Patent ID: 12215638

DETAILED DESCRIPTION

Aspects and/or embodiments of the 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.1illustrates embodiments of a vehicle2configured for land-based propulsion. The vehicle2comprises a compression ignition four-stroke internal combustion engine, ICE,4according to aspects and/or embodiments discussed herein, such as e.g. the ICE discussed below with reference toFIG.2. The ICE4comprises a control arrangement, as discussed below with reference toFIGS.2and3.

In these embodiments, the vehicle2is a heavy load vehicle in the form of a truck. Although the invention is not limited to any particular type of vehicle, the invention is particularly relevant for vehicles for land-based propulsion comprising larger compression ignition ICEs, such as also e.g. busses or construction vehicles.

FIG.2schematically illustrates embodiments of an ICE4. The ICE4may be configured to form part of a powertrain of a vehicle, such as e.g. the vehicle2shown inFIG.1.

The ICE4is a compression ignition four-stroke direct injection internal combustion engine, e.g. a diesel engine. The ICE4comprises at least one cylinder arrangement6, a crankshaft8, an exhaust camshaft10, an intake camshaft12.

The cylinder arrangement6comprises a combustion chamber14, a cylinder bore16, a piston18configured to reciprocate in the cylinder bore16, an exhaust valve20, and an intake valve22. The piston18is connected to the crankshaft8via a connecting rod24.

The movement of the exhaust valve20is controlled by the exhaust camshaft10, i.e. the exhaust camshaft10is configured to control the opening and closing of the exhaust valve20. The movement of the intake valve22is controlled by the intake camshaft12, i.e. the intake camshaft12is configured to control the opening and closing of the intake valve22.

The intake valve22is configured for admitting charge air into the combustion chamber14, and the exhaust valve20is configured for letting exhaust gas out of the combustion chamber14. The timing of the exhaust camshaft10is configured to the be controlled by a timing control arrangement30as indicated by a double arrow. Similarly, the timing of the intake camshaft12is configured to the be controlled by a timing control arrangement32as indicated by a double arrow.

In a known manner, the intake valve22comprises an intake valve head configured to seal against an intake valve seat extending around an intake opening26. Similarly, the exhaust valve20comprises an exhaust valve head configured to seal against an exhaust valve seat extending around an exhaust opening28.

In a known manner, the camshafts10,12may rotate at half the rotational speed of the crankshaft8and control the movement of the exhaust and intake valves20,22via cam lobes40,42arranged on the camshafts10,12. The exhaust camshaft10is arranged for controlling movement of the exhaust valve20, and opening and closing of the exhaust opening28. The exhaust camshaft10comprises a cam lobe40. For instance, by abutting against the cam lobe40, the exhaust valve20will follow a contour of the cam lobe40. The exhaust valve20may be biased towards its closed position, e.g. by means of a non-shown spring. The movement of the intake valve22is controlled in a corresponding manner by the intake camshaft12and its cam lobe42for opening and closing the intake opening26.

The piston18is arranged to reciprocate in the cylinder bore16. The piston18performs four strokes in the cylinder bore16, corresponding to an intake stroke, a compression stroke, an expansion or power stroke, and an exhaust stroke, see alsoFIG.4. InFIG.2the piston18is illustrated with continuous lines at its Bottom Dead Centre, BDC, and with dashed lines at its Top Dead Centre, TDC. The combustion chamber14is formed above the piston18inside the cylinder bore16.

The cylinder arrangement6has a total swept volume, Vs, in the cylinder bore16between the BDC and the TDC. According to some embodiments, the cylinder arrangement6may have a total swept volume, Vs, of within a range of 0.25 to 4 litres or within a range of 1 to 4 litres.

The ICE4may comprise more than one cylinder arrangement6, such as e.g. three, four, five, six, or eight cylinder arrangements6. Mentioned purely as an example, the total swept volume of the ICE4, i.e. the sum of the swept volumes Vs of the cylinder arrangements of the ICE4, may be within a range of 1-20 litres, or within a range of 5-20 litres.

The ICE4comprises a turbocharger44. The turbocharger44comprises a compressor50and a turbine52. The compressor50and the turbine52of the turbocharger44are connected via a common shaft54. An inlet conduit46for charge air, leads from the compressor50to the intake opening26. For the sake of clarity, the inlet conduit46is not shown in its entirety. An exhaust conduit48leads from the exhaust opening28to the turbine52. The turbocharger44produces a charge air pressure in the inlet conduit46and at the intake valve22. More specifically, the gas discharged via the exhaust valve20drives the turbine52, which in turn rotates the compressor50. Thus, the compressor50provides charge air a to the intake valve22.

The ICE4comprises a fuel injector56configured for injecting fuel into the combustion chamber14when the ICE4produces positive torque during power strokes of the piston18, e.g. for propelling the vehicle2.

The ICE4further comprises a control arrangement38according to aspects and/or embodiments discussed herein. The control arrangement38is configured for controlling variable valve timing of the ICE4. That is, the control arrangement38is configured for controlling at least the timing of the exhaust camshaft10and the timing of the intake camshaft12. Accordingly, the timing control arrangements30,32form part of the control arrangement38.

In order to reduce vibrations of the ICE4, the control arrangement38is configured to, when operating the ICE4below a threshold rotational speed:change a timing of the exhaust camshaft10to advance closing of the exhaust valve20, andchange a timing of the intake camshaft12to delay opening of the intake valve22.

In addition to the threshold rotational speed, further conditions may apply for the timing changes of the camshafts10,12to be performed. Such further conditions may relate to ICE vibration level, vehicle speed, and/or vehicle position, as discussed herein.

According to embodiments, the threshold rotational speed may be a rotational speed ω within a range of 1-1000 rpm. In this manner, the threshold rotational speed of the engine4may be delimited at a rotational speed, below which excessive engine vibrations occur.

The threshold rotational speed of the ICE4may be different for different conditions. For instance, if the rotational speed of the ICE4is the sole condition for performing the timing changes of the crankshafts10,12, a first threshold rotational speed may apply. If the condition includes the rotational speed of the ICE4and a further condition such as e.g. the vehicle speed, a second threshold rotational speed, different from the first threshold rotational speed, may apply.

The particular threshold speed may depend on the particular ICE, its size, number of cylinders etc. and the suspension of the ICE in the vehicle or other structure. The suspension of a cabin of the vehicle may affect which vibrations could be transferred to the driver and/or passengers of the vehicle and thus, may also influence the choice of threshold speed or speeds.

The control arrangement38comprises a rotational speed sensor75for sensing the rotational speed of the crankshaft8of the ICE4.

The control arrangement38and the timing changes of the camshafts10,12are further discussed below with reference toFIGS.3-6.

FIG.3illustrates a control arrangement38to be utilised in connection with various aspects and/or embodiments of the invention. In particular, the control arrangement38is configured for the control of the timing of the camshafts10,12of the ICE4discussed in connection withFIGS.1and2. The control arrangement38is also indicated inFIG.2. The control arrangement38and engine4may be provided in a vehicle2. Accordingly, in the following reference is made toFIGS.1-3.

The control arrangement38comprises at least one calculation unit60, which may take the form of substantially any suitable type of processor circuit or microcomputer, e.g. a circuit for digital signal processing (digital signal processor, DSP), a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions. The herein utilised expression “calculation unit” may represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above. The calculation unit60may be configured to perform calculations, such as e.g. analysing accelerometer data and/or rotational speed sensor measurements as discussed herein. The calculation unit60may be configured to compare GPS data with map data. The calculation unit60may be configured to compare measured or calculated data with threshold values.

The control arrangement38comprises a memory unit62. The calculation unit60is connected to the memory unit62, which provides the calculation unit60with, e.g. stored programme code, data tables, and/or other stored data which the calculation unit60needs to enable it to do calculations and to control the ICE. The calculation unit60is also adapted to store partial and/or final results of calculations in the memory unit62. The memory unit62may comprise a physical device utilised to store data or programs, i.e. sequences of instructions on a temporary or permanent basis. According to some embodiments, the memory unit62may comprise integrated circuits comprising silicon-based transistors. The memory unit62may comprise e.g. a memory card, a flash memory, a USB memory, a hard disc, or another similar volatile or non-volatile storage unit for storing data such as e.g. ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), EEPROM (Electrically Erasable PROM), etc. in different embodiments.

The control arrangement38is further provided with respective devices70,71,72,66,68for receiving and/or sending input and output signals. These input and output signals may comprise waveforms, pulses or other attributes, which can be detect as information by signal receiving devices, and which can be converted to signals processable by the calculation unit60. Input signals are supplied to the calculation unit60from the input receiving devices70,71,72. Output signal sending devices66,68are arranged to convert calculation results from the calculation unit60to output signals for conveying to signal receiving devices of other parts of the control arrangement38. Each of the connections to the respective devices for receiving and sending input and output signals may take the form of one or more from among a cable, a data bus, e.g. a CAN (controller area network) bus, a MOST (media orientated systems transport) bus or some other bus configuration, or a wireless connection. In the embodiment depicted, only one calculation unit60and memory unit62are shown, but the control arrangement38may alternatively comprise more than one calculation unit and/or memory unit.

Mentioned as examples, the output signal sending devices66,68, may send control signals to the timing control arrangements30,32of the exhaust and intake camshafts10,12. The input signal receiving devices70,71,72may receive signals from the ICE4, such as e.g. from a rotational speed sensor75of the crankshaft8of the ICE4, a vibration sensor76, and a vehicle position sensor78.

Examples of data tables may be e.g.;a table containing accelerometer measurement and engine vibration level concordance,a table containing timing change angles of the exhaust and intake camshafts10,12at specific engine rotational speeds of the ICE4,a table containing ICE rotational speed irregularities and their concordance with vibrations,a table containing timing change angles of the exhaust and intake camshafts10,12at different vibration levels,tables containing map data e.g. related to city areas and/or noise restriction areas,

Examples of data may be measured, monitored, determined, and/or calculated data, such as rotational speed data, engine vibration data, timing change angle data. The control arrangement38comprises or is connected to various sensors and actuators in order to receive input and provide output for performing the various aspects and embodiments of the method discussed herein. Some of the various sensors are exemplified above. An example of actuators may be actuators configured for changing the timing of the camshafts10,12and forming part of the timing control arrangements30,32.

The control arrangement38may be configured to perform a method100according to any one of aspects and/or embodiments discussed herein, see e.g. below with reference toFIG.5.

As mentioned above, when operating the ICE4below a threshold rotational speed, the control arrangement38is configured to:change a timing of the exhaust camshaft10to advance closing of the exhaust valve20, andchange a timing of the intake camshaft12to delay opening of the intake valve22.

Herein, reference is made to crankshaft angle degrees, CA degrees, e.g. when discussing timing changes of the camshafts. One full rotation of the crankshaft is 360 CA degrees. Crankshaft angle may be measured e.g. from Top Dead Centre fire, TDCfire, or Top Dead Centre gas exchange, TDCge. Negative timing change angles related to advancing the opening and closing of a relevant valve and positive timing change angles related to delaying the opening and closing of a relevant valve.

An overlap between the exhaust and intake valves means that the exhaust and intake valves are open simultaneously at TDCge. A negative overlap between the exhaust and intake valves means that the exhaust and intake valves are not open simultaneously at TDCge. According to embodiments, the control arrangement38may comprise a sensor75,76configured to sense vibrations of the ICE4. The control arrangement38may be configured to, when operating the internal combustion engine (4) below the threshold rotational speed and in response to sensed vibrations exceeding a threshold level: change the timing of the exhaust camshaft10to advance closing of the exhaust valve20, and change the timing of the intake camshaft12to delay opening of the intake valve22. In this manner, in addition to the rotational speed of the ICE4, the information provided by the sensor75,76configured to sense vibrations of the ICE4may be utilised for reducing vibrations of the engine4with the timing changes of the exhaust and intake camshafts10,12.

The sensor configured to sense vibrations of the ICE4may for instance be an accelerometer76mounted on the engine4or close to the engine4in a manner such that the accelerometer76is affected by engine vibrations. The calculation unit60may be configured to evaluate the signal from the accelerometer76in order to establish a magnitude of the engine vibrations. According to an alternative embodiment, the sensor configured to sense vibrations of the engine4may comprise the rotational speed sensor75of the engine4. The rotational speed sensor75forms part of an ordinarily control system of the ICE4. Such a rotational speed sensor75may for instance be a Hall effect sensor which is arranged to provide a large number of pulses during one rotation of the crankshaft8. Based on the pulses, the calculation unit60may determine rotational speed irregularities/variations of the rotational speed ω of the crankshaft8. Certain rotational speed irregularities/variations may be identified as engine vibrations, or may cause engine vibrations, above the threshold level.

According to embodiments wherein the control arrangement38is arranged in a vehicle2, the control arrangement38may be configured to determine whether the vehicle2is propelled at a speed below a threshold speed. When operating the internal combustion engine4below the threshold rotational speed and in response to the vehicle2being propelled at a speed below the threshold speed, the control arrangement38may be configured to change the timing of the exhaust camshaft10to advance closing of the exhaust valve20, and change the timing of the intake camshaft12to delay opening of the intake valve22. In this manner, not only the rotational speed of the engine4but also the vehicle speed may determine whether the timings of the exhaust and intake camshafts10,12are changed. Namely, certain combinations of engine rotational speed and vehicle speed may cause excessive engine vibrations.

According to embodiments wherein the control arrangement38is arranged in a vehicle2, the vehicle2may comprise a positioning system78, such as a GPS system. The control arrangement38may be configured to determine a position of the vehicle2. When operating the internal combustion engine4below the threshold rotational speed and in response to the position of the vehicle2being determined to be within an area of a particularly defined type, the control arrangement38may be configured to: change the timing of the exhaust camshaft10to advance closing of the exhaust valve20, and change the timing of the intake camshaft12to delay opening of the intake valve22. In this manner, not only the rotational speed of the engine4but also the position of the vehicle may determine whether the timings of the exhaust and intake camshafts10,12are changed. Namely, the area of a particularly defined type may relate to certain geographical areas, wherein excessive vehicle noise may be prohibited. In such areas, the reduction of engine vibrations may be beneficial from a vehicle noise reduction perspective.

FIG.4illustrates diagrams over the ICE4ofFIG.2, and control thereof in accordance with the discussion above with reference toFIGS.1-3. Accordingly, in the following reference is also made toFIGS.1-3.FIG.4illustrates the four strokes of a piston18and the movements of the exhaust valve20(broken line) and of the intake valve22(dash-dotted line) during operation of the ICE4. The crankshaft8of the ICE4rotates 720 degrees CA as the four strokes of the piston18are performed. For each stroke, the crankshaft8rotates 180 degrees CA as indicated inFIG.4. The full line indicates the pressure within the combustion chamber14of the ICE4.

Along line I. the opening and closing of the exhaust and intake valves20,22are shown during ordinary combustion in the ICE4without variable valve timing applied. The exhaust valve20and the intake valve22are opened and closed in an ordinary manner during the respective exhaust and intake strokes, before and after TDCge.

Along line II. the opening and closing of the exhaust and intake valves20,22are shown with variable valve timing applied in order to reduce engine vibrations when the engine4is operated below a threshold rotational speed. The control arrangement38is configured to change the timing of the exhaust camshaft10to advance closing of the exhaust valve20and to change the timing of the intake camshaft12to delay opening of the intake valve22.

The pressure within the combustion chamber14at TDCfire is lower than during ordinary combustion, due to the intake valve12closing later and the exhaust valve10opening earlier. Also, due to the early closing of the exhaust valve10and the late opening of the intake valve12, a pressure is built up in the combustion chamber14at TDCge. According to embodiments of the control arrangement38and of the internal combustion engine4, an absolute value of a timing change angle α of the exhaust camshaft10during the change of the timing of the exhaust camshaft10and an absolute value of a timing change angle β of the intake camshaft12during change of the timing of the intake camshaft12may be the same. In this manner, symmetrical timing changes of the exhaust and intake camshafts may be provided. The timing changes may be symmetrical about TDCge.

According to embodiments of the control arrangement38and of the internal combustion engine4, the timing change angle α of the exhaust camshaft10to advance closing of the exhaust valve20may be at least within a range of −5 to −80 degrees CA or within a range of −10 to −80 degrees CA, and the timing change angle β of the intake camshaft12to delay opening of the intake valve22may be at least within a range of 5-80 degrees CA or within a range of 10 to 80 degrees CA. In this manner, there may be provided timing change angles α,β, which achieve reduction of engine vibrations.

For instance, timing change angles of up to −60 degrees CA and 60 degrees CA, respectively, may be provided during driving operation of the ICE4, i.e. when fuel is injected into the combustion chamber14and combusted around TDCfire, in order to reduce engine vibrations at low ICE rotational speeds. During motoring of the ICE, i.e. when no fuel is injected into the combustion chamber14and the crankshaft8of the ICE is driven by a rotation of the wheels of the vehicle, timing change angles of up to −80 degrees CA and 80 degrees CA, respectively, may be provided in order to reduce vibrations at low ICE rotational speeds.

FIG.5illustrates embodiments of a method100for vibration reduction in a compression ignition four-stroke internal combustion engine4, when operating the ICE4below a threshold rotational speed, the method100comprise steps of:changing102a timing of the exhaust camshaft10to advance closing of the exhaust valve20, andchanging104a timing of the intake camshaft12to delay opening of the intake valve22.

Embodiments of the control arrangement38discussed above are applicable in a corresponding manner in the method100.

According to embodiments, the threshold rotational speed may be a rotational speed within a range of 1-1000 rpm.

According to embodiments, preceding the steps of changing102the timing of the exhaust camshaft10and changing104the timing of the intake camshaft12, the method100may comprise a step of:sensing106vibrations of the internal combustion engine, and wherein in response to sensed vibrations exceeding a threshold level the steps of changing102the timing of the exhaust camshaft10and changing104the timing of the intake camshaft12may be performed.

According to embodiments, the method100may be performed in a vehicle2configured for land-based propulsion.

According to embodiments, preceding the steps of changing102the timing of the exhaust camshaft10and changing104the timing of the intake camshaft12, the method100may comprise a step of:determining108whether the vehicle2is propelled at a speed below a threshold speed, and wherein in response to the vehicle2being propelled at a speed below the threshold speed the steps of changing102the timing of the exhaust camshaft10and changing104the timing of the intake camshaft12are performed.

According to embodiments, the vehicle2may comprise a positioning system78, such as a GPS system, and wherein preceding the steps of changing102the timing of the exhaust camshaft10and changing104the timing of the intake camshaft12, the method100may comprise a step of:determining110a position of the vehicle2, and wherein in response to the position of the vehicle2being determined to be within an area of a particularly defined type the steps of changing102the timing of the exhaust camshaft10and changing112the timing of the intake camshaft12are performed.

According to a further aspect, there is provided a computer program comprising instructions which, when the program is executed by a computer, causes the computer to carry out a method100according to any one of aspects and/or embodiments discussed herein.

One skilled in the art will appreciate that the method100of controlling timings of an exhaust camshaft10and an intake camshaft12of a four-stroke ICE4may be implemented by programmed instructions. These programmed instructions are typically constituted by a computer program, which, when it is executed in a computer or calculation unit60, ensures that the computer or calculation unit60carries out the desired control, such as the method100, and thereto related steps102-110. The computer program is usually part of a computer-readable storage medium which comprises a suitable digital storage medium on which the computer program is stored.

FIG.6illustrates embodiments of a computer-readable storage medium99comprising instructions which, when executed by a computer or calculation unit60, cause the computer or calculation unit60to carry out the steps of the method100according to any one of aspects and/or embodiments discussed herein.

The computer-readable storage medium99may be provided for instance in the form of a data carrier carrying computer program code for performing at least some of the steps102-110according to some embodiments when being loaded into the one or more calculation units60. The data carrier may be, e.g. a ROM (read-only memory), a PROM (programable read-only memory), an EPROM (erasable PROM), a flash memory, an EEPROM (electrically erasable PROM), a hard disc, a CD ROM disc, a memory stick, an optical storage device, a magnetic storage device or any other appropriate medium such as a disk or tape that may hold machine readable data in a non-transitory manner. The computer-readable storage medium may furthermore be provided as computer program code on a server and may be downloaded to the calculation unit60remotely, e.g., over an Internet or an intranet connection, or via other wired or wireless communication systems.

The computer-readable storage medium99shown inFIG.6is a nonlimiting example in the form of a USB memory stick.

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 invention, as defined by the appended claims.