unit and only the "hot spots" are cooled. When the temperature of the heat-generating unit 1 reaches the continuous operating temperature, the rotary valve is brought into a position and held there in which a constant coolant flow through the heat-generating unit takes place.

Fig. 4D shows the control of the coolant flow in a further example. In this case, no cooling takes place of the remains at the very beginning of the cold start phase by the cooling medium, so that the entire heat from said heat generating unit 1 is generated in this unit. 1 When a critical temperature is reached at the so-called "hot spots", an oscillating back and forth movement of the coolant is initiated by rotating the rotary valve. When the continuous operating temperature is reached, the rotary valve is held in a position in which there is a constant coolant flow through the heat-generating unit 1 .

The corresponding critical temperatures of the "hot spots" or the heat-generating unit 1 , for example an internal combustion engine, can be detected in example by temperature sensors that can be arranged in the cylinder head gasket. This data is then used to control the rotary valves and thus to regulate the coolant flow.

Fig. 5 shows various forms of modulation of the speed of the coolant in or on the heat-generating unit, such as can be generated for example by means of an electrically controllable pump instead of a mechanical pump with a rotary valve.

Fig. 5A shows a uniform oscillating reciprocating movement of the coolant, the average velocity v of the refrigerant is equal to zero. This operation is, for example, at the beginning 'of the cold-start period performed to the generated in the heat he generating unit 1 heat within the A standardized to leave 1, but to cause thermal uniform distribution in the unit and to effectively cool so-called "hot spots".

FIG. 5B shows the operation during the normal operating condition with Be operating temperature, wherein a modulation is applied here to a uniform flow of the coolant with v <0,. As a result, better heat distribution and cooling of the "hot spots" is achieved within the heat-generating units 1 .

Fig. 5C shows the modulation of a uniform coolant flow with v <0 with different Am plitude. Such amplitude modulation is useful for example when increased heat generation in the engine, for example at increased power, the "hot spots" must be cooled more sen, without an increased heat removal from the heat generating unit is actually required.

Fig. 5D describes the transition to a heat erzeu constricting unit, for example a Verbrennungsmo gate, from cold start to reach the operating temperature. At the start of the cold start, the coolant speed is only oscillatingly modulated in a reciprocating manner. As the operating temperature increases, the modulation is increased for better cooling of the "hot spots". When the operating temperature is reached, there is an effective mean flow of the coolant, which in turn, however, has a slight modulation to equalize the temperatures within the engine block.

Fig. 5E shows the modulation of the coolant flow at a temperature-dependent control.

If the temperature T of the engine is below a limit temperature T _G , the mean directional flow of the cooling medium is reduced, but for the cooling of the "hot spots" this flow is characterized by a modulation. If the temperature T exceeds the limit temperature T _G , the flow rate of the coolant is increased, and the modulation is omitted in order to remove a maximum of the heat generated.

In summary, the advantages of device according to the invention and of the invention be described. For one thing, egg ne rapid warming of the heat generating unit be achieved with all the associated advantages, for example in the case of the internal combustion engine with regard to Fuel yield and pollutant emissions, at a fuel cell in terms of efficiency or for a gearbox regarding the viscosity of the gearbox oil and thus also the efficiency. Here however, there will be local overheating within the one effectively avoided and overall the temperature level within the heat generating unit nivel and the temperature difference between the on run and the outlet of the coolant in continuous operation reduced. Last but not least, it is with the fiction measured device and the inventive method possible while avoiding local overheating  Heat generating unit with increased operation operating temperature.

Claims (21)

1. Device with a heat generating unit ( 1 ), with an increased operating temperature in an operating phase and a cooling system ( 2 , 10 , 11 , 12 , 13 ) with a cooling medium which flows in or on the unit ( 1 ), characterized that the flow rate of the cooling medium in or on the unit ( 1 ) can be modulated in size and / or direction. 2. Device according to that of the previous An saying, characterized in that the river speed by a in the pump direction switchable pump and / or a switching device device for the flow direction can be modulated. 3. Device according to the preceding claim, characterized in that the switching device tion is a rotary valve. 4. Device according to one of the preceding An sayings, characterized in that the river alternating direction of the coolant reversible and / or the flow rate of the  The coolant can be alternately reduced and increased is cash. 5. Device according to one of the preceding An sayings, characterized in that the Flußge speed can be modulated periodically. 6. Device according to one of the preceding An sayings, characterized in that the Flußge modulate speed with variable amplitude is cash. 7. Device according to one of the preceding An sayings, characterized in that they have a has latent heat storage for heating a certain amount of cooling medium and / or during the heating of the unit the operating temperature. 8. Device according to one of the preceding An sayings, characterized in that on or in temperature of the heat generating unit sensor is arranged. 9. Device according to one of the preceding An sayings, characterized in that the heat generating unit an internal combustion engine ne is.   10. The device according to the preceding claim, characterized in that the combustion engine a cylinder block, a cylin derkopf and one between cylinder block and Zy cylinder head gasket points. 11. The device according to the preceding claim, characterized in that a temperature sensor arranged in or on the cylinder head gasket is. 12.. Method for cooling a heat-generating unit which has an increased operating temperature in an operating phase
a cooling medium flowing in or along the unit for cooling,
characterized in that
the flow rate of the cooling medium in or on the unit ( 1 ) is at least temporarily modulated in size and / or direction. 13. The method according to the preceding claim, characterized in that the river speed is periodically modulated. 14. Procedure according to one of the two previous Claims, characterized in that the river speed with variable amplitude modu is gated.   15. Procedure according to one of the three preceding An sayings, characterized in that the unity on operation during a cold start phase temperature is warmed, at least while Part of the cold start phase the river direction of the cooling medium alternately reversed and / or the flow rate alternately is increased and decreased. 16. The method according to the preceding claim, characterized in that at least during egg nes part of the cold start phase, the Flußgeschwin speed is reversed alternately in such a way that the coolant portion flowing along or in the unit ( 1 ) is stationary on average over the modulation over time. 17. The method according to any one of claims 12 to 16, characterized in that before or during the Cold start phase a predetermined amount of cooling warmed up medium and then in or on flows along the unit. 18. The method according to the preceding claim, because characterized in that the predetermined amount of cooling medium through a separate heating device device, for example a latency heat store, is warmed up.   19. The method according to any one of claims 12 to 18, characterized in that in the operating phase at least temporarily the flow velocity is alternately reduced and increased and / or the flow direction is alternately reversed. 20. The method according to any one of claims 12 to 19, characterized in that the frequency of the Mo dulation and / or the amplitude of the modulation, for example by a time program and / or a temperature sensor in / on the unit and / or in / on the cooling medium. 21. Use of a device according to one of the An claims 1 to 11 and / or a method one of claims 12 to 20 during the cold start phase and / or during the operating phase for cooling an internal combustion engine, ei ner fuel cell and / or a transmission as Heat generating device.