WO2005042930A2 - Brennkraftmaschine - Google Patents
Brennkraftmaschine Download PDFInfo
- Publication number
- WO2005042930A2 WO2005042930A2 PCT/AT2004/000372 AT2004000372W WO2005042930A2 WO 2005042930 A2 WO2005042930 A2 WO 2005042930A2 AT 2004000372 W AT2004000372 W AT 2004000372W WO 2005042930 A2 WO2005042930 A2 WO 2005042930A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- valve
- particular according
- internal combustion
- combustion engine
- gas exchange
- Prior art date
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
- F01L13/0015—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque
- F01L13/0031—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque by modification of tappet or pushrod length
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/12—Transmitting gear between valve drive and valve
- F01L1/14—Tappets; Push rods
- F01L1/143—Tappets; Push rods for use with overhead camshafts
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
- F01L13/0005—Deactivating valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L9/00—Valve-gear or valve arrangements actuated non-mechanically
- F01L9/10—Valve-gear or valve arrangements actuated non-mechanically by fluid means, e.g. hydraulic
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L9/00—Valve-gear or valve arrangements actuated non-mechanically
- F01L9/20—Valve-gear or valve arrangements actuated non-mechanically by electric means
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L2301/00—Using particular materials
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L2301/00—Using particular materials
- F01L2301/02—Using ceramic materials
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L2303/00—Manufacturing of components used in valve arrangements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L2820/00—Details on specific features characterising valve gear arrangements
- F01L2820/01—Absolute values
Definitions
- the invention relates to an internal combustion engine with a variable valve actuation device for a gas exchange valve which can be actuated via a cam and a tappet, the cam acting on the gas exchange valve via an actuating member which can be pivoted transversely to the camshaft axis between at least two positions. Furthermore, the invention relates to an internal combustion engine with a valve actuating device with a tappet for a cam-operated gas exchange valve, the tappet being profiled and having a contact surface facing the cam, which has at least a first and a second section. The invention also relates to an internal combustion engine with at least one valve insert for at least one gas exchange valve of a gas exchange channel arranged in a cylinder head. The invention further relates to a method for operating an internal combustion engine with preferably electrohydraulic, fully variable valve train.
- the valve actuators are typically designed to achieve maximum power output at high engine speeds.
- the profiles of the cams of the gas exchange valves are designed so that high gas flows can be achieved at high speeds, with maximum valve strokes and opening times being designed for the highest possible gas flows. At low speeds, however, the long opening times of the gas exchange valves reduce the degree of delivery, which leads to lower torques and efficiency.
- EP 0 292 185 B1 proposes to design the cup tappet in a profiled manner, the angular orientation of the profiled end face with respect to the axis of rotation being able to be changed by rotating the valve tappet.
- the cup tappet has a tiltable disc, which can be tilted by rotating the cam about a swivel joint in the area of the center of the cup tappet. It is disadvantageous that a relatively high design effort is required to rotate the tappet.
- EP 1 209 326 A2 discloses a variable valve actuation device for a gas exchange valve actuated by a cam via a bucket tappet, an actuation element essentially configured as a plate being arranged between the cam and the valve stem of the gas exchange valve, said actuation element being in one position by means of a hydraulic actuator can be fixed, wherein a locking piston is pressed against the actuator.
- a hydraulic actuator When the hydraulic actuator is deactivated, part of the cam stroke is absorbed by the actuator pivoted into a second position, whereby the effective valve lift of the gas exchange valve is less than when the hydraulic actuator is activated.
- the piston axis of the locking piston is arranged parallel to the valve axis within the tappet.
- this has a disadvantageous effect on the height of the cup tappet.
- valve lift curve In the case of non-variable valve actuation devices, the design of the valve lift curve is limited by the shape of the cam profile for a given base circle diameter, as far as the maximum valve lift in relation to the minimum valve opening duration is concerned, especially in valve drives without valve play compensation.
- the pre-cam To ensure smooth opening and closing of the gas exchange valve when the engine is cold and warm, the pre-cam must have a minimum length to overcome the valve clearance. If this minimum length is not guaranteed, the line of contact between the cam and the tappet at the beginning of the valve stroke is no longer in the area of the pre-cam and thus far outside the center of the cup, as a result of which the cam hits the contact surface of the tappet and extremely high acceleration forces occur, which are very high Cause wear and are noticeable through high valve operating noises.
- the valve opening duration of the gas exchange valve primarily depends on the angle between the front cam and the cam tip. If the valve opening time is to be reduced, the tip radius must be smaller if the cam stroke and flank radius remain the same. However, the tip radius of the cam tip cannot be reduced arbitrarily, because its reduction also increases the Hertzian surface pressure. To avoid excessive Hertzian surface pressure, the only option left is to reduce the cam stroke. For a given base circle radius, changing the cam shape means that the opening time can only be reduced while simultaneously reducing the maximum cam stroke. However, this has the disadvantage that there is a significant loss of performance in the upper speed range.
- Valve seats for gas exchange valves of internal combustion engines are often formed by valve seat rings fixedly arranged in the cylinder head. Since the valve seat area is a thermally highly stressed region of the cylinder head, sufficient heat dissipation is required. When using valve seat rings, however, there is the problem that cooling channels formed in the cylinder head cannot be brought close enough to the valve seat area. From DE 30 32 276 AI valve seat rings with cooling channels formed between the valve seat ring and the cylinder head are known, however, there is a risk that leaks can occur. Another disadvantage of valve seat rings is that they take up a relatively large amount of space and the material webs between the valve openings have to be made very narrow, which increases the risk of cracks.
- valve seat insert made of ceramic material is cast into the cylinder head and extends from the valve seat to the valve guide area. It is disadvantageous that the production of such ceramic components is relatively expensive. Cast-in valve seat inserts also have the disadvantage that they cannot be replaced in the event of a repair.
- Cast valve seat inserts for cylinder heads of large engines with an integrated valve seat and an integrated valve guide are also known from US Pat. No. 4,008,695 A. However, these are not suitable for smaller engines, for example vehicle engines.
- the control of the gas exchange valves by means of camshafts only allows control times and / or stroke of the gas exchange valves to be set to a limited extent in accordance with the operating conditions of the internal combustion engine.
- both the stroke of the gas exchange valves and its control time can in principle be set freely. This can improve the operating behavior of the internal combustion engine, its specific fuel consumption and its emissions.
- Electro-hydraulic valve control devices for realizing a fully variable valve actuation are known from DE 101 27 205 AI and DE 101 34 644 AI. Compared to variable mechanical or variable electromagnetic valve control, the variable electro-hydraulic valve control offers advantages in terms of charge movements and pumping losses.
- valve pockets molded into the piston can increase the valve lift height in the area of the top dead center of the gas exchange and thus improve the fresh air purging, but such deformations in the piston surface sometimes have a disadvantageous effect on the combustion.
- the object of the invention is to avoid these disadvantages and to increase the power in the lower speed range in the simplest possible manner or to increase torque and efficiency in the lower speed range without sacrificing performance in the upper speed range.
- the variable valve actuation device should require the smallest possible combustion chamber.
- a further task is to ensure adequate cooling in the valve seat area in the simplest possible manner, it being possible to subsequently replace defective valve seat inserts.
- Another object of the invention is to improve consumption and emissions, particularly in the full load range.
- the actuating member in its first position defining a first valve stroke can be fixed by a locking piston and a second valve stroke defining a second position of the actuating member is smaller than the first valve stroke
- the piston axis of the locking piston preferably being approximately normal to the valve axis is arranged and preferably intersects the valve axis.
- the locking piston arranged approximately normal to the valve axis in a transverse bore thus becomes approximately normal to a reference plane spanned by the camshaft axis and the valve stem axis on the actuating member.
- the additional space required in the cup tappet corresponds approximately to the diameter of the locking piston and is very small, so that the valve actuation device can be made very compact.
- the gas passing through the gas exchange valve is influenced primarily by changing the control time, while the maximum stroke of the gas exchange valve remains largely unchanged. This has the advantage that high engine power is available due to the unchanged large maximum valve lift, particularly in the lower speed range.
- the actuating member can roll with a lower contact surface facing away from the cam on a corresponding counter surface of the cup tappet, it preferably being provided that the lower contact surface of the actuating member has a rolling contour with a convexly curved surface.
- the counter surface of the cup tappet has a convexly curved rolling contour.
- the actuating member is rotatably mounted about a pin which is fixed to the tappet, the bearing bore of the actuating member being formed by an elongated hole.
- the locking piston is arranged on the same side as the axis of rotation with respect to a reference plane formed by the camshaft axis and the valve axis.
- the axis of rotation of the actuating member is located approximately in the area of the intersection between the piston axis of the locking piston and the valve axis, but is preferably slightly spaced from it. It can be provided that the distance between the geometric axis of rotation and the valve axis corresponds to a maximum of half the tappet radius, preferably a maximum of the valve stem diameter, particularly preferably a maximum of half the valve stem diameter.
- the actuating element essentially has the shape of a wedge.
- the actuating member has on its side facing the locking piston a locking opening shaped corresponding to the locking piston, into which the locking piston engages in the first position of the actuating member. In this way, a reliable fixing of the actuator in its first position is guaranteed.
- the actuating member is designed without a bearing bore and is therefore loosely connected to the tappet body of the cup tappet.
- the preferably platelet-shaped actuator rolls with its lower contact surface on a rolling contour formed by the counter surface of the tappet body, the instantaneous geometric axis of rotation of the actuator approaching the reference plane when pivoting from the first position to the second position.
- the actuating member can be tilted about an edge formed by the tappet body and the axis of rotation is thus formed by the edge of the tappet body.
- the actuating member has at least one, preferably two, circular segment-shaped guide lugs which are guided in corresponding grooves in the tappet body.
- the locking piston is located in a transverse bore of the tappet body of the bucket tappet which penetrates the reference plane. leads.
- the locking piston acts on a stop on the underside of the actuator and prevents its tilting movement.
- the tilting movement of the actuating member is released, wherein the actuating member can have a recess on its underside for release from the locking piston.
- the locking piston can be activated hydraulically, mechanically or pneumatically.
- the first and second sections are designed to be inclined to one another, the second section preferably being convexly inclined with respect to the first section which is preferably arranged normal to the stroke axis of the bucket tappet. It is preferably provided that the transition area between the first and second sections is spaced from a reference plane spanned by the stroke axis and the camshaft axis, the distance preferably corresponding to a maximum of half the tappet radius, preferably a maximum of the valve stem diameter, particularly preferably a maximum of half the valve stem diameter.
- the line of intersection between the contact surface of the first section and the second section runs essentially parallel to the reference plane.
- the contact surface can have a first radius of curvature of approximately 50 mm at most. It is particularly advantageous if the contact surface of the second section is convexly curved with a radius of curvature of at least approximately 50 mm. In a particularly advantageous embodiment variant of the invention it is provided that the angle of inclination between the first and the second section is between approximately 185 ° and 210 °, preferably between approximately 190 ° and 200 °.
- the valve stroke curve can be significantly influenced by varying the eccentricity, the first radius of curvature and the second radius of curvature, as well as the angle ⁇ and the valve clearance.
- the bucket tappet must be installed so that it cannot twist.
- the gas exchange valve closes earlier or later.
- this is caused primarily by the bevel of the rolling contour on one side, whereby this must start eccentrically with the largest possible radius.
- the eccentricity is of great importance because the contact line between the cam and the cup tappet moves from the inside to the outside during one revolution of the camshaft, i.e. from the stroke axis to the cup edge zone, and then to the opposite lying on the edge of the cup to cross the entire cup area and return from here back to the stroke axis, i.e. towards the center of the cup.
- valve seat insert extends from a valve seat area to a valve guide area for the gas exchange valve, the valve seat insert preferably being made of sheet metal, preferably sheet steel.
- the valve seat insert can be formed from a sheet metal blank in a simple manufacturing process. On the one hand, this has the advantage that the valve seat insert can be mass-produced very inexpensively.
- a sheet metal part has a better thermal conductivity than a ceramic part, so that particularly good heat dissipation from thermally stressed regions is possible.
- valve seat insert is connected to the cylinder head in an interchangeable manner, the valve seat insert preferably being pressed into the cylinder head. If necessary, a worn valve seat insert can be removed from the cylinder head and a new valve seat insert inserted.
- valve seat insert is fixedly connected to a valve guide which accommodates the shaft of the gas exchange valve and is fixedly arranged in a receiving bore of the cylinder head.
- the valve seat insert can be made in one piece with the valve guide or separately from it.
- valve seat insert has an annular extension surrounding the valve stem of the gas exchange valve, which is inserted, preferably pressed, into the receiving bore of the cylinder head for the valve guide.
- valve seat insert between the valve seat area and extension has a dome-like, continuous connecting wall, the connecting wall in the area of the gas exchange channel having a passage opening corresponding to the cross section of the gas exchange channel ,
- the connecting wall in the area of the gas exchange channel having a passage opening corresponding to the cross section of the gas exchange channel
- valve seat insert between the valve seat area and the extension has a dome-like connecting wall with openings, the connecting wall in the area of the gas exchange channel having a passage opening corresponding to the cross section of the gas exchange channel.
- the openings in the connecting wall enable heat exchange between the gas exchange duct and the cylinder head.
- At least one connecting web is preferably formed between the extension and the valve seat region, preferably at least one connecting web being arranged in the tongue region of the spiral duct.
- the connecting webs are shaped in a flow-favorable manner in the inflow direction and have, for example, a guide vane profile.
- the swirl inlet flow can be favored by the guide vanes shaped in the manner of a guide vane.
- the extension is designed to support the swirl in the region of the valve chamber.
- the flow losses can be kept as small as possible if the extension in the area of the gas exchange duct surrounds the shaft of the gas exchange valve as closely as possible.
- Consumption and emissions in full-load operation can be decisively improved if at least one inlet valve and / or one outlet valve is opened or closed discontinuously at least in the area of top dead center of the gas exchange. Due to the discontinuous or discontinuous actuation of the intake and exhaust valves, the gas exchange can be optimally adapted to the combustion requirements. This means that combustion can be optimized in terms of consumption, emissions and / or load in all load ranges.
- valve lift is kept essentially constant between the stages.
- an essentially flat ramp is formed between the stages, in which the inlet or outlet valve does not change its valve lift.
- the intake valve lift and / or the exhaust valve lift in the area of top dead center are moved simultaneously and in the same direction as the piston, with a predefined minimum distance between the piston and the intake valve or exhaust valve preferably not less than 0.8 mm. Because the valve lift of the movement following the piston, the inlet valve or the outlet valve can “dive” under the piston while maintaining a relatively large safety distance.
- the inlet valve is opened up to a first opening position before top dead center of the gas exchange and further up to a second opening position after top dead center, the valve lift being constant in the first opening position in the area of top dead center is maintained, wherein the valve lift of the inlet valve is preferably reduced from the second open position into a third open position, and wherein the valve lift of the third open position is kept constant for a predefined period before the inlet valve is finally closed.
- the intake valves are actuated again, which results in a further valve lift from the first to the second open position, which optimizes the inflow to the cylinder charge.
- the exhaust valve is opened into a first opening position at the beginning of the exhaust stroke, the valve stroke of the first opening position being kept constant for a predefined period and then being further expanded into a second opening position, the valve stroke of the exhaust valve preferably being immediately before top dead center of the charge change from the second opening position to a third opening position is reduced, and wherein the valve lift in the third opening position is kept constant for a predefined duration.
- the outlet valve is closed from the second open position in the area of the top dead center of the charge change, preferably immediately after top dead center of the charge change.
- the inlet valve lift can be precontrolled to a stroke value that is not critical for the form of collision by means of the electro-hydraulic valve train. This improves the purging behavior, whereby controlled internal residual gas recirculation is possible.
- Optimal fresh air purging can thus be achieved in the area of the top dead center of the charge change, valve pockets in the piston being dispensed with or at least the depth of valve pockets in the piston being substantially reduced.
- the overlap area of the lifting curves in the area of the top dead center of the charge exchange can be optimized to implement internal residual gas control in the partial load range, and on the other hand the purging behavior at full load can be significantly improved. Due to the optimally designed intake stroke during the intake phase, gas exchange losses can be significantly reduced and the full load potential can be significantly increased. Simplified collision models can be used due to the quilted valve lifting of exhaust and intake valves.
- FIG. 2a shows a variable valve actuation device in a second embodiment variant in a locked position
- FIG. 3 shows a variable valve actuation device in a third embodiment variant in a locked position
- Figure 4 shows this valve actuation device in a section along the line IV-IV in Fig. 3.
- FIG. 9 shows a valve actuation device according to the invention in a section
- FIG. 11 shows a stroke diagram of an internal combustion engine with the valve actuation device according to the invention
- Fig. 12 is a stroke diagram of a conventional valve operating device; 13 shows a stroke diagram of the valve actuation device according to the invention in comparison with a conventional valve actuation device;
- FIG. 14 shows a cylinder head with a valve seat insert according to the invention in section in a first embodiment variant
- FIG. 15 shows a cylinder head with a valve seat insert according to the invention in section in a second embodiment variant
- FIG. 16 shows the valve seat insert in section along the line XVI-XVI in FIG. 15;
- FIG. 17 shows a valve lift diagram for a first embodiment of the method according to the invention.
- FIG. 18 shows a valve lift diagram for a second embodiment of the method according to the invention.
- FIGS. 1 to 7 each show a variable valve actuation device 1 for a gas exchange valve 2 of an internal combustion engine, the gas exchange valve 2 being actuated via a cam 3 and a cup tappet 4.
- the cam 3 acts on the tappet 4 via an actuator 5 which can be pivoted about a geometric axis of rotation 6.
- the actuating member can be pivoted between a first position A and a second position B and can be fixed in the first position A by a locking piston 7 that can be actuated hydraulically, for example.
- the actuating member 5 has a wedge-shaped cross section and is rotatably supported by means of a bearing bore 8 in the actuating member 5 about a pin 10 fixed in the tappet body 9 of the bucket tappet 4 ,
- the geometric axis of rotation 6 and the locking piston 7 are arranged on the same side of a reference plane 11 spanned by the valve axis 2a and the camshaft axis 3a.
- the locking piston 7 is slidably mounted in a transverse bore 12 of the tappet body 9, the piston axis 7a being arranged approximately normal to a reference plane 11 spanned by the valve axis 2a and the camshaft axis 3a. Piston axis 7a and axis of rotation 6 are located approximately in a normal plane 24 on the valve axis 2a. This enables a very compact design of the valve actuating device 1.
- the blocking piston 7 can be acted upon by pneumatic or hydraulic pressure via pressure lines 13, wherein when the blocking piston 7 is activated, it can be locked in a lateral latching opening 14 of the actuating element 5 in order to fix it in the first position A. When the pressure is released, the locking piston 7 is brought out of the latching opening 14 into its rest position by a restoring element (not shown further), as a result of which the actuator 5 can be pivoted into its second position B according to FIG. 2.
- the gas exchange valve 2 In the first fixed position A of the actuator 5, the gas exchange valve 2 is opened to the maximum according to the cam shape of the cam 3. In the second position B of the actuator 5, the valve lift of the gas exchange valve 2 is reduced in accordance with the tilting movement of the actuator 5.
- the adjustment of the actuator 5 from the first A to the second position B and back takes place automatically by the rotation of the cam 3, the actuator 5 being rotated from the first position A to the second position B when the cam 3 runs onto the actuator 5 and when the cam 3 runs, the actuator 5 is moved again from the second position B to the first position A.
- FIGS. 2a, 2b differs from the embodiment variant shown in FIGS. 1a, 1b in that the bearing bore 8 is designed as an elongated hole.
- the underside facing away from the cam 3 and facing the valve stem 2b of the gas exchange valve 2, forming a lower contact surface 15, can have a rolling contour with a convexly curved surface, which rolls on a corresponding counter surface 16 of the tappet body 9 when the actuating member 5 from the first position A in the second position B is moved.
- FIGS. 3 to 7 show a third embodiment variant, the actuating member 5 lying loosely on the tappet body 9 and thus no pin for fixing the actuating member 5 with the tappet body 9 is provided.
- the actuating member 5 is essentially designed as a plate and has on both sides of a plane of symmetry 17 normal to the camshaft axis 3a through the valve axis 2a essentially circular segment-shaped guide lugs 18, which can be used accordingly shaped circularly curved grooves 19 of the tappet body 9.
- the actuating member 5 is secured against excessive displacement normal to the valve axis 2a by the guide lugs 18 and the grooves 19, a defined displacement being permissible in order to ensure a perfect roll-over.
- the lower contact surface 15 of the actuating member 5 is flat, at least in the contact area with the tappet body 9, and can roll on a convex counter surface 16 designed as a rolling contour, the actuating member 5 moving from the first position A shown in FIG. 3 to that shown in FIG. 5 can roll second position when the locking piston 7 releases the movement of the actuator 5.
- the locking piston 7 is slidably mounted in the region of symmetry 17 in a transverse bore 12 of the plunger body 9 penetrating the reference plane 11, the locking piston 7 being loaded by a spring 20 in the direction of the locking position A shown in FIG. 3.
- the actuator 5 rests with a stop 21 on the locking piston 7, so that any tilting movement of the actuator 5 is prevented.
- the locking piston 7 is moved pneumatically or hydraulically against the force of the spring 20 into its release position shown in FIG. 5, the actuating member 5 can tilt from the first position A to the second position B, so that part of the one specified by the cam 3 Maximum valve lift is absorbed by the tilting movement of the actuator 5 and the gas exchange valve 2 is thus only partially opened.
- the current geometric axis of rotation 8 moves in the direction of the reference plane 11.
- the distance e between the geometric axis of rotation 8 and the valve axis 2a corresponds in the exemplary embodiments to approximately half the diameter d of the valve stem 2b.
- the actuator 5 In the locking position A shown in Fig. 3, the actuator 5 rests with a stop 21 on the locking piston 7, whereby any tilting movement is prevented. In order to enable the largest possible tilt angle between the first position A and the second position B and to provide the necessary clearance between the actuator 5 and the locking piston 7, the actuator 5 has a recess 22 on its underside 15.
- a screw plug is designated by reference numeral 23.
- FIG. 8 shows a valve lift diagram for the variable valve actuation devices 1 described, the valve lift h being plotted over the crank angle CA.
- Curve 10 shows valve stroke h in blocking position A
- curves 31 and 32 show valve strokes h in release positions B for different eccentricities e, the eccentricity e in curve 31 being smaller than in curve 32.
- FIGS. 9 and 10 show a bucket tappet 101, which is rotatably mounted in a tappet cylinder 117 for a valve actuation device 103 actuated by a cam 102.
- the contact surface 104 with the cam 102 has a special shape and is approximately normal to the stroke axis 105 of the Gas exchange valve 106 arranged flat first section 107 and a concave inclined second section 108 divided.
- Reference number 109 denotes a normal plane on the lifting axis 105.
- the second section 108 may have a flat or curved surface.
- the second section 108 or a tangential plane ⁇ of the second section 108 includes an angle ⁇ of approximately 185 ° to 210 ° with the first section 107.
- the intersection line 111 in the transition area between the first section 107 and the second section 108 extends eccentrically with respect to the stroke axis 105 and is spaced apart from a reference plane 115 spanned by the stroke axis 105 and the camshaft axis 102a, the eccentricity e "preferably being smaller than that half the radius R of the tappet 104 and preferably corresponds to approximately half the diameter d 'of the valve stem of the gas exchange valve 106.
- a first radius of curvature R1' is formed between the first and the second section 107, 108, which is between approximately 1 mm and The radius of curvature of the surface of the second section 108 is denoted by R2 1 and is between approximately 50 mm and 1000 mm.
- the bucket tappet 101 must be slidably mounted in the cylinder head 112 to prevent it from rotating. Depending on the cam rotation direction 113, either an earlier closing or a later opening of the gas exchange valve 106 is achieved. This is caused - with a given valve clearance - primarily by a bevel of the rolling contour of the cup tappet 101 formed on one side by the second section 108, said eccentric with the largest possible second radius R2 1 by the value e "with respect to the stroke axis 105 from the first Section 107.
- the influence of the eccentric act e 1 can be seen from the stroke diagram in FIG. 11, the valve stroke H being plotted in each case over the crank angle CA.
- Curve 120 shows the valve stroke curve H for a flat tappet.
- the curves 121 and 122 show the valve stroke curve H for a cup tappet profiled according to FIGS. 9 and 10, the eccentricity e 1 being greater in the curve 122 than in the curve 121.
- the Profiling the tappet 101 with the second section 108 which is convexly inclined with respect to the first section 107, exerts a large influence on the control time, in the present case on the closing time, but only a slight influence on the maximum valve lift.
- control times could also be reduced by shaping the cam 102.
- shape of the cam 102 is usually limited for a given base circle radius r 1 , as far as the maximum valve lift in relation to the minimum valve opening duration is concerned, especially in the case of cam profiles for valve trains without valve clearance compensation.
- the necessary so-called ramp 117 (pre-cam) of the cam 102 must have a certain minimum length to overcome the valve clearance.
- the valve opening duration of a cam 102 is essentially determined by the angular range between the pre-cam and post-cam 117, 118. To reduce the valve opening duration, the tip radius R SP of the cam 102 must be reduced while the cam stroke and flank radius of the cam 102 remain the same. The reduction of the tip radius R SP is limited by increasing Hertzian surface pressure, so that a further reduction in the control time is only possible with a simultaneous reduction of the cam stroke.
- valve 12 shows two valve stroke profiles 123, 124 with similar loads on the valve train, the opening duration being significantly shorter in curve 124 than in curve 123.
- the maximum valve stroke must be significantly reduced.
- the valve opening area is not only reduced by the shortened opening time, but also and above all by the reduction in the cam stroke that is necessary.
- This difference in the valve opening area is illustrated in FIG. 13, the curves 122 and 124 having the same opening durations being shown in a stroke diagram. are shown to each other.
- the curve 124 thus shows the reduced opening time for a flat cup tappet, the curve 122 for a cup tappet 101 profiled according to the invention.
- valve elevation curve 122 with the profiled cup tappet 101 is accompanied by a somewhat later opening of the valve due to the eccentricity e ', as shown in FIG 11 can be seen, curves 122 and 124 were placed for 0.3 mm valve clearance (h s ) at the same opening and closing time.
- the valve opening surface 130 obtained by using the profiled tappet 101 can be seen clearly in FIG. 13.
- the higher maximum lift by using the profiled bucket tappet 101 results in an additional output of approximately 10% and more in the upper one speed range.
- the profiled bucket tappet 101 can thus prevent the typical drop in torque in the upper speed range, in particular in internal combustion engines with two lift valves 106 per cylinder, and a considerable increase in performance can thus be achieved.
- At least one valve insert 202 for a gas exchange valve 203 for controlling the flow in a gas exchange channel 204 is arranged in a cylinder head 201, as can be seen from FIGS. 14 to 16.
- the valve seat insert 202 is made of sheet metal, for example sheet steel, and extends from the valve seat area 205 to a valve guide area 206.
- the valve seat insert 202 has an annular extension 207 in the area of the valve guide area 206, which is inserted, for example pressed, into a receiving bore 209 of the cylinder head 201 receiving the valve guide 208.
- the valve seat insert 202 can be firmly connected to the valve guide 208, for example glued, soldered, screwed or the like. It is also conceivable to form the valve seat insert 202 in one piece with the valve guide 208.
- valve seat insert 202 has a connecting wall 210 between the extension 207 and the valve seat region 205, which is shaped corresponding to the wall 211 of the gas exchange channel 204.
- An insulating gap 212 can be formed between the connecting wall 210 and the wall 211 of the gas exchange channel 204.
- valve seat insert 202 is inserted into the cylinder head 201 from the combustion chamber side together with the valve seat region 205 forming the valve seat cone 205a.
- the connecting wall 210 has a passage opening 213 for air or exhaust gas.
- the extension shown in FIG. guide variant is suitable for neutral, inclined, tangential or outlet ducts.
- connection between the valve seat region 205 and the extension 207 shows an embodiment variant for spiral channels, only connecting webs 214 being provided as a connection between the valve seat region 205 and the extension 207.
- One of the webs 214 is positioned in the area of the tongue 215 of the spiral channel 204a.
- the connecting webs 214 can be shaped like a guide vane.
- the connecting webs 214 are shaped as closely as possible to the valve plate 203a and the connection between the annular extension 207 and the connecting webs 214 lies approximately in the middle of the valve chamber 216.
- the extension 207 thus encloses the valve stem 203b as closely as possible between the valve guide region 206 and the connecting webs 214.
- the material for the seat cone 205a is chosen to be as thin as possible in order to keep the space gained as large as possible compared to a conventional seat ring. Appropriate wear resistance and heat resistance are also a requirement.
- the advantages of this solution are, in particular, the low manufacturing costs for mass production compared to conventional seat rings.
- the technical gain lies in the drastically reduced space requirement of the valve seat ring, whereby the cooling conditions can be significantly improved, cracks can be avoided by the enlarged material webs in the cylinder head or, especially in the case of two-valve engines, the valve disks can be designed larger than before.
- a further effect can be achieved with the exhaust valve, where isolation is achieved by means of a targeted insulating gap 210 between the duct wall and the valve insert and the heating of the cylinder head is reduced.
- FIG. 17 shows a valve lift diagram, the lift hi of the intake valves and the lift h E of the exhaust valves being plotted against the crank angle CA.
- OT L w denotes the top dead center of the charge change.
- intake valves and exhaust valves are opened or closed discontinuously, that is to say step by step.
- the inlet valve is opened in two stages hu and h ⁇ 2 , a flat ramp IR1 being formed in the region of the first opening position hi of the inlet valve between the two stages hu and h ⁇ 2 , during which the Valve stroke h ⁇ is kept essentially constant.
- a second ramp follows the second stage h ⁇ 2 IR2 in the area of the second opening position h ⁇ R2 of the inlet valve, during which the inlet valve is kept at a constant stroke hi for a predefined period of time t T2 .
- the stroke hi of the inlet valve is brought in a third stage h 3 to a third opening position h TR3 corresponding to the ramp IR3 and this third opening position h 3 is kept constant for a predefined period of time t I3 .
- the inlet valve is then closed from the third opening position in a fourth stage h M.
- the outlet valve is also opened or closed in several steps, a flat ramp ER1 being formed in the region of the first opening position h E Ri of the outlet valve between the first stage h E ⁇ and the second stage h E2 , in which the stroke h E des Exhaust valve is kept constant for a predefined period of time t E ⁇ .
- the outlet valve is held in its second position h ER2 in accordance with the ramp ER2 on the maximum valve lift, this position being kept constant for a predefined period of time t E2 .
- the valve lift of the exhaust valve is then reduced in a third step h E3 to a third opening position h ER3 corresponding to the ramp ER3, this third opening position h ER3 being kept constant for a certain time t E3 .
- the outlet valve is then closed, for example at top dead center OT L W of the gas exchange in a fourth stage h E4 .
- the piston stroke is indicated by line 301. It can be clearly seen from the figure that both the intake and exhaust valve curves h E , hi essentially follow the piston stroke curve 301 in the area of the top dead center OT v of the gas exchange, the valve lift hi of the intake valve and the Valve stroke h E of the exhaust valve is kept at a constant value, while maintaining a minimum distance from the piston.
- inlet and / or outlet valves can be moved in the same direction as the piston, for example approximately synchronously with the piston, in the region of the top dead center OT w of the charge exchange, as a result of which the inlet or outlet valves virtually “dive under the piston” ".
- This variant is demonstrated in FIG. 17 by dotted lines for the stroke h E of the exhaust valve.
- the outlet valve from the third opening position h E 3 is not closed in the fourth stage h E4 , but is opened again in a fourth stage h E4 ', with a fourth opening position h ER4 ' corresponding to the ramp ER4 1 at the fourth stage h E4 ' then, in which the opening is kept constant for a certain period of time t E4 '.
- This is followed in a fifth step h E5 'either by a definitive closing of the exhaust valve or a reduction in the stroke H E to a fifth opening position h ER5 "corresponding to the ramp ER5".
- the exhaust valve is finally closed in a sixth stage h E6 ".
- the process of immersion is shown in detail in FIG.
- the individual stages are hi, h 2 , h 3 , h 4 , h 5 , h 6 , the ramps with Rl, R2, R3, R4, R5 and the open positions during the period ti, t 2 , t 3 , t 4 , t 5 with h Ri , h R2 , h R2 , h R3 , h R5 .
- the fully variable valve actuation with stepped stroke curves h ⁇ , h E realized by means of an electro-hydraulic valve train, enables on the one hand an optimal purging of the combustion chamber in the full load range and on the other hand an exact control of the residual gas quantity in the partial load range by optimizing the overlap areas of the stroke curves hi, h E.
- gas exchange losses can be reduced and the full load potential increased.
- the graduated valve lift in the area of the gas exchange enables particularly good flushing behavior, valve pockets in the piston being at least substantially reduced or valve pocket pistons even being dispensed with. This allows the combustion chamber to be optimally designed for combustion.
- references used in the subclaims indicate the further development of the subject matter of the skin claim through the characteristics of the respective subclaim; they are not to be understood as a waiver of the achievement of an independent, objective protection for the characteristics of the related subclaims.
- the invention is also not limited to the exemplary embodiment (s) of the description. Rather, numerous changes and modifications are possible within the scope of the invention, in particular those variants, elements and combinations and / or materials which, for example, can be combined or modified by individuals in conjunction with the Exercise embodiments as well as the features or elements or process steps described and contained in the drawings are inventive and lead to a new object or new process steps or process step sequences through combinable features, also insofar as they relate to manufacturing, testing and working processes.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Valve Device For Special Equipments (AREA)
- Valve-Gear Or Valve Arrangements (AREA)
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE112004002087T DE112004002087D2 (de) | 2003-11-03 | 2004-10-28 | Brennkraftmaschine |
Applications Claiming Priority (8)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
ATGM762/2003 | 2003-11-03 | ||
AT7622003 | 2003-11-03 | ||
ATA303/2004 | 2004-02-26 | ||
AT3032004A AT414011B (de) | 2004-02-26 | 2004-02-26 | Variable ventilbetätigungseinrichtung |
AT0037004A AT414010B (de) | 2004-03-04 | 2004-03-04 | Verfahren zum betreiben einer brennkraftmaschine |
ATA370/2004 | 2004-03-04 | ||
ATA412/2004 | 2004-03-09 | ||
AT4122004A AT413853B (de) | 2004-03-09 | 2004-03-09 | Ventilbetätigungseinrichtung |
Publications (2)
Publication Number | Publication Date |
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WO2005042930A2 true WO2005042930A2 (de) | 2005-05-12 |
WO2005042930A3 WO2005042930A3 (de) | 2006-05-18 |
Family
ID=34557432
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/AT2004/000372 WO2005042930A2 (de) | 2003-11-03 | 2004-10-28 | Brennkraftmaschine |
Country Status (2)
Country | Link |
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DE (1) | DE112004002087D2 (de) |
WO (1) | WO2005042930A2 (de) |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3032276A1 (de) | 1980-08-27 | 1982-03-04 | Bayerische Motoren Werke AG, 8000 München | Zylinderkopf fuer brennkraftmaschinen |
US4688527A (en) | 1986-03-31 | 1987-08-25 | Chrysler Motors Corporation | Ceramic valve guide and seat |
EP0292185B1 (de) | 1987-05-21 | 1992-06-24 | Jaguar Cars Limited | Nockenvorrichtungen |
EP1209326A2 (de) | 2000-11-22 | 2002-05-29 | BorgWarner Inc. | Variable Ventilsteuerungseinrichtung |
DE10127205A1 (de) | 2001-06-05 | 2002-09-05 | Bosch Gmbh Robert | Nockenwellenlose Steuerung eines Gaswechselventils einer Brennkraftmaschine |
DE10134644A1 (de) | 2001-07-17 | 2003-02-06 | Bosch Gmbh Robert | Elektrohydraulische Ventilsteuerung |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4850311A (en) * | 1988-12-09 | 1989-07-25 | General Motors Corporation | Three dimensional cam cardanic follower valve lifter |
DE4433742A1 (de) * | 1993-09-22 | 1995-04-20 | Aisin Seiki | Ventilsteuerungsvorrichtung |
EP0763165A1 (de) * | 1994-06-02 | 1997-03-19 | Valasopoulos, Christos | Ventilstöpsel mit variabler wirkung für hubkolbenbrennkraftmaschine |
JPH10288018A (ja) * | 1997-04-17 | 1998-10-27 | Unisia Jecs Corp | エンジンブレーキ装置 |
-
2004
- 2004-10-28 DE DE112004002087T patent/DE112004002087D2/de not_active Expired - Fee Related
- 2004-10-28 WO PCT/AT2004/000372 patent/WO2005042930A2/de active Application Filing
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3032276A1 (de) | 1980-08-27 | 1982-03-04 | Bayerische Motoren Werke AG, 8000 München | Zylinderkopf fuer brennkraftmaschinen |
US4688527A (en) | 1986-03-31 | 1987-08-25 | Chrysler Motors Corporation | Ceramic valve guide and seat |
EP0292185B1 (de) | 1987-05-21 | 1992-06-24 | Jaguar Cars Limited | Nockenvorrichtungen |
EP1209326A2 (de) | 2000-11-22 | 2002-05-29 | BorgWarner Inc. | Variable Ventilsteuerungseinrichtung |
DE10127205A1 (de) | 2001-06-05 | 2002-09-05 | Bosch Gmbh Robert | Nockenwellenlose Steuerung eines Gaswechselventils einer Brennkraftmaschine |
DE10134644A1 (de) | 2001-07-17 | 2003-02-06 | Bosch Gmbh Robert | Elektrohydraulische Ventilsteuerung |
Also Published As
Publication number | Publication date |
---|---|
WO2005042930A3 (de) | 2006-05-18 |
DE112004002087D2 (de) | 2006-09-21 |
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