Scroll compressor having first and second oldham couplings

This scroll compressor includes a first fixed scroll member, an orbiting scroll arrangement including a first orbiting scroll member, a first Oldham coupling provided between the first orbiting scroll member and the first fixed scroll member and configured to prevent rotation of the first orbiting scroll member with respect to the first fixed scroll member, a fixed element opposite to the first fixed scroll member with respect to the orbiting scroll arrangement, and a second Oldham coupling provided between the orbiting scroll arrangement and the fixed element and configured to prevent rotation of the orbiting scroll arrangement with respect to the fixed element. The first Oldham coupling is slidable with respect to the first fixed scroll member along a first displacement direction, and the second Oldham coupling is slidable with respect to the fixed element along a second displacement direction transverse to the first displacement direction.

FIELD OF THE INVENTION

The present invention relates to a scroll compressor, and in particular to a scroll refrigeration compressor.

BACKGROUND OF THE INVENTION

As known, a scroll compressor comprises:a fixed scroll member comprising a fixed end plate and a fixed spiral wrap provided on one face of the fixed end plate,an orbiting scroll member comprising an orbiting end plate and an orbiting spiral wrap provided on one face of the orbiting end plate, the fixed spiral wrap and the orbiting spiral wrap forming a plurality of compression chambers,a support frame, also named crankcase, on which is slidably mounted the orbiting end plate of the orbiting scroll member,an Oldham coupling provided between the orbiting scroll member and the support frame, and configured to prevent rotation of the orbiting scroll member with respect to the support frame, the Oldham coupling being slidably mounted with respect to the support frame along a first displacement direction,a drive shaft adapted for driving the orbiting scroll member in an orbital movement, andan electric motor for driving in rotation the drive shaft about a rotation axis.

In order to reduce the compressor vibrations generated by the reciprocating translation movement of the Oldham coupling along the first displacement direction, the scroll compressor further comprises a rotating counterweight attached to the drive shaft.

However, the unbalance induced by the reciprocating translation movement of the Oldham coupling cannot be perfectly compensated thanks to a rotating counterweight, which leads to the presence of a residual unbalance, and thus of residual compressor vibrations. Such residual compressor vibrations may cause a damage of some parts of the scroll compressor, and may detract the efficiency of the scroll compressor.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved scroll compressor which can overcome the drawbacks encountered in conventional scroll compressors.

Another object of the present invention is to provide a scroll compressor which is reliable and which can be easily balanced.

According to the invention such a scroll compressor comprises:a first fixed scroll member comprising a first fixed end plate and a first fixed spiral wrap provided on one face of the first fixed end plate,an orbiting scroll arrangement including at least a first orbiting scroll member comprising a first orbiting end plate and a first orbiting spiral wrap provided on one face of the first orbiting end plate, the first fixed spiral wrap and the first orbiting spiral wrap forming a plurality of first compression chambers,a first Oldham coupling provided between the first orbiting scroll member and the first fixed scroll member, and configured to prevent rotation of the first orbiting scroll member with respect to the first fixed scroll member, the first Oldham coupling being slidable with respect to the first fixed scroll member along a first displacement direction,a second Oldham coupling configured to prevent rotation of the orbiting scroll arrangement with respect to the first fixed scroll member, the second Oldham coupling being slidable with respect to the first fixed scroll member along a second displacement direction,wherein the first and second displacement directions of the first and second Oldham couplings are substantially orthogonal with respect to each other.

Due to the transverse movements of the first and second Oldham couplings, the centers of gravity of the first and second Oldham couplings can be assimilated to a rotating mass, which can be easily balanced by a rotating counterweight attached to the drive shaft. Therefore, the compressor vibrations generated by the translation movements of the first and second Oldham couplings can be greatly reduced. Such a limitation of the compressor vibrations leads to an improvement of the compressor reliability and efficiency.

According to an embodiment of the invention, each of the first and second Oldham couplings undergoes a reciprocating motion respectively along the first and second displacement directions.

For example, the first and second displacement directions of said first and second Oldham couplings may be orthogonal with respect to each other, or may be inclined by an angle comprised between 80 and 100°, and preferably between 85 and 95°.

According to an embodiment of the invention, the first and second Oldham couplings are configured such that, in operation, the resulting center of gravity of the first and second Oldham couplings is moving along a circular trajectory.

According to an embodiment of the invention, the scroll compressor further comprises a drive shaft adapted for driving the orbiting scroll arrangement in an orbital movement, and a motor for driving in rotation the drive shaft about a rotation axis.

According to an embodiment of the invention, the first and second displacement directions are substantially perpendicular to the rotation axis of the drive shaft.

According to an embodiment of the invention, the center of the circular trajectory is substantially located on the rotation axis of the drive shaft. This arrangement of the first and second Oldham couplings allows to cancel the residual unbalance due to the first and second Oldham couplings movements, and thus to greatly improve the balance the compressor.

According to an embodiment of the invention, the first and second Oldham couplings are configured such that the middle-stroke positions of the centers of gravity of the first and second Oldham couplings are substantially located on the rotation axis of the drive shaft.

According to an embodiment of the invention, the scroll compressor further comprises a counterweight attached to the drive shaft and intended to balance the total mass of the first and second Oldham couplings.

According to an embodiment of the invention, the center of gravity of the counterweight is substantially diametrically opposed to the resulting center of gravity of the first and second Oldham couplings and of the orbiting scroll arrangement with respect to the rotation axis of the drive shaft.

According to an embodiment of the invention, the stroke length of the first Oldham coupling along the first displacement direction is substantially equal to the stroke length of the second Oldham coupling along the second displacement direction.

According to an embodiment of the invention, the first and second Oldham couplings respectively include first and second annular bodies that are substantially parallel to each other.

According to an embodiment of the invention, the first Oldham coupling includes:a first annular body,a first pair of first engaging projections provided on a first side of the first annular body, the first engaging projections of the first Oldham coupling being slidably engaged in a first pair of first guiding grooves provided on the first fixed scroll member, said first guiding grooves being offset and extending substantially parallel to the first displacement direction, anda second pair of second engaging projections provided on a second side of the first annular body, the second engaging projections of the first Oldham coupling being slidably engaged in a second pair of second guiding grooves provided on the first orbiting scroll member, said second guiding grooves being offset and extending substantially perpendicularly to the first displacement direction.

According to an embodiment of the invention, the first annular body is disposed around the first fixed spiral wrap and the first orbiting spiral wrap.

According to an embodiment of the invention, the first engaging projections of the first Oldham coupling extend substantially perpendicularly from the first side of the first annular body and the second engaging projections of the first Oldham coupling extend substantially perpendicularly from the second side of the first annular body.

According to another embodiment of the invention, the first pair of first engaging projections may be provided on the first fixed scroll member, and the first pair of first guiding grooves may be provided on the first side of the first annular body.

According to another embodiment of the invention, the second pair of second engaging projections may be provided on the first orbiting scroll member, and the second pair of second guiding grooves may be provided on the second side of the first annular body.

Thus, for example, the first annular body may comprise the first pair of guiding grooves on its first side and the second pair of second guiding grooves on its second side. The first annular body may also comprise a pair of engaging projections on one of its first and second sides and a pair of guiding grooves on its other side.

According to an embodiment of the invention, the scroll compressor further comprises a fixed element opposite to the first fixed scroll member with respect to the orbiting scroll arrangement, the second Oldham coupling being provided between the orbiting scroll arrangement and the fixed element and configured to prevent rotation of the orbiting scroll arrangement with respect to the fixed element, the second Oldham coupling being slidable with respect to the fixed element along the second displacement direction.

According to an embodiment of the invention, the second Oldham coupling includes:a second annular body,a first pair of first engaging projections provided on a first side of the second annular body, the first engaging projections of the second Oldham coupling being slidably engaged in a first pair of first guiding grooves provided on the fixed element, said first guiding grooves being offset and extending substantially parallel to the second displacement direction, anda second pair of second engaging projections provided on a second side of the second annular body, the second engaging projections of the second Oldham coupling being slidably engaged in a second pair of second guiding grooves provided on the orbiting scroll arrangement, said second guiding grooves being offset and extending substantially perpendicularly to the second displacement direction.

According to an embodiment of the invention, the first engaging projections of the second Oldham coupling extend substantially perpendicularly from the first side of the second annular body and the second engaging projections of the second Oldham coupling extend substantially perpendicularly from the second side of the second annular body.

According to another embodiment of the invention, the first pair of first engaging projections may be provided on the fixed element, and the first pair of first guiding grooves may be provided on the first side of the second annular body.

According to another embodiment of the invention, the second pair of second engaging projections may be provided on the orbiting scroll arrangement, and the second pair of second guiding grooves may be provided on the second side of the second annular body.

Thus, for example, the second annular body may comprise the first pair of guiding grooves on its first side and the second pair of second guiding grooves on its second side. The second annular body may also comprise a pair of engaging projections on one of its first and second sides and a pair of guiding grooves on its other side.

According to an embodiment of the invention, the fixed element is formed by a support frame on which is slidably mounted the first orbiting end plate of the first orbiting scroll member.

According to an embodiment of the invention, the scroll compressor further comprises a closed casing and a suction inlet, the closed casing and the support frame defining a low pressure volume into which opens the suction inlet.

According to an embodiment of the invention, the second Oldham coupling is provided between the support frame and the first orbiting end plate.

According to an embodiment of the invention, the second guiding grooves in which are slidably engaged the second engaging projections of the second Oldham coupling are provided on the first orbiting scroll member.

According to an embodiment of the invention, the fixed element is formed by a second fixed scroll member comprising a second fixed end plate and a second fixed spiral wrap provided on one face of the second fixed end plate, and the orbiting scroll arrangement further comprises a second orbiting scroll member comprising a second orbiting end plate and a second orbiting spiral wrap provided on one face of the second orbiting end plate, the second fixed spiral wrap and the second orbiting spiral wrap forming a plurality of second compression chambers, the second Oldham coupling being provided between the second orbiting scroll member and the second fixed scroll member, and particularly between the second orbiting end plate and the second fixed end plate.

According to an embodiment of the invention, the first and second orbiting scroll members are joined or linked together.

According to an embodiment of the invention, the first and second orbiting end plates are secured to each other.

According to an embodiment of the invention, the first and second orbiting end plates are formed by a common end plate, the first and second orbiting spiral wraps being provided on opposing faces of the common end plate.

According to an embodiment of the invention, the second annular body is disposed around the second fixed spiral wrap and the second orbiting spiral wrap.

The present invention also relates to a method of operating a scroll compressor, comprising the steps of:providing the scroll compressor with:a first fixed scroll member comprising a first fixed end plate and a first fixed spiral wrap provided on one face of the first fixed end plate,an orbiting scroll arrangement including at least a first orbiting scroll member comprising a first orbiting end plate and a first orbiting spiral wrap provided on one face of the first orbiting end plate, the first fixed spiral wrap and the first orbiting spiral wrap forming a plurality of first compression chambers,a first Oldham coupling provided between the first orbiting scroll member and the first fixed scroll member, and configured to prevent rotation of the first orbiting scroll member with respect to the first fixed scroll member, the first Oldham coupling being slidable with respect to the first fixed scroll member along a first displacement direction,a second Oldham coupling configured to prevent rotation of the orbiting scroll arrangement with respect to the first fixed scroll member, the second Oldham coupling being slidable with respect to the first fixed scroll member along a second displacement direction, the second displacement direction of the second Oldham coupling being substantially orthogonal to the first displacement direction of the first Oldham coupling, anddisplacing the orbiting scroll arrangement along an orbital movement so as to displace the first and second Oldham couplings respectively along the first and second displacement directions.

According to an embodiment of the invention, the providing step further comprises providing the scroll compressor with:a drive shaft adapted for driving the orbiting scroll arrangement in the orbital movement, anda motor for driving in rotation the drive shaft about a rotation axis, and

the method further comprises the step of balancing the total mass of the first and second Oldham couplings with a counterweight attached to the drive shaft.

These and other advantages will become apparent upon reading the following description in view of the drawing attached hereto representing, as non-limiting examples, embodiments of a vehicle according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a scroll refrigeration compressor2occupying a vertical position. However, the scroll refrigeration compressor2according to the invention could occupy an inclined position, or a horizontal position, without significant modification to its structure.

The scroll refrigeration compressor2shown inFIG. 1comprises a closed housing3defined by a shell4whose top and bottom ends are respectively closed by cap5and a base6.

The scroll refrigeration compressor2also comprises a support frame7fixed in the closed housing3, the closed casing3and the support frame7defining a low pressure volume.

The scroll refrigeration compressor2further comprises a scroll compression unit8disposed above the support frame7. The scroll compression unit8has a fixed scroll member9and an orbiting scroll arrangement10. In particular the fixed scroll member9is fixed in relation to the closed housing3, and the orbiting scroll arrangement10includes an orbiting scroll member11supported by and in slidable contact with an upper face of the support frame7.

As known, the fixed scroll member9has an end plate12and a spiral wrap13projecting from the end plate12towards the orbiting scroll member11, and the orbiting scroll member11has an end plate14and a spiral wrap15projecting from the end plate14towards the fixed scroll member9. The spiral wrap15of the orbiting scroll member11meshes with the spiral wrap13of the fixed scroll member9to form a plurality of compression chambers16between them. The compression chambers16have a variable volume which decreases from the outside towards the inside, when the orbiting scroll member11is driven to orbit relative to the fixed scroll member9. The end plate12of the fixed scroll member9includes, in its central part, a discharge aperture17opening into the central compression chambers16and leading to a high pressure discharge chamber18.

The scroll refrigeration compressor2also includes a refrigerant suction inlet19opening into the low pressure volume to achieve the supply of refrigerant to the compressor, and a discharge outlet20which opens into the discharge chamber18.

The refrigeration compressor2further comprises an electric motor disposed below the support frame7. The electric motor has a rotor21provided with an axial through passage22, and a stator23disposed around the rotor21.

Furthermore the scroll refrigeration compressor2comprises a drive shaft24adapted for driving the orbiting scroll member11in an orbital movement. The drive shaft24extends into the axial through passage22of the rotor21and is rotatably coupled to the rotor21, so that the drive shaft24is driven to rotate by the rotor21about a rotation axis A. The drive shaft24comprises, at its top end, an eccentric pin25which is off-centered from the center of the drive shaft24, and which is inserted in a connecting sleeve part26of the orbiting scroll member11.

The scroll refrigeration compressor2also comprises a first Oldham coupling27which is slidably mounted with respect to the fixed scroll member9along a first displacement direction D1, and a second Oldham coupling28which is slidably mounted with respect to the support frame7along a second displacement direction D2which is substantially orthogonal to the first displacement direction D1. The first and second displacement directions D1, D2are substantially perpendicular to the rotation axis A of the drive shaft24. The first and second Oldham couplings27,28are configured to prevent rotation of the orbiting scroll member11with respect to the fixed scroll member9and the support frame7. Each of the first and second Oldham couplings27,28undergoes a reciprocating motion respectively along the first and second displacement directions D1, D2.

The first Oldham coupling27includes an annular body29disposed between the end plates12,14of the fixed and orbiting scroll members9,11, and around the spiral wraps13,15. The first Oldham coupling further includes a pair of first engaging projections31provided on a first side of the annular body29, and a pair of second engaging projections32provided on a second side of the annular body29. The first engaging projections31of the first

Oldham coupling27are slidably engaged in a pair of first guiding grooves33provided on the end plate12of the fixed scroll member9, the first guiding grooves33being offset and extending parallel to the first displacement direction D1. The second engaging projections32of the first Oldham coupling27are slidably engaged in a pair of second guiding grooves34provided on the end plate14of the orbiting scroll member11, the second guiding grooves34being offset and extending parallel to the second displacement direction D2, i.e. perpendicularly to the first displacement direction D1.

According to the embodiment of the invention shown inFIG. 2, the first and second engaging projections31,32extend respectively perpendicularly from the first and second sides of the annular body29.

The second Oldham coupling28includes an annular body35disposed between the support frame7and the end plate14of the orbiting scroll member11. The annular body35of the second Oldham coupling28extends substantially parallel to the annular body29of the first Oldham coupling27.

The second Oldham coupling28further includes a pair of first engaging projections36provided on a first side of the annular body35, and a pair of second engaging projections37provided on a second side of the annular body35. The first engaging projections36of the second Oldham coupling28are slidably engaged in a pair of first guiding grooves38provided on the support frame7, the first guiding grooves38being offset and extending parallel to the second displacement direction D2. The second engaging projections37of the second Oldham coupling28are slidably engaged in a pair of second guiding grooves39provided on the end plate14of the orbiting scroll member11, the second guiding grooves39being offset and extending parallel to the first displacement direction D1, i.e. perpendicularly to the second displacement direction D2. According to the embodiment of the invention shown inFIG. 2, the first and second engaging projections36,37extend respectively perpendicularly from the first and second sides of the annular body35.

As shown inFIGS. 3ato3d, the first and second Oldham couplings27,28are configured such that, in operation, the resulting center of gravity CGRof the first and second Oldham couplings27,28is moving along a circular trajectory whose center is located on the rotation axis A of the drive shaft24.

Further, as shown inFIGS. 3band3c, the first and second Oldham couplings27,28are configured such that the middle-stroke positions of the centers of gravity CG1, CG2of the first and second Oldham couplings27,28are located on the rotation axis A of the drive shaft24. The stroke length S1of the first Oldham coupling27along the first displacement direction D1may be substantially equal to the stroke length S2of the second Oldham coupling28along the second displacement direction D2.

The scroll refrigeration compressor2further comprises a rotating counterweight41attached to the drive shaft24and intended to balance on the one hand the total mass of the first and second Oldham couplings27,28, and on the other hand the mass of the orbiting scroll member11. The center of gravity of the counterweight41is substantially diametrically opposed to the resulting center of gravity of the first and second Oldham couplings27,28and of the orbiting scroll member11with respect to the rotation axis A of the drive shaft24.

FIGS. 4 to 6show a scroll refrigeration compressor2according to a second embodiment of the invention which differs from the one disclosed inFIGS. 1 and 2essentially in that the support frame7is replaced with a second fixed scroll member42comprising an end plate43fixed for example to the end plate12of the fixed scroll member9, and a spiral wrap44projecting from the end plate43towards the fixed scroll member9, and in that the orbiting scroll arrangement10further includes a second orbiting scroll member46. The orbiting scroll member46includes a spiral wrap47projecting from the end plate14towards the fixed scroll member42, the spiral wrap47of the orbiting scroll member46meshing with the spiral wrap44of the fixed scroll member42to form a plurality of compression chambers48between them.

Thus, according to the second embodiment, the spiral wraps15,47are provided on opposing faces of the end plate14of the orbiting scroll member11. However, according to another embodiment of the invention, the orbiting scroll member46may include a separate end plate secured to the end plate14of the orbiting scroll member11.

Further according to the second embodiment, the second Oldham coupling28is disposed between the end plate14of the orbiting scroll member11and the end plate43of the fixed scroll member42, and around the spiral wraps44,47. Furthermore the first engaging projections36of the second Oldham coupling28are slidably engaged in a pair of guiding grooves provided on the end plate43of the fixed scroll member42.

Of course, the invention is not restricted to the embodiments described above by way of non-limiting examples, but on the contrary it encompasses all embodiments thereof.