JPS6118008B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a switchably controllable reciprocating piston internal combustion engine for driving, for example, a ship, which comprises a control cam mounted on a longitudinally movable camshaft. , the control cams are of the type in which the control cams have an inclined surface for the tappet cooperating with the control cams, each inclined in the switching control direction.

BACKGROUND OF THE INVENTION In devices of this type, each tappet is generally assigned two control cams, one for clockwise rotation and the other for counterclockwise rotation. It is therefore necessary to move the control cam relative to the associated tappet at each rotational alternation. The control cams are generally arranged mirror-symmetrically with respect to top dead center. Therefore, it often happens that the entire cam lift has to be overcome during the switching control. In order to prevent tappet binding, it has already been possible to provide the control cam with an inclined surface which is inclined in the switching control direction.

Problems to be Solved by the Invention However, in this case, generally a substantially linear slope is proposed when viewed in cross section of the slope. Correspondingly, the motion force and working force during switching control become linear over the entire switching control distance. This results in an uneven distribution of forces over this distance, in particular an uneven distribution of switching control forces. Thus, in the known device, the switching control force increases by more than six times its starting value towards the end of the switching control process. Since the maximum value of the switching control force is the standard for the design of the switching control and the switching control device, the known device has a linearly inclined slope, so it has a relatively large mass, is therefore expensive, and has a large inertial force. equipment is required.

The object of the invention is to obviate the disadvantages of the known devices and to achieve the same by simple and therefore as inexpensive means as possible.
The object of the present invention is to provide a control cam which requires only a relatively small switching force and moreover an almost constant switching force over the entire switching control distance.

Means for Solving the Problems The gist of the present invention for solving the above problems is that the inclined surface extends non-linearly as a whole, has a relatively steep slope, and extends to approximately the front half of the cam lift. It has at least two sections, including a lower section and an upper section that extends with a gentle slope up to the full cam lift. The basic idea of the invention is that the force acting from the tappet on the inclined surface, and thus the friction ratio or slip ratio, is, on the other hand, significantly dependent on the spring force acting on the tappet and increasing with the travel distance. According to the invention, therefore, the slope is relatively steep while the spring force is low, in other words at the beginning of the travel, whereas in the end of the travel the spring force increases significantly in this range. The slope is correspondingly gentle to compensate for this. This advantageously equalizes and reduces the required switching control forces.

In order to more effectively equalize and reduce the required switching control force, in one embodiment of the present invention, the lower section and the upper section of the inclined surface in the switching control direction have a polygonal line shape having an envelope curve that satisfies the following equation. is formed.

In the above formula, x = travel distance in switching control direction, y = radial inclination, μ = fgρo = friction coefficient, ρo = friction angle, a = C/K C = spring constant, K = C・yy′+μ/ 1-μy'=g(y, y') = axial displacement force. In this case, it goes without saying that each section is smoothly connected by a curved line. It is particularly advantageous if the slope contour of the slope itself satisfies this formula. By this measure, the switching control forces are reduced by up to 50% compared to the official system.

Embodiments Next, the present invention will be specifically explained with reference to illustrated embodiments.

In FIG. 1, reference numeral 1 designates an outlet valve of, for example, a four-stroke diesel engine, which outlet valve 1 cooperates with a valve spring 2 and with a rocker arm 4 pivotable about reference numeral 3 for the valve movement. are doing.
The rocking arm 4 is connected to a control cam 5 on the side opposite the outlet valve 1.
or 6, is connected to a tappet rod 7 which in the illustrated embodiment is provided with a tappet roller 8 at its cam end. The control cams 5, 6 are arranged on a longitudinally movable control shaft 9, angularly offset from each other in the circumferential direction. An arrangement of this type is necessary within each valve as well as each injection pump. In this case, one common control shaft is generally provided for each cylinder row.

For example, in this embodiment, the control cam 5 shown on the right side of the drawing is used when the internal combustion engine rotates to the right, and the control cam 6 on the left side is used when the internal combustion engine rotates to the left. Tappet roller 8 is connected to cam surface 10 of control cam 5 or 6.
Or roll along 11. Therefore, when changing the direction of rotation, the control shaft 9 must be moved in the longitudinal direction in accordance with the distance between the cam surfaces 10 and 11. In the drawing, the control shaft 9 is shown in an intermediate position during its movement from right to left, and the tape roller 8 attempts to reach from the slight elevation range of the control cam 6 to the maximum elevation range of the control cam 5. This is the place to do it. In order to overcome such height differences, the control cams 5, 6 are provided with inclined surfaces 12 and 13, respectively, which are inclined in the switching control direction. Control axis 9
The force required to move the tape roller 8 and the inclined surface 1 is
2 and thus to the force exerted by the valve spring 2, which is ultimately related to the slope of the contour of the inclined surface 12. The spring force increases as the degree of compression of the spring increases. The spring force is therefore still small in the lower region of the ramp 12, but reaches a maximum in the upper region, ie in the most elevated region of the control cam.

As can be seen in FIG. 2, the inclined surface 12 does not have a linear inclination, as in the known type, but is inclined non-linearly, in which case at least the lower section 1
Two sections can be provided: 4 and an upper section 15.

In the embodiment shown in solid lines in FIG. 2, the ramps include a straight lower section 14 with a relatively steep slope extending up to half the cam lift and a straight upper section 14 with a gentle slope extending up to the full cam lift. 15 and a smooth curved portion connecting the lower section 14.
and the envelope curve of the polygonal line consisting of the upper section 15 is It is represented by a curve 16 that satisfies the equation. In the formula, x = travel distance in switching control direction y = radial slope μ = fgρo = friction coefficient ρo = friction angle a = C/K C = spring constant K = C・yy'+μ/1-μy'=g (y, y') = axial moving force.

In another embodiment of the present invention, the entire contour of the inclined surface 12 itself is represented by a curve 16 that satisfies the above equation, as shown by the dashed line in FIG. In this embodiment, the switching control force is advantageously constant over the entire switching control distance. The advantage of this embodiment is that it is particularly simple to manufacture.

According to the invention, during the longitudinal movement of the control shaft 9, the spring force increases relatively quickly in the lower section and relatively gradually in the upper section. This achieves a uniformity and reduction of the required switching control forces compared to known devices. The required switching control force is reduced by as much as 50% compared to the known example.

The invention is not limited to the illustrated embodiment.

Advantages of the invention According to the invention, the switching control force is practically constant over the entire switching control distance, so that impulsive movements of the control shaft, etc., which in known devices would lead to significant loading of the bearings, are avoided. is avoided. Furthermore, the pressure between the tappet and the control cam during the switching control process is reduced, thereby increasing the service life. Furthermore, within the range of the maximum discharge pressure of the fuel pump, an increase in the supporting surface and thus a reduction in the surface pressure within this range is obtained. By using templates or computer-controlled machine tools, the manufacturing costs can also be kept within economic limits.

The invention therefore allows for a lightweight and therefore inexpensive design of the entire switching control device as a whole. Moreover, in addition to the low manufacturing cost, the operating cost can also be reduced. The advantages obtained by the invention are therefore primarily economic.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a pair of control cams for controlling a valve according to an embodiment of the present invention, and FIG.
FIG. 6 is a diagram showing the contour of the inclined surface of the control cam according to the embodiment. 1... Outlet valve, 2... Valve spring, 3... Code, 4
... Swing arm, 5, 6 ... Control cam, 7 ... Tappet rod, 8 ... Tappet roller, 9 ... Control axis, 1
0,11...Cam surface, 12,13...Slanted surface, 1
4, 15... Division, 16... Curve.

Claims (1)

[Scope of Claims] 1. A reciprocating piston internal combustion engine with switchable control, comprising control cams mounted on a longitudinally movable camshaft, each of which has a control cam tilted in the switching control direction. In those types with inclined surfaces for the tappets cooperating with the cam, said inclined surfaces 1, 2, 13 extend non-linearly as a whole and have a relatively steep inclination that substantially extends to the cam. Switchably controllable reciprocating piston characterized in that it has at least two sections, including a lower section 14 extending up to the front half of the lift and an upper section 15 extending with a gentle slope up to the full cam lift. Internal combustion engine. 2. at least two sections including the lower section 14 and the upper section 15 of the inclined surfaces 12, 13 in the switching control direction It is formed in a polygonal line shape having an envelope as a curve that satisfies the formula, and each section is smoothly connected by the curve, and in the above formula, x = travel distance in the switching control direction, y = radial direction slope, μ=fgρo=friction coefficient, ρo=friction angle, a=C/K C=spring constant, K=C・yy′+μ/1−μy′=g(y,y′)=axial movement 2. A switchable reciprocating piston internal combustion engine according to claim 1, wherein the internal combustion engine is a switchably controllable reciprocating piston internal combustion engine. 3. The whole of at least two sections including the lower section 14 and the upper section 15, It consists of a curve that satisfies the equation, where x = travel distance in the switching control direction, y = radial slope, μ = fgρo = friction coefficient, ρo = friction angle, a = C/K, C = spring constant, The switchable reciprocating piston internal combustion engine according to claim 1, wherein K=C·yy′+μ/1−μy′=g(y,y′)=axial moving force.