VALVE TRAIN ASSEMBLY
A cam phasing mechanism (1) for a cam assembly (100) of an internal combustion engine, the cam assembly (100) comprising a camshaft (120) and an actuator (130) for opening a valve (505) at a reference position of rotation of the camshaft (120), the cam phasing mechanism (1) comprising: a force transfer member (2a) for interposition between the camshaft (120) and the actuator (130) of the cam assembly (100) for transferring force between the camshaft (120) and the actuator (130); and an adjuster (2b) for selectively moving the force transfer member (2a) to adjust the reference position of rotation of the camshaft (120).
The present invention relates to valve train assemblies of internal combustion engines, specifically to variable valve train components of a valve train assembly.
BACKGROUNDInternal combustion engines, such as four-stroke diesel engines, may comprise variable valve train components. Valve train assemblies may include a camshaft that rotates with engine speed to sequentially move a push rod, rocker arm and valve. An eccentric cam lobe determines the movement of the push rod for each revolution of the camshaft. For example, valve train assemblies may comprise a variable valve lift to provide for control of an opening of a valve (for example, control of an opening of an intake valve and/or exhaust valve) by alternating between at least two or more modes of operation (e.g. valve-lift modes). The timing and/or duration of the valve lift may be controlled by the valve train assembly. Optimising valve operations helps to reduce fuel consumption, particularly when the engine speed and/or engine load is varied.
SUMMARYAspects of the present invention are listed in the accompanying claims.
Features of the present invention will now be described, by way of example only, with reference to the accompanying drawings, of which:
Throughout, like reference signs denote like features.
DESCRIPTIONReferring to
The cam assembly 100 shown in
In the example shown, the first member 4 is continuously moveable relative to the second member 5 for continuously adjusting the reference position of rotation of the camshaft 120 within a predetermined range. The predetermined range may be 50 degrees of rotation of the camshaft, corresponding to 100 crank angle degrees (100 CAD). That is, the reference position of rotation of the camshaft 120 at which the valve 505 is caused to open or close can be shifted, i.e. phased, by 50 angular degrees of rotation of the camshaft 120.
In the example provided, the first member 4 of the adjuster 2b is a threaded bushing and the second member 5 is a wheel gear. That is, the first member 4 and second member 5 are engageable by respective threaded portions. The respective threaded portions mesh together to provide the required movement of the first member 4 relative to the second member 5 to allow a translational position of the force transfer member 2a to be changed. As the second member 5 is rotated about an axis, the first member 4 is moved along the second member 5 to a translated location of the first member 4′. This movement is shown as translational motion of the first member 4 about a translation axis L in a first direction B. The axis of rotation of the second member 5 may be coexist on translation axis L. The first member 4 is configured to move up and down the translation axis L. Movement of the first member 4 in the first direction B may, for example, cause advance timing of the valve 505. That is, the valve 505 may open sooner in an engine cycle.
As shown in
As discussed, the pivotable motion of the lever arm 31 is achieved by the bearing 6. The bearing 6 comprises a portion that is coupled to the first member 4. The bearing 6 is therefore configured to experience the same translational motion of the first member 4 with respect to the second member 5, which is represented by a translated location of the bearing 6′ in
The cam phasing mechanism 1 of
In the example shown in
The cam phasing mechanism 1 of
Turning to
The camshaft 120 shown in
As is best shown in
An enlarged view of a roller assembly region A of the force transfer member 2a is shown in
The cam phasing mechanism 1 is configured to change the timing at which a valve, such as the exhaust valve opens. In the example, shown, a valve phasing range F represents the degree to which the reference timing of the exhaust valve 1120 can be changed to advance or retard the opening timing of the exhaust valve. For example, the early phasing 1101 of the valve opening, e.g. early exhaust valve opening (EEVO) may be up to 100 crank angle degrees, corresponding to 50 camshaft angle degrees from the reference timing of the exhaust valve 1120. Movement of the timing of the exhaust valve opening towards the reference timing of the exhaust valve 1120 may be considered to be late phasing 1102 in this example. The EEVO scenarios moves the timing of the maximum lift of the exhaust valve towards bottom dead centre (BDC) timing of a piston of the internal combustion engine.
As shown in
In the example shown in
In
The first actuator 710 comprises a slave part 710a and a master part 710b that are separable from each other. Each of the slave part 710a and the master part 710b is shown as a rod that are moveable with respect to each other. The slave part 710a is a first rod that is moveable within a hole provided in the second actuator 720. The master part 710b is a second rod that is moveable within a hole provided in a housing 770 of the actuation mechanism 700. In the orientation shown in
The actuation mechanism 700 comprises a controller that allows a working fluid to enter the housing 770 via a fluid inlet 730. The controller in this example is a spool valve 750. The spool valve 750 comprises a rotating member 751 such as a cam and a sliding member 752 which acts as a valve. As the rotating member 751 rotates about a motion axis M2 in direction R3, a raised profile of the rotating member 751 causes the sliding member 752 to move and allow the working fluid to communicate between the fluid inlet 730 and an intermediate passageway 731. The intermediate passageway 731 contains a non-return valve 760. The non-return valve 760 comprises a moveable part 761 such as a ball and a resilient member such as a spring S. The moveable part 761 is moveable relative to a base 762 to open the non-return valve 760 by moving the moveable part 761 along a motion axis M3 and allow the working fluid to flow to a working zone 733. The working zone 733 is a reservoir for causing hydraulic lock of the second actuator 720 and varies in volume. The working zone 733 comprises a reserve passageway 734 which allows a volume of working fluid to remain in the working zone 733 when the second actuator 720 is moved fully down by the exhaust rocker arm assembly 320 when the exhaust valve 525 is closed. Finally, working fluid is removed from the working zone 733 through a fluid outlet 735.
In order to position the second actuator 720 in the correct location in the housing 770 when in the first position 700-1, the working fluid forces the second actuator 720 to an extent of the housing 770, which may correspond to an upward direction. The second actuator 720 therefore comprises an abutment which engages with a corresponding abutment of the housing 770 as shown in abutment area N. The second actuator 720 is held in abutment with the housing 770 by a pressure of the working fluid as well as the action of the non-return valve 760 which prevents working fluid from escaping the working zone 733.
Each rocker arm assembly 310, 320 is biased to close the valve as a default configuration. Therefore, the exhaust rocker arm assembly 320 exerts a force against the first actuator 710. As the exhaust camshaft 121 is rotated, the socket 323 is brought towards the second actuator 720. During this event, the exhaust valve 525 continues to close, as shown by the downward arrow in
As discussed above, the movement of the first actuator 710 is governed by a first driver and the movement of the second actuator 720 is governed by a second driver that is different to the first driver. In the example provided, the first driver comprises a mechanical force and the second driver comprises a hydraulic force.
In
The period between the second position 700-2 and the third position 700-3 may be changed by changing the timing of opening the exhaust valve 525. That is, the motion of the second actuator 720 towards the lower part of the housing 770 is independent of rotation of the exhaust camshaft 121. In this instance, the period at which the exhaust valve 525 is constantly kept open is variable. Specifically, the motion of the second actuator 720 is independent of rotation of the exhaust camshaft 121 when the raised profile 123b of the exhaust camshaft 121 no longer raises the exhaust valve 525. That is the exhaust valve closing (EVC) event is always substantially at the same point and is independent of the timing of the exhaust valve opening (EVO). Selecting the timing of the opening of the exhaust valve 525 to begin earlier than that of a standard exhaust valve lift event (e.g. that shown un the reference timing diagram of
In some instances, for example in the example provided, the first force transmitter 610 controls the opening of the fluid outlet 735 and acts as a controller. The first force transmitter 610 may comprise a channel which allows the fluid outlet 735 to communicate with the return line 606 of the hydraulic circuit. This may occur when the intake valve 515 is lifted to around 0.5 to 0.7 mm of lift since the first force transmitter 610 governs the lifting operation of the valve to raise the intake valve 515 from the intake valve seat (not shown). In this instance, the timing location of the third position 700-3 is determined by the intake valve operation. The exhaust valve 525 operation and the intake valve operation 515 are therefore directly linked by the actuation assembly 600.
The operation of the actuation mechanism 700 sequentially between the first to fourth positions 700-1 to 700-4 elongates the period during which the exhaust valve is open compared to the period shown in the reference timing diagram of
The first part 810 and the second part 820 are separable from each other. Each of the first part 810 and the second part 820 are shown as a cylinder that each have a cavity 811, 821 for being filled by the working fluid. Together the cavities 811, 821 form a reservoir. As the first part 810 and the second part 820 move with respect to each other, the size of the reservoir changes even though the size of the cavities 811, 821 remain fixed. In the orientation shown in
The motion controller 800 comprises a controller that allows a working fluid to enter the housing 870 via a fluid inlet 831. The controller in this example is a non-return valve 860. The non-return valve 860 comprises a moveable part 861 such as a ball, a resilient member such as a spring S and a switch 862 for opening and closing the non-return valve 860. The moveable part 861 is moveable relative to the switch 862 to open the non-return valve 860 by moving the moveable part 861 along a motion axis M3 and allow the working fluid to flow to a working zone 833. The working zone 833 is the reservoir for causing hydraulic lock of the first part 810 and second part 820 and varies in volume. The working zone 833 comprises a port 832 which allows a volume of working fluid to fill or be released in the working zone 833 when the second part 820 is moved away from the first part 810 to allow the fluid inlet 831 to communicate with the cavities 811, 821 of the respective first part 811 and second part 821. The working fluid can be removed from the working zone 833 through the fluid inlet 831 when the motion controller 800 is move to a locked state and the switch 862 is open in the position shown in
Also shown in
A further fluid inlet 830 is shown that is communicable with a further fluid outlet 835a when a pressure release portion 802 is aligned with the inlet 830 and outlet 835a. The pressure release portion 802 is used to relieve pressure from the working zone 733 of the actuation mechanism 700 as previously described.
The camshaft arrangement shown in
The first state is an unlocked state 800-1 of the motion controller 800. In the unlocked state 800-1, the first part 810 and second part 820 of the motion controller 800 are separated by the port 832. The port 832 is closed when the first part 810 and second part 820 are brought together as shown in the locked state 800-2. When in the unlocked state 800-1, the second part 820 is moveable towards the first part 810 in valve opening direction J by the raised profile of the cam lobe of the camshaft 111 without imparting a lifting force to the intake valve 515. A resistance to relative movement between the first part 810 and the second part 820 in the unlocked state 800-1 is provided by a resilient member such as the spring S.
In the unlocked state 800-1, shown in
A first arrangement 800a of the motion controller 800 is shown in
Rotation of the intake camshaft 111, causes the force transmitter 601 to move relative to the housing 870 of the motion controller 800 in valve opening direction J. That is, the first part 810 and the second part 820 move in combination (i.e. in tandem) to open the intake valve 515 and raise the intake valve 515 away from the intake valve seat. In this example, the direction of movement of the first part 810 and second part 820 is an upward direction.
As the combined first part 810 and the second part 820 move in a direction to open the valve (i.e. the valve opening direction J), the port 832 becomes aligned with the fluid inlet 835b. Given that the spool valve 850 is in an open position by turning the rotating member 851, working fluid can be transferred through an aperture in the sliding member 852 and out through the fluid outlet 835c and return line 607. As the working fluid leaves the reservoir the first part 810 and second part 820 move towards each other and directly engage by mechanical contact. The second arrangement 800b shows the situation as the port 832 becomes aligned with the fluid inlet 835b and just before the first part 810 and second part 820 move towards each other. The third arrangement 800c shows the situation as enough working fluid has left the reservoir for the first part 810 and second part 820 to directly engage by mechanical contact.
The corresponding location of the second arrangement 800b and the third arrangement 800b is shown on the valve timing diagrams of
As the intake camshaft 111 continues to rotate, an interface between the first part 810 and second part 820 which is where the port 832 formally existed, is moved towards the fluid inlet 831, as shown in the fifth arrangement 800e of
It will be appreciated that when the intake camshaft 111 comprises the two raised profiles 113b, 113c, as shown in
Although the intake camshaft 111 may comprise the two raised profiles 113b, 113c, as shown in
As shown in
Systems such as the one illustrated in
The specific system shown in
As shown in
Referring now to
As shown in
The engine brake rocker arm assembly 1530 comprises at the second end 1530b an engine brake control capsule 2008 (which is illustrated in isolation in
The engine brake rocker arm assembly 1530 is configured in the engine brake ON configuration when the engine is operating in engine brake mode. When the engine is operating in engine brake mode, as a camshaft rotates, for example the camshaft 1350 illustrated in
The engine brake rocker arm assembly 1530 is configured in the engine brake OFF configuration when the engine is operating in normal drive mode. In the engine brake OFF configuration, the movement of the push rod 2002 caused by the cam profile of the engine brake cam 1320 is absorbed as a lost motion stroke by the engine brake control capsule 2008 so that the engine brake rocker arm assembly 1530 does not transfer any movement to the exhaust valve 2006.
As is known in the art, the engine brake control capsule 2008 may be of the type that comprises a first body 2008a and a second body 2008b each comprising a circular end portion that is crenulated around its length and which end portions face each other. One of the bodies 2008a, 2008b is rotatable about it longitudinal axis relative to the other of the bodies 2008a, 2008b between a first position and a second position to configure the engine brake control capsule 2008 in the engine brake OFF configuration or the engine brake ON configuration.
When the engine brake control capsule 2008 is in the engine brake ON configuration the raised portions of each of the crenulated circular end portions face each other such that the first body 2008a and the second body 2008b act as a single unit and transfer the movement of the engine brake rocker arm assembly 1530 to the exhaust valve 2006 by means of a member 2009. When the engine brake control capsule 2008 is in the engine brake OFF configuration the crenulated circular end portions are positioned so that every raised portion faces a recessed portion so that the first body 2008a is moveable relative to the second body 2008b to absorb the movement of the engine brake rocker arm assembly 1530 as a lost motion stroke so that no movement is transferred to the exhaust valve 2006 via the member 2009. The engine brake control capsule 2008 comprises a lost motion spring 2010 for biasing the first body 2008a and the second body 2008b away from each other.
The engine brake rocker arm assembly 1530 further comprises an actuator 2012 (shown separately in
An engine brake actuation cam 2022 is provided on a control camshaft 2024 which is rotatable 180 degrees between a first position and a second position to act on a second end 2016b of the first piston piece 2016 to drive the two-piece piston arrangement 2014 linearly to cause rotation of one of the first 2008a and second 2008b bodies, for example, the first body 2008a, relative to the other of the first 2008a and second 2008b bodies, for example, the second body 2008b, to configure the engine brake control capsule 2008 between the engine brake ON and OFF configurations. That is to say, when the actuation cam 2022 is rotated in a first sense, the two-piece piston arrangement 2014 is driven linearly in a first direction to cause rotation of one of the first 2008a and second 2008b bodies relative to the other of the bodies in a first sense to configure the brake control capsule 2008 in one of the ON and OFF configurations. And then, when the actuation cam 2022 is rotated back in the opposite sense, the two-piece piston arrangement 2014 is driven linearly back in the opposite direction to cause rotation of one of the first 2008a and second 2008b bodies relative to the other of the bodies in the opposite sense to configure the brake control capsule 2008 back into the other of the ON and OFF configurations. In the example shown in
The control camshaft 2024 may be operated in any suitable way, for example, by pressurised oil, pneumatically, or electromechanically.
The two-piece piston arrangement 2014 is provided with a threaded region 2026 arranged circumferentially around a section of its outer surface and which cooperates with a threaded region of one of the first 2008a and second 2008b bodies, in this example the first body 2008a, to rotate that body between the engine brake ON and OFF configurations when the two-piece piston arrangement 2014 is driven linearly. The two-piece piston arrangement 2014 is provided with a return spring 2020 for biasing the two-piece piston arrangement 2014 to a return position (in this example engine brake OFF position) and also a compliance spring 2028 arranged between the first piston piece 2016 and the second piston piece 2018. The compliance spring 2028 is much stiffer than is the return spring 2020 and is arranged to bias the actuator 2012 to configure the engine brake control capsule 2008 in the engine brake ON configuration. In some scenarios, the control cam 2022 will rotate but the rotatable one of the first 2008a and second bodies is not in a condition to rotate. This causes the compliance spring 2028 to be compressed by the first piston piece 2016 and once the rotatable one of the first 2008a and second bodies is in a condition to rotate, the compliance spring 2028 will extend and the actuator 2012 will configure the engine brake control capsule 2008 in the engine brake ON configuration.
The engine brake control capsule 2008 may also function as a mechanical lash adjuster.
Although for clarity it is not shown in
Suitable means is provided for activating and deactivating the exhaust rocker arm. For example, the exhaust rocker arm 300 may be provided with a similar control capsule and actuator to that illustrated in
Preferably, a control cam (not shown) for controlling the control capsule in the exhaust rocker arm is mounted on a common shaft 2024 as the control cam 2022 for controlling the engine brake control capsule 2008. In this way the common shaft 2024 can be used to control the engine brake control capsule 2008 to configure it into the engine brake ON configuration and to control the exhaust rocker arm control capsule to configure it into the exhaust rocker arm de-active configuration and can be used to control the engine brake control capsule 2008 to configure it into the engine brake OFF configuration and to control the exhaust rocker arm control capsule to configure it into the exhaust rocker arm active configuration.
When the engine is in normal drive mode there will be periods when the exhaust rocker arm has moved the exhaust valve bridge 400 out of contact with the exhaust brake rocker arm assembly 1530. A suitable arrangement is provided in order to maintain the connection between the exhaust brake rocker arm 1530 and the exhaust brake cam (e.g. via push rod 2002 in the example of
Referring now to
At a first end, the rocker arm arrangement 2500 comprises a first member 2502 for engagement with a push rod (not shown) that is in contact with a rotating exhaust cam (not shown). The first member 2502 may also function as a mechanical lash adjuster. At a second end, the rocker arm arrangement 2500 comprises an exhaust brake control capsule 2504 and associated actuator (not shown) that are similar to those described above with reference to
In operation, the rocker arm arrangement 2500 pivots in accordance with the cam profile (not shown) of the cam (not shown) that acts on the push rod (not shown) that acts in turn on the first member 2502. In normal engine drive mode, the exhaust brake control capsule 2504 is in the engine brake OFF configuration and provides no effect. In normal engine drive mode, the rocker arm arrangement 2500 pivots through a lost motion stroke X before contacting the second member 2506 to cause the second member 2506 to move the valve bridge (not shown) and hence both exhaust valves (not shown) to provide a normal exhaust valve lift in accordance with the cam profile (not shown) of the exhaust cam (not shown).
In exhaust brake mode, the exhaust brake control capsule 2504 is in the engine brake ON configuration to provide an exhaust brake event. In this mode, as the rocker arm arrangement 2500 pivots the control capsule 2504 causes the exhaust valve (not shown) it acts upon to open first while the rocker arm arrangement 2500 pivots through the lost motion stroke X to contact the second member 2506 to cause the valve bridge (not shown) to then open the second exhaust valve (not shown). Following the engine rocker arrangement 2500 contacting the second member 2506, the lift of both of the exhaust valves (not shown) is controlled by the second member 2506 in accordance with cam profile (not shown) of the exhaust cam (not shown). The cam profile (not shown) may, for example, provide a single stroke-exhaust lift and the arrangement may be used on cylinders 5 and 6 in the system of
It is to be understood that any feature described in relation to any one example may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the examples, or any combination of any other of the examples.
According to a first example, a cam phasing mechanism is provided. The cam phasing mechanism for a cam assembly of an internal combustion engine, the cam assembly comprising a camshaft and an actuator for opening a valve at a reference position of rotation of the camshaft. Aspects of the cam phasing mechanism are as follows:
- Aspect 1: The cam phasing mechanism comprises:
a force transfer member for interposition between the camshaft and the actuator of the cam assembly for transferring force between the camshaft and the actuator; and
an adjuster for selectively moving the force transfer member to adjust the reference position of rotation of the camshaft.
- Aspect 2: The cam phasing mechanism according to Aspect 1 of the first example, wherein the adjuster comprises a first member and a second member, wherein the first member is moveable relative to the second member for selectively moving the force transfer member relative to the second member to adjust the reference position of rotation of the camshaft.
- Aspect 3: The cam phasing mechanism according Aspect 2 of the first example, wherein the first member is continuously moveable relative to the second member for continuously adjusting the reference position of rotation of the camshaft within a predetermined range.
- Aspect 4: The cam phasing mechanism according to Aspect 2 or Aspect 3 of the first example, wherein the force transfer member is spaced from the first member by a third member.
- Aspect 5: The cam phasing mechanism according to Aspect 4 of the first example, wherein the third member is pivotable about the first member.
- Aspect 6: The cam phasing mechanism according to Aspect 4 or Aspect 5 of the first example, wherein the third member is Y-shaped such that a distal portion of the third member is a bifurcated portion to enclose the force transfer member.
- Aspect 7: The cam phasing mechanism according to any one of Aspect 2 to Aspects 6 of the first example, comprising a driving member for driving the second member of the adjuster.
- Aspect 8: The cam phasing mechanism according to Aspect 7 of the first example, wherein an axis of rotation of the driving member is perpendicular to an axis of rotation of the second member.
- Aspect 9: The cam phasing mechanism according to any preceding Aspect of the first example, wherein the first member is moveable relative to the second member by translational motion of the first member.
- Aspect 10: The cam phasing mechanism according to any preceding Aspect of the first example, wherein the force transfer member comprises a first roller for engagement with the camshaft of the cam assembly and a second roller for engagement with the actuator of the cam assembly.
- Aspect 11: The cam phasing mechanism according to Aspect 10 of the first example, wherein the first roller and the second roller are each independently rotatable about a third roller.
- Aspect 12: The cam phasing mechanism according to Aspect 10 or Aspect 11 of the first example, wherein the first roller and the second roller are coaxial.
- Aspect 13: The cam phasing mechanism according to Aspect 12 of the first example, wherein the first roller and the second roller are rotatable about a common axis, and wherein the first roller is restricted to a central location along the common axis.
- Aspect 14: The cam phasing mechanism according to any one of Aspect 10 to Aspect 13 of the first example, wherein the second roller comprises two rollers, wherein one of the two rollers is arranged on one side of the first roller and the other of the two rollers is arranged on another side of the first roller.
According to a second example, a cam assembly for an internal combustion engine and for controlling actuation of a valve is provided. Aspects of the cam assembly are as follows:
- Aspect 1: The cam assembly comprises:
a camshaft;
an actuator moveable by rotation of the camshaft for opening the valve at a reference position of rotation of the camshaft; and
a force transfer member interposed between the camshaft and the actuator for transferring force between the camshaft and the actuator;
wherein the force transfer member is selectively moveable by an adjuster to adjust the reference position of rotation of the camshaft.
- Aspect 2: The cam assembly according to Aspect 1 of the second example, wherein the force transfer member is selectively moveable either side of a reference plane between an axis of the camshaft and an axis of the actuator.
- Aspect 3: The cam assembly according to Aspect 15 or Aspect 16 of the second example, wherein the actuator comprises a first surface for avoiding contact with the force transfer member and a second surface for engaging the force transfer member.
- Aspect 4: The cam assembly according to Aspect 17 of the second example, wherein the force transfer member comprises a first roller for engaging the camshaft and a second roller for engaging the second surface of the actuator.
- Aspect 5: The cam assembly according to Aspect 18 of the second example, wherein the first roller comprises a diameter that is greater than a diameter of the second roller.
According to a third example, a valve train assembly for an internal combustion engine is provided. The valve train assembly comprising an exhaust valve and the cam assembly according to any one of Aspects 1 to 5 of the second example.
According to a fourth example, an actuation mechanism for controlling actuation of a valve of an internal combustion engine is provided. Aspects of the actuation mechanism are as follows:
- Aspect 1: The actuation mechanism comprises:
a first actuator for controlling actuation of the valve when the actuation mechanism is arranged in a first position; and
a second actuator for controlling actuation of the valve when the actuation mechanism is arranged in a second position;
wherein the first actuator and second actuator are moveable relative each other.
- Aspect 2: The actuation mechanism according to Aspect 1 of the fourth example, wherein movement of the first actuator is governed by a first driver and movement of the second actuator is governed by a second driver that is different to the first driver.
- Aspect 3: The actuation mechanism according to Aspect 2 of the fourth example, wherein the first driver comprises a mechanical force and the second driver comprises a hydraulic force.
- Aspect 4: The actuation mechanism according to any preceding Aspect of the fourth example, comprising an engagement area for mechanical engagement with a rocker arm assembly to move a rocker atm of the rocker arm assembly, wherein the engagement area comprises a portion of the first actuator and a portion of the second actuator when the actuation mechanism is arranged in the second position.
- Aspect 5: The actuation mechanism according to Aspect 4 of the fourth example wherein, the first actuator comprises a slave part and a master part that are separable from each other and the engagement area comprises a portion of the slave part of the first actuator and the portion of the second actuator and wherein the second actuator acts to maintain the valve at a substantially fixed position as the master part separates from the slave part to arrange the actuation mechanism in a third position.
- Aspect 6: The actuation mechanism according to Aspect 5 of the fourth example, wherein the slave part and the master part that are separated by a gap when the actuation mechanism is arranged in the third position.
- Aspect 7: The actuation mechanism according to Aspect 6 of the fourth example, wherein the gap is variable when the actuation mechanism is arranged between the third position and a fourth position.
- Aspect 8: The actuation mechanism according to any one of Aspect 5 to Aspect 7 of the fourth example, wherein the actuation mechanism comprises a pressure release portion for releasing fluid pressure from a working zone acting on the second actuator of the actuation mechanism to enable the second actuator and the slave part of the first actuator to move the actuation mechanism from the third position into the fourth position in which the valve is closed and the slave part and the master part of the first actuator are non-separated.
- Aspect 9: The actuation mechanism according to any preceding Aspect of the fourth example, comprising a fluid passageway comprising a fluid inlet, a working zone and a fluid outlet; wherein a volume of fluid within the working zone is variable by movement of fluid between the fluid inlet and fluid outlet.
- Aspect 10: The actuation mechanism according to any preceding Aspect of the fourth example, comprising a controller for hydraulically controlling movement of the second actuator.
- Aspect 11: The actuation mechanism according to Aspect 10 of the fourth example, wherein the controller controls release of fluid from the fluid outlet to reduce the volume of fluid within the working zone.
- Aspect 12: The actuation mechanism according to any preceding Aspect of the fourth example, wherein the first actuator is moveable within the second actuator.
According to a fifth example, a valve train assembly for an internal combustion engine is provided. The valve train assembly comprising an exhaust valve and the actuation mechanism according to any one of Aspects 1 to 12 of the fourth example for actuating the exhaust valve.
According to a sixth example, an actuation assembly for an internal combustion engine is provided. Aspects of the actuation assembly are as follows:
- Aspect 1: The actuation assembly comprises:
an actuation mechanism according to any one of Aspect 1 to Aspect 12 of the fourth example for controlling actuation of an exhaust valve; and
a motion controller for controlling actuation of an intake valve;
wherein the motion controller comprises a pressure release portion for releasing fluid pressure from a working zone acting on the second actuator of the actuation mechanism.
- Aspect 2: The actuation assembly according to Aspect 1 of the sixth example, wherein the pressure release portion is activatable by an intake camshaft.
- Aspect 3: The actuation assembly according to Aspect 15 of the sixth example, wherein the pressure release portion is independent of the opening timing of the exhaust valve.
- Aspect 4: The actuation assembly according to Aspect 15 or Aspect 16 of the sixth example, wherein the pressure release portion is a channel for communication between a fluid outlet of the actuation mechanism and a return line of a hydraulic circuit.
- Aspect 5: The actuation assembly according to any one of Aspect 14 to Aspect 17 of the sixth example, wherein the pressure release portion is configured to release pressure from the working zone between 0.5 and 0.7 mm of lift of the exhaust valve.
According to a seventh example, a motion controller for controlling movement of a valve of an internal combustion engine is provided. Aspects of the motion controller are as follows:
- Aspect 1: The motion controller comprises:
a first part for engagement with a rocker arm assembly; and
a second part for engagement with a camshaft;
wherein the motion controller is arrangeable between an unlocked state and a locked state before the valve is opened;
wherein in the unlocked state the second part is moveable towards the first part by the camshaft without imparting a lifting force to the valve to thereby delay an opening of the valve.
- Aspect 2: The motion controller according to Aspect 1 of the seventh example wherein, after the second part has been moved a pre-defined distance by the camshaft without imparting a lifting force to the valve, the second part contacts the first part to arrange the motion controller in the locked state wherein the first part and the second part are moveable as a unit by the camshaft to impart a lifting force to the valve.
- Aspect 3: The motion controller according to Aspect 1 or Aspect 2 of the seventh example, wherein a resistance to relative movement between the first part and the second part in the unlocked state is provided by a resilient member.
- Aspect 4: The motion controller according any preceding Aspect of the seventh example, wherein the first part and second part form a reservoir having a port communicable with a fluid inlet and the motion controller comprises a switch for switching the fluid inlet to a fluid outlet to release fluid from the reservoir.
According to an eighth example, a valve train assembly for an internal combustion engine is provided. Aspects of the valve train assembly are as follows:
- Aspect 1: The valve train assembly comprising an intake valve and the motion controller according to any one of Aspects 1 to 4 of the seventh example for actuating the intake valve.
- Aspect 2: The valve train assembly according to Aspect 1 of the eight example, wherein a raised profile of a camshaft is configured to move the motion controller between the unlocked state and the locked state before the intake valve is opened.
- Aspect 3: The valve train assembly according to Aspect 2 of the eight example, wherein the intake valve opens at a greater rate of lift than when a corresponding rate of lift when the intake valve is closed.
According to a ninth example, an engine braking system for an internal combustion engine comprising a plurality of engine cylinders is provided. Aspects of the engine braking system are as follows:
- Aspect 1: The engine braking system comprising a single-stroke engine brake arrangement configured to provide single stroke engine braking on at least one cylinder of the plurality of cylinders and a two-stroke engine brake arrangement configured to provide two-stroke engine braking on at least one other cylinder of the plurality of cylinders.
- Aspect 2: An engine braking system according to Aspect 1 of the ninth example wherein the single-stroke engine brake arrangement is configured to provide single-stroke engine braking on each of N1 cylinders of the plurality of cylinders and the two-stroke engine brake arrangement is configured to provide two-stroke engine braking on each of N2 other cylinders of the plurality of cylinders and wherein N1 is greater than N2.
- Aspect 3: An engine braking system according to Aspect 2 of the ninth example where N1 is a whole multiple of N2.
- Aspect 4: An engine braking system according to Aspect 2 or Aspect 3 of the ninth example wherein N1=4 and N2=2.
- Aspect 5: An engine braking system according to Aspect 4 of the ninth example wherein the internal combustion engine comprises 6 cylinders arranged in a sequence and the single-stroke engine brake arrangement is configured to provide single stroke engine braking on cylinders one to four in the sequence and the two-stroke engine brake arrangement is configured to provide two-stroke engine braking on cylinders five to six in the sequence.
It is to be understood that any Aspect described in relation to any one of the first to ninth examples may be used alone, or in combination with other Aspects described, and may also be used in combination with one or more Aspects of any other of the first to ninth examples, or any combination of any other of the first to ninth examples.
REFERENCE SIGNS LIST
- 1 cam phasing mechanism
- 2a force transfer member
- 2b adjuster
- 21 first roller
- 22 second roller
- 23 third roller
- 3 third member
- 31 lever arm
- 32 proximal portion
- 33 distal portion
- 4, 4′, 2502 first member
- 41 fourth threaded portion
- 5, 2506 second member
- 51, 71, 81 locating member
- 52 second threaded portion
- 53 third threaded portion
- 6, 6′ bearing
- 7, 124, 604, 770 housing
- 8, 1360 case
- 10 driving member
- 11 first threaded portion
- 100 cam assembly
- 110, 120, 1350, 1510 camshaft
- 111, 121, 1501-5 cam
- 112a, 112b, 122 cam lobe
- 113a, 123a base surface
- 113b, 123b, 113c raised profile
- 115, 125 camshaft axis
- 130, 2012 actuator
- 131 first surface
- 132 second surface
- 135 axis of actuator
- 200, 210, 220, 2002 push rod
- 300, 310, 320, 1520, 1530, 1540 rocker arm assembly
- 311, 321 joint
- 312, 322 ball
- 313, 323 socket
- 323a, 721 engagement face
- 400, 410, 420 valve bridge assembly
- 400a intermediary part
- 500, 510, 520, 1500 valve assembly
- 501, 511, 521, 2004 valve stem
- 502, 512, 522 valve head
- 505, 515, 525 valve
- 600 actuation assembly
- 601 accumulator
- 602, 603 supply line
- 605 accumulator piston
- 606, 607 return line
- 608 common passageway
- 610, 620 force transmitter
- 700 actuation mechanism
- 700-1 first position
- 700-2 second position
- 700-3 third position
- 700-4 fourth position
- 704, 740, 840 engagement area
- 705 damper
- 710 first actuator
- 710a slave part
- 710b master part
- 720 second actuator
- 730, 830, 831, 835b fluid inlet
- 731 intermediate passageway
- 733, 833 working zone
- 734 reserve passageway
- 735, 835a., 835c fluid outlet
- 750, 850 spool valve
- 751, 851 rotating member
- 752, 852 sliding member
- 760, 860 non-return valve
- 761, 861 moveable part
- 762 base
- 800 motion controller
- 800-1 unlocked state
- 800-2 locked state
- 800a first arrangement
- 800b second arrangement
- 800c third arrangement
- 800d fourth arrangement
- 800e fifth arrangement
- 800f sixth arrangement
- 802 pressure release portion
- 810 first part
- 811, 821 cavity
- 820 second part
- 832 port
- 862 switch
- 1000, 2000 valve train assembly
- 1100, 1110, 1120 reference timing
- 1101 early phasing
- 1102 late phasing
- 1111, 1121 valve opening
- 1112, 1122 valve closing
- 1113, 1123 maximum lift
- 1200 elongated timing
- 1210, 1410 stunted timing
- 1300 internal combustion engine
- 1301—6 engine cylinder
- 1310 single-stroke engine brake cams
- 1315 fuel pump cams
- 1320 two-stroke engine brake cams
- 1330 exhaust valve cams
- 1340 intake valve cams
- 1400 two-stroke engine brake valve timing
- 1401 first bump
- 1402 second bump
- 1530 engine brake rocker arm assembly
- 1530a, 2016a, 2018a first end
- 1530b, 2016b second end
- 1540 fixed support element
- 1542 spring
- 2000 rocker arm shaft
- 2006 exhaust valve
- 2008 engine brake control capsule
- 2008a first body
- 2008b second body
- 2009 member
- 2010, 2508 lost motion spring
- 2014 two-piece piston arrangement
- 2016 first piston piece
- 2018 second piston piece
- 2020 return spring
- 2022 engine brake actuation cam
- 2024 control camshaft
- 2026 threaded region
- 2028 compliance spring
- 2500 rocker arm arrangement
- 2504 exhaust brake control capsule
- A roller assembly region
- B first direction
- C reciprocation path
- D second direction
- E1, E2 region of overlap
- F valve phasing range
- G gap
- H valve closing direction
- J valve opening direction
- K, Q lost motion region
- L translation axis
- M1, M2, M3 motion axis
- N abutment area
- P reference plane
- R1, R2, R3 rotation direction
- S spring
- S1 first side
- S2 second side
- T deactivated exhaust event
- X lost motion stroke
Claims
1. A cam phasing mechanism (1) for a cam assembly (100) of an internal combustion engine, the cam assembly (100) comprising a camshaft (120) and an actuator (130) for opening a valve (505) at a reference position of rotation of the camshaft (120), the cam phasing mechanism (1) comprising:
- a force transfer member (2a) for interposition between the camshaft (120) and the actuator (130) of the cam assembly (100) for transferring force between the camshaft (120) and the actuator (130); and
- an adjuster (2b) for selectively moving the force transfer member (2a) to adjust the reference position of rotation of the camshaft (120).
2. The cam phasing mechanism (1) according to claim 1, wherein the adjuster (2b) comprises a first member (4) and a second member (5), wherein the first member (4) is moveable relative to the second member (5) for selectively moving the force transfer member (2a) relative to the second member (5) to adjust the reference position of rotation of the camshaft (110).
3. The cam phasing mechanism (1) according claim 2, wherein the first member (4) is continuously moveable relative to the second member (5) for continuously adjusting the reference position of rotation of the camshaft (120) within a predetermined range.
4. The cam phasing mechanism (1) according to claim 2, wherein the force transfer member (2a) is spaced from the first member (4) by a third member (3).
5. The cam phasing mechanism (1) according to claim 4, wherein the third member (3) is pivotable about the first member (4).
6. The cam phasing mechanism (1) according to claim 4, wherein the third member (3) is Y-shaped such that a distal portion (33) of the third member (3) is a bifurcated portion to enclose the force transfer member (2a).
7. The cam phasing mechanism (1) according to claim 2, comprising a driving member (10) for driving the second member (5) of the adjuster (2b).
8. The cam phasing mechanism (1) according to claim 7, wherein an axis of rotation of the driving member (10) is perpendicular to an axis of rotation of the second member (5).
9. The cam phasing mechanism (1) according to claim 1, wherein the first member (4) is moveable relative to the second member (5) by translational motion of the first member (4).
10. The cam phasing mechanism (1) according to claim 1, wherein the force transfer member (2a) comprises a first roller (21) for engagement with the camshaft (120) of the cam assembly (100) and a second roller (22) for engagement with the actuator (130) of the cam assembly (100).
11. The cam phasing mechanism (1) according to claim 10, wherein the first roller (21) and the second roller (22) are each independently rotatable about a third roller (23).
12. The cam phasing mechanism (1) according to claim 10, wherein the first roller (21) and the second roller (22) are coaxial.
13. The cam phasing mechanism (1) according to claim 12, wherein the first roller (21) and the second roller (22) are rotatable about a common axis, and wherein the first roller (21) is restricted to a central location along the common axis.
14. The cam phasing mechanism (1) according to claim 10, wherein the second roller (22) comprises two rollers, wherein one of the two rollers is arranged on one side of the first roller (21) and the other of the two rollers is arranged on another side of the first roller (21).
15. A cam assembly (100) for an internal combustion engine and for controlling actuation of a valve (505), the cam assembly (100) comprising:
- a camshaft (120);
- an actuator (130) moveable by rotation of the camshaft (120) for opening the valve (505) at a reference position of rotation of the camshaft (120); and
- a force transfer member (2a) interposed between the camshaft (120) and the actuator (130) for transferring force between the camshaft (120) and the actuator (130); wherein the force transfer member (2) is selectively moveable by an adjuster (2b) to adjust the reference position of rotation of the camshaft (120).
16. The cam assembly (100) according to claim 15, wherein the force transfer member (2a) is selectively moveable either side (S1, S2) of a reference plane (P) between an axis (115) of the camshaft (120) and an axis (135) of the actuator (130).
17. The cam assembly (100) according to claim 15, wherein the actuator (130) comprises a first surface (131) for avoiding contact with the force transfer member (2a) and a second surface (132) for engaging the force transfer member (2a).
18. The cam assembly (100) according to claim 17, wherein the force transfer member (2a) comprises a first roller (21) for engaging the camshaft (120) and a second roller (22) for engaging the second surface (132) of the actuator (130).
19. The cam assembly (100) according to claim 18, wherein the first roller (21) comprises a diameter that is greater than a diameter of the second roller (22).
20. A valve train assembly (1000) for an internal combustion engine, the valve train assembly (1000) comprising an exhaust valve and a cam assembly (100) for actuating the exhaust valve, the cam assembly (100) comprising:
- a camshaft (120);
- an actuator (130) moveable by rotation of the camshaft (120) for opening the valve (505) at a reference position of rotation of the camshaft (120); and
- a force transfer member (2a) interposed between the camshaft (120) and the actuator (130) for transferring force between the camshaft (120) and the actuator (130); wherein the force transfer member (2) is selectively moveable by an adjuster (2b) to adjust the reference position of rotation of the camshaft (120).
Type: Application
Filed: Sep 19, 2019
Publication Date: Oct 14, 2021
Inventor: Majo Cecur (Turin)
Application Number: 17/277,802