DE102007058575A1 - Motor vehicle i.e. road vehicle, has feeder line supplying cooling system with compressed air, and control unit controlling supply of cooling system with compressed air depending on signal delivered by sensor - Google Patents

Abstract

The vehicle has an engine with a liquid cooling system (2) for cooling the engine. A coolant of the liquid cooling system stays under a preset high pressure during operation of the engine. A sensor (14) detects an operating condition of the engine and outputs a characteristic signal of an operating condition. A feeder line (12) is provided between a compressed air system (10) and the cooling system and supplies the cooling system with compressed air. A control unit (30) controls the supply of the cooling system with compressed air depending on the signal delivered by the sensor. An independent claim is also included for a method for operating a motor vehicle engine.

Description

The The present invention relates to a motor vehicle and more particularly a road vehicle, which at least also driven by an internal combustion engine becomes. Such engines usually have Liquid cooling systems, being a cooling liquid in a cycle is going to be the warming Cool parts of the engine.

In such vehicle cooling systems is used to avoid boiling and cavitation of the usual liquid refrigerant an overpressure needed. This overpressure is due to the warming of the coolant generated during operation of the vehicle. It determines the Size of one Compensation volume and the coolant temperature the self-adjusting overpressure. When starting the engine, the coolant is usually cold and therefore is not over pressure available, which is why, under certain circumstances Cavitation may occur on the water pump suction side. With increasing warming of the coolant this expands, creating an overpressure in the system, which shuts off the cavitation phenomenon at a certain level, since from this pressure no drop below the vapor pressure occurs more.

In order to exists in the prior art, the problem that not always sufficient pressure in the cooling system to disposal is, but this of the coolant temperature dependent is.

Becomes continue to be turned off after operation of the engine, within locally hot parts of the engine and it can happen because of the missing ones flow to a boil of the coolant come. It displaces the resulting vapor bubble coolant in the expansion tank. If the compensating volume of the expansion tank is too small, can it in this way to coolant loss come. Another problem in the prior art is therefore therein to see that it is at engine standstill to a boiling of the coolant can come.

Farther In motor vehicles usually pressure relief valves used. these can by dirt particles, for example by the ventilation when exceeded the opening pressure Ingress lead to a drop in tightness. Also, it is possible that it comes to leaks as a result of aging of the seals, It should be noted here that the seals are made of elastomers are made.

at Present such leaking pressure relief valves It can happen that there is no or only too little overpressure build up, so that cavitation can take place permanently, which in turn to reduced water pump delivery and to coolant loss leads. Also, it can permanently lead to coolant loss when hot off there is no sufficient overpressure is available to raise the boiling temperature.

Of the The present invention is therefore based on the object, a device available too provide, on the one hand, a sufficient overpressure in the cooling system independently from the coolant temperature gewährleitstet on the other hand, a sufficient or increased pressure in a motor stall to disposal to suppress boiling and finally also a tracking of a through a leak lost overpressure allows.

More accurate said to be an apparatus and method for controlling overpressure in cooling systems to disposal which are used to avoid boiling and cavitation so designed is that in the operating conditions occurring during vehicle operation of the respectively required overpressure is set.

This is inventively achieved the subject matter of claim 1. Advantageous embodiments and further developments are the subject of the dependent claims.

One Motor vehicle according to the invention has an engine, wherein the engine is a liquid cooling system for cooling the Motors and the coolant this liquid cooling system while the operation of the engine under a predetermined pressure stands. In addition, the motor vehicle and preferably the motor at least a sensor, the at least one operating condition of the engine recorded and the one for outputs this signal characteristic signal.

According to the invention the motor vehicle a compressed air system on and between this compressed air system and the cooling system a connecting line is provided, which the cooling system at least temporarily supplied with compressed air. Furthermore, a Steuerungsein direction provided, which supplies the cooling system with compressed air in dependence controls the signal output from the sensor.

Thus, the invention proposes to achieve by supplying compressed air into the cooling system, that the period of insufficient overpressure in the cooling system is shortened or eliminated and in this way the period is shortened, can occur in the cavitation on the water pump suction side. More specifically, by this supply of compressed air in the cooling system for a üb acceptable engine operation set acceptable pressure.

By The use of the sensor ensures that the compressed air only in certain operating conditions of the vehicle, for example, at a certain temperature of Coolant, a certain pressure of the same or after switching off is supplied.

The today usually used cooling systems are designed so that the overpressure in the cooling systems by means of a pressure relief valve to 0.6-1.1 is limited. With the mentioned additional generated by the water pump dynamic pressure arise locally in Cooling system overpressures, up the respective components such as the water cooler, the heating heat exchanger and the tubes designed in terms of strength become. The load capacity of these components limited at the same time the usable cooling water overpressure.

At the hot soak an engine is usually eliminated the coolant circulation. This also eliminates the dynamic overpressure through the water pump so that only a cooling system overpressure between 0.6 and 1.1 bar is available, so, as mentioned above, on hot Make boiling occurs. To suppress this boiling is sure high overpressure - considerably more than 1 bar - required or a correspondingly large Compensation volume in which the displaced by the steam bubble coolant is caught. Thus, by the present invention also be achieved that reduces this compensation volume or a existing equalization volume in the cooling system with higher coolant temperatures is operated.

Preferably is a pressure reduction device between the compressed air system and the cooling system provided by the compressed air system to the cooling system decreasing pressure decreases.

As mentioned, A connection is made in the engine cooling system from the vehicle compressed air system depending on the operating condition needs-based overpressure available put. As the pressure level of this compressed air system usually is above 8 bar, it is too high for the coolant circuit so the Pressure is lowered by the pressure reducing device.

at a further advantageous embodiment, the liquid cooling system an equalization container on and the connection line opens in this expansion tank. The expansion tank is particularly suitable for reducing overpressure, since, as mentioned above, a Equalizing volume, in which directly the pressure can be fed.

at In a further advantageous embodiment, the pressure reduction device has at least a controllable valve on. More precisely, it can be about act a pressure control valve, which adjusts depending on the operating condition becomes.

at A further advantageous embodiment is a control device provided, which supply the cooling system with compressed air in dependence of an operating state of the engine controls. It can be in these operating conditions for example, an on or off state d. H. the decision on whether the engine is running or not, act. Also can In an operating condition, this is a cooling water temperature or a time interval after stopping the engine. Furthermore comes as operating condition and a pressure of the coolant in the cooling system into consideration.

at In another advantageous embodiment, the pressure reduction device has two Pressure reducing valves, which preferably each have a controllable Valve is connected upstream. More precisely, it is possible to do this two pressure reducing valves upstream a solenoid valve, wherein These pressure reducing valves depending on the operating condition with this each can be switched to a solenoid valve. Preferably, in this case these two pressure reducing valves on different working pressures. Thus, the one pressure reducing valve can have a working pressure between 0.6 and 1.1 bar and the second pressure reducing valve has a working pressure between 1 and 2 bar. Thus, the first mentioned pressure reducing valve in the normal Used vehicle operation and the second pressure reducing valve, for example after stopping the engine to prevent boiling.

Preferably the pressure reduction device has a pressure regulating valve which the pressure in dependence governed by an operating condition of the engine. This can at both embodiments the two different pressure levels required in the operating state be achieved in different ways.

Advantageous For example, the motor vehicle has a plurality of sensors which indicate operating states of the engine capture the sensors are designed so that they are characteristic of the operating conditions Forward signals to the controller. In these states can it is, as mentioned above, to operate temperatures, times and the like.

Furthermore, the control device particularly preferably has a process device, which logically links the characteristic signals. It is thus possible to switch a specific valve only if, on the one hand, no more than 15 minutes have passed after the engine has been switched off and, on the other hand, the coolant temperature is above 100 °. Also, corresponding logical OR operations would be conceivable.

The The present invention is further directed to a method of operation directed a motor vehicle engine and in particular an internal combustion engine. In this case, this motor vehicle engine with a liquid cooling system chilled and the coolant this liquid cooling system stands while the operation of the engine under a predetermined pressure. According to the invention by means of a compressed air system of the motor vehicle and the liquid cooling system arranged connecting line the liquid cooling system temporarily with compressed air supplied and this supply of compressed air is dependent from an operating condition of the engine.

Especially is the compressed air system the compressed air system, which for the brake system of the vehicle is used. The one in this compressed air system existing pressure usually exists even after the engine is switched off and can therefore be used be to the cooling system to supply with compressed air. It is pointed out that instead from compressed air also other gaseous Media can be used.

Preferably becomes the liquid cooling system at least temporarily during a standstill of the motor vehicle engine supplied with compressed air. In this method is achieved that the formation of cavities after the shutdown of the engine can be counteracted.

at Another preferred method is by means of at least one Sensors one for an operating condition of the engine characteristic signal measured and the liquid cooling system becomes dependent supplied with compressed air by this signal. This can be for example to act a signal indicating whether the engine is running or not. However, the operating state can also be a temperature of the coolant act.

Further Advantages and embodiments emerge from the attached Drawings:

In this demonstrate:

1 a schematic representation of a device according to the invention in a first embodiment; and

2 a schematic representation of a device according to the invention in a further embodiment.

In 1 the reference number refers 2 on a partially illustrated liquid Kühlystem. More precisely, here is a surge tank 4 for this cooling system 2 shown. In this expansion tank 4 there is coolant 5 , which reaches here to a level N level. If, as mentioned above, form vapor bubbles within the cooling circuit, the space lying above the level N level can 7 be used to accommodate this expansion. However, if the level rises further than the room 7 allows, coolant is via an outlet 8th leak out and get lost in this way for the cooling circuit. The reference number 6 refers to a pipe that opens into the cooling circuit.

The reference number 10 refers generally to a compressed air system of the vehicle. In this case, the reference numeral 11 a compressed air tank for the vehicle. About a connecting line according to the invention 12 stands this compressed air system 10 with the liquid cooling system 2 in connection with, as mentioned above, this connection line 12 preferably in the expansion tank 4 the cooling system and more preferably in the area 7 of the expansion tank 4 , ie the area above the liquid level N opens.

That way the pressure in the room can be reduced 7 and thus the pressure on the coolant 5 be increased if necessary so that, for example, the occurrence of vapor bubbles can be at least partially compensated.

The reference number 20 refers to a pressure control, which in the reservoir 4 reaching pressure of the compressed air controls. More specifically, this is a pressure reducer 20 , which from the compressed air system 10 lowers escaping pressure.

At the in 1 embodiment shown, this pressure reducing device 20 two solenoid valves 22 and 23 on and these solenoid valves 22 . 23 downstream pressure reducing valves 24 and 25 , The two solenoid valves 22 and 23 be via a control device 30 controlled and in response to the signals from various sensors 14 ,

The pressure reducing valve 24 reduces the pressure of the compressed air system 10 originating pressure to a pressure in the range of 0.6-1.1 bar. The pressure reducing valve 25 reduces this pressure to one Pressure between 1 and 2 bar.

Depending on the sensors 14 Measured signals can either be access to the pressure reducing valve 24 or access to the pressure reducing valve 25 released or both accesses are blocked or opened.

For example, if it is detected by the sensors that the engine is running, it is possible to use the solenoid valve 22 to open and thus a pressure between 0.6 and 1.1 bar on the expansion tank 4 and thus allow the cooling circuit. If the engine is in another operating state and the temperature of the cooling water is above a certain value, for example above 100 °, the first solenoid valve 22 closed, the solenoid valve 23 opened and over the pressure reducing valve 25 a pressure of 1,1-2 bar allowed on the cooling circuit.

Furthermore, it is possible to determine the time after which the engine has been switched off and, for example, to allow a pressure between 1.1 and 2 bar in a period of 15 minutes, by the solenoid valve 23 opened and the solenoid valve 22 is closed.

2 shows a further embodiment of an arrangement according to the invention. Instead of the arrangement shown above with the two solenoid valves and the pressure reducing valves here is a pressure control valve 26 provided, which in turn of the control device 30 is controlled. The of this pressure control valve 26 The pressure released can in turn depend on the signals from the sensors 14 as described above.

All Features disclosed in the application documents are considered to be essential to the invention as long as they are individually or in combination with respect to State of the art are new.

2

Vehicle Cooling System

4

surge tank

5

coolant

6

management

7

room

8th

exit

10

Compressed air system

11

Air receiver

12

connecting line

14

sensors

20

pressure control

22 23

magnetic valve

24 25

Pressure Reducing Valves

26

Pressure control valve

30

control device

N

filling level

Claims (12)

Motor vehicle with an engine, the engine having a liquid cooling system ( 2 ) for cooling the engine and the cooling liquid of this liquid cooling system ( 2 ) is under a predetermined pressure during operation of the engine, and with at least one sensor which detects at least one operating state of the engine and which outputs a characteristic of this operating condition signal. characterized in that the motor vehicle is a compressed air system ( 10 ), and between the compressed air system ( 10 ) and the cooling system a connecting line ( 12 ) is provided, which the cooling system ( 2 ) at least temporarily supplied with compressed air, wherein a control device ( 30 ) is provided which the supply of the cooling system ( 2 ) with compressed air as a function of that of the sensor ( 14 ) signal is output. Motor vehicle according to claim 1, characterized in that between the compressed air system ( 10 ) and the cooling system ( 2 ) a pressure reducing device ( 20 ), which of the compressed air system ( 10 ) to the cooling system ( 2 ) decreases pressure. Motor vehicle according to at least one of the preceding claims, characterized in that the liquid cooling system ( 2 ) a surge tank ( 4 ) and the connecting line ( 12 ) opens into this expansion tank. Motor vehicle according to at least one of the preceding claims, characterized in that the pressure reducing device ( 20 ) at least one controllable valve ( 22 ) having. Motor vehicle according to at least one of the preceding claims, characterized in that a control device ( 30 ) is provided, which controls the supply of the cooling system with compressed air in response to an operating condition of the engine. Motor vehicle according to at least one of the preceding claims 4-5, characterized in that the pressure reducing device ( 20 ) two pressure reducing valves ( 24 . 25 ), each having a controllable valve ( 22 . 23 ) is connected upstream. Motor vehicle according to at least one of the preceding claims 4-5, characterized in that the pressure reducing device ( 20 ) a pressure regulating valve ( 26 ), which regulates the pressure in response to an operating condition of the engine. Motor vehicle according to at least one of the preceding claims 5-7, characterized in that the motor vehicle a plurality of sensors ( 14 ), which detect operating states of the engine, wherein the sensors ( 14 ) are designed in such a way that they send signals which are characteristic of the operating states to the control device ( 30 ) hand off. Motor vehicle according to claim 8, characterized in that the control device ( 30 ) a processor device ( 32 ), which logically combines the characteristic signals. Method for operating an automobile engine, wherein the motor vehicle engine is provided with a fluid cooling system ( 2 ) and the cooling liquid of this liquid cooling system ( 2 ) is under a predetermined pressure during operation of the engine, characterized in that by means of an intermediate pressure air system ( 10 ) of the motor vehicle and the liquid cooling system ( 2 ) arranged connecting line ( 12 ) the liquid cooling system ( 2 ) is temporarily supplied with compressed air and this supply of compressed air in response to an operating condition of the engine takes place. Method according to claim 10, characterized in that the liquid cooling system ( 2 ) is supplied at least temporarily during a standstill of the motor vehicle engine with compressed air. Method according to at least one of the preceding claims 10-11, characterized in that by means of at least one sensor a characteristic of an operating condition of the engine signal is measured and the liquid cooling system ( 2 ) is supplied with compressed air in response to this signal.