FR2795781A1 - OUTLET VALVE FOR SCROLL COMPRESSOR - Google Patents

Abstract

This valve comprises a tubular body (23), of which the opposite end to the pipe (16) that brings in gas to the delivery chamber is closed, this body comprising a cavity which has a first portion (25) for guiding the shut-off leaf (32) and a second portion (26) in permanent communication with the delivery chamber. The body comprises, in the first portion (25), radial openings (28) which open into the delivery chamber.

Description

The present invention relates to a discharge valve for a scroll compressor.

A scroll compressor is shown in Figure 1 of the accompanying schematic drawing. This compressor comprises a hermetic envelope 2, inside which are provided a suction chamber 3 provided with an inlet 4 for the gas, and a discharge chamber or pressure chamber 5 provided with an outlet 6 for the gas. The suction 3 and discharge 5 chambers are separated by a partition wall 7. Inside the suction chamber 3 is mounted an electric motor, the stator 8 and the rotor 9 of which are shown diagrammatically in the drawing. The rotor 9 is associated with a shaft 10 guided in rotation in lower 12 and upper bearings 13. the pump intended to ensure the pressure build-up of the gas consists of two volutes, a volute 14 belonging to the partition wall 7, and a movable volute 15 driven by the drive shaft 10 and eccentric with respect to this shaft to delimit, during an orbital movement, pockets of variable and increasingly small volume, in which the gas is compressed before s escape through an outlet orifice 16 towards the discharge chamber 5. A valve system designated by the general reference 17 is mounted on the outlet 16, in order to allow the passage of the gas towards the pressure chamber, and avoid the passage of gas from this same chamber to the suction chamber.

Known valves have different structures. In a first case, it is a free valve which is mounted sliding, or articulated. A disadvantage of this type of valve is that the oil inside the compressor being diffused in the form of an aerosol on the various parts, an oil film is formed which ensures "sticking" of the valve in position d opening, so that when the compressor is stopped, pressurized gas contained in the high pressure chamber can pass into the suction chamber where the pressure is lower, and drive the rotating parts of the machine in operation back. In addition to a closure that is not secure, there are, in some cases, beat phenomena disturbing the operation of the compressor, affecting its performance, and generating unpleasant noise for those around.

It is also known to use lamella valves, such a lamella being constituted by a spring blade which opens at each compression peak and whose elasticity ensures closure between two peaks. This technique can be justified in the field of refrigeration, given an improvement in performance, but is not justified in the field of air conditioning. This technique generates significant noise resulting from the beating of the coverslip during each of its movements.

Document US-A-5 494 422 relates to a scroll compressor equipped with a discharge valve comprising a tubular body, fixed on the face of the partition wall between the suction chamber and the discharge chamber, one end of this body being open and in communication with the outlet duct of the compression stage, and its other end being open and communicating with the discharge chamber, a shutter blade with a surface at least equal to that of the opening of the outlet duct of the compression stage and movable parallel to itself between a closed position in which it closes this conduit and an open position in which it is in abutment against a seat formed in the tubular body, and at least one opening radial formed in the body between the part forming a seat for the blade, in the open position, and the wall delimiting the opening of the outlet duct of the compression stage we.

When the pressure of the discharged fluid drops, the obturator blade should be detached from its seat to switch to its closed position, since the pressure in the discharge chamber is then greater than the pressure in the tubular body. However, this operation is very theoretical due to the existence of a virtually instantaneous pressure balance between the tubular body and the delivery chamber. The blade is therefore not, in reality, subjected to a pressure difference facilitating its movement towards the closed position.

The object of the invention is to provide a discharge valve for scroll compressor, which ensures immediate closure of the communication between the suction chamber and the discharge chamber when the compressor stops, which has excellent stability during oscillating flows, including if the compression rate is higher than the geometric compression rate, and which reduces the radiated noise of the compressor. To this end, the discharge valve which it relates to, of the type comprising - a tubular body, fixed on the face of the partition wall between the suction chamber and the discharge chamber or on a plate, attached to this wall , one end of this body being open and in communication with the outlet duct of the compression stage, - a shutter blade with a surface at least equal to that of the opening of the outlet duct of the compression stage and movable parallel to itself between a closed position in which it closes this duct and an open position in which it bears against a seat formed in the tubular body, - at least one radial opening formed in the body between the part forming a seat for the blade, in the open position, and the wall delimiting the opening of the outlet duct of the compression stage, is characterized in that it comprises a chamber which, e in the body on the side thereof situated between the part forming a seat for the blade in the open position and the bottom of the body, has a section smaller than that of the obturator blade and communicates with the delivery chamber by at least an orifice formed in the bottom of the body and whose section is small compared to that of this bottom.

In practice, when the compressor is operating, the pressure of the gas coming from the compression stage causes the shutter blade to move, and to bear against the seat formed in the tubular body. The blade remains held against this seat thanks to the presence of an oil film, which avoids the phenomena of flapping resulting from instantaneous closings during each compression peak. Air escapes radially through the openings in the body, this arrangement significantly improving soundproofing compared to the known device. In addition, in the chamber located between the bottom of the body and the obturator blade, in the open position of the valve, there is a pressure equal to the pressure inside the discharge chamber. However, given the fact that this pressure is exerted only on a surface less than that of the total surface of the blade, it does not risk causing the passage of the latter in the closed position of the valve. However, as soon as the compressor stops, that is to say that the pressure at the compression stage drops, the pressure located in the chamber of the valve body, in communication with the discharge chamber, being significantly higher than the pressure on the other side of the shutter blade, it is immediately moved to the closed position of the valve. In fact, the pressure in the chamber located in the body of the valve drops much less quickly than the pressure inside the discharge chamber, taking into account the small cross-section of the orifices for connecting these two chambers.

Thus, the diameter of each orifice formed in the bottom of the tubular body is less than or equal to 2 mm, while the diameter of the chamber is of the order of 25 to 30 mm, for example.

In addition, the passage section of the radial openings in communication between the interior of the tubular body and the discharge chamber decreases from the chamber of the tubular body towards the discharge chamber, one of the characteristic dimensions delimiting this section being small.

The value of the characteristic dimension which is small can be between 0 and 1 mm.

According to a first embodiment of this valve, the obturator blade is constituted by a circular disc, while the tubular body has an internal cavity of circular section and having two successive sections of different diameters, that is to say of the side of its open end a section of diameter substantially equal to the diameter of the obturator blade, extended by a section of smaller diameter, these two sections being connected by a shoulder, forming a seat for the blade, in the open position of the valve, radial openings being arranged in the body, between the shoulder and the open end of the body.

The radial openings formed in the body may be formed by holes or by recesses opening into the edge of the body bearing against the wall of the compressor separating the suction chamber and the discharge chamber.

According to an advantageous characteristic of the invention, the body comprises, outside the tubular part in which is formed at least one radial opening, a peripheral skirt, delimiting with the tubular part an annular chamber, the section of which decreases from the tubular part, in the radial direction towards the outside, and communicates towards the outside by a slot, formed between the skirt and the partition wall between the suction chamber and the discharge chamber, or a plate fixed on this wall.

This annular chamber, the section of which decreases from the inside to the outside, provides very high noise damping making the operation of the compressor particularly silent.

According to another characteristic, in the part of the body forming a seat for the blade, in the open position of the valve, open holes for communication with the delivery chamber. Advantageously, the section of the holes opening into the seat increases in the direction of the delivery chamber. This arrangement, when the compressor stops, and due to the pressure prevailing in the chamber located on the side of the bottom of the body, makes it possible to detach the obturator blade from its seat, and to accelerate the movement of the obturator blade towards its closed position, allowing a large volume of gas to pass through these holes.

According to another embodiment of this valve, the outlet orifice of the compression stage has an annular shape or is constituted by several holes, arranged in a crown, the obturator blade has a corresponding annular shape, and the body comprises an annular cavity, of section decreasing in radial direction towards the outside, the outermost edge of the body delimiting a slot or openings with the partition wall between the suction chamber and the discharge chamber, or a fixed plate on this wall, the annular cavity having, on the side of its bottom, a seat forming a seat for the obturator blade, in the open position of the valve, and into which an annular cavity of smaller cross-section communicates through at least one orifice, with the delivery chamber.

In this case, the fixing of the valve on the separation plate can be central. In this case also, perfect damping of the sounds is achieved by reducing the section of the annular cavity of the body, in the direction of flow of the gas.

In any case, the invention will be clearly understood with the aid of the description which follows, with reference to the appended diagrammatic drawing representing, by way of nonlimiting examples, several embodiments of this discharge valve for scroll compressor. Figure 1 is a principle view, in longitudinal section of a scroll compressor; Figure 2 is an exploded perspective view of a first valve, and of the separation plate between the suction chamber and the discharge chamber; Figure 3 is a sectional view, through a diametrical plane, of the device of Figure 2; Figure 4 is a diametral sectional view on an enlarged scale of the valve of Figure 2; Figures 5 and 6 are two views respectively in exploded perspective and in section through a diametrical plane of a second valve; Figure 7 is a perspective view of the interior of the valve body of Figures 5 and 6; Figure 8 is a view of the same valve in diametral section and on an enlarged scale; Figures 9 and 10 are two views respectively in perspective and in section, through a diametrical plane, of a third valve.

FIG. 2 represents a first valve comprising, mounted on a plate 22 fixed to the wall 7 of separation between the suction chamber and the discharge chamber, a body 23 fixed by screwing at the level of a peripheral flange 24. The body 23 includes an interior cavity having two successive sections 25 and 26, of circular section, and connected by a shoulder 27, the section 26 being of section smaller than that of the section 25. The section 25 is situated on the side of the open end, equipped with the flange 24, while the section 26 is located on the closed side of the cavity. In the peripheral wall of the body, and between the shoulder 27 and the open end, openings 28 are regularly distributed, bringing the internal cavity of the body into communication with the delivery chamber. In the bottom 29 of the body 23 is formed an orifice 30 for communicating the bottom of the cavity with the delivery chamber. The cavity is used to house a shutter blade 32 in the form of a disc, of section at least equal to the orifice to be closed, and of diameter corresponding to that of the section 25 of larger section of the cavity.

The operation of this valve is as follows: when the compressor is operating, the gas pressure moves the valve 32 from its position of support against the plate 22, where it closes the conduit 16, towards a position in which it is in support against the shoulder 27 forming a seat. The support against this shoulder is ensured by "bonding" by the oil film existing during pressure variations resulting from compression peaks. The gas can pass from the compression stage to the discharge chamber through the openings 28. The bottom of the body cavity, corresponding to the section 26, is then in communication with the discharge chamber 30. However, taking into account the balance of pressures on both sides of the shutter blade 32, it remains pressed remains pressed against its seat. When the compressor stops, the pressure below the obturator blade 32 drops suddenly, and the pressure prevailing in the section of cavity 26, equal to the pressure of the discharge chamber, ensures an immediate displacement of the obturator blade towards its support position against the plate 22 with closing of the conduit 16, that is to say the closed position of the valve.

Figures 5 to 8 show an alternative embodiment of this valve, in which the same elements are designated by the same references as above.

In this embodiment, the body comprises, outside the tubular part in which the radial openings are formed, a peripheral skirt 33 delimiting with the tubular part an annular chamber 34 whose section decreases from the tubular part in the direction radial towards the outside and communicates towards the outside with the delivery chamber by a slot 35 formed between the skirt and the plate 22. It should be noted that the radial openings opening into the first section 25 are not holes, but recesses 36 opening into the lower edge of the tubular part.

In this case, the attachment to the plate is achieved by screwing using screws 31 through holes 37 formed in the part 33 in the form of a skirt. In this valve, holes 38 opening into the shoulder 27 forming a seat ensure communication with the delivery chamber. These holes 38 widen on the side of the delivery chamber. The operation of this valve is similar to the operation of the valve described above with reference to FIGS. 2 to 4. The essential difference results in the fact that the annular chamber 34, the cross section of which decreases in the direction of gas flow, provides damping of the compressor operating noise. In addition, when the compressor stops, after the shutter blade 32 has taken off from the seat under the action of the pressure prevailing in the section 26 of the body cavity, the passage of pressurized gas through the holes 38 accelerates. the movement of the obturator blade towards its closed position.

Figures 9 and 10 show another alternative embodiment of this valve, in which the same elements are designated by the same references as above. In this case, the outlet of the gas from the compression stage is achieved by three elongated slots 39 arranged in a ring. The obturator blade 40 has a corresponding annular shape and the body 42 of the valve comprises an annular cavity 43 of section decreasing in radial direction towards the outside, the outermost edge 44 of the body delimiting a slot 45 with the plate 22 fixed on the partition wall. The annular cavity 43 has, on the side of its bottom, a bearing surface 46 forming a seat for the obturator blade 40, in the open position of the valve. In this range 46, an annular cavity 47 of smaller section opens communicating through an orifice 48 with the delivery chamber. The central part 49 of the valve body is used for fixing the latter using a screw-nut system 50 on the plate 22.

This valve works in the same way as the valves described above. When the compressor is stopped, the shutter blade 40 closes the openings 39. When the compressor is running, the pressure moves the shutter blade 40 to apply it against the seat 46 formed at the bottom of the cavity. The gas can then flow through the cavity 43, and pass from the latter into the delivery chamber through the slot 45. When the compressor stops, the pressure prevailing in the annular chamber 47 makes it possible to take off the blade. shutter and ensuring the passage thereof to its closed position. As in the case of the previous embodiment described, the reduction in section of the annular chamber 43 ensuring the passage of the gas considerably reduces the operating noise of the compressor.

As is apparent from the above, the invention brings a great improvement to the existing technique by providing a discharge valve for scroll compressor having excellent stability during operation, ensuring immediate closure when the compressor stops, and providing a significant reduction in compressor operating noise.

As it goes without saying, the invention is not limited to the sole embodiments of this discharge valve, described above by way of nonlimiting examples, on the contrary it embraces all variants. Thus in particular that the plate 22 could be omitted, its structure being integrated in the separation plate between the suction chamber and the discharge chamber, or even that the size of the body could be different and more present the shape of 'A plate, or finally that the number and / or the shape of the slots and openings could be different without departing from the scope of the invention.

Claims (8)

<B> CLAIMS </B> 1. Discharge valve for scroll compressor, intended to be mounted at the downstream end of an outlet duct from the compression stage consisting of a fixed volute and a volute driven by an orbital movement, and located at inlet of the high pressure chamber or discharge chamber of the compressor, of the type comprising - a tubular body (23, 42), fixed on the face of the wall (7) of separation between the suction chamber and the discharge chamber or on a plate (22), attached to this wall, one end of this body being open and in communication with the outlet duct (16) of the compression stage, - a sealing blade (32, 40) having at least a surface equal to that of the opening of the outlet stage (16) of the compression stage and movable parallel to itself between a closed position in which it closes this duct and an open position in which it is supported against a seat (27, 46) m in the tubular body, - at least one radial opening (28, 35, 36, 45) formed in the body between the seat part (27, 46) for the blade, in the open position, and the wall defining the opening of the outlet stage of the compression stage, characterized in that it comprises a chamber (26, 47) which, formed in the body (23, 42) on the side thereof situated between the seat part (27, 46) for the blade (32, 40) in the open position and the bottom of the body, has a smaller section than that of the obturator blade and communicates with the delivery chamber through at least one orifice (30, 48 ) formed in the bottom of the body and whose section is small compared to that of this bottom. 2. Valve according to claim 1, characterized in that the diameter of each orifice (30, 48) formed in the bottom of the tubular body is less than or equal to 2 mm. 3. A valve according to any one of claims 1 and 2, characterized in that the passage section of the radial openings for communication between the interior of the tubular body (23, 42) and the delivery chamber decreases from the chamber of the tubular body towards the discharge chamber, one of the characteristic dimensions delimiting this section being small. 4. Valve according to one of claims 1 to 3, characterized in that the obturator blade is constituted by a circular disc (32), while the tubular body (23) has an internal cavity of circular section and having two successive sections of different diameters, that is to say on the side of its open end, a section (25) of diameter substantially equal to the diameter of the obturator blade (32), extended by a section (26) of smaller diameter, these two sections (25, 26) being connected by a shoulder (27), forming a seat for the blade (32), in the open position of the valve, radial openings (28, 36) being formed in the body (23), between the shoulder (27) and the open end of the body. 5. Valve according to any one of claims 1 and 2, characterized in that the body (23) comprises, outside the tubular part (25) in which is formed at least one radial opening (36), a peripheral skirt (33), delimiting with the tubular part an annular chamber (34), the section of which decreases from the tubular part (25), in the radial direction towards the outside, and communicates towards the outside by a slot (35) , formed between the skirt (33) and the partition wall between the suction chamber and the discharge chamber, or a plate (22) fixed on this wall. 6. Valve according to one of claims 1 to 3, characterized in that the outlet orifice of the compression stage has an annular shape or is constituted by several holes (39), arranged in a crown, the obturator blade (40) has a corresponding annular shape, and the body has an annular cavity (43), of section decreasing in radial direction towards the outside, the outermost edge (44) of the body delimiting a slot (45) or openings with the partition wall between the suction chamber and the discharge chamber, or a plate (22) fixed on this wall (7), the annular cavity (43) having, on the side of its bottom, a bearing surface (46) forming a seat for the obturator blade (40), in the open position of the valve, and into which opens an annular cavity (43) of smaller section communicating through at least one orifice (48), with the delivery chamber. 7. Valve according to one of claims 1 to 6, characterized in that, in the part of the seat body (27), for the blade, in the open position of the valve, open holes (38) in communication with the discharge chamber. 8. Valve according to claim 7, characterized in that the section of the holes (38) opening into the seat (27) increases in the direction of the discharge chamber.