The invention relates to a transmission as generically defined by the preamble to claim 1 or by the preamble to claim 2.
Transmissions of the aforementioned type are described for instance in international patent disclosure WO 95/22017. Such a transmission has a hollow-cylindrical main body with end faces that is provided with an internal toothing and has a rotary axis. In the main body, a driven input member and an output member are supported rotatably about the rotary axis. The output member includes two spaced-apart rotary bodies, with a circular cross section transversely to the rotary axis. The rotary axis is perpendicular to the two rotary bodies. The rotary bodies can be or are connected fixedly to one another. At least one gear wheel that meshes with the inner gear wheel, as well as means for converting planetary motions of the gear wheel into rotary motions of the output member (also called “converting means” or “conversion means”), are disposed between the rotary bodies. These converting means or conversion means for converting planetary motions of the gear wheel into rotary motions of the output member have a central opening through which the input member is passed, and four arms facing one another in pairs and uniformly distributed in the form of a cross around the central opening. The input member is supported on both sides in the rotary bodies of the output member, and the output member is in turn supported on both sides in the hollow-cylindrical main body.
Such transmissions have a disadvantage in that the conversion means, which in simplified terms are in the form of a cross, can only be manufactured after major technical effort and expense. Moreover, the force distribution inside the cross is unfavorable during torque transmission to the output member, which occurs simultaneously with the conversion of the planetary motion into rotary motion. This is especially so with regard to the incident forces because this is an “open” system.
According to international patent disclosure WO 2007/135540 A2, transmissions with adjustable torque transmission during operation are known. For that purpose, each of the transmissions has at least one fixed wheel split into two axially spaced parts, around which a belt is laid whose length is greater than the circumference of the wheel. A satellite wheel is disposed between the two parts of the fixed wheel. The satellite wheel has a different diameter from the fixed wheel. One input member and one output member are disposed coaxially to a rotary axis. The input member has at least one portion which has an adjustable eccentricity and on which at least one satellite wheel is disposed. Rotation of the input member causes the satellite wheel to roll on the inside face of the belt. With increasing eccentricity, the friction between the satellite wheel and the belt increases, so that a higher torque is transmitted. The conversion of the planetary motion of the satellite wheel into a rotary motion of the output member happens in various ways, depending on the design of the transmission:                If only one satellite wheel is provided, the output member comprises a rotary body disposed on one side of the satellite wheel. In that case, an annular conversion means can be provided between the satellite wheel and the output member. Both end faces of the ring then each have two guide means with center axes. The center axes of the guide means on one end face extend perpendicular to an axial plane, while the center axes of the guide means on the other end face extend parallel to the axial plane.        If two or more satellite wheels are provided, the output member comprises two rotary bodies, connected to one another by means of spacers and spaced axially apart from one another in the direction of the rotary axis. In that case, the satellite wheels move phase-offset by 180°, and the conversion of the planetary motions into a rotary motion of the output member is effected directly via the spacers. To that end, the spacers are guided through eccentric openings in the satellite wheels. Each of the spacers, in every opening it passes through, has constant linear contact, in every configuration, with the respective satellite wheel.        
This last manner of converting planetary motions into rotary motions is generally known, for instance, from patent disclosures U.S. Pat. No. 1,767,866, EP 0 474 897 A1, EP 1 816 374 A1, U.S. Pat. No. 3,129,611, and PL 169808, as well as in transmissions which, as described at the outset, have an output member which comprises two rotary bodies, connected to one another by means of spacers and spaced apart axially from one another in the direction of the rotary axis, and at least one gear wheel, disposed between the rotary bodies, which meshes with an internal toothing and executes planetary motions. It is also known in transmissions that have an output member that comprises only one rotary body with pins disposed eccentrically on it, which pins extend in the axial direction of the rotary axis and protrude into eccentric openings in one or more gear wheels, offset axially from the rotary body, that mesh with an internal toothing and execute planetary motions. Each spacer or pin, in every opening it passes through, always and in every configuration has constant linear contact with the respective gear wheel.
From French patent disclosure FR 797 130 A, a transmission with a variable gear ratio and a transmission with a fixed gear ratio are known. Each of the two transmissions has a housing with a rotary axis, and with an input and output member, both disposed in the housing rotatably about the rotary axis. The input member has an eccentric portion on which a gear wheel is disposed. The gear wheel meshes with an internal toothing disposed in the housing. Rotation of the input member causes the gear wheel to execute a planetary motion. The output member comprises a rotary body disposed on one side of the gear wheel. Conversion means for converting planetary motions into rotary motions of the output member are disposed between the rotary body of the output member and the gear wheel. The conversion means comprise a ring. Each of the two end faces of the ring has two guide means with center axes. The center axes of the guide means of one face end extend perpendicular to an axial plane, while the center axes of the guide means of the other face end extend parallel to the axial plane. A gear ring with an external toothing and an internal toothing is disposed, rotatably supported about the rotary axis in the housing of the transmission that has the variable gear ratio. A worm, which meshes with the external toothing of the gear ring, extends into the housing. The worm can be driven at a variable speed by an electric motor, and the gear ratio between the input member and the output member varies with the speed.
From Japanese patent disclosure JP 1 143 171, transmissions with a variable gear ratio are known. The transmissions have a housing with a rotary axis and an input and output member, both of which are disposed rotatably about the rotary axis in the housing. The input member has at least one eccentric portion, on which at least one gear wheel is disposed. The gear wheel meshes with an internal toothing. The internal toothing is located in a rotatably supported bell disposed in the housing. The bell can be driven at a variable speed. With the speed, the gear ratio also varies. The output member comprise a rotary body disposed on one side of the at least one gear wheel. Both end faces of the ring each have two guide means with center axes. The center axes of the guide means of one face end extend perpendicular to an axial plane, while the center axes of the guide means of the other face end extend parallel to the axial plane. In a transmission with two gear wheels that, upon a 180° rotation of the input member execute phase-offset planetary motions, the gear wheels have eccentric openings. Pins extending in the axial direction of the rotary axis pass through these openings and are disposed eccentrically on the rotary body that is disposed on one side of the gear wheels. In each eccentric opening that it passes through, and in every configuration, each pin always has linear contact with the respective gear wheel.
In the known transmissions, there is a disadvantageous in that their construction allows for only a limited load, because                they have only one rotary body as an output member, to which a torque is transmitted unilaterally with or without the aid of a conversion means for converting planetary motions of the gear wheel into rotary motions of the output member;        while they have two rotary bodies connected to one another and are axially spaced apart from one another by spacers, the torque transmission, with simultaneous conversion of the planetary motion of the wheels disposed between the rotary bodies into a rotary motion of the output member, is still effected directly by the wheels via the spacers; or        the conversion means in the form of a cross are provided between the gear wheel and the output member, and these means form an open system with regard to the forces that occur when a torque is transmitted.        
With the above prior art as the point of departure, it is the object of the invention to provide a remedy for these disadvantages.
The stated object is attained by the features of claim 1 and the features of claim 2.