JPS6179886A - Screw compressor for gaseous medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a screw compressor for gaseous media, and more particularly, it relates to a screw compressor for gaseous media, and more particularly, to a screw compressor for a gaseous medium, and more particularly, to an inlet for uncompressed media in the housing, an outlet window for compressed media in the front wall or peripheral wall of the housing, and a pressure chamber located behind the outlet window. The present invention relates to a screw compressor for gaseous media, comprising a pressure pipe connected to a pressure chamber and conveying the compressed medium.

Screw compressors are provided with a discharge window for the medium compressed between the intermeshing rotors. The pressure ratio inside the compression depends on the cross-sectional area of the discharge window. Determined by

If this screw compressor has to be used for other pressure ratios, the pressure windows must be designed with other dimensions.

If the internal pressure ratio is not equal to the pressure ratio in the system into which the compressed medium is fed from the screw compressor, there will be over- or under-compression, both of which can lead to undesirable damage. Connect.

BACKGROUND OF THE INVENTION In the case of a known screw compressor of the above-mentioned type (GDR 11 14 6 319), the shape of the discharge window is varied to enlarge or reduce the discharge cross section in order to change the pressure ratio. For this purpose, it can be vibrated or moved,
Segments are used whose shape matches the contours of the rotor and the discharge window. If the ejection window is formed so that its shape changes in this way, manufacturing is complicated and failures are likely to occur during driving.

[Problem that the invention seeks to solve]

The object of the invention is to improve a screw compressor belonging to the technical field mentioned above, in order to adapt the internal pressure to the external pressure prevailing in the device connected to the screw compressor.

Means for Solving Problem c] According to the present invention, the problem is that the cross-sectional shape of the ejection window does not change, and that in addition to the ejection window and separately from the ejection window, a The solution is that at least one provided hole leads from the interior of the housing to the pressure chamber and that a spring-loaded overflow valve is provided in this hole.

〔Example〕

The following description of the preferred embodiments, taken in conjunction with the accompanying drawings, provides a detailed explanation of the invention.

The housing 1 of the screw compressor for gaseous media shown in FIG. 1 is provided in a known manner with an intake 2 for uncompressed media and a pressure chamber 3 for compressed media. This pressure chamber 3 is connected via a pressure pipe 4 to a device (not shown), for example a cooling device or an air conditioner, into which the medium compressed in the screw compressor is supplied. The pressure chamber 3 is formed in a housing wall 5 that closes off the front side of the housing 1 . The interior space 6 of the compressor is likewise connected in a known manner to the pressure chamber 3 via a discharge window 7 (see FIG. 2) having a defined external contour.

In the recesses 8, 9 of the housing 1 or the wall 5 are accommodated bearings for two threadedly meshed rotors, whose mutually parallel axes are designated by the reference numeral 11 in FIG.
It is indicated by 12.

The arrangement of both axes is indicated by a dashed line 13 in FIG.

As is clear from FIG. 2, the screw compressor of this embodiment is provided with a main rotor 14 having a large diameter and a sub rotor 15 having a small diameter. The mutually meshing thread-like gears of the two rotors 14, 15 are shown in dotted lines in FIG. 2 and are numbered 16-17. One rotor,
Typically, the main rotor 14 is driven by a motor (not shown), and the auxiliary rotor follows.

The evacuation window 7 (FIG. 2) has a cross-sectional shape that does not change once determined by its outer contour, and on the sides of the wall 5, at a distance consisting of the evacuation window 7, holes 18, 19 are provided.
, 21 are provided, which, like the discharge window 7, communicate from the housing interior space 6 to the pressure chamber 3. These holes 18, 19, 21 are provided in addition to and separately from the evacuation window 7, and do not communicate directly with the evacuation window.

An overflow valve 22 is arranged in each hole 18, 19, 21, and the valve attached to hole 18 is the third one.
As shown in the figure. Each overflow valve 22 is provided with a valve body 24 which is biased by a pressure spring 23 and is able to seal the respective bore 18 , 19 , 21 against the passage of medium. In the illustrated embodiment, the main rotor 14 corresponds to two overflow holes [8 and 19], and the auxiliary rotor 15 corresponds to an overflow hole 21. In principle, it is sufficient to have only one overflow hole or for each rotor to be associated with just one overflow hole, in which case the holes have different diameters. It is also possible. Depending on whether the overflow valve is open or closed, the total discharge cross-section of the screw compressor is respectively greater than or equal to the discharge cross-section of the discharge window 7. The dimensioned evacuation window 7 is selected according to the maximum possible pressure ratio of the device. The overflow valve 22 is then arranged to reach a determined lower external pressure ratio that essentially does not lead to overcompression within the screw compressor.

In the closed state (FIG. 3), the respective holes 18, 19, 21 of the overflow valve 22 are closed, and the sections 24 are
Each hole is almost completely closed, and the valve body 24 is
The surface 25 facing the housing interior space 6 (located on the left in FIG. 3) is colinear with the inside of the housing wall 5 and has the same contour. In this way, the internal space 6
On the side of the rotor inside, there are no harmful spaces for the medium to be compressed with backflow paths that could lead to damage.

If the internal pressure in the housing 1 becomes greater in the area of the discharge window 7 than the pressure of the device outside or in the pressure chamber 3, one or more overflow valves 22 open, so that the compressed medium The entire discharge cross-section of is increased and automatically adjusted to the correct pressure ratio.

In the illustrated embodiment, the pressure chamber 3 is axially offset with respect to the interior space 6 of the compressor. It is also possible for the pressure chamber 3 to be radially offset with respect to the interior space 6 , that is to say for example to be arranged in the peripheral wall 26 of the housing 1 facing the inlet 2 . Of course, in this case also the discharge window 7 is located in the above-mentioned area of the jacket, and the hole for the overflow valve is likewise arranged in the jacket 26, offset laterally with respect to the discharge window. The pressure pipes 4 which discharge the pressure chamber 3 radially in FIG. 1 can also be connected to the pressure chamber 3 such that the discharge of the compressed medium takes place axially with respect to the screw compressor.

The main advantages of the proposed screw compressor are as follows.

The economic range of use of this screw compressor extends over a relatively large pressure ratio range.

A hole corresponding to the discharge window and having an overflow valve is particularly preferred if the rotational speed of the screw compressor is regulated in an installation with a heat exchanger. This is because, due to heat conduction in the heat exchanger, a large pressure ratio will predominate when the rotational speed is low, and thus a small pressure ratio will predominate as the rotational speed decreases. Screw □
The oil injection into the compressor is also particularly reliable due to the provision of the overflow valve, even under variable operating conditions. This is because the pressure ratio inside the compressor is highly matched to the pressure ratio outside the device, so that at the injection point no pressure can rise above the pressure prevailing inside the device. It should be noted that an essential advantage is that the bore overflow valve according to the invention is particularly easy to manufacture;
This means that it actually works without any breakdowns and without any maintenance.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view of the housing of a screw compressor;
FIG. 2 is a front view of the screw compressor in the direction of the arrow in FIG. 1, and FIG. 3 is a sectional view showing a spring-biased overflow valve. 1...Housing, 2...Intake port, 3.
...Pressure chamber, 4...Pressure pipe, 5.
・・Housing wall, 6・Internal space, 7・・
・Ejection window, 8, 9...notch, 11,
12... Rotor axis, 13... Single-dot chain line, 14
, 15... Rotor, 16, 17... Gear cutter, 18, 19, 21... Hole, 22.
...Overflow valve, 23...Press spring, 24.
... Valve body, 25... surface, 26...
Peripheral wall. Margin below

Claims (1)

[Claims] 1. Rotors that are driven in a threaded manner and whose axes are arranged in parallel, a housing that surrounds these rotors, and an inlet for uncompressed media provided in the housing. a discharge window for the compressed medium provided in the front or peripheral wall of the housing; a pressure chamber located behind the discharge window; and a pressure pipe connected to the pressure chamber for conveying the compressed medium. In a screw compressor for gaseous media, the cross-sectional shape of the discharge window (7) does not change, and in addition to and separate from the discharge window (7) there is provided a screw compressor for gaseous media in front of the housing (1). Holes (18, 19, 21) provided in the wall or peripheral wall connect to the internal space (6) of the housing.
) into the pressure chamber (3) and that this hole (
18, 19, 21) with a spring-loaded overflow valve (2
2) A screw compressor for a gaseous medium, characterized in that: 2. The housing (1) in which the discharge window (7) and the holes (18, 19, 21) are located approximately perpendicular to the rotor axis (13).
) in the front wall (5) of each rotor (14, 15).
at least one hole (18) having an overflow valve (22);
21. A screw compressor according to claim 1, characterized in that: 3. Overflow valve (22) closing holes (18, 19, 21)
) of the valve body (24) almost completely blocks the hole in the closed state, and the face (25) of the valve body facing the housing interior space (6) is flush with the inside of the housing wall (5, 26). The screw compressor according to claim 1 or 2, characterized in that the screw compressor is on a line.