TECHNICAL FIELD

The present disclosure relates to a compressor arrangement configured to compress air to an inlet of a combustion engine. The present disclosure further relates to a combustion engine comprising a compressor arrangement, and a vehicle comprising a combustion engine.

BACKGROUND

Compressor arrangements, such as turbocharger compressor arrangements, are used to compress air to an inlet of a combustion engine. A compressor arrangement can increase the performance of an engine and can increase the fuel efficiency of the engine. Efficiency and performance targets have let to the development of compressor arrangements comprising two compressors arranged in parallel. Compressor arrangements comprising two compressors arranged in parallel offers several advantages, among them the ability to operate one of the two compressors at lower power outputs of the engine, and both compressors at higher power outputs of the engine. Such an operational method provides several advantages and is for example used in sequential parallel turbo arrangements.

However, such compressor arrangements are not very common due their complexity.

By operating only one compressor, at low load situations of an engine, the fuel efficiency can be increased. This because a compressor has a relative low efficiency at low flow rates of air through the compressor. Thus, by turning off one of the compressors at low load situations of an engine, the air flow rate through the second compressor is increased, which increases the efficiency of the compressor and improves the fuel efficiency of the engine. Further, by operating one compressor, the occurrence of turbo lag can be reduced. This because if using one bigger compressor, or if using two compressors simultaneously operating in parallel, such compressors requires more time to accelerate, than a single smaller compressor.

However, turning off one of two compressors is associated with some problems. Firstly, when turning off one compressor, one should preferably in some way restrict airflow through the compressor, in order to not impair the total efficiency of the compressor arrangement by a backflow of air through the compressor. Secondly, the starting of a turned off compressor is associated with some problems. For example, since a compressor requires time to accelerate to start compress air, the compressor is preferably accelerated before an outlet of the compressor is fluidly connected to an inlet of an engine. If not, air tends to flow backwards through the compressor because the working of the active compressor increases the pressure in the inlet of the engine. Such backflow may significantly disturb an

acceleration phase of the compressor and may significantly reduce the efficiency of the compressor arrangement. Further, surge may appear in a compressor working against a restrictor, such as a valve. Surge appears when a pressure ratio over a compressor is high and the air flow over the compressor wheel is low. If so, a flow instability is induced in the compressor and the air tends to go backward over a compressor wheel of the compressor.

A further general problem associated with compressor arrangements is the routing of pipes of the compressor arrangement. Usually, an engine comprising a compressor arrangement is mounted in a confined space with limited dimensions, such as an engine compartment.

Further, when routing the pipes, one should preferably ensure that a person can reach other components in the confined space, for example during a service or repair procedure of components therein.

In addition, in general, today’s market requires high quality arrangements capable of operating in an efficient manner, while the arrangements have conditions and/or

characteristics suitable for being manufactured and assembled in a cost-efficient manner.

SUMMARY

It is an object of the present invention to overcome, or at least alleviate, at least some of the above-mentioned problems and drawbacks.

According to a first aspect of the invention, the object is achieved by a compressor arrangement configured to compress air to an inlet of a combustion engine. The arrangement comprises a first compressor, a second compressor, and a conduit arrangement. The second compressor is arranged in parallel to the first compressor in the conduit arrangement. The arrangement further comprises a valve arranged downstream of the second compressor. The valve comprises an inflow portion and an outflow portion. The arrangement further comprises a bleed flow conduit with an inlet arranged at the inflow portion of the valve.

Since the arrangement comprises a valve arranged downstream of the second compressor, the valve can restrict flow through the second compressor, when the second compressor is not in use. Thereby, a backflow over the second compressor can be avoided when the second compressor is turned off. Since the arrangement comprises a bleed flow conduit with an inlet arranged at the inflow portion of the valve, a bleed flow through the bleed flow conduit facilitates start-up of the second compressor and reduces the risk of surge in the second compressor during start-up thereof. This because the second compressor is allowed to accelerate and to start to compress air before the valve is opened. As a further result thereof, the occurrence of compressor lag is reduced. Thereby, a compressor arrangement is provided capable of improving performance of an engine comprising the compressor arrangement.

Further, since the inlet of the bleed flow conduit is arranged at the inflow portion of the valve, a simple connection of the bleed flow conduit can be provided. Thereby, conditions are provided for a space-efficient routing of pipes, in a confined space, such as an engine compartment of a vehicle. Still further, since the inlet of the bleed flow conduit is arranged at the inflow portion of the valve, conditions are provided for reducing the number of valves required for obtaining an efficient compressor arrangement, as will be further explained herein. In addition, since the inlet of the bleed flow conduit is arranged at the inflow portion of the valve, a compressor arrangement with improved flow characteristics is provided. This because during a start-up phase of the second compressor, air can flow from an outlet of the second compressor to the inflow portion of the valve, and from the inflow portion of the valve through the bleed flow conduit.

Accordingly, a compressor arrangement is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above- mentioned object is achieved.

Optionally, the valve comprises a valve body movable between an open position, in which a fluid connection between the inflow portion and an outflow portion is open, and a closed position, in which the fluid connection is closed. Thereby, a simple and efficient control of flow through the valve can be provided, which provides conditions for an efficient activation and deactivation of the second compressor.

Optionally, the valve body is configured to move from the closed position towards the open position, when a pressure ratio between the inflow portion and the outflow portion is above a predetermined threshold ratio. Thereby, a compressor arrangement is provided capable of opening the valve in an automatic manner, when the second compressor has been accelerated to compress air to an air pressure exceeding the air pressure of the first compressor. As a result, the use of sensors, control arrangements, and actuators for controlling opening of the valve is circumvented, which provides conditions for manufacturing and assembling the compressor arrangement in a cost-efficient manner. Optionally, the valve body is biased towards the closed position. Thereby, a compressor arrangement is provided capable of closing the valve in an automatic manner, for example when the pressure ratio between the inflow portion and the outflow portion is below a predetermined threshold ratio. As a result, the use of sensors, control arrangements, and actuators for controlling closing of the valve is circumvented, which provides conditions for manufacturing and assembling the compressor arrangement in a cost-efficient manner.

Optionally, the inlet of the bleed flow conduit is arranged on the valve body. Thereby, a compressor arrangement is provided having improved flow characteristics.

Optionally, the valve comprises a valve element configured to close the bleed flow conduit when the valve body is in the open position. Thereby, the efficiency of the compressor arrangement is improved. This because a fluid connection through the bleed flow conduit is closed when the second compressor is operating. Thereby, a bleed flow through the bleed flow conduit will not reduce the efficiency of the compressor arrangement during operation of the second compressor. Further, a valve is provided capable of automatically closing the bleed flow conduit when the valve body is in the open position. As a result, the need for sensors, control arrangements, and actuators for controlling flow through the bleed flow conduit is circumvented, which provides conditions for manufacturing and assembling the compressor arrangement in a cost-efficient manner. Still further, since the valve comprises the valve element, the need for a separate valve for controlling flow through the bleed flow conduit is circumvented, which further provides conditions for manufacturing and assembling the compressor arrangement in a cost-efficient manner.

Optionally, the valve comprises a supporting structure arranged to support the valve body, and wherein the bleed flow conduit extends through the supporting structure. Thereby, an efficient routing of the bleed flow conduit is provided in the valve.

Optionally, the valve element is arranged on the supporting structure. Thereby, a simple, efficient, and reliable control of flow through the bleed flow conduit is provided.

Optionally, the valve body is slidably arranged on the supporting structure. Thereby, an efficient supporting of the valve body is provided, while a simple, efficient, and reliable control of flow through the bleed flow conduit is provided.

Optionally, the valve body comprises a bore, wherein the supporting structure extends into the bore, and wherein the valve body comprises a portion of the bleed flow conduit connecting the inlet of the bleed flow conduit and a second opening arranged at the bore. Thereby, an efficient supporting of the valve body is provided, while a simple, efficient, and reliable control of flow through the bleed flow conduit is provided.

Optionally, the valve element comprises an aperture configured to face the second opening, when the valve body is in the closed position. Thereby, a simple, efficient, and reliable control of flow through the bleed flow conduit is provided.

Optionally, a portion of the bore is configured to cover the aperture when the valve body is in the open position. Thereby, a simple, efficient, and reliable control of flow through the bleed flow conduit is provided.

Optionally, an outlet of the first compressor is fluidly connected to the outflow portion of the valve. Thereby, the automatic control of the valve is performed with improved efficiency.

Optionally, the bleed flow conduit comprises an outlet fluidly connected to a portion of the conduit arrangement upstream of at least one of the first and second compressors. Thereby, a compressor arrangement is provided with improved flow characteristics. This because air ducted from the inflow portion of the valve is returned to a portion of the conduit arrangement having a low air pressure during operation of the compressors.

Optionally, the compressor arrangement is a turbocharger compressor arrangement comprising a first turbocharger and a second turbocharger, wherein the first turbocharger comprises a first turbine connected to the first compressor, and wherein the second turbocharger comprises a second turbine connected to the second compressor. Since the arrangement comprises a valve arranged downstream of the second compressor, the valve can restrict flow through the second compressor of the second turbocharger, when the second compressor is not in use. Thereby, a backflow over the second compressor can be avoided when the second compressor is turned off. Since the arrangement comprises a bleed flow conduit with an inlet arranged at the inflow portion of the valve, a bleed flow through the bleed flow conduit facilitates start-up of the second compressor, i.e. acceleration of the second compressor and the second turbine and reduces the risk of surge in the second compressor during start-up. This because the second compressor is allowed to accelerate and to start to compress air before the valve is opened. As a further result thereof, the occurrence of turbo lag is reduced since the second compressor and the second turbine will have time to accelerate before the valve is opened. Thereby, a turbocharger compressor arrangement is provided capable of enhancing performance of an engine comprising the turbocharger compressor arrangement.

Further, since the inlet of the bleed flow conduit is arranged at the inflow portion of the valve, a simple connection of the bleed flow conduit can be provided, which provides conditions for a space-efficient routing of pipes of the turbocharger compressor arrangement in a confined space, for example in an engine compartment of a vehicle. Still further, since the inlet of the bleed flow conduit is arranged at the inflow portion of the valve, conditions are provided for reducing the number of valves required for obtaining an efficient turbocharger compressor arrangement. In addition, since the inlet of the bleed flow conduit is arranged at the inflow portion of the valve, a turbocharger compressor arrangement with improved flow

characteristics is provided. This because during a start-up phase of the second compressor, air can flow from an outlet of the second compressor to the inflow portion of the valve, and from the inflow portion of the valve through the bleed flow conduit.

According to a second aspect of the invention, the object is achieved by a combustion engine comprising a compressor arrangement according to some embodiments, wherein the compressor arrangement is configured to compress air to an inlet of a combustion engine.

Since the combustion engine comprises a compressor arrangement according to some embodiments, a combustion engine is provided with improved performance and a reduced risk of surge in the second compressor, as well as a reduced occurrence of compressor lag. Further, a combustion engine is provided having conditions for a space-efficient routing of pipes of the combustion engine.

Accordingly, a combustion engine is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

According to a third aspect of the invention, the object is achieved by a vehicle comprising a combustion engine according to some embodiments.

Since the vehicle comprises a combustion engine according to some embodiments, a vehicle is provided comprising a combustion engine with improved performance and reduced risk of surge in the second compressor, as well as a reduced occurrence of compressor lag.

Further, a vehicle is provided having conditions for a space-efficient routing of pipes in an engine compartment of the vehicle. Accordingly, a vehicle is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of the invention, including its particular features and advantages, will be readily understood from the example embodiments discussed in the following detailed description and the accompanying drawings, in which:

Fig. 1 illustrates schematically a compressor arrangement, according to some embodiments, Fig. 2 illustrates a cross section of a valve of the compressor arrangement, illustrated in Fig. 1 ,

Fig. 3 illustrates the cross section of the valve illustrated in Fig. 2, with a valve body of the valve in an open position, and

Fig. 4 illustrates a vehicle, according to some embodiments.

DETAILED DESCRIPTION

Aspects of the present invention will now be described more fully. Like numbers refer to like elements throughout. Well-known functions or constructions will not necessarily be described in detail for brevity and/or clarity.

Fig. 1 illustrates schematically a compressor arrangement 1 , according to some

embodiments. The compressor arrangement 1 is configured to compress air to an inlet 3 of a combustion engine 5. The compressor arrangement 1 comprises a first compressor 7, a second compressor 9, and a conduit arrangement 1 1. The conduit arrangement 1 1 is configured to fluidly connect the first and second compressors 7, 9 to the inlet 3 of a combustion engine 5. The second compressor 9 is arranged in parallel to the first

compressor 7 in the conduit arrangement 1 1 . The conduit arrangement 1 1 may further comprise one or more air filter arrangement upstream of the first and second compressors 7, 9. The conduit arrangement 1 1 comprises a junction 12 fluidly connecting a respective outlet 14, 39 of the first and second compressors 7, 9 and the inlet 3 of the engine 5. Further, according to the illustrated embodiments, the conduit arrangement 1 1 comprises a charge air cooler 16, arranged between the junction 12 and the inlet 3 of the engine 5. The charge air cooler 16 is configured to cool compressed air, before the compressed air is ducted to the inlet 3 of the engine 5. Thereby, the performance of the engine 5, and the fuel efficiency of the engine 5, can be improved.

According to the illustrated embodiments, the compressor arrangement 1 is a turbocharger compressor arrangement comprising a first turbocharger 45 and a second turbocharger 47. The first turbocharger 45 comprises a first turbine 49 connected to the first compressor 7, and the second turbocharger 47 comprises a second turbine 51 connected to the second compressor 9. According to further embodiments, the first and/or the second compressor 7, 9 may be another type of compressor, such as an electrically driven compressor, or a mechanically driven compressor.

The compressor arrangement 1 further comprises a valve 13 arranged downstream of the second compressor 9. The valve 13 comprises an inflow portion 15 and an outflow portion 17. The inflow portion 15 is fluidly connected to the outlet 14 of the second compressor 9, and the outflow portion 17 is fluidly connected to the inlet 3 of the engine 5, via the junction 12. The outlet 39 of the first compressor 7 is thus fluidly connected to the outflow portion 17 of the valve 13, via the junction 12. The compressor arrangement 1 further comprises a bleed flow conduit 19 with an inlet arranged at the inflow portion 15 of the valve 13.

According to the illustrated embodiments, the bleed flow conduit 19 comprises an outlet 41 fluidly connected to a portion 43 of the conduit arrangement 1 1 upstream of the first and second compressors 7, 9. According to further embodiments, the outlet 41 of the bleed flow conduit 19 may be connected to another non-pressurized portion of a conduit arrangement, or to the atmosphere.

Fig. 2 illustrates a cross section of the valve 13, illustrated in Fig. 1. The valve 13 comprises a valve body 23 movable between an open position and a closed position. In Fig. 2, the valve body 23 is illustrated in the closed position. When the valve body 23 is in the closed position, a fluid connection is closed between the inflow portion 15 and an outflow portion 17.

According to the illustrated embodiments, the valve body 23 comprises a sealing 26 which further seals the fluid connection between the inflow portion 15 and an outflow portion 17, when the valve body 23 is in the closed position.

Fig. 3 illustrates the cross section of the valve 13 illustrated in Fig. 2, with the valve body 23 in the open position. As can be seen, when the valve body 23 is in the open position, a fluid connection is open between the inflow portion 15 and an outflow portion 17. The valve body 23 is configured to move from the closed position, illustrated in Fig. 2, towards the open position, illustrated in Fig. 3, when a pressure ratio between the inflow portion 15 and the outflow portion 17 is above a predetermined threshold ratio. As indicated in Fig. 2, the valve body 23 is biased towards the closed position by a spring 24.

The following will be explained with reference to Fig. 2. According to the illustrated embodiments, the inlet 21 of the bleed flow conduit 19 is arranged on the valve body 23. The valve body 23 is cone-shaped, and the inlet 21 of the bleed flow conduit 19 is arranged on a cone-shaped surface of the valve body 23 facing the inflow portion 15. The valve 13 comprises a supporting structure 25 arranged to support the valve body 23. The valve body 23 comprises a bore 29. The supporting structure 25 extends into the bore 29. The valve body 23 is slidably arranged on the supporting structure 25 between the open and closed positions. The bleed flow conduit 19 extends through the supporting structure 25.

The valve 13 comprises a valve element 27 configured to close the bleed flow conduit 19 when the valve body 23 is in the open position. According to the illustrated embodiments, the valve element 27 is arranged on the supporting structure 25. The valve body 23 comprises a portion 31 of the bleed flow conduit 19 connecting the inlet 21 of the bleed flow conduit 19 and a second opening 33 arranged at the bore 29. As can be seen in Fig. 2, the valve element 27 comprises an aperture 35 configured to face the second opening 33, when the valve body 23 is in the closed position. Further, as can be seen in Fig. 3, a portion 37 of the bore 29 is configured to cover the aperture 35 when the valve body 23 is in the open position. Thereby, an efficient closing of the bleed flow conduit 19 is provided. The aperture 35, illustrated in Fig. 2 and Fig. 3, is connected to the outlet 41 of the bleed flow conduit 19, illustrated in Fig. 1. Thus, when the valve body 23 is in the closed position, as illustrated in Fig. 2, air can flow from the inflow portion 15 of the valve 13, into the inlet 21 of the bleed flow conduit 19 and through the portion 31 of the bleed flow conduit 19, through the aperture 35, towards the outlet 41 of the bleed flow conduit 19, illustrated in Fig. 1. When the valve body 23 is in the open position, as illustrated in Fig. 3, air is blocked from flowing through the bleed flow conduit 19 because the portion 37 of the bore 29 is covering the aperture 35.

The turbocharger compressor arrangement 1 , illustrated in Fig. 1 , comprises an exhaust valve 32. In Fig. 1 , the exhaust valve 32 is illustrated as being arranged downstream of the second turbine 51. Flowever, as an alternative, the exhaust valve 32 may be arranged upstream of the second turbine 51 . By closing the exhaust valve 32, all exhaust gas from an outlet manifold 34 is ducted through the first turbine 49 of the first turbocharger 45. The first turbine 49 will spin a turbine wheel of the first compressor 7, and the first compressor 7 will compress air to the inlet 3 of the engine 5. Since the exhaust valve 32 is closed, no exhaust gas will be ducted through the second turbine 51 of the second turbocharger 47. As a result thereof, the second turbine 51 and a compressor wheel of the second compressor 9 will be at stand still. When the first compressor 7 is operating and the second compressor is at stand still, the pressure at the outflow portion 17 of the valve 13 is higher than the pressure at the inflow portion 15 of the valve 13.

The following will be explained with simultaneous reference to Fig. 1 - Fig. 3. As a result of the pressure difference between the outflow portion 17 and the inflow portion 15, the valve body 23 is further pressed towards the closed position. When the first compressor 7 is operating and the second compressor is at stand still, the pressure at the outflow portion 17 of the valve 13 approximately corresponds to the boost pressure of the first compressor 7, and the pressure at the inflow portion 15 of the valve 13 approximately corresponds to an atmospheric pressure, because the second compressor 9 is at stand still.

If for example a power demand of the engine 5 increases, a control unit of the engine 5 may start to control the exhaust valve 32 to a partially open position, or to a fully open position. As a result, exhaust gas will start to flow also through the second turbine 51 of the second turbo compressor 47. Thereby, the second turbine 51 and a compressor wheel of the second compressor 9 start to rotate and begin an acceleration phase. During the acceleration phase of the second compressor 9, air can flow from the outlet 14 of the second compressor 9 into the inflow portion 15 of the valve 13, and out from the inflow portion 15 of the valve 13 via the bleed flow conduit 19. In this manner, the second compressor 9 can accelerate in an efficient manner despite the fact that the valve 13 is in the closed position.

When the compressor wheel of the second compressor 9 reaches a rotational velocity sufficient for causing the pressure ratio between the inflow portion 15 and the outflow portion 17 of the valve 13 to rise above the predetermined threshold ratio, the valve body 23 is displaced from the closed position to the open position. As a result, the outlet 14 of the second compressor 9 is fluidly connected to the inlet 3 of the engine 5, and the second compressor 9 will compress air to the inlet 3 of the engine 5. Further, when the valve body 23 is displaced from the closed position to the open position the valve element 27 closes the bleed flow conduit 19. In this manner, substantially all air compressed by the second compressor 9 is ducted to the inlet 3 of the engine 5.

If for example the power demand of the engine 5 decreases, a control unit of the engine 5 may control the exhaust valve 32 to a closed position. As a result, exhaust gas will stop to flow through the second turbine 51 of the second turbo compressor 47. Thereby, the second turbine 51 and a compressor wheel of the second compressor 9 starts to slow down. When the compressor wheel of the second compressor 9 reaches a rotational velocity sufficiently low for causing the pressure ratio between the inflow portion 15 and the outflow portion 17 of the valve 13 to decline below the predetermined threshold ratio, the valve body 23 is displaced from the open position to the closed position. In this manner, the first compressor 7 will alone compress air to the inlet 3 of the engine. When the engine 5 is turned off, the biasing of the spring 24 ensures that the valve body 23 is in the closed position.

Thus, according to the illustrated embodiments, the valve 13 can assume the open and the closed position without the need for actuators, sensors, control units, and the like. In addition, the valve 13 can open and close the bleed flow conduit 19 in an efficient manner without the need for actuators, sensors, control units, and the like.

In the above, some features and advantages are described with reference to a turbocharger compressor arrangement. However, according to further embodiments, the first compressor 7, and/or the second compressor 9, may form part of another type of compressor devices, such as an electrically driven compressor device, or a mechanically driven compressor device. Thus, the activation and deactivation of the second compressor 9 may be performed in another manner than by using an exhaust valve 32, for example electrically or

mechanically.

According to the illustrated embodiments, the bleed flow conduit 19 comprises two inlets 21 arranged on the valve body 23. According to further embodiments, the bleed flow conduit 19 may comprise another number of inlets, such as one, three, four, or the like. According to still further embodiments, the bleed flow conduit 19 may comprise one or more inlets arranged at another component of the inflow portion 15 of the valve 13, such as a wall of the inflow portion 15. Further, as indicated in Fig.1 , the second compressor 9 may be larger in size and capacity than the first compressor 7. Thereby, the efficiency range of the compressor arrangement 1 is further widened.

The combustion engine 1 , as referred to herein, may be a compression ignition engine, such as a diesel engine, or an Otto engine with a spark-ignition device, wherein the Otto engine may be configured to run on gas, petrol, alcohol or similar volatile fuels or combinations thereof.

Fig. 4 illustrates a vehicle 53, according to some embodiments. The vehicle 53 comprises wheels 54 and a combustion engine 5 according to the embodiments illustrated in Fig. 1. The combustion engine 5 is configured to provide motive power to the vehicle 53 via one or more of the wheels 54 of the vehicle 53. The vehicle 53 illustrated in Fig. 4 is a truck. However, the combustion engine 5, as referred to herein, may be comprised in another type of manned or unmanned vehicle for land or water-based propulsion such as a lorry, a bus, a construction vehicle, a tractor, a car, a boat, a ship, or the like. Further, the combustion engine 5, as referred to herein, may be a stationary internal combustion engine, for example an internal combustion engine of an engine driven generator.

It is to be understood that the foregoing is illustrative of various example embodiments and that the invention is defined only by the appended claims. A person skilled in the art will realize that the example embodiments may be modified, and that different features of the example embodiments may be combined to create embodiments other than those described herein, without departing from the scope of the present invention, as defined by the appended claims. As used herein, the term "comprising" or "comprises" is open-ended, and includes one or more stated features, elements, steps, components or functions but does not preclude the presence or addition of one or more other features, elements, steps, components, functions or groups thereof.