DE102019204589A1 - Valve drive for an internal combustion engine - Google Patents

Abstract

The invention relates to a valve drive (1), - with a camshaft (3) with a first cam (4) and a second cam (5) arranged adjacent thereto, - with a rocker arm assembly (6) with a sliding bolt adjustable in the axial direction (7) (8), on which a cam follower (9) is mounted, - with an adjusting device (11) and with an adjustable switching pin (12). It is essential to the invention that a guide contour (13) arranged on the camshaft (3) with a first guide track (14) and a second guide track (15) crossing it in an X-shape, - that the switching pin (12) engages either in the first or the second guide track (14, 15), - that the adjusting device (11) has a has shift rod (16) displaceable parallel to the shift bolt (8) with a first shift area (17), a second shift area (18) and a neutral area (19) arranged therebetween in the axial direction (7).

Description

The present invention relates to a valve drive for an internal combustion engine with a camshaft with a first and a second cam arranged adjacent thereto, according to the preamble of claim 1. The invention also relates to an internal combustion engine with such a valve drive.

From the DE 10 2017 205 571 A1 a generic valve drive for an internal combustion engine with a camshaft with a first and a second cam arranged axially adjacent thereto is known. The known valve drive has a rocker arm assembly with a sliding bolt which is adjustable in the axial direction between at least two positions and on which a cam follower, here a cam roller, is mounted. An adjustable switching pin of an adjusting device is arranged in the sliding bolt itself.

The cam follower can be adjusted between its two positions by the adjustment device and thus influence, in particular switch it on or off, a corresponding cylinder of the internal combustion engine. The known adjustment device has a first adjustable switching pin and a second adjustable switching pin, which each interact with a guide track arranged on the camshaft. However, due to the known adjusting device with two switching pins and the two separate guide tracks, the entire adjustment of the valve drive is only possible in a comparatively expensive manner.

The present invention therefore deals with the problem of specifying an improved or at least an alternative embodiment for a valve drive of the generic type, which is characterized in particular by a simplified structure.

This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject of the dependent claims.

The present invention is based on the general idea of providing a guide contour with two X-shaped crossing guide tracks in a valve drive known per se, whereby only a single adjustable switch pin is required for the adjustment. The valve drive according to the invention for an internal combustion engine has a camshaft with at least one first cam and a second cam arranged axially adjacent to it, as well as a rocker arm assembly with a sliding bolt that is adjustable in the axial direction between at least two positions and on which a cam follower, for example a cam roller, is mounted. In this case, a cam roller would, for example, be axially fixed and rotatably mounted on the sliding bolt. In the displacement bolt itself, a switching pin which can be adjusted radially to the displacement bolt by means of an adjustment device is arranged. According to the invention, the guide contour arranged on the camshaft is now equipped with a first guide track and a second guide track crossing this in an X-shape. The switching pin engages either in the first or the second guide track and thereby adjusts the sliding bolt between its two positions. The cam follower cooperates with the first cam in a first position of the sliding bolt and with the second cam in a second position of the sliding bolt. Valve opening times can be influenced by different cam profiles or a cylinder can be switched off. The adjustment device has a shift rod, which can be moved parallel to the shifting bolt, with a first shift range, a second shift range and a neutral range arranged between them in the axial direction of the shift rod, the shift pin in the first guide track on contact with the first shift range and in the second guide track is adjustable. With the valve drive according to the invention, it is thus possible to provide only a single switching pin on the sliding pin and to effect the adjustment of the sliding pin together with the guide contour according to the invention. With only a single switch pin required, it is possible to make the sliding bolt shorter in the axial direction and also to reduce the variety of parts and, associated therewith, the storage and logistics costs as well as the assembly effort. By providing the guide contour according to the invention with two intersecting guide tracks, the guide contour can also be built to be more compact and therefore space-saving overall. Overall, an adjustable valve drive can thus be implemented which, in comparison to the valve drive known from the prior art, is less complex, more cost-effective and, in particular, also requires less installation space.

In an advantageous further development of the solution according to the invention, the adjusting device has a housing in which the switching rod is guided and, in particular, is also supported. Such a housing can, for example, be of cylindrical design and have a casing opening via which the switching pin can be contacted with the switching areas. Such a cylindrical housing offers a particularly space-optimized solution, provided the shift rod is arranged coaxially in the housing. Through the jacket opening on the housing In addition, a protected arrangement of the shift rod and, in particular, an adjustment mechanism required to adjust the shift rod in the housing can be achieved, provided that the jacket opening in particular faces downwards, for example, so that oil hitting the housing jacket cannot penetrate into the housing.

In an advantageous development of the solution according to the invention, an electromagnet, in particular a coil surrounding the switching rod, and a permanent magnet arranged on the switching rod are provided, the switching rod being adjustable to its first or second position by energizing the electromagnet. By means of such an electromagnet, an inexpensive and extremely precise and low-maintenance actuation device for actuating the switching rod and thus for actuating the adjusting device can be achieved. Due to the coaxial arrangement of the electromagnet, in particular the coil and the permanent magnet arranged on the switching rod, a solution that is optimized in terms of installation space can also be created, which is also arranged in a protected manner in the housing.

In an advantageous further development of the solution according to the invention, at least one spring is provided which biases the shift rod into its first or second position. In this case, a solution is conceivable in which, for example, the electromagnet described above effects an adjustment of the shift rod into its first position by energizing it, while a return adjustment takes place exclusively by means of the spring. In this way, it can also be achieved that, in the event of failure of the electromagnet, a position of the switching rod predefined by the spring and thus a predefined cam tap is defined. Alternatively, it is of course also conceivable that two electromagnets, in particular two coils surrounding the switching rod and two permanent magnets arranged on the switching rod, are provided, the switching rod being adjustable to its first or second position by alternatively energizing the electromagnets. Such a solution is more expensive than a solution with a single solenoid and a spring, but it can, under certain circumstances, result in faster switching.

In an advantageous development of the solution according to the invention, the first switching area is arranged on the longitudinal end of the switching rod and is pot-shaped, the spring being designed as a helical spring and being at least partially arranged in the first switching area. In this case, the spring is thus supported at one end in the first switching area and at the other end, for example on a housing. This requires a protected arrangement of the spring not only in the housing, but also at least partially also in the first switching area, whereby a proper encapsulation of the spring and thus a particularly protected arrangement of the same can be achieved.

A position sensor is expediently provided by means of which a position of the shift rod and thus indirectly also a position of the sliding bolt or the valve drive can be detected. Such a position sensor can for example be designed as a Hall sensor. In particular, it is conceivable that such a position sensor monitors the position of the first or second switching range.

The first and / or second switching area expediently have / has a flattened area which is designed as a contact area for the switching pin. In this way, a flat contact with the switching pin can be achieved, whereby not only a punctual, but a flat distribution of the power transmission between the switching area and the switching pin is made possible and thereby in particular signs of wear can be minimized.

In a further advantageous embodiment of the solution according to the invention, the first and the second switching area have different diameters. This makes it possible, in particular, to compensate for different cam strokes in a comparatively simple manner.

The present invention is further based on the general idea of equipping an internal combustion engine with such a valve drive and thereby transferring the advantages of the valve drive described above to the internal combustion engine.

Further important features and advantages of the invention emerge from the subclaims, from the drawings and from the associated description of the figures on the basis of the drawings.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the present invention.

Preferred exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description, with the same reference symbols referring to the same or similar or functionally identical components.

• 1 einen erfindungsgemäßen Ventiltrieb für eine Brennkraftmaschine in einer Ansicht mit geschnittener Verstelleinrichtung,
• 2 eine Schnittdarstellung durch die Verstelleinrichtung gemäß der 1,
• 3 eine Darstellung wie in 2, jedoch bei einer anderen Ausführungsform,
• 4 eine Ansicht auf eine erfindungsgemäße Schaltstange mit zwei Schaltbereichen,
• 5a bis d unterschiedliche Schaltstellungen der Verstelleinrichtung.

They show, each schematically,

• 1 a valve drive according to the invention for an internal combustion engine in a view with a sectioned adjusting device,
• 2 a sectional view through the adjusting device according to FIG 1 ,
• 3 a representation as in 2 , but in a different embodiment,
• 4th a view of a shift rod according to the invention with two shift areas,
• 5a to d different switching positions of the adjustment device.

According to the 1 , has an inventive valve train 1 for an internal combustion engine not shown in detail 2 a camshaft 3 with a first cam 4th and a second cam disposed axially adjacent thereto 5 on. A rocker arm assembly is also provided 6th with one in the axial direction 7th between at least two positions adjustable sliding bolt 8th on which a cam follower 9 , especially a cam roller 10 , is stored. An adjustment device is also provided 11 (see also the 2 , 3 and 5) and an adjustable switch pin 12 that is in the sliding bolt 8th arranged, in particular is mounted radially in this. According to the invention is now on the camshaft 3 a guide contour 13 with a first lead 14th and a second guide track crossing these in an X-shape 15th arranged. The switch pin 12 selectively engages in the first or second guide track 14th , 15th a (according to the 1 into the first lead 14th ) and thereby adjusts the sliding bolt 8th with the cam followers arranged on it 9 between his / her two positions, the cam follower 9 , here the cam roller 10 , in a first position of the sliding bolt 8th with the first cam 4th and in the second position of the sliding bolt 8th with the second cam 5 cooperates. According to the 1 owns the rocker arm assembly 6th two cam followers 9 both coaxially on the sliding bolt 8th are rotatably arranged and each of which has either an associated first cam 4th or an associated second cam 5 cooperates.

The adjustment device 11 also has a parallel to the sliding bolt 8th , that is, in the axial direction 7th , sliding shift rod 16 (cf. also 4th ) with a first switching range 17th , a second switching range 18th and a neutral region disposed therebetween in the axial direction 19th on. The switch pin 12 is when there is contact with the first switching area 17th into the first lead 14th adjusted, while on contact with the second switching range 18th into the second guide lane 15th is adjusted. In the neutral range 19th is the switch pin 12 neither with the first switching range 17th , still with the second switching range 18th in contact (cf. 5a and 5c ), which means that the switch pin is not actuated 14th by the adjustment device 11 he follows. With the adjustment device according to the invention 11 it is possible in the sliding bolt 8th just a single switch pin 12 to have to arrange, whereby a structurally significantly less complex solution can be achieved with a smaller number of parts and with less assembly effort. By the guide contour according to the invention 13 with the X-shaped crossing guide tracks 14th , 15th can also have a guide contour 13 be created, which is space-optimized in particular in the axial direction and thus requires little space. Overall, with the valve train according to the invention 1 a structurally simple and space-optimized solution can be created.

If you look at the 1 to 5 further, so can see that the adjusting device 11 a housing 20th has, in which the shift rod 16 is guided or stored. The case 20th is cylindrical in the present case and has a shell opening 21st over which the switch pin 12 with the switching areas 17th , 18th can get in touch. The jacket opening 21st can be done centrally on the adjustment device 11 or also on one side at one end of the housing 20th be arranged. The shift rod 16 is comparatively easy to manufacture, for example by turning or thermally joining the two switching areas 17th , 18th on the shift rod 16 , whereby a structurally simple and thus inexpensive adjustment device as well 11 can be created. By the fact that the adjustment device 11 in the installed state (cf. 1 ), is arranged such that the jacket opening 21st pointing down is also the shift rod 16 inside the case 2 arranged protected, since in particular on the housing 20th hitting oil cannot penetrate into it.

For actuating or adjusting the switch rod 16 with the switching areas arranged on it 17th , 18th is preferably an electromagnet 22nd , especially in the manner of a shift rod 16 surrounding coil (cf. 2 ) or in the manner of a second switching range 18th surrounding coil (cf. 3 ) provided, and according to the 3 on the shift rod 16 a permanent magnet 23 is arranged. This permanent magnet 23 can of course also be inserted into the shift rod in another way 16 be integrated, as for example according to the 2 is shown. In theory, the shift rod can 16 also consist of a magnetizable material and thereby the adjustment of the shift rod 16 forces required by the electromagnet 22nd Experienced.

If you look at the 1 to 3 so you can see that at least one spring 24 is provided that the shift rod 16 and also the two switching areas 17th , 18th in their first or second position, here in their second position, biased. By means of such a spring 24 In particular, a fail-safe function can be implemented that has a predefined position of the shift rod 16 if the electromagnet fails 22nd or generally in the event of failure of an actuating device for adjusting the shift rod 16 , enforces. Alternative to the spring 24 can of course another electromagnet 22nd be provided, so that in this case a total of two electromagnets 22nd are provided which, with the appropriate current supply, the shift rod 16 adjust to their first or second position.

If you look at the 1 to 5 so you can see that the first switching range 17th longitudinal end of the shift rod 16 arranged and at the same time cup-shaped, the spring 24 , which in the present case is designed as a helical spring, at least partially in the first switching range 17th is arranged. This allows a protected arrangement of the spring 24 in the housing 20th and in the direction of the jacket opening 21st over the first switching range 17th protected arrangement can be achieved. A position sensor can also be provided 25th , for example a Hall sensor, via which a position of the shift rod 16 and thus a position of the two switching ranges 17th , 18th is detectable. In this way, for example, the exact switching position can be transmitted to an engine control unit.

The first and / or the second switching range 17th , 18th can be designed as a cylindrical table top. To make contact between the switch pin 12 and the respective switching range 17th , 18th to improve, it can also be considered that the first and / or second switching range 17th , 18th a flattened area 26th has, as the contact area to the switch pin 12 serves:

If one now considers the individual switching positions of the adjusting device according to the invention 11 according to the 5a to d so one can see that according to the 5a the actuator, i.e. in the present case the shift rod 16 , is retracted and the switch pin 12 in the neutral range 19th protrudes, in which no actuation of the same by the adjusting device 11 , that is, the first or second shift range 17th or 18th he follows. According to the 5b is now the adjustment device 11 activated. For example, by energizing the electromagnet 22nd causing the shift rod 16 has moved to the left and the switch pin 12 in contact with the second switching area 18th occurs. This will make the switch pin 12 moved down and thereby in the second guide track 15th adjusted. The switch pin now runs in this 12 and is in the axial direction 5 to the left in the neutral range 19th by means of the guide track 15th moved as per the 5c is shown. According to the 5d is the shift rod 16 move to the right again, causing the switch pin 12 now in contact with the first switching area 17th whereupon this the switch pin 12 into the first lead 14th adjusted. Overall, the 5a to d can be seen that the to switch from the first to the second cam 4th , 5 or back required travel of the shift rod 16 is comparatively short, which also helps to minimize the installation space. In addition, with the valve train according to the invention 1 only a single adjustment device 11 or a switch pin 12 and a guide contour 13 required per cylinder. Like that 1 to 5 can be seen further, both have switching ranges 17th , 18th different diameters to be able to compensate for different cam strokes.

With the valve train according to the invention 1 and the internal combustion engine designed therewith according to the invention 2 a structurally simple, inexpensive and also space-optimized solution for switching between different cam profiles can thus be achieved.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102017205571 A1 [0002]

Claims (11)

Valve drive (1) for an internal combustion engine (2), - with a camshaft (3) with a first cam (4) and a second cam (5) arranged adjacent to it, - with a rocker arm assembly (6) with an axial direction (7) between at least two positions adjustable displacement bolt (8) on which a cam follower (9), in particular a cam roller (10), is mounted, - with an adjusting device (11) for adjusting a switching pin (12) arranged in the displacement bolt (8), characterized in that - that a guide contour (13) arranged on the camshaft (3) is provided with a first guide track (14) and a second guide track (15) crossing it in an x-shape, - that the switching pin (12) can be inserted into the first or the second guide track (14, 15) engages and thereby displaces the sliding bolt (8) between its two positions so that the cam follower (9) is in a first position of the sliding bolt (8) with the first cam (4) and in a second position of the sliding bolt (8) cooperates with the second cam (5), - that the adjusting device (11) has a shift rod (16) which is displaceable parallel to the shifting bolt (8) and has a first shift range (17) and a second shift range (18) ) and a neutral area (19) arranged in between in the axial direction (7), the switching pin (12) in the first guide track (14) on contact with the first switching area (17) and in the second guide track (15) is adjusted. Valve train according to Claim 1 , characterized in that the adjusting device (11) has a housing (20) in which the switching rod (16) is guided. Valve train according to Claim 1 or 2 , characterized in that the first and / or the second indexing area (17, 18) are / is designed as cylindrical indexing plates. Valve train according to Claim 2 or 3 , characterized in that the housing (20) is cylindrical and has a jacket opening (21) via which the switching pin (12) can be contacted with the switching areas (17, 18). Valve drive according to one of the preceding claims, characterized in that an electromagnet (22), in particular a coil surrounding the shift rod (16), and in particular a permanent magnet (23) arranged on the shift rod (16), are provided, the shift rod (16) can be adjusted into its first or second position by energizing the electromagnet (22). Valve drive according to one of the preceding claims, characterized in that two electromagnets (22), in particular two coils surrounding the shift rod (16), and in particular two permanent magnets (23) arranged on the shift rod (16) are provided, the shift rod (16) can be adjusted into their first or second position by alternatively energizing the electromagnets (22). Valve drive according to one of the preceding claims, characterized in that at least one spring (24) is provided which biases the shift rod (16) into its first or second position. Valve train according to Claim 7 , characterized in that the first switching area (17) is arranged on the longitudinal end of the switching rod (16) and is pot-shaped, the spring (24) being designed as a helical spring and being at least partially arranged in the first switching area (17). Valve train according to one of the Claims 1 to 8th , characterized in that a position sensor (15) is provided, via which a position of the shift rod (16) can be detected. Valve drive according to one of the preceding claims, characterized in - that the first and / or the second switching area (17, 18) have a flattened area (26) which is designed as a contact area for the switching pin (12), and / or - that the first and second switching areas (17, 18) have different heights or diameters. Internal combustion engine (2) with a valve drive (1) according to one of the preceding claims.

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