Supercharger motor system for a motor vehicle

Abstract

Supercharger motor system for a motor vehicle, comprising: an internal combustion engine, a small-capacity, variable-geometry turbocharger designed to meet the charge air requirement up to a predefined supply value, and an electrically driven compressor arranged in parallel to the turbocharger, which is operated by an electronic control unit, wherein the engine is configured to receive a primary supply of charge air during normal engine operation below the predefined supply value from the turbocharger and to receive an additional supply of charge air from the electrically driven compressor when it is necessary to meet a temporary high demand for charge air above the predefined supply value, and a recirculation circuit to build up pressure when the electrically driven compressor starts up before the electrically driven compressor is connected to the engine, wherein the recirculation circuit includes an electrically controlled recirculation valve for directing the airflow through a duct connecting an outlet of the electrically driven compressor to an inlet of the electrically driven compressor.an electrically controlled shut-off valve positioned between the outlet of the electrically operated compressor and the motor for selectively isolating the outlet of the electrically operated compressor from the motor, and a non-return valve to prevent backflow of air from the inlet of the electrically operated compressor into the atmosphere, wherein the electronic control unit is configured to , Keeping the electrically controlled return valve open and the electrically controlled shut-off valve closed when the electrically operated compressor starts up, until the pressure in the return circuit reaches a predefined limit value, and in response to reaching the predefined limit value, opening the electrically controlled shut-off valve and closing the electrically controlled return valve.

Description

[0001] This invention relates to motor vehicles and in particular to a supercharger motor system of a motor vehicle with an internal combustion engine and compressor means for increasing the pressure of the air entering the engine.

[0002] It is known to equip an internal combustion engine of a motor vehicle with a turbocharger to increase the pressure of the air entering the engine in order to improve the combustion efficiency and the torque output.

[0003] A problem with such turbocharged engines is that, even if a variable geometry turbocharger is used, the overall performance of the engine is affected by the fact that the turbocharger must normally be designed to accommodate the maximum flow of exhaust gas from the engine to a turbine of the turbocharger when the engine is operating at maximum engine speed with a wide-open throttle valve.

[0004] This necessitates the use of a large-capacity turbocharger to prevent excessively high backpressure on the engine and / or turbocharger overspeeding at very high exhaust flow rates. However, the use of a large-capacity turbocharger has the disadvantage that at low engine speeds, the exhaust flow rate from the engine is too low to provide a sudden increase in boost pressure if there is a sudden increase in demand from the driver, often resulting in so-called 'turbo lag'.

[0005] To overcome this problem, it has been proposed to use an electrically driven compressor to continuously assist the turbocharger at low to medium engine speeds, with the turbocharger taking over at higher engine speeds.

[0006] Although such an approach overcomes the aforementioned problem of 'turbo lag', it introduces another problem, namely that such continued use of the electrically driven compressor places a heavy load on the vehicle's electrical charging circuit, thereby increasing fuel consumption and, in some cases, requiring additional electrical storage capacities to ensure the operation of the electrically driven compressor at very low engine speeds when the output of the vehicle's electrical charging circuit is unable to meet all imposed electrical requirements.

[0007] It was further proposed in JP 2010 - 048 225 A to use a first and a second turbocharger and an electric motor to start up the second turbocharger in order to reduce fluctuations in turbocharger pressure when switching to the second turbocharger, which would otherwise occur. However, such an arrangement is very complex in design and requires numerous valves and also the use of an electric motor capable of withstanding the very high temperatures in the turbine section of the second turbocharger.

[0008] Furthermore, DE 20 2013 103 691 U1 discloses a turbocharger motor system for a motor vehicle, comprising: an internal combustion engine, a small-capacity variable-geometry turbocharger dimensioned to meet the charge air requirement up to a predefined supply value, and an electrically operated compressor arranged in parallel to the turbocharger and operated by an electronic control unit, wherein the engine is configured to receive a primary charge air supply from the turbocharger during normal engine operation below the predefined supply value and to receive an additional charge air supply from the electrically operated compressor when it is necessary to meet a temporary high charge air requirement above the predefined supply value.

[0009] EP 2 767 701 A1 discloses various charging devices and their use primarily during engine start-up. An electric compressor with some of the valves mentioned in claim 1 is shown. One of the arrangements of electrically operated compressor and turbocharger can also be engaged during steady-state operation, wherein the air supplied by the electrically operated compressor can originate from either a bypass path or, via an inlet path, from a primary charging path, according to a choice of a parallel or series arrangement.

[0010] One objective of this invention is to provide a supercharger motor system that overcomes the problems of the aforementioned prior art.

[0011] According to a first aspect of the present invention, a turbocharger motor system for a motor vehicle is provided, comprising an internal combustion engine, a small-capacity variable-geometry turbocharger dimensioned to meet the charge air requirement up to a predefined supply value, and an electrically driven compressor arranged in parallel to the turbocharger, wherein the engine is configured to receive a primary supply of charge air from the turbocharger during normal engine operation below the predefined supply value and to receive an additional supply of charge air from the electrically driven compressor when it is necessary to meet a temporary high charge air requirement above the predefined supply value, and a recirculation circuit to build up pressure when the electrically driven compressor starts up before the electrically driven compressor is connected to the engine.wherein the recirculation circuit comprises an electrically controlled recirculation valve for directing the airflow through a line connecting an outlet of the electrically driven compressor to an inlet of the electrically driven compressor, an electrically controlled shut-off valve positioned between the outlet of the electrically driven compressor and the motor for selectively isolating the outlet of the electrically driven compressor from the motor, and a check valve to prevent the backflow of air from the inlet of the electrically driven compressor to the atmosphere, wherein, during the start-up of the electrically driven compressor, the electrically controlled recirculation valve is held open and the electrically controlled shut-off valve is held closed until the pressure in the recirculation circuit reaches a predefined limit value.whereupon the electrically controlled shut-off valve opens and the electrically controlled return valve closes.

[0012] The non-return valve can be a check valve designed to prevent the flow of air from the inlet of the electrically operated compressor back into the atmosphere.

[0013] Alternatively, the non-return valve can be an electrically controlled non-return valve designed to close automatically if the pressure at the inlet to the electrically operated compressor is greater than atmospheric pressure, in order to prevent the flow of air from the inlet of the electrically operated compressor back into the atmosphere.

[0014] There can be a first flow path from the atmosphere through the turbocharger to the engine and a second flow path, arranged parallel to the first flow path, from the atmosphere through the electrically operated compressor between a position upstream of the engine and a source of atmospheric air.

[0015] The position upstream of the engine can be an inlet to an intercooler with an outlet designed to direct air to the engine, and the system further includes an air filter through which all air for the engine flows from the atmospheric air source, and the first and second airflow paths each have a low-pressure end connected to an outlet of the air filter.

[0016] The first airflow path can have a first section connected at one end to the air filter and at the other end to an inlet of a turbocharger compressor, and a second section connected at one end to an outlet of the turbocharger compressor and at the other end to the inlet of the charge air cooler; the second airflow path can have a first section with the check valve connected at one end to the air filter and at the other end to the inlet of the electrically driven compressor, and a second section connected at one end to the outlet of the electrically driven compressor and at the other end to the inlet of the charge air cooler, and the electrically controlled check valve is designed to control the flow of charge air through the second section of the second airflow path.

[0017] The turbocharger can have a turbine with an inlet for receiving a supply of exhaust gas from the engine and an outlet for directing the exhaust gas into the atmosphere, and a bypass line is connected to a bypass flow control valve between a position upstream of the inlet to the turbine and a position downstream of the outlet of the turbine.

[0018] The bypass flow control valve can be an electrically controlled valve.

[0019] The system may also include an electronic control device for controlling the operation of the system.

[0020] The opening and closing of the electrically controlled shut-off valve and the opening and closing of the electrically controlled return valve can both be controlled by the electronic control unit.

[0021] The opening and closing of the bypass flow control valve can be controlled by the electronic control unit, and the electronic control unit can be configured to open the bypass flow control valve when a predefined limit value for exhaust pressure upstream of the turbine is reached.

[0022] Alternatively, the opening and closing of the bypass flow control valve can be controlled by the electronic control unit, and the electronic control unit can be configured to open the bypass flow control valve when a predefined turbine speed is reached.

[0023] The electrically operated compressor may have an electric motor controlled by the electronic control unit, and the electronic control unit may be configured to prevent the use of the electrically operated compressor when the bypass flow valve is in a closed state.

[0024] According to a second aspect of the invention, a motor vehicle is provided with a supercharger motor system constructed according to the first aspect.

[0025] According to a third aspect of the invention, a method for controlling a turbocharger system of a motor vehicle is provided, wherein the system comprises a motor, a variable geometry turbocharger dimensioned to meet the charge air requirement up to a predefined supply value, and an electrically operated compressor arranged in parallel to the turbocharger, wherein the motor is configured to receive a primary supply of charge air from the turbocharger during normal engine operation below the predefined supply value and to receive an additional supply of charge air from the electrically operated compressor when it is necessary to meet a temporary high charge air requirement above the predefined supply value, and includes a recirculation circuit to build up pressure when the electrically operated compressor starts up.before the electrically driven compressor is connected to the motor, the supercharger motor system further comprising a non-return valve to prevent backflow of air from an inlet to the electrically driven compressor, an electrically controlled shut-off valve for selectively isolating an outlet of the electrically driven compressor from the motor, and a recirculation circuit with an electrically controlled recirculation valve, the method comprising checking whether at least one condition for the use of the electrically driven compressor is present, and, if the at least one condition is present, activating the electrically driven compressor while the electrically controlled shut-off valve is held closed and the electrically controlled recirculation valve is held open to build up pressure in the recirculation circuit, and when the pressure in the recirculation circuit has reached a certain pressure,which is at least equal to the pressure of the primary charge air supply, the return valve is closed and the electrically controlled shut-off valve is opened to supply charge air to the engine.

[0026] One condition for using the electrically operated compressor may be a requirement by the driver of the motor vehicle for a torque greater than a predefined limit.

[0027] Alternatively, a condition for using the electrically operated compressor could be a current charge air requirement that is above the predefined supply value and therefore cannot be met solely by using the turbocharger.

[0028] Alternatively, there may be two conditions, both of which must be met for the electrically operated compressor to be activated, where the first condition may be a request for torque greater than a predefined limit by a driver of the motor vehicle, and the second condition may be an actual demand for charge air that is above the predefined supply value and therefore cannot be met solely by using the turbocharger.

[0029] The invention is described by way of example with reference to the accompanying drawings. These show: Fig. 1 a schematic diagram of a supercharger motor system according to a first aspect of the invention, Fig. 2 a schematic diagram of a motor vehicle according to a second aspect of the invention with a supercharger motor system according to the first aspect of the invention, Fig. 3a a higher-level flowchart of a method for controlling a charger motor system according to a third aspect of the invention, and Fig. 3b a number of sub-steps of a step of an electrically operated compressor of the in Fig. 3a shown procedure.

[0030] With particular reference to Fig. Figure 1 shows a turbocharger system 150 for a motor vehicle, comprising an internal combustion engine 105, a small-capacity variable-geometry turbocharger 120 dimensioned to meet the charge air requirement up to a predefined supply value, and an electrically driven compressor 130 arranged parallel to the turbocharger 120, comprising a compressor section 121 and an exhaust-driven turbine 122. Air is supplied to the compressor section 121 from the atmosphere, as indicated by the arrow 'a'.

[0031] The engine 105 is designed to receive a primary supply of charge air during normal engine operation below the predefined supply value from the turbocharger 120 and to receive an additional supply of charge air from the electrically operated compressor 130 when it is necessary to meet a temporary high demand for charge air above the predefined supply value.

[0032] A return circuit 102 is provided to build up pressure in the additional supply when the electrically operated compressor 130 starts up, before the electrically operated compressor 130 is connected to the motor 105.

[0033] The return circuit 102 includes an electrically controlled return valve 117 to direct the airflow through a line 119 that connects an outlet 134 of the electrically operated compressor 130 to an inlet 133 of the electrically operated compressor 130. An electrically controlled shut-off valve 116 is positioned between the outlet 134 of the electrically operated compressor 130 and the motor 105 to selectively disconnect the outlet 134 of the electrically operated compressor 130 from the motor 105.

[0034] A non-return valve 115 is provided to prevent the backflow of air from the inlet 133 to the electrically operated compressor 130 into the atmosphere, indicated by the arrow 'b'. The non-return valve 115 may comprise a check valve designed to prevent air from flowing back from the inlet 133 of the electrically operated compressor 130 into the atmosphere, or it may take the form of an electrically controlled non-return valve designed to close automatically if the pressure at the inlet 133 to the electrically operated compressor 130 is greater than atmospheric pressure, thus preventing air from flowing back from the inlet 133 of the electrically operated compressor 130 into the atmosphere.

[0035] When the electrically operated compressor 130 starts up, the electrically controlled return valve 117 is held open, and the electrically controlled shut-off valve 116 is held closed until the pressure in the return circuit 102 reaches a predefined pressure limit, which corresponds to a pressure value equal to or slightly greater than the pressure currently supplied to the engine 105 by the turbocharger 120. When the predefined pressure limit is reached, the electrically controlled shut-off valve 116 opens, and simultaneously the electrically controlled return valve 117 closes.

[0036] This arrangement prevents a sudden drop in pressure, which would occur if the electrically controlled shut-off valve 116 were to open when the electrically operated compressor 130 has not reached its speed or is switched off.

[0037] Therefore, there is a first flow path from the atmosphere 'aA' through the turbocharger 120 to the engine 105 and a second flow path from the atmosphere, indicated as arrow 'b', through the electrically operated compressor 130 parallel to the first flow path between a position upstream of the engine 105, indicated as point 'P', and a source of atmospheric air, indicated by the arrows 'a' and 'b'.

[0038] With particular reference to Fig. Figure 2 shows a motor vehicle 1 with a supercharger system 50. The main components of the supercharger system 50 are an internal combustion engine 5, which in this example is a four-cylinder in-line direct injection engine, a variable geometry turbocharger 20, an electrically driven compressor 30, and an electronic control unit 40.

[0039] Air enters an air inlet flow path from a source of atmospheric air, such as the atmosphere surrounding the engine 5, as shown by arrow 'A', and flows through an air filter 6 to a pair of parallel air flow paths.

[0040] The first airflow path has a first section 7, which connects the air filter 6 to an inlet of a compressor 21 of the turbocharger 20, and a second section 8, which connects an outlet of the compressor 21 of the turbocharger 20 to an inlet of an intercooler 9.

[0041] The second airflow path has a first section 13, which connects the air filter 6 to an inlet of a compressor part 31 of the electrically operated compressor 30, and a second section 14, which connects an outlet of the compressor part 31 of the electrically operated compressor 30 to an inlet of the charge air cooler 9.

[0042] It is understood that instead of a single air filter, two separate air filters can be used, one for the first airflow path and one for the second airflow path.

[0043] A non-return valve in the form of a check valve 15 is positioned in the second airflow path between the air filter 6 and the inlet width of the compressor part 31 to prevent backflow from the compressor part 31.

[0044] An electrically controlled shut-off valve 16 is positioned between the outlet of the compressor part 31 and the charge air cooler 14 to isolate the compressor part 31 of the electrically operated compressor 30 from the motor 5.

[0045] An electrically controlled return valve 17 is positioned in an air return circuit 19, which connects the outlet of compressor section 31 to the inlet of compressor section 31. The return circuit 19 is configured to connect the second section 14 of the second flow path to the inlet of compressor section 31 of the electrically driven compressor 30 at a position between the electrically controlled shut-off valve 16 and the outlet of compressor section 31 of the electrically driven compressor 30. The electrically controlled return valve 17 is used to optionally control the flow of charge air through the return circuit 19. When the electrically driven compressor 30 is not operating, the shut-off valve 16 is kept closed.

[0046] After cooling in the charge air cooler 9, the air flows via a throttle valve 10 to an intake manifold 11 of the engine 5 and through the engine 5, exiting the engine 5 via an exhaust pipe 11, which directs the exhaust gas to an inlet of a turbine 22 of the turbocharger 20. After flowing through the turbine 22 of the turbocharger 20, the exhaust gas flows from an outlet of the turbine 22 via an exhaust pipe 18 into the atmosphere, as indicated by the arrow 'E'. It is understood that various aftertreatment devices and sound damping devices are normally provided in the flow path from the turbine 22 back into the atmosphere.

[0047] A bypass line 26 is connected to the exhaust gas flow path between positions upstream and downstream of the turbine 22, thus allowing exhaust gas to selectively bypass the turbine 22 of the turbocharger 20. In this example, an electrically controlled bypass valve 25 is provided to direct the exhaust gas flow through the bypass line 26. The opening and closing of the bypass valve 25 are controlled by the electronic control unit 40. However, it is understood that a pressure-operated bypass valve can also be used instead of an electrically controlled bypass valve. In this case, a sensor would be used to provide information about whether the bypass valve is open or closed.

[0048] The electrically operated compressor 30 has an electric motor 32 for driving the compressor part 31 in response to a control signal from the electronic control unit 40.

[0049] The electronic control unit 40 is designed to control the opening and closing of the electrically controlled shut-off valve 16, the electrically controlled return valve 17 and the electrically controlled bypass valve 26 and the operation of the electric motor 32 according to predefined control routines stored in the electronic control unit 40.

[0050] The electronic control unit 40 can also be configured to control the fuel supply to the engine, or can be part of a powertrain control system performing such a function.

[0051] The electronic control unit 40 receives a number of inputs which are collectively referred to as a single input 45 in Fig. 1 are shown. The inputs 45 include those representing the operation of the engine 5, such as engine speed, intake manifold pressure, exhaust pressure upstream of the turbine 22, throttle position, as well as inputs representing other system parameters, such as air pressure downstream of the turbocharger compressor, air pressure in the recirculation circuit 19, air pressure downstream of the compressor section 31 of the electrically driven compressor 30.

[0052] In addition to the inputs 45, the electronic control unit 40 also receives an input indicating a request from the driver from an accelerator pedal position sensor 42, which is designed to detect the angular position of an accelerator pedal 43 of the motor vehicle 1.

[0053] The electronic control unit 40 is designed to control the operation of the motor system 50, of which it is a part, using the inputs 45 and 42.

[0054] The operation of the engine system 50 is as follows.

[0055] When the motor 5 is running normally, the electric motor 32 of the electrically operated compressor 30 is switched off, and the electrically controlled shut-off valve 16 and the bypass valve 25 are both in a closed state by the electronic control device 40.

[0056] Air entering the air intake flow path therefore flows from the air filter 6 through the first section 7, which connects the air filter 6 to the air intake side of a compressor 21 of the turbocharger 20, where it is compressed, and then flows via the second section 8 of the air path to the inlet of the charge air cooler 9 and from there via the throttle valve 10 to the engine 5. No air flows from the electrically driven compressor 30, since the electric motor 32 is switched off and the compressor 30 is separated from the engine 5 by the closed, electrically controlled shut-off valve 16, which is kept closed when the electrically driven compressor 30 is not operating.

[0057] In this state, the engine 5 acts as a conventional turbocharged engine with a variable geometry turbocharger, the geometry of the turbocharger 20 being adjusted by the electronic control unit 40 to match variations in the driver's requirements as detected by the accelerator pedal position sensor 42.

[0058] Therefore, the electrically driven compressor 30 places no electrical demand on the vehicle's electrical generation or storage systems 1, as it is not operating. The variable geometry turbocharger 20 is dimensioned to provide sufficient boost pressure to meet normal operating needs, such as highway driving, driving at a constant speed in the city, and moderate acceleration. By using a relatively small variable geometry turbocharger 20, the turbocharger 20 responds very well to demands at low engine speeds, thus minimizing turbo lag.

[0059] It is understood that as the engine speed 5 increases, the exhaust gas flow from the engine 5, at large throttle openings, will eventually reach a level where excessive backpressure is generated by the turbine 22 of the turbocharger 20 due to its small size, and / or the volume of the exhaust gas flow to the turbine 22 is such that overspeeding of the turbocharger 20 is caused. To prevent these events from occurring, the bypass valve 25 is opened by the electronic control unit 40 when a predefined limit for the exhaust gas pressure upstream of the turbine 22 is reached and / or a predefined turbine speed is reached. The opening of the bypass valve 25 has the effect of allowing a portion of the exhaust gas to bypass the turbine 22 of the turbocharger 20, thereby reducing the exhaust backpressure on the engine 5.However, because of the volume of exhaust gas that can now bypass the turbine 22, it has the effect of limiting the boost pressure that can be supplied by the turbocharger 20 when operating above such a high exhaust flow, and thus no further temporary demand for more power by the driver can be met by the small turbocharger 20 alone.

[0060] To overcome this limitation, the electrically operated compressor 30 is used to meet any further temporary request from the driver when the bypass valve 25 is open.

[0061] Therefore, if the driver demand, as detected by the accelerator pedal position sensor 42, exceeds a predefined demand threshold when the bypass valve 25 is open, the electronic control unit 40 is configured to open the return valve 17 and switch on the electric motor 32, causing the compressor section 31 to increase the air pressure in the return circuit 19. In a non-restrictive example, a driver demand of 75% was used as the predefined demand threshold. It is understood that, due to the presence of the check valve 15 in the first section 13 of the second airflow path and the closed, electrically controlled shut-off valve 16 in the second section 14 of the second airflow path, air cannot flow back to the air filter 6.

[0062] When the pressure in the return circuit 19 reaches or exceeds the pressure in the second section 8 of the air path to the inlet of the charge air cooler 9, that is, the current pressure of the charge air supplied by the turbocharger 20, the electrically controlled shut-off valve 16 opens, and simultaneously the return valve 17 closes. Due to the large pumping capacity of the compressor section 31 of the electrically driven compressor 30, the delay between the activation of the electric motor 32 and the opening of the electrically controlled shut-off valve 16 is minimal and typically on the order of a few tenths of a second.

[0063] Ambient air now flows from the air filter 6 through the first section 13 of the second airflow path to the compressor section 31 of the electrically driven compressor 30 and via the second section 14 of the second airflow path over the charge air cooler 9 to the engine 5, just as it flows from the air filter 6 through the first section 7 of the first airflow path to the compressor 21 of the turbocharger 20 and via the second section 8 of the first airflow path over the charge air cooler 9 to the engine 5. That is, the electrically driven compressor 30 acts as a supplement to the turbocharger 20.

[0064] The compressor section 31 of the electrically driven compressor 30 is dimensioned such that it is capable of supplying sufficient additional compressed air at the desired maximum boost pressure to the motor 5 to meet the motor's maximum requirement at its maximum operating speed. Although this necessitates the use of a large-capacity compressor section 31, which draws a significant amount of power from the vehicle 1's electrical system, this power draw occurs only for a very short period.For example, it may be necessary for the electric motor 32 to draw 25 kW of power from the electrical system of the motor vehicle 1 when operating the compressor part 31 of the electrically operated compressor 30. However, since the electrically operated compressor 30 is only used to meet temporary high power requirements, such as almost full throttle opening at higher engine speeds, the electrically operated compressor 30 only operates for a very short period of time, such as 15 to 20 seconds, and thus the total draw of electrical energy from the electrical system of the motor vehicle 1 is not excessively large.

[0065] To prevent excessive electrical power consumption, the electronic control unit 40 is designed to prevent the electrically driven compressor 30 from operating continuously for extended periods, and after a predefined period, the power supply to the electric motor 32 is automatically switched off. The electrically driven compressor 30 is therefore designed to operate as an overboost device in situations where the boost pressure available from the small turbocharger is insufficient and is not used during normal engine operation.

[0066] As soon as the driver's demand falls below the predefined demand threshold, as indicated by the output of the accelerator pedal position sensor 42, the electronic control unit 40 switches off the electric motor 32 and closes the electrically controlled shut-off valve 16, thus disconnecting the compressor section 31 of the electrically driven compressor 30 from the motor 5. The operation of the motor 5 then reverts to using the turbocharger 20 alone, which, at such demand levels, is capable of meeting any boost pressure requirements of the motor 5.

[0067] In summary, the electrically operated compressor 30 is therefore only used to meet a temporary peak power requirement that cannot be met by the turbocharger 20 alone, and is not used during the normal operation of the engine 5, since in this case the requirement is met solely by using the small-sized, variable-geometry turbocharger 20.

[0068] With reference to Fig. 3a and Fig. 3b shows a method 200 for controlling a supercharger motor system of a motor vehicle, such as the system 50 with a motor, a turbocharger and an electrically operated compressor.

[0069] The procedure begins in block 210, which represents a start-up state and an engine start-up process, and then proceeds to block 220, where the engine is running and responding to power demands from a vehicle user. In block 230, it is checked whether the conditions for using the electrically driven compressor are met. In this embodiment, these conditions include whether a torque demand from the vehicle is greater than a predefined limit, as indicated by the output of the accelerator pedal 42, and whether the turbocharger is already operating in a bypass state, as indicated by an open state of the bypass valve 25. That is, can the turbocharger meet any further engine torque demands from the driver?

[0070] If the conditions for using the electrically driven compressor are not met, the procedure proceeds to Block 240, where the turbocharger is used to supply charge air to the engine to meet a current request from the vehicle's driver. In most circumstances, this is the case, as the turbocharger is sized to meet most of the engine's needs, with the exception of very high torque demands at high engine speeds.

[0071] From block 240, the procedure proceeds to block 260 to check if a shutdown has taken place and, if so, proceeds to block 290 where it ends, but otherwise it returns to block 230 and goes through blocks 230, 240 and 260 until one of the conditions for using the electrically driven compressor is met or a shutdown has taken place.

[0072] Returning to Block 230, if the conditions for using the electrically driven compressor are met, as verified in Block 230, the procedure then proceeds from Block 230 to Block 250, where the electrically driven compressor is used to supply additional charge air to the engine.

[0073] From block 250, the procedure proceeds to block 260 to check whether a shutdown has occurred. If so, it continues to block 290, where it ends. Otherwise, it returns to block 230 and repeats blocks 230, 250, and 260 until one of the conditions for using the electrically driven compressor no longer exists or a shutdown has occurred. One of the conditions that may be checked in block 230 is whether the electrically driven compressor is already running and whether it has run for longer than a predefined period. If it has run for longer than a predefined period, this can be taken as an indication that the conditions for using the electrically driven compressor are not met.

[0074] As in Fig.As shown in Figure 3b, block 250 in this example comprises a number of sub-steps, shown in block 252 as activating or switching on the electric motor used to drive the electrically operated compressor, in block 254 as building up pressure in a return circuit to prevent interruptions in the supply of charge air to the engine, and in block 256 as checking whether the available pressure of the electrically operated compressor (the pressure P) RC in the return circuit) at least equal to the pressure (P TCO ) in the air supply from the turbocharger, and in block 258, if it was found in block 256 that the pressure P RC at least equal to the pressure P TCO The air supply from the turbocharger is the connection of the electrically operated compressor to an intake manifold of the engine.

[0075] Therefore, the procedure can be implemented such that the electrically operated compressor is only used to supply boost pressure to the engine when predefined conditions are present, and at all other times the turbocharger is designed to supply charge air to the engine.

[0076] Through careful analysis of real engine operation, the inventors have found that the performance requirements of an engine during most operating situations can be met by using a conventional, small-sized variable geometry turbocharger that is capable of meeting normal performance requirements but provides excellent low-speed response to sudden torque demands.

[0077] For example, a mid-range hatchback often only needs 40 kW to drive at a constant speed of 100 km / h, but is equipped with an engine with more than 80 kW.

[0078] Furthermore, during normal use, many drivers rarely utilize more than 50% of the available power, and some seldom exceed 30%. Only when high power is required, for example to perform an overtaking maneuver, is such a small turbocharger unable to meet this demand.

[0079] Therefore, by using an electrically driven compressor to meet such high, short-term power demands, while the small turbocharger fulfills all other requirements, a more responsive and potentially more effective turbocharger-motor system is created. Providing a recirculation circuit for the electrically driven compressor is a simple and relatively easy way to reduce air pressure fluctuations when the electrically driven compressor is activated to increase the charge air supply from the turbocharger.By using the electrically operated compressor only when it is necessary to increase the supply of charge air from the turbocharger, and then only for short periods of high demand, the electrical load on the battery of the motor vehicle to which the engine system is attached is reduced, thereby reducing the risk of the motor vehicle battery being dangerously discharged and avoiding the need for additional fuel to subsequently recharge the battery.

[0080] It is understood that, although the invention has been described with reference to a multi-cylinder in-line engine, it is not limited to such use and can be used, for example, for a single-cylinder engine or for engines with a number of cylinders arranged in cylinder banks, such as V6 or V8 engines.

[0081] It is understood by those skilled in the art that, although the invention has been described by way of example with reference to one or more embodiments, it is not limited to the disclosed embodiments, and that alternative embodiments can be constructed without deviating from the scope of protection of the invention, as defined by the attached claims.

Claims

[1] Supercharger motor system for a motor vehicle, comprising: an internal combustion engine, a small-capacity, variable-geometry turbocharger designed to meet the charge air requirement up to a predefined supply value, and an electrically driven compressor arranged in parallel to the turbocharger, which is operated by an electronic control unit, wherein the engine is configured to receive a primary supply of charge air during normal engine operation below the predefined supply value from the turbocharger and to receive an additional supply of charge air from the electrically driven compressor when it is necessary to meet a temporary high demand for charge air above the predefined supply value, and a recirculation circuit to build up pressure when the electrically driven compressor starts up before the electrically driven compressor is connected to the engine, wherein the recirculation circuit includes an electrically controlled recirculation valve for directing the airflow through a duct connecting an outlet of the electrically driven compressor to an inlet of the electrically driven compressor.An electrically controlled shut-off valve positioned between the outlet of the electrically driven compressor and the motor for selectively isolating the outlet of the electrically driven compressor from the motor, and a non-return valve to prevent backflow of air from the inlet of the electrically driven compressor into the atmosphere, wherein the electronic control unit is configured to, Keeping the electrically controlled return valve open and the electrically controlled shut-off valve closed when the electrically operated compressor starts up, until the pressure in the return circuit reaches a predefined limit value, and in response to reaching the predefined limit value, opening the electrically controlled shut-off valve and closing the electrically controlled return valve. [2] System according to claim 1, wherein the non-return valve is a check valve designed to prevent the flow of air from the inlet of the electrically operated compressor back into the atmosphere. [3] System according to claim 1, wherein the non-return valve is an electrically controlled non-return valve configured to close automatically if the pressure at the inlet of the electrically operated compressor is greater than atmospheric pressure, in order to prevent the flow of air from the inlet of the electrically operated compressor back into the atmosphere. [4] System according to one of claims 1 to 3, wherein a first flow path from the atmosphere through the turbocharger to the engine and a second flow path arranged parallel to the first flow path from the atmosphere through the electrically operated compressor between a position upstream of the engine and a source of atmospheric air are provided. [5] System according to claim 4, wherein the position upstream of the engine is an inlet to a charge air cooler with an outlet configured to direct air to the engine, wherein the system further comprises an air filter through which all air for the engine flows from the source of atmospheric air, and wherein the first and second air flow paths each have a low-pressure end connected to an outlet from the air filter. [6] System according to claim 5, wherein the first flow path has a first section which is connected at one end to the air filter and at a second end to an inlet of a compressor of the turbocharger, and a second section which is connected at one end to an outlet of the compressor of the turbocharger and at a second end to the inlet of the charge air cooler, and wherein the second air flow path has a first section with the check valve which is connected at one end to the air filter and at a second end to the inlet of the electrically driven compressor, and a second section which is connected at one end to the outlet of the electrically driven compressor and at a second end to the inlet of the charge air cooler, and wherein the electrically controlled check valve is configured toto control the flow of charge air through the second section of the second flow path. [7] System according to any one of claims 1 to 6, wherein the turbocharger has a turbine with an inlet for receiving a supply of exhaust gas from the engine, an outlet for directing the exhaust gas into the atmosphere, and wherein a bypass line is connected with a bypass flow control valve between a position upstream of the inlet to the turbine and a position downstream of the outlet of the turbine. [8] System according to claim 7, wherein the bypass flow control valve is an electrically controlled valve. [9] System according to one of the preceding claims, wherein the opening and closing of the electrically controlled shut-off valve and the opening and closing of the electrically controlled return valve are both controlled by the electronic control device. [10] System according to claim 8, wherein the opening and closing of the bypass flow control valve is controlled by the electronic control device, and the electronic control device is configured to open the bypass flow control valve when a predefined limit value for the exhaust pressure upstream of the turbine is reached. [11] System according to claim 8, wherein the opening and closing of the bypass flow control valve is controlled by the electronic control device, and wherein the electronic control device is configured to open the bypass flow control valve when a predefined rotational speed of the turbine is reached. [12] System according to claim 10 or claim 11, wherein the electronic control device is configured to prevent the use of the electrically operated compressor when a bypass flow control valve is in a closed state. [13] A method for controlling a turbocharger motor system of a motor vehicle, the system comprising an engine, a variable geometry turbocharger sized to meet the charge air demand up to a predefined supply value, an electrically driven compressor controlled by an electrical control unit, the electrically driven compressor arranged in parallel with the turbocharger, the engine configured to receive a primary charge air supply from the turbocharger during normal engine operation below the predefined supply value and to receive an additional charge air supply from the electrically driven compressor when it is necessary to meet a temporary high charge air demand above the predefined supply value, and a recirculation circuit to build up pressure when the electrically driven compressor starts up.before the electrically driven compressor is connected to the motor, the supercharger motor system further comprising a non-return valve to prevent backflow of air from an inlet of the electrically driven compressor to the atmosphere, and an electrically controlled shut-off valve for selectively isolating an outlet of the electrically driven compressor from the motor, the recirculation circuit comprising an electrically controlled recirculation valve, the method comprising checking whether at least one condition for the use of the electrically driven compressor is present, and, if the at least one condition is present, activating the electrically driven compressor while the electrically controlled shut-off valve is held closed and the electrically controlled recirculation valve is held open to build up pressure in the recirculation circuit, and when the pressure in the recirculation circuit has reached a certain pressure,which is at least equal to the pressure of the primary charge air supply, the electrically controlled return valve is closed and the electrically controlled shut-off valve is opened to supply charge air to the engine. [14] Method according to claim 13, wherein a condition for using the electrically operated compressor is a request by a driver of the motor vehicle for a torque greater than a predefined limit. [15] Method according to claim 13, wherein a condition for using the electrically operated compressor is a current demand for charge air that is above the predefined supply value and therefore cannot be met solely by using the turbocharger. [16] Method according to claim 13, wherein two conditions are present, both of which must be met in order for the electrically operated compressor to be activated, wherein the first condition is a request by a driver of the motor vehicle for a torque greater than a predefined limit value, and the second condition is an actual request for charge air which is above the predefined supply value and which therefore cannot be met by using the turbocharger alone.

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