Patent Publication Number: US-11047269-B2

Title: Valve train device

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     The invention relates to a valve train device and to a method for operating a valve train device. 
     A valve train device is already known from DE 10 2015 014 175, in particular for an internal combustion engine, comprising a support element secured to the housing and comprising at least one axially shiftable cam unit that is associated with a valve and comprising at least one switch unit for axially shifting at least part of the cam unit, which comprises at least one displacement body, which is provided so as to displace at least part of the cam unit for axial shifting. 
     The object of the invention in particular is to provide a valve train device having an advantageously variable means for switching a cam unit using a displacement principle. 
     The invention proceeds from a valve train device, in particular for an internal combustion engine, comprising a support element secured to the housing and comprising at least one axially shiftable cam unit that is associated with a valve and comprising at least one switch unit for axially shifting at least part of the cam unit, which comprises at least one displacement body, which is provided so as to be introduced for axially shifting at least operatively between the support element and the cam unit. 
     It is proposed that the cam unit has at least three cam tracks. As a result, it can be particularly advantageous to provide a valve train device which can be switched using a displacement principle and which is of a particularly variable design. A “support element secured to the housing” is to be understood in particular to mean an element, for example bearing points for a camshaft, which is securely connected to a housing of the valve train device. In principle, it is also conceivable that the support element secured to the housing is designed to be part of the housing of the valve train device. A “cam unit” is to be understood in particular to mean a unit of at least one cam element, in which a cam element is arranged non-rotatably and preferably so as to axially shift on a camshaft and is provided, in order to actuate a valve, to subject the corresponding valve directly or indirectly to at least one valve lift. For this purpose, a cam element has at least one cam track, preferably a plurality of cam tracks. A cam unit for actuating a valve preferably has a cam element comprising a plurality of, preferably in particular three, different cam tracks. Particularly advantageously, a cam unit for actuating two valves of a cylinder has a cam element, in each case having a plurality of cam tracks arranged in groups for actuating each of the valves. In principle, it is also conceivable that a cam unit for actuating a valve has a plurality, preferably at least three, cam elements each having a cam track for actuating the valve. A “camshaft” is to be understood in particular to mean a shaft which is provided for actuating a plurality of valves of the internal combustion engine and in each case has at least one cam track for actuating a valve. It is also conceivable that the camshaft is designed as an intake camshaft and is provided to actuate intake valves, and that the camshaft is designed as an exhaust camshaft and is provided to actuate exhaust valves. In principle, it would also be conceivable that the camshaft is provided for actuating intake valves and for actuating exhaust valves. A “cam track” is to be understood in particular to mean a region that extends around a circumference of the camshaft, preferably around a circumference of a cam element, which region forms a valve actuation curve for valve actuation and/or which defines the valve actuation. A “switch unit” is to be understood in particular to mean a unit which is provided to shift at least part of a cam unit, preferably the entire cam unit, axially on the camshaft in order to bring different cam tracks of the cam element into engagement with the corresponding valve. The switch unit preferably has an actuator and a coupling element connected to the actuator and to the cam element to be adjusted. The coupling element is preferably designed as a displacement body. An “actuator” is to be understood in particular to mean a mechatronic component which is provided to convert electrical and/or electronic signals into a movement, in particular into a rotary and/or linear movement. In this case, an actuator is preferably designed as a spindle drive, a pneumatic piston, a hydraulic piston or as another actuator that a person skilled in the art deems appropriate. As a result, the switch unit is provided in particular to axially shift the cam unit. In this case, the switch unit is preferably controlled by a control and/or regulating unit. In particular, “provided” is understood to mean specifically designed, equipped and/or arranged. A “control and/or regulating unit” is to be understood in particular to mean a unit having at least one electronic controller. An electronic “controller” is to be understood in particular as meaning a unit having a processor unit and a memory unit and having an operating program stored in the memory unit. In principle, the control and/or regulating unit may have a plurality of interconnected controllers, which are preferably provided so as to communicate with one another via a bus system, in particular a CAN bus system. Depending on further design, the control and/or regulating unit may also have hydraulic and/or pneumatic components, in particular valves. 
     A “displacement body” is to be understood to mean in particular a body which displaces another element in a switching direction by means of a movement in an actuating direction, the switching direction preferably being different from the actuating direction. Particularly advantageously, the switching direction is orthogonal to the actuating direction. 
     It is further proposed that the at least one displacement body is provided to be adjusted so as to shift the cam unit to the third cam track. As a result, the third cam track can particularly advantageously be switched by means of the one displacement body. 
     It is further proposed that the switch unit has at least two displacement bodies which are provided so as to be separated from the cam unit at the same time in a switch preparation for activating and/or deactivating the third cam track. As a result, a switching of the switch unit to the third cam track can be prepared in a particularly simple manner. In this case, “activating a cam track” is to be understood in particular to mean a switching process which brings the corresponding cam track into engagement with the valve to be actuated. In this case, “deactivating a cam track” is to be understood in particular to mean a switching process which moves the corresponding cam track out of engagement with the valve to be actuated. In this case, “separated from the cam track at the same time” should be understood to mean, in particular, that the two displacement bodies are not in direct contact with the cam unit, at least for a defined period of time. 
     It is furthermore proposed that the valve train device has at least one shifting element which is provided to adjust at least part of the switch unit axially with respect to the support element. As a result, the switch unit together with the two displacement bodies thereof can advantageously be used for switching the three cam tracks. A “shifting element” is to be understood to mean, in particular, an element which has at least one actuator for shifting another element, in particular the switch unit, by means of which actuator the element can be axially shifted between at least two switch positions. In this case, the actuator of the shifting element is preferably designed as an actuator that a person skilled in the art deems appropriate, in particular as a spindle drive having an electric motor. In principle, it is also conceivable that the actuator is designed as a pneumatic or hydraulic actuator. 
     It is also proposed that the at least one shifting element is arranged inside the switch unit. As a result, the shifting element and the switch unit can be particularly advantageously formed integrally with each other, as a result of which they can be arranged particularly easily in the housing of the valve train device. 
     It is additionally proposed that the at least one shifting element is provided to axially shift the at least one displacement element inside the switch unit. As a result, the shifting element can be designed to be particularly advantageous and operationally reliable. 
     It is furthermore proposed that the at least one shifting element is arranged inside the switch unit. As a result, the shifting element can be designed to be particularly cost-effective. 
     It is additionally proposed that the at least one shifting element is provided to axially shift the entire switch unit. As a result, an adjustment of the switch unit between a first switch position and a second switch position can be carried out particularly easily. 
     Further advantages can be found in the following description of the drawings. Two embodiments of the invention are shown in the drawings. The drawings, the description of the drawings and the claims contain numerous features in combination. A person skilled in the art will expediently also consider the features individually and combine them to form appropriate further combinations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic representation of a valve train device according to the invention in a first embodiment comprising a cam unit in a second switch position; 
         FIG. 2  is a schematic representation of the valve train device comprising the cam unit in a third switch position, 
         FIG. 3  is a schematic representation of the valve train device comprising the cam unit in a second switch position together with a switch unit in an intermediate position; 
         FIG. 4  is a schematic representation of the valve train device comprising the cam unit in a second switch position together with the switch unit in a second switch position; 
         FIG. 5  is a schematic representation of the valve train device comprising the cam unit in a first switch position together with the switch unit in the second switch position; and 
         FIG. 6  is a schematic representation of a valve train device according to the invention in a second embodiment comprising a cam unit in a third switch position and a switch unit in a first switch position. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIGS. 1 to 5  are schematic representations of a valve train device according to the invention. The valve train device is part of an internal combustion engine (not shown in more detail). The internal combustion engine is designed as a motor vehicle internal combustion engine, which is provided to convert chemical energy into kinetic energy, which is used in particular for propulsion of a motor vehicle. The internal combustion engine in this case has a plurality of cylinders, each having a plurality of valves  16 ,  17 . The internal combustion engine has two valves  16 ,  17  designed as intake valves and two valves designed as exhaust valves. In principle, it is also conceivable that the internal combustion engine has a different number of valves  16 ,  17 . The valves  16 ,  17  are shown schematically by their actuation level in  FIG. 1-5 . 
     The valve train device is provided for actuating the valves  16 ,  17  of the internal combustion engine. The valve train device has a camshaft  10  for actuating the valves  16 ,  17 . In  FIG. 1 , only a part of the camshaft  10  that is associated with a cylinder is shown. The camshaft  10  is mounted in a support element  14  that is secured to the housing. In principle, it is also conceivable that the support element  14  is designed as a housing of the valve train device. Furthermore, the valve train device has a further camshaft which is not shown in more detail. The camshaft  10  shown is designed, by way of example, as an intake camshaft and the camshaft which is not shown in more detail as an exhaust camshaft. In the following, only the part of the camshaft  10  described in  FIG. 1  will be described in more detail. The description can be transferred to the part of the camshaft  10  not shown in more detail and to the camshaft not shown in more detail. 
     The camshaft  10  is rotatably mounted in a valve train housing which is not shown in more detail. The camshaft  10  is mounted so as to rotate about a rotational axis  11 . The rotational axis  11  of the camshaft  10  is oriented so as to be substantially parallel to a rotational axis of a crankshaft of the internal combustion engine. The camshaft  10  is driven by means of a coupling (not shown in more detail) of the crankshaft. The valve train device comprises one cam unit  12  per cylinder. In principle, it is also conceivable that the valve train device has a different number of cam units  12  per cylinder. The cam unit  12  is formed by a cam element  13 . In principle, it is also conceivable that the cam unit  12  is formed by a plurality of cam elements  13 . 
     The cam element  13  is arranged so as to be axially shiftable on the camshaft  10 . In this case, the cam element  13  is coupled to the camshaft  10  for conjoint rotation. The cam element  13  is connected to the camshaft  10  in particular by means of teeth (not shown in more detail). The cam element  13  is provided for actuating the valves  16 ,  17 . The cam element  13  has three cam tracks  18 ,  19 ,  20 ,  18 ′,  19 ′,  20 ′ for each valve  16 ,  17 . In principle, it is also conceivable that the cam element  13  has only two or more than three cam tracks  18 ,  19 ,  20 ,  18 ′,  19 ′,  20 ′ for each valve  16 ,  17 . The cam tracks  18 ,  19 ,  20 ,  18 ′,  19 ′,  20 ′ each have different contours and thus actuate the relevant valve  16 ,  17  with correspondingly different valve lifts. In a first switch position of the cam element  13 , the first cam tracks  18 ,  18 ′ actuate the relevant valve  16 ,  17 . In a second switch position of the cam element  13 , the second cam tracks  19 ,  19 ′ actuate the relevant valve  16 ,  17 . In a third switch position of the cam element  13 , the third cam tracks  20 ,  20 ′ actuate the relevant valve  16 ,  17 . The actuation of a valve  16 ,  17  by a cam track  18 ,  19 ,  20 ,  18 ′,  19 ′,  20 ′ takes place in a manner known to a person skilled in the art. 
     In order to adjust the cam element  13  on the camshaft  10  between the three switch positions, the valve train device has a switch unit  15 . The switch unit  15  is provided to shift the cam element  13  axially on the camshaft  10  in order to bring the different cam tracks  18 ,  19 ,  20 ,  18 ′,  19 ′,  20 ′ into engagement with the relevant valve  16 ,  17 . In this case, the switch unit  15  is provided to adjust the cam element  13  between the switch positions using a displacement principle. The switch unit  15  is provided to adjust the cam element  13  by means of a displacement, in particular orthogonally to an actuating direction of the switch unit  15 . 
     The switch unit  15  comprises a displacement body  21  for axially shifting the cam element  13  in a first switching direction  23 . The displacement body  21  is provided to displace at least part of the cam unit  12  in order to axially shift the cam unit  12 . In order to axially shift the cam element  13 , the displacement body  21  is provided to be introduced operatively between the support element  14  and the cam element  13 . The displacement body  21  has a width which corresponds to a shift path of the cam element  12  between two switch positions of immediately adjacent cam tracks  18 ,  19 ,  20 ,  18 ′,  19 ′,  20 ′. The width of the displacement body  21  corresponds to a width of a cam path  18 ,  19 ,  20 ,  18 ′,  19 ′,  20 ′. The cam element  13  forms a displacement contour  22 , which is designed so as to correspond to the displacement body  21 . The displacement contour  22  is provided so that the displacement body  21  for adjusting the cam element  13  comes into frictional contact therewith. The displacement contour  22  is designed as an edge of a groove  29  in the cam element  13 . In this case, the circumferential groove  29  has a width that corresponds to the width of the displacement body  21 . The displacement body  21  has an oblique contact surface  27 . When the displacement body  21  operatively slides in, the oblique contact surface  27  of the displacement body  21  touches the cam element  13  first. The displacement body  21  has a wedge shape which forms the oblique contact surface  27 . When the displacement body  21  slides in toward the cam element  13  in the radial direction, the oblique contact surface  27  engages laterally against the displacement contour  22  of the cam element  13 . When the displacement body  21  slides in further, the cam element  12  slides off the oblique contact surface  27  and is shifted by the displacement body  21  in the first switching direction  23 . In a switching process, the oblique contact surface  27  of the displacement body  25  is pressed against the displacement contour  22  of the cam element and thereby displaces the cam element  13  in one of the first switching directions  23 . 
     The switch unit  15  comprises a further displacement body  25  for axially shifting the cam element  13  in a second switching direction  24 . The second switching direction  24  is opposite to the first switching direction. The displacement body  25  is provided to displace at least part of the cam unit  12  for axial displacement of the cam unit  12 . In order to axially shift the cam element  13 , the displacement body  25  is provided to be introduced operatively between the support element  14  and the cam element  13 . The displacement body  25  has a width which corresponds to a shift path of the cam element  12  between two switch positions, of immediately adjacent cam tracks  18 ,  19 ,  20 ,  18 ′,  19 ′,  20 ′. The width of the displacement body  25  corresponds to a width of a cam path  18 ,  19 ,  20 ,  18 ′,  19 ′,  20 ′. The cam element  13  forms a second displacement contour  26 , which is designed so as to correspond to the displacement body  25 . The displacement contour  26  is provided so that the displacement body  25 , in order to adjust the cam element  13 , comes into frictional contact therewith in the second switching direction  24 . The displacement contour  26  is designed as an edge of a groove  30  in the cam element  13 . In this case, the circumferential groove  30  has a width that corresponds to the width of the displacement body  25 . The displacement body  25  has an oblique contact surface  28 . When the displacement body  25  operatively slides in, the oblique contact surface  28  of the displacement body  25  touches the cam element  13  first. The displacement body  25  has a wedge shape which forms the oblique contact surface  28 . In this case, the oblique contact surface  28  of the second displacement body  25  is mirror-symmetrically oriented with respect to the oblique contact surface  27  of the first displacement body  21 . In a switching process, the oblique contact surface  28  of the displacement body  25  is pressed against the displacement contour  22  of the cam element and thereby displaces the cam element  13  in one of the second switching directions  24 . 
     In an operating state in which the cam element  13  is not shifted axially between the switch positions thereof, the displacement bodies  21 ,  25  each form a thrust bearing for the cam element  13 . In designing the thrust bearing for the cam element  13 , the displacement bodies  25 ,  26  each form axial stops for the cam element  13 , in which they are arranged in the corresponding groove  29 ,  30  in the cam element  13 . In principle, it is also conceivable that the displacement bodies  21 ,  25  and the corresponding displacement contours  22 ,  26  are designed in another way that a person skilled in the art deems appropriate. It is conceivable, for example, that the displacement contours  22 ,  26  are designed as ribs having an oblique contact surface. In this case, the displacement bodies  21 ,  25  would be designed to be correspondingly equivalent. 
     The displacement bodies  21 ,  25  are designed to be uncoupled. The displacement bodies  21 ,  25  are designed in particular to be switchable independently of each other. The switch unit  15  comprises an actuator  31 . The actuator  31  is provided for actuating the two displacement bodies  21 ,  25 . The switch unit  15  comprises an actuator  32 . The actuator  31  of the switch unit  15  is arranged inside the housing. The displacement bodies  21 ,  25  are mounted so as to be shiftable in the housing  32 . The displacement bodies  21 ,  25  can be shifted linearly in a radial direction. In a state in which the displacement bodies  21 ,  25  are operatively introduced into the cam element  13 , the displacement bodies  21 ,  25  are accommodated 60 percent in the housings  31 ,  32 . In order to adjust the displacement bodies  21 ,  25 , the actuator  31  comprises two switch actuators  33 ,  34  for radially moving the displacement bodies  21 ,  25 . The switch actuators  33 ,  34  are schematically indicated by the respective switching directions thereof, which each extend in the radial direction. The switch actuators  33 ,  34  are designed as actuators that a person skilled in the art deems appropriate. The switch actuators  33 ,  34  are provided to adjust the displacement bodies between two switch positions. In a first switch position, the displacement bodies  21 ,  25  engage the corresponding displacement contour  22 ,  26  of the cam element  13 . In a second switch position, the displacement bodies  21 ,  25  are spaced apart from the corresponding displacement contour  22 ,  26  of the cam element  13 . 
     The valve train device has a shifting element  35 . The shifting element  35  is provided to adjust at least part of the switch unit  15  axially with respect to the support element  14 . The shifting element  35  is provided in particular to axially adjust the entire switch unit  15 . For this purpose, the switch unit  15  is mounted in the housing of the valve train device so as to be axially shiftable. The switch unit  15  is mounted in the housing of the valve train device by means of a mounting unit (not shown in more detail). The switch unit  15  is mounted so as to be shiftable between two switch positions.  FIGS. 1 to 3  show a first switch position of the switch unit  15 .  FIGS. 4 to 5  show a second switch position of the switch unit  15 . For the purpose of switching, the switch unit  15  is provided so as to be axially shifted onto an outer cam track  18 ,  18 ′,  20 ,  20 ′ of the three cam tracks  18 ,  19 ,  20 ,  18 ′,  19 ′,  20 ′. Using the axial displacement of the switch unit  15 , which can perform two mutually opposite switching movements by means of its two displacement bodies  21 ,  25 , a third switch position of the cam element  13  can be achieved. The shifting element  35  is designed as an actuator that comprises an axially retractable actuating lever. In this case, the actuator is designed as an electronically controllable spindle drive. In principle, it is also conceivable that the actuator is designed as a pneumatic or hydraulic actuator. 
     In order to adjust the cam element into a first switch position in which the third cam tracks  18 ,  18 ′ engage the corresponding valve  16 ,  17 , the two displacement bodies  21 ,  25  are initially switched at the same time to a retracted switch position and thus separated from the cam element  13  of the cam unit  12 . As a result, an axial securing of the cam element  13  is released. Subsequently, the switch unit  15  is moved by means of the shifting element  35  in a pre-switch movement to the second switch position thereof. As a result, in order to shift the cam element  13  in the first switching direction  13 , the displacement body  21  is in a position with respect to the correspondingly formed displacement contour  22  of the cam element  13 , such that the contour can engage in an intended manner in order to switch the cam element  13 . After the adjustment of the switch unit  15  into its second switch position, the cam element  13  is switched by introducing the displacement body  21  to the displacement contour  22  of the cam element  13  in the first switching direction  23  and thereby switched to the first switch position. In order to switch the cam element  13  between the first switch position in which the outer cam tracks  18 ,  18 ′ are engaged and the third switch position of the cam element  13  in which the outer cam tracks  20 ,  20 ′ are engaged, the switch unit  15  is shifted by means of the shifting element  35  in each case in a pre-switch movement axially with respect to the support element  14 . 
       FIG. 6  shows a further embodiment of the invention. The following descriptions and the drawings are substantially restricted to the differences between the embodiments, in which, in principle, reference can also be made, with respect to identically designated components, in particular with respect to components with the same reference signs, to the drawings and/or the description of the other embodiments, in particular  FIGS. 1 to 5 . To distinguish the embodiments the letter “a” is placed after the reference signs of the embodiment in  FIGS. 1 to 5 . In the embodiments of  FIG. 6  the letter “a” is replaced by the letter “b”. 
       FIG. 6  schematically shows a valve train device according to the invention in a second embodiment. The valve train device is part of an internal combustion engine (not shown in more detail). The internal combustion engine is designed as a motor vehicle internal combustion engine, which is provided to convert chemical energy into kinetic energy, which is used in particular for propulsion of a motor vehicle. The internal combustion engine has in this case a plurality of cylinders, each having a plurality of valves  16   b ,  17   b . The valve train device is provided for actuating the valves  16   b ,  17   b  of the internal combustion engine. The valve train device has a camshaft  10   b  for actuating the valves  16   b ,  17   b . The camshaft  10   b  is mounted in a support element  14   b  that is secured to the housing. In principle, it is also conceivable that the support element  14   b  is designed as a housing of the valve train device. The camshaft  10   b  is mounted so as to rotate about a rotational axis  11   b . The valve train device comprises one cam unit  12   b  per cylinder. In principle, it is also conceivable that the valve train device has a different number of cam units  12   b  per cylinder. The cam unit  12   b  is formed by a cam element  13   b . In principle, it is also conceivable that the cam unit  12   b  is formed by a plurality of cam elements  13   b.    
     The cam element  13   b  is arranged so as to be axially shiftable on the camshaft  10   b . In this case, the cam element  13   b  is coupled to the camshaft  10   b  for conjoint rotation. The cam element  13   b  is connected to the camshaft  10   b  in particular by means of teeth (not shown in more detail). The cam element  13   b  is provided for actuating the valves  16   b ,  17   b . For this purpose, the cam element  13   b  has three cam tracks  18   b ,  19   b ,  20   b ,  18   b ′,  19 ′,  20 ′ per valve  16   b ,  17   b . The cam unit  12   b  is substantially the same design as the corresponding cam unit from the first embodiment. 
     In order to adjust the cam element  13   b  on the camshaft  10   b  between the three switch positions, the valve train device has a switch unit  15   b . The switch unit  15   b  comprises a displacement body  21   b  for axially shifting the cam element  13   b  in a first switching direction  23   b . The displacement body  21   b  is provided to displace at least part of the cam unit  12  in order to axially shift the cam unit  12 . The switch unit  15   b  comprises a further displacement body  25   b  for axially shifting the cam element  13   b  in a second switching direction  24   b.    
     The displacement bodies  21   b ,  25   b  are designed to be uncoupled. The displacement bodies  21   b ,  25   b  are designed in particular to be switchable independently of each other. The switch unit  15   b  comprises an actuator  31   b . The actuator  31   b  is provided for actuating the two displacement bodies  21   b ,  25   b . The switch unit  15   b  comprises a housing  32   b . In order to adjust the displacement bodies  21   b ,  25   b , the actuator  31   b  comprises two switch actuators  33   b ,  34   b  for radially moving the displacement bodies  21   b ,  25   b . The switch actuators  33   b ,  34   b  are schematically indicated by the respective switching directions thereof, which each extend in the radial direction. 
     The valve train device has a shifting element  35   b . The shifting element  35   b  is provided to adjust at least part of the switch unit  15   b  axially with respect to the support element  14   b . In contrast to the first embodiment, the shifting element  35   b  is arranged inside the housing  32   b . The shifting element  35   b  is provided to adjust the two displacement bodies  21   b ,  25   b  inside the housing  32   b  of the switch unit  15   b . In  FIG. 6 , the displacement bodies  21   b ,  25   b  are shown in a first switch position and indicated by dashed lines in a second switch position.