GB2206380A - Axially movable camshaft valve gear - Google Patents
Axially movable camshaft valve gear Download PDFInfo
- Publication number
- GB2206380A GB2206380A GB08815067A GB8815067A GB2206380A GB 2206380 A GB2206380 A GB 2206380A GB 08815067 A GB08815067 A GB 08815067A GB 8815067 A GB8815067 A GB 8815067A GB 2206380 A GB2206380 A GB 2206380A
- Authority
- GB
- United Kingdom
- Prior art keywords
- lever
- valve
- support member
- valve arrangement
- arrangement according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
- F01L13/0015—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque
- F01L13/0036—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction
- F01L13/0047—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction the movement of the valves resulting from the sum of the simultaneous actions of at least two cams, the cams being independently variable in phase in respect of each other
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/12—Transmitting gear between valve drive and valve
- F01L1/14—Tappets; Push rods
- F01L1/143—Tappets; Push rods for use with overhead camshafts
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Valve-Gear Or Valve Arrangements (AREA)
Abstract
A pivoted member 18 is biased into engagement with profile adjusters 15 and 16 in which cams 11 ans 12 on the axially movable camshaft 10 are received. The cams 11 and 12 have lobes 13 and 14 of different shape and angular extent. Various arrangements for biasing the member 18 and pivoting the member on the support member 5, fixed to the valve stem 3, are described (Figs. 2 to 7). <IMAGE>
Description
Description of Invention "Improvements in or relating to valve arrangements"
THIS INVENTION relates to improvements in or relating to valve arrangements in which a lincarly movable valve member is displaced by a cam rotating with a camshaft.
The invention finds particular application to poppet valve arrangements as found in internal combustion engines.
The invention aims to provide a valve arrangement which offers a means of achieving variation in the timing, duration and extent of valve movements. Such an ability to vary the parameters of the valve event according to the operating conditions is desirable in that it can provide benefits in power and fucl economy and can assist in reducing obnoxious cmissions from the engine.
According to the present invention, there is provided a valve arrangement comprising a linearly movable valve member displaceable transversely of a fixed surface, an axially movable camshaft, a cam carried by the camshaft for rotational and axial movement therewith, transmission means for converting rotary motion of the cam into linear movement of the valve member and means for axially displacing the camshaft to provide stepless adjustment of the effectiveness with which the rotary motion of the cam is converted into linear movement of the valve member by the transmission means in order to vary a characteristic of the movement of the valve member, in which arrangement the transmission means comprises a support member fixedly attached to the valve member, a lever pivotally mounted on the support member for movement about a fulcrum and a compression spring engaged between the lever and the support member on the fixed surface in order to bias the lever into engagement with the cam, the cam acting on the lever at a distance from the fulcrum determined by the axial position of the -camshaft.
In order that the present invention may be more readily understood, embodiments thereof will now be described by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a diagrammatic, partly sectioned, front view of a first valve arrangement embodying the invention;
Figure 2 is a diagrammatic, partly sectioned, front view of a second valve arrangement embodying the present invention;
Figure 3 is a diagrmmatic, partly sectioned, front view of a third valve arrangement embodying the present invention;
Figure 4 is a diagrammatic, partly sectioned, front view of a fourth valve arrangement embodying the present invention;
Figure 5 is a side view, partly in section, of the valve arrangement of Figure 4;
Figure 5 is a side view, partly in section, of the valve arrangemnet of Figure It;; Figure 6 is a diagrammatic, partly sectioned, front view of a fifth valve arrangement embodying the present invention; and
Figure 7 is a side view, partly in section, of the valve arrangement of Figure 6.
In the various Figures of the drawings, like components of the various valve arrangements are indicated by the same reference numerals.
Referring initially to Figure 1 of the accompanying drawings, a first valve arrangement embodying the present invention comprises a conventional poppet valve 1 having a head 2 and an elongate stem 3. The poppet valve is of the type which is conventionally found in internal combustion engines. The head of the poppet valve is intended to cooperate with a valve seat (not shown). The elongate stem 3 of the valve passes through a conventional valve guide It and the upper end of the stem 3 is fixedly received within a recess formed in the underside of a valve bucket 5 which is slidably received within an aperture 6 formed in part of the conventional cylinder head 7. The upper surface of the bucket 5 is integrally formed with a projecting pivot seat 8 formed with a part spherical socket 9.
A camshaft 10 for controlling the operation of the valve 1 is rotatable about axis x-x and comprises a pair of cams 11 and 12 rotatable with the camshaft. The cams have respective lobes 13 and 14 of different angular extent and shape and are received in respective bifurcated profile adjusters 15 and 16 constrained to reciprocate parallel to the stem 3 of the valve 1 upon rotation of the cams 11 and 12 with the camshaft 9. The profile adjusters 15 and 16 have semi-cylindrical heads 15a, 16a engaging the upper surface of a circular transmission lever 18 disposed between the cams 11 and 12 and the valve bucket 5. Two bi-furcated arms 15b, 15e and 16b, 16c extend upwardly from the head of each profile adjuster, with the camshaft 10 passing through the bi-furcation of each arm of the profile adjuster.
The transmission lever 18 has a downwardly -depending peripheral circular rib 19 and a centrally disposed pivot boss 20 having a part spherical shape conforming to the shape of the pivot socket 9 in which it is freely received to form the fulcrum of lever 18.. The camshaft 10 is longitudinally displaceable in the direction of its axis of rotation x - x by suitable displacement means (not shown), so as to vary the position of the cams 11 and 12 relative to the fulcrum of the lever 18.
A helical valve spring 21 is received over the valve stem 3 and within the valve bucket 5 so as to be compressed between the closed top end of the valve bucket and a first fixed abutment surface 22 of the engine, thereby biasing the valve 1 into a closed position with its head 2 engaged with the valve seat (not shown).
A second helical spring 23 is received over the valve bucket 5 and engages the lower surface of the lever 18 within the rib 19, so that the spring is compressed between the lever 18 and a second fixed abutment surface 24 of the cylinder head 7 in order to bias the lever into engagement with the profile adjusters 15, 16 of the cams 11, 12.
In operation of the described valve arrangement, the camshaft is axially displaced by suitable means (not shown) to adjust the distance between the fulcrum 9, 20 of the lever 18 and the point at which each of the cams 11 and 12 acts on the lever in order to vary the effectiveness of the two cams with respect to the valve 1. With the camshaft 10 in the axial position illustrated in
Figure 1, the cam 12 acts on the lever 18 in line with the fulcrum of the lever, while the cam 11 acts on the lever at a distance from the fulcrum. In this position, the movement of the valve 1 as a result of rotation of the camshaft 10 is determined by the cam 12 and the cam 11 is ineffective.Displacement of the camshaft 10 to the right in Figure 1 will gradually decrease the effectiveness of the cam 12 and increase the effectiveness of cam 11 until cam 11 becomes dominant in an extreme right hand position in which the cam 11 acts on the lever 18 in line with the fulcrum of the lever.
During rotation of the camshaft to effect linear displacement of the valve 1, the valve spring 21 provides a restoring force to return the valve to its closed position, while the lever biasing spring 23 ensures continuous contact between the lever 18 and the profile adjusters 15 and 16 of the cams.
Figure 2 illustrates a second valve arrangement embodying the present invention which is basically similar to the embodiment of Figure 1, but which has a biasing spring 33 disposed between the lever 18 and the top end of the valve bucket 5. In this case, a downwardly depending rib 29 on the underside of the lever 18 is spaced inwardly from the periphery of the lever 18 and the upper end of the spring 23 is received within this rib. Figure 2 also shows profile adjusters 15 and 16 having more pointed heads 15d, 16d than the heads 15a, 15b of the profile adjusters of the first embodiment.
Figure 3 shows a third embodiment of the present invention, in which valve 1 is operated, as in the first and second embodiments, by a pair of cams 11 and 12 mounted on camshaft 10 for rotation and axial movement therewith.
The cams 11 and 12 acts via profile adjusters 15 and 16 on a transmission lever 38 which has a downward extension 39 extending through an aperture in the top wall of the valve bucket 5 into the interior of the valve bucket. The lever 38 is attached to the bucket 5 and pivotally supported thereon by a pivot pin 30 extending therethrough and supported in journals 31 carried by the valve bucket.
In the Figure 3 embodiment, a biasing spring 33 for the lever is compressed between the lever extension 39 and the fixed abutment surface 22, whereby the spring serves both to bias the lever 38 into engagement with the cams 11 and 12 and to return the valve 1 to its closed position.
Figures It and 5 illustrate a fourth embodiment of the present invention, in which valve 1 is controlled by cams 11 and 12 mounted on camshaft 10 for rotation and axial displacement therewith.
The cams 11 and 12 act on the valve 1 via a pivotable lever 48 pivotally mounted on the valve stem 3 by a fixed support member 40 which is fixedly attached to the top of the valve stem and has a pair of arms 41 and 42 presenting respective cylindrical trunions 43 and 44 which engage in corresponding cylindrical sockets 45 and 46 formed in upstanding flanges 49 and 50 of the lever 48.
A downwardly depending skirt 51 on the lever 48 is provided with an internal annular flange 52. A biasing spring 53 is compressed between annular flange 57 and fixed abutment surface 22, so that the spring 53 serves both as a valve return spring and as a biasing spring to hold the lever 48 in contact with the profile adjusters 15, 16 of the cams 11 and 12.
Figures 6 and 7 illustrate a fifth embodiment of the invention which is similar in principle to the fourth embodiment, in that a transmission lever 68 is pivotally attached to a support member 60 attached to the valve stem. In this case, the fixed support member 60 presents trunnions 63 and 64 engaging in respective journals 65, 66 formed in depending flanges 69 and 70 on the underside of the lever 68. A spring 73 is received over the depending flanges 69, 70 of the lever 68 and is compressed between the underside of the lever 68 and fixed abutment surface 22. In the embodiments of Figures 6 and 7, the profile adjusters 15 and 16 each have only a single bi-furcated arm 15c, 16b.
Claims (11)
1. A valve arrangement comprising a linearly movable valve member displaceable transversely of a fixed abutment surface, an axially movable camshaft, a cam carried by the camshaft for rotational and axial movement therewith, transmission means for converting rotary motion of the cam into linear movement of the valve member and means for axially displacing the camshaft to provide stepless adjustment of the effectiveness with which the rotary motion of the cam is converted into linear movement of the valve member by the transmission means in order to vary a characteristic of the movement of the valve member, in which arrangement the transmission means comprises a support member fixedly attached to the valve member, a lever pivotally mounted on the support member for movement about a fulcrum and a compression spring engaged between the lever and the support member or the fixed abutment surface in order to bias the lever into engagement with the cam, the the cam acting on the lever at a distance from the fulcrum determined by the axial position of the camshaft.
2. A valve arrangement according to claim 1, wherein the lever has a downwardly projecting rib serving to locate an end of the biasing spring which engages the underside of the lever.
3. A valve arrangement according to claim 1, wherein the fulcrum of the lever is defined by a socket formed in the support member and a cooperating projection formed on the lever and freely received in the socket.
4. A valve arrangement according to claim 1, wherein the lever is attached to the support member at the fulcrum so as to be movable therewith in the direction of movement of the valve member.
5. A valve arrangement according to claim 4, wherein
the support member has an upper end wall attached to the
valve member and a downwardly depending skirt which
defines a chamber around a portion of the valve member,
the lever having an extension which projects into the cavity within the skirt of the support member, the -biasing spring being engaged between the lever extension and the fixed abutment surface.
6. A valve arrangement according to claim 4, wherein the lever has a downwardly depending skirt formed with an
internal annular flange and the biasing spring is engaged
between the annular flange and the fixed abutment surface.
7. A valve arrangement according to claim 6, wherein the lever has a pair of upstanding flanges presenting
bearing sockets receiving respective trunnions formed at the ends of a pair of arms extending from the support member attached to the valve member.
8. A valve arrangement according to claim 4, wherein the lever is attached to the support member by means of a pair of trunnions formed on the support member and engaged in journals presented by a pair of downwardly depending flanges formed on the lever.
A valve arrangement according to claim It, wherein
the lever is pivotally mounted on the support member by a
pair of trunnions provided on one of the lever or support member being received in respective bearing sockets on the other of the lever and support member.
10. A valve arrangement substantially as hereinbefore described with reference to Figure 1 or Figure 2 or
Figure 3 or Figures 4 and 5 or Figures 6 and 7 of the accompanying drawings.
11. Any novel feature or combination of features described herein.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB878710544A GB8710544D0 (en) | 1987-06-25 | 1987-06-25 | Variable phase systems |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8815067D0 GB8815067D0 (en) | 1988-08-03 |
| GB2206380A true GB2206380A (en) | 1989-01-05 |
Family
ID=10616818
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB878710544A Pending GB8710544D0 (en) | 1987-06-25 | 1987-06-25 | Variable phase systems |
| GB08815067A Withdrawn GB2206380A (en) | 1987-06-25 | 1988-06-24 | Axially movable camshaft valve gear |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB878710544A Pending GB8710544D0 (en) | 1987-06-25 | 1987-06-25 | Variable phase systems |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB8710544D0 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5052350A (en) * | 1990-11-02 | 1991-10-01 | King Brian T | Device to combine the motions of two camlobes differentially phased |
| CN107208500A (en) * | 2015-01-28 | 2017-09-26 | 伊顿公司 | Axial cam displacement valve assembly with other discrete valve event |
-
1987
- 1987-06-25 GB GB878710544A patent/GB8710544D0/en active Pending
-
1988
- 1988-06-24 GB GB08815067A patent/GB2206380A/en not_active Withdrawn
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5052350A (en) * | 1990-11-02 | 1991-10-01 | King Brian T | Device to combine the motions of two camlobes differentially phased |
| CN107208500A (en) * | 2015-01-28 | 2017-09-26 | 伊顿公司 | Axial cam displacement valve assembly with other discrete valve event |
| US10526928B2 (en) | 2015-01-28 | 2020-01-07 | Eaton Corporation | Axial cam shifting valve assembly with additional discrete valve event |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8710544D0 (en) | 1987-06-25 |
| GB8815067D0 (en) | 1988-08-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |