Machine element or mechanism – Control lever and linkage systems – Multiple controlling elements for single controlled element
Patent
1995-07-10
1996-11-19
Herrmann, Allan D.
Machine element or mechanism
Control lever and linkage systems
Multiple controlling elements for single controlled element
74417, 7449005, 475336, 901 26, B25J 1700, F16H 128
Patent
active
055751792
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a differential-type compact gear. It is designed to achieve, within a small space, a high gear ratio between an ingoing drive shaft and an outgoing main shaft which is rotatable between two end positions. The gear is especially suited for use with industrial robots.
BACKGROUND ART
To achieve high gear ratios in the range of between 1:50 and 1:150 or higher, gear units with many toothed wheels or other types of relatively space-demanding gear means are normally required. In many kinds of operation where only a small space is available, for example in articulated robot arms, this is an awkward drawback. The present invention relates to a gear unit which is built into a small space around the outgoing main shaft of the gear.
From U.S. Pat. No. 1,802,112, a differential-type reduction gear is previously known, by means of which very high gear ratios can be obtained. A drawback of this gear is that it comprises eight toothed wheels, which entails a high production cost and a large space requirement.
SUMMARY OF THE INVENTION
The invention relates to a compact gear comprising a gear housing and an outgoing main shaft which is rotatable in relation to the gear housing. The gear housing supports a motor with a drive shaft projecting into the gear housing. On the drive shaft there are arranged a first larger and a second smaller conical toothed wheel as well as a cross shaft, extending transversely through the main shaft and rotatably journalled in the main shaft. On each side of this cross shaft, two equally large first and second crown wheels are rotatably mounted on the main shaft and adapted to engage, on opposite sides, with a third conical toothed wheel mounted on the cross shaft. A third crown wheel with larger diameter than the second crown wheel is rotatably arranged around the main shaft and secured to the second crown wheel. The invention is characterized in that the drive shaft is arranged so as to form an angle with a normal plane of the main shaft, that the above-mentioned second smaller conical toothed wheel is arranged in engagement with the first crown wheel whereas the first larger conical toothed wheel in a known manner is arranged in engagement with the third crown wheel. The gear ratio between the second conical toothed wheel and the first crown wheel is different from the gear ratio between the first conical toothed wheel and the third crown wheel.
The invention provides a compact gear with few intermediate shafts since the outgoing main shaft at the same time constitutes the shaft of the crown wheels. The gear ratio between the ingoing drive shaft and the outgoing main shaft becomes greater the smaller the difference in speed of rotation is between the first and second crown wheels. This in turn means that the smaller the difference in gear ratio between the second conical toothed wheel and the first crown wheel in relation to the gear ratio between the first conical toothed wheel and the third crown wheel, the greater is the total gear ratio of the gear. Gear ratios up to and above 1:150 can be obtained in connection with the gear sizes which occur in, for example, robots.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a cross section of the gear housing with toothed wheels enclosed therein.
FIG. 2 is a schematic view of a robot with a compact gear. One leg of the robot stand is cut away in order to show the compact gear with the motor.
FIG. 3 is a detailed view of the same robot seen from the side with both legs of the stand in place.
DESCRIPTION OF THE PREFEREED EMBODIMENTS
In FIG. 1, 1 designates the gear housing and 2 a drive motor with adjustable speed up to about 3500 r.p.m. The motor 2 has a drive shaft 3 which projects into the gear housing 1. A main shaft 4 extends right through the gear housing 1. In the embodiment this main shaft is made so thick as to be able to support the gear housing 1, the motor 2 and a robot arm 5 mounted on the gear housing. On the drive shaft 3 of the motor 2 a first larger conical toothed wheel
REFERENCES:
patent: 1802112 (1931-04-01), Henderson et al.
patent: 2376900 (1945-05-01), Case
patent: 4047448 (1977-09-01), Pardo et al.
patent: 4068536 (1978-01-01), Stackhouse
patent: 4499790 (1985-02-01), Helms
Asea Brown Boveri AB
Herrmann Allan D.
LandOfFree
Compact gear does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Compact gear, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Compact gear will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-533200