CN101153549A

CN101153549A - Engine tubular camshaft assembly with multi-lift cam sets and method

Info

Publication number: CN101153549A
Application number: CNA2007101821180A
Authority: CN
Inventors: M·R·克莱恩; D·L·奥奈尔
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2006-09-13
Filing date: 2007-09-13
Publication date: 2008-04-02
Also published as: US20080060594A1; DE102007043169A1

Abstract

An engine camshaft assembly includes a hollow tubular shaft mounting a plurality of separate cam sets, each including multiple camps. Each cam includes an outer cam surface bounded by opposite parallel sides and including an axial opening extending through said sides. Each cam set includes at least two associated cams positioned in side-by-side relation with their openings axially aligned. A shoulder protruding from a side of one of the cam engages an adjacent side of another associated cam, thus maintaining the sides of the associated cams in fixed parallel relation. The tubular shaft extends through the cam openings and supports the cam sets on a common rotational axis. During assembly, the shaft is expanded into engagement with the openings so that the cam sets are retained in fixed axial and angular relation on the shaft.

Description

Engine tubular camshaft assembly and assembly method thereof with multi-lift cam sets

Technical field

[0001] the present invention relates to be used for the assembling camshaft of internal-combustion engine, relate in particular to by prolong the camshaft that hollow tubular shaft is assembled between cam that is associated and miscellaneous part.In a preferred embodiment, the present invention relates under the different operating conditionss of motor, to be used to open the camshaft of two-stage valve tappet of the optional setting with optionally low or high valve lift setting or full lift and zero lift of engine valve.

Background technique

[0002] as known in the art is to become the preposition cam by the prolongation with hollow tubular shaft, and axle journal and miscellaneous part are made the engine cam shaft assembly.Each cylinder comprises two intake valves and two exhaust valves in the existing engine design, and this makes a plurality of valve executive modules in engine cylinder cap need the space.Changing this existing plan of intake valve or exhaust valve lift needs to use the cam of different geometries, and this may produce with other hydraulic pressure converting member and influence each other, so that the control geometrical shape is to the influence of valve motion.Two or three cams of each valve all need be carried out this control.The extra cam and the limitation of complexity of miscellaneous part free space, and need minimized size and in the split hair control of camshaft characteristic location.

Summary of the invention

[0003] characteristics provided by the invention are to improve assembling and are fixed on for example cam, the horizontal spacing between separation sleeve and the miscellaneous part and the control of up rightness of different parts that can expand on the tubular shafts.By increasing the separation sleeve and the cam shaft shoulder, very Jin Cou size Control can obtain these characteristics.The two-stage camshaft design necessitates this control, thereby suppresses the too high tolerance of horizontal spacing and vertical property.The design of cam follower needs three actuator's three cams of contact to control the lift of each valve.Two slip driven members contact with outside cam, and a rolling driven member contacts with the steel center cams.These accurate mechanisms are the location accurately, must be installed on the point of contact of cam, so that system's normally operation under high speed.

[0004] the present invention comprises a steel center cams and two cast iron end cams for each valve provides cam gear.Flank of cam is at interval accurate to each other, and keeps vertical by the use of the shaft shoulder on the center cams.This shaft shoulder extends to end cams and engages to keep the close tolerance of horizontal spacing between them.Provide the separation sleeve that can be used as supporting sleeve so that laterally accurately cam gear is being spaced apart from each other.The design of cam assembly allows to use different cam materials, or is applied to the material of miscellaneous part on the camshaft, and with high-precision horizontal spacing and minimum manufacture difficulty assembling use each parts in cam gear and other elements.Use and supporting sleeve precision with Hardened Steel cam of the spacing shaft shoulder are cut to length and vertical property, just can obtain the required accurate dimensions characteristic of cam assembly that can move in the existing confined space in some new engine design.

[0005] these and other characteristics and advantage of the present invention will become from the explanation of specific embodiment of the present invention hereinafter and accompanying drawing and fully understand more.

Description of drawings

[0006] Fig. 1 is the part of a cam assembly, it has a pair of three unit cam gears that separate, described cam gear by a supporting axle separation sleeve separately, and be fixed by the expansion of tubular bulb in the parts, the tubular bulb expansion is by its outward edge of middle bore expansion that a steel ball or same element mechanically pass tubular axis it to be engaged with the parts that adhere to.

[0007] Fig. 2 is the sectional view of Fig. 1 cam shaft assembly, illustrates the cam of the cam gear of the cam assembly shown in the pie graph 1, isolates pipe box and hollow tubular shaft.

Embodiment

[0008] in detail with reference to the accompanying drawings, the cam assembly that digital 10 ordinary representations form according to example of the present invention, it has spin axis 11.This cam assembly comprises an axially extended hollow tubular shaft 12, a plurality of cam gears 14, each cam gear comprises an inboard or center cams 16 and two ends or outside cam 18 and an isolation pipe box or supporting sleeves 20 of laterally separating cam gears 14 and together rotating with tubular axis 12 along axis 11.

[0009] each

cam

16,18 comprises an axial bore 22 that extends through the relative parallel side of cam 24.Similar axial bore 26 extends through axle sleeve 20.Center or inboard cam 16 comprise the annular shaft shoulder 28 that extends from the relative parallel side 24 of cam, and this annular shaft shoulder has the end face 30 through accurate machining, and is connected mutually with the inner side surface 24 of the end cams 18 that is associated.In assembly, end face 30 operate together of the parallel side 24 of end cams and the center cams shaft shoulder are to keep the parallelism between the

cam

16,18 of forming each cam gear 14.The outer side surface 24 of the cam gear that the parallel end faces 32 of axle sleeve 20 is same and adjacent is connected mutually, to keep the parallel relation of the cam gear cam that is associated.

Cam gear and axle sleeve are fixed on the hollow tubular shaft 12 by hollow tubular shaft being inserted their

holes

22,26 separately, and keep the vertical joint between the build-up member when hollow tubular shaft is passed hollow hole of centre 34 mechanical expansions of hollow tubular shaft by excessive ball.This process is expanded with the hole of different parts tube exterior and is engaged, cam gear and axle sleeve are locked on the position of hollow tubular shaft 12, so

cam

16,18 and axle sleeve 20 all maintain the predetermined horizontal and angular dependence of setting up before the mechanical expansion step.In cam gear 14, the side of cam is the keeping parallelism relation all, and this parallel relation is to have predetermined accurate dimensions between the flank of cam that is associated at interval in cam gear.

As shown in the figure, the outer surface 38 of end cams 18 has the maximum centrifugal rate, is to reach height or maximum lift in order to drive relevant engine valve.The outer surface 36 of center cams 16 has the eccentricity of minimizing, is to reach a low lift in order to drive relevant engine valve.

In typical embodiment, center cams 16 can be made by Hardened Steel, and end cams 18 can be made by gray cast iron or other suitable materials, is used for the sliding contact cam follower.Similarly, in center cams, the Hardened Steel material is suitable for traditional roller tappet.Axle sleeve or separation sleeve 20 can be made with gray cast iron or Hardened Steel, this depend on they be used for bearing 12 and of the present invention other must parts.Tubular shafts 12 can be formed by the mild steel that is applicable to the ball process of expansion.In order to keep center cams and the end cams accurate dimension of

outer surface

36,38 separately, it is after camshaft parts forms this expansion step of cam assembly that these surfaces reach final size.

Except the ball process of expansion, other forms of pipe expansion can be applied to the present invention.These forms can comprise the mechanical type of expansion, except the form of ball, also have the mode of hydraulic pressure or other pressure to make the pipe expansion.

It should be understood that those materials and step except mentioning especially about accompanying drawing embodiment, different parts and concrete steps can adopt other materials and method step in the cam assembly of the present invention.Various feature of the present invention comprises the parallel surface and the shaft shoulder of cam gear parts, axle sleeve or separation sleeve, the distance between shafts of the preprocessing of the shaft shoulder and axle sleeve regulation, and the last polishing of the

cam face

36,38 of the cam gear of build-up member after to the axle, all these are combined provides a cam assembly that accurately forms, have minimal tolerance and change, in taking motor, also can drive the driven member of the tight isolation of two-stage or commutation valve tappet during the space of cylinder head or other minimum flows in camshaft mounting point.

Although invention has been described with reference to concrete preferred embodiment, being understandable that in the spirit and scope of described principle of the present invention to have a lot of versions.Therefore, this means that the present invention should not be subjected to the restriction of disclosed embodiment, and it have all scopes that following claim allows.

Claims

1. engine cam shaft assembly that can rotate around running shaft comprises:

A hollow tubular shaft and a plurality of independently cam gear, each described cam gear comprises a plurality of cams;

Each described cam comprises the outer cam surface and the axial bore that passes described side that are limited by relative parallel side;

Each described cam gear comprises at least two also associated cam of registration, align along axial direction in the hole of described cam, the shaft shoulder from a side extending projection of one of them described cam, engaging of the cam that the described shaft shoulder is associated with another in abutting connection with the side, thus parallel relation fixed between the flank of cam that has guaranteed to be associated;

Described tubular axis extends through described cam hole and supports described cam gear with common shaft, and described tubular axis expansion is to engage with described cam hole so that the axial and angular dependence that described cam gear is maintained fixed on described tubular axis.

2. assembly as claimed in claim 1 is characterized in that described outer cam surface comes fine finishing by polishing after described cam gear is assembled on the described hollow tubular shaft.

3. assembly as claimed in claim 1 also is included in camshaft supporting axle journal that at least optionally forms between the pair of cams device and the supporting surface that forms by polishing after the camshaft assembling is finished.

4. assembly as claimed in claim 3 is characterized in that forming described bearing journal on the steel support sleeve of fixing by the expansion of the described tubular axis in the lining.

5. assembly as claimed in claim 4, it is characterized in that described support sleeve comprise with described cam gear in the smooth parallel end faces of engage sides of described adjacent cam, described smooth parallel end faces is auxiliary keeps parallel relation between the described cam in the described cam gear of described cam assembly.

6. assembly as claimed in claim 1, at least some comprise that the cam with different eccentricities is so that drive the two-stage type valve tappet to it is characterized in that described cam gear.

7. assembly as claimed in claim 1 also comprises the cam gear that drives the two-stage type valve tappet, and each described cam gear is included in the low lift center cams that is provided with between two high lift end cams.

8. assembly as claimed in claim 7 it is characterized in that described center cams is made by Hardened Steel so that the driving rolls driven member, and end cams is made by cast iron so that drive the sliding cam driven member.

9. assembly as claimed in claim 8 is characterized in that described center cams has the shaft shoulder that extends from bi-side, and engages with the side of the end cams that is associated, so that provide predetermined space each other in outer cam surface.