WO2018195370A1

WO2018195370A1 - Variable valve lift valve operating system having one or more motion control rings

Info

Publication number: WO2018195370A1
Application number: PCT/US2018/028467
Authority: WO
Inventors: Dale N. SMITH; Mark M. Wigsten
Original assignee: Borgwarner Inc.
Priority date: 2017-04-20
Filing date: 2018-04-20
Publication date: 2018-10-25

Abstract

A valve operating system that includes a cam tube, a cam member, and a motion control ring. The cam tube is rotatable about an axis. The cam member is axially slidably but non-rotatably mounted on the cam tube and movable along the axis between a first cam position and a second cam position. The cam member has a plurality of distinct and different cam configurations. The cam tube defines a first recess. The cam member defines an internal, circumferentially extending groove into which the motion control ring is received. The motion control ring is received in the first recess and frictionally engages the cam tube to resist movement of the cam member along the cam tube.

Description

VARIABLE VALVE LIFT VALVE OPERATING SYSTEM HAVING ONE OR MORE MOTION CONTROL RINGS

FIELD

[0001] The present disclosure relates to a variable valve lift valve operating system having one of more motion control rings.

BACKGROUND

[0002] This section provides background information related to the present disclosure which is not necessarily prior art.

[0003] A valve operating system having variable valve lift capabilities can include a rotary shaft onto which several sets of cam members are non- rotatably but axially slideably mounted. Each of the cam members can have two or more different sets of cam lobes that can be selectively and alternately employed to control the opening and closing of a set of valves. The cam members can be slid along the cam tube to position a particular set of the cam lobes at a location where they can actively participate in the opening and closing of the set of valves.

[0004] Due to the relatively high rotational speeds at which the switching between sets of cam lobes can occur, the need to switch between the alternative sets of cam lobes when the alternative sets of cam lobes are "on base circle", and the need to switch of all cam members be completed within one revolution of the cam tube, the switching between the sets of cam lobes typically involves the acceleration of the cam members in rather violent manner. It is desirable that all axial movement of the cam members along the cam tube be halted before the set of cam lobes is rotated off base circle. However, this can be due to the mass of the cam members, the relatively high acceleration with which the cam members are translated, and the high rotational speed of the cam members, the cam members may not have stopped moving in an axial direction by the time the set of cam lobes have rotated off base circle. SUMMARY

[0005] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0006] In one form, the present teachings provide a valve operating system that includes a cam tube, a cam member, and a motion control ring. The cam tube is rotatable about an axis. The cam member is axially slidably but non-rotatably mounted on the cam tube and movable along the axis between a first cam position and a second cam position. The cam member has a plurality of distinct and different cam configurations. The cam tube defines a first recess. The cam member defines an internal, circumferentially extending groove into which the motion control ring is received. The motion control ring is received in the first recess and frictionally engages the cam tube to resist movement of the cam member along the axis relative to the cam tube.

[0007] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

[0008] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0009] Figure 1 is a perspective view of a portion of an internal combustion engine having a valve operating system constructed in accordance with the teachings of the present disclosure;

[0010] Figure 2 is an exploded perspective view of the valve operating system of Figure 1 ;

[0011] Figure 3 is an exploded perspective view of a portion of the valve operating system of Figure 1 illustrating a cam tube and a plurality of cam assemblies in more detail;

[0012] Figure 4 is an exploded perspective view of a portion of one of the cam assemblies; [0013] Figure 5 is a schematic illustration of a portion of a cam member of one of the cam assemblies that depicts a portion of the cam member as having first and second cam configurations;

[0014] Figure 6 is similar to that of Figure 5, but also depicts a difference in the phasing of the first and second cam configurations;

[0015] Figure 7 is a longitudinal section view of a portion of the valve operating system of Figure 1 illustrating a motion control ring disposed in a cam member and engaged to an engagement surface formed on the cam tube;

[0016] Figure 8 is a longitudinal section view similar to that of Figure 7 but depicting a motion control ring disposed in a cam member and engaged to a first alternately configured engagement surface on a cam tube;

[0017] Figures 9 and 10 are longitudinal section views of the portion of the valve operating system of Figure 1 depicting the cam assemblies in first and second positions, respectively;

[0018] Figure 1 1 is a longitudinal section view similar to that of Figure 7 but depicting a motion control ring disposed in a cam member and engaged to a second alternately configured engagement surface on a cam tube;

[0019] Figure 12 is a perspective, partly exploded view of a portion of an exemplary valve operating system that incorporates the second alternately configured engagement surface on the cam tube that is depicted in Figure 1 1 ; and

[0020] Figure 13 is a longitudinal section view similar to that of Figure 7 but depicting a motion control ring disposed in a cam member and engaged to a second alternately configured engagement surface on a cam tube.

[0021] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

[0022] With reference to Figures 1 and 2, a portion of an internal combustion engine is illustrated as having a valve operating system 10 constructed in accordance with the teachings of the present disclosure.

Except as noted herein, the valve operating system 10 can be generally similar to that which is described in commonly assigned International Patent Application No. PCT/US2016/060244 filed November 3, 2016, the disclosure of which is incorporated by reference as if fully set forth in detail herein.

[0023] The internal combustion engine in the particular example illustrated is a four cylinder overhead cam engine with an in-line cylinder configuration, but it will be appreciated that the teachings of the present disclosure have application to other engine configurations and as such, it will be understood that the scope of the present disclosure is not limited to engines with an overhead cam engines or to engines with an in-line cylinder configuration. The engine can include a cylinder head CH and a drive means DM for providing rotary power to drive the valve operating system 10, such as a cam gear, cam sprocket or cam pulley. Except as otherwise noted herein, the cylinder head CH and drive means DM can be configured in a well-known and conventional manner. The valve operating system 10 can include a cam tube 12, a plurality of cam assemblies 14 and an actuator 16.

[0024] With reference to Figures 2 and 3, the cam tube 12 can be coupled to the drive means DM to receive rotary power therefrom. In the example provided, the cam tube 12 is fixedly and non-rotatably coupled to the drive means DM, but it will be appreciated that a variable coupling could be employed to couple the cam tube 12 to the drive means DM to selectively alter the rotational position of the cam tube 12 relative to the drive means DM within a predetermined range to provide the valve operating system 10 with variable valve timing capabilities. The cam tube 12 can have a hollow interior 20 and can define a plurality of cam member mounts 22 and a plurality of journals 24. The journals 24 can be received in a cam bore CB that can be formed between the cylinder head CH and a plurality of cam caps CC that are fixedly but removably coupled to the cylinder head CH. A plurality of bearings (not specifically shown) can be disposed between the journals 24 and the cylinder head CH and the cam caps CC so that the cam tube 12 is supported relative to the cylinder head CH for rotation about a rotary axis 28.

[0025] In Figures 2 and 4, each of the cam assemblies 14 can include a control link 30, one or more cam members 32 and one or more motion control rings 34. The control links 30 can have a link body 36 and one or more engagement members 38. The link body 36 can form a majority of the control link 30 and can extend within the hollow interior 20 of the cam tube 12 along the rotary axis 28 (i.e., parallel to the rotary axis 28). Each of the engagement members 38 can be coupled to the link body 36 for translation with the link body 36 along the rotary axis 28 and can extend radially outwardly from the link body 36. In the example provided, a first one of the engagement members 38a is formed of a component that is assembled to the link body 36 and secured together with a suitable coupling means, such as a weld and/or fasteners, while a second one of the engagement members 38b is unitarily and integrally formed with the link body 36 (e.g., as a hook or projection that extends perpendicular to the link body 36). It will be appreciated, however, that all of the engagement members 38 could be discrete components that are assembled and secured to the link body 36 or that all of the engagement members 38 could be unitarily and integrally formed with the link body 36, for example through bending, cold heading or forging.

[0026] Each of the cam members 32 can be axially slidably but non- rotatably coupled to the cam tube 12. In the example provided, each of the cam members 32 has an internally splined or toothed aperture 40 and is received over the cam tube 12 such that the internal teeth of the internally splined aperture 40 meshingly engage corresponding external teeth formed on the cam member mounts 22 on the cam tube 12.

[0027] Each of the cam members 32 can have a first cam configuration 50 and a second cam configuration 52 that are employed on an alternate basis to open a set of valves (not shown). Depending on the configuration of the engine, the set of valves may comprise solely one or more intake valves, or may comprise solely one or more exhaust valves, or may comprise both one or more intake valves and one or more exhaust valves. The first cam configuration 50 can have a first predetermined lift profile, while the second cam configuration 52 can have a second predetermined lift profile that is different from the first predetermined lift profile. With reference to Figure 5, the first predetermined lift profile could include one or more first cam lobes 56 that are configured to provide a first maximum lift value L1 (i.e., the maximum radius of the first cam lobe 56 minus the radius R of the base circle BC of the first cam lobe 56), while the second predetermined lift profile could include one or more second cam lobes 58 that are configured to provide a second maximum lift value L2 that is different from the first maximum lift value L1 . In situations where the first and second cam configurations 50 and 52 are configured to open a set of valves that comprises both one or more intake valves and one or more exhaust valves, it will be appreciated that the first and second cam lobes 56 and 58 (Fig. 5) mentioned previously are configured to open either the intake valve(s) or the exhaust valve(s), and that the first and second cam configurations 50 and 52 will additionally include one or more other cam lobes (not shown) that are configured to open the other type of valves (i.e., exhaust valves or intake valves) that are not opened by the first and second cam lobes 56 and 58 (Fig. 5). Additionally or alternatively, the first cam lobes 56 of the first predetermined lift profile could be timed (i.e., oriented about the rotary axis) differently from the second cam lobes 58 of the second predetermined lift profile as shown in Figure 6 and as represented by the angle A.

[0028] Returning to Figures 2 and 3, each of the cam members 32 of a given one of the cam assemblies 14 can be coupled to the control link 30 of the given one of the cam assemblies 14 for axial movement with the control link 30 along the rotary axis 28. In the example provided, each of the engagement members 38 of the control links 30 are received through respective slotted apertures 60 (best shown in Fig. 3) formed in the cam tube 12 and are received into (and optionally through) respective apertures 62 formed in a respective one of the cam members 32.

[0029] Each of the cam assemblies 14 is slide-able along the rotary axis 28 between a first position (Fig. 9), in which the first cam configurations 50 are positioned in associated activated locations 70 and each of the second cam configurations 52 is offset along the rotary axis 28 from their associated activated location 70, and a second position (Fig. 10), in which the second cam configurations 52 are positioned in the associated activated locations 70 and each of the first cam configurations 50 is offset along the rotary axis 28 from their associated activated location 70.

[0030] With reference to Figures 4 and 7, each of the motion control rings 34 is received between an associated one of the cam members 32 and the cam tube 12 and is configured to generate friction forces that not only resist movement of the associated one of the cam members 32 relative to the cam tube 12, but also which increases as the associated one of the cam assemblies 14 is moved between the first and second positions. Each of the motion control rings 34 is formed of a spring-wire material which can be formed of a wire having a desired cross-sectional shape, such as a round wire, a square wire or a rectangular wire. In the particular example provided, each motion control ring 34 is received into a circumferentially extending groove 100, which intersects the internally splined aperture 40, that is formed into an associated one of the cam members 32 and slidingly engages a corresponding engagement surface 102 that is formed on the cam tube 12. It will be appreciated, however, that in the alternative, the motion control ring 34 could be received in circumferentially extending groove (not shown) formed in the cam tube 12 and could slidingly engage a corresponding engagement surface (not shown) that is formed on the associated cam member 32.

[0031] The engagement surface 102 can define a plurality of recesses 104 and a connector 106. Each of the recesses 104 can define a seat 1 10 and one or more transition surfaces 1 12 that can be contoured in an appropriate manner between the seat 1 10 and an adjacent one of the connectors 106. Each of the transition surfaces 1 12 is tapered (i.e., frusto- conical) in the example provided, but it will be appreciated that each of the transition surfaces could be defined by one or more radii or combinations or one or more radii and one or more tapered segments.

[0032] In the example provided, each of the cam assemblies 14 is movable between first and second positions and as such, each engagement surface 102 has a single connector 106 that spans between a pair of the recesses 104. As such, each of the recesses 104 defines a single transition surface 1 12. It will be appreciated, however, that in situations where the cam assemblies 14 are movable into three or more positions, at least one of the recesses 104 can define a pair of transition surfaces 1 12 as is shown in Figure 8.

[0033] Returning to Figures 4 and 7, each of the motion control rings 34 can be received into an associated one of the circumferentially extending grooves 100 formed into the cam members 32 and in an associated one of the seats 1 10 that are formed in the cam tube 12. The motion control rings 34 are formed to a diameter that is somewhat smaller than that of the seats 1 10 so that each of the motion control rings 34 generates a radially-inwardly directed force that is exerted onto the surface of an associated seat 1 10. Axial movement of the motion control rings 34 along the cam tube 12 from an associated seat 1 10 to an associated transition surface 1 12 causes the motion control rings 34 to expand in diameter (so that the axial ends of the wire that forms the motion control rings 34 further separate from one another in a circumferential direction). It will be appreciated that this diametrical expansion of the motion control rings 34 causes an increase in the radially- directed force that is produced by the motion control rings 34 and as such, receipt of the motion control rings 34 in an associated one of the seats 34 tends to maintain the cam assemblies 14 relative to the cam tube 12 in an associated one of the first and second positions.

[0034] With reference to Figures 2, 9 and 10, during operation of the engine and rotation of the cam assemblies 14, the actuator 16 can be selectively operated to translate the cam members 32 along the rotary axis 28 to locate a desired one of the cam configurations 50, 52 on each of the cam members 32 at an associated activated location 70 so that the desired cam configurations 50, 52 on each of the cam members 32 is employed to open corresponding sets of valves.

[0035] With reference to Figures 7 and 9, movement of the cam assemblies 14 from one of the first and second positions toward the other one of the first and second positions causes movement of the cam members 32 relative to the cam tube 12 that drives the motion control rings 34 out of one of the seats 1 10, up an associated one of the transition surfaces 1 12 and onto an adjacent one of the connectors 106 so that the diameter of the motion control rings 34 is expanded and the motion control rings 34 generate relatively higher radially-inwardly directed forces. It will be appreciated that the radially-inwardly directed forces produced by the motion control rings 34 create friction forces when exerted against the engagement surfaces 102 to resist movement of the motion control rings 34 (as well as the cam members 32) along the cam tube 12. It will also be appreciated that the friction forces that are generated by the motion control rings 34 increase as the motion control rings 34 travel from an associated seat 1 10 to an associated connector 106. Further movement of the cam assemblies 14 toward their targeted positions causes the motion control rings 34 to move down the transition surfaces 1 12 that are on opposite side of the connectors 106 and into seats 1 10 that are associated with the placement of the cam assemblies 14 into their targeted positions. The friction forces produced as the motion control rings 34 are moved up one transition surface 1 12, over an associated one of the connectors 106 and down another of the transition surfaces 1 12 can help to decelerate the cam assemblies 14 as they are moved between the first and second positions.

[0036] While the engagement surface 102 has been illustrated and described as including a plurality of recesses 104 that have a seat 1 10 and one or more transition surfaces 1 12 that are disposed adjacent to the seat 1 10, it will be appreciated that the engagement surface 102 can be constructed somewhat differently. With reference to Figures 1 1 and 12, the engagement surface 102' can be formed with a pair of recesses 104' and a connector 106'. In this example, each of the recesses 104' consists of only a seat 1 10' and the connector 106' directly connects to each of the seats 1 10'. In this regard, the connector 106' is tangent to the seat 1 10'. Configuration in this manner permits the motion control ring 34 to provide a consistent amount of friction to the engagement surface 102' over the length of travel of the associated cam member 32. Moreover, the construction of the engagement surface 102' in this manner is suitable for use where the cam member(s) 32 have two or more cam configurations. With reference to Figure 12, a detent mechanism can optionally be employed with each cam assembly 14' and the cam tube 12'. An exemplary detent mechanism is depicted as having a pair of first detent recesses 150 (only one shown), a pair of second detent recesses 152 (only one shown), a pair of detent balls 154 and a band spring 156. The pairs of first and second detent recesses 150 and 152 are formed into the cam tube 12' on opposite sides. In this regard, each of the first detent recesses 150 is disposed 180 degrees apart from the other first detent recess 150, and each of the second detent recesses 152 is disposed 180 degrees apart from the other second detent recess 152. Each of the detent balls 154 is disposed in an associated hole 160 (only one shown) that is formed in a cam member 32a'. The band spring 156 is disposed about the cam member 32a' and biases the detent balls 154 radially inwardly toward the cam tube 12'. It will be appreciated that the detent balls 154 can engage one of the detent recesses 150, 152 when one of the cam configurations 50, 52 on the cam member 32a' is disposed in an associated activated location 70 (Fig. 9).

[0037] The example of Figure 13 is generally similar to that of Figure 1 1 , except that the circumferentially extending groove 100" for holding the motion control ring 34 that is formed into the cam member 32" can include one or more wedging surfaces 170. Each wedging surface 170 is configured to exert a force onto the motion control ring 34 that drives the motion control ring 34 into the seat 1 10' of the recess 104' in the engagement surface 102'. Configuration in this manner may help to prevent the cam member 32" from driving the motion control ring 34 out of the seat 1 10' and over-traveling. The example provided has but a single wedging surface 170 that is configured to drive the motion control ring 34 into a single one of the seats 1 10' (i.e., the seat 1 10' shown in the right side of the figure), but it will be appreciated that a second wedging surface (not shown) could be incorporated into an opposite side of the circumferentially extending groove 100" that would be configured to drive the motion control ring 34 into the other one of the seats 1 10' (i.e., the seat 1 10' shown on the left side of the figure). In situations where the cam assemblies have multiple cam members, another one of the cam members (not shown) could be configured with a circumferentially extending groove having another motion control ring received therein (for engaging a corresponding engagement surface) and the circumferentially extending groove could have a similar wedging surface that is disposed on an opposite side of the circumferentially extending groove than which is shown here. Accordingly, the wedging surface on a first one of the cam members can prevent over-travel of the cam members relative to the cam tube 12 in a first direction, while the wedging surface on a second one of the cam members can prevent over-travel of the cam members relative to the cam tube 12 in a second direction that is opposite the first direction.

[0038] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

What is claimed is:

1 . A valve operating system (10) comprising:

a cam tube (12) that is rotatable about an axis (28); and

a cam member (32, 32") axially slidably but non-rotatably mounted on the cam tube (12) and movable along the axis (28) between a first cam position and a second cam position, the cam member (32, 32") having a plurality of distinct and different cam configurations (50, 52);

characterized in that the cam tube (12) defines a first recess (104, 104'), the cam member (32, 32") defines an internal, circumferentially extending groove (100, 100"), and a motion control ring (34) is received in the internal, circumferentially extending groove (100, 100") in the cam member (32, 32"), wherein the motion control ring (34) is received in the first recess (104, 104') and frictionally engages the cam tube (12) to resist movement of the cam member (32, 32") relative to the cam tube (12).

2. The valve operating system (10) of Claim 1 , wherein the first recess (104, 104') has a first seat (1 10, 1 10') and wherein the motion control ring (34) engages the first seat (1 10, 1 10') when the cam member (32, 32" is disposed in the first cam position.

3. The valve operating system (10) of Claim 2, wherein the first recess (104, 104') has a transition surface (1 12), and wherein the transition surface (1 12) diverges outwardly from the first seat (1 10, 1 10') toward an outer circumferential surface (106) of the cam tube (12).

4. The valve operating system (10) of Claim 3, wherein the transition surface (1 12) is frusto-conical in shape.

5. The valve operating system (10) of Claim 2, wherein the internal, circumferentially extending groove (100") defines a wedging surface (170) that is configured to drive the motion control ring (34) in a radially inward direction into the first seat (1 10, 1 10').

6. The valve operating system (10) of Claim 5, wherein the wedging surface (170) is frusto-conical in shape.

7. The valve operating system of Claim 2, wherein the cam tube (12) defines a second recess (104, 104') with a second seat (1 10, 1 10') and wherein the motion control ring (34) is received in the second recess (104, 104') and engages the second seat (1 10, 1 10') when the cam member (32, 32") is disposed in the second cam position. 8. The valve operating system (10) of Claim 7, wherein the second recess (104, 104') has a transition surface (1 12), and wherein the transition surface (1 12) diverges outwardly from the second seat (1 10, 1 10') toward an outer circumferential surface (106) of the cam tube (12). 9. The valve operating system (10) of Claim 8, wherein the transition surface (1 12) is frusto-conical in shape.

10. The valve operating system (10) of Claim 7, wherein the cam tube (12) defines a third recess (104, 104') that is disposed along the axis (28) between the first recess (104, 104') and the second recess (104, 104'), the third recess (104, 104') having a pair of transition surfaces (1 12) that are disposed along the axis (28) on opposite sides of a third seat (1 10, 1 10'), and wherein the motion control ring (34) is received in the third recess (104, 104') and engages the third seat (1 10, 1 10') when the cam member (32, 32") is disposed in a third cam position that is disposed axially between the first cam position and the second cam position to thereby resist movement of the cam member (32, 32") along the axis (28) away from the third cam position

1 1 . The valve operating system (10) of Claim 7 wherein the internal, circumferentially extending groove (100") defines a wedging surface (170) that is configured to drive the motion control ring (34) in a radially inward direction into the second seat (1 10, 1 10').

12. The valve operating system (10) of Claim 1 1 , wherein the wedging surface (170) is frusto-conical in shape.

13. The valve operating system (10) of Claim 1 , further comprising a control link (30) received in the cam tube (12), the cam member (32, 32") being coupled to the control link (30) for movement therewith along the axis (28).

14. The valve operating system (10) of Claim 13, wherein the control link (30) comprises a link body (36), which extends parallel to the axis

(28), and an engagement member (38) that is fixedly coupled to the link body (36), the engagement member (38) protruding through a slotted aperture (60) formed in the cam tube (12) and being received into an aperture (62) in the cam member (32, 32").

15. The valve operating system (10) of Claim 1 , wherein the motion control ring (34) is formed of spring wire.

16. The valve operating system (10) of Claim 15, wherein the spring wire is formed of a round wire, a square wire or a rectangular wire.