GB2540584A - Internal combustion engine comprising a fuel unit pump actuated by the crankshaft - Google Patents

Abstract

A reciprocating internal combustion engine has a crankshaft (145, Fig. 3), a fuel unit pump 180 having a movable plunger 181 for supplying fuel to at least one injector (160, Fig. 1). The crankshaft comprises at least one drive cam 10 for driving the movable plunger 181 of the fuel unit pump, and the at least one drive cam is arranged on at least one counterweight 145a of the crankshaft.

Description

INTERNAL COMBUSTION ENGINE COMPRISING A FUEL UNIT PUMP ACTUATED

BY THE CRANKSHAFT

TECHNICAL FIELD

The technical field relates to the fuel injection of an internal combustion engine, and in particular to the actuation of a fuel unit pump via the crankshaft of the internal combustion engine.

BACKGROUND

According to a possible configuration of the internal combustion engine injection system, a fuel unit pump is provided in order to supply fuel under pressure to the fuel injectors (injector nozzle).

This injection system is used for example in high-pressure injection system of diesel internal combustion engine.

The fuel unit pump is actuated by a drive cam mounted on a rotatable shaft of the internal combustion engine, preferably on the camshaft. More in detail, the fuel unit pump is provided with a movable plunger that is contacted by a drive cam, thus the rotary movement of the camshaft can be transmitted to the fuel unit pump, and in particular to the plunger of the fuel unit pump contacted by the drive cam, to actuate it.

More in detail, according to a known arrangement, the plunger is provided with a follower comprising a tappet roller that is contacted by the drive cam, so that the rotary movement of the camshaft can be transformed in a linear movement of the movable plunger of the fuel unit pump. The fuel unit pump is connected to the fuel injectors, preferably by means of a fuel rail, to supply fuel in the engine cylinder.

However, to transmit the rotary movement of the camshaft to the fuel unit pump and in particular to its movable plunger, there is the need to arrange the fuel unit pump in direct contact with the camshaft, preferably within the cylinder head of the internal combustion engine.

Additionally, current developments in the engine field aim at providing combustion improvements. For this purpose, the injection system will require the increase of the rail pressure from 200 MPa up to 250 MPa, and in some applications even above 300 MPa.

The increase in the rail pressure due to combustion improvements makes the installation of the fuel unit pump in contact with a drive cam of the camshaft critical due to higher pump absorbed torques and exchanged mechanical loads in the drive line.

Additionally, for the actuation of fuel unit pump with a drive cam arranged on the camshaft three or more cam lobes are needed to provide three or four pumping events, i.e. movement of the plunger in the pump ng position, during a combustion cycle of the engine. Due to the actuation by means of three or more cam lobes, the movement speed of the plunger is high, which inevitably leads to high values of the pump absorbed torque.

The actuation of the fuel unit pump with a rotatable shaft of the engine other than the camshaft has been proposed. For example, the actuation of the fuel unit pump with a drive cam mounted on the crankshaft of the internal combustion engine has been proposed. However, the need of mounting an additional component on the crankshaft inevitably leads to an undesired reduction of the available space, or to a repositioning of engine components.

Therefore, it is an object of an embodiment of the invention to provide an alternative actuation of the fuel unit pump while at the same time preventing the arrangement of additional components in the internal combustion engine.

Another object of the present invention is to allow a reduction of the mechanical stress exerted on both the fuel unit pump and on the rotatable shaft on which the drive cam for the pump actuation is arranged.

It is another object of the invention to increase the flexibility of the engine layout design, and in particular to increase the flexibility in the positioning of the fuel unit pump without providing an undesired increase in the engine dimensions and complexity. SUMMARY

These and other objects are achieved by the internal combustion engine according to an embodiment of the invention as defined in the independent claim. The dependent claims include preferred and/or advantageous aspects of said embodiment.

An embodiment of the invention provides an internal combustion engine comprising at least one cylinder having a piston movable within the cylinder and coupled to rotate a crankshaft, a fuel unit pump having a movable plunger for supplying fuel to at least one injector. The crankshaft comprises at least one drive cam for driving the movable plunger of the fuel unit pump, and the drive cam is arranged on at least one counterweight of the crankshaft.

An advantage of this solution is to provide an effective and simple actuation of the fuel unit pump while reducing mechanical stresses exerted during the actuation of the fuel unit pump. Therefore, the rail pressure can be increased in order to meet combustion improvements.

Additionally, the provision of a drive cam for the actuation of the fuel unit pump on a counterweight of the crankshaft do not need added parts (added components) and have minimal requirements for additional space within the engine.

According to an aspect of the invention, the at least one drive cam is an integral part of the counterweight of the crankshaft. Thanks to this aspect, the fuel unit pump packaging and integration within the internal combustion engine is simple and easy to obtain. In particular, no additional components are needed for the actuation of the fuel unit pump because of the integration of the drive cam in the counterweight of the crankshaft.

According to an aspect of the invention, the drive cam arranged on at least one counterweight of the crankshaft comprises at least two cam lobes.

Advantageously, the arrangement of the drive cam on the crankshaft and in particular on a counterweight thereof, allcws also to reduce the number of cam lobes needed for providing the movement of the plunger in the pumping position during the engine operation, and in particular during a combustion cycle of the engine.

Advantageously, the number of the cam lobe of the drive cam can be selected to provide the desired number of movements of the movable plunger in a pumping position, for each combustion cycle, preferably by also taking into account the number of complete rotation of the crankshaft in each combustion cycle.

According to different possible embodiments, two, three or four cam lobes of the drive cam can be provided. According to an aspect of the invention, for example in a four-cylinders engine, the drive cam comprises two cam lobes.

By providing two cam lobes on the crankshaft, it is possible to obtain two actuations, i.e. two movements in the pumping position of the movable plunger, during a complete rotation of the crankshaft. The same applies to a drive cam comprising a greater number of cam lobes, for example three or four.

Advantageously, the movement of the plunger in the pumping position can be carried out in an extended surface of the drive cam. Advantageously, the plunger speed during its actuation can be reduced and thus the fuel unit pump absorbed torque can be also reduced.

The arrangement of two cam lobes allows to decrease the local curvature radius of the drive cam profile intended to engage the movable plunger for the actuation of the fuel unit pump. Therefore, the local mechanical stresses, and in particular hertzian contact stress can be advantageously reduced.

According to an aspect of the invention, each of the two cam lobes extends along an arc of the drive cam defined by an angle of substantially 180 degrees. An advantage of this aspect is to provide a simple profile of the drive cam allowing at the same time an effective actuation of the movable plunger with a reduction of its velocity and thus of the pump absorbed torque. According to this aspect the profile of the drive cam provides a reduction of the curvature radius of the drive cam and thus of the hertzian stress. It has to be noted that if a number of cam lobes greater than two is provided, the arc of the drive cam along which each cam lobe extends is reduced, and preferably proportionally reduced, depending on the number of cam lobes. For example, if three cam lobes are provided, each of said three cam lobes extends along an arc of the drive cam defined by an angle of substantially 120 degrees.

According to an aspect of the invention, the drive cam arranged on at least one counterweight of the crankshaft is configured to provide a number of movements of movable plunger in a pumping position, for each combustion cycle, equal to the number of the cylinders of the of the internal combustion engine.

Thanks to this solution, the actuation of the fuel unit pump by the movement of the plunger can be easily carried out by the drive cam arranged on the counterweight of the crankshaft, by providing the necessary quantity of fuel needed.

According to an aspect of the invention, a combustion cycle is completed in four-strokes of the piston inside said cylinder, corresponding to two rotations of the crankshaft. An advantage of this embodiment is that the arrangement of the drive cam on the counterweight of the crankshaft allows to use two rotations of the crankshaft to provide the desired actuation of the fuel unit pump.

Thus the number of movements of the plunger in the pumping position can be generated during two rotations of the crankshaft, thus reducing the speed of the movable plunger and consequently of the pump absorbed torque.

According to still another embodiment of the invention, the drive cam arranged on at least one counterweight of the crankshaft is configured to provide a movement of the movable plunger in a pumping position, in a rotation of substantially 180 degrees of the crankshaft. Advantageously, the movement of the plunger of the fuel unit pump can be carried out in an extended surface of the drive cam, thus reducing the speed of the movable plunger, which leads to a reduction of the absorbed torque by the fuel unit pump.

According to still another aspect of the invention, the internal combustion engine further comprises a lubrication channel to supply a lubrication fluid to the movable plunger of the fuel unit pump. Thanks to this solution the mechanical stress and also the generated heat can be easily controlled.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features, advantages and details appear, by way of example only, in the following detailed description of embodiments, with reference to the accompanying drawings, in which: • Figure 1 shows a possible embodiment of an automotive system comprising an internal combustion engine; • Figure 2 is a cross-section according to the plane A-A of an internal combustion engine belonging to the automotive system of Figure 1; • Figure 3 is a schematic view of a crankshaft of a possible embodiment of the internal combustion engine according to the invention, wherein the fuel unit pump is not shown; • Figure 4 is a schematic view of a possible embodiment of the internal combustion engine according to the invention, wherein a fuel unit pump actuated by the crankshaft is shown; • Figure 4a is a section view a fuel unit pump actuated by the crankshaft according to figure 4.

DETAILED DESCRIPTION

Exemplary embodiments will now be described with reference to the enclosed drawings without intent to limit application and uses.

Some embodiments may include an automotive system 100, as shown in Figures 1 and 2, that includes an internal combustion engine (ICE) 110 having an engine block 120 defining at least one cylinder 125 having a piston 140 coupled to rotate a crankshaft 145. A cylinder head 130 cooperates with the piston 140 to define a combustion chamber 150. A fuel and air mixture (not shown) is disposed in the combustion chamber 150 and ignited, resulting in hot expanding exhaust gasses causing reciprocal movement of the piston 140. The fuel is provided by at least one fuel injector 160 and the air through at least one intake port 210. The fuel is provided at high pressure to the fuel injector 160 from a fuel rail 170 in fluid communication with a high pressure fuel pump 180 that increase the pressure of the fuel received from a fuel source 190. Each of the cylinders 125 has at least two cylinder valves 215, actuated by the camshaft 135 rotating in time with the crankshaft 145. The cylinder valves 215 selectively allow air into the combustion chamber 150 from the port 210 and alternately allow exhaust gases to exit through a port 220. In some examples, a cam phaser 155 may selectively vary the timing between the camshaft 135 and the crankshaft 145.

The air may be distributed to the air intake port(s) 210 through an intake manifold 200. An air intake duct 205 may provide air from the ambient environment to the intake manifold 200. In other embodiments, a throttle body 330 may be provided to regulate the flow of air into the manifold 200. In still other embodiments, a forced air system such as a turbocharger 230, having a compressor 240 rotationally coupled to a turbine 250, may be provided. Rotation of the compressor 240 increases the pressure and temperature of the air in the duct 205 and manifold 200. An intercooler 260 disposed in the duct 205 may reduce the temperature of the air. The turbine 250 rotates by receiving exhaust gases from an exhaust manifold 225 that directs exhaust gases from the exhaust ports 220 and through a series of vanes prior to expansion through the turbine 250. The exhaust gases exit the turbine 250 and are directed into an exhaust system 270. This example shows a variable geometry turbine (VGT) with a VGT actuator 290 arranged to move the vanes to alter the flow of the exhaust gases through the turbine 250. In other embodiments, the turbocharger 230 may be fixed geometry and/or include a waste gate.

The exhaust system 270 may include an exhaust pipe 275 having one or more exhaust aftertreatment devices 280. The aftertreatment devices may be any device configured to change the composition of the exhaust gases. Some examples of aftertreatment devices 280 include, but are not limited to, catalytic converters (two and three way), oxidation catalysts, lean NOx traps, hydrocarbon adsorbers, selective catalytic reduction (SCR) systems, and particulate filters. Other embodiments may include an exhaust gas recirculation (EGR) system 300 coupled between the exhaust manifold 225 and the intake manifold 200. The EGR system 300 may include an EGR cooler 310 to reduce the temperature of the exhaust gases in the EGR system 300. An EGR valve 320 regulates a flow of exhaust gases in the EGR system 300.

The automotive system 100 may further include an electronic control unit (ECU) 450 in communication with one or more sensors and/or devices associated with the ICE 110. The ECU 450 may receive input signals from various sensors configured to generate the signals in proportion to various physical parameters associated with the ICE 110. The sensors include, but are not limited to, a mass airflow and temperature sensor 340, a manifold pressure and temperature sensor 350, a combustion pressure sensor 360, coolant and oil temperature and level sensors 380, a fuel rail pressure sensor 400, a cam position sensor 410, a crank position sensor 420, exhaust pressure and temperature sensors 430, an EGR temperature sensor 440, and an accelerator pedal position sensor 445. Furthermore, the ECU 450 may generate output signals to various control devices that are arranged to control the operation of the ICE 110, including, but not limited to, fuel injectors 160, the throttle body 330, the EGR Valve 320, the VGT actuator 290, and the cam phaser 155. Note, dashed lines are used to indicate communication between the ECU 450 and the various sensors and devices, but some are omitted for clarity.

Turning now to the ECU 450, this apparatus may include a digital central processing unit (CPU) in communication with a memory system, or data carrier, and an interface bus. The CPU is configured to execute instructions stored as a program in the memory system, and send and receive signals to/from the interface bus. The memory system may include various storage types including optical storage, magnetic storage, solid state storage, and other non-volatile memory. The interface bus may be configured to send, receive, and modulate analog and/or digital signals to/from the various sensors and control devices.

The program stored in the memory system is transmitted from outside via a cable or in a wireless fashion. Outside the automotive system 100 it is normally visible as a computer program product, which is also called computer readable medium or machine readable medium in the art, and which should be understood to be a computer program code residing on a carrier, said carrier being transitory or non-transitory in nature with the consequence that the computer program product can be regarded to be transitory or non-transitory in nature.

An example of a transitory computer program product is a signal, e.g. an electromagnetic signal such as an optical signal, which is a transitory carrier for the computer program code. Carrying such computer program code can be achieved by modulating the signal by a conventional modulation technique such as QPSK for digital data, such that binary data representing said computer program code is impressed on the transitory electromagnetic signal. Such signals are e.g. made use of when transmitting computer program code in a wireless fashion via a Wi-Fi connection to a laptop.

In case of a non-transitory computer program product the computer program code is embodied in a tangible storage medium. The storage medium is then the non-transitory carrier mentioned above, such that the computer program code is permanently or non-permanently stored in a retrievable way in or on this storage medium. The storage medium can be of conventional type known in computer technology such as a flash memory, an Asic, a CD or the like.

Instead of an ECU 450, the automotive system 100 may have a different type of processor to provide the electronic logic, e.g. an embedded controller, an onboard computer, or any processing module that might be deployed in the vehicle.

Returning on the fuel injection, according to a possible embodiment, the internal combustion engine 110 is provided with a fuel unit pump 180 connected to a fuel source 190, from which the fuel is provided. The fuel unit pump 180 is connected to one or more fuel injectors 160 (injector nozzle), preferably by a fuel rail 170.

As it will disclosed more in detail later, the fuel unit pump 180 is actuated by the rotation of the crankshaft 145 of the internal combustion engine 110. In fact, as already mentioned above, the internal combustion engine 110 comprises at least one cylinder 125 having a piston 140 coupled to rotate a crankshaft 145. The piston reciprocates inside the cylinder 125 due to the combustion of fuel supplied inside the cylinder.

It has to be noted that according to the number of strokes of the piston 140 inside the cylinder 125, the engine can be a two-strokes engine, wherein the combustion cycle is completed every rotation of the crankshaft 145, or a four-strokes engine wherein a combustion cycle is completed every two rotations of the crankshaft 140. According to an embodiment of the invention, the internal combustion engine 110 is a four-strokes engine and combustion cycle is completed in four-strokes of the piston 140 inside said cylinder 125, corresponding to two rotations of the crankshaft 145 (720 degrees of rotation of the crankshaft 145).

As for example shown in figure 3, the crankshaft 145 is connected to each piston 140, movable inside the cylinder 125 by means of a crank assembly comprising a connecting rod 140a and a crank pin 140b. The connecting rod 140a is rotatably constrained at one end to the piston 140 and to another end to a crank pin 140b.

The axis of the crank pin 140b is arranged at a distance from the rotation axis X of the crankshaft 145 so that the crank pin 140b converts the movement of the piston 140 inside the cylinder in the rotary movement of the crankshaft about the crankshaft rotation axis X.

According to a possible embodiment for each cylinder 125, and thus for each piston 140, a connecting rod 140a and a correspondent crank pin 140b is provided.

It has to be noted that the crank arms 140c can be provided for supporting the crank pin 140b at distance from the crankshaft rotation axis X.

To provide the desired engine balance, at least one counterweight 145a (also known as countermass) is provided, preferably for each piston 140. The counterweight is preferably a part (component) integrated with the crankshaft 145, but according to possible embodiments, it can be provided as separate component constrained to the crankshaft.

The counterweight is preferably arranged in correspondence of the crank arm 140c supporting the crank pin 140b. Preferably, the counterweight is arranged on the opposite side of the crank pin 140b with respect to the crankshaft rotation axis X. According to a preferred embodiment, as for example shown in figure 3, the counterweight 145a and the crank arm 140c forms a single element.

According to an embodiment of the invention the crankshaft comprises at least one drive cam 10 for driving the movable plunger 181 of the fuel unit pump 180 and said drive cam is arranged on at least one counterweight 145a of the crankshaft 145. The drive cam 10 is arranged in engagement (i.e. to contact) the movable plunger 181 of the fuel unit pump 180, to activate it.

According to a preferred embodiment (as for example shown in figures 3,4 and 4a), the drive cam 10 is an integral part of the counterweight 145a, i.e. the drive cam 10 is integrated in the counterweight 145a of the crankshaft. In other words, according to a possible embodiment, the counterweight 145a is shaped so as to form a drive cam 10.

More in detail, as for example shown in figures 4 and 4a, according to a possible embodiment, the fuel unit pump 180 comprises a movable plunger 180a that is moved, inside the body of the fuel unit pump 180, for drawing fuel from the fuel source and for pressurizing it before the delivery to the fuel injector 160.

For this purpose the fuel unit pump 180 is provided with a fuel inlet opening and a fuel outlet opening provided on the body of the fuel unit pump, and fluidically connected to the chamber provided therein, inside which the plunger 181 is moveable.

The movable plunger 181 is preferably movable along a longitudinal movement direction. More in detail, the plunger 181 is movable with respect to fuel unit pump body, preferably inside a chamber (not shown) provided inside the fuel unit pump body.

The longitudinal movement direction of the movable plunger 181 preferably corresponds to the longitudinal axis of the plunger 181.

More in detail, the fuel is supplied to the fuel injector 160 from the fuel unit pump 180 due to a pumping movement of the movable plunger 181. In fact, the plunger 181 is movable between a non-pumping position, in which it is preferably extracted from the body of the fuel unit pump, and in particular from a chamber provided therein, and a pumping position in which it is preferably moved inside the fuel unit pump body.

Returning means 180a, for example comprising at least one spring or other elastic means, can be provided to maintain the movable plunger 181 in the non-pumping position.

The movable plunger 181 of the fuel unit pump 180, is actuated along the movement direction to reach the pumping position, by means of the crankshaft 145, and in particular by at least one drive cam 10 of the counterweight 145a of the crankshaft.

It has to be noted that according to a possible embodiment, as for example shown in figures 4 and 4a, the movable plunger 181 is provided with a follower comprising a tappet roller 182 intended to contact the drive cam 10. The tappet roller 182 rotatably engages the crankshaft 145, and in particular the drive cam 10 arranged on the counterweight 145a.

This solution allows to reduce friction between the plunger 181 and the crankshaft 145. In other embodiments, not shown, the movable plunger 181 is provided with a portion intended to contact the drive cam 10 which is not rotatable.

The drive cam 10 arranged on the counterweight 145a of the crankshaft 145 comprises at least two cam lobes 11. The cam lobe 11 is protruding from a base cam surface 12 (known also as “cam base circle”). In fact, as for example shown in figure 4a, the cam lobe 11 is defined as a portion protruding from a circular line 12, i.e. the base circle, of the drive cam 10.

The cam lobe 11 is provided to move the plunger 181 in the pumping position. It has to be noted that, according to possible embodiments, the shape of the drive cam 10 and in particular the number of the cam lobes 11 can be selected for example to actuate the fuel unit pump by providing the desired number of activations (i.e. movements of the plunger 181 in the pumping position) during a complete rotation of the crankshaft 145.

As already mentioned above, the number of the cam lobes 11 of the drive cam 10 can be selected to provide the desired number of movements of the movable plunger in a pumping position. According to different possible embodiments, two, three or four cam lobes of the drive cam can be provided. In the embodiment shown in the figures, two cam lobes 11 are provided on the drive cam 10.

According to a possible embodiment, the drive cam 10 mounted on the counterweight 145a of the crankshaft is configured to provide a number of movements of the movable plunger 181 in the pumping position, for each combustion cycle, that is equal to the number of the cylinders 125 of the of the internal combustion engine.

More in detail, the drive cam 10 can be selected to provide a number of movements of the plunger 181 in the pumping position, also called pumping events, that is equal to the number of the cylinders 125 of the engine 110.

For example, in an internal combustion engine 110 having four cylinders 125 (see for example figure 2) the drive cam 10 can be shaped, preferably by selecting a desired number of cam lobes 11, to provide four pumping events for each combustion cycle of the engine.

As mentioned above in a two-strokes engine, the combustion cycle is completed every rotation of the crankshaft 145, and in a four-strokes engine the combustion cycle is completed every two rotations of the crankshaft 140.

Therefore, the shape of the drive cam 10, and in particular the number of cam lobes 11 can be selected to take into account the number of rotation(s) of the crankshaft 145 needed to provide a complete combustion cycle.

According to an embodiment of the invention, the internal combustion engine 110 is a four-strokes engine and a combustion cycle is completed in four-strokes of the piston 140 inside the cylinder 125, corresponding to two rotations of the crankshaft 145 (720 degrees of rotation of the crankshaft 145). Therefore, two pumping events have to be provided for a rotation of the crankshaft 145.

According to an aspect of the invention, the number of cam lobes 11 of the drive cam 10 is proportional to the number of the engine cylinders, and preferably is equal to the number of the engine cylinder divided by two, for example when the engine 110 is a four-strokes engine and a combustion cycle is completed in two rotations of the crankshaft 145 (720 degrees of rotation of the crankshaft 145).

For example, in the embodiment shown in the figures, the engine 110 comprises four cylinders 125 and the drive cam 10 comprises two cam lobes 11. However, different possible embodiments can be provided, for example a six-cylinders engine can be provided with a drive cam 10 comprising three cam lobes 11, and an eight-cylinders engine can be provided with a drive cam 10 comprising four cam lobes 11.

According to an embodiment of the invention, the drive cam 10 mounted on at least one counterweight 145a of the crankshaft is configured to provide a movement of the movable plunger 181 in a pumping position, i.e. to provide a pumping event, during a rotation of 180 degrees of the crankshaft.

As for example shown in figure 4, the drive cam 10 arranged on the counterweight 145a of the crankshaft comprises two cam lobes 11.

By doing so, the fuel unit pump 180 is actuated, due to the movement of the movable plunger 181 in the pumping position, two times during a complete rotation of the crankshaft 145 about the rotation axis X.

Each of the two cam lobes 11, preferably protruding from the base circle 12 of the drive cam 10, extends along an arc of the drive cam 10 defined by an angle of substantially 180 degrees. In fact, as for example shown in figure 4, the cam lobe 11 extends substantially for half of the length of the profile of the drive cam 10.

When two cam lobes 11 are provided, the drive cam has substantially an oval shape (see for example figures 4 and 4a) with the two cam lobes 11 extending along two arcs of the drive cam each defined by an angle of substantially 180 degrees.

According to an embodiment, the internal combustion engine comprises a lubrication channel to supply a lubrication fluid to the movable plunger 181 of the fuel unit pump 180. More in detail, the lubrication channel is intended to lubricate the contact surface of the movable plunger 181 with the drive cam 10.

The lubrication channel, not shown in the figures, is fluidly connected to a source of lubricant fluid, such as for example oil, in a known manner. In particular, it is known that the internal combustion engine 110 is provided with a lubricating circuit, to which the lubricating channel is connected.

While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.

REFERENCE NUMBERS 10 drive cam 11 cam lobe 12 cam base circle X rotation axis of the crankshaft 100 automotive system 110 internal combustion engine (ICE) 120 engine block 125 cylinder 130 cylinder head 135 camshaft 140 piston 140a connecting rod 140b crank pin 140c crank arm 145 crankshaft 145a counterweight of the crankshaft 150 combustion chamber 155 cam phaser 160 fuel injector 170 fuel rail 180 fuel pump 180a returning means 181 movable plunger 182 tappet roller 190 fuel source 200 intake manifold 205 air intake duct 210 intake air port 215 valves of the cylinder 220 exhaust gas port 225 exhaust manifold 230 turbocharger 240 compressor 250 turbine 260 intercooler 270 exhaust system 275 exhaust pipe 280 exhaust aftertreatment device 290 VGT actuator 300 EGR system 310 EGR cooler 320 EGR valve 330 throttle body 340 mass airflow and temperature sensor 350 manifold pressure and temperature sensor 360 combustion pressure sensor 380 coolant and oil temperature and level sensors 400 fuel rail pressure sensor 410 cam position sensor 420 crank position sensor 430 exhaust pressure and temperature sensor 440 EGR temperature sensor 445 accelerator pedal position sensor 450 electronic control unit (ECU)

Claims (8)

1. Internal combustion engine (110) comprising at least one cylinder (125) having a piston (140) coupled to rotate a crankshaft (145), a fuel unit pump (180) having a movable plunger (181) for supplying fuel to at least one injector (160), wherein the crankshaft comprises at least one drive cam (10) for driving the movable plunger of the fuel unit pump, the at least one drive cam being arranged on at least one counterweight (145a) of the crankshaft.

2. The internal combustion engine according to claim 1, wherein said at least one drive cam (10) is an integral part of the counterweight (145a) of the crankshaft.

3. The internal combustion engine according to any previous claim, wherein said drive cam (10) arranged on at least one counterweight (145a) of the crankshaft comprises at least two cam lobes (11).

4. The internal combustion engine according to claim 3, wherein said drive cam (10) arranged on at least one counterweigh! (145a) of the crankshaft comprises two cam lobes, wherein each of said two cam lobes (11) extends along an arc of the drive cam (10) defined by an angle of substantially 180 degrees.

5. The internal combustion engine according to any previous claim, wherein said drive cam (10) arranged on at least one counterweight (145a) of the crankshaft is configured to provide a number of movements of the movable plunger (181) in a pumping position, for each combustion cycle, equal to the number of the cylinders (125) of the of the internal combustion engine.

6. The internal combustion engine according to any previous claim, wherein a combustion cycle is completed in four-strokes of the piston (140) inside said cylinder (125) corresponding to two complete rotations of the crankshaft (145).

7. The internal combustion engine according to any previous claim, wherein said drive cam (10) arranged on at least one counterweight (145a) of the crankshaft is configured to provide a movement of the movable plunger (181) in a pumping position in a rotation of substantially 180 degrees of the crankshaft.

8. The internal combustion engine according to any previous claim, comprising a lubrication channel to supply a lubrication fluid to the movable plunger (181) of the fuel unit pump (180).