JPH01167492A - Volume type hydraulic machine having built-in variable compression ratio mechanism - Google Patents

Abstract

PURPOSE:To make it possible to change internal compression ratio in accordance with operating pressure with self function by providing through holes between the inside of a compression casing and the inside of a delivery casing and providing nonreturn valves on the delivery casing sides of the through holes. CONSTITUTION:Through holes 11a-14a by which are connected together a delivery pressure chamber 15a inner a delivery casing 15 and respective chambers 6, 7, 9, 10 divided with both volute members 1a and 2a, are drilled on a wall face of a fixed scroll 2. Nonreturn valves 11-14 are provided on the delivery casing 15 sides of these through holes 11a-14a. When operating pressure Pi becomes, for instance, Pi<Pb,Pc,Pd and Pi>Pa,Pe, nonreturn valves 12 and 13 open and nonreturn valves 11 and 14 close, thereby pressure Pf in the delivery pressure chamber 15a gets to Pf=Pi=Pb=Pc=Pd.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a positive displacement fluid machine such as a scroll fluid machine or a screw fluid machine in which internal compression is performed, and in particular to a built-in internal compression ratio unique to the fluid machine. This invention relates to fluid machines that operate at lower pressures than those produced by. The fluid machine is used to compress, monocularly, and suction air, gas, water vapor, etc.

[Conventional technology and problems]

Optimal compression P in conventional internal compression fluid machines
The V-line circuit is shown in FIG.

In the figure, Pl: inlet pressure, P2: discharge pressure (pressure caused by built-in internal compression ratio), l: inlet volume, V2: outlet volume (volume determined by built-in volume ratio), p: operating pressure (operating pressure), discharge pressure).

The built-in (optimal) internal compression ratio (P2/PI) is defined by the following theoretical formula.

(PZ/PI) = (Vl/V2)" where n: Polytropic index (V+/Vz): Built-in volume ratio Based on the above-mentioned built-in internal compression ratio (P2/PI), the third
Compression from state ■ to state ■ in the PV diagram in the figure is optimal compression.

However, if a pressure P lower than the optimum pressure P2 is required as the operating discharge pressure, an overcompression state will occur, and the work shown by the shaded area in the figure becomes extra work for the compressor, resulting in unnecessary power ( power) will be consumed.

Next, the above phenomenon will be explained regarding an actual fluid machine.

FIG. 4 is a sectional view of a main part of a conventional scroll device, showing one continuous spiral member 1 on the upper surface of the orbiting scroll 1.
A is installed eccentrically by a turning radius e on one continuous spiral member 2a on the upper inner surface of the fixed scroll 2 which also serves as an upper casing, and the orbiting scroll 1 rotates eccentrically as the main shaft (not shown) rotates. As a result, the contact point between the spiral members 1a and 2a moves from the periphery to the center, and as a result, the fluid is sucked through the suction port 4 and compressed in the middle.
The liquid is discharged from the discharge port 5 in the center.

In addition, in the figure, 3 is a thrust bearing and an anti-rotation mechanism, and 6 to
Reference numeral 10 denotes chambers A-E, P, -P divided by both spiral members 1a and 2a facing each other.

is the pressure in each of the chambers A to E, and P is the operating discharge pressure, that is, the operating pressure.

In the conventional scroll device described above, during operation, if the operating pressure (operating discharge pressure) Pi is smaller than the pressure PC generated by the built-in internal compression ratio, that is, if P2 = Pe > Pi in FIG. There is a problem in that unnecessary power corresponding to the shaded area in the figure is consumed.

FIG. 5 is a side sectional view of a conventional screw fluid machine, showing a pair of screw rotors on the driving side and the driven side (only the driving side rotor 21 is shown in the figure, and the driven side rotor is on the back side of the page). ) are supported by bearings 23 so as to mesh with each other within the casing 22, and at both axial ends of the casing 22, there is a volume associated with the meshing of the threaded portions of both rotors shown by two-dot chain lines. Suction port 24 in the enlarged part
However, a discharge port 25 is provided in each of the volume reduction portions. In addition, in the figure, Pi: operating pressure (operating discharge pressure),
Px: Suction pressure, PA-Pc: Internal pressure at each position.

In the conventional screw fluid machine described above, during operation, the fluid sucked in at the suction pressure P is inside the casing.
It is gradually compressed as PI-+PA-+P, →Pc,
It is compressed to the pressure of the PC and discharged. However, if the operating pressure P is smaller than this Pc, that is, if Pt = PC>P in Figure 3, unnecessary power corresponding to the shaded area in the figure will be consumed, and the power will be lost from the PC. There was a problem in that noise was generated due to sudden pressure changes to P.

The technical object of the present invention is to reduce unnecessary power consumption associated with overcompression and increase the partial load efficiency of the compressor when the operating pressure P is between P2 > Pi > Pt.

[Means for solving problems]

In order to solve the problems and technical problems of the prior art described above, the present invention provides a positive displacement fluid machine in which internal compression is performed, in which one or more compressors are installed between the inside of a casing that compresses fluid and the inside of a discharge casing. A through hole is provided, and a check valve is provided on the discharge casing side of the through hole.

[For production]

Since the present invention is configured as described above, during operation, if the operating pressure (operating discharge pressure) P of the fluid machine is smaller than the pressure P generated by the inherent built-in internal compression ratio,
Among the check valves in the through hole provided between the inside of the fluid compression casing and the inside of the discharge casing, the check valves provided in the section where the internal compression pressure is smaller than the operating pressure P remain closed, and on the other hand, The check valve provided in the section where the internal pressure is higher than the operating pressure P is opened.

Therefore, inside the fluid compression casing, the above operating pressure P
, without being compressed to a higher pressure, the operating pressure P,
Since the internal pressure PR is discharged to the outside, the work corresponding to the shaded area shown in the third tooth is saved, and the partial load efficiency is increased. Furthermore, since there are no sudden pressure fluctuations, noise is also reduced.

〔Example] Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of essential parts of a scroll fluid machine showing a first embodiment of the present invention, and in the figure, the same reference numerals as those shown in FIG. 4 indicate the same or similar parts. .

In the figure, a discharge casing 15 having a discharge pressure chamber 15a therein communicated with a discharge port 5a in the center of the fixed scroll 2 is integrally formed in the upper part of the fixed scroll 2 facing the orbiting scroll 1. Discharge casing 15
A discharge port 5 is provided in the center of the upper wall.

A discharge pressure chamber 15a inside the discharge casing 15, and each chamber 6 divided by both spiral members 1a and 2a. 7.
9. 10 (A, B, D, E) through holes 11a, 12a, 13a, 14a are bored in the wall surface of the fixed scroll 2, and each of these through holes 11a
Check valves 11 to 14 are installed on the discharge casing 15 side of ~14a.
are installed respectively. In addition, in the figure, 3 is a bearing and an anti-rotation mechanism, P1 to P are the pressures of chambers A to E, and P is the operating pressure.

is the pressure in the discharge pressure chamber 15a.

Since the structure is as described above, as the orbiting scroll 1 rotates eccentrically as the main shaft (not shown) rotates,
The contact point between the spiral members 1a and 2a moves from the periphery to the center, and as a result, fluid is sucked in from the suction port 4, and internal compression is performed while the fluid moves toward the discharge port 5a at the center of the fixed scroll. Pressure increases. When the operating pressure P is higher than the pressure 22 generated by the unique built-in internal compression ratio, all the check valves 11 to 14 in the through holes 11a to 14a are closed, so that the conventional things (
4), the discharge port 5 in the center of the fixed scroll 2
It is discharged into the discharge pressure chamber 15a from a and discharged to the outside from the discharge port 5.

However, the operating pressure P, for example, is Pi<Pb.

When PC, P, and P, > P, , P, the check valves 12 and 13 open, the check valves 11 and 14 close, and the pressure in the discharge pressure chamber 15a P, = Pi = P, = Pc=Pd.

As mentioned above, the discharge pressure chamber 1 is generated depending on the operating pressure P.
The built-in internal compression ratio changes from (P2/P, ) to (Pi /P, ) by opening and closing the check valves 11 to 14 due to the pressure difference between the pressure P in 5a and the pressure P3 to P in the scroll.
As a result, the internal compression changes from state ■ in the PV diagram in Figure 3 to state 2, and the work corresponding to the shaded area shown in the same figure can be saved, and the partial load efficiency is higher than that of the conventional structure (No. Figure 4).

FIG. 2 is a side sectional view of a screw fluid machine showing a second embodiment of the present invention, and in the figure, the same reference numerals as those shown in FIG. 5 indicate the same or similar parts.

In the figure, a casing 22 houses a pair of screw rotors (only the drive side rotor 21 is shown in the figure).
A discharge pressure chamber 28 communicating with the discharge port 25 is provided in a part of the discharge side of the
A discharge casing 28 having a diameter inside thereof is integrally formed, and a through hole 27a communicates between the discharge royal casing 28a and the position of internal compression due to engagement of the threaded portions of both rotors, which is desired to match the operating pressure P. , 26a is the casing 2
A check valve 27, 26 is provided on the discharge side of each of these through holes, and a check valve 27, 26 is provided on the discharge casing side of each of these through holes. In addition, in the figure, Pi: operating pressure, PI: suction pressure, PA-Pc:
This is the internal pressure at each position.

Since it is configured as above, for example, Pt=Pa
When Pt>PA, the check valve 26 is closed by the pressure of P, but the check valve 27 is open. In this case, the check valve is set to open when the pressure difference is 0, but of course it can be set to any pressure difference.

In this way, the inside of the casing is discharged at an internal pressure P that matches the operating pressure P without being compressed to the pressure P, so the work corresponding to the shaded area shown in Figure 3 can be saved and the partial load efficiency can be improved. It is higher than the conventional one (Fig. 5). Furthermore, since there are no sudden pressure fluctuations, noise can also be reduced.

In the above-described embodiment, a structure in which check valves are provided at two locations has been described, but by increasing the number of check valves, it is possible to adapt to even finer operating discharge pressures.

Further, although two types of displacement fluid machines that perform internal compression, a scroll fluid machine and a screw fluid machine, have been described, it is needless to say that the present invention is not limited to these.

〔Effect of the invention〕

As explained above, according to the present invention, in a positive displacement fluid machine that performs internal compression, one or more through holes are provided between the inside of a casing that compresses fluid and the inside of a discharge casing, and By providing a check valve on the discharge casing side, it is possible to change the internal compression ratio by its own function according to the operating pressure, so as to adapt it to the operating pressure.

Therefore, unnecessary power is not consumed during partial load, so
Efficiency can be improved and noise can be reduced.

[Brief explanation of the drawing]

1 and 2 are sectional views showing the first and second embodiments of the present invention, FIG. 3 is a PV diagram illustrating the operation, and FIGS. 4 and 5 are sectional views showing the conventional example. FIG. 1... Orbiting scroll, 2... Fixed scroll, 3
...Bearing and anti-rotation mechanism, 4...Suction port, 5, 5
a...Discharge port, 11-14...Check valve, lla-1
4a... Through hole, 15... Discharge casing, 21...
...Screw rotor, 22...Casing, 24.
...Suction port, 25...Discharge port, 26.27...Check valve, 26a. 27a... Through hole, 28... Discharge casing. Figure 5 9 et al.

Claims (3)

[Claims] 1. In a positive displacement fluid machine that performs internal compression, there is a space between the inside of the casing that compresses the fluid and the inside of the discharge casing.
One or more through holes are provided, and a check valve is installed on the discharge casing side of the through hole, so that the internal compression ratio can be adjusted according to the operating pressure by its own function. A positive displacement fluid machine with a built-in variable compression ratio mechanism. 2. The positive displacement fluid machine having a built-in variable compression ratio mechanism according to claim 1, wherein the positive displacement fluid machine is a scroll fluid machine, and the one or more through holes are provided in a fixed scroll. . 3. The assembly according to claim 1, wherein the positive displacement fluid machine is a screw fluid machine, and the one or more through holes are provided at the casing position of the internal compression that is desired to be matched with the operating pressure. A positive displacement fluid machine with a variable compression ratio mechanism.