RU2253779C1 - Cam-and-lever mechanism - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: cam-and-lever mechanism comprises cam shaft (1) with cam (2) asymmetrical with respect to the main axis of the mechanism which passes through the center of cam shaft (1), which is the axis of rotation, and the point of cam (2) most distant from the center of cam shaft (1), top lever (9) and bottom lever (16), link (22) for providing levers (9) and (16) to operate synchronously and the distance between centers (3) and (10) of the axles of bearing (5) and (12) to be constant, and connecting rod (31) secured to top lever (9) at a distance from center (8) of the axle of top lever (9) to the housing. The first ends of levers (9) and (16) are secured inside the housing so that center (3) of the axle of bearings (5) in race (4) at the second end of top lever (9) and center (10) of the axle of bearings (12) in race (11) at the second end of bottom lever (16) are arranged oppositely with respect to the center of cam shaft (1) and at the main axis of mechanism when they are in the top or in the bottom position. Connecting rod (31) causes the piston to move between the top and bottom position of centers (3) and (10) of the axles of bearings (5) and (12) in levers (9) and (16).

EFFECT: enhanced efficiency.

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Description

The technical field to which the invention relates, and the preferred area of its use.

The claimed invention relates to the field of mechanical engineering and can be used in technology where it is necessary to convert the reciprocating motion into rotational motion. It can be used to create internal combustion engines and steam engines with a high efficiency.

Analogue characteristic

Known cam mechanism / see MKI F 16 H 25/14; F 16 H 53/02, Aut. USSR No. 174480 dated 08/27/1965 /. It contains a camshaft with roller or flat followers. The shape of the cams is symmetrical. When the shaft rotates, the cams move the pushers. This mechanism is used as a software device to ensure the order of the elements of any mechanism. But as a device for converting reciprocating motion into rotational motion, it is not used in technology.

Criticism of devices having a crank mechanism

Known devices for converting reciprocating motion into rotational motion: "Eccentric Crank-Slider Mechanism" / see MKI F 16 H 21/14, ed. St. USSR No. 11109699A dated 08.30.80 / and "CRANKSHAFT ROD" / cm. MKI F 16 H 21/14, ed. St. USSR No. 1110969 A dated 08.30.80 /. The latter is widely used in modern technology. These mechanisms have a low efficiency due to the shortcomings of the crank mechanism included in them: the equilibrium of their systems at the moment of application along the axis of the slider / connecting rod / the greatest force arising at the time of ignition of the combustible mixture in the chamber above the piston. The force acting around the circumference formed by the rotation of the center of the eccentric neck / connecting rod neck / relative to the center of the crankshaft main journal at this moment is not at all. This force appears, and then gradually increases as the center of the eccentric / connecting rod / crankshaft center leaves and leaves the top dead center under the action of the flywheel. In the crank mechanism, the skew of the piston reduces the efficiency of the mechanism. In the eccentric crank-slide mechanism, when converting the reciprocating motion of the slider to the rotational movement of the shaft, no less losses are caused by the misalignment of the piston in the crank mechanism.

The purpose of the invention

Increase the efficiency of the device for converting reciprocating motion into rotational motion.

SUMMARY OF THE INVENTION

The cam lever mechanism contains: cam shaft / cm. figure 1 / with an asymmetric shape of the cam / 2 / relative to the main axis of the mechanism drawn through the center of the shaft / O /, which is the axis of rotation, and the point farthest from the center of the shaft / A / of the cam; the upper lever / 9 / and the lower lever / 16 /, which at one end are fixed in the housing so / points 8 and 15 /, so that the center / 3 / axis of the bearings / 5 / in the volume / 4 / of the upper lever and the center / 10 / axis the bearings of bearings / 12 / in the cage / 11 / of the lower lever occupied the opposite position relative to the center of the shaft / О / and were on the main axis at the moments when they were in the upper or lower position, which would provide a constant distance between the centers of the axles / 3 and 10 / with a constant contact of the surfaces of the bearing race with the surface of the cam during periods of movement r upper position to the lower position and the lower position to the upper position; a bunch / 22 / - for synchronous operation of the levers and ensuring a constant distance between the centers of the axes of mounting the bearings in the cages during operation of the mechanism, and a connecting rod / 31 /, mounted on the axis / 32 / on the upper arm at a distance from the center / 8 / axis of its mounting to a housing providing a piston stroke corresponding to the distance between the upper / 3 and 10 / and lower / 6 and 13 / position of the centers of the axes of the bearings in the levers.

The cam-lever mechanism may have an upper position when the farthest point of the cam / A / will be in contact with the cage of the bearings of the upper arm, and a lower position when the cam rotates 180 degrees and its farthest point will be in contact with the cage of the bearings of the lower arm but he has no top dead center. If you apply force along the axis of the connecting rod / cm. is indicated by the arrow and the letter / P / Fig. 1 / in the direction of the axis of attachment of the bearings of the upper arm, then its action through the cage on the cam located in the upper position will immediately lead to the appearance of a force acting on a circle formed by the rotation of the center / M / working surface cam relative to the center / O / shaft / 1 /, or relative to the axis of rotation of the shaft.

Concrete example

проводится окружность, обозначающая вал /1/. От центра вала /О/ на оси У вверх откладывается отрезок, равный /l/ и находится на оси точка /А/. Это будет самая дальняя точка кулачка от центра вала /О/. Затем выбирается диаметр /Д/ дуги рабочей поверхности кулачка, соответствующий замыслу изготовителя. При выборе диаметра дуги рабочей поверхности кулачка следует исходить из того, что чем больше диаметр ее, тем дальше будет находиться центр рабочей поверхности от центра вращения вала, тем будет больше эффективность преобразования возвратно-поступательного движения во вращательное движение, но только в первую половину рабочего хода поршня. Выбор большего диаметра приводит к уменьшению угла поворота кулачка от верхнего положения, в период которого возможно преобразование силы, действующей вдоль оси шатуна в силу, действующую по окружности. При диаметре рабочей поверхности, равной 1,5 l, преобразование силы, действующей вдоль оси шатуна, в силу, действующую по окружности, возможно при повороте кулачка на 170 градусов от верхнего положения. Если рабочую поверхность выполнить прямой линией /см. обозначена штриховой линией на фиг.1/, то преобразование возможно только при повороте кулачка на 80 градусов. Исходя из этого диаметр рабочей поверхности следует выбирать не менее 1,5 l, не более 1,7 l.For a specific implementation of the device, data is required: the distance from the upper position of the connecting rod to the lower position / l /, or the stroke of the piston, and the diameter of the shaft / d /. Conducted on paper axis X and U / cm. figure 1 /. Their intersection at the point / O / will be the center of the shaft. This point will also indicate the axis of rotation. From center / o / radius

the circle marking the shaft / 1 / is drawn. From the center of the shaft / O / on the Y axis, a segment equal to / l / is laid up and is located on the axis of the point / A /. This will be the farthest point of the cam from the center of the shaft / O /. Then, the diameter / D / arc of the working surface of the cam is selected, according to the manufacturer’s plan. When choosing the diameter of the arc of the working surface of the cam, one should proceed from the fact that the larger the diameter, the farther the center of the working surface from the center of rotation of the shaft will be, the greater will be the conversion efficiency of the reciprocating motion into rotational motion, but only in the first half of the working stroke piston. The choice of a larger diameter leads to a decrease in the angle of rotation of the cam from the upper position, during which it is possible to convert the force acting along the axis of the connecting rod into a force acting around the circumference. With a diameter of the working surface equal to 1.5 l, the transformation of the force acting along the axis of the connecting rod into a force acting around the circumference is possible when the cam is rotated 170 degrees from the upper position. If the working surface is executed with a straight line / cm. indicated by the dashed line in figure 1 /, the conversion is possible only when the cam is rotated 80 degrees. Based on this, the diameter of the working surface should be selected not less than 1.5 l, not more than 1.7 l.

из точек /А и Б/ во втором секторе наносятся дуги и на пересечении их отмечается точка /М/. Эта точка является центром дуги рабочей поверхности кулачка. Этим же радиусом из точки /М/ от точки /А/ до точки /Б/ проводится дуга, которая обозначает рабочую поверхность кулачка /2/.1, 11, 111, 1U - sectors are indicated. In the fourth sector on the circumference of the shaft is the point / B /. At this point, a smooth transition of the arc of the cam working surface to the shaft circumference / 1 / will be realized. With a diameter of the working surface of 1.5 l point / B / will be located approximately in the middle of the arc of the shaft IU sector. If the diameter of the arc of the working surface is increased, then this point will shift to the X axis. Then, with a radius

from points / A and B / in the second sector arcs are drawn and the point / M / is marked at their intersection. This point is the center of the arc of the cam working surface. The same radius from point / M / from point / A / to point / B / draws an arc that indicates the working surface of the cam / 2 /.

Через точку /7/ проводится перпендикулярная линия относительно главной оси механизма, которая совпадает с осью У. На этой линии отрезком, равным на менее 1,2 l от точек /3 и 6/ находится точка /8/, являющаяся центром оси крепления верхнего рычага к корпусу. Длина рычага обусловлена тем, чтобы при вращении кулачок самой дальней частью от центра вала не цеплял за рычаг в месте крепления его к корпусу. Длину рычагов можно сделать больше. Это позволит уменьшить отклонение нижней части шатуна в месте крепления его к рычагу от главной оси устройства при перемещении его их верхнего положения в нижнее положение и из нижнего положения в верхнее положение. Далее обозначается рычаг /9/.The magnitude of the bearings and the bearing race is determined by conventional calculation, depending on the forces acting on them. On the axis / Y / from the point / A /, a segment equal to the radius of the outer circumference of the bearing race is the point / 3 /. This point is the center of the axis of the bearings in the lever. The same radius from the point / 3 / draws a circle denoting the bearing race / 4 /. From the center / 3 /, a circle is drawn indicating the axis of the bearing mounting, and a circle is drawn indicating the bearing / 5 /. This bearing and, therefore, the cam are marked when they are in the upper position. Then from the point / 3 / in the direction to the center of the shaft / О / with a segment equal to / l /, on the Y axis, or on the main axis, is the point / 6 /. This point indicates the position of the center of the axis / 3 / at the time it is in the lower position. From points / 3 and 6 / there is a point / 7 /, indicating the middle

A point perpendicular to the main axis of the mechanism is drawn through point / 7 /, which coincides with the Y axis. On this line, a point equal to less than 1.2 l from points / 3 and 6 / is the point / 8 /, which is the center of the axis of attachment of the upper arm to the body. The length of the lever is due to the fact that during rotation the cam farthest from the center of the shaft does not cling to the lever at the point of attachment to the housing. The leverage can be made longer. This will reduce the deviation of the lower part of the connecting rod at the place of attachment to the lever from the main axis of the device when moving its upper position to the lower position and from the lower position to the upper position. Next, the lever / 9 / is indicated.

точка /14/. Через точку /14/ проводится перпендикулярная линия относительно главной оси механизма. От точек /10 и 13/ отрезком, равным не менее 1,2 l на этой линии определяется точка /15/, которая является центром оси крепления нижнего рычага к корпусу. Затем обозначается нижний рычаг /16/.A similar method determines the lower lever system. From the point / N / of the intersection of the axis / Y / with the shaft circumference / 1 / with a segment equal to the outer radius of the bearing race, on the main axis is the point / 10 /, which is the center of the axis of the bearings in the lower arm. From this point, the same radius draws a circle denoting the bearing race / 11 /, and draws a circle denoting the axis of attachment of the bearings to the lower arm, and draws a circle denoting the bearing / 12 /. This bearing is marked when it is in the upper position. Then, from the point / 10 / on the axis / Y / down from the center of the shaft with a segment equal to / l /, there is the point / 13 /, which indicates the center of the axis of attachment of the bearings to the lower lever, when it is in the lower position. Between points / 10 and 13 / is the middle

point / 14 /. A point perpendicular to the main axis of the mechanism is drawn through the point / 14 /. From points / 10 and 13 / with a segment equal to at least 1.2 l on this line, point / 15 / is determined, which is the center of the axis of attachment of the lower arm to the housing. Then the lower lever / 16 / is indicated.

The working surface of the cam is the one on which the force is applied from the bearing cage during the stroke of the piston, or during the period of action of the force arising from the combustion of the combustible mixture in the chamber above the piston. The working surface of the cam is indicated by bold lines / cm. figure 1 /. A working bearing is one on which a force is applied acting along the axis of the connecting rod during the stroke of the piston. Working bearings are bearings in the cage of the upper arm.

The attachment points of the levers / 7 and 15 / can be shifted to the side of the axis / X / or in the opposite direction, but their movement will lead to problems due to the difficulty of maintaining a constant distance between the centers of the bearings / 3 and 10 /. It should be noted that a constant distance between the centers of the axes of these bearings and their presence on the main axis at the moments when they are in the upper or lower position is a condition for the normal operation of the mechanism. To create a system, for synchronous operation of the levers and to maintain a constant distance between the centers / 3 and 10 / of the axes of the bearings, a bunch is needed. On the upper lever / 9 / at a distance arbitrarily chosen by the manufacturer from the point / 8 /, on the lever axis is the point / 17 /, which is the center of the axis of attachment of the ligaments to the lever. Then a circle is drawn from this point, indicating the axis of attachment of the ligaments to the lever. On the lower lever is attached a device that creates a force, pulling the lever / 9 and 16 / to each other. Lever / 19 / device / cm. figure 1 / one end on the axis / 18 / is attached to the lever / 16 /. In the middle of the lever / 19 / the axis / 20 / is mounted, to which the ligaments / 22 / are attached. Between the other end of the lever / 19 / and the surface of the lever / 5 / a spring / 21 / is installed. On the axis / 17 / of the upper lever / 9 / and the axis / 20 / of the lever / 19 / symmetrically to the axis of the levers / 9 and 16 / / cm. figure 2 / are attached two ligaments / 22 /. The distance between the ligaments should be such that a fist passes between them during its rotation. Axes / 17 and 20 / must be installed at the same distance from the centers of the axes / 8 and 15 / of the mounting levers to the housing. The force that the spring / 21 / must create must be equal to the force arising along the axis of the connecting rod at the time of maximum compression of the combustible mixture in the combustion chamber.

The bonding device can be performed in another way. The levers / 9 and 16, see figure 3 / are longer in the direction opposite to the ends on which the bearings are mounted in the cages. The length of the shoulders / 23 and 24 / levers is determined by the manufacturer. But the shorter the leverage shoulders, the more spring should create more force. On the shoulder of the upper lever / 23 /, the axis / 25 / is mounted, and on the shoulder / 24 / of the lower lever, the lever / 27 / is mounted on the axis / 26 /. In the middle of the lever / 27 / the axis / 28 / is mounted. Between the second end of the lever / 27 / and the shoulder of the lower lever / 24 / a spring / 29 / is installed. On the axis / 25 / of the upper lever and the axis / 28 / of the lever / 24 /, the ligaments / 22 / are mounted symmetrically to the axis of the lever. In this embodiment, the spring force pushes the shoulders of the levers / 23 and 24 / in opposite directions, and the shoulders of the levers / 9 and 16 / with bearings will be pressed against the cam. The lever / 9 /, in terms of mounting bearings on it in a cage, has a structural element / cm. figure 1 /, on which the connecting rod is mounted. A connecting rod / 31 / / cm is attached to the axis / 32 /. figure 4 /.

All details of the mechanism, made according to the intentions of the manufacturer, are made of plastic or plywood and assembled as described. On the cam, only the working surface is made from the point / A / to the point / N /. The upper arm bearing race is in contact with the / A / cam point, and the lower arm bearing race is in contact with the / N / cam point. On the layout, the bundle is made permanent without a spring. Now you should click on the axis / 32 /, or on the connecting rod and rotate the cam 180 degrees so that the bearing bracket of the upper lever without tearing slid over the working surface of the cam from point / A / to point / N /. A cage of bearings of the lower lever marks the inoperative part of the cam. This determines the shape of the cam. From point / B / to point / N /, the arc segment of the working surface coincides with the circumference of the shaft.

The cam-lever mechanism comprises: a cam shaft, the cam shape of which is asymmetric with respect to the main axis of the mechanism, drawn through the center of the shaft, which is the axis of rotation, and the cam point farthest from the center of the shaft; the upper arm and lower arm, one end of which is fixed in the housing so that the center of the bearing mounting axis in the cage at the other end of the upper arm and the center of the bearing mounting axis in the cage at the other end of the lower arm occupied the opposite position relative to the center of the shaft and were on the main axis in moments when they are in the upper or lower position, which will provide a constant distance between the centers of bearing mounting with constant contact of the surfaces of the bearing race with the surface of the cam during periods of their movement eniya from the upper position to the lower position and the lower position to the upper position; ligament - to create a mechanism for synchronous operation of the levers and to ensure a constant distance between the centers of the axes of the bearings during operation of the mechanism, and a connecting rod mounted on the upper lever at a distance from the center of the lever to the housing, providing a piston stroke corresponding to the distance between the upper and lower centers axes for mounting bearings in levers.

To increase the contact area of the surface of the bearing race with the surface of the cam, the surface of the bearing race and the surface of the cam should be performed as shown in Fig.5. In this way, the contact area can be made such that the contact area has the connecting rod neck of the crankshaft with the connecting rod in modern internal combustion engines and even more. The width of the cage of the bearings and the width of the cam can be performed in such a way as to provide a sufficient contact area of them in the manufactured mechanism.

7 shows the cam shaft for a two-cylinder engine with rotation / for balancing / cams 180 degrees. The number / 33 / indicates the flywheel, and the number / 34 / indicates the nut securing the flywheel to the shaft.

If the manufacturer plans to manufacture a cam-lever mechanism for a low-power engine, the cam and bearing cages can be made with smooth surfaces. But in this case, it is necessary to round off the transition of the non-working surface to the working surface of the cam at the point / A / / cm. Fig.6 /. This will slightly reduce engine power, but improve its performance.

The operating principle of the cam lever

When the lever bearings, connecting rod and piston reach the upper position, and the farthest point of the cam / A / is in contact with the bearing bracket of the upper lever, ignition of the combustible mixture in the combustion chamber will occur and the force acting along the axis of the connecting rod, the axis of the bearing through the bearing and its clip is applied to the point / A / cam. As a result, a force immediately appears, acting on a circle formed by the rotation of the center of the working surface / M / / cm. figure 1, is indicated by an arrow / relative to the center of the shaft / About /. The cam rotates, and the cage of the working bearing under the action of force moves along the working surface of the cam. When the cam rotates 180 degrees, the force acting along the axis of the connecting rod will disappear / exhaust gases will be exhausted /. The upper arm bearings are lowered. The cage of the bearings of the lower lever moves along the idle surface of the cam and reaches the lower position when it touches the farthest point of the cam / A / from the center of the shaft. Further, movement from the lower position of the lever bearings to the upper position occurs due to the accumulated energy in the flywheel. The cage of working bearings moves along a non-working surface, and the cage of bearings of the lower lever moves along the working surface to the upper position. When the cam point / A / reaches the cage of the upper bearings, again there will be a force acting along the axis of the connecting rod. Then everything repeats.

Positive effect

In the cam-lever mechanism, two of the most important drawbacks inherent in devices having a crank mechanism are eliminated: the balance of the system at the moment of the greatest force along the connecting rod / slider axis is eliminated and the piston skew when it moves from the upper position to the lower position and from the lower position is eliminated to the top. In the claimed mechanism, 95% of the force acting along the axis of the connecting rod in the initial period of the stroke, provided that the force acting along the axis of the connecting rod is applied perpendicular to the axis of the upper arm, will be converted into a force acting on a circle formed by rotation of the center of the working surface of the cam relative to the center of the shaft.

With a lever length of 1.2 l, with l equal to 45 millimeters, the lower part of the connecting rod deviates from the main axis of the mechanism by only five millimeters, which cannot cause the piston to skew. A slight tilt of the axis of the cylinder can be done so that the specified part of the connecting rod will deviate by 2.5 millimeters in both directions.

The cam-lever mechanism has a very high efficiency converting the reciprocating movement of the connecting rod into the rotational movement of the shaft. With equal parameters of the elements / piston diameter, piston stroke, compression ratio, etc. /, a cam-lever engine will be about twenty times more powerful than an engine with a crank mechanism. On the chart / cm. Fig / given the power characteristic of the device for converting reciprocating motion into rotational motion for an engine of 50 cubic centimeters. The force acting along the connecting rod axis is indicated on the Y axis, and the piston stroke in millimeters is indicated on the X axis. Line / B / denotes a characteristic of the force acting along the axis of the connecting rod in internal combustion engines during the period of the piston stroke. Line / C / - characteristic of the force acting along the axis of the connecting rod in the steam engine. Line / D / - characteristic of the force acting on a circle formed by the rotation of the center of the working surface of the cam relative to the axis of rotation of the shaft, in engines with a cam-lever mechanism. Line / K / - characteristic of the force acting on a circle formed by the rotation of the center of the connecting rod journal relative to the center of the crankshaft main neck in engines with a crank mechanism. Line / F / - characteristic of the force acting on a circle formed by the rotation of the center of the working surface relative to the axis of rotation of the shaft, in steam engines with a cam-lever mechanism at a steam pressure of 1 MPa. The graph shows: steam engines with a cam-lever mechanism are far more economical than internal combustion engines with a crank mechanism. The calculation of the acting forces is made in the static state of the elements of the mechanisms.

In the crank mechanism, the diameter of the circle formed by the rotation of the center of the crank pin relative to the center of the crankshaft main journal, with a piston stroke of 45 millimeters, is also equal to 45 millimeters. In the cam-lever mechanism with the indicated piston stroke and the arc of the working surface equal to 1.7 l, the diameter of the circle formed by the rotation of the center of the working surface of the cam relative to the axis of rotation of the shaft will be - 66 millimeters. In the first mechanism, the lever of application of force is 22.5 millimeters, and in the second mechanism - 33 millimeters. To reveal the real correlation of the power characteristics of these mechanisms, the parameters of the crank mechanism are recalculated. The results are shown in the graph / cm. Fig.8 /.

List of figures of graphic images

Figure 1 shows the cam-lever mechanism assembly and the order of its execution. Figure 2 shows the mounting of the couplers / 22 / and the mounting of the bearings in the cage to the upper arm. Figure 3 shows a variant of the ligament between the upper and lower levers. Figure 4 shows the mounting of the connecting rod to the upper arm. Figure 5 shows the shape of the surfaces of the cam and bearing race to increase their contact area. Figure 6 shows the rounding of the cam at the farthest point from the center of the shaft in the case of a cam and bearing cages with smooth surfaces. 7 shows the cam shaft for a two-cylinder engine with a 180 degree rotation of the cams. On Fig shows the power characteristic of the cam-lever mechanism and devices having a crank mechanism.

Claims (1)

A cam mechanism comprising a cam shaft, characterized in that the cam shape is asymmetric with respect to the main axis of the mechanism through the center of the cam shaft, which is the axis of rotation, and the cam point farthest from the center of the cam shaft, the cam mechanism further comprising upper lever and lower lever, one ends of which are fixed in the housing so that the center of the axis of the bearings in the cage on the other end of the upper lever and the center of the axis of the bearings in the cage on each other the opposite end of the lower arm occupied opposite positions relative to the center of the cam shaft and were on the main axis of the mechanism when they were in the upper or lower position, which will provide a constant distance between the centers of the axes of the bearings with constant contact of the surfaces of the bearing race with the surface of the cam during periods of movement from the upper position to the lower position and from the lower position to the upper position, a bunch - to create a system of mechanism for synchronous operation of levers and ensure a constant distance between the centers of the axes of mounting the bearings during operation of the mechanism, and a connecting rod mounted on the upper arm at a distance from the center of the axis of attachment of the upper arm to the housing, providing a piston stroke corresponding to the distance between the upper and lower positions of the centers of the axes of bearing mounting in the levers.

Images