Machine element or mechanism – Mechanical movements – Rotary to rotary
Reexamination Certificate
2000-04-03
2001-05-15
Herrmann, Allan D. (Department: 3682)
Machine element or mechanism
Mechanical movements
Rotary to rotary
C074S053000, C074S569000, C074S834000
Reexamination Certificate
active
06230575
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a gear transmission with stepless adjustable translation ratio for converting rotational speeds and torques between two shafts.
2. Brief Description of the Background of the Invention Including Prior Art
Such converters represented by gear transmissions with stepless adjustable translation are employed in the complete motive power engineering, in particular in connection with machine tools as with vehicle engines.
Such a gear transmission is known as a variation of ratchet gear or ratchet mechanism drives from the German patent 474205. A gear transmission is proposed there, wherein the rotational motion of the drive shaft is transformed by way of several cam disks disposed on the driving shaft into a back and forth motion of push rods and by intermediate positioning of a variable translation device into a back and forth motion of gear racks, wherein the gear racks in the following successively operate on the driven shaft and drive the driven shaft through gear wheels and blocking couplings (free engine clutch). The variable translation device comprises a two armed lever with adjustable hinge point for changing the in each case effective lever lengths and thus also transmission ratio size. The gear racks move with uniform speed during the force transmission phase and are thus able to drive the driven shaft with a uniform angular speed. The motion transfer in the device according U.S. Pat. No. 4,565,105 occurs in a similar way.
A substantial deficiency of such gear transmission systems comprises that the wear appearances occurring during the transforming of the translational motion into a rotational motion of the driven shaft, for example, the back and forth motion of the gear racks to a rotational motion of the gear wheel in the gear rack/gear wheel drive, are of substantial size in particular in continuous operation and can interfere substantially with the reliability of the overall gear transmission. The wear appearances concern in particular those regions of the toothed wheel work of the gear rack and gear wheel, which are subjected more frequently to a particularly large mechanical load during the periodical loading in continuous operation as compared to other regions. However the wear occurring also upon employing cam drive gear mechanisms as a second force transmission means in the regions between engagement members and cam members and their guide tracks or, respectively, between engagement members is not negligible. The non-uniform distribution of the material abrasion by wear based on the non-uniform load of the stroke distance available of the gear rack or, respectively, of the engagement member is further increased in that the force to be transmitted increases, based on the increase of the translation setting (decrease of the length of the stroke distance) under the condition of constant transmission power. The strong and in particular also non-uniform wear at the function determining contact faces of the gear transmission elements of the second force transmission means transferring the motion is, however, associated with deviations from the desired relative motion of the gear transmission means, which in turn are the cause for a rapidly advancing wear process.
SUMMARY OF THE INVENTION
1. Purposes of the Invention
Therefore it is an object of the present invention to furnish a gear transmission with continuously changeable translation ratio with a transmission of the motion as uniform as possible, wherein the reliability and the operational life of the overall gear transmission can substantially be increased by a substantially decreased wear at function determining contact faces, in particular of the driven side gear transmission part system (second force transmission means).
These and other objects and advantages of the present invention will become evident from the description which follows.
2. Brief Description of the Invention
The present invention allows a uniform transfer of motion from the drive shaft to the driven shaft. It is characterized by substantially reduced wear occurrences at function determining gear transmission elements. The steplessly adjustable gear transmission comprises at least two staggered operating gear transmission units, which transfer the rotational motion of the drive shaft intermittently for in each case a time period (force transmission phase) onto the driven shaft. The uniform rotational motion of the drive shaft in each gear transmission unit is here transformed in the force transmission phase by a first force transmission means into a first uniform translational motion, this motion is transformed into a second uniform translational motion (stroke) with a speed depending on the translation setting by a changeable translation device (
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) and this translational motion (stroke) is transformed into a uniform rotational motion by the second force transmission means, wherein the uniform rotational motion in turn can be transmitted to the driven shaft by an automatic switching or switching coupling.
The transmission gear with the steplessly adjustable translation comprises a drive shaft, a driven shaft, at least a first gear transmission unit and a second gear transmission unit.
The first gear transmission unit includes a first force transmission means wherein the first force transmission means transforms a first uniform rotary motion of the drive shaft into a first uniform translation motion during a first force transmission phase, a first changeable translation device, wherein the first changeable translation device converts the first uniform translation motion into a second uniform translation motion with a speed depending on the translation setting during the first force transmission phase while the translation setting is maintained at a constant value, and a second force transmission means and wherein the second force transmission means transforms the second uniform translation motion into a second rotary uniform motion during the first force transmission phase while the translation setting is maintained at a constant value.
The second gear transmission unit includes a third force transmission means wherein the third force transmission means transforms the first uniform rotary motion of the drive shaft into a third uniform translation motion during a second force transmission phase, a second changeable translation device, wherein the second changeable translation device converts the third uniform translation motion into a fourth uniform rectilinear motion with a speed depending on the translation setting during the second force transmission phase while the translation setting is maintained at a constant value, and a fourth force transmission means and wherein the fourth force transmission means transforms the fourth uniform translation motion into a third uniform rotary motion while the translation setting is maintained at a constant value during the second force transmission phase.
Switching or automatic switching couplings are employed, wherein the switching or automatic switching couplings transfer the second uniform rotary motion and the third uniform rotary motion to the driven shaft. Additional means shift the region used for the second uniform translation motion within the complete stroke distance usable for the second translation motion of the second force transmission means and shift the region used for the forth uniform translation motion within the complete stroke distance usable for the fourth translation motion of the fourth force transmission means during the running of the transmission gear with a speed influencing the driven motion only unsubstantially, wherein the rotary motion of the drive shaft is sequentially and intermittently transferred to the driven shaft by the first gear transmission unit and, respectively, by the second gear transmission unit for in each case a respective time interval during a respective force transmission phase.
The first changeable translation device can comprise a translation set unit including a threaded s
Herrmann Allan D.
Kasper Horst M.
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