Rotary expansible chamber devices – Interengaging rotating members – Like rotary members
Reexamination Certificate
2002-06-07
2004-03-23
Denion, Thomas (Department: 3748)
Rotary expansible chamber devices
Interengaging rotating members
Like rotary members
C418S171000, C074S462000
Reexamination Certificate
active
06709250
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a gear, more particularly, to the gear which has at least one longer tooth, shorter teeth and transition teeth.
In addition, the present invention relates to a fluid machine more particularly, to the fluid machine for conveying, compressing or expanding liquid or gaseous fluids, which has at least one gear pair according to the present invention.
PRIOR ART
In the prior arts in addition to be widely used as driving force transmission, the gear can also be used in many other fields. For example, a pair of gear-shaped rotors can be used as a gear pump to transport liquid fluids. However, the effective area used for fluid transferring by the rotors of the gear pump is relatively small, so the pumping efficiency is kept low. U.S. Pat. No. 3,574,491 discloses a gear-type rotary machine for transporting liquid fluid and compressing or expanding gaseous fluids, which consists of a housing and two engaging gear-shaped rotors being accommodated in the housing. Each gear includes two sets of shorter teeth alternating with one or more longer teeth. Because the two engaging gear-shaped rotors are provided with longer teeth, the effective area used for fluid transferring by the rotors of the gear pump is greatly increased. Unfortunately, when the longer teeth of the two rotors go to be near the inflection point of the “8”-shaped housing, because the profile of the longer tooth is not perfectly designed, the seal effect cannot be kept between the two longer teeth, resulting in a great amount of liquid backflow, thus the efficiency of the fluid transmission is caused at a low level, with nearly no function of compressing or expanding gas. In fact, although the two rotors keep engaging with each other, they are out of actual metallic contact with each other; additional torque transmitting gears have to be mounted outside so as to drive the shaft of the rotor, so the size of the rotor machine has to be increased.
U.S. Pat. No. 5,682,793 discloses an engaging rotor. When it is used for compressing gas, the gas in the tooth groove
3
of the rotor
1
cannot be compressed, only being moved from the inlet to the outlet. When the groove communicates with the compression chamber or the outlet, the gas is compressed at a constant volume, resulting in the power consumption increased and noise generated. When used for compressing gas, it becomes a rotor compressor with partial built-in compressing process. If every rotors are formed with a longer tooth and a longer tooth groove, when the longer teeth go to be near the inflection point of the “8”-shaped housing, the perfect seal effect cannot be realized, so some liquid will backflow and leak to the outside, thus the engaging rotor of this patent is inappropriate to be used in a compressor.
On the other hand, in the rotary compressors according to the prior art, the rotor compressors, the sliding-plate compressor, and the rotary vane compressor are all provided with the sliding-plates, the springs, the valves or the like which are easy to be damaged. The screw-rod compressor or the scroll compressor is simple in structure, but their curve surfaces are complex in shape, so it is difficult to be manufactured and checked. More particularly, in condition that those compressors are miniaturized, above-mentioned drawbacks are even worse. For the single tooth rotor compressor, the two rotors are out of actual metallic contact with each other, a clearance is kept between the corresponding engaging points of the two rotors. In such kind of compressor, a great of leakage between the two rotors can not be prevented, and it is difficult to make the compression ratio big enough. In fact, the single-stage compressor can only be used as an air blower. Because the rotors cannot transmit force to each other for their profiles, the angular position and the rotation of one rotor relative to another are controlled by a separate gear which can be synchronously rotated with said one rotor. The synchronous gear and its assembly make the compressor complex in structure and big in volume.
OBJECT OF THE INVENTION
An object of the present invention is to provide a gear as a component of fluid compressing or expanding machine so as to transport fluid more efficiently.
Another object of the present invention is to provide a gear whose inertia force when used as a rotor can be cancelled out completely, although the teeth of which have different sizes with respect to each other.
A further object of the present invention is to provide a gear pair for reducing the leakage between the two engaging gears as rotors.
An additional object of the present invention is to provide a compressor or expansion machine, which has a complete built-in compression process, so its compression ratio can be obviously enhanced, so that the single-stage compressor can also be used as the compressor for generating pressured gas and the compressor for refrigerator, without over compression and under compression.
Another object of the present invention is to provide a fluid machine which have a perfect sealing effect.
TECHNICAL SOLUTIONS
A gear pair according to the present invention are formed as at least two gear-shaped rotors that engage with each other, so that the driving force can be transmitted. The driving gear and the driven gear are provided with shorter teeth, transition teeth and at least one longer tooth on their pitch circles respectively. The cross-section of the longer tooth is of a hawk beak shape, and the profile of the longer tooth is smoothly connected one after another by a convex section of the longer tooth, a tip section of the longer tooth, a concave section of the longer tooth and a leading section of the longer tooth. A transition tooth is provided on each of the two sides of the longer tooth. Each transition tooth is provided in neighborhood relationship with the longer tooth on one side thereof and a shorter tooth on the opposite side thereof. That is, the teeth of gear according to this invention is distributed in the order of a shorter tooth, a transition tooth, a longer tooth, the other transition tooth, and another shorter teeth.
An external engaging gear pair according to the present invention comprises at least two gear-shaped rotors that engage with each other. The two rotors are provided with shorter teeth, transition teeth and at least one longer tooth on their pitch circles respectively. The shaft of the driving rotor and the shaft of the driven rotor are arranged to be parallel to each other. The center to center distance from the driving rotor to the driven rotor is equal to the radial sum of the pitch circles of the two rotors. The cross-section of the longer tooth is of a hawk beak shape, the profile of the longer tooth is composed of a convex section, a tip section, a concave section and a leading section of the longer tooth, which are smoothly connected one to another in series. The longer tooth is connected at its two sides to the shorter teeth via transition teeth.
At least one gear pair according to the present invention is formed as two gear-shaped rotors that engage with each other. One of the two rotors is an internal gear, and another is an external one, the two rotors are provided with shorter teeth, transition teeth and at least one longer tooth on their pitch circles respectively. The shaft of the driving rotor and the shaft of the driven rotor are arranged to be parallel to each other. The center to center distance from the driving rotor to the driven rotor is equal to the radial difference of the pitch circles of the two rotors. The cross-section of the longer tooth is of a hawk beak shape, the profile of the longer tooth is composed of a convex section of the longer tooth, a tip section of the longer tooth, a concave section of the longer tooth, and a leading section of the longer tooth. The four sections of the longer tooth are smoothly connected one to another in series, so as to form the profile of the longer tooth. The convex section of the longer tooth of the internal gear projects into the in
Denion Thomas
Seed IP Law Group PLLC
Trieu Theresa
LandOfFree
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