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Title:
INTERCONNECTING MECHANISM
Document Type and Number:
WIPO Patent Application WO/1996/023990
Kind Code:
A1
Abstract:
A mechanism is disclosed for interconnecting a rotary component (32) and two members (25, 26) linearly reciprocable at 90� to each other in respective bores (16, 18, 17, 19) in a housing (15). The first rotary component (32) has a shaft (33) with an eccentric surface (34). A second rotary component (36) has a bore (37) in which is received surface (34), and first and second eccentric surfaces (37 and 38), the eccentric surfaces (34, 37 and 38) all having the same throw. Each reciprocable member (25) has a pair of spaced-apart pistons (26, 27) with a web (28) extending therebetween, the web having a bore (29) in which is received the first (or second) eccentric surface (38 or 39). In operation, the first and second rotary components (32 and 36) contra-rotate, and the first and second members (25) reciprocate linearly 90� out of phase with each other.

Inventors:
OSBORNE GRAHAM WILLIAM (GB)
Application Number:
PCT/GB1996/000210
Publication Date:
August 08, 1996
Filing Date:
January 31, 1996
Export Citation:
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Assignee:
OSBORNE GRAHAM WILLIAM (GB)
International Classes:
F16H21/36; (IPC1-7): F16H21/36
Foreign References:
DE883540C1953-07-20
US4173151A1979-11-06
FR1319313A1963-03-01
CH231110A1944-02-29
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Claims:
CLAIMS
1. A mechanism for interconnecting a rotary component and at least two linearly reciprocable members, which mechanism comprises: a first rotary component including an external first eccentric surface arranged eccentrically with respect to the axis of said first component; a second rotary component including a bore and external first and second further eccentric surfaces, said first eccentric surface being received in the bore, the first and second further eccentric surfaces being arranged eccentrically with respect to the axis of the bore but with their throws at 180° to each other, and the eccentricities of the first eccentric surface, first further eccentric surface and second further eccentric surface all being essentially the same; a first reciprocable member having a bore in which is rotatably received the first further eccentric surface; a second reciprocable member having a bore in which is rotatably received the second further eccentric surface; means to constrain movement of the first reciprocable member along a first linear path normal to the axis of the first rotary component; and mean s to cons train movement of the s e cond reciprocable member along a linear path mutually at rightangles to the axis of the first rotary component and to the l inear path of movement of the f irst reciprocable member.
2. A mechanism as claimed in claim 1, wherein the means to constrain the first and second reciprocable members to move along their respective linear paths comprises a body in which said members are slidably mounted.
3. A mechanism as claimed in claim 2, wherein each of the first and second reciprocable members defines a respective piston which is slidably mounted within an associated bore in the body.
4. A mechanism as claimed in claim 3, wherein each of the first and second reciprocable members defines a respective pair of pistons with the associated bore receiving the respective second eccentric surface formed between the pistons of that pair, the two pistons of each member being slidably mounted within associated aligned bores in the body.
5. A mechanism as claimed in any of claims 2 to 4, wherein the first rotary component includes a shaft on which the first eccentric surface is mounted, the shaft being rotatably mounted in the body.
6. A mechanism as claimed in any of claims 3 to 5, wherein each of the first and second reciprocable members is in the form of a pair of spaced pistons with a connecting web extending therebetween, the bore for the second eccentric surface being formed in the web.
7. A mechanism as claimed in any of the preceding claims, wherein the axes of linear movement of the first and second reciprocable members are spaced along the axis of the rotary component.
8. A mechanism as claimed in claim 1 or claim 2, wherein the first rotary component includes a shaft on which the first eccentric surface is mounted.
Description:
INTERCONNECTING MECHANISM

This invention relates to a mechanism for interconnecting a rotary component and at least one linearly reciprocable member.

There has been a great number of proposals for mechanisms arranged to interconnect a rotary component and at least one linearly reciprocable member, whereby rotation of the component causes the member to reciprocate, or reciprocation of the member causes the component to rotate. The simplest of such mechanisms comprises a rotatable crank linked by a connecting rod to the reciprocable member which, in the case of a reciprocating piston engine or pump, comprises a piston sliding within a cylinder. The connecting rod is journalled one end to the crank and at its other end to the piston, or to a piston rod in turn connected to the piston. Such an arrangement is very widely employed, but has the disadvantage that the piston movement is a complex function of connecting rod length; the piston movement is only truly sinusoidal with a connecting rod of infinite length.

An alternative interconnecting mechanism comprises an eccentric device. Here, a disc (the "eccentric") is mounted eccentrically on a shaft and an eccentric strap fits slidingly therearound, the eccentric strap being linked to the reciprocable member by a connecting rod rigidly secured at one end to that strap. Movement of the member again is only truly sinusoidal with an infinitely long connecting rod.

True sinusoidal member reciprocation may be achieved with a mechanism including rotatable component having a pin which follows a circular locus and running in a slot provided in the reciprocable member, with the slot extending at right angles to both the direction of reciprocation and axis of rotation. It is however difficult to manufacture such a mechanism without

introducing relatively large clearances and so significant backlash. Though there are innumerable other mechanisms for linking a rotatable component and a reciprocable member, mention here may be made of the Maltese Cross mechanism, wherein up to four reciprocable members, arranged in a cross-like formation, are caused to reciprocate by means of a respective pin on each member engaging in a curved cam surface formed on the rotatable component. Such a mechanism does not smoothly and continuously drive the reciprocable members and can be operated only relatively slowly.

The present invention aims at providing an interconnecting mechanism for at least one linearly reciprocable member, but possibly up to four such members, which mechanism may be smoothly-operating and have a predictable function for the linear movement of the or each reciprocable member relative to component rotation. According to the present invention, there is provided a mechanism for interconnecting a rotary component and at least tow linearly reciprocable members, which mechanism comprises:

- a mechanism for interconnecting a rotary component and at least two linearly reciprocable members, which mechanism comprises:

- a first rotary component including an external first eccentric surface arranged eccentrically with respect to the axis of said first component; - a second rotary component including a bore and external first and second further eccentric surfaces, said first eccentric surface being received in the bore, the first and second further eccentric surfaces being arranged eccentrically with respect to the axis of the bore but with their throws at 180° to each other, and the eccentricities of the first eccentric

surface, first further eccentric surface and second further eccentric surface all being essentially the same;

- a first reciprocable member having a bore in which is rotatably received the first further eccentric surface;

- a second reciprocable member having a bore in whi c h i s rotatab ly rece ived the s e cond f u rther eccentric surface; - means to con s trai n movement o f the f ir s t reciprocable member along a first linear path normal to the axis of the first rotary component; and

- means to con s trai n movement o f the s e cond reciprocable member along a linear path mutually at right-angles to the axis of the first rotary component and to the l i near path of movement o f the f i rs t reciprocable member .

The mechanism of this invention may be regarded as a double-eccentric mechanism, wherein a first eccentric has a pair of second eccentrics mounted thereon, rather than a conventional eccentric strap. Then, the second eccentrics are directly coupled to the respective first and second reciprocable members, whereby rotation of the first rotary component in one sense causes rotation of the second rotary component in the other sense and the action of both rotary components causes linear sliding movement of the two reciprocable members. Conversely, reciprocation of the two reciprocable members will cause rotation of both the second and first rotary components, but in opposite senses, whereby a rotary output is obtained from the first rotary component of mechanism.

The "throw" of the first and both further eccentric surfaces must all be the same - that is to say, the eccentricity of the first eccentric surface with respect to the axis of the first component must be

equal to the eccentricity of the first and second further eccentric surfaces with respect to the axis of the bore of the second rotary component. In this way, the stroke of the reciprocable members will be equal to four times that eccentricity (or throw) of each eccentric surface. This is because in one extreme position of a reciprocable member, the eccentricities of the first and second rotary components are aligned and additive, and at the other extreme of travel of the reciprocable member, the eccentricities are again aligned and additive but in the opposite sense. These positions correspond to rotation of the first rotary component through 180°. At the intermediate 90° and 270° positions of the first rotary component, the eccentricities of the first and second rotary components are aligned, but subtractive; in these positions, the geometric centre of the bore of the first reciprocable member lies on the axis of rotation of the first rotary component. In a preferred form of the mechanism of this invention, the first reciprocable member includes a piston slidably arranged within a cylinder. Most preferably, however, the first reciprocable member has two pistons arranged one to each side respectively of the bore in that member, each of which pistons slides in an associated cylinder, the two cylinders being arranged coaxially. In either case, the reciprocable member is constrained to follow a linear path by the cylinder. The second reciprocable member may be configured similarly to the first reciprocable member and thus may include a pair of pistons, one to each side respectively of the bore in the second reciprocable member, and arranged for sliding movement in a pair of associated cylinders, arranged coaxially. These cylinders will have their common axis at right angles

to the axis of the cylinders of the first reciprocable member. In order to allow the construction of such a mechanism, the first and second external further eccentric surfaces must be spaced axially on the second rotary component. Preferably, the axes of the associated cylinders are similarly displaced along the axis of the first rotary component, though it would be possible to arrange for the cylinder axes to be in the same plane, with the pistons offset with respect to the respective reciprocable members.

In a preferred construction, the mechanism includes a body in which are formed the respective cylinders and the first rotary component includes a shaft on which the first eccentric surface is provided, the shaft being rotatably mounted in the body. The first and second reciprocable members each may comprise a pair of spaced pistons with a connecting web extending therebetween, the bore for the second eccentric surface being formed in that web. In this way, a particularly compact mechanism may be constructed, wherein the movement of each piston is truly sinusoidal, with respect to angular displacement of the first rotary component.

By way of example only, one specific embodiment of interconnecting mechanism constructed and arranged in accordance with the present invention will now be described in detail, reference being made to the accompanying drawings, in which :-

Figure 1 is a diagrammatic cross-sectional view through the mechanism, on the axis of the first rotary component;

Figures 2 and 3 are diagrammatic sectional views of the mechanism, taken respectively on lines II-II and III-III marked on Figure 1; Figures 4A, 4B and 4C are respectively plan, end and side views of the first reciprocable member used

in the mechanism, the second reciprocable member corresponding;

Figures 5A and 5B are respectively side and end views of the first rotary component; Figures 6A and 6B are respectively side and end views of the second rotary component;

Figures 7A, 7B and 7C are respectively a cross- section through the body component and sections on lines X-X and Y-Y marked on Figure 7A; Figures 8, 9, 10 and 11 show further positions for the mechanism, starting from the position shown in Figure 1, to a position where the first rotary component (Figures 5A and 5B) has turned through 180°; and Figure 12 diagrammatically shows a further embodi¬ ment of interconnecting mechanism of this invention.

The embodiment of interconnecting mechanism of this invention, as shown in the drawings, comprises a body 15 which defines four cylinders 16, 17, 18 and 19 arranged in two coaxial pairs 16,18 and 17,19. The axis 20 of cylinders 16,18 extends in a direction normal to axis 21 of cylinders 17,19 and is displaced laterally with respect thereto. The body 15 also defines a pair of journals 22 and 23 the common axis 24 of which extends mutually at right angles to axes 20 and 21, both of which axes intersect axis 24.

A first reciprocable member 25 (see particularly Figures 4A, 4B and 4C) has a pair of pistons 26,27 rigidly interconnected by means of a web 28. A bore 29 is formed through the web 28, midway between the pistons 26,27 the bore axis intersecting the common axis of the pistons. The first reciprocable member 25 is mounted in the body 15, with the pistons 26,27 slidingly received in the cylinders 16,18 whereby the first reciprocable member is constrained for sliding movement along axis 20. A second reciprocable member

30 is similarly configured to the first reciprocable member and is mounted in the body 15 with its pistons arranged for sliding movement in cylinders 17 and 19 respectively. By virtue of the relatively narrow webs of the reciprocable members, those members may perform simultaneous reciprocation with a limited stroke.

A first rotary component 32 (Figures 5A and 5B) comprises a shaft 33 carrying an eccentric 34, the axial length of the eccentric 34 exceeding slightly the spacing of the axes 20 and 21 of the cylinders in the body. The eccentric 34 has an eccentricity e, with respect to the shaft 33. The shaft itself is carried in the journals 22, 23 whereby the shaft 34 and its eccentric 34 may rotate within the body 15. A second rotary component 36 (Figures 6A and 6B) has a bore 37 which is rotationally carried on the eccentric 34 of the first rotary component, the second rotary component defining two further eccentrics 38 and 39, arranged with their respective throws 180° out-of- phase. The eccentricities of these two further eccentrics 38 and 39 are each equal to the eccentricity e of the eccentric 34. The axial spacing of the two further eccentrics 38 and 39 is equal to the separation of the axes 20 and 21 of the cylinders in the body 15. When fully assembled as shown in Figure 1, the shaft 33 is carried in journals 22 and 23 of the body; the bore 37 of the second rotary component is carried by the eccentric 34 of the first rotary component 32; and the two further eccentrics 38 and 39 are respectively received in the bores 29 of the first and second reciprocable member 25 and 30. Figure 1 shows the second reciprocable member 30 at one (upper, in the drawing) extreme of its travel in cylinders 17 and 19, with the first reciprocable member 25 at precisely the mid-point of its travel, between its two extremes, in cylinders 16 and 18. In this position, the

eccentricities of the eccentrics 34 and 38 are aligned and additive in the direction of axis 21; and the eccentricities of eccentrics 34 and 39 are also aligned but subtractive in that same direction and so the axis of eccentric 39 lies on axis 20, of cylinders 16 and 18. The first reciprocable member 25 is thus at its mid position.

Starting from the position shown in Figure 1, the first rotary component 32 may be turned in a counter- clockwise direction as illustrated by arrow A, in which case the second rotary component rotates in the clockwise direction, arrows B and C showing the rotations of the further eccentrics 38 and 39 respectively. From that starting position. Figure 8 shows an intermediate position and Figure 9 the position with the first rotary component 32 turned through 90°. Here, the first reciprocable member 25 is at its extreme leftward movement and the second reciprocable member 30 is at its mid-position, with the respective eccentrics now being aligned along axis 20. Continued counter-clockwise rotation of the first rotary component 32, in the direction of arrow A, results in the components passing through the relative positions shown in Figure 10 to the position shown in Figure 11, where the eccentrics are once more aligned along axis 21, but this time with the second reciprocable member 30 at its other extreme (lower, in the drawing) position. Again, the first reciprocable member 25 is at its mid-position. From there, continued rotation of the first rotary component 32 eventually takes the various parts back to the position shown in Figure 1.

Though described above as rotation of shaft 33 producing reciprocating movement of the pistons 26 and 27 of the first and second reciprocable members 25 and 30, it will be appreciated that the mechanism may

operate in the opposite sense - that is to say, the pistons of the reciprocable members may be driven, and the shaft 33 will then be rotated.

The mechanism described above is arranged with two pairs of pistons, the axes of the two pairs being at 90° to each other. The mechanism could have only two pistons arranged in a Vee format with an included angle of 90° between the axes of the pistons. Also, more than one assembly may be provided along the axis of the main shaft. For example, two assemblies as shown in Figures 1 to 11 may be stacked axially, in effect providing a four cylinder configuration. Figure 12 shows a four piston arrangement and in this drawing parts common with those of the preceding embodiment are given like reference characters but suffixed with A or B, as appropriate. In this arrangement, the two pairs of pistons are disposed in pairs with an included angle of 90° between each pair. The eccentrics 38A and 39A are arranged 180° out of phase with the eccentrics 38B and 39B, with the eccentrics 38A and 38B mounted on a common shaft 33. Each pair of pistons 26A, 27A and 26B, 27B works exactly as has been described above in relation to Figures 1 to 11: consequently no further description thereof is included here.

The mechanisms illustrated in the drawings are diagrammatic, and the mechanism of Figures 1 to 11, as illustrated, could not in fact be assembled. However, the drawings illustrate the principles of the mechanism and only detail designing work is required in order to produce a practical mechanism. For example, it may be necessary to provide two or more split-lines for the body 15 whereby the body may be separated to allow the assembly of the various rotary components and reciprocable members, the body part then being assembled and bolted together. Also, it will be

appreciated that the cylinders 16-19 here merely serve as guides for the first and second reciprocable members 25 and 30. Other forms of guide could be provided. Equally, fluid-tight seals may be provided between the pistons and their respective bores, whereby the mechanism may serve as a pump, for example, with appropriate cylinder heads, valve-gear and so on. Equally, the mechanism could operate as a reciprocating piston internal combustion engine.