JP2656139B2 - Inlet with multiple slots for screw expanders / compressors - Google Patents

Description

The present invention relates to a multi-slot suction port for a screw expander / compressor.

BACKGROUND OF THE INVENTION Problems to be Solved by the Invention Screw rotor positive displacement machines for elastic working fluids are well known as co-pressors and expanders.
In such a machine, two intersecting lumens having parallel axes and defining a boundary wall surrounding the working space, and high and low pressure end walls arranged perpendicular to the axes of these lumens And a casing having a high pressure port and a low pressure port. Each lumen has one rotor of a pair of so-called male and female intermeshing rotors having spiral lands and intervening grooves. Each rotor has a winding angle of less than 360 °. The male rotor is formed with convex lands and usually has a major portion of each land outside the pitch circle. The female rotor is formed with concave lands, typically having a major portion of each land inside the pitch.

An advantage of this type of compression or expansion machine is that when performing dry operation (ie, operation with a gaseous medium without any liquid lubricant), the two rotors are kept apart from each other by the synchronous gear, and thus lubrication. The friction and seizure of the rotor surface which is not performed is avoided. Synchronous gears usually move in a closed case where they can be lubricated.

Instead, lubricant is injected into the gas compression or expansion space, in which case the rotors can be moved against each other. In this case, a precise and expensive synchronous gear is not required. However, the oil must be separated from the gas after compression. When operated as a gas inflator, it is usually inconvenient to use a lubricant in a gaseous medium,
Therefore, a synchronous gear must be used.

A typical example of a machine having a screw is shown in FIGS.
The operating principle and the method of operating the machine as an expander and as a compressor are illustrated in the figures, FIGS. 3 and 4, and will be explained below with reference to the drawings.

FIG. 1 illustrates the rotors 4, 5 as they are housed inside the casing 1, as viewed from the suction end of the machine. 2 is the suction port of the machine and 3 is the suction side of the machine. Reference numerals 8 and 9 denote synchronous gears typically used in a compressor having no lubricant in its working chamber. FIG. 2 shows the casing 1 for clarity of illustration.
The rotors 4 and 5 and the synchronous gears 8 and 9 are shown in the drawing. Arrows 6 and 7 indicate the rotation directions of the rotors 4 and 5, respectively.

In FIG. 2, the rotors 4, 5 are shown in the same arrangement as in FIG. 1 (i.e., the suction port end and the suction port side face the viewer of the drawing).

FIG. 3 shows the machine viewed from the outlet side of the machine, again with the suction port end facing the viewer of the drawing. FIG. 3 is therefore a view from the lower side of FIG.

In FIG. 3, reference numeral 10 denotes a discharge port. FIG. 4 has the casing removed and with the same arrangement as FIG. 3 (ie,
The discharge port side and the suction port end face the viewer of the drawing)
The rotors 4 and 5 are illustrated.

Considering FIG. 1 and FIG. 2, the rotors 4,5 are indicated by arrows 6,7.
, The air gap defined by the surfaces of the grooves 15, 16 of the rotors 4, 5 and the surface of the casing 1 increases. This action draws gas into the void. When the leading edges 11, 12 of the rotor profile pass through the edges 13, 14 of the inlet 2, said gap is effectively closed. This closing point is usually chosen to occur at the point where the air gap has been expanded to their maximum or near-maximum volume by rotation of the rotors 4,5 (for example, in FIG. 2, the grooves 15,5 of the rotors 4,5). The gap defined by 16 is shown as being in this state).

If the drawing is made on the outlet side of the rotors 4, 5 as in FIG. 4, the grooves 15, 16 are found to rotate towards each other, and if the rotors 4, 5 If is further rotated, the cooperating meshing of the rotor reduces the volume of the air gap defined by the surfaces of the grooves 15, 16 of the rotor and the inner surface of the bore of the casing 1 and thus confine it there. Causes compression of the gas being processed.
In FIG. 4, it can be seen that the gap defined by the surfaces of the grooves 17, 18 and the inner surface of the casing is greatly reduced as compared to the gap defined by the grooves 15, 16.

The location of the edges of the outlet 10 is chosen so that the voids described above are not exposed to the outlet 10 until their volume has been reduced to the specific required degree. Therefore,
The degree of compression occurring inside the machine can be predetermined.

Referring again to FIGS. 1 and 2, if the suction port 2 of the machine reaches its maximum volume, the gap defined by the grooves 15, 16 of the rotors 4, 5 and the inner surface of the casing 1 If previously closed, expansion of the gas trapped in the air gap occurs as the rotors 4,5 continue to rotate and thus increase the volume of the air gap. Thus, with judicious selection of the inlet close position and the outlet open position, the machine may have the ability to act as both an expansion means or expander and a compression means or compressor.

One application where this is potentially beneficial is in institutional supercharging. In particular, it is useful in applications for pyrotechnic engines where the amount of fuel and air drawn into the engine for each suction stroke must be varied and adjusted according to the power required for the engine. This partial load regulation is usually achieved by a slot in the air flow into the engine. However, since throttling is an irreversible process, there is an associated power loss in the engine piston during the suction stroke.

A more efficient method for part-load engine operation is probably to reduce the charge density using the expansion capacity of the screw turbocharger instead of throttling adjustment. By doing so, some of the effects of the engine piston associated with the suction stroke can be restored.

However, it has heretofore been difficult to completely close the inlet of a screw-type expander / compressor in an effective and controlled manner.

According to the present invention, a casing having two intersecting lumens and a high-pressure end wall and a low-pressure end wall disposed perpendicular to the axis of these lumens, Male and female 1 meshing and rotating inside
An inlet provided with a plurality of slots of a screw type expander / compressor having a pair of rotors, each having a number of slots whose opening area on the rotor chamber side is smaller than one low pressure side end face of a land of the rotor. These slots are provided so as to open to the low-pressure side end wall of the rotor chamber of the expander / compressor, and a control surface having means provided for closing and closing the slots is provided on the control surface.
As the slots are sequentially closed in an expansion cycle, they progressively earlier close up the expanding space defined by the intermeshing rotating rotor and casing of the expander / compressor. Is provided.

Next, an embodiment of the present invention will be described with reference to the accompanying drawings. In FIG. 5, the rotor 3
The expander / compressor that confines 1,32
It is shown in perspective as viewed from the inlet end and the inlet side of the machine. 21 is the suction end of the machine and 22 is the suction side of the machine. 23 and 24 are synchronous gears.

Numeral 25 is a slot that allows gas to enter the machine at the inlet rotor end of the male rotor 31. 26 is a slot that allows gas to enter the machine at the suction rotor end of the female rotor 32. Slot 25 may be the same length as slot 26, or may be longer or shorter in length. These slots may be of any shape, for example, as shown in FIG. 10, and may be provided with walls that further subdivide to form a honeycomb structure. In FIG. 10, reference numeral 37 denotes a honeycomb structure having a plurality of honeycomb-shaped holes defining a gas transfer slot. Two
7,28 are control surfaces and 29,30 are control means.
These control means are shown here as sectors.
The sectors are rotated so that they obscure the slots 25, 26 more or less by their location adjacent to the control surfaces 27, 28.

The sectors can be operated independently of each other or linked to operate in a predetermined manner.

FIG. 6 has the same arrangement as in FIG. 5 with the casing removed for clarity of illustration, i.e. with the inlet end and the inlet side facing the viewer of the drawing, and the rotors 31, 32 Illustrated. Arrows 41 and 42 indicate the direction of rotation of the rotor.

FIG. 7 is an elevational view of the end of the machine inlet observed along the arrow indicating the slot end (FIG. 5), showing the appearance of the slot end on the control surface. The sectors of the control means are shown in their open position.

FIG. 8 shows the slot and the fan of the control means AA
FIG. 8 is a partial cross-sectional view taken along the line (FIG. 7).

FIG. 9 is an end elevational view similar to FIG. 7, except that the fan of the control means covers some of the slots 25, 26 communicating between the suction end of the working chamber and the control surface. FIG.

When the sector plates of the control means 29, 30 are in a position exposing all slots, the machine acts as a pure compressor.

To make the machine work as an expander, both control means
29, 30 are rotated to cover and close off some of the slots (illustrated in FIG. 9). Land edges 33, 34 of rotors 31, 32
While passing through the last remaining open slot, the space trapped in the casing by the rotor lands and the casing wall is closed off before reaching the maximum.
As the rotors 31, 32 continue to rotate, the space increases, thus causing the expansion of gas trapped therein. This expansion appears as a force contribution at the rotor shaft.

If greater expansion is required, control means
29,30 The fan is rotated to cover and close more slots.

Since the flow of air to the engine must be controlled in a gradual manner, the sector of the control means must be able to be moved in a gradual manner.

As each slot is closed, the expansion effect is increased in stages, and as the sector progressively closes the next slot, the flow rate is gradually reduced until it is finally closed in that slot. However, by providing a large number of slots, the amount of aperture created at any one time is very small, and thus the aperture loss is reduced to a very small amount.

The slot between the control surface and the rotor chamber is sealed off by any one slot with the land end face of the rotor so that the expanding gas space confined in the different meshing of the rotor is not interconnected. It is important to end at the end face of the rotor chamber with a shape and dimensions that can be achieved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a typical example of a machine having a screw, that is, a screw type expander / compressor.
FIG. 3 is a perspective view of the machine of FIG. 1 with the rotor and synchronous gear removed with the casing removed for clarity of illustration;
1 is a perspective view showing the lower surface of the machine of FIG. 1 and viewed from the side of the discharge port, and FIG. 4 is a casing of the machine of FIG. FIG. 5 is a perspective view showing a groove portion, FIG. 5 is a perspective view of one embodiment of a machine or a screw type expander / compressor according to the present invention, and FIG. With the same arrangement as above, that is, with the suction port end and the suction port side facing the viewer of the drawing, the rotor 3
FIG. 7 is an elevational view of the end of the machine suction port observed according to the arrow (FIG. 5) showing the slot end, showing the appearance of the slot end on the control surface;
FIG. 8 is a partial cross-sectional view taken along the line AA (FIG. 7) showing the slots and the fan of the control means, and FIG. 9 is an end elevation view similar to FIG. Is an elevational view shown at one of those locations where the sector plate of the control means covers some of the slots communicating between the inlet end of the working chamber and the control surface; FIG. 10 shows the gas transfer slots. FIG. 3 is an elevational view showing a honeycomb structure having a plurality of honeycomb-shaped holes to be defined. In the drawing, 20 ... casing, 21 ... end of suction port, 23, 24
…… Synchronous gear, 25,26 …… Slot, 27,28 …… Control surface,
29, 30 ... control means, 31, 32 ... rotor, 33, 34 ... rim, 3
7 ... Honeycomb structure.

Claims (7)

(57) [Claims] 1. A casing having two intersecting lumens and a high pressure end wall and a low pressure end wall disposed perpendicular to the axis of the lumens, and a male and female rotating in mesh with said lumens. A suction port having a plurality of slots of a screw type expander / compressor having a pair of rotors, each of which has a smaller opening area on the rotor chamber side than one low pressure side end face of a land of the rotor. And a control surface having means provided for closing off the slot, the slots being sequentially provided in the expansion cycle, the slots being provided on the low pressure side end wall of the rotor chamber of the expander / compressor. Defined by the intermeshing rotating rotor and casing of the expander / compressor at progressively earlier stages when closed. Suction port provided with a plurality of slots of screw expander / Kopuressa, characterized in that bind to close off the space to expand that. 2. A screw-type extract according to claim 1, wherein said means for closing said slot on said control surface is a single rotating sector plate. Suction port with multiple slots for panda / compressor. 3. A suction port with a plurality of slots according to claim 1, wherein the means for closing the slot on the control surface is two rotating sector plates, one of which is a male rotor. Suction with a plurality of slots of a screw expander / compressor, characterized in that it is a sector plate closing the slot reaching the end and the other one is a sector plate closing the slot reaching the end of the female rotor. mouth. 4. A plurality of screw expanders / compressors according to claim 3, wherein two rotating fan plates are connected to each other at the plurality of slotted suction ports. Inlet with slot. 5. An inlet provided with a plurality of slots according to claims 1, 3 and 4, wherein:
A slot disposed about the axis of the male rotor that connects the suction port end of the male rotor chamber to the control surface is disposed about the axis of the female rotor that connects the suction port end of the female rotor chamber to the control surface. A plurality of slots for a screw-type expander / compressor, characterized in that they are of a different length than the slot. 6. An inlet having a plurality of slots as claimed in any one of claims 1 to 4, wherein the slots are adapted to optimize the structural rigidity of the matrix. An inlet with a plurality of slots for a screw expander / compressor characterized by being structured with a tissue. 7. The movement of the fan-shaped plate in the suction port having a plurality of slots according to any one of claims 2 to 5, wherein the movement of the sector plate is performed manually or by servo mechanism means. An inlet with a plurality of slots for a screw expander / compressor characterized by the following.