KR20010042130A - Screw rotor compressor having a movable wall portion - Google Patents

Abstract

The present invention relates to a screw compressor having a rotor housing (1) and two helical screw rotors that interact. The housing 1 comprises a first end wall 2, a second end wall 3 and barrel walls 7, 11 which connect the two end walls to each other. The housing 1 has a form in which two cylinders cross each other internally, and the first end wall 2 includes an inlet opening 19. The barrel walls 7, 11 comprise an outlet opening 6 adjacent to the second end wall 3 and also comprise an additional opening 9, which further opening is the first from the outlet opening 6. It extends towards the end wall 2 and widens on both cylinder faces. The housing 1 also comprises a movable or displaceable part 11, which part interacts with the opening 9 and engages with the housing 1 in a first position to form cylinder faces which cross each other and And disengages the housing from the opening in the second position. The compressor also includes a steering device for positioning the movable part 11 in the first or second position. The steering device actuates the rotatable shaft 12, which is mounted to the compressor or fixed relatively firmly to the compressor and is connected with the movable part 11 via a connecting element 17.

Description

Screw rotor compressor with movable wall {SCREW ROTOR COMPRESSOR HAVING A MOVABLE WALL PORTION}

For this type of compressor, in many applications it is necessary to intermittently supply a compressed working fluid to the compressor. For this application, in order to avoid complicated and expensive solutions, for example, a coupling device or clutch mechanism is used between the compressor and the compressor drive means, or the actuation and deactivation of the drive means. To avoid the process, this type of compressor typically has means for keeping the compressor idle during periods when no compressed fluid is required. This is typically done by opening a free connection between the high pressure side and the low pressure side of the compressor for the return of the working fluid.

Such arrangements are disclosed, for example, in US Pat. Nos. 3,527,548, 3,759,636, 4,119,392, 4,799,865, and 4,993, 923.

The compressor disclosed in US-A1-3 527 548 has hollow axles or shafts, the interior of which communicates with the outlet through one opening and also with the inlet, which opens the valve. It can be closed by a pressure actuated valve against a spring force that functions to keep it open.

The compressor taught in US-A1-3 759 636 includes a valve that can be opened against oil pressure via an outfeed pressure with a pull spring at a high pressure end, the oil pressure being the outfeed. Act in the opposite direction of pressure; The valve opens the connection between the compressor outlet and the inlet.

The compressor disclosed in US-A1-4 119 392 is characterized in that the arm rotor is shorter than the distance between the end walls, and can be moved axially by a piston, which seals the high pressure end wall at full load or Spaced in the high pressure end wall, the high pressure side is fluidly connected with the inlet through the groove of the rotor to provide an idling function.

US-A1-4 799 865 discloses a compressor comprising an end wall movable axially at a high pressure end. The end wall can be kept closed by a spring and lifted by a piston or plunger to relieve the load on the compressor.

Finally, US-A1-4 993 923 discloses a pressure operated slide valve which is installed around the high pressure end of each rotor shaft, the pressure operated slide valve providing a fluid connection between the outlet and the inlet upon opening. .

A compressor comprising two screw rotors which interacts and which is used as an engine supercharger is disclosed in US patent specification US-A1-4 744 734. A disk-shaped throttle valve is provided at the end of the outlet passage of the compressor. The throttle disc is fixed to a shaft rotatable about its own long axis. The compressor also has a bypass passageway that connects with the compressor inlet. Two openings in the housing connect the rotor housing to the bypass passageway on one of the rotors, and a throttle valve pivotally mounted in the passageway to function to open and close the connection. An elastic arm fastened to the throttle valve shaft causes the pivoting throttle valve to open and close both openings in response to the rotation of the shaft. When both openings are closed in response to the rotation of the shaft, the outlet passage is opened by the valve disc. The reverse is also true.

European patent application publication EP-A2-0 484 885 discloses a screw rotor compressor having an inlet at one end of the compressor housing and a movable piston adjacent the outlet at the other axial end. The piston moves generally perpendicular to the axis of the screw rotors. Maximum compression occurs when the piston is located closest to the rotors. The size of the outlet opening increases as the piston moves away from this position, thus lower compression is obtained.

One of the drawbacks of this (the latter) compressor is that it cannot be made compact enough to meet many purposes. The movable piston, which will adjust the degree of compression obtained by the compressor, must have a significant length in the axial direction. It should also be possible to move the piston towards or against the contact position with the rotors without sticking or any jamming. The force exerted on the piston from the compressor room varies and is greatest near the outlet.

Another drawback is that when the piston is moved in the axial direction to change the compression ratio of the compressor, the piston may not rotate about its own axis. Since the piston is located on top of the two rotors, this rotation will cause the piston to contact the rotor, resulting in losses.

The present invention relates to a screw compressor having two helical screw rotors installed in and interacting with the rotor housing. The housing has first and second end walls connected to each other by a barrel wall. The housing has an internal structure where the two cylinders cross each other, the first end wall comprising an inlet opening, while the barrel wall comprises an outlet opening adjacent to the second end wall, and also from the outlet opening the first end wall. An additional opening extending toward and widening on both cylinder faces. The housing also includes a movable portion, the movable portion interacting with the additional opening, engaging with the housing in a first position to form a cylinder surface where the two cylinders cross each other, and in a second position. The engagement with the housing is released and spaced apart from the additional opening. The compressor includes a steering device for selecting the position of the movable portion in the first or second position.

1 schematically shows the compressor of the present invention from above, in which a movable part (moving part) with respect to the barrel housing is omitted.

FIG. 2 is an A-A cross sectional view through the cusps of the compressor shown in FIG. 1, with the omitted portion of FIG. 1 being shown in a first end position, and the second end position of the portion shown in broken lines.

3 shows a plan view of the movable part of the present barrel wall and also shows the means for moving the movable part between the two end positions.

4 is a cross-sectional view of the movable portion taken along the line B-B in FIG.

One object of the present invention is to eliminate the drawbacks of the solution specified in the European patent application for varying the compression ratio of the compressor.

Another object of the present invention is to provide a novel and improved method of shortening the circulation of working fluid with respect to idling of a compressor.

It is a further object of the present invention to provide a simple and reliable compressor with less demand for valve tolerance for adjustment of the compression ratio.

These objects have been achieved according to the invention by a compressor according to the preamble of claim 1, the preamble of claim 1 functioning to actuate a rotatable shaft in which the actuating device or steering device is mounted or relatively firmly fixed to the compressor, It comprises a variant that is rigidly connected with the moving part of the compressor barrel via the connecting element.

Since the valve plate, ie the movable portion of the barrel wall, is rotatable about an axis, it can be easily released and disengaged from engagement or engagement with the barrel wall and can be spaced apart from the rotors. This rotation opens the closed workrooms of the compressor, thereby immediately relieving the load on the compressor. The production of the compressed fluid immediately changes in one step or almost completely stops. When the movable portion extends from the outlet opening to the opposite end wall, or preferably ends a short distance from the wall, when the movable portion rises or moves away from contact with the fixed part of the barrel wall, all the rooms immediately fluid with one another. Will be connected. The losses due to backflow or reflux are reduced to a minimum. As a result, in order to provide idling conditions, the moving parts only require very little movement. To achieve this movement, only one simple steering device is needed, such as a motor or spring acting on the shaft in a suitable way. In one embodiment of the invention, the opening provided with the valve plate ends short of the first end wall, so that some compression ratio will be obtained even when the valve cover is not engaged with the barrel housing.

Another important advantage of the present invention is that the movable part can be fixed via the connecting element of the shaft. Since the connecting element has a wide and long contact area with the shaft, the movable part will be positioned exactly in the intended position in the compressor in combination with the barrel housing, and without additional guide elements, with only a small gap in between the vicinity of the rotors. Will be located at

When attaching the connecting element on the shaft and with the holes larger in diameter than the diameter of the screws or other fasteners (tightening mechanisms), there will be no adverse effect on the valve function even if the shaft is positioned at an inappropriate angle.

Wherever the movable part is arranged in the barrel wall, the position of the movable part is preferably perpendicular to the plane of intersection of the cylinders, since it provides a through connection with the grooves of the two rotors.

The compressor housing is made of metallic material, for example aluminum. However, the movable portion may be made of other material, for example a polymeric material.

Preferred embodiments of the invention are apparent in the dependent claims.

The invention will now be described in more detail with reference to the accompanying drawings.

The compressor shown in FIGS. 1 and 2 comprises a housing 1, which has a first end wall 2 comprising an inlet opening 19 on the inlet side (low pressure side) and an outlet. And a barrel wall 7, 11 connecting the second end wall 3 and the two end walls 2, 3 on the side (high pressure side) to each other. The barrel wall 7 provides a generally triangular outlet opening 6 therein, the base of which is located adjacent to the second end wall. The barrel wall consists of two parts, the first fixed main part 7 and the second movable part 11, the movable part being shown in FIGS. 2 and 3 and best shown in FIG. 3. The barrel wall 7 comprises an opening 9 intended to receive the movable part 11. The movable or displaceable movable part 11 is received into the opening 9 of the barrel wall 7 at the first end position, as shown by the solid line in FIG. 2. In FIG. 2, the position of the second end of the movable portion, that is, the position at which the movable portion is disengaged from the barrel wall 7, is indicated by broken lines.

Internally the compressor housing 1 has two cylindrical forms that intersect with each other and there are arranged interactive rotors with helical lobes therein. The center line of the rotors 4, 5 is shown in broken lines in FIG. 1, and is indicated by the rotor reference numerals.

In the illustrated embodiment, the opening 9 of the barrel wall 7 is circular and intersects with the government of the outlet opening 6 which is generally triangular. The opening 9 extends towards the first end wall 7, in the illustrated case all the way to the first end wall 2, ie in a plane perpendicular to the rotor axes, where the inlet pressure is still present.

3 shows the movable or displaceable part 11 from above. As shown, this configuration comprises a connecting element 17 connecting the shaft 12 and the movable part 11 mounted to the bearing 16. The bearing 16 is mounted on the stationary part 7 in an appropriate manner or on a support fixed to the compressor. One end of the shaft 12 extends beyond the bearing 16 and includes an arm 18. The arm 18 is actuated by the motor 25 or some other means (FIG. 1) via the transmission element 26 to rotate the shaft 12 to the limit. This rotational movement causes the movable part 11 to be moved between the end positions (Fig. 2) of the movable part or to a position between the end positions.

In section B-B of FIG. 4, the movable part 11 is perpendicular to the axes of the rotors 4, 5. On the movable part 11, the part of the lid housing, i.e. the cusp, has a reference numeral 20 and the two areas 21, 22 diverging from the cusp 20 are in the shape of a cylinder (cylindrical), It has the same radius of curvature as the cylinder. The movable part 11 has a flange 23 in contact with a corresponding recess 8 (FIGS. 1 and 2) in the barrel wall 7 around the opening 9. The circular side face 24 of the movable part 11 which is intended to be inserted into the opening 9 of the fixing part 7 is preferably tapered conically toward the inside of the housing. In this case, although there must be enough clearance for the movable part 11 to rotate and engage and disengage with the opening 9, it can alternatively be cylindrical. The conical structure allows the movable part 11 to be inserted into the opening 9 without a gap. That is, the conical surfaces are located in contact with each other. This means that the requirements are less stringent in terms of assembly precision. Thus, the circular part of the opening 9 will be conical or cylindrical in a corresponding manner.

In addition to the inlet passage or opening 19, the first end wall 2 comprises a connecting passage 14, which opens at one end to the side wall of the opening 9 and the other end to the compressor inlet. The passages 14 and 19 are both connected to the same source of working fluid. The passage 14 is connected to the movable portion 11 when the movable portion 11 is in one end position in engagement with (engaged with) the fixed portion 7.

In the illustrated case, the connecting element 17 has a rectangular block shape. The shaft 12 includes a flat recess for receiving one end of the block. The connecting element 17 comprises two holes parallel to each other into which a screw 13 or similar fastener (fastening part) holds the connecting element 17 in a position fixed with respect to the shaft 12. Similarly, two other holes parallel to each other extend perpendicularly to the first two holes mentioned above in which a screw or a fastener which secures the connecting element 17 to the movable part 11 is fitted. These holes have a larger diameter than the screws 13.

When the connecting element 17 is fastened to the shaft 12 and the movable part 11, the shaft 12 is mounted in the compressor housing and the movable part 11 is in a position to engage the opening 9. The connecting element is then fastened to the shaft 12 and the movable part 11 using the screws. Since the diameter of the hole is larger than the diameter of the screw 13, the shaft 12 can be mounted to the compressor at a “wrong angle” vertically and horizontally with respect to the plane of the contact area 8. It can also correct vertical errors.

An elastic cover may be provided in the recess around the opening 9 of the barrel wall. This cover or coating preferably functions as a sealant and consists of a polymeric material. This cover or coating is preferably provided on the flange 23 of the movable part 11, which flange 23 is located on the barrel wall 11 with respect to the recess around the opening 9.

The rotatable angle of the shaft 12 may be limited by the stop provided in the compressor or by the range in which the steering device 25 rotates the shaft 12.

When the compressor is running and compresses the working fluid, the movable portion 11 will be in the position indicated by the solid line in FIG. 2. Thus the passage 14 is closed for fluid passage. Working fluid, generally air, enters the working chamber of the compressor through the inlet opening 19. The rotors 4, 5, driven by means not shown and mounted in the work chamber, transfer the working fluid from the inlet opening 19 to the outlet opening 6 and simultaneously compress the working fluid. The working fluid is discharged from the compressor through the outlet opening 6.

Depending on the extent to which the opening 9 widens towards the first end wall, the supply of the compressed working fluid can be stopped entirely, or when the movable part 11 is disengaged from the barrel wall 7, the discharge fluid The output pressure of can be lowered. This is achieved by operating the arm 18, which is connected to the shaft 12 by the steering device 25, for example the second shown in dashed line in FIG. 2 from the first end position in combination with the barrel wall 7. The movable part 11 is rotated toward an end position. The working rooms of the compressors are interconnected and short circuit the inlet and outlet through the grooves of the rotor or reduce the compression area of the compressor respectively. At the same time the passage 14 is open. This lowers the pressure at the outlet 16.

Claims (10)

Two helical screw rotors 4 and 5 interacting, the rotor housing 1 and the steering mechanisms 18, 26 and 25, The rotor housing 1 comprises a first end wall 2, a second end wall 3 and barrel walls 7, 11 connecting the two end walls 2, 3, with two cylinders mutually connected. It has an intersecting internal shape, the first end wall 2 having an inlet opening 19, the barrel wall 7 having an outlet opening 6 adjacent to the second side wall 3 and an outlet opening ( A further opening 9 extending from 6) towards the first end wall 2 and widening above the two cylinder faces, the movable part 11 interacting with the opening 9 and in a first position In combination with (engagement) the housing (1) to form the mutually intersecting cylinder face, released from engagement with the housing (1) in a second position away from the opening (9), And the steering device 18, 26, 25 selectively positions the movable part 11 in a first or second position. In a screw rotor compressor, The steering device 18, 26, 25 drives a rotatable shaft 12, which shaft 12 is rigidly fixed to the compressor or mounted to the compressor, and through the connecting element 17 the movable part ( 11) screw rotor compressor, characterized in that connected to. The screw rotor compressor according to claim 1, wherein the rotatable shaft (12) extends at least generally perpendicular to the plane of intersection (cusps) of the cylinders. The screw rotor compressor according to claim 1 or 2, characterized in that the movable portion (11) has a circular cross section on an outer circumferential portion which is not bounded on the outlet opening (6). The screw rotor compressor according to claim 3, wherein the movable portion (11) has a truncated cone shape. The screw rotor compressor according to claim 3 or 4, characterized in that the movable portion (11) has a flange which contacts the barrel wall (7) when in the first position. 6. A screw rotor compressor according to claim 5, characterized in that a sealing coating or covering is provided in the region of the barrel wall (7) in contact with the movable portion (11) in the first position. Screw rotor compressor according to one or more of the preceding claims, characterized in that the opening (9) extends to the first end wall (2). The method according to claim 1, wherein the connection element 17 has a first flat surface in contact with the movable portion 11 and a second flat surface extending perpendicular to the first surface, the second flat surface being the shaft ( 12. A screw rotor compressor, characterized in that it is in contact with a flat recess extending parallel to the centerline of the shaft (12). The screw rotor compressor according to claim 8, characterized in that the movable part (11) is fixedly connected to the connecting element (17) after being located in a first position on the barrel face (7). The screw rotor compressor according to claim 8, characterized in that the movable part (11) is fixedly connected to the fixed shaft (12) after being located in a first position on the barrel face (7).