Helical-blade fluid machine

Rotary expansible chamber devices – Helical working member

Reexamination Certificate

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Details

C418S151000, C418S152000, C418S055600

Reexamination Certificate

active

06338617

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a helical-blade fluid machine applicable to compressors, expansion machines, pumps, etc.
2. Description of the Prior Art
A helical-blade fluid machine has, in a closed casing, a cylinder and a roller piston eccentrically arranged in the cylinder. The peripheral surface of the roller piston has a helical groove in which a helical blade is inserted to define compression chambers in the cylinder. Relative motion between the cylinder and the roller piston draws coolant gas from an intake end of the cylinder into the compression chambers and successively conveys and compresses the gas toward a discharge end of the cylinder. The compressed gas fills the casing and is discharged outside.
Generally, the helical-blade fluid machine directly draws gas into a compression mechanism, compresses the gas therein, once discharges the compressed gas into the casing, and sends the gas outside through a discharge pipe attached to the casing. As a result, the casing must contain a high-pressure atmosphere. The compression mechanism intrinsically has a long axis that needs long bearings.
The compression mechanism is conventionally designed to partly submerge in a lubricant pool in the casing. This dissolves much coolant in the lubricant under the high-pressure atmosphere, thereby increasing the temperature of the lubricant and decreasing the viscosity thereof to improperly lubricate the long bearings of the compression mechanism.
The coolant may be an HFC-based high-pressure coolant, which has a very high saturation pressure. For example, the saturation pressure of R
410
A is about 1.5 times higher than that of conventional R
22
. The casing of the fluid machine must withstand such high pressure. Namely, the casing must have a thick wall, which increases the weight as well as cost of the fluid machine.
When the roller of the compression mechanism in the lubricant pool is driven, it stirs the lubricant, to destabilize the supply of the lubricant, thereby destabilizing the torque and total operation of the compression mechanism.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a helical-blade fluid machine capable of isolating lubricant from high pressure and high temperature and properly lubricating sliding parts of a compression mechanism.
Another object of the present invention is to provide a helical-blade fluid machine having a casing that is thin and light.
Still another object of the present invention is to provide a helical-blade fluid machine having a roller that does not stir lubricant, thereby securing the stable operation of a compression mechanism.
Still another object of the present invention is to provide a helical-blade fluid machine capable of separating coolant gas from coolant liquid, preventing a compression mechanism from drawing the coolant liquid, to prevent an overload operation, avoiding the coolant gas from being heated, and securing efficient compressing conditions.
In order to accomplish the objects, an aspect of the present invention provides a helical-blade fluid machine having a closed casing, a cylinder arranged in the casing, a roller eccentrically arranged in the cylinder, a helical blade having unequal pitches to define compression chambers between the cylinder and the roller so that the volumes of the compression chambers gradually decrease in an axial direction, a drive mechanism for swaying the roller with respect to the cylinder, to axially move each of the compression chambers so that the volume of the compression chamber gradually decreases to compress gas contained therein, an intake pipe connected to the casing to guide gas into the casing and fill the casing with a low-pressure atmosphere, and a discharge pipe communicating with a discharge-end one of the compression chambers, to guide compressed gas from the discharge-end compression chamber to the outside of the casing.
The cylinder, roller, and helical blade form a compression mechanism, which is driven by the drive mechanism. The drive mechanism is electrical and is disposed under the compression mechanism.
The compression mechanism may draw gas from a lower part thereof and compresses the gas in the compression chambers while conveying the gas upwardly.
The compression mechanism may draw gas from the peripheral face of the cylinder into the compression chambers.
The compression mechanism may draw gas from a lower part of the roller into the compression chambers.
This fluid machine isolates gas drawn into the machine from lubricant and efficiently feed the gas into the compression chambers. The lubricant is under a low-pressure atmosphere containing the gas drawn into the casing, and therefore, is free from high pressure or high temperature. As a result, the lubricant maintains proper viscosity to smoothly lubricate bearings that are axially long. The low-pressure atmosphere in the casing enables the casing to have a thin wall to reduce the weight thereof. The roller never agitates the lubricant, thereby stabilizing the operation of the compression mechanism.
The present invention prevents lubricant that has lubricated the bearings from dropping onto a rotor of the drive mechanism and being scattered thereby. To realize this, a lubricant passage is formed through a first support frame that supports a rotating shaft of the compression mechanism. The lubricant that has lubricated the bearings of the compression mechanism passes through the lubricant passage and drops on or around a stator of the drive mechanism.
The fluid machine may have a first volume chamber in the cylinder and a second volume chamber above the cylinder. The first and second volume chambers communicate with each other, isolate discharged gas from lubricant, muffle noise, and reduce passage resistance.
The cross-sectional area of the first volume chamber may be tapered to widen toward the second volume chamber.
A check valve may be arranged in a port between the first and second volume chambers, to prevent a reverse flow from the second volume chamber toward the first volume chamber.
To secure a sealed state for a long time between a high-pressure area and a low-pressure area, an annular seal may be arranged around the second volume chamber or around an end face of the roller. The center of the annular seal is aligned with the center of the shaft.
It is preferable in this case that the bottom of the second volume chamber serves as a bearing to support the top end of the shaft.
In the fluid machine, a second support frame has a bearing for supporting the top of the shaft. To surely lubricate a top part of the compression mechanism, a lubricant passage axially formed through the shaft and a bearing space formed between the top end of the shaft and the bearing of the second support frame are used to lubricate the bearing of the second support frame.
The lubricant passage axially formed through the shaft is shifted from the axis of the shaft so that lubricant may smoothly rise in the passage due to centrifugal force.
To properly lubricate sliding parts of the compression mechanism, the lubricant passage formed through the shaft is connected to a lower part of the bearing of the first support frame and an upper part of the bearing of the roller.
To prevent the vibratory rotation of the drive mechanism, the shaft is shared by the drive mechanism and compression mechanism, and an end of the shaft passed through the drive mechanism is supported by a third support frame.
To balance the compression mechanism with centrifugal force, first and second balancers are attached to the shaft in the roller of the compression mechanism.
To prevent gas from being heated or from catching lubricant, the compression mechanism may be constituted to draw gas from an upper part thereof and compress the gas while conveying it downwardly.
To surely seal a high-pressure part from a low-pressure part in a compressed gas discharging area, a seal may be arranged on the discharge side of the roller of the compression mechanism.
To provide a muffling effect,

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