SWITCHING ELEMENT FOR A VALVE TRAIN OF AN INTERNAL COMBUSTION ENGINE

Abstract

The disclosure relates to a switching element comprising an external part and an internal part, which is axially displaceable in a bore of the external part. At least one radially displaceable locking element is disposed within at least one receptacle of the internal part and includes a flattened portion on a radially outwardly directed end. At least one recess of the external part can be acted upon by a control pressure and the at least one locking element can thereby be radially displaced from the locking position into a release position. At least in a respective locking position, a chamber delimited by the at least one locking element is spatially separated from the at least one recess of the external part by a respective locking section. At least one bypass is designed, which indirectly fluidly connects the at least one recess of the external part and a respective chamber.

Claims

1. A switching element for a valve train of an internal combustion engine, the switching element comprising: an external part; an internal part, configured to be: i) axially displaced in a bore of the external part and, ii) displaced relative to the external part into a coupling position in which at least one radially extending receptacle of the internal part overlaps with at least one radially extending recess of the external part; and at least one locking element slidably guided within the at least one radially extending receptacle, the at least one locking element having a flattened portion on a radially outwardly directed end; and a locking section defined on the flattened portion of the at least one locking element, the locking section engaging in the at least one radially extending recess of the external part in a locking position of the at least one locking element and in the coupled position of the internal part and the external part; and the at least one radially extending recess of the external part is configured to be acted upon by a control pressure and the at least one locking element is configured to be radially displaced from the locking position to a release position, in which the at least one locking element is displaced radially inwardly into the at least one radially extending receptacle; and at least in the locking position of the at least one locking element, a chamber delimited by the at least one locking element is spatially separated from the at least one radially extending recess of the external part by the locking section; and at least one bypass is configured to indirectly fluidly connect the at least one radially extending recess of the external part and the chamber at least until the chamber is fluidly connected directly to the at least one radially extending recess during a course of displacement of the at least one locking element.

2. The switching element according to claim 1, wherein the at least one bypass is formed by a cut-out configured to widen the at least one radially extending receptacle at least in a mouth region thereof onto an outer jacket of the internal part, the cut-out extending radially into the at least one radially extending receptacle so that a passage is formed from the at least one radially extending recess of the external part, past the at least one locking element, and into the chamber at least until the chamber is directly fluidly connected to the at least one radially extending recess of the external part.

3. The switching element according to claim 1, wherein the at least one bypass is formed by a depression arranged on an outer jacket of the internal part, the depression connecting the at least one radially extending recess of the external part to a circumferential groove, and the circumferential groove is formed around the outer jacket of the internal part and is configured to receive an anti-rotation means for the at least one locking element arranged within the at least one radially extending receptacle, and the circumferential groove merges into the at least one radially extending receptacle.

4. The switching element according to claim 1, wherein the at least one bypass is formed by a depression formed on an inner jacket of the external part and fluidly connects the at least one radially extending recess of the external part to the at least one radially extending receptacle of the internal part.

5. The switching element according to claim 1, wherein the at least one bypass is formed by a cut-out of the at least one locking element.

6. The switching element according to claim 5, wherein the cut-out is arranged on a contact surface of the flattened portion of the at least one locking element, the contact surface configured to engage the external part in the locking position.

7. The switching element according to claim 5, wherein the cut-out is formed tangentially on a cylindrical guide surface on which the at least one locking element is slidably guided within the at least one radially extending receptacle of the internal part, and the respective cut-out forms a fluid passage from the at least one radially extending recess of the external part, past the at least one locking element via the cut-out, and into the chamber at least until the chamber is directly fluidly connected to the at least one radially extending recess of the external part via displacement of the at least one locking element within the radially extending receptacle.

8. The switching element according to claim 1, wherein the at least one bypass is formed by a channel which is defined in the at least one locking element and which opens into the chamber.

9. The switching element according to claim 8, wherein the channel extends from a front face of the locking section or from a cylindrical guide surface on which the at least one locking element is slidably guided within the at least one radially extending receptacle of the internal part.

10. The switching element according to claim 9, wherein the channel is formed by a single bore in the at least one locking element or by a plurality of bores which intersect within the at least one locking element.

11. A switching element for a valve train of an internal combustion engine, the switching element comprising: a cylindrical external part having: a first longitudinally extending bore; and at least one second radially extending bore; a cylindrical internal part configured to be axially displaceable within the first longitudinally extending bore, the cylindrical internal part having at least one radially extending receptacle; and at least one locking element disposed within the at least one radially extending receptacle, the at least one locking element having a flattened portion configured to engage the cylindrical external part in a first locking position of the at least one locking element, the flattened portion forming a chamber with the first longitudinally extending bore, the chamber directly fluidly disconnected from the at least one second radially extending bore in the first locking position; and the at least one second radially extending bore configured to receive a control pressure to move the at least one locking element to a second release position; and at least one bypass configured to indirectly fluidly connect the at least one second radially extending bore to the chamber in the first locking position.

12. The switching element of claim 11, wherein the at least one locking element has a cylindrical body configured to slidably engage the at least one radially extending receptacle.

13. The switching element of claim 12, wherein the at least one bypass is a cut-out arranged on a guide surface of the cylindrical body.

14. The switching element of claim 12, wherein the flattened portion comprises a contact surface configured to engage the cylindrical external part in the first locking position, and the at least one bypass extends from the contact surface to one of either a guide surface of the cylindrical body or an end face of the at least one locking element, the end face configured to receive the control pressure to move the at least one locking element from the first locking position to the second release position.

15. The switching element of claim 11, wherein a circlip configured to provide anti-rotation of the at least one locking element is disposed within the chamber.

16. The switching element of claim 11, wherein the at least one bypass comprises a depression on an outer jacket of the cylindrical internal part.

17. The switching element of claim 11, wherein the at least one bypass fluidly disconnects the at least one second radially extending bore from the chamber in the second release position of the at least one locking element, the cylindrical internal part configured to be axially displaceable relative to the cylindrical external part in the second release position.

18. The switching element of claim 11, wherein the at least one bypass is formed by at least one cut-out extending within the at least one radially extending receptacle.

19. The switching element of claim 11, wherein the at least one bypass is a channel configured within the at least one locking element.

20. A switching element for a valve train of an internal combustion engine, the switching element comprising: a cylindrical external part having: a first longitudinally extending bore; and at least one second radially extending bore; a cylindrical internal part configured to be axially displaceable within the first longitudinally extending bore, the cylindrical internal part having at least one radially extending receptacle; and two radially opposed locking elements disposed within the at least one radially extending receptacle, each of the two radially opposed locking elements configured to engage the cylindrical external part in a first locking position, each of the two radially opposed locking elements forming a chamber with the first longitudinally extending bore, the chamber directly fluidly disconnected from the at least one second radially extending bore in the first locking position; and the at least one second radially extending bore configured to receive a control pressure to move the two radially opposed locking elements to a second release position; and at least one bypass configured to indirectly fluidly connect the at least one second radially extending bore to the chamber in the first locking position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 shows a sectional view of a switching element according to the disclosure corresponding to a first embodiment of the disclosure;

[0027] FIG. 2 shows a further sectional view of the switching element from FIG. 1;

[0028] FIG. 3 shows a perspective individual view of an internal part of the switching element from FIG. 1;

[0029] FIG. 4 shows a further sectional view of the switching element from FIG. 1;

[0030] FIG. 5 shows a sectional view of a part of a switching element according to the disclosure according to a second possible embodiment of the disclosure;

[0031] FIG. 6 shows a perspective view of a part of the switching element from FIG. 5;

[0032] FIG. 7 shows a sectional view of a part of a switching element corresponding to the disclosure according to a third embodiment of the disclosure;

[0033] FIG. 8 shows a perspective individual view of an internal part of the switching element from FIG. 7;

[0034] FIG. 9 shows a sectional view of a part of a switching element according to the disclosure according to a fourth possible embodiment of the disclosure;

[0035] FIG. 10 shows a perspective individual view of a locking element of the switching element from FIG. 9;

[0036] FIG. 11 shows a sectional view of a part of a switching element according to the disclosure corresponding to a fifth embodiment of the disclosure;

[0037] FIG. 12 shows a perspective individual view of a locking element of the switching element from FIG. 11;

[0038] FIG. 13 shows a sectional view of part of a switching element according to the disclosure according to a sixth possible embodiment of the disclosure;

[0039] FIG. 14 shows a perspective individual view of a locking element of the switching element from FIG. 13;

[0040] FIG. 15 shows a sectional view of a part of a switching element corresponding to the disclosure according to a seventh embodiment of the disclosure;

[0041] FIG. 16 shows a perspective individual view of a locking element of the switching element from FIG. 15;

[0042] FIG. 17 shows a sectional view of part of a switching element according to an eighth possible embodiment of the disclosure; and

[0043] FIG. 18 shows a perspective individual view of a locking element of the switching element from FIG. 17.

DETAILED DESCRIPTION

[0044] FIG. 1 shows a sectional view of a hydraulic switching element 1 which is intended for use in a valve train of an internal combustion engine and is designed corresponding to a first embodiment of the disclosure. The switching element 1 comprises a hollow-cylindrical external part 2 and a cylindrical internal part 3, which is guided in an axially displaceable manner in the external part 2, particularly in a bore 4 of the external part 2. At an axial end 5, the external part 2 also supports a roller 6, which is provided in an installed state of the switching element 1 for contact with a lifting cam of a camshaft of the valve train. The internal part 3 also accommodates in an inner region 7 a play compensation element 8 which, in the installed state of the switching element 1, makes contact with a follower member, which is in particular a push rod. In this respect, the hydraulic switching element 1 is embodied here as a roller tappet.

[0045] A lost motion spring set 10 is also accommodated between a bottom region 9 of the external part 2 and the internal part 3, via which the internal part 3 is pretensioned axially in a direction of extension from the external part 2. In the installed state of the switching element 1, a permanent contact of the internal part 3 with the follower member is thereby ensured when the external part 2 contacts the lifting cam with the roller 6, even if the internal part 3 can be displaced axially relative to the external part 2.

[0046] As can be seen in FIG. 1 and also in the further sectional view in FIG. 2, the internal part 3 is radially interspersed with a through bore 11, which forms a receptacle 12 for two radially opposed locking elements 13 and 14. The locking elements 13 and 14 are each guided in a radially displaceable manner in the receptacle 12, wherein a radial insertion of the individual locking element 13 or 14 into the through bore 11 of the internal part 3 is limited by a stop in the form of a circlip 15. In addition, the locking elements 13 and 14 radially accommodate a spring element 16 therebetween, which in the present case is designed as a helical spring and pretensions the two locking elements 13 and 14 against one another radially outwards.

[0047] On the side of the external part 2 there is a recess 17 which is composed of a through bore 18 and an annular groove 19 connected thereto, and which can be supplied with hydraulic fluid radially from outside via the through bore 18. The through bore 18 penetrates the external part 2 in the radial direction, wherein the through bore 18 then merges radially on the side of the axially running bore 4 into the annular groove 19 which radially surrounds the internal part 3 in this axial region.

[0048] In FIG. 1, the external part 2 and the internal part 3 are positioned axially with respect to one another in a coupled position in which the through bore 11 and thus also the receptacle 12 of the locking elements 13 and 14 are overlapped by the recess 17. When there is no pressure supply to the recess 17, the locking elements 13 and 14 are each pretensioned radially outwards via the spring element 16 into a locking position in which the respective locking elements 13 and 14 are enclosed with a respective locking section 20 or 21 in the recess 17. As a result, the external part 2 and the internal part 3 are positively coupled to one another in the axial direction, so that the axial displacement of the internal part 3 relative to the external part 2 is prevented.

[0049] The respective locking section 20 or 21 of the individual locking element 13 or 14 is defined here by a flattened portion 22 or 23 - seen in FIG. 1 - which is respectively introduced into the individual locking element 13 or 14 in a respectively radially outwardly oriented end. The flattened portions 22 and 23 are used in the switching element 1 to prevent the locking elements 13 and 14 from rotating in the receptacle 12, in that an anti-rotation means 24 in the form of a circlip is enclosed in the flattened portions 22 and 23. The anti-rotation means 24 is accommodated in a circumferential groove 25 on the internal part 3, which can be seen in FIG. 3 in the perspective single view of the internal part 3, and is designed on an outer jacket 26 of the cylindrical internal part 3.

[0050] The flattened portions 22 and 23 also delimit a chamber 27 or 28 which defines the individual locking element 20 or 21 together with the receptacle 12 of the internal part 3 and an inner jacket 29 of the external part 2 formed by the bore 4.

[0051] The recess 17 of the external part 2 can be supplied with hydraulic fluid in the form of oil from the radial outside, thereby building up a control pressure which acts on the end faces of the locking sections 20 and 21 of the locking elements 13 and 14, and reaching a certain pressure threshold causes a radial insertion of the locking elements 13 and 14 from the locking positions shown in FIG. 1 against the spring element 16 in the receptacle 12. The locking elements 13 and 14 can be displaced completely into the receptacle 12 by the control pressure until they come into contact with the circlip 15 in a respective release position, so that the locking sections 20 and 21 are no longer enclosed in the recess 17 of the external part 2. As a result, the internal part 3 can be displaced axially relative to the external part 2.

[0052] However, in the respective locking position of the respective locking element 13 or 14, the respective chamber 27 or 28 is spatially separated and directly fluidly disconnected from the recess 17 by the respective locking section 20 or 21, so that hydraulic fluid initially cannot flow directly from the recess 17 into the respective chamber 27 or 28. This direct inflow can only take place from a displacement path in which the respective locking element 13 or 14 has already been displaced back radially so far into the receptacle 12 that the respective locking section 20 or 21 releases the respective chamber 27 or 28 from the recess 17 of the external part 2.

[0053] However, if the fluid connection between the chamber 27 and 28 and the recess 17 were not established until after this displacement path, this would briefly result in a drop in the control pressure, since the chamber 27 or 28 must first be filled with hydraulic fluid. To avoid this effect and also to be able to apply pressure to the individual locking element 13 or 14 on a larger surface at the front, bypasses 30 to 33 are provided in the switching element 1, via which the individual chamber 27 or 28 is fluidly connected indirectly to the recess 17.

[0054] As can be seen in FIGS. 2 to 4, the bypasses 30 to 33 are designed as cut-outs 34 to 37, which are designed in detail on a wall of the receptacle 12 in the force-free region, and starting from the mouth of the receptacle 12 extend to the outer jacket 26 of the internal part 3. Radially, the cut-outs 34 to 37 are designed with an extent such that hydraulic fluid can flow past the respective locking element 13 or 14 into the respective chamber 27 or 28.

[0055] Furthermore, FIGS. 5 and 6 show parts of a switching element 38 which is designed corresponding to a second possible embodiment of the disclosure and essentially corresponds to the previous variant according to FIGS. 1 to 4. The difference here, however, is that in this case an indirect fluid connection of the respective chamber 27 or 28 with the recess 17 of the external part 2 - not shown in FIGS. 5 and 6 but corresponding to the chamber shown in FIGS. 1 to 4 - is made via a bypass 39, which is introduced as a slit-like depression 40 in the outer jacket 26 of the internal part 3. This depression 40 spatially fluidly connects the annular groove 19 of the external part 2 with the groove 25 in which the anti-rotation means 24 is accommodated. Accordingly, via the depression 40, hydraulic fluid can permanently flow from the through bore 18 of the recess 17 via the annular groove 19 into the groove 25, which merges into the receptacle 12 and accordingly creates a spatial fluid connection between the respective chamber 27 or 28 and the depression 40. The indirect fluid connection of the recess 17 to the respective chamber 27 or 28 that is realized in this way is permanent. Otherwise, the possible embodiment according to FIGS. 5 and 6 corresponds to the variant according to FIGS. 1 to 4, so that reference is made to what has been described in this regard.

[0056] FIGS. 7 and 8 also show partial views of a switching element 41, which is designed according to a third embodiment of the disclosure and largely corresponds to the previous possible embodiment according to FIGS. 5 and 6. In this case, too, an indirect connection is established via a bypass 42, which is introduced as a depression 43 in the outer jacket 26 of the external part 3 and fluidly connects the groove 25 to the recess 17. In contrast to the variant according to FIGS. 5 and 6, the depression 43 is circular in this case. Otherwise, the embodiment according to FIGS. 7 and 8 corresponds to the variant according to FIGS. 5 and 6, so that reference is made to what has been described in this regard.

[0057] FIGS. 9 and 10 also show parts of a switching element 44 corresponding to a fourth possible embodiment of the disclosure, wherein the switching element 44 essentially corresponds to the variant according to FIGS. 1 to 4. Here, the switching element 44 is shown in FIG. 9 in the area of the individual locking element 13 or 14, which is respectively radially displaceably guided in the receptacle 12 of the internal part 3 as in the variant according to FIGS. 1 to 4. In contrast to the variant according to FIGS. 1 to 4, instead of bypasses on the internal part 3, a respective bypass 45 is now configured in the region of the individual locking element 13 or 14. As can be seen in conjunction with an individual view of the individual locking element 13 or 14 in FIG. 10, the bypass 45 is realized by a recess 46 in the form of a notch, which is designed on a contact surface 47.

[0058] This contact surface 47 is defined by the respective flattened portion 22 or 23, and makes axial contact with the annular groove 19 of the external part 2 in the respective locking position of the locking element 13. The cut-out 46 subsequently forms an indirect fluid connection of the respective chamber 27 or 28 with the recess 17 of the external part 2, wherein hydraulic fluid is able to flow from the recess 17 into the respective chamber 27 or 28 via this fluid connection. Otherwise, the possible embodiment according to FIGS. 9 and 10 corresponds to the variant according to FIGS. 1 to 4, so that reference is made to what has been described in this regard.

[0059] A respective bypass 49 is also implemented in the region of the respective locking element 13 or 14 in the case of a switching element 48, of which individual details are shown in FIGS. 11 and 12. The switching element 48 is implemented according to a fifth embodiment of the disclosure and essentially corresponds to the previous variant according to FIGS. 9 and 10. The only difference here is that the bypass 49 is formed in this case by a cut-out 50 which runs as a sloping bore 51 from an end face 52 of the respective locking section 20 or 21 to the respective chamber 27 or 28. The bore 51 opens out radially as a channel on the contact surface 47 in a region at which no contact is made with the external part 2 in the respective locking position. Accordingly, hydraulic fluid can flow directly from the recess 17 of the external part 2 via the bore 51 into the respective chamber 27 or 28. Otherwise, the embodiment according to FIGS. 11 and 12 corresponds to the variant according to FIGS. 9 and 10, so that reference is made to what has been described in this regard.

[0060] Likewise, in the further embodiments of a switching element 53 or 54 according to FIGS. 13 and 14, or 15 and 16, a respective bypass 55 or 56 is realized as a cut-out 57 or 58 in the respective locking element 13 or 14. In this respect, these embodiments essentially correspond to the variant according to FIGS. 11 and 12, wherein in contrast to the embodiment according to FIGS. 13 and 14, the cut-out 57 is realized by two holes 59 and 60, from which the hole 59 runs radially from the end face 52 and the hole 60 extends axially starting from the contact surface 47. Within the respective locking element 13 or 14, the two bores 59 and 60 intersect or meet and thereby together form the cut-out 57, via which as a new channel hydraulic fluid can flow permanently from the cut-out 17 into the respective chamber 27 or 28.

[0061] In contrast, in the embodiment according to FIGS. 15 and 16, the cut-out 58 in the respective locking element 13 or 14 is formed by a bore 61, which in this case, however, extends from a cylindrical guide surface 62 of the respective locking element 13 or 14 and through the respective locking element 13 or 14 so that it fluidly connects the recess 17 to the chamber 27. Accordingly, the bore 61 is covered by the receptacle 12 of the internal part 3 after a certain radial displacement of the respective locking element 13 or 14, and is therefore to be arranged in such a way that this covering or overlapping only occurs after a direct fluid connection of the chamber 27 or 28 to the recess 17. Otherwise, the embodiments according to FIGS. 13 and 14 as well as 15 and 16 correspond to the variant according to FIGS. 11 and 12, so that reference is made to what has been described in this regard.

[0062] Finally, FIGS. 17 and 18 show parts of a switching element 63 according to a further possible embodiment of the disclosure. This possible embodiment largely corresponds to the variant according to FIGS. 9 and 10, in that in this case a respective bypass 64 is implemented as a cut-out 65 in the region of the respective locking element 13 or 14. However, in contrast to the variant according to FIGS. 9 and 10, the respective cut-out 65 is formed tangentially on the cylindrical guide surface 62 of the respective locking element 13 or 14. As can be seen in particular in FIG. 17, this cut-out 65 is provided radially in a region of the cylindrical guide surface 62, so that in the respective locking position of the respective locking element 13 or 14, the indirect fluid connection of the respective chamber 27 or 28 with the recess 17 is already established and maintained until the respective chamber 27 or 28 and the recess 17 are directly fluidly connected to each other. In all other respects, the possible embodiment according to FIGS. 17 and 18 corresponds to the variant according to FIGS. 9 and 10, so that reference is made to what has been described in this regard.

[0063] The aforementioned variants of a switching element can be combined with one another as desired with regard to the design of one or a plurality of bypasses. A bypass in the region of the respective locking element can be combined with a bypass on the internal part.

[0064] A hydraulic switching element with improved switching characteristics can be created in each case by means of the configurations according to the disclosure.

TABLE-US-00001 LIST OF REFERENCE SYMBOLS 1 Switching element 2 External part 3 Internal part 4 Bore 5 End 6 Roller 7 Inner region 8 Play compensation element 9 Bottom region 10 Lost motion spring set 11 Through bore 12 Receptacle 13 Locking element 14 Locking element 15 Circlip 16 Spring element 17 Recess 18 Through bore 19 Annular groove 20 Locking section 21 Locking section 22 Flattened portion 23 Flattened portion 24 Anti-rotation means 25 Groove 26 Outer jacket 27 Chamber 28 Chamber 29 lnner jacket 30 Bypass 31 Bypass 32 Bypass 33 Bypass 34 Cut-out 35 Cut-out 36 Cut-out 37 Cut-out 38 Switching element 39 Bypass 40 Depression 41 Switching element 42 Bypass 43 Depression 44 Switching element 45 Bypass 46 Cut-out 47 Contact surface 48 Switching element 49 Bypass 50 Cut-out 51 Bore 52 End face 53 Switching element 54 Switching element 55 Bypass 56 Bypass 57 Cut-out 58 Cut-out 59 Bore 60 Bore 61 Bore 62 Guide surface 63 Switching element 64 Bypass 65 Cut-out