DE102013002847A1 - Battery arrangement for e.g. mild hybrid vehicle, has cooling unit for cooling phase change material, where cooling unit is constructed as evaporator of air conditioner, which is acted upon with refrigerants relaxed at expander unit - Google Patents

Abstract

The arrangement (10) has a set of battery cells (12) with a latent heat accumulator (28) comprising a phase change material (26) for cooling of the set of battery cells. A cooling unit is arranged for cooling the phase change material. The cooling unit is constructed as an evaporator (16) of an air conditioner, which is acted upon with refrigerants relaxed at an expander unit (14). The latent heat accumulator is in abutment with the evaporator. The latent heat accumulator is arranged with a bottom plate, which together with the battery cells form the arrangement. An independent claim is also included for a method for operating a battery arrangement.

Description

The invention relates to a battery arrangement for a vehicle, which comprises a plurality of battery cells. For cooling the battery cells, a latent heat storage is provided, which has a phase change material. A cooling device of the battery arrangement serves to cool the phase change material. Furthermore, the invention relates to a method for operating such a battery arrangement.

The DE 10 2007 050 812 A1 describes an electrochemical energy store with a plurality of battery cells, which are designed as lithium-ion batteries. For cooling the battery cells, a latent heat storage is provided, which contains a phase change material. The phase change material in turn can be tempered by means of tubes which are arranged in the phase change material and through which a coolant flows. The coolant is supplied by means of a pump to a heat exchanger, which can be acted upon by means of a fan with a cooling air flow.

A disadvantage here is the fact that not always sufficient cooling of the phase change material is possible.

Furthermore, battery arrangements are in the DE 10 2010 063 057 A1 , of the CN 187 03 47 A , of the DE 10 2010 005 097 A1 , of the DE 103 58 582 A1 and the DE 10 2011 106 690 A1 described, which have a plurality of battery cells, wherein for the cooling of the battery cells, a phase change material is used.

The DE 10 2007 010 750 B3 describes a single battery cell with means for heat dissipation from the battery cell.

From the motor vehicle industry, it is also known to provide for the battery of a hybrid vehicle, a cooling circuit with a coolant, which consists of air or a water-glycol mixture. This cooling circuit is connected via a heat exchanger in thermal communication with the refrigerant circuit of an air conditioner of the hybrid vehicle. About the operation of the air conditioner can be ensured so that waste heat of the battery cells is discharged indirectly to the refrigerant circuit. However, this is not sufficiently possible if a large air conditioning capacity of the air conditioning system for cooling the vehicle cabin, so the passenger compartment, to be provided.

Object of the present invention is to provide a battery assembly of the type mentioned above and a method for operating such a battery assembly, which or which allows improved cooling of the battery cells.

This object is achieved by a battery arrangement having the features of patent claim 1 and by a method having the features of patent claim 10. Advantageous embodiments with expedient developments of the invention are specified in the dependent claims.

According to the invention, the cooling device is designed as an evaporator of an air conditioning system, which can be acted upon by a refrigerant which has been expanded at an expansion device. By using the evaporator of the air conditioner for cooling the phase change material, a particularly extensive cooling of the phase change material can be ensured even at relatively high ambient temperature. If, on the other hand, the phase change material were cooled only by means of a cooling liquid, which heat is removed from a heat exchanger, it is not possible to ensure sufficient cooling of the phase change material, in particular no cooling below the temperature of the phase transition, at high outside temperatures.

In the present case, however, the evaporator ensures that the phase change material is cooled down so far that a phase transition takes place. Then it can be ensured that the battery cells do not exceed a critical upper limit of the temperature at a heat output of the battery cells by a new phase transition of the phase change material.

Such a case, in which a comparatively strong cooling capacity is required, may be present, for example, when at high outside temperature a previously parked vehicle is put into operation and when driving off the battery cells provide electrical energy for driving the vehicle. In such a case, namely, the cooling capacity of the air conditioning system provided for cooling the passenger compartment of the vehicle is not available for cooling the battery cells. However, the waste heat of the battery cells can be absorbed by the phase change material by a phase transition of the phase change material takes place.

Is then then again excess cooling capacity of the air conditioning ready, because the passenger compartment has already been cooled to a comfortable temperature, the cooling power can be used to cool the phase change material, which thereby again changes its state of aggregation. This also works with a particularly high outside temperature, with which a cooling the battery cells with a cooling liquid or cooling air would not be sufficiently accomplished.

A particularly good heat transfer from the phase change material to the evaporator can be achieved if, according to an advantageous embodiment of the invention, the latent heat accumulator is in contact with the evaporator.

It is furthermore preferred if a bottom plate of an assembly of the battery arrangement comprising the latent heat store and the battery cells is formed by the evaporator. Thus, a particularly compact design of the battery assembly can be achieved, and at the same time dissipate good heat from the battery cells.

As a further advantage, it has been shown that housing of the individual battery cells are peripherally circumferentially enclosed by the phase change material of the latent heat storage and a bottom surface of the housing of the respective battery cell with the phase change material in plant. Thus, a particularly good cooling of the battery cells can be achieved by means of a heat relatively poorly conducting phase change material.

In a further advantageous embodiment of the invention, the battery arrangement comprises a control device which serves to control a valve device. The valve device allows in an open position to flow through the evaporator with the refrigerant, and in a closed position of the valve device, the flow is prevented. Such a control device can be designed to be particularly simple, since it merely has to ensure that the evaporator is operated when the valve device is open or the evaporator is inactive when the valve device is closed. Such a clocked switching on and off of the evaporator by controlling the valve device can be particularly simple to implement control technology or control technology.

In this case, it has proven to be advantageous if the control device is designed to bring about the movement of the valve device into the open position and into the closed position as a function of a temperature of the battery cells. Thus, opening of the valve device and thus cooling of the phase change material caused by the pressurization of the evaporator with the expanded refrigerant can always be ensured when the temperature of the battery cells reaches a predetermined threshold value.

Additionally or alternatively, the control device may be designed to bring about the movement of the valve device into the open position or into the closed position as a function of a time span provided for a phase transition of the phase change material. For example, then the valve device can be moved into the open position, if it can be assumed that in the period of time a certain percentage of the phase change material has changed its state of aggregation.

This can happen, for example, when 80% to nearly 100%, in particular 90% to 95%, of the phase change material have completed the phase transition. If the valve device is then moved into the open position, it takes an equally long period of time to transfer the phase change material back into the previous state of aggregation, which is suitable for absorbing heat. If then the valve device is left in the open position, the temperature of the battery cells decreases. This can continue until the battery cells have reached a lower limit of the temperature.

It is furthermore advantageous if heat-conducting elements are connected to the evaporator, by means of which heat released during a phase transition of the phase-change material can be transferred to the evaporator. This takes into account the fact that phase change materials usually have a comparatively poor thermal conductivity. Nevertheless, a particularly good heat transfer from the phase change material to the evaporator can be ensured by the heat-conducting elements connected to the evaporator.

Such heat-conducting elements can be formed, for example, as a solid body made of a good heat-conducting material, for example of a metal or an alloy.

Preferably, the heat-conducting elements are arranged in respective intermediate spaces, which are formed between the individual battery cells. Then the heat can be removed particularly evenly from the phase change material.

Finally, it has proven to be advantageous if the heat-conducting elements are peripherally surrounded circumferentially by the phase change material of the latent heat storage. In that case, the heat released during the phase transition of the phase change material can be transmitted to the evaporator via the heat conducting elements in a particularly good way.

In the method according to the invention for operating a battery arrangement for a vehicle, of a plurality of battery cells of the Battery assembly releases heat. This heat is transferred to a phase change material of a latent heat storage. Subsequently, the phase change material is cooled by means of a cooling device again. This can be done in particular to effect a phase transition of the phase change material. As a cooling device, an evaporator of an air conditioner is used, which is acted upon for cooling the phase change material with a refrigerant which has been expanded at an expansion device.

With the expanded refrigerant, a particularly high cooling capacity can be provided via the evaporator, even if high outside temperatures are present. So it can be ensured that even at high outside temperatures efficient cooling of the battery cells is ensured.

The advantages and preferred embodiments described for the battery arrangement according to the invention also apply to the method according to the invention and vice versa.

The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or in the figures alone can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention.

Further advantages, features and details of the invention will become apparent from the claims, the following description of preferred embodiments and from the drawings. Showing:

1 a battery assembly in which a phase change material is cooled by means of an evaporator plate which is integrated into a refrigerant circuit of an air conditioner, wherein battery cells of the battery assembly are peripherally surrounded by the phase change material;

2 the temperature profile of the phase change material when supplying heat;

3 the clocked driving a valve upstream of the evaporator plate in dependence on the temperature of the battery cells and the phase transition of the phase change material; and

4 a battery assembly according to 1 , wherein between the individual battery cells in addition heat conducting plates are arranged, which are connected to the evaporator plate.

An in 1 schematically shown battery arrangement 10 can be used in particular in a micro hybrid vehicle or a mild hybrid vehicle. Here are battery cells 12 , which may be designed in particular as lithium-ion battery cells, such as when starting or when starting and accelerating the hybrid vehicle electrical energy ready. In such a boost process put the battery cells 12 Relatively much waste heat free. When braking, electrical energy is recovered and into the battery cells 12 brought in. Again, waste heat is released.

By frequent discharging and charging of the battery cells 12 With comparatively large electrical currents, there is thus a frequent release of waste heat from the battery cells 12 , The battery cells 12 However, they are relatively temperature sensitive, therefore, the battery assembly includes 10 a cooling system.

In the present case is for cooling the battery cells 12 a refrigerant circuit is provided which is part of an air conditioning system of the vehicle. Such a refrigerant circuit comprises a compressor (not shown), to which a condenser is connected downstream. In the condenser, the compressed refrigerant is liquefied. Subsequently, the liquefied refrigerant by means of an expansion device, for example in the form of an expansion valve shown here by way of example 14 relaxed and fed to an evaporator, which in the present case as an evaporator plate 16 is trained. In the evaporator plate 16 the expanded refrigerant evaporates while absorbing heat. Subsequently, the refrigerant is returned to the compressor.

In the present case, the air conditioning is used both for air conditioning of the passenger compartment and for dissipating heat from the battery cells 12 by means of the evaporator plate 16 , For cooling the passenger compartment, however, another (not shown) evaporator is provided in the refrigerant circuit of the air conditioner, on which the air to be introduced into the passenger compartment is cooled.

The evaporator plate 16 forms a bottom plate of a housing 18 in which the battery cells 12 are included. In intervals 20 between the individual battery cells 12 as well as in one area 22 between floor surfaces 24 of respective housings of the individual battery cells 12 and the evaporator plate 16 is a phase change material (PCM, phase change material) 26 , which can provide cooling power in particular by a phase transition, ie by changing its state of aggregation. The phase change material 26 belongs to one Latent heat storage 28 which is in the housing 18 the battery arrangement 10 is arranged.

The respective battery cells 12 can have an electrically insulating sheath, so that in the battery assembly 10 the phase change material 26 adjacent to these electrically insulating sheaths. When the battery cells 12 not already before their installation in the battery assembly 10 are provided with such cases, so may in the manufacture of the battery assembly 10 between the respective battery cells 12 and the phase change material 26 an electrically insulating separator can be arranged.

If the passenger compartment of the hybrid vehicle is to be primarily cooled, for example, because the vehicle was parked in the sun for a long time on a hot day, the cooling power available from the air conditioning system is initially used to cool the passenger compartment. To ensure this, a shut-off valve 30 closed, which in one to the evaporator plate 16 leading refrigerant line 32 of the refrigerant circuit is arranged. Then, the refrigerant flows exclusively to the other (not shown here) evaporator, at which the cooling of the passenger compartment air supplied takes place.

When the hybrid vehicle parked in the sun goes off, the battery cells set 12 this electrical energy ready. The resulting waste heat of a battery cells 12 comprehensive battery can now from the phase change material 26 be absorbed, in particular by the phase change material 26 changes its state of aggregation. The result of this is that the temperature of the battery does not rise above a critical upper limit, above which a control device, namely a so-called battery management controller, switches off the battery for safety reasons. The advantage in the hybrid vehicle by means of the battery cells 12 To provide electrical energy, so in the present case also remains in this situation.

Due to the fact that the phase change material 26 both in the interstices 20 between the battery cells 12 and surrounds this circumference circumferentially and also in the area 22 is provided, the phase change material 26 especially good the waste heat of the battery cells 12 take up. In addition, there are the battery cells 12 on the phase change material 26 on, which in turn with the evaporator plate 16 in attachment.

Thus, if during the boost process of the hybrid vehicle, so for example when driving off, the battery just no cooling power is provided by the air conditioning available, so the waste heat of the battery cells 12 through the phase change material 26 absorbed. The phase change material 26 namely has the property to keep the temperature during the phase transition almost constant despite the heat absorption.

This is based on 2 illustrated. Here is on an ordinate 34 the temperature T _{PCM of} the phase change material 26 plotted and on an abscissa 36 that of the phase change material 26 absorbed heat Q. A temperature-indicating curve 38 has a plateau accordingly 40 on, which is the constant temperature of the phase change material 26 despite the heat supply illustrated. By mixing the phase change material 26 With another material, such as water, a phase change point or phase change point (PCP) can be set so that the temperature of the battery does not exceed a critical upper limit during the boost process. In particular, it can be provided that the temperature of the battery cells 12 does not exceed 50 ° C.

After the passenger compartment has been cooled to a comfortable temperature, the air conditioning system can now again not required for the cooling of the passenger compartment cooling power for cooling the phase change material 26 provide. Accordingly, the shut-off valve 30 opened, and the evaporator plate 16 is flowed through by the expanded refrigerant.

To control the shut-off valve 30 is present a control unit 42 provided (compare 1 ). As long as the controller 42 ensures that the shut-off valve 30 remains in its open position, the phase change material 26 and with this the battery cells 12 cooled. This can be done until by means of the evaporator plate 16 the phase change material 26 and the battery cells 12 are cooled to a lower limit, for example up to a temperature of 20 ° C. Then the controller controls 42 the shut-off valve 30 again, ensuring that the latter is closed.

By such a clocked switching on and off the evaporator plate 16 can the temperature of the battery cells 12 always be kept in a desired temperature range. The corresponding and particularly easy to implement control algorithm for controlling the shut-off valve 30 should be based on 3 be illustrated.

In two in 3 shown graph is on a first ordinate 44 the temperature of the battery cells and on a first abscissa 46 the time t applied. During a first period of time 48 the shut-off valve remains 30 closed, the evaporator plate 16 is thus in a shutdown phase 50 , This is in a second graph in 3 Fig. 1 illustrates in which on an abscissa 52 also the time t and on an ordinate 54 the switching states of the shut-off valve 30 are indicated.

For not treated with the refrigerant evaporator plate 16 First, the temperature of the battery cells increases 12 at. This happens until the phase change material 26 changes its state of aggregation (cf. 2 ). From this time during the first period 48 the temperature of the battery cells remains 12 essentially constant.

Once then a large part of the phase change material 26 has changed its state of aggregation, for example, when at a phase transition from solid to liquid 90% of the phase change material 26 present melted, the shut-off valve 30 open. Accordingly, during a second period of time 54 the evaporator plate 16 in a switched-on state 56 , Switching between the two states takes place at a time 58 instead of.

During the second period 54 once again the temperature of the battery cells remains 12 constant, because first the heat dissipation to a new phase transition of the phase change material 26 , such as changing the state of aggregation from liquid to solid. Only when the phase change material 26 completely in the changed state of aggregation, the pressurization of the evaporator plate 16 with the expanded refrigerant to lower the temperature of the battery cells 12 (see. 3 ).

At a subsequent time 60 have the battery cells 12 reaches a lower limit of the temperature, and the valve 30 is closed again, the evaporator plate 16 So shut off. Accordingly, the temperature changes in a next period of time 62 as for the period 48 described. When subsequently the major part of the phase change material 26 is again present in the again changed state of aggregation, is at a time 64 turn the shut-off valve 30 open. This shown control of the evaporator plate 16 is very easy.

In the 4 shown battery arrangement 10 is essentially the same as in 1 shown, but here are Wärmeleitelemente in the form of Wärmeleitplatten 66 provided, which with the evaporator plate 16 are connected by welding. These heat conducting plates 66 consist of a good heat conductive material. The heat conducting plates 66 can be particularly good at the phase transition of the phase change material 26 released heat on the evaporator plate 16 transfer. The heat conducting plates 66 namely, ensure that between the battery cells 12 and the same is a sufficient temperature difference, in order for a good heat conduction to the evaporator plate 16 to care.

The heat conducting plates 66 are present as well as the phase change material 26 in the interstices 20 between the individual battery cells 12 arranged and in this case completely in the phase change material 26 embedded.

The control unit 42 can also use the expansion valve 14 to flow through the evaporator plate 16 with the refrigerant to enable or prevent. Then on the shut-off valve 30 be waived.

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

• DE 102007050812 A1 [0002]
• DE 102010063057 A1 [0004]
• CN 1870347A [0004]
• DE 102010005097 A1 [0004]
• DE 10358582 A1 [0004]
• DE 102011106690 A1 [0004]
• DE 102007010750 B3 [0005]

Claims (10)

Battery arrangement for a vehicle, having a plurality of battery cells ( 12 ), with a latent heat storage ( 28 ), which is a phase change material ( 26 ) for cooling the battery cells ( 12 ), and with a cooling device for cooling the phase change material ( 26 ), characterized in that the cooling device as evaporator ( 16 ) of an air conditioning system which is connected to one of an expansion device ( 14 ) relaxed refrigerant can be acted upon. Battery arrangement according to claim 1, characterized in that the latent heat storage ( 28 ) with the evaporator ( 16 ) is in plant. Battery arrangement according to claim 1 or 2, characterized in that by the evaporator ( 16 ) a bottom plate of a latent heat storage ( 28 ) and the battery cells ( 12 ) comprehensive assembly of the battery assembly ( 10 ) is formed. Battery arrangement according to one of claims 1 to 3, characterized in that the housing of the individual battery cells ( 12 ) of the phase change material ( 26 ) of the latent heat storage ( 28 ) are enclosed peripherally circumferentially and a bottom surface ( 24 ) of the housing of the respective battery cell ( 12 ) with the phase change material ( 26 ) is in plant. Battery arrangement according to one of Claims 1 to 4, characterized by a control device ( 42 ) for actuating a valve device ( 30 ), which in an open position, a flow through the evaporator ( 16 ) with the refrigerant and in a closed position prevents the flow through. The battery assembly according to claim 5, characterized in that the control device ( 42 ) is designed to prevent the valve device ( 30 ) in the open position and in the closed position in dependence on a temperature of the battery cells ( 12 ) and / or one for a phase transition of the phase change material ( 26 ) time period. Battery arrangement according to one of claims 1 to 6, characterized in that heat-conducting elements ( 66 ) with the evaporator ( 16 ) are connected, by means of which at a phase transition of the phase change material ( 26 ) released heat on the evaporator ( 16 ) is transferable. Battery arrangement according to claim 7, characterized in that the heat-conducting elements ( 66 ) in respective intervals ( 20 ) between the individual battery cells ( 12 ) are arranged. Battery arrangement according to claim 7 or 8, characterized in that the heat-conducting elements ( 66 ) circumferentially of the phase change material ( 26 ) of the latent heat storage ( 28 ) are enclosed. Method for operating a battery arrangement ( 10 ) for a vehicle in which a plurality of battery cells ( 12 ) of the battery arrangement ( 10 ) liberated heat to a phase change material ( 26 ) of a latent heat storage ( 28 ), and in which the phase change material ( 26 ) is cooled by means of a cooling device, characterized in that as the cooling device an evaporator ( 16 ) is used for cooling the phase change material ( 26 ) with a at an expansion device ( 14 ) is applied to relaxed refrigerant.

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