JPS587818B2 - Stepwise rotatable piston for reciprocating internal combustion engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stepwise rotatable piston for a reciprocating internal combustion engine, the piston being mounted on a connecting rod for rotation about its longitudinal axis, the piston having two
a stepping member having two friction surfaces adapted to pivot reciprocally about the longitudinal axis of the piston in response to pivoting of the connecting rod, one friction surface having a corresponding friction surface on the piston; the other friction surface cooperates with a corresponding friction surface of a pushing member adapted to move along a longitudinal axis within the piston, the operative connection between the stepping member and the piston being connected to the pushing member and the stepping member. caused by the inertial force of

A conventional piston of a reciprocating internal combustion engine moves only in the direction of its longitudinal axis, so that a connecting rod connected to the piston at one end pivots about an axis perpendicular to the longitudinal axis of the piston.

In such a piston, a certain part of the piston's sliding surface always moves in contact with the same part of the cylinder wall surface with each stroke, so the wear of the piston and/or the surrounding cylinder wall surface is reduced from the circumferential direction of the piston. It has the disadvantage of being uneven in appearance.

To prevent this phenomenon, it is known to rotate the piston about its longitudinal axis in stages.

Due to this rotation for each stroke, a certain portion of the sliding surface of the piston also moves in contact with other parts of the cylinder wall.

The function of the known stepwise rotatable piston according to British Patent No. 1,169,326 is as follows.

Referring to FIG. 4, as the piston 41 moves from its top dead center and descends, the pushing member 45 and stepping member 44 occupy the highest position within the piston 41 due to inertia.

As a result, the friction surface of stepping member 44 is disengaged from the associated friction surfaces of pusher member 45 and ring 43 and, therefore, pivoting of stepping member 44 has no effect on piston 41.

This pivoting is effected via pin 46 by pivoting the connecting rod 42 down one-half stroke from top dead center.

At this point, stepping member 44 has moved piston 4
Begin the pivoting motion used to rotate 1.

The speed of this pivot increases from said position (one-half stroke down from top dead center) to bottom dead center and then decreases until one half stroke up from bottom dead center. .

As a result of their inertia, the pushing member 45 and the stepping member 44 begin to move within the piston 41 towards the friction surface of the ring 43, since the downward movement of the piston 41 is only one-half stroke from top dead center. This is because the vehicle decelerates from the lowered position.

The piston 41 includes a stepping member 44 and a ring 4.
The stepping member 44 rotates due to the frictional engagement of the pressing member 45 which is pressed against the stepping member 3 by inertial force.

The above frictional engagement means that the upward movement of the piston is 2 times from the bottom dead center.
Since it is accelerated while going up by 1/2 stroke, theoretically it will be maintained from the position where it has descended by 1/2 stroke from top dead center until it passes through bottom dead center and goes up by 1/2 stroke. Ru.

However, since the pivoting speed of the stepping member 44 slows down after the bottom dead center, the rotational drive of the piston 41 is slightly braked while the piston 41 moves up by one-half stroke from the bottom dead center.

The upward movement of the piston decelerates from the one-half stroke position before top dead center to top dead center, so that the pushing member 45 and stepping member 44 are released from engagement with ring 43 due to their inertia. It comes off.

Because of this disengagement, pivoting of stepping member 44 has no effect on the piston from the one-half stroke position before top dead center to top dead center.

Another disadvantage of known pistons is that because the friction surfaces of the stepping members are continuous and uninterrupted, lubricant between them prevents good frictional engagement.

Therefore, transmission of driving force from the stepping member to the piston is impaired.

The purpose of the present invention is to prevent the piston from returning during pivoting until it rises from the bottom dead center by 1/2 stroke, and even if lubricating oil is present, The object of the present invention is to improve the stepwise rotatable piston of the known type in such a way that an effective frictional engagement occurs during the descent from the position to bottom dead center.

The above object of the present invention is achieved by the following configuration.

That is, according to the invention, the two friction surfaces of the stepping member define conical surfaces inclined with respect to the longitudinal axis of the piston, such that an obtuse angle is formed between the two friction surfaces;
The clearance through which the pressing member can move in the axial direction is larger than the clearance through which the stepping member can move in the axial direction.

Since the two friction surfaces of the stepping member in the present invention are provided with sharp edges, the film of lubricant on these friction surfaces is such that the pressing member and the stepping member are in contact with each other and the pressing member is in contact with the ring. When it makes contact (from just 1/2 of the stroke to the bottom dead center), it breaks off.

A plurality of grooves are formed in the two friction surfaces of the stepping member, and due to the gap defined near each groove (between the stepping member and the pressing member and ring),
As the stepping member decelerates one-half stroke up from bottom dead center, a hydrodynamic wedge of lubricating oil is formed in each of the gaps.

These wedges facilitate disengaging the pusher member from the ring and disengaging the stepping member and pusher member from each other.

Because of this disengagement, the pivoting motion of the piston received from the stepping member during the lowering of the connecting rod from 1/2 stroke to bottom dead center is braked, or The deceleration of the stepping member during the ascent of the connecting rod by one stroke prevents it from returning.

The two conical friction surfaces of the stepping member are each formed with a number of axial grooves located on their outer periphery, the bounding surface of one of each groove transitioning into the friction surface via a sharp edge, The boundary surface is constructed such that a wedge-shaped gap extending around the periphery of the stepping member occurs between the conical friction surface of the pushing member or piston and said other boundary surface.

This feature has two consequences.

That is, the sharp edges separate and skim the layer of oil that exists between the cooperating friction surfaces, thereby ensuring that as the stepping member makes the required pivoting motion, the piston is driven, and that the required pivoting motion is There is free pivoting between the stepping member and the piston when the rotation is slower than the rotation of the piston, and inertial forces cannot separate the cooperating friction surfaces.

An embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, a connecting rod 1 of a reciprocating internal combustion engine has its upper end 8 spherical and is mounted by said upper end in a piston 2, with the connecting rod bearing the piston in a direction perpendicular to the view of FIG. It is pivotable about an axis 3 and the piston 2 can rotate about its upper end 8 about its longitudinal axis 19.

Therefore, the piston 2 has bearing surfaces 4, 5 in the form of hollow spheres above and below the piston bearing axis 3;
is formed in a ring 6 which is pressed against the upper end 8 of the connecting rod by a ring 7 screwed onto the piston 2.

The annular stepping member 10 is internally formed with two axial grooves 13 diametrically opposed to each other and is located in a recess 9 in the upper end 8, the recess 9 being at the same height as the piston bearing axis 3. and is in the form of an annular groove.

Each end of the piston pin 14 engages in a groove 13, the axis 23 of the piston pin 14 passing through the center point of the upper end 8 of the connecting rod 1, and the piston pin 14 being inclined with respect to the piston bearing axis 3.

As a result of this arrangement of the piston pin 14, its ends form two drive members for the stepping member 10, which can reciprocate about the longitudinal axis 19 of the piston in response to the pivoting movement of the connecting rod 1. Pivot.

Is the stepping member 10 on its outer surface? friction surfaces 11
and 12, the friction surfaces being conical with respect to the longitudinal axis 19 of the piston and extending in a direction opposite to the bearing axis 3 and comprising an angle of approximately 140° between them.

The friction surface 11 cooperates with a corresponding friction surface on the inside of an annular pressure member 15, which is guided for axial movement within the piston 2 but not rotatable relative to the piston 2. Can not.

The top of the pressing member 15 is thus formed with two or more radial slots 16, each slot engaging a pin 17 fixed to the piston 2.

The friction surface 12 of the stepping member 10 cooperates with a corresponding friction surface on the inside of a ring 18, which is rigidly fixed to the ring 6 by means of screws (not shown) and thus rigidly attached to the piston 2 via the ring 7. is connected to.

The stepping member 10 has an axial play (S) with respect to the piston 2.

The upward play of the stepping member 10 is stopped by the stop ring 20.
The stop ring 20 is fixed by a screw 21 to the shoulder of the piston 2 above the stepping member 10.

The pressing member 15 has an axial play with respect to the piston 2, but this play is larger than the play of the stepping member 10, and in the illustrated example, the size is 2S.

As shown in FIGS. 2 and 3, the sloping friction surfaces 11 and 12 of the stepping member 10 are provided with a plurality of axial grooves 25.
are formed, and these grooves have a uniform depth to the friction surfaces 11, 12 along their longitudinal direction.

Each groove 25 is defined on its right side in FIG. 3 by a vertical surface 26 which transitions outwardly into the friction surface 11 or 12 via a sharp edge 2γ.

The other bounding surface 28 of each groove 25 is adapted to form a wedge-shaped gap between it and an opposing conical friction surface on the pressure member 15 or ring 18 .

When relative rotation occurs in the direction of arrow 30 in FIG. 3 and the masses of the pushing member 15 and stepping member exert a downward force to accelerate or decelerate the piston, the friction surfaces 11 and 12 press Frictionally engages the friction surfaces of member 15 and ring 18, respectively.

Sharp edges 27 aid in the frictional engagement by disrupting the lubricant layer between the cooperating friction surfaces.

However, due to the wedge-shaped bounding surface 28,
Following frictional engagement, when the pivoting speed of stepping member 10 falls below the rotational speed of the piston, stepping member 10 acts as a free wheel.

The free wheel effect is assisted by lubricant penetrating between the cooperating friction surfaces.

The stepwise rotatable piston described above operates as follows.

Starting from the top dead center position of the piston 2, the piston descends and the pressing member 15 and the stepping member 10 are in their highest position due to their inertial forces.

As a result, the friction surface 11.12 of the stepping member 10
is disengaged from the associated friction surfaces of the pressing member 15 and the ring 18, so that the opposite pivoting of the stepping member 10 has no effect on the piston 2.

In addition to the descending movement, the piston 2 moves the stepping member 1
0's previous drive results in a unidirectional rotation, the speed of which decreases rapidly.

The stepping member 10 begins to pivot in one direction through 90 degrees after ten dead center, and the speed of this pivot increases with increasing crank angle.

As a result of the inertial forces of the pushing member 15 and the stepping member 10, both members begin to move within the piston towards the friction surface of the ring 18.

When the rotational speed of the piston 2 and the pivoting speed of the stepping member 10 reach the same value, the piston 2 begins to be effectively driven by the stepping member due to the frictional engagement between the cooperating friction surfaces.

The piston 2 begins to be driven in this way at about 45° before reaching bottom dead center.

Since the pivot speed continues to increase from this point, the rotational speed of the piston continues to increase until bottom dead center is reached.

In such a position, the pivoting speed of the stepping member 10 decreases even more rapidly than the rotational speed of the piston, even though the inertial forces of the stepping member 10 and the pushing member 15 do not yet separate the cooperating friction surfaces from each other. However, a hydrodynamic wedge of lubricating oil is formed between the wedge-shaped interface surface 28 and the friction surfaces of the ring 18 and the pushing member 15, so that the stepping member 10 and the pushing member 15 are prevented from engaging each other. It begins to disengage, so that the stepping member now acts as a free wheel.

Therefore, the rotation of the piston is not slowed down as a result of the stepping member pivoting more slowly.

The pivoting of the stepping member 10 reverses its direction again at 90° after bottom dead center, i.e. the pivoting is in the other direction, but the stepping member 10 and the pushing member 15 remain in the first position within the piston due to their inertia. The pivoting in the other direction does not affect the rotation of the piston as it begins to move towards the position shown in the figure.

With each actuation by the stepping member 10, the piston is given a new pivoting motion in the desired direction.

Alternatively, each bounding surface 28 may be replaced by a stepped surface of known hydrodynamic actuation which is recessed relative to the friction surface 11 or 12.

[Brief explanation of the drawing]

1 is an axial cross-sectional view of a portion of a stepwise rotatable piston according to the invention; FIGS. 2 and 3 are elevational and plan views of the stepping member; and FIG. 4 is a piston according to the prior art. FIG. 3 is a cross-sectional view in the axial direction. In the figure, 2: piston, 10: stepping member,
IL12: Friction surface, 15: Pressing member, 19: Longitudinal axis of piston, 25: Groove, 26, 28: Boundary surface, 2
7: Etsuji.

Claims (1)

[Claims] 1. A stepwise rotatable piston for a reciprocating internal combustion engine, the stepping member being mounted on a connecting rod for rotation about its longitudinal axis and having two friction surfaces, the stepping member being The piston is adapted to pivot reciprocally about the longitudinal force axis of the piston in response to pivoting of the rod, said one friction surface cooperating with a corresponding friction surface of the piston, and said other friction surface cooperating within the piston. stepwise rotation, in cooperation with a corresponding friction surface of a pushing member adapted to move along said longitudinal axis, in which the operative connection between said stepping member and the piston is caused by the inertia of said pushing member and stepping member; In a possible piston, the two friction surfaces 11.12 of the stepping member 10 extend conically with respect to the longitudinal axis 19 of the piston and are at an angle with respect to each other, and the axial clearance of the pressing member 15 is The two conical friction surfaces 11.12 of the stepping member 10 are each formed with a plurality of axial grooves 25 located on the outer periphery of the stepping member, each of which is larger than the axial clearance of the stepping member 10. One boundary surface 26 of the groove 25 has a sharp edge 2
7 to the friction surface 11 , 12 , the other bounding surface 28 of each groove 25 is such that a gap extending in the form of a wedge around the stepping member 10 is connected to the opposing conical surfaces of each of the pressing member 15 and the piston 2 . A stepwise rotatable piston for a reciprocating internal combustion engine, characterized in that the piston is adapted to be formed between a shaped friction surface and the boundary surface 28.