Switching element for a valve train of an internal combustion engine

Abstract

In a switching element (1) for a valve train of an internal combustion engine for switching to different valve lifts, said switching element (1) comprising an outer element (2) having an inner element (4) arranged for axial displacement therein, each of the outer and the inner element (2, 4) comprising a reception (11, 9) aligned to each other in a relative position, at least one piston (10) being arranged in at least one of the receptions (11, 9) for sliding toward the other of the receptions (9, 11) to couple the inner element (4) to the outer element (2) in said relative position, and a high-position stop for defining said relative position being arranged between the inner and the outer element (4, 2), at least one part of the high-position stop is configured as an adjustable, separate element (13). This element (13) cooperates through a preferably conical section (15) of its outer periphery with a complementary chamfer (18) on one end (17) of a guide (16) in the outer element (2). By these extremely simple fabrication measures, an aligned adjustment of the receptions (9, 11) is created for effecting coupling.

Description

to a predetermined value in the range of one tenth of a millimeter and the tolerance is in the range of one hundredth of a millimeter.

The invention will now be described more closely with reference to the appended drawing.

BRIEF DESCRIPTION OF THE DRAWING

The sole FIGURE shows, in a longitudinal section, a switching element of the invention made in the present case as a roller tappet for a tappet push rod drive.

DETAILED DESCRIPTION OF THE DRAWING

The FIGURE discloses a switching element 1 that is configured as a roller tappet. The switching element is designed for switching to different valve lifts, in the present case, for switching between a zero lift and a full lift. The switching element 1 comprises an outer element 2 in whose recess 3 an inner element 4 is received for axial displacement.

On one end, the switching element 1 comprises a roller 5 for contacting a cam and acts at the opposite end through a support 6 on a tappet push rod in lifting direction. In the present example, the support 6 is a part of a hydraulic lash adjuster 7.

A lost motion spring 8 that does not need to be described here, acts axially between the inner element 4 and the outer element 2. The inner element 4 comprises a radially extending cylindrical reception 9 in which a piston 10 for coupling the inner element 4 to the outer element 2 is received. The piston 10 is biased radially outward by the force of a compression spring 11a. In the relative position of the inner element 4 to the outer element 2 shown in the FIGURE, a reception 11 in the outer element 2 is situated opposite the piston 10. For coupling, the piston 10 can be displaced partially into the reception 11 by the force of the compression spring 11a.

The inner element 4 comprises a recess 12 that is arranged diametrically opposite and axially aligned to the reception 9. A piston-like element 13 forming a high-position stop (and also an anti-rotation device between the inner element 4 and the outer element 2) extends with an inner peripheral section 14 in the recess 12.

A radially outer peripheral section 15 of the element 13 extends into a guide 16 made as a longitudinal groove in the outer element 2. The length of the guide 16 is at least equal in dimension to a relative travel of the inner element 4 to the outer element 2 in the deactivated or uncoupled state of the switching element 1. An upper end 17 of the guide 16 defines a stop for the adjustable, separate element 13 of the invention. The outer peripheral section 15 of the element 13 has a conical configuration. The end 17 comprises a chamfer 18 of complementary shape to this conical configuration.

As described in detail above, it is possible with the adjustable, separate piston-like element 13, to realize in a very simple manner from the fabrication point of view, an alignment of the reception 9 for the piston 10 to the reception 11 in the outer element 2. For achieving this, when the element 13 is being pressed into the recess 12, it is pressed axially toward the reception 9 for the piston 10 till the piston 10, of course in the unloaded state of the switching element 1, is surrounded by the reception 11 uniformly and with slight lash upon coupling. In this way, an idle travel that the inner element 4 undergoes with the piston 10 in the reception 11 relative to the outer element 2 upon coupling to the outer element 2 and at the onset of loading by the cam is uniformly small throughout a series of switching elements 1 in internal combustion engines of the same type.

Claims

1. A switching element for a valve train of an internal combustion engine for switching to different valve lifts, said switching element comprising an outer element having an inner element arranged for axial displacement therein, each of the outer element and the inner element comprising a reception aligned to each other in a relative position, at least one piston being arranged in at least one of the receptions for sliding toward the other of the receptions to couple the inner element to the outer element in said relative position, and a high-position stop for defining said relative position being arranged between the inner element and the outer element, wherein at least one part of the high-position stop is configured as an adjustable, separate piston element, the adjustable, separate element is a piston-like element, a first section of whose outer periphery is fixed in a recess of one of the inner element and the outer element, and a second section of whose outer periphery engages a guide that is made as a slot in the other of the inner element and the outer element and has a length that is at least equal to a relative motion between the inner element and the outer element, one end of the guide forms a further part of the high-position stop, and at least that end of the piston-like element that is situated opposite said one end of the guide comprises a chamfer that bears against a complementary chamfer of the said one end of the guide in the relative position, said piston-like element being axially displaceable in the relative position for establishing an alignment of the receptions of the inner and the outer element having a configuration for entry into a recess of one of the inner element and the outer element, opposite the receptions, to position the at least one piston so that mechanical lash of a predetermined value is provided between the at least one piston and at least one of the receptions.

2. A switching element of claim 1, wherein the second a section of the outer periphery of the piston-like separate piston element has a conical configuration.

3. A switching element of claim 1, wherein the piston-like separate piston element enables an alignment of the receptions of the inner outer element and the outer inner element so that upon coupling, in the unloaded state of the switching element, the at least one piston is uniformly surrounded with slight lash by the reception in which it is arranged.

4. A switching element of claim 1, wherein at least one of the first and the second sections of the outer periphery of the piston-like separate piston element is ground by centerless grinding.

5. A switching element of claim 1, wherein the at least one piston and the piston-like separate piston element are arranged in the inner element, and the recess of the inner element for fixing the piston-like separate piston element is aligned to the reception for the at least one piston in the inner element.

6. A switching element of claim 1, wherein the piston and the piston-like separate piston element are arranged in the inner element, and the recess of the inner element for fixing the piston-like separate piston element is made as a common bore with the reception for the piston in the inner element.

7. A series of switching elements of claim 1 for internal combustion engines of a same type wherein the alignment of the receptions of the inner outer element and the outer inner element is realized by the high-position stops of the switching elements so that a lash of the pistons, when coupled, relative to the receptions in which they are arranged is the same in all the switching elements of the series in an unloaded state of the switching elements.

8. A series of switching elements of claim 1 for internal combustion engines of a same type wherein a distance of the pistons, when coupled, from stops of the receptions in which they are arranged is the same in all the switching elements of the series in an unloaded state of the switching elements, said stops being situated axially opposite said one ends of the guides in the coupled state.

9. A switching element of claim 1 configured as one of a cam follower in a tappet push rod drive, a cup tappet and a support element for a finger lever.

10. A switching element for a valve train of an internal combustion engine for switching to different valve lifts, said switching element comprising an outer element having an inner element arranged for axial displacement therein, each of the outer element and the inner element comprising a reception aligned to each other in a relative position, at least one piston being arranged in at least one of the receptions for sliding toward the other of the receptions to couple the inner element to the outer element in said relative position, and a high-position stop for defining said relative position being arranged between the inner element and the outer element, wherein at least one part of the high-position stop is a separate piston element adjustable for entry into a recess of one of the inner element and the outer element, opposite the receptions, wherein the separate piston element comprises a first section having its outer periphery fixed in the recess of one of the inner element and the outer element, and a second section having its outer periphery engaging a guide that is made as a slot in the other of the inner element and the outer element, the guide having a length that is at least equal to a relative motion between the inner element and the outer element.

11. A switching element of claim 10, wherein one end of the guide forms a further part of the high-position stop, and at least that end of the separate piston element that is situated opposite said one end of the guide comprises a chamfer that bears against a complementary chamfer of the said one end of the guide in the relative position, the separate piston element being axially displaceable in the relative position for establishing an alignment of the receptions of the outer element and the inner element.

12. A switching element for a valve train of an internal combustion engine for switching to different valve lifts, said switching element comprising an outer element having an inner element arranged for axial displacement therein, each of the outer element and the inner element comprising a reception aligned to each other in a relative position, at least one piston being arranged in at least one of the receptions for sliding toward the other of the receptions to couple the inner element to the outer element in said relative position, and a high-position stop for defining said relative position being arranged between the outer element and the inner element, wherein at least one part of the high-position stop is configured as an adjustable, separate element, the adjustable, separate element is a piston element, having a first section disposed in a recess of the inner element and a second section engaging a guide in the outer element, said piston element being axially displaceable in the relative position and having a configuration selected for establishing an alignment of the receptions of the outer element and the inner element and for positioning the at least one piston so that mechanical lash of a predetermined value is provided between the at least one piston and at least one of the receptions.

13. A switching element of claim 12, wherein one end of the guide forms a further part of the high-position stop.

14. A switching element of claim 12, wherein at least that end of the piston element that is situated opposite said one end of the guide comprises a chamfer that bears against a complementary chamfer of the said one end of the guide in the relative position.

15. A switching element for a valve train of an internal combustion engine for switching to different valve lifts, said switching element comprising an outer element having an inner element arranged for axial displacement therein, each of the outer element and the inner element comprising a reception aligned to each other in a relative position, at least one piston being arranged in at least one of the receptions for sliding toward the other of the receptions to couple the inner element to the outer element in said relative position, and a high-position stop for defining said relative position being arranged between the outer element and the inner element, wherein at least one part of the high-position stop is configured as an adjustable, separate element, the adjustable, separate element is a piston element, having a first section disposed in a recess of the inner element and a second section engaging a guide in the outer element, said piston element being axially displaceable in the relative position for establishing an alignment of the receptions of the outer element and the inner element, wherein the guide has a length that is at least equal to a relative motion between the outer element and the inner element.

16. A deactivatable lifter for a valve train of an internal combustion engine, said deactivatable lifter comprising:

an outer element and an inner element positioned therein and arranged for axial displacement within said outer element to effect selective activation of an associated valve in the train;

a lost motion spring positioned axially between the outer element and the inner element, and acting on said inner element;

each of the outer element and the inner element having an opening aligned with each other in a relative position;

at least one coupling element being arranged in at least one of the openings for sliding movement toward or away from the other of the openings to couple to or decouple from the outer element to effect activation or deactivation, respectively, of said associated valve; and

a stop member including a separate adjustable element defining an upper limit of relative motion between said outer element and said inner element of said lifter, the separate adjustable element having a configuration to position the at least one coupling element so that mechanical lash of a predetermined value is provided between the at least one coupling element and at least one of the openings.

17. A deactivatable lifter of claim 16, wherein the predetermined value is on the order of 0.1 mm.

18. A deactivatable lifter of claim 16, wherein at least one of the outer element and the inner element is generally cylindrical in shape.

19. A deactivatable lifter of claim 16, wherein the lost motion spring is positioned in the outer element, underneath a lower surface of the inner element.

20. A deactivatable lifter of claim 16, wherein the separate adjustable element is adjustable to provide a selected assembly depth.

21. A deactivatable lifter of claim 16, wherein the separate adjustable element enables alignment between the openings of the inner element and the outer element to be adjusted.

22. A deactivatable lifter of claim 16, wherein the lost motion spring is positioned between a lower surface of the inner element and a part of the outer element below the lower surface of the inner element.

23. A deactivatable lifter of claim 22, wherein the part of the outer element is an inner surface of the outer element.