RU2486390C1 - Rotational movement converter - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: rotational movement converter includes drive and driven shafts and a fixed reaction disc with a radial slot. Disc-cam with a slot, which represents a drive link, is rigidly attached to the drive shaft. Drive disc with a slot, which represents a driven link, is rigidly attached to the driven shaft. Drive and driven links, as well as the reaction disc, interact by means of a connecting link in the form of a rotation body. Drive link slot is curved and it has along the middle line the appearance of a composite closed figure consisting of two pairs of adjacent sections in the form of arcs with variable curvature and arcs with constant curvature. Driven link slot is made in the form of an asymmetric shape with the section made in the form of an arc with variable curvature with angular length of 180°. For drive link, two sections of the slot with constant curvature have different radii of arc R₂>R₁ with common centre. For driven link, middle line is an arc of logarithmic spiral, for which dependance of current value of radius vector R on angle φ of its turn is described with the following expression: R=R₁*exp(b₂*φ), where spiral parameter b₂=In(R₂/R₁)/180°.

EFFECT: enlarging kinematic possibilities of the device.

3 cl, 10 dwg

Description

FIELD OF THE INVENTION

The invention relates to mechanical engineering and can be used in various devices for converting the rotation of the drive shaft into rotational-vibrational motion - rotation with cyclic reversal of the driven shaft coaxially located with it.

State of the art

Known mechanisms for converting unidirectional rotational motion into vibrational [1], in which due to the use of a system of gears of external and internal discontinuous gearing, it is possible to cyclically change the angular speed of the driven shaft, which changes its sign every 360 ° in the angle of rotation, i.e. after one revolution, drive shaft. The interval of reversal of the driven shaft can be less than 360 °, which is achieved by changing the gear ratio of the gears.

Known speed converter ("speed converter") [2, 3], containing the driving and driven shafts, associated driving and driven links in the form of cams, the working surfaces of which are made in the form of curved grooves, through which the power interaction of the driving and driven links by connecting links (one or more), in particular balls. The leading and driven links are made mainly in the form of disks, on a flat surface of which there are grooves of constant cross section along the entire length of the closed loop. The middle lines of the contour of the grooves of the leading and driven links are the arches of the Archimedes spiral, since a linear increment of the radius vector length from its rotation angle takes place in them. Moreover, for the case of the gearbox, the groove curvature of the slower link (slave) is less than the curvature of the faster link (master). Since the speed converter is designed to transmit rotation in any direction (clockwise and counterclockwise), in general, the groove contours of the driving and driven links have axial symmetry. Between the leading and the driven link there is a fixed disk with radial grooves (one or several) - a reaction disk ("reaction-disk"), which allows only oscillatory movement of the connecting links (balls) in the radial direction, and the tangential components of the loads acting from the leading and slave links, compensates for the reactions of the housing of the speed Converter. In [3], the possibility of controlling the speed of the driven unit due to the fact that the reaction disk is driven from an external controlled source of movement ("control") is indicated, however, the mechanism of this control is not disclosed, therefore, it can be assumed that this device does not have a rotation reversal function driven shaft with unidirectional rotation of the drive shaft.

To achieve intermittent motion, it was proposed in [3] to include sections with constant curvature — arcs with a fixed radius — in the groove contour of the driving link, which will allow temporarily fixing the connecting links (balls) in the radial direction and excluding the transmission of movement to the driven link.

A device for transmitting rotation [4] is also known, comprising a fixed Maltese cross, a drive disk and a guide cam with a set of two pairs of grooves in the plan in the form of regular polygons and in the section in the form of rectangular channels that interact by means of connecting links in the form of bodies of revolution , one for each pair of slots. The specified device allows you to change the direction of rotation of the driven shaft from passing to oncoming without reversing the drive shaft. However, changing the direction of rotation of the driven shaft involves stopping the device to carry out its readjustment, in particular for the rearrangement of connecting links such as a roller block.

A fixed element of the device containing radial grooves is called in [4] the "Maltese cross", although it is not. Since the main function of the radial groove is to compensate for the tangential components of the loads acting on the connecting link by the reactions of the device casing, and not to impede the transfer of the radial components of the loads, following [2], the element of the device with the radial groove should be called the reaction disk.

The execution of the guide grooves in the form of regular polygons causes significant shock loads in the connecting links, especially when moving from one face of the groove to another, which is associated with an instantaneous change in the trajectory of movement, for example, a 90 ° rotation, for the case when the groove is in the form of a square.

The specified device does not allow to implement the law of change in the angle of rotation of the output link from time to time, similar to a piecewise linear approximation of a sinusoid, in which uniform rotations in the forward and reverse directions would alternate with stops.

The specified device is designed to transmit rotation in the opposite direction, i.e. It is a converter of rotational motion to reverse motion, therefore, by the combination of features closest to the set of essential features of the invention, it can be selected as a prototype.

The aim of the invention is to expand the kinematic capabilities of the device and transfer the driven shaft to rotational-vibrational motion due to internal cyclic reversal.

Disclosure of invention

This goal is achieved by the fact that in the known rotary motion transducer comprising coaxial drive and driven shafts, a stationary reaction disk with a radial groove, a drive disk that is a driven link and rigidly connected to the driven shaft, a guide cam disk that is a driving link and rigidly connected with a drive shaft, with a set of grooves that interact by means of a link in the form of a body of revolution, the grooves are curved and in the middle line look like a composite closed axisymmetrically of the second figure, consisting of two pairs of mating sections in the form of arcs with variable and arcs with constant curvature, for the leading link, and in the form of an asymmetric figure with a single section in the form of an arc with an angular length of 180 °, with variable curvature for the driven link.

The instantaneous change in the direction of rotation of the driven shaft from passing to the oncoming and vice versa (cyclic reversal) is associated with the occurrence of high dynamic (shock) loads in the kinematic elements of the device, so it is advisable to alternate the intervals of rotation itself with short stops (dwells). However, the presence of such stops leads to the need to make the movement of the driven shaft in the associated direction with an angular velocity greater than the angular velocity of the drive shaft. So, if the total duration of the stand is expressed in fractions p <1 of the period of rotation of the drive shaft, then to rotate the driven shaft 180 °, the drive shaft should turn (1-p) * 180 °, and the difference p * 180 ° “lose” by standing . In this case, the angular velocity of the driven shaft in the passing direction should be M times greater than the angular velocity of the drive shaft, where M = 1 / (1-p).

It is impossible to use the principle of converting the movement of the leading link into the movement of the driven link used in the prototype, because the contours of the grooves on the driving and driven links are identical and at any time axisymmetric with respect to the axis of the groove of the reaction disk and, therefore, provide constant equality of the angular velocities of the driven and driving links. This constancy is caused by the fact that the angle between the tangent to the groove of the groove (face) and the groove axis of the reaction disk, although changing from 90 ° to half the angle at the top of the contour, remains the same due to symmetry for the groove of the guide cam disk and for the drive groove drive. But the tangent of this angle has the meaning of the derivative of the contour line with respect to the rotation angle (time), which means that the angular velocities of the driven and leading links are equal.

It is known that the logarithmic spiral [5] is characterized by the fact that "the angle formed by the tangent at an arbitrary point of the logarithmic spiral with the radius vector of the point of tangency is constant." This, in turn, means the constancy of the derivative of the radius vector with respect to the angle of rotation.

Therefore, if the grooves of the guide cam disk and the drive disk are made in the form of logarithmic spirals that are identical in shape but different in the direction of the twist of the turns, then the interaction of the leading and driven links through the connecting links and the groove of the stationary reaction disk will occur with a constant angular velocity of the driven link equal but opposite in sign of the angular velocity of the leading link.

If, however, a difference in the angular velocities of the driven and driving links is required, then it can be provided with the help of corresponding grooves that are not identical in shape. So if the equation in polar coordinates of the middle line (1) of the groove of the guide disc-cam is written in the form r ₁ = a ₁ * exp (b ₁ * φ), and the equation of the middle line (2) of the groove of the drive disc in the form r ₂ = a ₂ * exp (b ₂ * φ), where φ is the angle of rotation of the radius vector, then at the intersection of the middle lines of the grooves, the angular velocities of the links of the leading ω ₁ and the driven ω ₂ will be referred to as ω ₁ / ω ₂ = b ₂ / b ₁ . If we require that ω ₂ / ω ₁ = M> 1, then b ₂ = b ₁ / M, i.e. the curvature of the 2nd line should be greater than the 1st.

To ensure the dwell, it is necessary that the normal to the surface of the groove, along which the force interaction of the groove and the connecting link occurs, passes through the axis of rotation of the leading link. This condition meets the section of the groove, made in the form of a circular arc with a center on the axis of rotation.

Thus, the goal of ensuring the possibility of transmitting the driven shaft to rotational-vibrational motion due to internal cyclic reversal is achieved by performing the groove of the guide cam disk consisting (in the midline) of four sections: two sections in the form of circular arcs of different radii R ₁ and R ₂ > R ₁ with a common center for holding the stand and two sections in the form of arcs of a logarithmic spiral, for which the dependence of the current value of the radius vector R on the angle φ of its rotation is described by the expression R = R ₁ * exp (b ₁ * φ), and d For the groove of the driven link, the middle line is an arc of a logarithmic spiral, for which the dependence of the current value of the radius vector R on the angle φ of its rotation is described by the expression R = R ₁ * exp (b ₂ * φ), where the spiral parameter b ₂ = ln (R ₂ / R ₁ ) / 180 °, the curvature of which at similar points (with the same value of the radius vector) is greater than the spiral along which the groove of the guide cam disk is made.

Brief Description of the Drawings

Figure 1a shows time diagrams of the change in the angle of rotation φ _{1 of the} drive shaft rotating at a constant angular velocity ω ₁ and the angle of rotation φ _{2 of the} driven shaft in the form of a piecewise linear approximation of a sinusoid with nodal points 1, 2, 3, and 4 and period T = 2π / ω ₁ .

On figb, shows an illustration of the mechanism of influence of the curvature and the direction of the twist of the spiral of the middle line of the groove of the driven link on the magnitude and direction of its angular velocity ω ₂ .

On figa shows the axisymmetric contour (dashed line) of the groove of the leading link with the middle line consisting of four sections: two with constant radii of curvature R ₁ and R ₂ and two spiral - with the right "r" (clockwise) and left “ l ”(counterclockwise) by twisting the spiral. Sectors corresponding to areas with constant radii of curvature R ₁ and R ₂ , on which the slave link is maintained, are indicated by the numbers 1 and 2, respectively. They also serve as the numbering of the stand itself: stand No. 1 and stand No. 2

On figb shows the contour (solid line) of the groove "d" of the driven link, the middle line of which is made in a logarithmic spiral such that the minimum radius vector R ₁ and the maximum radius vector R _{2 are the} same with the corresponding radii of curvature R ₁ and R ₂ on figa and are connected by the ratio R ₂ = R ₁ * exp (b ₂ * 180 °), and, conversely, the spiral parameter b ₂ = ln (R ₂ / R ₁ ) / 180 °. The contour of the radial groove "g" of the reaction disk, the length of the rectilinear part of which is equal to the difference R ₂ -R _{1, is} also shown there.

Figure 3 shows a longitudinal section of the Converter.

The converter contains a drive shaft 1, a driven shaft 2, a cam-drive disk (drive link) 3, a drive disk (driven link) 4, a link 5, a reaction disk 6 with a radial groove 7. The shafts 1 and 2 are mounted on bearings in the housing 8 , half of which are centered. The reaction disk 6 is rigidly connected to the housing 8.

Figure 4 shows the positions of the groove of the leading link (dashed line), the groove of the driven link (solid line) and the link (circle filled with black), corresponding to the various nodal points of the time diagram in Fig. 1a, namely:

- in Fig. 4a, the position of the links at point 3 is the end of the stand No. 2, the beginning of the oncoming movement of the driven link;

- in Fig.4b the position of the links at point 4 is the end of the oncoming movement of the driven link, the beginning of the stand No. 1;

- Figv position of the links at point 1 - the end of the stand No. 1, the beginning of the satellite movement of the driven link;

- in Fig. 4d, the position of the links at point 2 is the end of the satellite movement of the driven link, the beginning of stand No. 2.

The implementation of the invention

The invention can be implemented in the form of the device depicted in figure 3. When transmitting rotation from an external source to the drive shaft 1, the guide disc-cam 3 (drive link) rotates around its axis, for example, counterclockwise, as in FIG. 4. When this guide disc-cam 3 through the working surface of its groove acts on the connecting link 5, for example a ball. The radial groove 7 in the reaction disk 6, mounted in the housing 8, does not allow the connecting link 5 to move in a direction other than the radial, making oscillating movements during one revolution of the driving link 3. Moreover, in the sections of the groove of the guide disc-cam 3 with a constant radius the curvature of the link 5 temporarily stops the movement in the radial direction, and consequently, the transmission of movement to the driven link 4, which means the idle of the driven shaft 2. In sections of the groove of the guide disc-cam 3 with a variable radius of curvature us link 5 moves toward the center of the reaction disk 6 when the groove portion of the guide-cam disk 3 has a left spiral twist ( "l" in Figure 2) and from the center - right if ( "r" in Figure 2). The connecting link 5, acting on the external or internal surface of the groove of the drive disk (driven link) 4, makes it rotate clockwise, as in Fig.4b, or counterclockwise, as in Fig.4d, respectively.

The groove of the guide disc-cam 3 at similar points has a curvature smaller than the groove of the drive disc 4, which leads to a difference in the angular velocities of the driving ω ₁ and driven ω ₂ links. As follows from Fig. 16, in order for the connecting link 5 in the radial groove 7 to shift by dR, it is necessary to rotate the guide disc-cam 3 at an angle δφ ₁ . In this case, the displacement of the link 5 by dR is possible only when the drive disk 4 is rotated through an angle δφ ₂ . But δφ ₂ > δφ ₁ , which means ω ₂ > ω ₁ , and this is true for any twist of the spiral of the midline of the groove of the guide disc-cam 3.

Thus, the left-side branch "l" of the groove of the cam-disk 3 is responsible for the right (clockwise) rotation of the drive disk 4 by 180 °, the right-hand branch "r" of the groove of the cam-disk 3 is responsible for the left (counterclockwise) rotation drive disk 4 by 180 °, and the groove sections of the guide disk-cam 3 with constant curvature are responsible for ensuring the stand before reversing the drive disk 4.

Information sources

1. Pat. US 3,516,267, 1970.

2. Pat. US 5312306, 1994.

3. Pat. EP 0575561 B1, 1997.

4. Pat. SU 1556214, 1995.

5. www.ru.wikipedia.org> wiki / Logarithmic spiral.

Claims (3)

1. A rotary motion transducer comprising coaxial drive and driven shafts, a stationary reaction disk with a radial groove, a drive disk being a driven link and rigidly connected to the driven shaft, a cam cam disk, which is the driving link and rigidly connected to the drive shaft, with a set grooves that interact through a link in the form of a body of revolution, characterized in that, in order to expand the kinematic capabilities of the device and transmit to the driven shaft a rotational-vibrational motion Due to the internal cyclic reversal, the grooves are made curved and in the middle line look like a composite closed axisymmetric figure, consisting of two pairs of mating sections in the form of arcs with variable and arcs with constant curvature for the leading link, and in the form of an asymmetric figure with a single section in the form arcs with an angular length of 180 °, with variable curvature for the driven link, moreover, for the leading link, two sections of the groove with constant curvature must have different arc radii R ₂ > R ₁ with a common center, and for the groove of the driven link, the middle line is an arc of a logarithmic spiral, for which the dependence of the current value of the radius vector R on the angle φ of its rotation is described by the expression R = R ₁ · exp (b ₂ · φ), where the spiral parameter b ₂ = ln (R ₂ / R ₁ ) / 180 °. 2. The Converter according to claim 1, characterized in that, for the purpose of transmitting to the driven shaft a rotational-vibrational movement with stops preceding its reversal, with a duration expressed in fractions p <1 of the rotation period of the drive shaft, for the groove of the drive link the middle line of sections with variable curvature is an arc of a logarithmic spiral for which the dependence of the current value of the radius vector R on the angle φ of its rotation is described by the expression R = R ₁ · exp (b ₁ · φ), where the spiral parameter b ₁ = b ₂ / (1-p ) 3. The Converter according to claim 1, characterized in that, in order to simplify the design, the connecting link in the form of a body of revolution has the shape of a ball.

Images