DESCRIPTION

[001] The present invention relates to antiparallelogram linkage mechanisms and their use in wing drive mechanisms.

[002] Antiparallel four-bar linkage mechanism or antiparallelogram linkage mechanism is a well-known mechanism. The antiparallelogram linkage mechanism comprises stationary link, two pivotally joined cranks and the connecting rod, pivotally joined to the rotating ends of the cranks. The cranks are rotating in opposite direction so that the axis of the said stationary link is crossing the axis of the said connecting rod. The midpoint of the connecting rod will trace a lemniscate or figure eight curve. The antiparallelogram has two points of instability, in which it can be converted into a parallelogram and vice versa.

[003] A number of solutions has been designed to overcome the above stated shortcoming.

[004] The first example, which can be considered as the closest prior art, represents an antiparallel linkage mechanism, containing leading and driven cranks rotating in different directions, each of which is pivotally connected to the connecting rod and the stationary link, and the device for taking the mechanism out of the points of instability, made in the form of non-circular toothed sectors separately mounted on each crank. During one rotation cycle the toothed sectors twice engage with one another in dead positions of the mechanism (S. N. Kozhevnikov et al., "Mechanisms” (in Russian), Moscow, Mechanical engineering (in Russian), vol. 4, p. 93, Fig. 2.78, 1965). The disadvantage of this mechanism is the low reliability of operation due to the additional dynamic loads arising from the impact interaction during the engagement of the said toothed sectors, as well as the high cost of manufacturing non-circular toothed sectors.

[005] The second design represents an antiparallelogram linkage mechanism containing rotating in different directions leading and driven cranks pivotally connected to the connecting rod and the stand (stationary link), and a device for taking the mechanism out of the points of instability, made in the form of separately mounted on the cranks, links of a cam mechanism. During one rotation cycle the said links of the cam mechanism twice engage with one another in dead positions of the said antiparallelogram linkage mechanism (S. N. Kozhevnikov et al, "Mechanisms" (in Russian), Moscow, Mechanical engineering (in Russian), vol. 4, p. 93, Fig 2.76 1965). The disadvantages of this solution are low reliability of operation due to the additional dynamic loads arising from the impact interaction during the engagement of the said links of the cam mechanism, as well as the high costs of precise manufacturing of complex profiles of these links.

[006] The third design is disclosed in the Russian federation patent publication No. RU 2196263. The solution represents the mechanism of the articulated anti -parallelogram, containing leading and driven cranks rotating in opposite directions, as well as a device for taking the mechanism out of the points of instability, the latter is made in the form of two links separately firmly mounted on the axles of the cranks on opposite sides of the line of their centres of rotation, installed with unequal angular displacement relative to each of the cranks and pivotally interconnected by means of an elastic element, for example, in the form of a compression-tension spring. The disadvantage of this design is complexity to embody it in practice, because of the axis of the said connection rod and the axis of the said elastic element are intersecting in the plane. The second disadvantage is increased nonuniformity of movement caused by the introduction of the said elastic element.

[007] The aim of the present invention is to design an antiparallelogram linkage mechanism without points of instability as well as to overcome shortcomings already mentioned in analysing the state of art.

[008] Proposed invention is based on the fact that there are two points on the axis of the stationary link of the antiparallelogram, such that in any position of the said antiparallelogram the angles between the longitudinal axis of the said stationary link and the lines drawn pairwise to connect one of said point with the rotating end of the closest crank of the antiparallelogram are equal in magnitude and opposite in direction.

[009] Thus, by introducing to the antiparallelogram linkage mechanism two additional guides of variable length, each of which is pairwise pivotably connected with one end to the stationary linkages and with the other end has common pivot connecting it to the connection rod and one of the cranks of the antiparallelogram linkage mechanism, so that the ratio of the length of the said crank to the length of the said connecting rod is equal to the ratio of the distance between the centers of the pivots, by which of one of the cranks and the closest variable length guide are attached to the stationary link, and introducing a kinematic connection between the said variable length guide so that rotating one of the said variable length guide at a certain angle is causing rotation of the other of the said links at an angle that is equal in magnitude and opposite in direction, can eliminate the points of instability inherent by the antiparallelogram linkage.

[010] Compared to the solutions that are discussed hereinabove the proposed solution provides smooth movement of the antiparallelogram linkage because of permanent contact between all moving parts of the mechanism for taking the antiparallelogram linkage from its points of instability.

[Oil] The present invention is an antiparallelogram linkage mechanism comprising a stand, a two pairs of axles, i.e., a first and a second axle, and a third and a forth axle, a pair of stationary linkages, i.e., a first and a second stationary linkage, a pair of variable length guides, i.e., a first and a second variable length guide, a pair of cranks, i.e., a first and a second crank, and a connection rod.

[012] All four axles are aligned on a common axis.

[013] The first stationary linkage is arranged between the first axle and the third axle and the second stationary linkage is arranged between the second axle and the fourth axle. The first and a second stationary linkage are fixed to the stand. Both stationary linkages may be designed as integral part of the stand.

[014] The first and the second variable length guide is configured to change its length during use, wherein one end of each variable length guide is pivotally connected to the stationary linkage via the respective first and second axle. The variable length guide is configured so that rotation of one of variable length guides by some angle of rotation will cause the rotation of other variable length guide by the same angle, but in opposite direction.

[015] Each of the first and the second crank is pivotally connected to the respective third and fourth axle of the stationary linkage. [016] The connection rod connects the variable length guides and cranks, wherein one end of the connection rod is pivotally connected to the respective first variable length guide and the first crank via a first common pin and another end of the connection rod is pivotally connected to the respective second variable length guide and the second crank via a second common pin. The ratio of the crank length to the length of the connecting rod is equal to the ratio of the length of the stationary linkage (distance between the centres of the axles of the crank and the variable length guide) to the crank length.

[017] The antiparallelogram linkage mechanism further comprises a drive unit operatively connected to one of the first and the second crank or to one of the first and the second variable length guide to provide a rotation thereof. Therefore, the antiparallelogram linkage mechanism can be set in to movement by applying the torque moment to one of the said antiparallelogram linkage mechanism members. The variable length guide may be designed as a slider configured to change its length. In another embodiment, the variable length guide may be designed as a telescopic member configured to adjust its length. The variable length guide may be designed as any other mechanisms known to the skilled person, which is able to changes its length or distance between its two end points.

[018] The antiparallelogram linkage mechanism may be implemented into the wing drive mechanism. The proposed mechanishm of antiparallelogram linkage with the device for taking the antiparallelogram from the points of instability can also be used to desing a figure eight drive mechanism to move wings or blades of a vehicle moving in a liquid or gas medium. The wing drive comprises aforementioned antiparallelogram linkage mechanism, a wing, a transmission unit configured to transmit a movement of the connection rod of the antiparallelogram linkage mechanism to the wing, and an articulation means for mounting of the wing to the stand of the antiparallelogram linkage mechanism or to the body of the vehicle. The antiparallelogram linkage mechanism is mounted in the stand and the stand is arranged so that a plane of the antiparallelogram linkage mechanism is generally perpendicular to the spar of the wing. The transmission unit is pivotally connected to the connecting rod of the antiparallelogram linkage mechanism near the centre thereof.

[019] The wing drive mechanism is attached to flying vehicle body so that the wing drive mechanism is rotatable around an axis that is perpendicular or near perpendicular to the plane of the antiparallelogram linkage mechanism. In a so called figure eight wing driving mechanism (one example disclosed in US patent publication No. 4793573) antiparallelogram linkage with the device for taking the said mechanism from the points of instability is installed so that the antiparallelogram plane is near perpendicular to the wing spar. The wing spar is pivotally connected to the connecting rod of the parallelogram by the articulated member to transmit the figure eight movements of the center point of the connecting rod to the wing spar. The wing spar is pivotally mounted on the aircraft body or on the stationary linkage of the antiparallelogram. The antiparallelogram is mounted in the body of the vehicle motionlessly or with a possibility to rotate around the axis, which is near perpendicular to the mechanism’s plane. The vehicle may additionally comprise mechanism for controlling the angle of attack of the wing along the wing movement path.

[020] Based on the analogy between planar and spherical mechanisms as disclosed in publication of “V. V. Dobrovolsky's Contribution to Development of the Theory of Spherical Mechanisms. E.Ja. Antonuik, S.A. Khorosheva, National Academy of Sciences of Ukraine, S.P. Timoshenko Institute of Mechanics” it can be concluded that the antiparallelogram linkage mechanism with the device from taking said the mechanism from the points of instability can have embodiment as a spherical mechanism. In the following embodiment, a ratio of a length of the crank to a length of the connection rod differs from a ratio of a distance between the centres of the common axles as it is with a planar embodiment of the invention.

[021] The variable length guides may be designed by one-degree-of-freedom (prismatic joint) or two-degrees-of-freedom (cylindrical joint) kinematic pairs like rod and slider, straight slot with a pin, cylinder and piston. The kinematic link can be represented by pair of toothed gear wheels of the same dimension and module, each of which is connected with one of the said variable length linkages and has with it the common center of rotation. There are also other variants of the kinematic link design, e.g. in form of belt drive with a cross belt and pulleys of the same diameter, in which each of the said variable length links is attached to one of the said pulleys having a common center of rotation.

[022] The figures provided below give a detailed description of the invention.

[023] Fig. 1 is a theoretical kinematic scheme of antiparallelogram linkage mechanism.

[024] Fig. 2 is a kinematic scheme of antiparallelogram linkage mechanism. [025] Fig. 2A is a theoretical kinematic scheme of antiparallelogram linkage mechanism embodied on a spherical surface (spherical mechanism).

[026] Fig. 3 is one embodiment of the invention in perspective view from front.

[027] Fig. 4 is perspective view from back of the embodiment shown in Fig. 3.

[028] Fig. 5 is a kinematic scheme of embodiment as shown in Figs. 3 and 4.

[029] Fig. 6 is perspective view from one side of one embodiment of the wing drive mechanism.

[030] Fig. 7 is perspective view from another side of the embodiment shown in Fig. 6.

[031] Fig. 7A is a side view of the embodiment shown in Figs. 6 and 7.

[032] Fig. 8 is a kinematic scheme of the embodiment as shown in Figs. 6 and 7.

[033] Fig. 9 is a kinematic scheme of another embodiment of the wing drive mechanism.

[034] Fig. 10 is a kinematic scheme of another embodiment of the wing drive mechanism.

[035] Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.

[036] Fig. 1 is theoretical kinematic scheme of antiparallelogram linkage mechanism that proves that at any position of the said antiparallelogram the angles between the axis of the said stationary link and axes of the said variable length guides are equal in magnitude and opposite in direction.

[037] From the triangles AAiB and DDiC (see Fig. 1) according to the cosine rule we get l ² = r ² + c ² — 2 rc cos(n — a) = r ² + c ² + 2 rc cos a , and l ² = r ² + d ² — 2 rd cos a , and from here we get that cd = l ² — r ² . (1)

[038] From the triangles ABO and CDO according to the cosine rule we get l ² = a ² + a ₂ — 2 a ₁ a ₂ cos b. (2)

[039] From the triangles AiBO and CDiO according to the cosine rule and taking into account equation (2) we get nd from here we get that c ² + d ² = 21 ² — 2 ar + 2 r ² + 2ar cos b. (3) [040] Investigating the triangles ABAi and CDiD we get d — c = 2r cos a . (4)

[041] Expressing the length \AD\ trough the known values:

\AD I = a = r + c cos a + a cos b — (d cos a — r) = 2r — (d — c) cos a + a cos b and taking into account equation (4) we get cos b = 1 — 2 - asin ² a. (5)

[042] From the triangles A1A2B and CDD2 we get: c sin a + d sin a = a sin/5, from here we obtain

(d + c) ² = a 2 sin ² // sin ² a (6)

[043] From the equations (1), (3) and (6) we get:

[044] From there, taking into account equation (5) we get: l ² — r ² = 2 ra — l ² — r ² or

T

[045] Let y = l like in the case of the piston engine geometry, in this case we get that r = X ² a. (8)

[046] It can be shown from the expression (7) that the locations of the points Ai and Di can be found by dropping perpendicular lines from the point B and C correspondingly to the link AD when the mechanism is at the position so that the link BC crosses the link CD in its midpoint.

[047] Based on the above conclusion the relation between a, l and r for a spherical mechanism embodied on a sphere of radius R the expression for r can be written as:

[048] The same theoretical scheme of antiparallelogram linkage mechanism as shown in Fig. 1 is implementable as spherical mechanism illustrated in Fig. 2A, wherein the same mechanism is embodied on a spherical surface.

[049] Fig. 2 is a kinematic scheme of antiparallelogram linkage mechanism, wherein links AiB and DiC as shown in Fig. 1 are slide mechanisms in the form of a first variable length guide 7 and a second variable length guide 7a providing variable length thereof. The link BC as shown in Fig. 1 is as a connection rod 6. The links AB and CD as shown in Fig. 1 are respectively as a first crank 5a and a second crank 5a in Fig. 2. Fig. 2 also illustrates a torque moment or rotation w and -w. The axles Di, Ai, D, A as shown in Fig. 1 are respectively as a first axle 3, a second axle 3a, a third axle 33 and a fourth axle 33a in Fig. 2. The links DiD and AiA as shown in Fig. 1 are respectively as a first stationary linkage 4 and a second stationary linkage 4a in Fig. 2. Fig. 1 also illustrates a stand 1 wherein all four axles 3, 3a, 33, 33a lie in one plane with a common axis X of the stand 1 and are perpendicular to said common axis X.

[050] Figs. 3 and 4 is one embodiment of the invention comprising the stand 1, two identical covers 2 and 2a, having central holes equipped with internal splines, two identical axles 3 and 3a having external splines on the both ends, two identical stationary linkages 4 and 4a having holes equipped with internal splines, two identical cranks 5, 5a of the antiparallelogram linkage mechanism, the connecting rod 6, two identical variable length guides 7 and 7a and two identical toothed gear wheels 8 and 8a.

[051] The stand 1, the covers 2 and 2a, the axles 3 and 3a together with the stationary linkages 4 and 4a form the stationary link of the antiparallelogram linkage mechanism. The covers 2 and 2a are mounted in the holes in the stand 1 and secured with screws. The axles 3 and 3a are pairwise inserted with their first splined ends into the internal splines of the covers 2 and 2a and secured with screws. On the other ends of the axles 3 and 3a the stationary linkages 4 and 4a are pairwise mounted by means of the splined couplings, which are secured with a screw. The splines in the covers 2 and 2a, axles 3 and 3a, and stationary linkages 4 and 4a are arranged in such a way that the longitudinal axes of the stationary linkages 4 and 4a coincide with one another and are alligned on the common axis X joining the centers of the openings in the covers 2 and 2a or are parallel to the common axis X. The stationary linkages 4 and 4a are pairwise pivotally connected to the cranks 5 and 5a respectively. With the other end the cranks 5 and 5a are pairwise pivotally connected to the ends of the connection rod 6 and slotted guides 7 and 7a. The ratio of the length of the stationary linkages 4 or 4a (the distance between the axis of the pin and the axis of the slided opening in the said stationary linkage) to the length of the crank 5 or 5a is equal to the ratio of the length of the crank 5 or 5a to the length of the connecting rod 6 (see Figs. 3 and 4).

[052] The device for taking the antiparallelogram mechanism from the points of instability further comprises two toothed gear wheels 8 and 8a and two slotted guides 7 and 7a pairwise attached to the gear wheels 8 and 8a. The paths in the slotted guides 7 and 7a are oriented in radial direction. The slotted guides 7 and 7a are arranged so that in the points of instability of the antiparallelogram mechanism the axes of the slotted guides 7 and 7a coincide with one another and are parallel to the axis X joining the centers of the openings in the covers 2 and 2a (see Figs. 3 and 4).

[053] Fig. 5 is a kinematic scheme of embodiment as shown in Figs. 3 and 4.

[054] Figs. 6 and 7 and 7A illustrate embodiment of the wing drive mechanism. The stationary link of the antiparallelogram linkage mechanism comprises the outside panel 1, two covers 2 and 2a, two axles 3 and 3a and two stationary linkages 4 and 4a. The outside panel 1, an inside panel 9, four struts 10, an insert 20, two covers 2 and 2a and two covers 11 and 11a form the casing of the mechanism. The outside panel 1, the inside panel 9, the insert 20 and stmts 10 are fastened together with screws. The covers 2 and 2a are mounted in the holes in the external panel 1 and secured with screws. The covers 11 and 11a are mounted in the holes in the internal panel 9 and secured with screws. The axles 3 and 3a with their first splined ends are inserted into the internal splines in the covers 2 and 2a respectively and secured with screws. On the second ends of the said axles 3 and 3a the stationary linkages 4 and 4a are mounted by means of the splined coupling and secured with screws. The splines in the covers 2 and 2a, axles 3 and 3a and stationary linkages 4 and 4a are arranged in such a way that the longitudinal axes of the stationary linkages 4 and 4a coincide with one another and lie on the common axis X or are parallel to the common axis X that joins the centers of the openings in the covers 2 and 2a. The stationary linkages 4 and 4a positioned on the axles 3 and 3a respectively are pairwise pivotally connected to the cranks 5 and 5a. The cranks 5 and 5a, with the other ends, are pairwise pivotally connected to the ends of the connection rod 6 and slotted guides 7 and 7a. The ratio of the length of the stationary linkage 4 or 4a (the distance between the axis of the pin and the axis of the slided opening in the said stationalry crank) to the length of the crank 5 or 5a is equal to the ratio of the length of of the crank 5 or 5a to the length of the connecting rod 6.

[055] The gear wheels 8 and 8a are made integral with the hollow shafts. The shafts of the gear wheels 8 and 8a with one end are pairwise inserted into the cover 2 and 2a respectively and with the other end the shafts 8 and 8a are pairwise inserted into the holes in the covers 11 and 11a respectively. The axles 3 and 3a are passing through the hollow shafts of the gear wheels 8 and 8a respectively. The variable length links are represented by the slotted guides 7 and 7a and pins 57 and 57a joining cranks 5 and 5a with the connecting rod 6 and the said guides 7 and 7a. The slotted guides 7 and 7a have splined holes, by means of which they are mounted on the shafts of the gear wheels 8 and 8a respectively. The spline joints are secured with screws. The forked-end arm 16 is fixed to the root portion of the wing 12. The forked-end arm 16 in its middle portion is pivotally joined with the clevis fork 21, which has a pin, which is rotatably mounted in the top insert 20. The arm 16 with its forked tail is linked with the center of the connecting rod 6 by the articulated chain comprising an arm 13, a ball joint head 14 and a clevis bracket 15. The articulated chain is designed to transmit the movement of the center of the connection rod 6 through the articulated chain and the forked-end arm 16 to the wing 12. Swinging moment of the connection rod 6 is transferred as a reciprocating movement of the arm 13. The middle of the connection rod 6 describes a figure-eight shaped curve and this movement is transferred to the arm 13 via a ball joint 14 having enough freedom of movement to transfer figure-eight shaped movement to the reciprocating movement of the arm 13. The end of the arm 13 connected to the connection rod 6 follows the figure-eight shaped curve of the middle of the connection rod 6, but another end of the arm 13 connected to the forked-end arm 16 transfers this movement to the forked-end arm 16 and further to the wing 12. To set the wing driving mechanism into motion a torque moment is applied to the toothed gear wheel 8 through the driving gear wheel 17, which sits on the same shaft together with the toothed gear wheel 8 and is fixed to it. The driving gear wheel 17 receives the torque moment from the geared shaft 18, which one end represents the master gear wheel.

[056] The wing driving mechanism is mounted inside the body of the vehicle 22 by means of a housing axle 19, which is coaxial with the geared shaft 18 so that the whole mechanism may change its installation angle inside the body of the vehicle 22. The mechanism of changing the installation angle is not shown in the figure. The mechanism of changing the installation angle may be made by the means already known to the skilled person.

[057] Fig. 8 is a kinematic scheme of embodiment as shown in Figs. 6 and 7.

[058] In the Fig. 9 a kinematic scheme of another embodiment of the mechanism is shown. The embodiment in the Fig. 9 is characterized in that the torque moment is applied directly to the driving crank 5 of the antiparallelogram linkage. The following changes have been made in the embodiment shown in Fig. 9 compared to the embodiment shown in Fig. 8: - the first crank 5 has been replaced by the first crank 5 and a third crank 5b and the second crank 5a has been replaced by the second 5a and a fourth crank 5c. The lengths of the cranks 5, 5a, 5b and 5c are equal;

- the stationary linkage 4 has been replaced by a linear displacement of the centers of the covers 2 and 11, and the stationary linkage 4a has been replaced by a linear displacement of the covers 2a and 11a;

- the first crank 5 is firmly attached to one end of the third axle 33 and the second crank 5b is firmly attached to the other end of the third axle 33. Respectively the second crank 5a is firmly attached to one end of the fourth axle 33a and the fourth crank 5c is firmly attached to the other end of the fourth axle 33a.The axis of the first crank 5 is parallel to the axis of the third crank 5b, and the axis of the second crank 5a is parallel to the axis of the fourth crank 5c;

- the first crank 5 is pivotally connected to one end of the connecting rod 6 and the second crank 5a is pivotally connected to the other end of the connecting rod 6;

- the pin 57b of the third crank 5b is sliding in the path of the first slotted guide 7 and the pin 57c of the fourth crank 5c is sliding in the path of the second slotted guide 7a; and

- the driving gear wheel 18 is firmly mounted on the third axle 3b to transmit the torque moment to the driving crank 5.

[059] In another embodiment as seen in Fig. 10, the wing 12 and the arm 13 are positioned on the same side in relation to the body of the vehicle 22. This arrangement allows to position the wing 12 in opposite direction compared to the previously described embodiments of the invention (see Figs. 6 to 9).

[060] While particular embodiments of the invention have been shown and described, numerous variations alternate embodiments will occur to those skilled in the art.