WO2011102784A1

WO2011102784A1 - Arrangement for preventing ice formation in a charge air cooler

Info

Publication number: WO2011102784A1
Application number: PCT/SE2011/050136
Authority: WO
Inventors: Zoltan Kardos; Erik SÖDERBERG
Original assignee: Scania Cv Ab
Priority date: 2010-02-19
Filing date: 2011-02-07
Publication date: 2011-08-25
Also published as: SE1050162A1; EP2536931A1; EP2536931A4; SE534618C2; BR112012018477A2

Abstract

The present invention relates to an arrangement for preventing ice formation in a charge air cooler which comprises a radiator portion (3) in which compressed air is cooled by surrounding air which flows through the radiator portion (3). The arrangement comprises a first flow element (7a) which in a closed position is adapted to preventing compressed air from being led through a region (A) of the radiator portion (3), a second flow element (7b) which in a closed position is adapted to preventing compressed air from being led through a second region (B) of the radiator portion (3) which is larger than the first region of the radiator portion (A), and a control unit (10) adapted to receiving information concerning at least one parameter (11, 12, 14) which is related to the risk of ice formation in the charge air cooler, which control unit (10), in cases where said parameter or parameters indicate that there is risk of ice formation in the charge air cooler, is adapted to placing one of the flow elements (7a, 7b) in a closed position so that the compressed air is led through a reduced region (R_A, R_B) of the radiator portion (3).

Description

ARRANGEMENT FOR PREVENTING ICE FORMATION IN A CHARGE AIR COOLER

BACKGROUND TO THE INVENTION AND PRIOR ART

The present invention relates to an arrangement for preventing ice formation in a charge air cooler according to the preamble of claim 1. The amount of air which can be supplied to a supercharged combustion engine in a vehicle depends on the pressure of the air but also on the temperature of the air.

Supplying as large an amount of air as possible to a supercharged combustion engine entails the compressed air being cooled in a charge air cooler before it is led to the combustion engine. The charge air cooler is generally situated in front of the conventional radiator in a vehicle. A charge air cooler usually comprises two tanks and a plurality of mutually parallel tubular elements which connect the tanks to one another. The parallel tubular elements are disposed at a distance from one another so that surrounding cold air can flow between them and cool the compressed air within them. Depending on the size of the charge air cooler, the compressed air can be cooled to a temperature more or less corresponding to the temperature of the surrounding air.

Charge air coolers in vehicles are usually so dimensioned that they are of relatively good efficiency. In circumstances where a cold ambient temperature prevails and/or the air is at very high humidity, the compressed air may be cooled in charge air coolers to a temperature which is lower than the dew point temperature of the air. The water vapour in the compressed air condenses, with the result that water in liquid form precipitates within the charge air cooler. When the temperature of the surrounding air is very low, there is also risk that the water condensed may freeze to ice within the charge air cooler. In such circumstances, the air flow ducts in the charge air cooler are obstructed by ice and the air supply to the engine becomes deficient or ceases completely, causing the combustion engine to stop. SUMMARY OF THE INVENTION

The object of the present invention is to propose an arrangement which effectively prevents ice from forming in an air-cooled charge air cooler even in situations where the air which cools the charge air is at a very low temperature.

This object is achieved with an arrangement of the kind mentioned in the introduction which is characterised by the features indicated in the characterising part of claim 1. When there is risk of ice formation in the charge air cooler, one of the flow elements is placed in a closed position so that the compressed air is led through a reduced region of the radiator portion. The fact that the compressed air is led through a reduced region of the radiator portion results in a higher flow velocity than if it is led through the whole radiator portion. The compressed air will therefore not be cooled in the charger cooler to the same low temperature as when the whole radiator portion is used. In situations where there is risk of ice formation, the control unit chooses to place in the closed position the flow element which effects the most appropriate reduction of the charge air cooler's capacity. The compressed air is thus cooled to a low temperature in the charge air cooler but not to such a low temperature that there is risk of ice formation in the charge air cooler.

According to an embodiment of the present invention, the larger region of the radiator portion comprises the whole of the smaller region of the radiator portion. In this case the second flow element may be situated upstream of the first flow element. When the second flow element is moved to the closed position, it blocks the supply of compressed air to the first flow element situated downstream. This is a simple way of achieving two reduced regions of the radiator portion which are of different sizes. The arrangement comprises with advantage at least a third flow element which in a closed position is intended to prevent compressed air from being led through a third region of the radiator portion which is larger than the second region of the radiator portion. The cooling of the compressed air can thus be subjected to a further step of reduction. The third flow element is situated with advantage upstream of the first two flow elements. The third region of the radiator portion will thus comprise both the first region and the second region of the radiator portion.

According to a preferred embodiment of the present invention, the arrangement comprises a sensor adapted to detecting a parameter in the form of the temperature of the surrounding air. A prerequisite for it to be possible for ice formation to take place is that the surrounding air which cools the compressed air in the radiator portion is at a temperature below 0°C. It is therefore appropriate to detect this parameter in order to assess whether there is risk of ice formation. However, there is not always risk of ice formation in the charge air cooler when the surrounding air is at a temperature below 0°C. The control unit may therefore also be adapted to handling information about a parameter related to the load upon a combustion engine. When a supercharged combustion engine is under severe load, a relatively large amount of compressed air at a high temperature is supplied to the charge air cooler. In this case there is no risk of ice formation in the charge air cooler unless the surrounding air is at an extremely low temperature. In situations where the load upon the supercharged combustion engine is low, a relatively small amount of compressed air at a relatively low temperature is led to the charge air cooler. In this case there is very great risk of ice formation in the charge air cooler even when surrounding air temperatures are only just below 0°C. The control unit can use the aforesaid parameters to assess whether there is risk of ice formation and, if such is the case, it can place one of said flow elements in the closed position so that the compressed air is cooled in a region of the radiator portion which is of appropriate size. Alternatively, or in combination, the arrangement may comprise a sensor adapted to detecting a parameter in the form of the temperature of the compressed air which is led out from the charge air cooler. If the compressed air leaving the charge air cooler is at a temperature below 0°C, ice formation takes place within the charge air cooler. The control unit can use this information to decide whether there is risk of ice formation and, if such is the case, it can close one of said flow elements so that the region for cooling the compressed air is reduced appropriately. If thereafter it receives information indicating that the compressed air leaving the charge air cooler is at a temperature definitely over 0°C, the control unit can return the flow element to an open position.

According to a preferred embodiment of the present invention, the charge air cooler comprises a tank intended to receive the compressed air before or after it has been cooled in the radiator portion, and said flow elements are situated within said tank. Most conventional charge air coolers are provided with a warm inlet tank on one side of the radiator portion to accumulate the warm compressed air before it is cooled, and a cold outlet tank on the opposite side of the radiator portion to accumulate the cooled compressed air. The flow elements may be at a protected location within one of these tanks. The flow elements may be arranged after one another within, for example, such an inlet tank so that the flow element situated furthest upstream defines the region of the radiator portion which is used for cooling the compressed air.

According to a preferred embodiment of the present invention, the control unit is adapted to using separate power means for placing the individual flow elements in desired positions. Such separate power means may be electric motors or other similar components such as pneumatic or hydraulic cylinders. Alternatively, the control unit may be adapted to using a common power means and a motion-transmitting mechanism to place the individual flow elements in desired positions. In this case different degrees of activation of the power means may be converted to movements of the flow elements so that they are switched successively to the closed position. The motion-transmitting mechanism may comprise a regulating bar adapted to linear movement and the individual flow elements may comprise contact means intended to be in contact with a control surface of the regulating bar. The contact surface may comprise recesses which, when the contact means reaches such a recess, impart a motion which moves the respective flow elements from the open position to the closed position.

Although the object of the invention is to eliminate ice formation in the charge air cooler, said flow elements may also be used in other situations where it is

advantageous to reduce the cooling of the compressed air in the charge air cooler. Such a situation is where the exhaust gases are at such a low temperature that they do not undergo desired cleaning in an exhaust-cleaning component which may be a catalyst. When a vehicle is set in motion from cold or the load upon the combustion engine is low, the exhaust gases from the combustion engine may be at too low a temperature for the catalyst. In such cases the control unit can place one of said flow elements in the closed position so that the compressed air is led through a reduced region of the charge air cooler. The air led to the combustion engine may thus be at a higher temperature, as also exhaust gases, which thereby warm catalysts to a desired temperature. BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are described below by way of example with reference to the attached drawings, in which:

Fig. 1 depicts a charge air cooler according to a first embodiment of the present invention and

Fig. 2 depicts a charge air cooler according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Fig. 1 depicts a charge air cooler which may be fitted at a front portion of a vehicle which is powered by a schematically depicted supercharged combustion engine 1. A supercharged combustion engine 1 needs to be supplied with compressed air. The purpose of the charge air cooler is to cool the compressed air before it is led to the engine 1. The cooling results in the air becoming more compact and hence in it being possible for a larger amount of air to be supplied to the engine. The charge air cooler comprises an inlet tank 2 which, via an inlet aperture 2a, receives warm compressed air from an undepicted compressor. The charge air cooler comprises a radiator package 3 extending between the first tank 2 and an outlet tank 4 which receives the compressed air after cooling in the radiator package 3. The radiator package 3 comprises a plurality of tubular elements 5 extending in a substantially rectilinear manner in a common plane between the inlet tank 2 and the outlet tank 4. The tubular elements 5 are disposed parallel at substantially uniform spacing from one another so that regular gaps 6 are formed between adjacent tubular elements 5.

Surrounding air can therefore flow through the gaps 6 between the tubular elements 5. The gaps 6 are provided with folded heat transfer elements to increase the heat transfer surface between the surrounding air and the tubular elements 5. The tubular elements 5 may be provided with internal elements such as turbulators to enhance the cooling of the compressed air within the tubular elements 5. The flow of surrounding air through the radiator package 3 is provided by the vehicle's movement and/or by a radiator fan which draws air through the radiator package 3. The surrounding air cools the compressed air led through the tubular elements 5. The cooled compressed air is led out from the outlet tank 4 via an outlet aperture 4a. The compressed air may where applicable be mixed with recirculating exhaust gases before it is led to the

supercharged combustion engine 1.

In this case a first flow element 7a, a second flow element 7b and a third flow element 7c are disposed within the inlet tank 2. The flow elements 7a, 7b, 7c are disposed at different levels in the inlet tank 2. The flow elements 7a, 7b, 7c are adapted to being pivotable about an articulation between an open position and a closed position. A seat 8a, 8b, 8c defines the closed position for each of the respective flow elements 7a, 7b, 7c. The seat 8a, 8b, 8c may extend wholly or partly round an internal surface of the inlet tank 2. In Fig. 1 the first flow element 7a and the third flow element 7c are in an open position, whereas the second flow element 7b is in a closed position. The shape of the flow elements 7a, 7b, 7c is such that in the closed position they completely block the internal cross-section of the inlet tank 2. When a flow element 7a, 7b, 7c is in the closed position, the compressed air is subject to a positive pressure in the inlet tank 2 upstream of the flow elements 7a, 7b, 7c. This positive pressure pushes the flow element 7a, 7b, 7c towards the seat 8a, 8b, 8c, resulting in a tight connection between the flow element 7a, 7b, 7c and the seat 8a, 8b, 8c. In this case the flow elements 7a, 7b, 7c are each arranged to be movable between the open and the closed position by their respective electric motors 9a, 9b, 9c. Alternatively, the flow elements 7a, 7b, 7c may be arranged to be movable by some other power means, e.g. pneumatic or hydraulic cylinders.

When the first flow element 7a is in a closed position, the compressed air is prevented from being led to a portion of the inlet tank 2 which is situated downstream of the first flow element 7a. This lower portion of the inlet tank 2 is in communication with a lower region A of the radiator package 3 which comprises a small number of tubular elements 5. When the first flow element 7a is in the closed position, the compressed air which is upstream of the first flow element 7a in the inlet tank 2 is led to a region R_A of the radiator package 3. When the second flow element 7b is in a closed position, the compressed air is prevented from being led to a portion of the inlet tank 2 which is situated downstream of the second flow element 7b. This portion of the inlet tank 2 is in communication with a region B of the radiator package 3 which comprises a larger number of tubular elements 5. The compressed air which is upstream of the second flow element 7b is led to a region R_B of the radiator package 3 which comprises remaining tubular elements 5. When the third flow element 7c is in a closed position, the compressed air is prevented from being led to a portion of the inlet tank 2 which is situated downstream of the third flow element 7c. This portion of the inlet tank 2 is in communication with a region C of the radiator package 3 which comprises a large proportion of the tubular elements 5. The compressed air is led in this case from the portion of the inlet tank which is situated upstream of the third flow element 7c to a region Rc of the radiator package 3 where there is only a small number of tubular elements 5.

A control unit 10 is adapted to receiving information concerning at least one parameter related to the risk of ice formation in the charge air cooler. A relevant such parameter is the temperature of the surrounding air which cools the compressed air in the charge air cooler. The control unit 10 is adapted accordingly to receiving information from a temperature sensor 11 concerning the temperature of the surrounding air. If surrounding air is at a higher temperature than 0°C, there is no risk of ice formation in the charge air cooler, but if surrounding air is at a lower temperature than 0°C, there is risk of ice formation. The risk of ice formation also depends on other parameters such as the velocity of the cooling air flow through the charge air cooler and the temperature and flow of the compressed air. The compressed air's temperature and flow are related to the load upon the combustion engine 1. The control unit 10 is here adapted to handling information 12 concerning the load upon the combustion engine 1. The control unit 10 is also adapted to receiving information from a sensor 13 which is related to the temperature of the exhaust gases when they leave the combustion engine 1. Acceptable cleaning of the exhaust gases by an exhaust-cleaning component, e.g. a catalyst, depends on the exhaust gases not being at too low a temperature. During operation of the vehicle, the control unit 10 receives information from, inter alia, the sensor 11 about the temperature of the surrounding air. If the temperature of the surrounding air is over 0°C, the control unit 10 finds that there is no risk of ice formation in the charge air cooler. The control unit also receives information from the sensor 13 which detects the temperature of the exhaust gases. When the vehicle is being set in motion or is in a low-load state the exhaust gases may be at an

unacceptably low temperature. In such a case, the control unit 10 can place one of the flow elements 7a, 7b, 7c in the closed position so that the compressed air is led through one of the regions RA, RB, RC of the radiator package 3. When the vehicle is moving off from cold, the third flow element 7c may be placed in the closed position, resulting in warm exhaust gases which quickly warm the catalyst. If it receives, during operation of the vehicle, information from the sensor 11 which indicates that the temperature of the surrounding air is below 0°C, the control unit 10 finds that there may be risk of ice formation in the charge air cooler. The lower the temperature of the surrounding air, the greater the risk of the compressed air being cooled to a temperature below 0°C, resulting in formation of ice in the charge air cooler. The control unit 10 substantially continuously receives information 12 concerning the load upon the combustion engine 1. In operating situations where there is a high load upon the combustion engine 1, a large flow of compressed air at a high temperature is led to the charge air cooler. In such circumstances the whole of the charge air cooler's radiator package 3 is usually employed to cool the compressed air without risk of ice formation in the charge air cooler. In operating situations where the load is low, a relatively small air flow at a relatively low temperature is led to the charge air cooler. In this case there is great risk of ice formation in the charge air cooler. The control unit 10 uses parameter values received to determine to what extent the cooling has to be limited in the radiator package 3 in different situations, followed by the control unit 10 closing one of the flow elements 7a, 7b, 7c by means of the respective electric motor 9a, 9b, 9c. In this case the cooling in the radiator package 3 may be reduced in three different steps. This may entail, as depicted in Fig. 1, the second flow element 7b being closed so that the compressed air is led through the region R_B of the radiator package 3. The compressed air is thus led at a higher velocity through the tubular elements 5 in the region R_B than it would be led through all of the tubular elements 5 in the radiator package 3. The compressed air will thus not be cooled to the same low temperature as when the whole of the radiator package 3 is used for cooling it. The compressed air thus undergoes cooling in the charge air cooler to a temperature which is low but higher than 0°C. The risk of ice formation in the charge air cooler is therefore eliminated.

Fig. 2 depicts an alternative embodiment of the invention. In this case one electric motor 15 is used to position all three flow elements 7a, 7b, 7c in an open position and a closed position. The electric motor 15 is here adapted to moving a regulating bar 17 by means of a gearwheel 16 connected to a toothed rack 17d on the regulating bar 17.

The regulating bar 17 is provided with a control surface 17e adapted to cooperating with a respective control means 7ai, 7b i, 7c i of each of the flow elements 7a, 7b, 7c.

The control means 7ai, 7bi, 7ci are each disposed on a protruding portion which forms an angle of 90° with the respective flow element 7a, 7b, 7c. The control surface 17e comprises three recesses 17a, 17b, 17c. The respective flow elements 7a, 7b, 7c comprise spring means adapted to exerting a spring force on the control means 7&_\, 7bi, 7c i so that they are pressed against the control surface 17e. When the regulating bar 17 is in a lower position, each of the control means 7ai, 7bi, 7c i will be in its respective recess 17a, 17b, 17c. Fig. 2 depicts the regulating bar 17 when it has been moved slightly upwards so that the first control means 7ai has moved out of the recess 17a. When the first control means 7ai leaves the recess 17a, it pivots through 90°. The control means 7ai thus also pivots the first flow element through 90°, switching it from the open position to the closed position. When the regulating bar 17 is moved slightly further upwards, the second control means 7b i likewise moves out of the recess 17b. The second control means 7b i thus pivots the second flow element from the open position to the closed position. When the regulating bar 17 is moved yet slightly further upwards, the third control means 7ci likewise moves out of the recess 17c. The third control means 7c i thus pivots the third flow element 7c from the open position to the closed position. Moving the regulating bar step by step upwards from an initial lower position makes it possible for the flow elements 7a, 7b, 7c to be moved successively towards their closed positions by the electric motor 15.

In this case the control unit 10 receives information from a sensor 14 which detects the temperature of the compressed air leaving the charge air cooler. When the compressed air leaving the charge air cooler is at a temperature over 0° there is no risk of ice formation within the charge air cooler. If the compressed air leaving the charge air cooler is at a temperature below 0°C, there is imminent risk of ice formation within the charge air cooler. In such circumstances the control unit 10 can activate the electric motor 15 to move the regulating bar 17 upwards so that the flow element 7a, 7b, 7c situated furthest upstream in the inlet tank 2 defines the region RA, RB, RC of the radiator package 3 which is utilised for cooling the compressed air. During operation, the control unit 10 substantially continuously receives information from the sensor 14 concerning the temperature of the compressed air leaving the charge air cooler. The control unit can therefore at relatively short intervals move the regulating bar 17 between appropriate positions so that the air leaving the charge air cooler will substantially continuously be at a temperature which is low but always higher than 0°C. The control unit 10 here again receives information 12 concerning the load upon the combustion engine. This information may make it possible for the control unit 10 to guide the regulating bar 17 to appropriate positions with greater precision. In this case the control unit 10 likewise receives information from a sensor 13 which detects the temperature of the exhaust gases. The control unit 10 can thus here again reduce the capacity of the charge air coolers when, for example, the vehicle is being set in motion, in order to achieve a necessary exhaust temperature at which desired cleaning of the exhaust gases is achieved. The invention is in no way limited to the embodiment described with reference to the drawings but may be varied freely within the scopes of the claims. In the

embodiments described above, the capacity of the charge air cooler is limited in three steps. It is of course possible to limit the capacity of the charge air cooler in two steps or in more than three steps.

Claims

1. An arrangement for preventing ice formation in a charge air cooler which comprises a radiator portion (3) in which compressed air is cooled by surrounding air which flows through the radiator portion (3), characterised in that the arrangement comprises a first flow element (7a) which in a closed position is adapted to preventing compressed air from being led through a region (A) of the radiator portion (3), a second flow element (7b) which in a closed position is adapted to preventing compressed air from being led through a second region (B) of the radiator portion (3) which is larger than the first region of the radiator portion (A), and a control unit (10) adapted to receiving information concerning at least one parameter (11, 12, 14) which is related to the risk of ice formation in the charge air cooler, which control unit (10), in cases where said parameter or parameters indicate that there is risk of ice formation in the charge air cooler, is adapted to placing one of the flow elements (7a, 7b) in a closed position so that the compressed air is led through a reduced region (RA, RB) of the radiator portion (3).

2. An arrangement according to claim 1, characterised in that the larger region (B) of the radiator portion (3) comprises the whole of the smaller region (A) of the radiator portion (3).

3. An arrangement according to claim 1 or 2, characterised in that the arrangement comprises at least a third flow element (7c) which in a closed position is adapted to preventing compressed air from being led through a third region (C) of the radiator portion which is larger than the second region of the radiator portion (B).

4. An arrangement according to any one of the foregoing claims, characterised in that the arrangement comprises a sensor (11) adapted to detecting a parameter in the form of the temperature of the surrounding air.

5. An arrangement according to any one of claims 1 to 4 above, characterised in that the arrangement comprises a sensor (14) adapted to detecting a parameter in the form of the temperature of the compressed air which is led out from the charge air cooler.

6. An arrangement according to any one of the foregoing claims, characterised in that the control unit (10) is adapted to handling information concerning a parameter which is related to the load upon a combustion engine (1).

7. An arrangement according to any one of the foregoing claims, characterised in that the charge air cooler comprises a tank (2, 4) intended to receive the compressed air before or after it has been cooled in the radiator portion (3), said flow elements (7a, 7b, 7c) being situated within said tank (2, 4).

8. An arrangement according to any one of the foregoing claims, characterised in that the control unit (10) is adapted to using separate power means (9a, 9b, 9c) to place the individual flow elements (7a, 7b, 7c) in desired positions.

9. An arrangement according to any one of claims 1 to 7 above, characterised in that the control unit (10) is adapted to using a common power means (15) and a motion- transmitting mechanism (16, 17, 7ai, 7bi, 7ci) to place the individual flow elements (7a, 7b, 7c) in desired positions.

10. An arrangement according to claim 9, characterised in that the motion- transmitting mechanism (16, 17, 7ai, 7bi, 7ci) comprises a regulating bar (17) adapted to being movable and that the individual flow elements (7a, 7b, 7c) comprise contact means (7ai, 7bi, 7ci) adapted to being in contact with a control surface (17e) of the regulating bar (17).