Patent Application
20150083061
This application claims priority to foreign German patent application No. DE 102013015844.3, filed on Sep. 24, 2013, the disclosure of which is incorporated by reference in its entirety.
The present invention relates to a cam phaser transmission device adjustable in the angle of rotation with a drive gear and an output gear, where the drive gear and the output gear are arranged coaxial relative to the axis of rotation of the transmission device, and with a transmitter element revolving eccentrically about the axis of rotation and an actuating device, where the actuating device comprises an eccentric portion acting upon the transmitter element.
Conventional planetary gear mechanisms are used in the art as single or multi-stage gears for very different applications. In this, the planetary gear mechanisms can be designed as a toothed gear mechanism or a friction gear mechanism and can, in addition to axes fixed to the frame not changing their position in the gear housing, also comprise revolving axes revolving in circular orbits in the gear mechanism. In addition to the transmission of a rotational motion, addition and distribution gears are with a planetary gear mechanism easily realized. Since planetary gear mechanisms always have at least two shafts fixed to the frame and one revolving shaft, at least one two-stage gear transmission is always given with an overall relatively high transmission ratio in contrast to simple single-stage stationary gear mechanisms. With arranging an outer ring gear and an inner sun gear in one plane, a particularly short planetary gear mechanism can be realized.
The possibility of a planetary gear mechanism in a three-shaft operation using two shafts for driving the gear mechanism and always using one shaft for the output enables a large range of different applications, for example, for driving hybrid vehicles. Transmission devices adjustable in the angle of rotation that are used as cam phasers for increasing performance and fuel economy in modern internal combustion engines are usually designed as single-stage or multi-stage planetary gear mechanisms. In this, a second drive shaft controls adjustment of the angle of rotation between the first drive shaft and the output shaft.
Cam phasers provide adjustment of valve opening times to the load behavior of the engine during operation of internal combustion engines. The adjustment of overlap times of the exhaust valves and intake valves allows not only for fuel savings as well as power and torque gains but also for reduction in emissions, which is important in view of the ever-increasing requirement to comply with emission standards.
In addition to planetary gear mechanisms, a whole number of different designs and concepts for transmission devices that are adjustable in the angle of rotation are used as cam phasers. Most widely spread are nowadays hydraulic cam phasers that are based on a swing motor known from hydraulic technology and equipped with several vanes to increase the transmittable torque. Hydraulic cam phasers are in the internal combustion engine driven via the engine oil circuit, which is why operation of the cam phaser depends on the pressure and the temperature of the engine oil, and therefore on the operating temperature and the rotational speed of the internal combustion engine.
In addition, electric cam phasers are known that operate independently of oil pressure. Due to the electric actuation of the cam phaser, they can also be adjusted in an internal combustion engine that is not operational and additional hydraulic pumps can be avoided in the engine oil circuit. DE 41 10 195 A1 describes an electric cam phaser in which an electric motor effects relative adjustment of the angle of rotation of the camshaft relative to the camshaft gear. Either a threaded portion with a spline or a planetary gear with a self-locking transmission ratio is used as an actuating mechanism. EP 573 019 B1 further describes a parallel planetary gear mechanism with internally toothed gear wheels in which several eccentric elements driven by a shaft eccentrically rotate a plurality of gear wheels with external toothing and in sections make them engage with the internal toothing of the ring gears.
The cam phaser or transmission devices adjustable in the angle of rotation known in prior art entail various problems depending on the design and embodiment. Whereas hydraulic swing motors are in a negative manner dependent upon the pressure and temperature of the engine oil, the respective cam phasers with electric actuation have drawbacks in terms of actuating speed, the required actuating energy, self-locking or of running smoothly, in particular, when being embodied as eccentric gear mechanisms.
Although the designs and concepts for cam phasing known in the art have overall proven themselves for the use in modern internal combustion engines, there are continuous efforts to realize optimized designs, especially with regard to the large quantities common in the automotive industry, and to eliminate or minimize existing problems. In view of the ongoing innovative activity to increase efficiency of internal combustion engines, there is furthermore generally the necessity to describe new solutions to replace employed designs with optimized or inexpensive concepts.
The present invention is therefore based on the object to provide a cam phaser transmission device adjustable in the angle of rotation to improve problems of transmission devices known in prior art with relative adjustment of two drive components and to enable high positioning accuracy and operational reliability at the lowest possible production effort.
This object is solved in that the transmitter element is formed as a lantern element, where the lantern element comprises a transmitter disk being disposed eccentric to the axis of rotation and having a plurality of pins that protrude concentric to the transmitter disk on a first face side of the transmitter disk, where the lantern element partly engages with the drive gear and partly engages with the output gear, and where the lantern element is by the eccentric portion movable via the transmitter disk eccentrically about the axis of rotation in order to move the drive gear and the output gear relative to each other. With the use of lantern elements that on the side of the drive and output gears engage with suitable positive-fit elements, for example, lantern gears, gear wheels or corrugated bands, the use of precision-ground or braced gears can in transmission devices or gear mechanisms adjustable in the angle of rotation be dispensed with, whereby a major cost factor in the manufacture of power-split gear mechanisms can be saved. In this, suitable lantern elements are generally composed of at least one disk on which a plurality of pins are provided with regular spacing concentric to the center of the disk and are welded or riveted into associated bores on the disk or otherwise attached and protrude perpendicular relative to the respective face side, i.e. in an axially parallel manner to the disk axis. In the redirection of forces of the lantern element onto the drive gear and the output gear, the pins are essentially subjected to shear stress, so that the wear of the toothing of gear components otherwise occurring can be reduced.
In conventional use, lantern elements are used for slow drive elements in high-contamination environments, such as in mining, where high contamination must not lead to malfunction of a drive. In addition to the limitation to relatively only low drive speeds, lantern elements can there also transmit only relatively small forces, as the associated lantern gears are in conventional applications strongly rounded at the base circle and the base of the tooth is thereby weakened. In contrast to the conventional application of lantern elements, the transmission device according to the invention uses lantern elements for both high speeds as well as for relatively high forces.
While transmission devices adjustable in the angle of rotation common today are in the range of high transmission ratios, in particular as cam phasers in internal combustion engines, primarily implemented by using multi-stage planetary gears of which the power take-off is provided with a corresponding high-revving motor, the solution according to the invention enables a single or multiple stage transmission device which due to the integrative co-action of three rotating components and an actuating device enables a direct very high reduction ratio despite requiring a small installation space. This design according to the invention is not a mere compilation of partially optimized components, but rather an integral, customized, complex design of an intelligent system for power transmission.
The key element of this transmission device adjustable in the angle of rotation according to the invention is there the transmitter element formed as a lantern element which in sections engages with the drive gear and in sections with the output gear and is positioned eccentric relative to the axis of rotation. The lantern element, due to its special design as an embedded rigid non-elastic wobble body, there enables a power increase when engaged with the drive gear and the output gear in a kind of wedge effect. Due to the eccentric arrangement of the circular transmitter disk, a flat cylindrical disk with a concentric recess, the radius of which is by a multiple larger than its thickness and the main axis of which is offset in an axially parallel manner relative to the axis of rotation of the transmission device, a wobbling motion of the transmitter disk occurs during actuation of the transmitter element by the eccentric portion of the actuating device together with a change in the axis position of the disk which rotates with the eccentricity c about the axis of rotation.
While the wobbling transmitter disk and the pins protruding relative to a first face side perform a radial motion relative to the axis of rotation, a tangentially acting force results at the drive gear and the output gear leading to a relative motion. The design of the drive gear, the output gear and the transmitter element is there coordinated such that the circular transmitter disk performs an off-center wobbling circular motion with the eccentricity ε relative to the axis of rotation. With the design according to the invention on the basis of an eccentrically rotating, wobbling lantern element, large reduction ratios can be achieved depending on the design and arrangement of the elements. In the main use case of application of transmission devices adjustable in the angle of rotation, the use as a cam phaser, a respective high reduction enables the use of small-sized actuators and low backlash to the actuator by the self-locking of the high transmission ratio.
A preferred embodiment provides that the transmitter disk also comprises a plurality of pins on the second face side which are arranged concentric and protrude relative to the second face side. In contrast to a one-sided engagement of the drive or output gear on the inner and outer side of the ring of pins, the ring-shaped arrangement of pins on both face sides of the transmitter disk enables independent engagement of the drive and the output gear with freely selectable transmission ratios. It is there advantageous if the pins protruding concentrically relative to the first face side and the pins protruding concentrically relative to the second face side of the transmitter disk are arranged on different radii of the transmitter disk. The different radii of the concentrically disposed rings of pins, i.e. the different distance between the center of the transmitter disk and the circular line of the pins disposed in a ring-shaped manner increases the freedom of design for drive and output gears being in engagement with this lantern element. For different transmission ratios, the number of pins protruding concentrically relative to the first face side and the number of pins protruding concentrically relative to the second face side can there differ. The different number of pins equally spaced at the circumference on a circular line enables different transmission ratios irrespective of the design of the drive gear and the output gear. The pins protruding concentrically relative to the first and respectively second face side of the transmitter disk wobble together with the transmitter disk relative to the axis of rotation of the transmission device, so that they engage only in sections with the drive gear and the output gear.
An advantageous embodiment provides that the number of pins protruding concentrically relative to the first face side and/or the number of pins protruding concentrically relative to the second face side is as large as possible, for example, is greater than 50. With a large number of pins protruding relative to a planar side, high transmission ratios can be achieved already with a single-stage transmission device, i.e. a high reduction of the power take-off via the actuating device. The number of positive-fit elements on the drive gear and on the output gear preferably differs by 2, in particular by 1, from the number of protruding pins, i.e. is only slightly greater than or less than the number of pins.
The drive gear and the output gear can advantageously comprise lantern gears that engage in sections with the lantern element. Unlike milled or ground gears that require high-precision manufacturing in particular for planetary gear mechanisms, lantern gears can be produced by simple punching. To realize the thinnest possible transmission device, the drive gear and the output gear can there externally toothed lantern gears that use the inner ring space of the one ring of pins protruding from at least one face side of the transmitter disk, where the drive gear and the output gear each engage in sections on one face side with the protruding pins. Alternatively, the drive gear and the output gear can be configured as ring gears and with an internal toothing engaging from the outside with the lantern element. The teeth of the lantern gear can in an advantageous modification be designed as being flat in order to avoid weakening the base of the tooth. Such flat teeth, receiving only about half or slightly more than half of the pins, allow high speeds during engagement of the lantern elements with the lantern gears.
A special design of the transmission device adjustable in the angle of rotation provides that the transmission device is designed as a two-stage gear, the two-stage gear comprises a first and a second lantern element disposed eccentric relative to the axis of rotation and a transition element which in sections engages with the first lantern element and in sections with the second lantern element, where the drive gear in sections engages with the first lantern element and the output gear in sections engages with the second lantern element. The configuration of the transmission device as a two-stage gear allows a very high reduction ratio and very good self-locking. Depending on the manner in which the drive gear and the output gear engage with the first and the second lantern element, the configuration as a two-stage gear allows for a change of the sign of the transmission, so that there can be a subtraction of transmission rations slightly differing from each other, whereby extremely large transmission rations can be realized.
In an inverted configuration of the invention, the drive gear and the output gear are formed as lantern elements having a plurality of pins arranged concentric relative to the axis of rotation, and the transmitter element is formed as a lantern gear, where the lantern gear comprises a transmitter disk disposed eccentric relative to the axis of rotation with a first and a second lantern toothing which are arranged concentric to the transmitter disk, where the lantern elements of the drive gear and the output gear each in sections engage with the first and the second lantern toothing of the transmitter disk and where the transmitter disk is eccentrically movable about the axis of rotation by the eccentric portion in order to move the drive gear and the output gear relative to each other The transmitter element can there comprises two lantern gears of different circumference connected to each other in a rotationally-fixed manner eccentric to the axis of rotation which by the eccentric portion of the actuating device engage with the pins, being arranged concentric relative to the axis of rotation, of the lantern elements of the drive gear and the output gear. The basic mode of operation of this inverted configuration of a transmission device adjustable in the angle of rotation does not differ from the embodiment described above having an eccentrically revolving lantern element, for which reason reference is respectively presently made to the advantages of the invention already described above.
A main embodiment provides that the actuating device comprises a power take-off shaft on which auxiliary shaft the eccentric portion is arranged and which is coupled to an actuating drive, preferably to an electric motor. Such a power take-off shaft not only enables simple coupling of an actuator and thereby a simple drive but also simple formation of the circular eccentric portion. For an advantageous configuration, bearing seats can be provided on the power take-off shaft on which the drive gear and the output gear are mounted. This eliminates the need for any further mounting of the transmission device and a counter bearing by the output shaft associated with the output gear, for the cam phaser, the associated camshaft.
For operating the adjustment of the angle of rotation as smooth as possible via the actuating device, a bearing seat can be provided on the eccentric portion on which the eccentrically revolving transmitter disk is mounted. In addition to simple ball bearings, roller bearings or sliding bearings can also be provided between the transmitter disk wobbling about the axis of rotation and the circular eccentric portion disposed eccentric relative to the axis of rotation.
The present invention also relates to a cam phaser for an internal combustion engine with a transmission device adjustable in the angle of rotation, where the drive gear is by a timing assembly (timing chain) coupled at a fixed angle of rotation to the crankshaft and the output gear to a camshaft. Such a cam phaser, despite the use of simple components, enables reliable adjustment of the angle of rotation of the camshaft relative to the camshaft gear of an internal combustion engine with a large reduction ratio and good self-locking.
An embodiment of the transmission device adjustable in the angle of rotation shall below be explained with reference to drawings. In the drawings:
The sectional view in
A plurality of pins is provided respectively on the first face side 14 and the second face side 15 of the transmitter disk 13 and arranged concentric to the eccentric axis E with equal spacing on a circular path. The pins 16 extend through respective bores 17 on the transmitter disk 13 in which the pins are fixedly anchored using known joining methods of chain technology, for example rivets. The fixed joining of the pins 16 in the bores 17 of the transmitter disk 13 enables the production of a stable and highly accurate lantern element 20, i.e. the revolving transmitter element can in the transmission device 1 according to the invention adjustable in the angle of rotation also be used during higher speeds and higher transmission of forces. Alternatively, the pins 16 can also be disposed in the circumferential surface of the transmitter disk 13 and protrude relative to a face side 14, 15.
The drive gear 3 is on the side facing the transmitter disk 13 provided with a lantern gear 18 which is arranged in the inner space formed by the pins 16 protruding form the first face side 14 of the transmitter disk 13 and in sections engages with the pins 16 protruding at the first face side 14. Also on the side of the output gear 4 facing the transmitter disk 13, a lantern gear 19 is provided which is arranged in the inner space formed by the pins 16 protruding on the second face side 15 of the transmitter disk 13 and in sections engages with the pins 16 protruding on the second face side 15.
Due to the eccentricity e of the transmitter disk 13 relative to the axis of rotation D, the pins 16 protruding on the first face side 14 and the second face side 15 each only in sections completely engage with the lantern gears 18 and 19, respectively, of the drive gear 3 and the output gear 4, which can be seen in
The double ball bearing 9 positioned on the drive bearing seat 7 is in the side view of the transmission device 1 in
The perspective side view in
In an alternative inverted embodiment, the drive gear 3 and the output gear 4 are configured as lantern elements 20 comprising a plurality of pins 16 arranged concentric relative to the axis of rotation D, where the transmitter disk 13 arranged eccentric relative to the axis of rotation D comprises a first and a second lantern toothing being arranged concentric to the transmitter disk 13. The lantern elements 20 of the drive gear 3 and the output gear 4 each in sections engage with the first and the second lantern toothing of the transmitter disk 13 in order to move the drive gear 3 and the output gear 4 relative to each other. The transmitter element 5 can there comprise two lantern gears of different circumference connected to each other in a rotationally-fixed manner eccentric to the axis of rotation D which by the eccentric portion 10 of the actuating device 6 engage with the pins 16, being arranged concentric to the axis of rotation D, of the lantern elements 20 of the drive gear 3 and the output gear 4. The basic mode of operation of this inverted configuration of a transmission device adjustable in the angle of rotation does not differ from the transmission device 1 illustrated in
The function and the mode of operation of a transmission device 1 adjustable in the angle of rotation, or respectively a cam phaser 24, are illustrated in detail below.
For transmission of a rotational motion of a main drive, for example the motion of a crankshaft (not shown) of an internal combustion engine, the camshaft gear wheel 26 and the drive gear 3 fixedly connected thereto is during operation by use of the transmission device 1 via the lantern element 20 in sections being in engagement with the drive gear 3 and the output gear 4 coupled to the output gear 4 and from there connected to the camshaft 25.
As clearly visible in
For adjustment of the angle of rotation between the drive gear 3 and the output gear 4, when used as a cam phaser 24, respectively the adjustment of the angle of rotation between the camshaft gear wheel 26 attached between the drive gear 3 and the camshaft 25 arranged on the output gear 4, an additional rotational motion is via the power take-off shaft 2 forced upon the lantern element 20 by the eccentric portion 10. For this purpose, a suitable drive is attached to the power take-off shaft 2, commonly a traveling electric motor 28.
The transmitter disk 13 of the lantern element 20 mounted eccentric relative to the gear axis D on a ball bearing 12 is via the rotational motion of the circular eccentric portion 10 being eccentric relative to the axis of rotation D of the power take-off shaft 2 also activated to perform a wobbling motion about the gear axis of rotation D.
The ball bearing 12 positioned between the eccentric portion 10 and the transmitter disk 13 on the eccentric bearing seat 11 there allows a low-friction relative motion between the lantern element 20 and the eccentric portion 10. The eccentrically arranged region of the circular eccentric portion 10 via the ball bearing 12 presses the transmitter disk 13 or the pins 16 protruding at the first and the second face side 14, 15, respectively, into the toothing of the lantern gears 18, 19 of the drive gear 3 and the output gear 4, so that, with a revolution of the eccentric portion 10, the lantern element 20 rolls over the entire circumference on the lantern gears 18 and 19. In this, the drive gear 3 and the output gear 4 move relative to the lantern element 20 each offset by the difference between the number of pins 16 on the first and the second face side 14, 15 of the transmitter disk 13 and the number of the tooth gaps of the associated lantern gears 18, 19. While on the one side, see Fig. below 1, the pins 16 protruding from the first and the second face side 14, 15 are in engagement with the associated lantern gears 18, 19 of the drive gear 3 or the output gear 4, respectively, a gap S amounting to approximately twice the eccentricity e arises between the pin 16 and the Lantern gears 18, 19 on the opposite side of the transmitter disk 13 being spaced by the eccentricity e from the axis of rotation D. Gap S prevents overlap of the pins 16 with the protruding teeth of the lantern gears 18, 19, thereby allowing eccentric revolution of the lantern element 20 between the drive gear 3 and the output gear 4.
When adjusting the angle of rotation between the drive gear 3 and the output gear 4 of the transmission device 1, respectively adjustment of the angle of rotation between the camshaft gear wheel 26 and the camshaft 25 of the cam phaser 24, the co-rotating rotor of the electric motor 28, in the event of use of a co-rotating electric motor 28, arranged on the power take-off shaft 2 is accelerated or decelerated so that the position of the eccentric portion 10 and thereby of the transmitter disk 13 changes relative to the drive gear 3 and the output gear 4. During mere transmission of the main drive to the drive gear 3, i.e. during mere transmission of the rotational motion of the crankshaft-fixed camshaft gear wheel 26 to the camshaft 25 on the other hand, the relative position of the drive gear 3 and the output gear 4 relative to each other does not change.
When adjusting the angle between of rotation between the drive gear 3 and the output gear 4 of the transmission device 1, respectively adjustment of the angle of rotation between the camshaft gear wheel 26 and the camshaft 25 of the cam phaser 24, the co-rotating rotor of the electric motor 28, in the event of use of a co-rotating electric motor 28, arranged on the power take-off shaft 2 is accelerated or decelerated so that the position of the eccentric portion 10 and thereby of the transmitter disk 13 changes relative to the drive gear 3 and the output gear 4. During mere transmission of the main drive to the drive gear 3, i.e. during the mere transmission of the rotational motion of the crankshaft-fixed camshaft gear wheel 26 to the camshaft 25 on the other hand, the relative position of the drive gear 3 and the output gear 4 relative to each other does not change. During a motion of the transmitter disk 13, the pins 16 of the lantern element 20 roll around the lantern gears 18, 19, whereby the drive gear 3 and the output gear 4 move relative to each other. The reduction ratio of the lantern element 20 from the lantern gear 18 of the drive gear 3 to the lantern gear 19 of the output gear 4 results from the different rolling distance of the lantern element 20 on the lantern gear 18 as compared to the lantern gear 19.
The transmission device 1 according to the invention shown in the embodiments in
D: axis of rotation
| Number | Date | Country | Kind |
|---|---|---|---|
| 1020130158443. | Sep 2013 | DE | national |
