Vehicle cooling system and corresponding operating method

A vehicle cooling system may include a cooling circuit for cooling at least one main component of a vehicle. The cooling circuit may include at least one cooler through which cooling air is flowable and at least two fan chambers adjoined to an outlet side of the at least one cooler. The at least two fan chambers may each include a respective fan arranged therein, a respective main outlet and a respective ancillary outlet. The vehicle cooling system may also include at least one waste air channel that may be connected to the respective ancillary outlets of the at least two fan chambers. The vehicle cooling system may further include at least one control device configured to control a cross-section of each of the respective ancillary outlets and to enable operation of the vehicle cooling system in a normal operating state and in at least two emergency operating states.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Patent Application No. DE 10 2014 221 143.3, filed on Oct. 17, 2014, and International Patent Application No. PCT/EP2015/070709, filed on Sep. 10, 2015, both of which are hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a vehicle cooling system, in particular for rail vehicles, preferably in the form of an underfloor cooling system.

BACKGROUND

Vehicle cooling systems are used in electrically driven rail vehicles, so-called railcars, for cooling main components such as, for example a power electronics and an electric motor. For this purpose the vehicle cooling system can have a cooling circuit in which a liquid coolant circulates and in which the main components are incorporated in a heat-transmitting manner. In addition, a cooling means is incorporated in this circuit, through which cooling air can flow in order to deliver the heat taken up by the coolant to the cooling air. Furthermore, it is usual to use the waste air of the cooling means for cooling ancillary components of the vehicle such as, for example, choke coils, auxiliary transformers, auxiliary motors and switchgear cabinets.

Known from DE 196 32 053 C2 is a vehicle cooling system which has a cooling means of a cooling circuit for cooling a main component of the vehicle, wherein cooling air can flow through the cooling means. The known cooling system additionally has a supply chamber for supplying cooling air to an inlet side of the cooling means. Furthermore, a fan chamber is provided which is connected to an outlet side of the cooling means, in which a fan is arranged and which has a main outlet for cooling air and an ancillary outlet for cooling air. Whereas the main outlet leads to the surroundings of the vehicle, the ancillary outlet is connected to a waste air channel in which an ancillary component of the vehicle is arranged and which has a waste air outlet for cooling air which also leads to the surroundings of the vehicle.

In order in the event of a failure of the fan to be able to nevertheless ensure a sufficient cooling for the respective main component and in particular for the respective ancillary component, it is fundamentally possible to design the vehicle cooling system to be redundant with respect to the fan so that at least two fans are provided. In this case, it can be expedient to arrange the two fans in separate fan chambers which are each connected to the outlet side of the cooling means but have separate main outlets. The two fan chambers are then connected via separate ancillary outlets to the waste air channel. With the aid of a control device, it is then fundamentally possible to open both ancillary outlets for normal operation so that both fans convey cooling air on the one hand to the respective main outlet and on the other hand through the waste air channel to the respective ancillary component and through the waste air outlet. If one of the fans now fails, in an emergency operation with the aid of the control device, the ancillary outlet assigned to the switched-off fan can now be closed so that the remaining switched-on fan conveys cooling air on the one hand through the appurtenant main outlet and on the other hand through the appurtenant ancillary outlet and through the waste air channel to the respective ancillary component and through the waste air outlet. A problem with such a configuration is the fact that the division of the cooling air conveyed by the respective fan to the appurtenant main outlet on the one hand and to the appurtenant opened ancillary outlet on the other hand is only controlled by the different flow resistances. In order to now be able to convey sufficient cooling air through the significantly longer flow path from the respective fan through the appurtenant ancillary outlet, through the waste air channel in which flow takes place through and/or around the respective ancillary component, and through the waste air outlet, the cross-section of the appurtenant main outlet through which flow can take place must have correspondingly small dimension in order to produce a corresponding counter-pressure here. As a result, however the quantity of air flowing through the cooling means is ultimately reduced which reduces the cooling capacity of the cooling means or the appurtenant cooling circuit.

SUMMARY

The present invention is concerned with the problem of provided an improved embodiment for such a vehicle cooling system comprising a plurality of fan chambers and for an appurtenant operating method, which is characterized in particular by an improved cooling capacity.

This problem is solved according to the invention by the subject matters of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

The invention is based on the general idea in a vehicle cooling system comprising at least two fans downstream of a cooling means, for a normal operating state in which both fans are switched on, of only conveying cooling air through the waste air channel with the air of the one or first fan whilst with the other or second fan cooling air is not conveyed through the waste air channel but substantially only through the appurtenant main outlet. A main outlet assigned to the first fan is hereinafter designated as first main outlet whereas the main outlet assigned to the second fan is hereinafter designated as second main outlet. Since in the normal operating state, the second fan is therefore not required in order to convey cooling air through the waste air channel, the second main outlet can have significantly larger dimensions with regard to the cross-section through which cooling air can flow than the first main outlet assigned to the first fan. Thus, it is possible by means of a comparatively simple measure which is inexpensive to implement, to increase the cooling capacity of the vehicle cooling system at least for the normal operating state which represents the overwhelming majority of all the operating states of the vehicle cooling system. As a result of the larger second main outlet, the entire air flow conveyed by the second fan can be removed at reduced counterpressure so that ultimately more cooling air can be extracted by the cooling means. Accordingly, the cooling capacity of the cooling means and the associated cooling circuit is improved without the electrical power of the second fan needing to be increased for this purpose.

If the first fan now fails, the vehicle cooling system presented here can be operated in a first emergency operating state in which the second fan is now used to convey cooling air through the waste air channel. Since the second main outlet is larger than the first main outlet, the air flow conveyed through the waste air channel in the first emergency operating state is accordingly lower than during the normal operating state if the first fan and the second fan have the same power. The reduced cooling capacity for the respective ancillary component is however acceptable for the first emergency operating state since on the one hand only ancillary components are involved and since on the other hand the first emergency operating state only occurs rarely and in addition only comparatively briefly.

If on the other hand the second fan fails, in a second emergency operating state cooling air is only sucked in through the cooling means with the aid of the first fan but is still divided between the first main outlet and the waste air channel as in the normal operating state. Thus, substantially the same cooling capacity is available for the respective ancillary component.

The solution according to the invention is of particular importance since the performance of the vehicle cooling system can be improved merely by a changed control of the air flows and by an enlarged second main outlet. In particular, it is not necessary to change the cooling means and/or the fan for this increase in capacity.

According to an advantageous embodiment, the control device can comprise at least one adjustable actuator for controlling the ancillary outlets which is adjustable in a pressure-controlled manner and in addition passively depending on the pressure difference between the waste air channel and the fan chambers. In other words, no separate actuating drive is required for adjustment of the actuator. On the contrary, the adjustment of the actuator is made by the pressure differences acting thereon. For example, for the normal operating state as a result of the enlarged second main outlet, the pressure in the second fan chamber can be lowered so far that the actuator automatically adopts a position in which it opens the first ancillary outlet and closes the second ancillary outlet. The actuator automatically adopts this same position when the second fan fails in the second emergency operating state so that in the second fan chamber substantially ambient pressure or even a negative pressure below ambient pressure prevails. If on the other hand, the first fan fails in the first emergency operating state, the pressure in the first fan chamber falls to ambient pressure or below, with the result that the pressure ratios force the actuator to adopt a different position in which it closes the first ancillary outlet and opens the second ancillary outlet. Crucial for the passively adjustable actuator is the dimensioning of the cross-section of the second main outlet through which cooling air can flow in relation to the cross-section of the first main outlet through which cooling air can flow taking into account the flow resistance of the waste air channel. Accordingly, for the passively operating actuator, the flow resistances of the first main outlet, the second main outlet and waste air channel including the flow through or flow around the respective ancillary component as well as the flow resistance of the waste air outlet are matched to one another in such a manner that in the normal operating state a lower pressure prevails in the second fan chamber than in the second fan chamber and in the inlet region of the waste air channel.

According to another embodiment, the cross-section of the second main outlet through which cooling air can flow can be at least twice as large as the cross-section of the first main outlet through which cooling air can flow. With this dimensioning, in particular the previously explained passive control device can be achieved.

In another embodiment, the cross-section of the first main outlet through which cooling air can flow, the cross-section of the first ancillary outlet through which cooling air can flow, and the first fan can be matched to one another so that in the normal operating state and in the second emergency operating state cooling air driven by the first fan also flows through the first main outlet.

Additionally or alternatively it can be provided that the cross-section of the second main outlet through which cooling air can flow, the cross-section of the second ancillary outlet through which cooling air can flow, and the second fan are matched to one another so that in the first emergency operating state, cooling air driven by the second fan also flows through the second main outlet.

Particularly advantageous is an embodiment in which a housing is provided which contains the cooling means, the fan chambers and at least one inlet section of the waste air channel. By this means a particularly compact design can be achieved which on the one hand enables a pre-assembly of the vehicle cooling system and on the other hand simplifies its integration into a vehicle.

According to an advantageous further development, the respective fan can have a fan wheel arranged in the respective fan chamber and a fan motor arranged in a motor compartment for driving the fan wheel. As a result of this design, the fan motor can be comparatively well protected from impurities which can be entrained in the cooling air flow. Expediently here the respective motor compartment is sealed with respect to the respective fan chamber and with respect to the waste air channel so that the respective motor compartment does not have cooling air flowing through it. Expediently the respective motor compartment is also arranged in the aforesaid housing. Alternatively it can also be provided that to also arrange the respective fan motor in the respective fan chamber. It can further be provided to cool the respective fan motor with the waste air flow regardless of whether it is also arranged in the respective fan chamber or in a separate motor compartment.

If two fan chambers and two motor compartments are provided, the waste air channel can run through between the two motor compartments, resulting in a particularly compact, in particular flat design. Preferably the vehicle cooling system is an underfloor cooling system for a rail vehicle. In the installed state of the vehicle cooling system the main outlets and the respective waste air outlet are then open downwards. If the rail vehicle is standing or travelling correctly on rails, the main outlets and the respective waste air outlet are thus open towards a rail bed.

An operating method according to the invention for a vehicle cooling system with two or more fans is characterized by the previously indicated at least three different operating states, namely by the normal operating state, the first emergency operating state and the second emergency operating state. In the normal operating state both fans are switched on. In the first emergency operating state the first fan has failed or is switched off whilst the second fan is switched on. In the second emergency operating state on the other hand, the first fan is switched on whilst the second fan has failed or is switched off. During the normal operating state in the operating method according to the invention cooling air is only guided with the aid of the first fan to at least one of the ancillary components of the vehicle to be cooled whereas with the aid of the second fan, cooling air is only guided, bypassing the respective ancillary component into the surroundings or through the appurtenant second main outlet, In the first emergency operating state on the other hand, the second fan is used to guide cooling air to the respective ancillary component. In the second emergency operating state the first fan is used to guide cooling air to the respective ancillary component.

Preferably the operating method also operates with a pressure-controlled passive control device in order to control air flows inside the cooling system.

Further important features and advantages of the invention are obtained from the subclaims, from the drawings and from the appurtenant description of the figures with reference to the drawings.

It is understood that the features mentioned previously and to be explained further hereinafter can be used not only in the respectively given combination but also in other combinations or alone without departing from the scope of the present invention.

Preferred exemplary embodiments of the invention are presented in the drawings and are explained in detail in the following description, where the same reference numbers relate to the same or similar or functionally the same components.

DETAILED DESCRIPTION

According toFIGS. 1-3a vehicle cooling system1which preferably comprises an underfloor cooling system of a rail vehicle comprises at least one cooling means2which is incorporated in a cooling circuit3in which a preferably liquid coolant circulates and which serves for cooling at least one main component32of the vehicle which is only shown here symbolically. The main component32is for example a power electronic unit or an electric drive motor of the vehicle. The cooling circuit3contains a pump33for driving the coolant. The cooling means2can have cooling air4flowing through it according to arrows. The supply of cooling air4to an inlet side5of the cooling means2is made through a feed chamber6which is accordingly located upstream of the cooling device2.

The vehicle cooling system1additionally comprises a plurality of fan chambers, namely a first fan chamber7and a second fan chamber8. In the examples shown precisely two fan chambers7,8are provided. It is clear that in another embodiment three or more fan chambers7,8can also be provided. The respective fan chamber7,8is in each case fluidically connected to an outlet side9of the cooling means2so that the cooling air4can enter into the fan chambers7,8from the cooling means2. In each case one fan10,11is located in the respective fan chamber7,8. In this case, a first fan10is arranged in the first fan chamber7whilst a second fan11is arranged in the second fan chamber8. Both fan chambers7,8each have a main outlet12,13for cooling air4and in each case one ancillary outlet14,15for cooling air4. In this case, a first main outlet12and a first ancillary outlet14are assigned to the first fan chamber7whilst a second main outlet13and a second ancillary outlet15are assigned to the second fan chamber8.

The vehicle cooling system1further comprises a waste air channel16in which at least one ancillary component17of the vehicle is arranged. The respective ancillary component17can, for example, be an electric choke coil or an auxiliary transformer or an electric auxiliary motor or an electric switch cabinet. The arrangement of the respective ancillary component17in the waste air channel16is made in such a manner that the respective ancillary component17can have cooling air4flowing around and/or flowing through it so that the respective ancillary component17can be cooled with the aid of the cooling air4. An inlet section18of the waste air channel16is fluidically connected to the first ancillary outlet14and to the second ancillary outlet15so that cooling air4can flow into the waste air channel16from the fan chambers7,8. The waste air channel16has in an outlet section19at least one waste air outlet20through which the cooling air4can flow out. In the example, the respective ancillary component17is arranged between the inlet section18and the outlet section19in the waste air channel16.

The main outlets12,13and the waste air outlet20are preferably each open to the surroundings21of the vehicle cooling system1or the vehicle fitted therewith so that cooling air4can exit through the respective outlet12,13,20into the surroundings21. In the installed state of the vehicle cooling system1, the main outlets12,13and the waste air outlet20are each open downwards to the surroundings21.

The vehicle cooling system1is additionally fitted with a control device22which is used for controlling the ancillary outlets14,15with regard to the cross-section through which flow can take place. In the example, the control device22is a flap-shaped actuator23which is pivotable about a pivot axis24between a first switching position S1shown inFIGS. 1band 3band a second switching position S2shown inFIG. 2b. In the first switching position S1the actuator23opens the first ancillary outlet14whilst it blocks the second ancillary outlet15. In the second switching position S2the actuator23opens the second ancillary outlet15whilst it blocks the first ancillary outlet14. Corresponding to this, two switching states can thus be set with the aid of the control device22which correspond with the switching position S1and S2of the actuator23and accordingly can also be designated with S1or S2. In the first switching state S1of the control device22, the first ancillary outlet14is accordingly opened whereas the second ancillary outlet15is closed. In the second switching state S2on the other hand the first ancillary outlet14is closed whilst the second ancillary outlet15is open.

As can be deduced fromFIGS. 1b, 2band 3b, the second main outlet13has larger dimensions than the first main outlet12. Accordingly the second main outlet13has a larger cross-section through which cooling air4can flow than the first main outlet12. In the diagrams show the cross-section of the second main outlet13through which flow can take place is at least twice as large as the cross-section of the first main outlet12through which flow can take place.

The control device22is now configured so that it can implement at least three different operating states for the vehicle cooling system1, namely a normal operating state RZ shown inFIGS. 1aand 1b, a first emergency operating state NZ1shown inFIGS. 2aand 2band a second emergency operating state NZ2shown inFIGS. 3aand3b.

In the normal operating state RZ according toFIG. 1b, the first fan10and the second fan11are switched on so that they each convey fresh air4. In the normal operating state RZ the control device22brings about an opening of the first ancillary outlet14and a closing of the second ancillary outlet15. Accordingly the control device22adopts its first switching state S1. Consequently cooling air4driven by the first fan10can flow from the first fan chamber7through the first ancillary outlet14, through the waste air channel16and through the waste air outlet20. In so doing, flow takes place around or through the respective ancillary component17whereby this is accordingly cooled. The cooling air4driven by the second fan11on the other hand flows, bypassing the waste air channel16, from the second fan chamber8through the second main outlet13. Since the comparatively large second main outlet13only has a relatively small flow resistance, a comparatively large cooling air flow can be conveyed with the aid of the second fan11which brings about an efficient cooling of the cooling means2and therefore of the coolant circulating in the cooling circuit3.

In the first emergency operating state NZ1according toFIG. 2b, the first fan10is switched off whereas the second fan11is switched on. In the first emergency operating state NZ1the control device22brings about a closing of the first ancillary outlet14and an opening of the second ancillary outlet15. Accordingly the control device22adopts its second switching state S2or the actuator23is adjusted into the second switching position S2. Consequently, the cooling air4driven by the second fan11flows from the second fan chamber8through the second ancillary outlet15, through the waste air channel16and through the respective waste air outlet20. In so doing, flow takes place through or around the respective ancillary component17arranged in the waste air channel16. Since the second main outlet13is comparatively large and accordingly has a comparatively low flow resistance, in this first emergency operating state NZ1the flow of cooling air4through the waste air channel16is significantly reduced compared with the normal operating state RZ. However, this can be accepted for the comparatively short-term emergency operation.

In the second emergency operating state according toFIG. 3b, the first fan10is switched on whilst the second fan11is switched off. In the second emergency operating state NZ2the control device22again adopts its first switching state S1. Accordingly the actuator23is again adjusted into its first switching position S1. Consequently the ancillary outlet14is again opened whilst the second ancillary outlet15is closed again. The first fan10now drives cooling air4again so that this flows from the first fan chamber7through the first ancillary outlet14, through the waste air channel16and through the waste air outlet20. In this case, a cooling of the respective ancillary component17takes place as it were as in the normal operating state RZ.

Expediently the control device22operates free from external energy, namely pressure-controlled. To this end, the actuator23is passively adjustable, namely depending on the pressure differences acting thereon. In the normal operating state RZ according toFIG. 1band in the second emergency operating state NZ2according toFIG. 3b, the pressure in the first fan chamber7and in the inlet section18of the waste air channel16is higher than in the second fan chamber8with the result that the actuator22automatically adopts the first switching position S1for closing the second ancillary outlet15and for opening the first ancillary outlet14. In the first emergency operating state NZ1according toFIG. 2bon the other hand, the pressure in the second fan chamber8and in the inlet section18of the waste air channel16is higher than in the first fan chamber7, with the result that the actuator23is automatically adjusted into its second switching position S2in which it closes the first ancillary outlet14and releases the second ancillary outlet15.

The first main outlet12and the second main outlet13are uncontrolled, i.e. permanently open. However they are matched with regard to the cross-section through which flow can take place to the capacity of the respective fan10,11and to the flow resistance of the waste air channel16so that in each case a flow of cooling air takes place through the respective main outlet12,13when the appurtenant fan10,11is switched on.

As can be deduced fromFIGS. 1 to 3, the vehicle cooling system1also has a housing25which contains the cooling means2, the fan chambers7,8and at least one inlet section18of the waste air channel16. In this case, the fan chambers7,8are arranged horizontally adjacent to one another so that in the normal operating state RZ parallel flow takes place through these. The fans10,11each comprise a fan wheel, namely a first fan wheel26and a second fan wheel27as well as a fan motor, namely a first fan motor28and a second fan motor29. The first fan motor28is in this case arranged in a first motor compartment30and is used to drive the first fan wheel26. The second fan motor29is used to drive the second fan wheel27and is arranged in a second motor compartment31. The motor compartments30,31are fluidically separated from the fan chambers7,8and from the waste air channel16so that no cooling air4flows through them. Furthermore the motor compartments30,31are preferably also accommodated in the housing25.

A method for operating the vehicle cooling system1can be summarized as follows:

In the normal operating state RZ according toFIGS. 1aand 1b, the first fan10and the second fan11are switched on so that only cooling air4driven by the first fan10is guided from the cooling means2to the respective ancillary component17and then through the waste air outlet4. Cooling air4driven by the second fan11is in this case not guided to the respective ancillary component17but only through the second main outlet13.

According toFIGS. 2aand 2b, in the first emergency operating state NZ1the first fan10is switched off and the second fan11is switched on where cooling air4driven by the second fan11is guided firstly from the cooling means2to the respective ancillary component17and then through the waste air outlet20.

According toFIGS. 3aand 3b, in the second emergency operating state NZ2the first fan10is switched on and the second fan11is switched off whereby only cooling air4driven by the first fan10is guided from the cooling means2to the respective ancillary component17and then through the waste air outlet20.

Since in the vehicle cooling system1presented here, the control device22operates in a pressure-controlled manner, the switching on or switching off of the respective fan10,11brings about the pressure difference required at the actuator23for setting the respectively desired switching position S1or S2of the actuator23or the respective switching state S1or S2of the control device22. Thus, in particular an electric-motor drive or the like for the actuator23can be dispensed with.