DE2634916A1 - REVERSIBLE PISTON ENGINE - Google Patents

Description

Maschinenfabrik Augsburg-Nürnberg Aktiengesellschaft 8900 Augsburg, Stadtbachstrasse 1

P. B. 2884/1298 Augsburg, July 27, 1976

Reversible reciprocating internal combustion engine

The invention relates to a reversible reciprocating internal combustion engine, in particular for driving ships, with control cams arranged on a displaceable camshaft, which in the reversing direction each have increasing contact surfaces for the tappets which interact with the control cams.

In arrangements of this type, two control cams are usually assigned to each tappet, one of which is for use with Clockwise rotation and the other is designed for use in counter-clockwise rotation, so that a shift occurs with every change of direction of rotation the control cam must take place in relation to the associated tappet. The cams are usually mirror images of TDC folded down. It therefore often happens that the full cam height has to be overcome when reversing. To prevent a Jamming of the plunger has therefore already been done by

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that the control cam with increasing contact surfaces in the reversing direction were provided.

As a rule, however, an approximately linear rise in the contour was provided. The change accordingly The forces of action and the work done also change direction linearly via the path of change. This results in a non-uniform Distribution of the forces over the path, in particular with regard to the reversing force that occurs in known arrangements at the end of the reversing process increases to more than six times its original size. However, the maximum size of the reversing force is decisive for the design of the reversing and the reversing aid. The known arrangements therefore require due to the linear The increase in the contact surfaces is a relatively massive and therefore expensive and, moreover, subject to a great inertia construction.

Starting from this, it is the object of the present invention, while avoiding the disadvantages of the known arrangements with simple and therefore highly cost-effective means a control cam to create that requires relatively small reversing forces, which also remain essentially constant over the reversing path.

This object is achieved surprisingly according to the invention simply by a non-linear increase in the contact surfaces in the reversing direction with at least two branches, one lower branch of relatively high slope, which extends up to about half the cam height, and another, adjoining this Branch with a lower slope, which extends to the full cam height. The"

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This solution is based on the knowledge that the force exerted by the plunger on the contact surface and thus the friction or. Slip ratios very much from the other hand on the Depend plunger acting spring force, which, as is known, increases with the displacement. In the area of small spring forces, that That is to say, at the beginning of the shift, relatively high gradients are therefore still provided according to the invention, in the end region of the Displacement, on the other hand, the slope should be reduced accordingly to compensate for the strongly increased spring forces. This results in a certain equalization in an advantageous manner and reduction of the necessary reversing forces.

A particularly extensive equalization and reduction of the necessary reversing forces can be achieved according to a particularly preferred embodiment of the invention in a simple manner thereby achieve that the envelope curve of the rise of the contact surfaces in the circumferential direction indicated at the end of the description Equation follows. Particularly preferred ratios can evidently be achieved in that the contour of the rise of the contact surfaces itself follows this equation. These measures allow the necessary reversing forces to be reduced by up to 50% "of the forces required in comparable known arrangements. As the reversing force via the over-steering path is practical remains completely constant, there are advantageously no jerky movements of the control shaft, which in the known arrangements have led to heavy use of the bearings etc. In addition, this results during the reversal process a reduction in the pressure between the ram and the cam

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ken and thus a long service life in an advantageous manner. In addition, in the range of maximum delivery pressures of the fuel pump, an increase in the load-bearing surface and thus also in A reduction in surface pressure can be achieved in this area. With the help of templates or through the use of computer-controlled systems Machine tools can also keep the manufacturing effort within reasonable limits.

The present invention therefore allows overall a lighter and therefore more cost-effective dimensioning of the entire reversing device, in addition to the low production costs the low running operating costs cannot be disregarded either. Those achievable with the present invention Advantages can therefore be seen in particular in their economic efficiency.

Further features and advantages of the invention emerge from the following description of an exemplary embodiment the drawing in connection with the claims.

Show here

Figure 1 a pair of cams for controlling a

Valve and

Figure 2 shows a preferred contour of the contact surface

of a reversing cam.

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In FIG. 1, 1 is, for example, an exhaust valve of a four-stroke diesel engine denotes, which can be pivoted with a closing spring 2 and one at 3 for effecting the valve movement suspendable rocker arm 4 cooperates. The rocker arm 4 is on the opposite side of the valve 1 with a Control cam 5 or 6 cooperating push rod 7 connected, which in the illustrated embodiment on their cam side The end is provided with a plunger roller 8. The cams and 6 are circumferentially offset from one another on the indicated at 9, displaceable control shaft 9 arranged. An arrangement of the type described above is in the area of each Valve and every injection pump. As a rule, there is a common control shaft for each cylinder bank intended.

When the internal combustion engine is running clockwise, for example, the control cam 5 shown on the right in the illustrated embodiment, the control cam 6 shown on the left can be used for counter-clockwise rotation. The tappet roller 8 in each case rolls on the running surface 10 or 11 of the cams 5 and 6 respectively. When changing the direction of rotation Therefore, the control shaft 9 must be moved according to the distance between the running surfaces 10 and 11. In the illustrated embodiment, the control shaft 9 is indicated in an intermediate position, in which the control shaft is shifted from right to left and the tappet roller 8 from the area of the lowest elevation of the cam 6 reaches the area of the highest elevation of the cam 5. The cams 5 and 6 are used to overcome such height differences

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each provided with contact surfaces 12 and 13 increasing in the reversing direction. The necessary to move the control shaft 9 Force obviously depends on the pressure between the plunger roller 8 and the contact surface 12 and thus on the by the Spring 2 exerted force and ultimately on the inclination of the contour of the contact surface 12. The spring force increases with " The spring travel increases, so it is still small in the lower area of the contact surface 12 and reaches the area in the upper area the highest cam lobe, its maximum.

As can be seen from FIG. 2, the contact surfaces 12 and 13, in contrast to the known solutions, are therefore not provided with a provided linear rise, but rise non-linearly, wherein at least two branches 14 and 15 can be provided. Of the in the illustrated embodiment, designated with 14, the lower branch has a relatively high slope and extends up to about half the cam height, the adjoining further branch 15, which extends up to the full cam height, points in contrast a much smaller slope. This ensures that when the control shaft is moved, the spring force in the increases relatively quickly in the lower area, while in the upper area it increases relatively slowly. Accordingly, there is opposite the known arrangements a certain equalization and reduction of the necessary reversing force. A reduction the necessary reversing force of up to 50% compared to the known solutions can be expected if the envelope curve indicated at 16 the branches 14 and 15 of the equation I given at the end of the description follows. Another embodiment can be

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stand that the contour of the rise of the contact surfaces 12 or 13 of the above equation follows. In this embodiment, the reversing force remains in an advantageous manner over the entire Reversal path constant. The advantage of the embodiment shown can be seen in the particularly simple production.

A particularly preferred exemplary embodiment is introductory the invention explained in more detail * without, however, hereby a Restriction should be connected »Rather, the expert, as indicated, a number of ways are available to the general idea of the invention, t & e reversing force constant to Keep in mind to reduce the circumstances of the individual case adapt.

C Happy J?
where x *

^ r «Änsiäeg. & t radial direction

* ίϊΟ / Jo »^ eibungskoefScient

üeibuiigswiQkel
Q

κ:

Spring constant

Displacement force in the axial direction

Claims (3)

Expectations 1. j Reversible reciprocating internal combustion engine, in particular for propulsion of ships, with control cams arranged on a sliding camshaft, which operate in the reversing direction each have increasing contact surfaces for the tappets which interact with the control cams, marked by a non-linear increase in the contact surfaces (12, 13) in the reversing direction with at least two branches (14, 15), a lower branch (14) relatively high slope, which extends to about half the cam height, and an adjoining branch (15) with a lower slope, which extends up to the full cam height. 2. Reversible reciprocating internal combustion engine according to claim 1, characterized in that the envelope curve (16) of the branches (14, 15) of the contact surfaces (12, 13) in the reversing direction of equation I follows. 3. Reversible reciprocating internal combustion engine according to claim 1, characterized in that the contour of the rise of the contact surfaces (12, 13) in the reversing direction of equation I follows. 709886/0169