US20120199085A1 - Camshaft arrangement - Google Patents
Camshaft arrangement Download PDFInfo
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- US20120199085A1 US20120199085A1 US13/500,349 US201013500349A US2012199085A1 US 20120199085 A1 US20120199085 A1 US 20120199085A1 US 201013500349 A US201013500349 A US 201013500349A US 2012199085 A1 US2012199085 A1 US 2012199085A1
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- Prior art keywords
- shaft
- rotor
- camshaft
- screw
- face
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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
- F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
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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
- F01L1/02—Valve drive
-
- 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
- F01L1/02—Valve drive
- F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
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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
- F01L1/02—Valve drive
- F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
- F01L1/047—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
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
- F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
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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
- F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
- F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
- F01L1/3442—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear using hydraulic chambers with variable volume to transmit the rotating force
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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
- F01L7/00—Rotary or oscillatory slide valve-gear or valve arrangements
- F01L7/02—Rotary or oscillatory slide valve-gear or valve arrangements with cylindrical, sleeve, or part-annularly shaped valves
-
- 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
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D13/00—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing
- F02D13/02—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation
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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
- F01L1/02—Valve drive
- F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
- F01L1/047—Camshafts
- F01L2001/0471—Assembled camshafts
- F01L2001/0473—Composite camshafts, e.g. with cams or cam sleeve being able to move relative to the inner camshaft or a cam adjusting rod
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D13/00—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing
- F02D13/02—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation
- F02D13/0203—Variable control of intake and exhaust valves
- F02D13/0215—Variable control of intake and exhaust valves changing the valve timing only
Definitions
- the invention relates to a camshaft arrangement for varying the relative angle position of at least one first cam of a camshaft relative to a second cam of the camshaft, wherein the arrangement comprises an angle adjustment device which has a stator and a rotor which is arranged so as to be rotatable relative to said stator, wherein the rotor is connected in a rotationally fixed manner to a shaft, wherein the stator is connected in a rotationally fixed manner to a hollow shaft, wherein the shaft and the hollow shaft are arranged concentrically with respect to one another, wherein the at least one first cam is connected in a rotationally fixed manner to the shaft, wherein the at least one second cam is connected in a rotationally fixed manner to the hollow shaft, and wherein the rotationally fixed connection between the rotor and the shaft is produced by means of at least one screw.
- Camshaft arrangements of said type are known as “cam in cam” systems. By means of these, it is possible for at least two cams of the camshaft—usually a number of respective cams—to be rotated relative to one another on the camshaft in order to vary the control times of the gas exchange valves of an internal combustion engine.
- camshaft systems are described for example in EP 1 945 918 B1, in GB 2 423 565 A and in WO 2009/098497 A1.
- connection constitutes, to a certain extent, a weak point. Only if the central screw is formed as an expansion screw can an adequate preload be ensured such that the connection is permanently secure. Release of the rotationally fixed connection between the shaft and rotor may nevertheless arise under intense loading. Accordingly, in generic adjusting devices, the connection of the shaft to the rotor constitutes a weak point which, in the event of failure, can lead to a malfunction of the camshaft arrangement.
- the objective addressed by the present invention is that of further developing a camshaft arrangement of the type mentioned in the introduction such that the connection between the rotor and the shaft is improved.
- a permanently secure connection it should be possible for a permanently secure connection to be ensured without having to enlarge the available installation space.
- the shaft abuts with a end face against an abutment surface of the rotor and is pulled against the abutment surface by means of the at least one screw, wherein the shaft has, along its axial extent which is situated in the region of the rotor, a cross-sectional area which increases in size up to the end face to a larger value.
- the enlargement of the cross-sectional area is preferably restricted to the region in the direct vicinity of the end face. This is to be understood to mean in particular that the enlargement of the cross-sectional area is restricted to a region which extends at most over 10 mm from the end face of the shaft; it is particularly preferably provided that the enlargement of the cross-sectional area is restricted to a region which extends between 3 mm and 8 mm from the end face of the shaft.
- the shaft may have a constant cross section along its axial extent which is situated in the region of the rotor and outside the enlargement of the cross-sectional area.
- the external diameter of the shaft at its end face preferably corresponds to at least 80% of the external diameter of a screw head of the screw, particularly preferably to at least 90% of the external diameter of the screw head.
- the transition of the external diameter of the shaft from the region of the smaller cross-sectional area to the region of the enlarged cross-sectional area is preferably continuous. It is provided in particular that the transition is of rounded design.
- a single screw which is arranged as a central screw with its axis concentric with respect to the shaft; here, the screw is advantageously designed as an expansion screw.
- the shaft may be formed, along its axial extent which is situated in the region of the rotor, as a hollow shaft and have a constant internal diameter up to the end face.
- the shaft may furthermore have, along its axial extent which is situated in the region of the rotor and up to the enlargement of its cross-sectional area, an external diameter which amounts to at most 90% of the external diameter of the shaft at its end face. It is particularly preferably provided that, up to the enlargement of the cross-sectional area of the shaft, the external diameter of said shaft amounts to between 80% and 90% of the external diameter of the shaft at its end face.
- the angle adjustment device is preferably designed as a hydraulic adjustment device.
- FIG. 1 a shows the radial section through a camshaft arrangement of an internal combustion engine, having a camshaft which is comprised of two concentric shafts, wherein the arrangement has an angle adjustment device,
- FIG. 1 b shows the detail “X” as per FIG. 1 a
- FIG. 2 schematically shows the profile with respect to time of the opening and closing of intake and exhaust valves of an internal combustion engine, as per a first possible actuation method
- FIG. 3 schematically shows the profile with respect to time of the opening and closing of the valves as per a second possible actuation method
- FIG. 4 schematically shows the profile with respect to time of the opening and closing of the valves as per a third possible actuation method
- FIG. 5 schematically shows the profile with respect to time of the opening and closing of the valves as per a fourth possible actuation method.
- FIG. 1 a and FIG. 1 b illustrate a camshaft arrangement 1 which comprises a camshaft 2 which has cams (not illustrated) which interact in a known way with gas exchange valves in order to control the gas exchange in an internal combustion engine.
- An arrangement of this type serves for varying the valve control times of an internal combustion engine. Use is usually made of hydraulically actuated adjusters.
- a first driving strategy the control of an intake valve is varied relative to an exhaust valve—or vice versa—this usually being expedient in SOHC (single overhead camshaft) or OHV (overhead valves) engine types. This permits the variation of the intake phase or of the exhaust phase using a single camshaft.
- SOHC single overhead camshaft
- OHV overhead valves
- a second driving strategy provides that the control times of one set of intake valves are changed relative to another set of valves using a single intake camshaft. This may be used if two or possibly three intake valves are provided per cylinder, and it is sought to vary the control times of one of the intake valves relative to the others on one cylinder.
- the control times of one set of exhaust valves are varied relative to another set of valves using a single exhaust camshaft. This may be used if two or possibly three exhaust valves are provided per cylinder, wherein it is sought to vary the control times of one exhaust valve relative to the others on one cylinder.
- the camshaft arrangement 1 has an angle adjustment device 3 which is connected to the camshaft 2 .
- Cams for, for example, the intake and exhaust valves of the internal combustion engine are arranged on the camshaft.
- the camshaft 2 is comprised of two coaxially arranged shaft elements, specifically of a shaft 6 and of a hollow shaft 7 in which the shaft 6 is arranged coaxially.
- the cams situated on the camshaft 2 are connected in a rotationally fixed manner either to the shaft 6 or to the hollow shaft 7 . Details regarding this are provided in EP 1 945 918 B1.
- the angle adjustment device 3 has a stator 4 and a rotor 5 which can be rotated relative to one another—in the exemplary embodiment by means of hydraulic actuation—by a defined angle.
- This realization of this relative rotation function is known in the prior art, reference being made by way of example to DE 103 44 816 A1.
- a vane wheel is provided into which vanes are formed or in which vanes are arranged.
- the vanes are situated in hydraulic chambers which are formed in a rotor.
- An adjustment of the rotor relative to the stator can be realized through corresponding charging of the respective side of the hydraulic chambers with hydraulic fluid.
- the rotor 5 is connected in a rotationally fixed manner to the shaft 6 , wherein a central screw 8 is used for this purpose.
- a secure radial and axial connection between the rotor 5 and shaft 6 is ensured by means of the central screw 8 .
- the invention provides that the shaft 6 abuts with one of its end faces 9 against an abutment surface 10 of the rotor 5 and is pulled against the abutment surface 10 by means of the central screw 8 .
- the shaft 6 has, along its axial extent which is situated in the region of the rotor 5 , a cross-sectional area A 1 which increases in size up to the end face 9 to a larger value A 2 .
- the areas A 1 and A 2 are indicated in FIG. 1 b ; in the present case these are circular ring-shaped surfaces.
- the preferred dimensioning of the face-side widening of the shaft 6 also emerges from the specified geometric data.
- the shaft 6 is formed, in the axial region of the rotor 5 , as a hollow shaft, and accordingly has an internal diameter D I .
- the external diameter of the shaft 6 is denoted by D A0 .
- the shaft 6 widens toward the end face side of the shaft 6 , that is to say the external diameter increases to a value D A .
- the axial region over which the enlargement of the cross-sectional area takes place is denoted by x.
- the external diameter D A in the end face region of the shaft 6 is preferably approximately as large as the external diameter D AS of the screw head 11 of the central screw 8 , or is slightly smaller.
- transition 12 from the smaller to the larger cross-sectional area is of rounded design, in order to eliminate stress concentrations.
- the stator 4 furthermore has a cover element 13 which is connected to the stator 4 by means of screws 14 .
- the hollow shaft 7 is connected in a rotationally fixed manner to the cover element 13 .
- the rotationally fixed connection between the stator 4 and hollow shaft 7 takes place via the cover element 13 which is connected to the stator 4 , in that the cover element 13 has a bore for receiving a cylindrical portion of the hollow shaft 7 .
- a non-positively locking and/or cohesive connection is provided in the cylindrical contact surface 15 between the cover element 13 and hollow shaft 7 .
- the angle adjustment device 3 On the side opposite the cover element 13 , the angle adjustment device 3 is closed off by means of a further cover element 16 .
- the drive of the angle adjustment device 3 , and therefore of the camshaft 2 is provided in a known way via a pinion 17 by means of a chain (not illustrated) driven by the crankshaft of the internal combustion engine.
- the pinion 17 is formed here as a separate component. It may however also be formed integrally with the stator 4 .
- connection between the rotor 5 and the shaft 6 is formed so as to be so secure that a torque adequate for effecting the actuation of the cams counter to the spring force of the gas exchange valves can be transmitted via said connection.
- FIGS. 2 to 5 The mode of operation of an internal combustion engine which is made possible by the camshaft arrangement is illustrated in FIGS. 2 to 5 .
- the Figures each show the profile with respect to time of the opening travel imparted to a valve by a cam.
- the shaft 6 actuates the exhaust valves, wherein the control of the exhaust valves can be adjusted relative to the crankshaft of the engine.
- SOHC type single overhead camshaft
- OHV overhead valve
- the actuation of the exhaust valves can be seen in the left-hand half of the Figure in FIG. 2 , whereas the right-hand half of the Figure shows the actuation of the intake valves.
- the dashed curve profiles for the exhaust valves and the offset in the direction of the double arrow indicate that the adjustment facility of the angle adjustment device 3 is utilized for this purpose.
- this permits optimized control, that is to say opening and closing, of the exhaust valves as a function of the rotational speed and of the load state of the internal combustion engine. This advantageously leads to increased fuel efficiency and reduced emissions.
- FIG. 3 shows, for the same design of engine as in FIG. 2 , the appearance of the profile if the shaft 6 actuates the intake valves. Again, the actuation of the exhaust valves is shown in the left-hand half of the Figure and that of the intake valves is shown in the right-hand half of the Figure. It is now possible here—shown again by the dashed curve profiles and the double arrow—for the phase relationship of the intake valves relative to the crankshaft to be varied.
- this permits optimized control, that is to say opening and closing, of the intake valves as a function of the rotational speed and of the load state of the internal combustion engine.
- Volumetric efficiency can be improved, which leads to improved torque delivery of the engine and increased fuel efficiency and improved running behavior of the engine.
- At least one exhaust valve (see solid line) is operated with fixed control times, whereas at least one further exhaust valve (see dashed lines and double arrow) is adjustable with regard to its control times.
- the intake valves are non-adjustable in terms of their control times (see right-hand half of the Figure).
- FIG. 5 An analogous solution to FIG. 4 is depicted in FIG. 5 .
- a DOHC type engine is used.
- the shaft 6 actuates one or more intake valves per cylinder, while the other intake valves are actuated by the hollow shaft 7 .
- control it is thereby possible in turn for control to be implemented such that the valve opening times at the intake can be varied.
- the solid lines in the right-hand half of the Figure of FIG. 5 in turn show the control of one or more intake valves with non-variable control times, whereas the dashed lines and the double arrow indicate that temporal variation of the control of the other intake valves can be realized by means of the angle adjustment device 3 .
- the duration of the opening of the intake valves can be varied.
- the closing time of the intake valves can also be optimized. This may be utilized to realize a late intake valve closing (LIVC) strategy.
- LIVC late intake valve closing
- the closing of the intake valves after bottom dead center (BDC) makes it possible for a part of the gas to be forced back into the intake tract, which reduces the length of the compression stroke. This leads to a reduction in pumping losses of the engine and thus to improved fuel efficiency.
- the closing of the intake valves can be optimized as a function of the rotational speed and engine load.
Abstract
A camshaft arrangement (1) for changing the relative angle of at least one first cam of a camshaft (2) relative to a second cam of the camshaft (2), wherein the arrangement includes an angle adjusting device (3) having a stator (4) and a rotor (5) rotatably disposed relative to said stator, wherein the rotor (5) is rotationally fixed to a shaft (6), wherein the stator (4) is rotationally fixed to a hollow shaft (7), wherein the shaft (6) and the hollow shaft (7) are disposed concentric to each other, wherein the at least one first cam is rotationally fixed to the shaft (6), wherein the at least one second cam is rotationally fixed to the hollow shaft (7), and wherein the rotationally fixed connection between the rotor (5) and the shaft (6) is produced by at least one screw (8). In order to establish a fixed connection between the rotor and the shaft, taking up little space, according to the invention, the shaft (6) having an end face (9) contacts a contact surface (10) of the rotor (5) and is pulled against the contact surface (10) by the at least one screw (8), and the shaft (6) has a cross-sectional area (A1) along the axial extent thereof present in the area of the rotor (5), with the cross-sectional area expanding to a greater value (A2) out to the end face (9) thereof.
Description
- The invention relates to a camshaft arrangement for varying the relative angle position of at least one first cam of a camshaft relative to a second cam of the camshaft, wherein the arrangement comprises an angle adjustment device which has a stator and a rotor which is arranged so as to be rotatable relative to said stator, wherein the rotor is connected in a rotationally fixed manner to a shaft, wherein the stator is connected in a rotationally fixed manner to a hollow shaft, wherein the shaft and the hollow shaft are arranged concentrically with respect to one another, wherein the at least one first cam is connected in a rotationally fixed manner to the shaft, wherein the at least one second cam is connected in a rotationally fixed manner to the hollow shaft, and wherein the rotationally fixed connection between the rotor and the shaft is produced by means of at least one screw.
- Camshaft arrangements of said type are known as “cam in cam” systems. By means of these, it is possible for at least two cams of the camshaft—usually a number of respective cams—to be rotated relative to one another on the camshaft in order to vary the control times of the gas exchange valves of an internal combustion engine. Such camshaft systems are described for example in
EP 1 945 918 B1, inGB 2 423 565 A and in WO 2009/098497 A1. - It is known to produce the rotationally fixed connection between the rotor or a part thereof and the shaft by means of a screw connection, wherein use is usually made of a central screw which is arranged concentrically with respect to the axis of the shaft and hollow shaft. The cited documents present, in part, a solution of this type.
- It has been found that this connection constitutes, to a certain extent, a weak point. Only if the central screw is formed as an expansion screw can an adequate preload be ensured such that the connection is permanently secure. Release of the rotationally fixed connection between the shaft and rotor may nevertheless arise under intense loading. Accordingly, in generic adjusting devices, the connection of the shaft to the rotor constitutes a weak point which, in the event of failure, can lead to a malfunction of the camshaft arrangement.
- The objective addressed by the present invention is that of further developing a camshaft arrangement of the type mentioned in the introduction such that the connection between the rotor and the shaft is improved. Here, it should be possible for a permanently secure connection to be ensured without having to enlarge the available installation space.
- This objective is met by means of the invention characterized in that the shaft abuts with a end face against an abutment surface of the rotor and is pulled against the abutment surface by means of the at least one screw, wherein the shaft has, along its axial extent which is situated in the region of the rotor, a cross-sectional area which increases in size up to the end face to a larger value.
- The enlargement of the cross-sectional area is preferably restricted to the region in the direct vicinity of the end face. This is to be understood to mean in particular that the enlargement of the cross-sectional area is restricted to a region which extends at most over 10 mm from the end face of the shaft; it is particularly preferably provided that the enlargement of the cross-sectional area is restricted to a region which extends between 3 mm and 8 mm from the end face of the shaft.
- The shaft may have a constant cross section along its axial extent which is situated in the region of the rotor and outside the enlargement of the cross-sectional area.
- The external diameter of the shaft at its end face preferably corresponds to at least 80% of the external diameter of a screw head of the screw, particularly preferably to at least 90% of the external diameter of the screw head.
- Here, the transition of the external diameter of the shaft from the region of the smaller cross-sectional area to the region of the enlarged cross-sectional area is preferably continuous. It is provided in particular that the transition is of rounded design.
- It is preferable for a single screw to be provided which is arranged as a central screw with its axis concentric with respect to the shaft; here, the screw is advantageously designed as an expansion screw.
- The shaft may be formed, along its axial extent which is situated in the region of the rotor, as a hollow shaft and have a constant internal diameter up to the end face. The shaft may furthermore have, along its axial extent which is situated in the region of the rotor and up to the enlargement of its cross-sectional area, an external diameter which amounts to at most 90% of the external diameter of the shaft at its end face. It is particularly preferably provided that, up to the enlargement of the cross-sectional area of the shaft, the external diameter of said shaft amounts to between 80% and 90% of the external diameter of the shaft at its end face.
- The angle adjustment device is preferably designed as a hydraulic adjustment device.
- With this embodiment, it is possible to produce a very secure connection, which takes up little space, between the rotor and shaft. As a result of the enlargement of the face-side end region of the shaft, the contact surface to the rotor is significantly enlarged, thus yielding improved and more secure abutment of the shaft against the rotor.
- The drawings show an exemplary embodiment of the invention, in which:
-
FIG. 1 a shows the radial section through a camshaft arrangement of an internal combustion engine, having a camshaft which is comprised of two concentric shafts, wherein the arrangement has an angle adjustment device, -
FIG. 1 b shows the detail “X” as perFIG. 1 a, -
FIG. 2 schematically shows the profile with respect to time of the opening and closing of intake and exhaust valves of an internal combustion engine, as per a first possible actuation method, -
FIG. 3 schematically shows the profile with respect to time of the opening and closing of the valves as per a second possible actuation method, -
FIG. 4 schematically shows the profile with respect to time of the opening and closing of the valves as per a third possible actuation method, and -
FIG. 5 schematically shows the profile with respect to time of the opening and closing of the valves as per a fourth possible actuation method. -
FIG. 1 a andFIG. 1 b illustrate acamshaft arrangement 1 which comprises acamshaft 2 which has cams (not illustrated) which interact in a known way with gas exchange valves in order to control the gas exchange in an internal combustion engine. - An arrangement of this type serves for varying the valve control times of an internal combustion engine. Use is usually made of hydraulically actuated adjusters.
- In a first driving strategy, the control of an intake valve is varied relative to an exhaust valve—or vice versa—this usually being expedient in SOHC (single overhead camshaft) or OHV (overhead valves) engine types. This permits the variation of the intake phase or of the exhaust phase using a single camshaft.
- A second driving strategy provides that the control times of one set of intake valves are changed relative to another set of valves using a single intake camshaft. This may be used if two or possibly three intake valves are provided per cylinder, and it is sought to vary the control times of one of the intake valves relative to the others on one cylinder.
- In a third driving strategy, the control times of one set of exhaust valves are varied relative to another set of valves using a single exhaust camshaft. This may be used if two or possibly three exhaust valves are provided per cylinder, wherein it is sought to vary the control times of one exhaust valve relative to the others on one cylinder.
- Here, the
camshaft arrangement 1 has anangle adjustment device 3 which is connected to thecamshaft 2. Cams for, for example, the intake and exhaust valves of the internal combustion engine are arranged on the camshaft. By means of theangle adjustment device 3, it is possible for one group of the cams to be rotated relative to another group of the cams. For this purpose, thecamshaft 2 is comprised of two coaxially arranged shaft elements, specifically of ashaft 6 and of ahollow shaft 7 in which theshaft 6 is arranged coaxially. The cams situated on thecamshaft 2 are connected in a rotationally fixed manner either to theshaft 6 or to thehollow shaft 7. Details regarding this are provided inEP 1 945 918 B1. - The
angle adjustment device 3 has astator 4 and arotor 5 which can be rotated relative to one another—in the exemplary embodiment by means of hydraulic actuation—by a defined angle. This realization of this relative rotation function is known in the prior art, reference being made by way of example to DE 103 44 816 A1. In the device described in this document, a vane wheel is provided into which vanes are formed or in which vanes are arranged. The vanes are situated in hydraulic chambers which are formed in a rotor. An adjustment of the rotor relative to the stator can be realized through corresponding charging of the respective side of the hydraulic chambers with hydraulic fluid. - The
rotor 5 is connected in a rotationally fixed manner to theshaft 6, wherein acentral screw 8 is used for this purpose. A secure radial and axial connection between therotor 5 andshaft 6 is ensured by means of thecentral screw 8. - To ensure that said connection is particularly secure, the invention provides that the
shaft 6 abuts with one of its end faces 9 against anabutment surface 10 of therotor 5 and is pulled against theabutment surface 10 by means of thecentral screw 8. To ensure improved abutment of the shaft end face against the abutment surface, it is provided that theshaft 6 has, along its axial extent which is situated in the region of therotor 5, a cross-sectional area A1 which increases in size up to the end face 9 to a larger value A2. The areas A1 and A2 are indicated inFIG. 1 b; in the present case these are circular ring-shaped surfaces. - The preferred dimensioning of the face-side widening of the
shaft 6 also emerges from the specified geometric data. Theshaft 6 is formed, in the axial region of therotor 5, as a hollow shaft, and accordingly has an internal diameter DI. The external diameter of theshaft 6 is denoted by DA0. Theshaft 6 widens toward the end face side of theshaft 6, that is to say the external diameter increases to a value DA. The axial region over which the enlargement of the cross-sectional area takes place is denoted by x. - Here, the external diameter DA in the end face region of the
shaft 6 is preferably approximately as large as the external diameter DAS of thescrew head 11 of thecentral screw 8, or is slightly smaller. - As can also be seen, the transition 12 from the smaller to the larger cross-sectional area is of rounded design, in order to eliminate stress concentrations.
- The
stator 4 furthermore has acover element 13 which is connected to thestator 4 by means ofscrews 14. Thehollow shaft 7 is connected in a rotationally fixed manner to thecover element 13. Here, the rotationally fixed connection between thestator 4 andhollow shaft 7 takes place via thecover element 13 which is connected to thestator 4, in that thecover element 13 has a bore for receiving a cylindrical portion of thehollow shaft 7. It is provided here that a non-positively locking and/or cohesive connection is provided in thecylindrical contact surface 15 between thecover element 13 andhollow shaft 7. - On the side opposite the
cover element 13, theangle adjustment device 3 is closed off by means of afurther cover element 16. The drive of theangle adjustment device 3, and therefore of thecamshaft 2, is provided in a known way via apinion 17 by means of a chain (not illustrated) driven by the crankshaft of the internal combustion engine. Thepinion 17 is formed here as a separate component. It may however also be formed integrally with thestator 4. - It is thereby possible to influence, that is to say adjust, the phase relationship between the cams connected in a rotationally fixed manner to the
hollow shaft 7 and the cams connected in a rotationally fixed manner to theshaft 6. Here, according to the invention, the connection between therotor 5 and theshaft 6 is formed so as to be so secure that a torque adequate for effecting the actuation of the cams counter to the spring force of the gas exchange valves can be transmitted via said connection. The same self-evidently applies to the connection between thestator 4 and thehollow shaft 7. - The mode of operation of an internal combustion engine which is made possible by the camshaft arrangement is illustrated in
FIGS. 2 to 5 . The Figures each show the profile with respect to time of the opening travel imparted to a valve by a cam. - In an engine with a single camshaft (SOHC type—single overhead camshaft) or an engine of OHV (overhead valve) type, the
shaft 6 actuates the exhaust valves, wherein the control of the exhaust valves can be adjusted relative to the crankshaft of the engine. Here, the actuation of the exhaust valves can be seen in the left-hand half of the Figure inFIG. 2 , whereas the right-hand half of the Figure shows the actuation of the intake valves. The dashed curve profiles for the exhaust valves and the offset in the direction of the double arrow indicate that the adjustment facility of theangle adjustment device 3 is utilized for this purpose. - In the case of
FIG. 2 , this permits optimized control, that is to say opening and closing, of the exhaust valves as a function of the rotational speed and of the load state of the internal combustion engine. This advantageously leads to increased fuel efficiency and reduced emissions. -
FIG. 3 shows, for the same design of engine as inFIG. 2 , the appearance of the profile if theshaft 6 actuates the intake valves. Again, the actuation of the exhaust valves is shown in the left-hand half of the Figure and that of the intake valves is shown in the right-hand half of the Figure. It is now possible here—shown again by the dashed curve profiles and the double arrow—for the phase relationship of the intake valves relative to the crankshaft to be varied. - In the case of
FIG. 3 , this permits optimized control, that is to say opening and closing, of the intake valves as a function of the rotational speed and of the load state of the internal combustion engine. Volumetric efficiency can be improved, which leads to improved torque delivery of the engine and increased fuel efficiency and improved running behavior of the engine. - In an engine with two overhead camshafts (DOHC type), it may be provided that the
shaft 6 with the cams fastened in a rotationally fixed manner thereto actuates one or more exhaust valves per cylinder, whereas the remaining exhaust valves are actuated by thehollow shaft 7 and the cams arranged in a rotationally fixed manner thereon. Such a solution is shown inFIG. 4 . In this case, it is possible to realize, for each cylinder, an adjustment of the actuation of one or more of the exhaust valves relative to the other exhaust valves. It can be seen in the left-hand half of the Figure inFIG. 4 that at least one exhaust valve (see solid line) is operated with fixed control times, whereas at least one further exhaust valve (see dashed lines and double arrow) is adjustable with regard to its control times. In the present case, the intake valves are non-adjustable in terms of their control times (see right-hand half of the Figure). - It is thereby possible for the duration of the opening of the exhaust valves to be varied such that the opening time of the exhaust valves can be optimized. An early opening of the exhaust valves before bottom dead center (BDC) permits a fast warm-up of the internal combustion engine, which reduces cold start emissions.
- An analogous solution to
FIG. 4 is depicted inFIG. 5 . Here, too, a DOHC type engine is used. In this case, theshaft 6 actuates one or more intake valves per cylinder, while the other intake valves are actuated by thehollow shaft 7. - It is thereby possible in turn for control to be implemented such that the valve opening times at the intake can be varied. The solid lines in the right-hand half of the Figure of
FIG. 5 in turn show the control of one or more intake valves with non-variable control times, whereas the dashed lines and the double arrow indicate that temporal variation of the control of the other intake valves can be realized by means of theangle adjustment device 3. - It is thus possible here, analogously to
FIG. 4 , for the duration of the opening of the intake valves to be varied. Furthermore, the closing time of the intake valves can also be optimized. This may be utilized to realize a late intake valve closing (LIVC) strategy. - The closing of the intake valves after bottom dead center (BDC) makes it possible for a part of the gas to be forced back into the intake tract, which reduces the length of the compression stroke. This leads to a reduction in pumping losses of the engine and thus to improved fuel efficiency. The closing of the intake valves can be optimized as a function of the rotational speed and engine load.
-
- 1 Camshaft arrangement
- 2 Camshaft
- 3 Angle adjustment device
- 4 Stator
- 5 Rotor
- 6 Shaft
- 7 Hollow shaft
- 8 Screw (central screw)
- 9 End face
- 10 Abutment surface
- 11 Screw head
- 12 Transition
- 13 Cover element
- 14 Screw
- 15 Cylindrical contact surface
- 16 Cover element
- 17 Pinion
- A1 Cross-sectional area
- A2 Cross-sectional area
- x Region (axial extent)
- DA External diameter
- DAS External diameter of the screw head
- DI Internal diameter
- DA0 External diameter
Claims (15)
1. A camshaft arrangement for varying a relative angle position of at least one first cam of a camshaft relative to a second cam of the camshaft, comprising an angle adjustment device which has a stator and a rotor which is arranged so as to be rotatable relative to said stator, the rotor is connected in a rotationally fixed manner to a shaft, the stator is connected in a rotationally fixed manner to a hollow shaft, the shaft and the hollow shaft are arranged concentrically with respect to one another, the at least one first cam is connected in a rotationally fixed manner to the shaft, the at least one second cam is connected in a rotationally fixed manner to the hollow shaft, and the rotationally fixed connection between the rotor and the shaft is produced by at least one screw, the shaft abuts with a end face against an abutment surface of the rotor and is pulled against the abutment surface by the at least one screw, the shaft has, along its axial extent which is situated in a region of the rotor, a cross-sectional area (A1) which increases in size up to the end face to a larger value (A2) creating an enlargement.
2. The camshaft arrangement as claimed in claim 1 , wherein the enlargement of the cross-sectional area (A2) is restricted to a region in a direct vicinity of the end face.
3. The camshaft arrangement as claimed in claim 2 , wherein the enlargement of the cross-sectional area (A2) is restricted to the region (x) which extends at most 10 mm from the end face of the shaft.
4. The camshaft arrangement as claimed in claim 3 , wherein the enlargement of the cross-sectional area (A2) is restricted to the region (x) which extends between 3 mm and 8 mm from the end face of the shaft.
5. The camshaft arrangement as claimed in claim 1 , wherein the shaft has a constant cross section along its axial extent which is situated in a region of the rotor that is outside the enlargement of the cross-sectional area.
6. The camshaft arrangement as claimed in claim 1 , wherein the external diameter (DA) of the shaft at the end face corresponds to at least 80% of the external diameter (DAS) of a screw head of the screw.
7. The camshaft arrangement as claimed in claim 6 , wherein the external diameter (DA) of the shaft at the end face corresponds to at least 90% of the external diameter (DAS) of the screw head of the screw.
8. The camshaft arrangement as claimed in claim 1 , wherein a transition of the external diameter of the shaft from a region of the smaller cross-sectional area (A1) to a region of the enlarged cross-sectional area (A2) is continuous.
9. The camshaft arrangement as claimed in claim 8 , wherein the transition of the external diameter of the shaft is rounded.
10. The camshaft arrangement as claimed in claim 1 , wherein the at least one screw consists of a single screw which is arranged as a central screw with an axis thereof concentric with respect to the shaft.
11. The camshaft arrangement as claimed in claim 10 , wherein the screw is an expansion screw.
12. The camshaft arrangement as claimed in claim 1 , wherein the shaft is formed, along an axial extent thereof which is situated in a region of the rotor, as a hollow shaft and has a constant internal diameter (DI) up to the end face.
13. The camshaft arrangement as claimed in claim 1 , wherein the shaft has, along an axial extent thereof which is situated in a region of the rotor and up to the enlargement of the cross-sectional area, an external diameter (DA0) which amounts to at most 90% of an external diameter (DA) of the shaft at the end face.
14. The camshaft arrangement as claimed in claim 13 , wherein, up to the enlargement of the cross-sectional area of the shaft, the external diameter (DA0) of said shaft amounts to between 80% and 90% of the external diameter (DA) of the shaft at the end face.
15. The camshaft arrangement as claimed in claim 1 , wherein the angle adjustment device comprises a hydraulic adjustment device.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US13/500,349 US20120199085A1 (en) | 2009-10-05 | 2010-10-04 | Camshaft arrangement |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US24863409P | 2009-10-05 | 2009-10-05 | |
US13/500,349 US20120199085A1 (en) | 2009-10-05 | 2010-10-04 | Camshaft arrangement |
PCT/EP2010/064752 WO2011042392A1 (en) | 2009-10-05 | 2010-10-04 | Camshaft arrangement |
Publications (1)
Publication Number | Publication Date |
---|---|
US20120199085A1 true US20120199085A1 (en) | 2012-08-09 |
Family
ID=43384513
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/500,349 Abandoned US20120199085A1 (en) | 2009-10-05 | 2010-10-04 | Camshaft arrangement |
Country Status (6)
Country | Link |
---|---|
US (1) | US20120199085A1 (en) |
EP (1) | EP2486249B1 (en) |
KR (1) | KR101675613B1 (en) |
CN (1) | CN102812214B (en) |
BR (1) | BR112012007549A2 (en) |
WO (1) | WO2011042392A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN107313821A (en) * | 2017-08-30 | 2017-11-03 | 上海汽车集团股份有限公司 | Camshaft extremity piece attachment structure |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102011052822A1 (en) | 2011-08-18 | 2013-02-21 | Thyssenkrupp Presta Teccenter Ag | Camshaft, in particular for motor vehicle engines |
CN111485969A (en) * | 2019-01-28 | 2020-08-04 | 舍弗勒技术股份两合公司 | Camshaft phase adjuster |
Family Cites Families (15)
Publication number | Priority date | Publication date | Assignee | Title |
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DE2822147C3 (en) | 1978-05-20 | 1982-02-11 | Volkswagenwerk Ag, 3180 Wolfsburg | Camshaft arrangement, in particular for an internal combustion engine |
US4771742A (en) * | 1986-02-19 | 1988-09-20 | Clemson University | Method for continuous camlobe phasing |
US5417186A (en) * | 1993-06-28 | 1995-05-23 | Clemson University | Dual-acting apparatus for variable valve timing and the like |
JPH07224617A (en) | 1994-02-09 | 1995-08-22 | Unisia Jecs Corp | Valve timing control device for internal combustion engine |
GB2369175A (en) | 2000-11-18 | 2002-05-22 | Mechadyne Plc | Variable phase coupling |
JP4126600B2 (en) | 2002-09-26 | 2008-07-30 | アイシン精機株式会社 | Control mechanism of valve timing control device |
GB2423565A (en) | 2005-02-23 | 2006-08-30 | Mechadyne Plc | Inner camshaft of SCP assembly receives drive via sleeve on outer tube |
GB2431977A (en) | 2005-11-02 | 2007-05-09 | Mechadyne Plc | Camshaft assembly |
DE102005061187A1 (en) * | 2005-12-21 | 2007-06-28 | Mahle International Gmbh | camshaft |
DE202006020695U1 (en) * | 2006-05-27 | 2009-06-25 | Mahle International Gmbh | Adjustable camshaft |
DE102007017514A1 (en) * | 2007-04-13 | 2008-10-16 | Mahle International Gmbh | camshaft |
GB2457228A (en) | 2008-02-05 | 2009-08-12 | Mechadyne Plc | Lubricating oil feed arrangement for a single cam phaser (SCP) camshaft |
DE102008019746A1 (en) * | 2008-04-19 | 2009-10-22 | Schaeffler Kg | Device for variable adjustment of valve timings of charge-cycle valves of internal combustion engine, has two drive elements and side cap, where former drive element is brought in drive connection with crankshaft |
DE102008019747A1 (en) * | 2008-04-19 | 2009-10-22 | Schaeffler Kg | Device for the variable adjustment of the timing of gas exchange valves of an internal combustion engine |
JP5552486B2 (en) | 2008-09-19 | 2014-07-16 | ボーグワーナー インコーポレーテッド | Cam torque-driven phaser using a band check valve built into camshaft or multiple concentric camshafts |
-
2010
- 2010-10-04 WO PCT/EP2010/064752 patent/WO2011042392A1/en active Application Filing
- 2010-10-04 EP EP10768214.8A patent/EP2486249B1/en not_active Revoked
- 2010-10-04 KR KR1020127008706A patent/KR101675613B1/en active IP Right Grant
- 2010-10-04 BR BR112012007549A patent/BR112012007549A2/en not_active IP Right Cessation
- 2010-10-04 US US13/500,349 patent/US20120199085A1/en not_active Abandoned
- 2010-10-04 CN CN201080044775.9A patent/CN102812214B/en active Active
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN107313821A (en) * | 2017-08-30 | 2017-11-03 | 上海汽车集团股份有限公司 | Camshaft extremity piece attachment structure |
Also Published As
Publication number | Publication date |
---|---|
CN102812214B (en) | 2015-08-05 |
EP2486249B1 (en) | 2017-04-19 |
WO2011042392A1 (en) | 2011-04-14 |
EP2486249A1 (en) | 2012-08-15 |
KR20120089281A (en) | 2012-08-09 |
KR101675613B1 (en) | 2016-11-11 |
CN102812214A (en) | 2012-12-05 |
BR112012007549A2 (en) | 2016-12-06 |
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Owner name: SCHAEFFLER TECHNOLOGIES AG & CO. KG, GERMANY Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KAPP, MATTHIAS;DUPUIS, CRAIG;CHUNG, INHWA;SIGNING DATES FROM 20120229 TO 20120301;REEL/FRAME:027995/0294 |
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STCB | Information on status: application discontinuation |
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