Involute spiral wrap device

Details Involute spiral wrap device Involute spiral wrap device

2001-03-26

2002-10-15

Freay, Charles G. (Department: 3746)

Pumps

Processes

C417S295000, C417S410500, C418S060000

Reexamination Certificate

active

06464467

ABSTRACT:

BACKGROUND OF INVENTION
This invention pertains generally to an involute spiral wrap (also known as a scroll) device with more than one pair of spiral wrap members, and more particularly to a pair of axially opposed scroll members operatively coupled through a common linkage to both an electric motor/generator and an auxiliary power device, all inside a hermetically sealed power module. The device has particular utility when used in one of two operating modes; first in an expansion mode, where the electric motor/generator functions solely as a generator, and is disposed on a rotational shaft coupled through the linkage to the scroll devices such that the conversion of shaft to electric power is enabled, and second, in a hybrid, or combination, mode, where simultaneously one scroll functions as an expander while the other functions as a compressor.
The use of meshed involute spiral wraps for both engine and compressor applications has been known since the early twentieth century. For example, U.S. Pat. No. 801,182 to Creux shows and describes the salient features of such a device, including the interspersing of two spiral bands that define radially intermittent, crescent-shaped chambers, and that the device can be used alternatively as an expander or compressor. The chambers are radially intermittent in that they translate radially between the center and the outer edge in response to the relative movement between the fixed and orbiting scrolls. Over the years, many improvements have been made to the design, increasing capacity, efficiency and system responsiveness. Additional features, such as modular componentry, lightweight materials for orbiting parts and hermetic sealing have all been employed in varying degrees. However, the demand for more throughput has resulted in both larger, more volume-intensive configurations, as well as having pushed the mechanical limits of conventional spiral wrap devices, with unbalanced thrust forces, higher operating temperatures and greater bearing loads placing considerable stress on the componentry. This in turn led to shorter part life and increased operational expense, thus hampering scroll device viability.
To meliorate this concern, larger bearing assemblies and shaft end housings to handle the thrust forces of the wrap members were added, as well as heat exchange devices to remove excess heat. Unfortunately, these solutions add to system volume, weight, complexity and cost. Another approach taken was to place back-to-back orbiting scrolls on a common shaft, each operably engaged with a stationary scroll. While this approach increased device capacity and reduced unbalanced axial loads, it also resulted in mechanical complexity and compromised discharge porting designs that presented new problems. Lighter weight materials were applied, most notably aluminum alloys and aluminum-based composites, to the orbiting scroll in an attempt to reduce inertial loading on the bearings, as well as to permit higher rotational operating conditions and lower differential radial pressure variations. However, additional manufacturing cost coupled with higher than acceptable wear rates adversely effected the viability of these lightweight material systems.
Other problems unique to scroll devices also became apparent. In expansion mode, the fixed volume-ratio scroll device will attempt to operate to a nearly fixed pressure ratio. This fixed pressure ratio constraint will force the working fluid within the expansion chamber to drop below the discharge cavity pressure, thus adversely impacting the efficiency of the scroll device.
Another traditional problem for refrigeration-cycle scroll devices pertains to their housing and containment. Hermetic sealing of housings offered twofold benefits: first, the sealing could protect the internal machinery when employed in harsh environs, where dirt, moisture and corrosives could adversely effect scroll performance and life; and second, with the increasing use of scroll devices in locations intolerant of the noise and mess associated with power-generating machinery, the clean, relatively maintenance-free operation of the hermetic scrolls meant their use could be placed in close proximity to such sensitive areas. While some scroll units utilize hermetic sealing, none fully integrate hermetic sealing with compact, fully autonomous operation that includes internal auxiliary power sources (for example, to drive lubrication and condensate pumps), as well as an unobtrusive cooling mechanism to meet the extra cooling demands of a hermetically sealed, high-output electrical generator, coupled inlet throttle control, integrated oil separation and fully automated operation.
Accordingly, the need exists in the art for a power generation system that can utilize the inexpensive, compact and reliable features of a scroll device in an expansion mode as well as a hybrid mode, both of which require high capacity, mechanical and speed/condition flexibility and fully autonomous operation.
SUMMARY OF INVENTION
According to an aspect of the present invention, an involute spiral wrap device is disclosed. It comprises a housing in which two pairs of meshed axially extending involute spiral wrap members are opposedly mounted on a common shaft, an antirotation device and eccentric linkage, or pin, to convert orbital movement to shaft rotational movement, an electric motor/generator in inductive electrical communication with the shaft, an auxiliary power source, a heat exchange system to exchange heat with the stator of the motor/generator, and at least one differential pressure valve to avoid or minimize select adverse pressure gradient conditions. The present invention features the use of a first pair of spiral wrap members oriented coaxially with, but in opposite direction to a second pair of spiral wrap members. By reducing the width of the scroll and placing the load on two spiral wrap member pairs, rotationally-induced scroll material stresses are reduced significantly. In addition, these reductions in rotationally-induced scroll loads leads to significant reductions in bearing size, bearing mechanical losses and to the size of related structural members. To minimize the radial forces of the spiral wrap pairs, the present invention features the use of one or more counterweights formed as part of the rotatable shaft. When the spiral wrap member pairs are operated in expansion mode, the electric motor/generator, which includes a shaft mounted rotor and stator, can be run solely as a generator which produces an electrical potential, thereby converting shaft horsepower generated by the expansion of a pressurized working fluid through the wrap members to alternating current electricity. The electrical energy can be passed through the walls of the housing through electrical conductors without the need for housing shaft seals that are typically required when using mechanical energy transmission, thereby preserving the hermetic sealing features. In the hybrid mode, one of the pairs of meshed involute spiral wrap members is responsive to energy input from the electric motor/generator, now functioning as a motor. As an external electrical potential is applied to the stator coils, it induces the rotor to turn, thereby rotating the shaft, which, through its coupling to the orbiting scroll, can compress the working fluid as it enters the chamber from its outer radial position and flows through the radially-inward moving crescent chambers to the center of the wrap members and out the scroll member discharge (thus acting as a compressor). Meanwhile, the other spiral wrap member pair is responsive to the input of high pressure working fluid through the throttle valve (thus acting as an expander), which is therefore capable of providing power to the common shaft, resulting in a concomitant reduction of external electric power required of the motor/generator to run the compressor. The electric motor/generator may, in the alternate, be divided up into separate modules, each in operable communication with the rotating shaft, with each dedicated to one or th

Affiliated with

Also associated with

Rating

Involute spiral wrap device does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Involute spiral wrap device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Involute spiral wrap device will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2950509