JPH0119075B2 - - Google Patents

Abstract

A capacity control valve for a compressor comprising a suction chamber (1) and a delivery chamber (2) and therebetween a connection (15) controlled by the control valve. The delivery chamber (2) is coupled to a pressure pipe. The control valve consists of a slide (7) provided axially slidable in a closed valve chamber (3, 4, 5 and 6). The wall of the valve chamber is provided with a number of ports (9) in a plane perpendicular to the sliding direction of the slide 7. The ports (3) connect the internal space (3,4) of the valve chamber to the delivery chamber (2). At both sides of the ports (9), the spaces (4 and 3) of the valve chamber have a connector for connections to the suction chamber (1) and pressure pipe respectively. In both of the end positions of the slide (7), a sealing part (12) thereof engaging the valve chamber wall releases the ports (9) at least partly.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention provides a suction chamber and a delivery chamber connected to a pressure pipe, with a connection between the delivery chamber and the connection to the pressure pipe, which is sealed by a valve. The present invention relates to a capacity control valve for a compressor. Such controls are generally known and used in piston compressors sold by the applicant.

Piston compressors are commonly used in refrigeration facilities to compress refrigerants, especially gases or vapors.
If the compressor or part of the compressor is under compression by one or a set of pistons, gas is conveyed from the suction chamber to the delivery chamber and pumped out from there via the pressure pipe. However, if the compressor or part of the compressor is not in operation, the valve is actuated to open communication between the delivery chamber and the suction chamber.
In this so-called recirculation condition, the refrigerant is recirculated by the piston from the suction chamber to the delivery chamber and from there back to the suction chamber. However, in the recirculation conditions described above, the delivery chamber and the pressure pipe should be separated to prevent backflow of refrigerant from the pressure pipe. This separation takes place in a known manner by a check valve connected in the refrigerant passage from the delivery chamber to the pressure pipe.

The known control therefore has the disadvantage of having to install a non-return valve, which means that in the compressed state there is a restriction passage, which results in an undesirable pressure drop.

It is an object of the invention to provide a displacement control valve of the type described above, which eliminates the above-mentioned disadvantages.

According to the invention, this object is achieved in that the control valve consists of a slide disposed axially slidably in a sealed valve chamber, in a plane extending substantially perpendicular to the sliding direction of the slide, At least one opening is provided in the wall for communication between the valve chamber space and the delivery chamber, and the valve chamber spaces on either side of said at least one opening are provided with connectors for connection to the suction chamber and the pressure pipe, respectively. This is achieved in that, between the end positions of the slide, the sealing portion thereof which engages the valve chamber wall is at least partially open to the several ports.

By using this volume control valve, a check valve between the delivery chamber and the pressure pipe is no longer necessary. This is because, in the recirculating state of the compressor, the control valve automatically disconnects the pressure pipe and the delivery chamber.

Since the sealing part of the slide moves quickly from end to end and usually does not remain in an intermediate position, there is no pressure buildup that is too high.

Preferably, in the sliding direction, the sealing portion of the slide is smaller than the dimension of the mouth (the length of the axial mouth).

This further ensures that upon final closure of the slide in the intermediate position, the several ports are never completely closed, and therefore too much pressure builds up that the delivery chamber ruptures. to prevent.

In a preferred embodiment, the slide has a second sealing surface that engages the valve chamber wall and is connected to the first sealing surface. Since the space between the sealing surfaces (circumferential depression) is always in communication with the suction chamber, the pressures on the surfaces facing each other are equal. Since the space in front of the slide intertwines with the space behind the slide, the pressures on the surfaces facing each other are equal.

In this embodiment, the control valves are fully balanced so that the slide can operate with low energy.

On the end face of the slide facing away from the valve chamber space communicating with the pressure pipe, in this embodiment a magnetizable armature is mounted coaxially and cooperates with a coaxially arranged electric coil. are doing.

Preferably a biasing spring is provided to bias the slide away from the valve chamber space communicating with the pressure pipe. The space in which the electric coil is arranged is adjacent to the delivery chamber.

In this embodiment, the control valve is energized in the compressor recirculation condition. This provides the advantage that in the energized state of the coil it is cooled by the refrigerant in the delivery chamber and has a relatively low temperature during recirculation.

The invention will now be described with reference to the drawings, in which preferred embodiments of the invention are shown.

Although a piston-type compressor is shown in the drawings, it is clear that the displacement control valve according to the invention can also be applied to other types of compressors. Such piston compressors are often applied in refrigeration installations where the refrigerant Freon or aluminium gas is used. The capacity control valve according to the invention appears to be suitable for other applications as well.

The compressor consists of a suction chamber 1 and a delivery chamber 2 in the compressor head. The control valve is mounted on the head and immediately adjacent to the delivery chamber 2. The above control valve has cylindrical valve chambers 3, 4,
5 and 6, and a slide slidable therein in the axial direction. The right-hand side 3 of the valve chamber communicates with a space 8 to which a pressure pipe, not shown in the drawing, can be connected.

Several ports 9 are provided in the valve chamber wall, communicating the valve chamber with the delivery chamber 2. The part of the valve chamber in which the mouth 9 is provided is formed by the lining 10 of the cylinder pushed into the valve chamber, the wall of which is perforated. The opening 9 is surrounded by a ring-shaped space 11 that can be considered as an extension of the delivery chamber 2. Removable cylinder lining 10
By using the aperture 9 is provided in a simple manner.

The cylindrical slide 7 has two ring-shaped sliding surfaces 12,13. The first sealing surface 12 engages with the inner wall of the cylinder lining 10, while the second sealing surface 13 engages with the cylindrical wall of the valve chamber 4.
Any known sealing means can be applied for effective sealing.

The slide 7 is slidable from the indicated position on the left hand side of the mouth to the right and vice versa.

A recess 14 is provided between the sealing surfaces 12, 13, in which the space 4 is closed by the surface of the recess and the valve chamber wall. Slide 7 in this space
Connect the connecting conduit 15 in such a position that no matter what position it is in, the connecting conduit 15 always appears in the space 4 defined by the recess 14. This communication conduit 15 extends into the suction chamber 1 . The connection between the space 4 and the suction chamber 1 can also be achieved through passages in the head and compressor housing.

The control valve is shown in a compressed state. piston 1
6 and 17 absorb refrigerant from the suction chamber 1 and send it to the delivery chamber 2. Piston compressors are generally known, so there is no need to discuss them in further detail. The refrigerant is compressed from the delivery chamber 2 via the port 9 and the space 8 and enters a pressure pipe (not shown).

When the compressor is put into recirculation by actuating the control valve, the slide 7 is moved from left to right until the first sealing surface 12 is in a position beyond the mouth 9. In this state of recirculation, a refrigerant path is established extending from the suction chamber 1 to the delivery chamber 2, the opening 9, the space 4 formed by the recess 14, the communicating guide 15 and again to the suction chamber. is recirculated by the pistons 16, 17, but no refrigerant is transported into the space 8.

However, there is a possibility that the slide 7 becomes blocked in some way and becomes stuck. No problem occurs when the sealing surface 12 is on the right hand side of the mouth 9 in the closed state. This is because the compressor remains in a non-hazardous recirculating condition. Also, no problem will occur when the sealing surface 12 sticks to the left side of the mouth 9. This is because the container connected to the pressure pipe, which is not shown, must be provided with overpressure protection according to regulations. However, the intermediate occluded position presents a problem since the mouth 9 can be completely closed off by the sealing surface 12. When the mouth 9 is closed with the first sealing surface in the closed intermediate position, the compressor can rupture due to the pressure created in the delivery chamber 2. This problem is caused by the first sealing surface 12
in the direction of sliding is smaller than the dimension of the opening 9 measured in the same direction. No position of the slide 7 is possible where this would result in the mouth being closed. Thus,
In an intermediate position the passage opens into the suction chamber 1 or into the space 8 or into both.

It is noted that balanced valves are known per se. By configuring the slide 7 with said recess 14 in such a way that the communicating conduit 15 always appears in the space 4 formed by the recess 14, the slide always has a communicating conduit 15 established in the suction chamber 1. There is always a balance with respect to the pressure transferred to the slide 7 via the slide 7. Balancing of the slide is optimal when the opposing surfaces 18, 19 of the recess 14 extending transversely to the axis of the slide 7 to the sealing parts 12 and 13 have equal cross-sectional areas within the seal.

Equilibration with respect to the pressure in the space 8 acting on the right-hand side 20 of the slide 7 is obtained by a continuous passage extending from the right-hand end face 20 to the left-hand end face 21 of the slide 7. In the illustrated embodiment, the above-mentioned passage is formed by the gap between the operating rod 22 and the hole 23 of the slide 7. In order to create the above-mentioned balancing, the operating rod 22 may also be hollow and may be provided with a lateral opening at a position towards the space 5. A solution to the latter is not shown. This is because it is already sufficiently clear in itself. Due to the passages described above, the pressure on the respective left-hand end face 21 and right-hand end face 22 of the slide 7 is equal, and because they have equal cross-sectional areas within the seal, the slide 7 is substantially balanced with respect to pressure. Disturbances occur when the cross-sectional areas of the rods are different.

The sliding movement of the slide 7 can be controlled in any manner, for example pneumatically. In the illustrated embodiment, the slide is preferably operated electromagnetically, resulting in the advantage of complete equilibration of the slide.

The electromagnetic control mechanism consists of a coil 24 energized through an electrical conductor 25. Said coil 24 is arranged in the left hand part 6 of the chamber of the control valve and is enclosed between a bush 26 and a cover 27. O-ring 28 and bushing 35 separate the coil space from spaces 30, 36, and 5. electric coil 2
An armature 29 made of magnetizable material is partially accommodated in the interior space of 4 and can be slid axially therein. The armature 29 is screwed into the operating rod 22 of the slide 7. The armature 29 is alternatively slidably supported in a recess 30 in the cover 27. Support can be provided in holes 31. The sliding of the armature 29 is the coil 2
This is done by the bias of 4.

A small portion 31 of the hole in the bush 26 has a relatively small diameter. The remaining portion 32 of the hole in the bushing 26 has a biased spring 33
It has a larger diameter to accommodate one end of the. The other end of the spring 33 is supported on the right hand side of the armature 29. To balance, bush 2
A gap may be provided between the hole portion 31 of No. 6 and the operating rod 22. The armature is also accommodated in the armature guide recess 30 with a small gap in order to achieve perfect balance of the armature. This means that there is an equal pressure in spaces 5, 8, 36 and 30 so that the slides are completely balanced.

As can be seen from the figures, the valve chamber is located adjacent to the delivery chamber 2, while the slide 7 is biased towards its compressed position. Thereby, when the coil 24 is energized and thus heated, it is cooled by the refrigerant in the air 2 discharged through the wall 34 of the compressor head;
This refrigerant has a lower temperature than the coil. This is because with the energized coil the compressor is in its recirculation condition. This is because under these conditions the relatively cooled solvent coming from the suction chamber 1 flows through the delivery chamber 2.

Although the invention has been described with reference to the preferred embodiments shown in the figures, it will be obvious that certain modifications may be made within the scope of the invention.

[Brief explanation of drawings]

The drawing shows a cross section of a preferred embodiment of the piston compressor of the invention. 1... Suction chamber, 2... Delivery chamber, 3... Valve chamber, 4... Valve chamber, 5... Valve chamber, 6... Valve chamber, 7...
... Cylindrical slide, 8 ... Pressure pipe connection cavity, 9 ... Port, 10 ... Cylinder lining,
11...Ring-shaped chamber, 12...Ring-shaped sealing surface, 13...Ring-shaped sealing surface, 14...Indentation,
15... Connecting guide conduit, 16... Piston, 17... Piston, 18... Opposing surfaces of the recess, 19... Opposing surfaces of the recess, 20... Right hand surface of the slide, 21... Left hand surface of the slide, 22... Operating rod, 23, Hole in the slide, 24
... Coil, 25 ... Electric conductor, 26 ... Bush, 27 ... Cover, 28 ... O-ring, 29
... Armature, 30 ... Space, 3
1... part of the hole in the bush, 32... remaining part of the hole, 33... spring, 34... wall of compressor head, 35... bush, 36... space.

Claims (1)

[Claims] 1. A capacity control valve for a compressor, comprising a suction chamber and a delivery chamber connected to a pressure pipe and having valve means controlled by a control valve between the connection to the pressure pipe. The control valve comprises a sealed valve chamber and a slide slidable in the axial direction in the sealed valve chamber, and the sealed valve chamber includes a valve for communicating between the internal space of the valve chamber and the delivery chamber. At least one port is provided in the wall of the sealed valve chamber in a virtual plane position extending substantially perpendicular to the sliding direction of the slide, and each side of the at least one port in the space of the sealed valve chamber is provided with a suction port. The slide is in communication with the chamber and the connector of the pressure pipe, and the slide has a first sealing part that moves on the sealing valve chamber wall on both sides of the mouth, and a second sealing part that moves on the sealing valve chamber wall. A circumferential recess perpendicular to the axis of the slide is provided between the first sealing portion and the second sealing surface, and the axial dimension of the recess is such that the slide has a sealing surface. In any position, the recess is longer than the stroke of the slide so as to communicate with the connection to the suction chamber, and the mutually facing surfaces of the recess have substantially equal areas and the sealing portion of the slide is The end surface and the outside of the end surface of the second sealing surface are connected by a communicating passage, and at both end positions of the slide stroke, the above-mentioned sealing portion of the slide that is in contact with the wall of the sealing valve chamber is at least partially A valve characterized by having an open mouth. 2. Capacity control valve according to claim 1, characterized in that in the sliding direction, the sealing part of the slide is smaller than the size of the mouth. 3. On the end face of the slide opposite the sealed valve chamber space connected to the pressure pipe, a magnetizable armature cooperates with a coaxially arranged electric coil mounted coaxially. A capacity control valve according to any one of claims 1 to 2. 4. A biasing spring is provided for biasing the slide in a direction opposite to the sealed valve chamber space communicating with the pressure pipe, and the space in which the electric coil is located is adjacent to the delivery chamber. The capacity control valve according to item 3.