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AssigneeIveco Fiat S.p.A.
InventorsPietro Bianchi, Dragoljub Milanovic
Estimating the term…
A chain transmission device for controlling the timing system of an internal combustion engine with two overhead camshafts, and having a first chain transmission from the drive shaft to an intermediate shaft, and a second chain transmission from the intermediate shaft to both the camshafts; and wherein the first transmission defines a step-down transmission ratio between the drive shaft and the intermediate shaft; the second transmission defines a step-down transmission ratio between the intermediate shaft and the camshafts; the chain of the second transmission has a pitch smaller than the pitch of the chain of the first transmission; and the intermediate shaft is defined by the drive shaft of a fuel pump of the engine.
A chain transmission device (1) for controlling a timing system of an internal combustion engine (2) with two overhead camshafts (4, 4′), and comprising a first chain transmission (7) from a drive shaft (3) to an intermediate shaft (5), said first chain transmission (7) including a drive sprocket (10) on said drive shaft (3), a driven sprocket (11) on said intermediate shaft (5), and a first chain (12) meshing with and trained around said drive sprocket (10) and said driven sprocket (11);
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Valve-gear or valve arrangements, e.g. lift-valve gear: valve drive
Valve drive: chain drive
Gearings for conveying rotary motion by endless flexible members: with chains
Finally actuated members, e.g. constructional details thereof: two or more finally actuated members
Term ended 22 Dec 2020 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
The present invention relates to a chain transmission device for controlling the timing system of an internal combustion engine with two overhead camshafts.
Single-chain control of both the camshafts of internal combustion engines of the above type poses serious problems in terms of size.
That is, the distance between the axes of the camshafts is a design feature which depends on the valve arrangement, and, for reasons of size, should be as small as possible.
The FIGURE shows schematically the chain transmission device of the present invention.
Number 1 in the accompanying drawing indicates a chain transmission device for controlling the timing system of an internal combustion engine, in particular a diesel engine, 2.
Engine 2 comprises a drive shaft 3 of axis A and angular speed ωM; and two overhead camshafts 4,4′ of speed ωC=½ωM and having respective axes B, C parallel to each other and to axis A and separated by a distance i.
Engine 2 also comprises an intermediate shaft 5 for driving a high-pressure fuel pump 6 forming part of a storage injection system (not shown). Using a storage system allows a certain amount of freedom in selection of the angular speed (ωI) of pump 6, i.e. of intermediate shaft 5. In such a system, the speed of the pump is preferably the same as that of the drive shaft, or lower according to the equation N/2*nP, where N is a whole number, and nP the number of pumping members (normally 3 or 4) of the pump. Such a relationship ensures a whole number of pumping strokes in each engine cycle (two revolutions of the drive shaft), and hence a known constant phase relationship between variations in the feed pressure of the injectors and the points in the engine cycle—predetermined and the same for each cycle—at which pressure is determined by the electronic injection control system (as is known, in storage systems, the amount of fuel injected is controlled electronically by varying the opening time of the pins).