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
  • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
  • F01L1/02—Valve drive
  • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
  • F01L1/08—Shape of cams
• • 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
  • F01L13/0042—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 with cams being profiled in axial and radial direction
• • 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
  • F01L1/02—Valve drive
  • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
  • F01L1/047—Camshafts
  • F01L2001/0471—Assembled camshafts
  • F01L2001/0473—Composite camshafts, e.g. with cams or cam sleeve being able to move relative to the inner camshaft or a cam adjusting rod

Definitions

• the invention relates to a camshaft for valve-controlled internal combustion engines with two nested shaft elements which are slidably supported one inside the other, first cam elements being connected to the inner shaft element and second cam elements being connected to the outer shaft element, and the outer shaft element being connected to the cam elements of the inner shaft element has assigned wall openings through which pins connecting the cam elements with the inner shaft element pass.
• the cam elements of one shaft element can actuate the intake valves and the cam elements of the other shaft element can actuate the exhaust valves of the cylinders.
• the valve overlap is hereby variable, while the valve opening times cannot be influenced at all.
• the cam elements of one shaft element and cam elements of the other shaft element can also each cause the actuation of inlet valves of the same cylinder.
• the actuation of the exhaust valves of the cylinders can be effected by further cam elements of one of the two shaft elements mentioned or by those of a second camshaft.
• the valve overlap times can be changed with a simultaneous change in the valve opening time of the intake valves. It is known that a slight overlap of the valve opening phases of exhaust and intake valves due to dynamic gas exchange influences is useful in internal combustion engines in the area of partial load and low speeds, while a significant overlap is advantageous especially in the area of higher loads.
• a camshaft of this type is known from DE 36 24 827 AI.
• the cam elements assigned to the inner shaft element slide with a cylindrical bore on the outer shaft element, which has a circumferential slot opposite the cam elevation, through which a single radial fastening pin passes, which connects the cam element to the assigned inner shaft element.
• the object of the invention is to provide a camshaft of the type mentioned at the outset, in which there is a secure and accurate connection between the inner shaft element and the associated cams.
• the solution to this is that the pins connecting a first cam element to the inner wall element penetrate the outer shaft element in two radially opposite wall openings. It is therefore essential that the first cam elements designed with a cylindrical inner bore are double-pinned to the inner shaft element at mutually opposite points in order to reliably prevent deformation of the cam and the shaft body.
• the pins are inserted from the base circle of the cams and extend into the cam elevation. These can be two shorter pins of different diameters or a single continuous pin.
• the cams have an extension sleeve at least on one side, which is penetrated by a single pin.
• a press fit is preferably provided for the pins.
• the insertion and shrinking of supercooled pins can be used.
• the shaft elements are slidably guided and supported at least at their ends or at all bearing points.
• a suitable connecting method for the external shaft element with the assigned cams consists in an internal expansion of the tubular body in sections in the area of the cam elements, in particular with hydraulic pressure generation. There is also one from the inside of the pipe performed laser welding possible with the aid of a deflecting mirror, as is known as such.
• the camshaft is manufactured in such a way that all the cams are pushed onto the outer shaft element in the required order, then the individual pipe sections of the outer element are expanded within the second cam to fix them. Instead of hydraulic expansion, shrinking, welding or soldering can also take place. Then the first cam elements are pinned to the inner shaft element inserted for this purpose, the press fit being able to be produced by the shrinking-in mentioned above.
• an adjusting device is to be provided at one end of the shaft elements, which is intended to change the position of the two shaft elements relative to one another with the aim of changing the timing of the two groups of cam elements relative to one another.
• this can take the form of a relative rotation of the two shaft elements relative to one another, the wall openings in the outer shaft element having to be formed as circumferential slots as a prerequisite, which guide the pins passing through them.
• the cam elements of the shaft element displaceable relative to the valves having to have a spatial shape with an axially variable elevation curve and the wall openings in the outer shaft element as Longitudinal slots must be formed which guide the pins.
• a window larger than the pin diameter can be provided.
• Figure 1 shows a first embodiment of a camshaft in longitudinal section.
• Figure 2 shows a second embodiment of a camshaft in longitudinal section.
• FIG. 3 shows a camshaft according to FIG. 1 in cross section through a cam.
• Figure 4 shows three versions of wall openings in view.
• FIGS. 1 and 2 each show an inner tubular shaft element 1 and an outer shaft element 2, which can be rotated and / or displaced relative to one another by means of an adjusting device (not shown).
• the outer shaft element 2 carries cam elements 8 fixed directly thereon, between which cam elements 7 which are adjustable relative to the outer shaft element 2 and which are connected to the inner shaft element 1 are pushed.
• the nested shaft elements are supported radially at the ends via bearing sleeves 10, 11.
• a pair of cam elements 7, 8 is surrounded by bearings 6.
• Axial stops 3 fixed on the external shaft element 2 support the shaft in relation to the camshaft bearings 6.
• In the outer shaft element 2 are opposite wall openings 5, which are penetrated by pins 4, which are fixed in the inner shaft element 1 and fix the cam elements 7 thereon.
• the cam elements 7 are shown with axially variable elevation curves.
• a pin 4 enters the cam elements 7 in the base circle and extends into the cam elevation on the opposite side.
• the cam elements 7 have lugs 9, which are penetrated by a pin 4 opposite each other.
• FIG. 3 shows in detail a cam element 7 which has a blind bore 13 which extends into the cam elevation 12 and into which a pin 4 is inserted, which is at the same time press-fit into the bores of the internal shaft element 1.
• wall openings 5 can be seen in the outer shaft element 2, which are large compared to the pin diameter and allow at least one angular adjustment of the shaft elements relative to one another.
• the insertion opening 14 for the pin 4 lies in a non-load-bearing central circumferential groove 15 of the cam element 7 provided on the base circle in order to prevent damage to the valve disk.
• FIG. 4 shows wall openings 5 in the form of a circumferential slot 5a, a longitudinal slot 5b and a window 5c with which angular and / or longitudinal adjustments of the shaft elements with respect to one another can be represented.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Valve Device For Special Equipments (AREA)
• Valve-Gear Or Valve Arrangements (AREA)

Applications Claiming Priority (4)

Publications (1)

Family

ID=25888395

Family Applications (1)

Country Status (2)

Cited By (2)

Families Citing this family (25)

Citations (2)

• 1989
  • 1989-12-30 DE DE19893943426 patent/DE3943426C1/de not_active Expired - Lifetime
• 1990
  • 1990-11-29 WO PCT/EP1990/002048 patent/WO1991010047A1/de unknown

Patent Citations (2)

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