JP2019517635A - Electric camshaft phase shift device with a single shaft - Google Patents

Abstract

The invention relates to a control device for the continuous phase shift of the rotational angle of the camshaft 1 which controls the gas exchange valves of an internal combustion engine, and which relates to a drive element, in particular a chain or a belt. The control device comprises an electrically controlled motor 2 coupled to a reduction gear box 3 having three inputs / outputs of an external ring gear 4, input elements 6, 34 and an external disc 12, said external ring gear 4 being said drive Supported by the element, the output disc 12 is fixed to the camshaft 1. The control device comprises a single shaft 8 inside the stator 18 of the electric motor 2, which supports the input elements 6, 34 of the reduction gearbox and the rotor 16 of the electric motor 2. [Selected figure] Figure 1a

Description

  The present invention relates to the field of setting valve lift laws specific to internal combustion engines. More particularly, it relates to a camshaft incorporating a phase shift device for a variable distribution engine.

  The setting of the lift laws of the intake and exhaust valves usually requires a compromise between different goals. For example, searching for maximum performance requires a compromise between low performance torque and maximum power at high speeds. On the other hand, a compromise between idle stability, low load emissions and high speed maximum output has to be considered.

  The principle of proper setting according to speed or load is interesting.

  In addition, various systems have been applied to engines using mostly two camshafts to achieve such goals, one of the camshafts for intake and the other for exhaust. The invention relates more particularly to the field of electrical devices for controlling the rotational angle of a camshaft.

  European Patent Application Publication No. 2194241, which describes a variable cam setting device for camshafts of internal combustion engines, is known from the prior art. The device comprises a drive element, a harmonic driven reduction gearbox dynamically connected to the drive element, and an output element for camshaft drive. The reduction gearbox is controllable by means of a rotary drive shaft. In the described embodiment, this document always refers to an electric machine in which the rotor is outside the stator. The latter has to be guided via bearings on the output shaft of the reduction gearbox, which is screwed into the camshaft. Thus, the assembly of the engine is rather complicated as bearings are required between the stator and the output shaft. In addition, by using the rotor outside the stator, the main dynamic inertia makes it difficult to drive dynamically during use.

  WO 2010/068613 discloses an electrical phase shift device for a camshaft of an internal combustion engine. This device incorporates a differential gear train and is equipped with an axial flow electrical machine which enables a frictional locking. In this publication, the electric machine has no direct link connection with the shaft, and two bearings are therefore required for the positioning of the stator on the one hand and the rotor on the other hand. Thus, the ease of assembly of the engine is adversely affected.

Disadvantages of the prior art Prior art solutions are not satisfactory because they are not easy to construct and assemble and require a large number of guides.

  In addition, the prior art solutions are not completely satisfactory, especially with regard to angular accuracy. Harmonic drive gearboxes do not have high torsional stiffness. If a large torque (about 50 newtons / m) is applied by such a device, there is a risk of unintended angular shift.

  After all, assembling the reduction gear on the camshaft on the one hand and fixing the motor on the reduction gear on the other is usually seen as a competing solution, but due to the assembly provided by the Oldham coupling, the reduction gear box and the motor It is possible to determine the mechanical clearance between Such Oldham fittings add an additional part that imposes additional cost and more complicated installation.

  The object of the present invention is to provide an improved camshaft phase shift solution by using a compact motor reducer which is easy to assemble and the number of parts is minimized.

In order to eliminate the drawbacks of the prior art, the invention is most broadly for the continuous phase shift of the rotational angle of the camshaft controlling the gas exchange valve of an internal combustion engine and relates to the drive element, in particular the chain or belt. Control device.
The controller comprises a brushless electrically controlled motor having a stator fixed relative to the external ring gear, the motor being coupled with a reduction gear box having three inputs / outputs of the external ring gear, the input element and the output disc The outer ring gear is driven by the drive element and the output disc is fixed to the camshaft.
The controller includes a single shaft inside the stator of the electric motor, said electric motor being fixed to the single shaft such that the single shaft carries the rotor of the electric motor and the input elements of the reduction gearbox. Prepare.

  In a first embodiment, the reduction gearbox is a trochoidal reduction gearbox and the shaft of the single shaft carries an eccentric which allows trocoid reduction.

  Preferably, said outer ring gear has on its inner surface a tubular toothed path which engages with one or more gears mounted on said eccentric, which eccentrically distributes holes of circular cross section over the annular area of said gear And the trochoidal reduction gearbox includes a set of pins having a cross section smaller than the cross section of the hole, the pin being fixed to the output disc through the hole and the eccentrically moving gear wheel Operation transfer between the output disk and the output disk.

  In a second embodiment, the reduction gearbox is a planetary reduction gearbox and the shaft of the single shaft supports the internal sun gear.

  In this case, the inner surface of the outer ring gear preferably comprises a tubular toothed path which meshes with one or more planet gears, the planet gears moving between the planet gears and the output disc Is rotatable about a pin fixed to the output disc to ensure transmission of the

  In a particular embodiment, the single shaft has a through hole.

  The output disc is then preferably fixed to the camshaft by means of a screw with a thread which corresponds to the internal threading of the camshaft and supports the radial shoulder of the output disc.

  In a preferred embodiment, the electric motor is covered by an outer casing having a housing for receiving the single shaft guide element.

  In this case, preferably, the stator of the electric motor is overmolded and fixed to the outer casing.

  In order to control the device, the electric motor preferably comprises a circuit board supporting electronic components for control and activation of the electric coils supported by the stator.

  In order to enable control of the device, the device preferably comprises at least one position sensor which provides a signal regarding the angular position of the output disc.

  The device preferably also comprises at least one position sensor which provides a signal regarding the angular position of the external ring gear.

  If a pin is used, the pin is coupled at the free end of the pin, preferably by means of a pin holder comprising a permanent magnet located opposite to a magnetically sensitive probe forming the position sensor with the magnet.

  In order to enable installation of the device, the electric motor may comprise an outer casing having an outer surface that fits on a housing provided on a cylinder head of an internal combustion engine.

  In this case, the outer casing may also comprise a fastening element attached to the cylinder head of the internal combustion engine.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION The present invention is best understood from the following detailed description of the exemplary embodiments when read in conjunction with the accompanying drawings.

FIG. 1 shows a longitudinal section according to a first embodiment of the device according to the invention using a trochoidal reduction gearbox. FIG. 1 shows a longitudinal section according to a first embodiment of the device according to the invention using a planetary reduction gearbox. FIG. 7 is a separate illustration of an exemplary gear belonging to a trochoidal reduction gearbox that may be used in the present invention. FIG. 7 is a separate illustration of an exemplary output assembly of a trochoidal reduction gearbox that may be used with the present invention. FIG. 1 is an exploded view of an exemplary embodiment of a trochoidal reduction gearbox that may be used with the present invention. FIG. 7 is an exploded view of an exemplary embodiment of a subassembly of the present invention. Fig. 2 shows a longitudinal sectional view according to a second embodiment of the device according to the invention. FIG. 7 is an exploded view of a second embodiment of the subassembly of the present invention. FIG. 7 is an illustration of an embodiment of an output assembly that highlights the benefits of a pin holder used for phase shift measurements. FIG. 1 is an illustration of a control device according to the invention mounted on a cylinder head of a combustion engine. Fig. 3 shows a longitudinal sectional view according to a third embodiment of the device according to the invention; Fig. 4 shows a longitudinal sectional view according to a fourth embodiment of the device according to the invention;

  FIG. 1 a shows a cross-sectional view of a device according to an exemplary embodiment of the present invention coupled to a camshaft 1.

  The device consists here of an electric motor 2 in conjunction with a trochoidal reduction gearbox 3.

  The reduction gear box 3 comprises an external ring gear 4 driven by a timing chain or timing belt of an internal combustion engine (not shown). The typical outer diameter of this external ring gear 4 is 100 to 150 mm and has external teeth configured to be driven by the timing chain.

  On its inner surface there is a toothed channel 5 having a tubular shape.

  The outer ring gear 4 is free to rotate with respect to the camshaft 1.

  The eccentric gear 6 has a lower portion than the inner portion of the outer ring gear 4, and for the same module, the number of teeth of the eccentric gear 6 is the toothed path 5 on the inner surface of the outer ring gear 4. Less than the number of teeth.

  The difference between the number of teeth of the eccentric gear 6 and the number of teeth of the toothed path 5 on the inner surface of the outer ring gear 4 is preferably 1 to maximize the reduction ratio of the trochoidal reduction gearbox 3 It is one tooth.

  The eccentric gear 6 is guided by a bearing 7 mounted on an eccentric 9 on a single shaft 8, the rotational axis of the gear being shifted with respect to the central axis of the single shaft 8. The shift between the two axes usually ranges from 0.1 to 1 mm and depends on the gear module of the trochoidal mesh.

  The eccentric gear 6 has a series of circular holes 10 angularly distributed on the annular track, as can be seen in FIG.

  As shown in FIG. 3, pins 11 having a circular cross section Sg smaller than the cross section Sp of the circular holes 10 pass through these holes 10. The circular cross section Sg has a diameter reduced to half of the eccentricity between the single shaft 8 and the eccentric 9 with respect to the diameter of the cross section Sp.

  The pin 11 stands perpendicular to the cross section of the output disc 12. The output disc 12 is coaxial with the single shaft 8 and free to rotate with respect to the single shaft 8. The output disc is guided by the bearing 13 against this single shaft 8.

  In a separate embodiment, a pin holder 20 is used at the end of the pin 11. The pin holder 20 can preferably increase the stiffness against twisting of the output assembly 21 of the reduction gearbox 3 formed by the pin holder 20, the pin 11 and the output disc 12.

  The pin holder 20 may be guided on the cylindrical inner surface 27 of the outer ring gear 4, preferably in a separate embodiment. This improves the guiding of the output assembly 21 of the reduction gearbox 3.

  The output disc 12 has a shoulder 14 for guiding the outer ring gear 4.

  Furthermore, the output disc 12 is fixed to the camshaft 1 by means of a screw 23, which is connected by means of a radially enlarged portion 15 of the camshaft closest to the axis of rotation of the formed assembly.

  The invention is not limited to trochoidal reduction gearboxes. In fact, other reduction gearboxes can also be used, for example epicyclic type reduction gearboxes. A cross-sectional view using such a reduction gear box is shown in FIG. 1b in the same manner as FIG. 1a. The choice of reduction gearbox may be determined by the desired reduction ratio and the final cost of the solution.

  In the case of the planetary reduction gearbox of FIG. 1b, the single shaft 8 typically supports a sun gear 34 which meshes with two or three planets 35. The planet gears 35 also mesh with the toothed paths 5 of the external ring gear 4. The planet gear 35 is rotatable around a pin 11 fixed to the output disc 12 forming a planet gear support. The controlled relative movement between the sun gear 34 and the external ring gear 4 can control the phase shift.

  In all cases, regardless of the reduction gearbox used, the motor 2 comprises a rotor 16 fixed to a single shaft 8. Alternatingly magnetized permanent magnets 17 are typically provided radially or in a wave shape.

  In all cases, the single shaft 8 supports the input elements of the reduction gearbox as, for example, the eccentric gear 6 in the case of a trochoidal gearbox or the internal sun gear 34 in the case of a planetary gearbox.

  The stator 18 of the electric motor 2 is composed of a set of electric coils 24 forming a multiphase assembly, and usually laminated ferromagnetic parts.

  The motor 2 further includes an electronic control circuit 19 that controls the rotational operation of the motor in synchronization with the timing chain except during phase shift control.

  The assembly formed by the stator 18, the rotor 16 and the electronic circuit 19 are located in an outer casing 29, which is a housing or an overmolded skin. The single shaft 8 is thus guided relative to the outer casing 29 by means of the bearing 30 between the reduction gearbox and the rotor 16.

  A seal 22, typically a lip seal, contacts the outer casing 29 of the motor to ensure sealing of the motor and in particular to prevent oil from rising towards the stator 18 and the electronic circuit 19. It is disposed on the shaft 8.

  The mounting of the motor decelerator thus formed is greatly simplified in this embodiment. In fact, the rotor 16 and the output disc 12 and all the reduction gearbox elements 3 can be mounted on a single shaft 8. Then, after arranging the seal 22 to enable attachment of the assembly to the camshaft 1 via the radially enlarged portion 15 having a diameter smaller than the hollow inner diameter of the single shaft 8, the electric motor 2 can be It can be attached to one shaft 8. Thereafter, the radially enlarged portion 15 of the camshaft 1 can be screwed together to mount the single shaft 8 coaxially with the camshaft 1.

  An important advantage of this solution is, therefore, to provide a generally hollow single shaft 8 and that the reduction gearbox 3 can be easily screwed in after assembly placement.

  FIG. 5 shows the subassembly and its assembly procedure.

  According to another solution of FIG. 6 showing a specific embodiment, the single input shaft 8 of the reduction gearbox supporting the magnets of the electric motor 2 is fully guided and supported by the reduction gearbox 3 Ru. This embodiment allows for positioning. Firstly, the reduction gearbox 3 with a single shaft 8 makes it possible to support the rotor 16 directly on the camshaft 1 and then, secondly, the stator of the electric motor 2 on said input shaft 8 It is possible to insert 18 directly. Thus, assembly is easy and can be significantly simplified. The clearance between the magnet 17 of the electric motor 2 and the stator 18 for this particular embodiment is preferably in the cylindrical housing of the magnet of the electric motor 2 in the single input shaft 8 of the reduction gearbox 3 and the stator 18 It must be increased to allow for possible misplacement between the axes. Here, the use of a brushless motor, ie a motor without any mechanical contact between the stator and the rotor, is a particular advantage in this respect. It should also be noted that a single shaft 8 can be used as a ferromagnetic yoke for the magnet 17, as shown in FIG.

  FIG. 7 makes it possible to easily install by initially arranging the reduction gearbox 3 having a single shaft 8 on the camshaft 1. The stator 18 of the electric motor 2 is then screwed further into the cylinder head 26 of the engine in the housing 25 by means of the binding elements 33 here in the form of eyelets, in order to form the assembly shown in FIG. Make it possible.

  It should be noted that in this embodiment the presence of a completely hollow single shaft 8 is not necessary. This is because a single shaft must be attached prior to the positioning of the stator 18. Thus, as shown in FIG. 10, after the reduction gear box 3 is mounted on the camshaft 1, the sealing made by the reverse lip seal 22 and the closing of the assembly by the stator in its casing 29 Positioning of the rotor 16 mounted on one shaft 8 is possible. The electric motor 2 is then attached with its fastening element 33 by its casing 29 on the cylinder head. Also in this embodiment, the lip seal may be removed if the sealing is provided by a casing that entirely covers the engine and their electronic components. This alternative solution is shown in FIG.

  By using the reduction gear box 3 shown in the various embodiments and defined according to the invention, preferably it is possible to integrate the position sensor. As shown in FIG. 3, a pin holder 20 sliding on the cylindrical inner surface 27 of the outer ring gear 4 is connected to the output disc 12 to form an output assembly 21. The positioning of a sensor magnet, for example in the form of a disk or magnet ring 31, fixed to this output assembly is also conceivable. The positioning of the probe for measuring the magnetic field beside the stator 18 opposite the magnet ring or disc 31 makes it possible to construct a phase shift absolute position sensor. That is, it becomes possible to know the position of the camshaft 1. If the position sensor is connected to the external ring gear 4 or to the shaft of the internal combustion engine, a phase shift is known.

  From the description of the invention that has been made, it is clear that the invention is not limited to the type of electric motor used. In fact, various reluctance motors can be considered instead of motors with magnetized rotors.

Claims (15)

A control device for the continuous phase shift of the rotational angle of the camshaft (1) which controls the gas exchange valve of an internal combustion engine, and associated with a drive element, in particular a chain or a belt,
The control device comprises a brushless electrically controlled motor (2) having a stator (18) fixed relative to the external ring gear,
The motor is coupled to a reduction gearbox (3) having three inputs / outputs, said external ring gear (4), input elements (6, 34) and output disc (12),
The external ring gear (4) is driven by the drive element,
The output disc (12) is fixed to the camshaft (1),
The controller comprises a single shaft (8) inside the stator (18) of the electric motor (2),
The electric motor is fixed to the single shaft (8) such that the single shaft (8) supports the rotor of the electric motor (2) and the input element (6, 34) of the reduction gearbox. A control device comprising the rotor (16).   The transmission according to claim 1, characterized in that the reduction gearbox (3) is a trochoidal reduction gearbox and the shaft of the single shaft (8) carries an eccentric which allows for trocoid reduction. Control device for continuous phase shift of the rotational angle of the camshaft (1) described.   The outer ring gear (4) has on its inner surface a tubular toothed path (5) which meshes with one or more gears (6) attached to the eccentric, the eccentric being the one of the gear (6) A hole (10) of circular cross section is distributed over the annular area, said trochoid reduction gearbox (3) comprising a set of pins (11) having a cross section smaller than the cross section of said hole (10); (11) is fixed to the output disc (12) so as to penetrate the hole (10), and guarantees the transfer of movement between the eccentrically moving gear (6) and the output disc (12) Control device for continuous phase shift of the rotation angle of the camshaft (1) according to claim 2, characterized in that   Camshaft according to claim 1, characterized in that the reduction gearbox (3) is a planetary reduction gearbox and the shaft of the single shaft (8) supports an internal sun gear (34). Controller for continuous phase shift of the rotation angle of (1).   The inner surface of the outer ring gear (4) has a tubular toothed path (5) that meshes with one or more planet gears (35), the planet gears comprising the planet gear (35) and the output A cam according to claim 4, characterized in that it is rotatable about a pin (11) fixed to said output disc (12) to ensure transmission of movement between the disc (12). Controller for continuous phase shift of the rotation angle of the shaft (1).   A control device for continuous phase shift of the rotational angle of a camshaft (1) according to claim 1, characterized in that the single shaft (8) has a through hole.   Said output disc (12) is matched by the internal thread of said camshaft (1) and by means of a screw (23) with threads supporting the radial shoulder (15) of said output disc (12) 7. Control device for the continuous phase shift of the rotational angle of a camshaft (1) according to claim 6, characterized in that it is fixed to the camshaft (1).   The camshaft according to claim 1, characterized in that the electric motor (2) is covered by an outer casing (29) having a housing for receiving the guide element (30) of the single shaft (8). Controller for continuous phase shift of the rotation angle of (1).   9. A continuous rotation angle of a camshaft (1) according to claim 8, characterized in that the stator (18) of the electric motor (2) is overmolded and fixed to the outer casing (29). Controller for dynamic phase shift.   The electric motor (2) comprises a circuit board (19) supporting electronic components for control and activation of an electric coil (24) supported by the stator (18). Control device for continuous phase shift of the rotational angle of the camshaft (1) described.   A control for the continuous phase shift of the rotational angle of a camshaft (1) according to claim 1, characterized in that it comprises at least one position sensor which supplies a signal regarding the angular position of the output disc (12). apparatus.   The camshaft (1) for the continuous phase shift of the rotation angle of a camshaft (1) according to claim 1, characterized in that it comprises at least one position sensor which supplies a signal regarding the angular position of the external ring gear (4). Control device.   The pin (11) is characterized in that it is coupled at the free end of the pin by a pin holder (20) comprising a permanent magnet located opposite to a magnetically sensitive probe forming the position sensor with the magnet. The control device for continuous phase shift of the rotation angle of the camshaft (1) according to claim 3, 3 or 12 or 5.   A cam according to claim 1, characterized in that the electric motor (2) comprises an outer casing (29) having an outer surface which fits on a housing provided on a cylinder head (26) of the internal combustion engine. Controller for continuous phase shift of the rotation angle of the shaft (1). The continuous rotation angle of camshaft (1) according to claim 14, characterized in that said outer casing (29) comprises a fastening element (33) attached to said cylinder head (26) of said internal combustion engine. Controller for flexible phase shift.

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