Patent Application
20200158100
The invention concerns a refrigerant compressor with a preferably hermetically sealable compressor housing, an electric drive unit comprising a rotor and a stator, a crankshaft that is nonrotatably connected to the rotor and that has a longitudinal axis, and a piston-cylinder-unit driven by the crankshaft, wherein the electric drive unit is made as an external rotor motor and the rotor has a carrier element extending radially outward with respect to the longitudinal axis at least partially, and the carrier element is nonrotatably mounted on the crankshaft.
Refrigerant compressors, in particular hermetically encapsulated refrigerant compressors, have long been known and are used chiefly in cooling appliances such as refrigerators or chilled display cases. The refrigeration process per se has likewise long been known. A refrigerant is heated in an evaporator by absorption of energy from the space that is to be cooled and then superheated and, by means of the refrigerant compressor, pumped to a higher pressure level in a piston-cylinder-unit by a piston moving back and forth in a cylinder housing, where the refrigerant releases heat via a condenser and is transported back to the evaporator via an expansion valve, in which a reduction of pressure and cooling of the refrigerant takes place. The motion of the piston is implemented via a crank drive comprising a crankshaft that is driven by an electric drive unit.
The electric drive unit made as an external rotor motor comprises a stator, which as a rule is made of a bundle of laminations and wire windings and is situated radially inward with respect to the longitudinal axis, thus closer to the crankshaft. Moreover, the drive unit comprises a rotor, which is disposed outward with respect to the longitudinal axis and outwardly surrounds the stator at least partially. A carrier element here serves as a connection between the electromagnetic components of the rotor, for example permanent magnets that are distributed over the circumference and are connected to each other via a shading ring, and the crank drive, in particular the crankshaft. The carrier element is connected to the crank drive, in particular the crankshaft, in a form fit, friction fit or a positive lock fit, in order to drive the crank drive by the electromagnetic interaction between rotor and stator during operation. The carrier element as a rule is connected to an end section of the driveshaft that faces away from the piston-cylinder-unit and extends radially outward from the crankshaft with respect to the longitudinal axis. In other words, the carrier element is connected to a free section of the crankshaft that faces away from the piston-cylinder-unit, while most of the crankshaft is mounted in a bearing bushing. In this case, the carrier element usually grips the stator from below; in other words, the carrier element is disposed between the side of the stator turned toward the oil sump and the oil sump.
Usually, the drive unit is made either as an asynchronous motor, wherein the stator comprises a bundle of laminations and/or copper or aluminum wire windings and the rotor comprises a bundle of laminations and aluminum legs with aluminum shading rings, or is made as a synchronous motor, wherein the stator comprises a bundle of laminations and/or copper or aluminum wire windings and the rotor comprises a plurality of permanent magnets.
In order to lubricate the piston-cylinder-unit and the crank drive, in particular the crankshaft, during operation, there is a lubricant-conveying system, by means of which lubricant is transported from a lubricant sump building up in a bottom region of the compressor housing during operation in the direction of the piston-cylinder-unit during the operation of the refrigerant compressor.
The lubricant-conveying system is generally formed at least in part by the crankshaft, where the crankshaft has at least one axial drilling and/or one eccentric drilling at the end opposite the piston-cylinder-unit, preferably on an end face of the crankshaft, through which lubricant is transported in the direction of the piston-cylinder-unit because of the centrifugal force in the rotation in the crankshaft. In addition or alternatively thereto, the crankshaft often has a helical groove made on the circumferential surface in a central section, which transports the lubricant upward on the circumferential surface and is connected to the axial drilling and/or the eccentric drilling.
A disadvantage of the prior art can be seen in that the overall transport power of the lubricant-conveying system becomes reduced by the lubricant transport height that must be overcome, in particular when picking up the lubricant from the lubricant sump. Said reduction of the transport power results from the amount of lubricant that can be transported by a transport based on centrifugal force, which amount diminishes with increasing transport height.
Therefore, it is an aim of the current invention to overcome the disadvantages of the prior art and to propose a refrigerant compressor with a drive unit made as an external rotor motor, which enables an increased power for transport of lubricant from a lubricant pump with a preferably lower, or reduced, height of the compressor.
In order to feed lubricant into a drilling that runs parallel to a longitudinal axis of the crankshaft or at an angle to the longitudinal axis, preferably an eccentric drilling in the crankshaft disposed eccentrically with respect to the longitudinal axis, without the end of the crankshaft opposite the piston-cylinder-unit projecting far above the rotor and without the end of the crankshaft opposite the piston-cylinder-unit dipping into the lubricant sump, a sleeve-shaped lubricant receptacle is connected nonrotatably, not to the crankshaft itself, hut rather to the carrier element. By attaching the lubricant receptacle to the carrier element, the lubricant receptacle rotates together with the crankshaft in the operating state, since the carrier element is itself connected nonrotatably to the crankshaft.
In the operating state, the sleeve-shaped lubricant receptacle dips into the oil sump, whereupon lubricant can pass into the lubricant receptacle, for example, through a lubricant inlet hole. The lubricant receptacle is usually made of a metallic material or a plastic. Due to the sleeve shape of the lubricant receptacle, thus the formation of the lubricant receptacle as a hollow body in which the lubricant can be held, lubricant in the lubricant receptacle is forced by centrifugal force to the inner wall of the lubricant receptacle, whereupon the pressure rises and the lubricant is transported toward the end of the crankshaft. Typically a lubricant parabola, or a parabola-shaped column of lubricant, forms within the lubricant receptacle.
By mounting the lubricant receptacle on the carrier element it is no longer necessary for the crankshaft to project beyond the carrier element in order to be able to attach the projecting section of the lubricant receptacle. The lubricant transport height can be reduced by this step, which leads to an increase of the transport power of the lubricant-conveying system. In other words, the transported amount of lubricant per unit of time is higher with the connection of the lubricant receptacle to the carrier element according to the invention than with a traditional connection of the lubricant receptacle to an end of the crankshaft that projects beyond the carrier element.
Through the higher transport power, a sufficient lubrication of the piston-cylinder-unit can be ensured at lower rotary speeds, so that the refrigerant compressor can be operated in an energy-optimized manner.
Thus, it is provided according to the invention that a sleeve-shaped lubricant receptacle for centrifugal transport of lubricant toward the piston-cylinder-unit from a lubricant sump formed in a bottom region of the compressor housing is provided on a side of the transport element facing away from the piston-cylinder-unit, where the sleeve-shaped lubricant receptacle is mounted nonrotatably on the carrier element.
“Nonrotatably connected” should be understood to mean that the lubricant receptacle rotates together with the crankshaft during the operation of the refrigerant compressor, and no relative movement between the lubricant receptacle and crankshaft arises. Said mechanical connection can be achieved on the one hand by the lubricant receptacle and carrier element being separate components and the lubricant receptacle being attached nonrotatably to the carrier element, thus in a form fit, friction fit, or positive lock fit. On the other hand, the nonrotatably connection can also be achieved if the carrier element and lubricant receptacle are made in one piece.
In one embodiment of the invention, it is provided that the carrier element has a central through-opening running coaxially to the longitudinal axis, wherein the sleeve-shaped lubricant receptacle is a separate component and a fastening portion of the sleeve-shaped lubricant receptacle is mounted on the carrier element in the region of the through-opening. Since the lubricant receptacle and carrier element are separate components, the sleeve-shaped lubricant receptacle as a rule also has a sleeve-shaped fastening portion, via which the lubricant receptacle is mounted nonrotatably on the carrier element, thus in a form fit, friction fit, or positive lock fit. The attachment of the fastening portion of the sleeve-shaped lubricant receptacle in the region of the through-opening enables effective transport of the lubricant from the lubricant receptacle into the drilling, which runs parallel to a longitudinal axis of the crankshaft or at an angle to the longitudinal axis, preferably the eccentric drilling in the crankshaft that is disposed eccentrically with respect to the longitudinal axis.
In order to improve the quality of the nonrotatable connection of the carrier element to the crankshaft, it is provided in another embodiment of the invention that the through-opening is made through a sleeve-shaped prolongation of the carrier element for the connection of the crankshaft. The crankshaft in this case can either be held in the through-opening formed by the sleeve-shaped prolongation of the carrier element or can have a recess, preferably a drilling, on the end turned away from the piston-cylinder-unit, in which the sleeve-shaped prolongation is held. The contact surface between crankshaft and carrier element is greatly increased by the sleeve-shaped prolongation, which is preferably made in one piece with the carrier element, without having to increase the wall thickness of the carrier element at the same time. A greater frictional force is achieved through the increased contact surface.
In another embodiment of the invention, the carrier element together with the sleeve-shaped prolongation can be produced in an especially inexpensive way in that the sleeve-shaped prolongation is formed from the carrier element by a forming operation. For example, the sleeve-shaped prolongation of the carrier element can be made as an extension of the carrier element made by a bending or deep drawing process.
A preferred embodiment of the refrigerant compressor according to the invention provides that the sleeve-shaped prolongation extends toward the side of the carrier element facing away from the piston-cylinder-unit, a section of the crankshaft is connected nonrotatably with the through-opening, and the fastening portion of the sleeve-shaped lubricant receptacle is attached to an outer surface, with respect to the longitudinal axis, of the sleeve-shaped prolongation. In assembled state, a section of the crankshaft, preferably the end section of the crankshaft facing away from the piston-cylinder-unit, is held and connected nonrotatably in the through-opening of the carrier element. Through this, the crankshaft is connected nonrotatably to the carrier element, for example in a force fit or friction fit. For example, the carrier element can be pressed or shrink-fit onto the crankshaft. Since the sleeve-shaped prolongation, which forms the preferably cylindrical through-opening, extends in the direction opposite to the piston-cylinder-unit, thus in other words toward the bottom region of the compressor housing, the sleeve-shaped prolongation is particularly suitable to hold the fastening portion of the lubricant receptacle. Because of the sleeve shape of the prolongation of the carrier element, the sleeve-shaped fastening portion of the lubricant receptacle can be attached to the sleeve-shaped prolongation of the carrier element in a simple way. The lubricant receptacle in this case is shifted outward toward the sleeve-shaped prolongation and is attached nonrotatably to the sleeve-shaped prolongation of the carrier element, preferably in a force tit, friction fit, or positive lock fit. For example, the fastening portion can be pressed or shrink-fit onto the sleeve-shaped prolongation.
To increase the surface pressure between the fastening portion of the lubricant receptacle, in particular an inner surface of the fastening portion, and the outer surface of the sleeve-shaped prolongation of the carrier element and thus to increase the holding force of the fastening portion on the carrier element, in another especially preferred embodiment of the invention, it is provided that a ring-shaped supporting element extending radially outward with respect to the longitudinal axis surrounds at least a section of the fastening portion of the sleeve-shaped lubricant receptacle. Due to the radial continuation of the supporting ring, in other words due to the wall strength of the ring-shaped supporting element, it has a high stiffness, which prevents deformation of the fastening portion and separation of the lubricant receptacle from the sleeve-shaped prolongation of the carrier element. A further effect of the ring-shaped supporting element is that the fit and holding force of the carrier element on the crankshaft are improved through the increased stiffness, or the increased surface pressure.
It is provided according to another preferred embodiment of the refrigerant compressor according to the invention that the fastening portion of the sleeve-shaped lubricant receptacle is formed from the ring-shaped supporting element at least in part. If the ring-shaped supporting element and the lubricant receptacle are made in one piece, thus the supporting element is made as a cross-sectional enlargement of the fastening portion, the assembly of the lubricant receptacle is simplified, since the supporting element need not be separately assembled. At the same time, the stiffness of the fastening portion is increased by the supporting element, so that the holding force of the lubricant receptacle on the carrier element is improved and separation of the lubricant receptacle from the carrier element is made more difficult or prevented.
In another preferred embodiment of the invention, it is provided that the ring-shaped supporting element is pressed or shrink-fit onto the fastening portion of the sleeve-shaped lubricant receptacle. The shrink-fit or pressed-on ring-shaped supporting element exerts a force directed radially inwardly in the direction of the longitudinal axis on an outer circumferential surface of the fastening portion of the lubricant receptacle, so that the clamping force or the resulting surface pressure is increased. In this way, both the nonrotatable, friction- or force-fit connection of the fastening portion onto the sleeve-shaped prolongation of the carrier element and also the nonrotatable friction- or force-fit connection of the carrier element to the crankshaft are ensured.
It is provided according to another especially preferred embodiment of the invention that a fastening portion of the sleeve-shaped lubricant receptacle extends parallel to the longitudinal axis and that the sleeve-shaped lubricant receptacle has a collar section extending radially outward with respect to the longitudinal axis, wherein the collar section preferably bears against the carrier element. The fastening portion of the lubricant receptacle extends parallel to the longitudinal axis, thus in other words forms a circular cylindrical sleeve, in order to enable simple assembly. The collar section keeps the lubricant receptacle from shifting in the axial direction, thus parallel to the longitudinal axis. Preferably, the shifting is prevented in that the collar section contacts the carrier element. At the same time, the collar section can also serve as a stop for the assembly of the lubricant receptacle.
An alternative embodiment of the invention provides that the sleeve-shaped prolongation extends to the side of the carrier element facing the piston-cylinder-unit, wherein the sleeve-shaped prolongation is connected nonrotatably to the crankshaft and the fastening portion of the sleeve-shaped lubricant receptacle is held nonrotatably in the through-opening formed by the sleeve-shaped prolongation. This embodiment is characterized by an especially compact construction, since the fastening portion of the lubricant receptacle is shifted not outward, but rather into the through-opening, preferably is pressed into it. In this way, the end face of the crankshaft facing away from the piston-cylinder-unit can have a recess, into which the sleeve shaped prolongation of the carrier element is pressed, in order to make the nonrotatable connection between the carrier element and the crankshaft.
As already noted, the one-piece embodiment of sleeve-Shaped lubricant receptacle and carrier element is a nonrotatable connection. This is why, in another alternative embodiment of the invention, it is provided that the sleeve-shaped lubricant receptacle and the carrier element are made in one piece, wherein the lubricant receptacle is formed from the carrier element by means of a forming operation, and the end of the crankshaft facing away from the piston-cylinder-unit is held nonrotatably in the sleeve-shaped lubricant receptacle. Lubricant receptacle and carrier element can in this case be made from a plate-shaped blank by means of a deep drawing process. In order to hold the end of the crankshaft nonrotatably in the lubricant receptacle, the carrier element can be pressed or shrink-fit onto the crankshaft. The assembly becomes further simplified because of the one-piece construction, since the separate assembly of the lubricant receptacle is no longer necessary.
The invention will now be explained in more detail by means of embodiment examples. The drawings are examples and are intended to present the ideas of the invention, but not to limit it in any way or even to render it conclusively.
Here:
The crankshaft 1 is part of a crank drive, which crank drive has a crankpin 26 eccentrically offset with respect to the longitudinal axis 2 and connected directly to the crankshaft 1. The piston-cylinder-unit 5 comprises a piston 25, which can be moved linearly back and forth in a cylinder housing 24, a connecting rod 23 connecting the crankpin 26 to the piston 25, a cylinder head system 27 comprising valves, and a suction muffler 28 connected to the cylinder head system 27.
In this embodiment example, the carrier housing 18 and the cylinder housing 24 are made in one piece, more precisely as a cast part. The carrier housing 18 has a plurality of continuations, via which the carrier housing 18 is mounted in the compressor housing 6 on spring elements 21, which are disposed in a bottom region 7 of the compressor housing 6. In alternative embodiments, the carrier housing 18 and cylinder housing 24 can be made in two pieces and connected to each other by connecting means.
The rotor 4 comprises, as shown in
In order to lubricate the bearing points of the crankshaft 1 in the bearing bushing 17 and the piston-cylinder-unit 5 in an operating state of the refrigerant compressor and to provide lubricant from a lubricant sump formed in the bottom region 7 of the compressor housing 6 in the operating state, the crankshaft 1 has, at the end opposite the piston-cylinder-unit 5, in other words at the lower end, an eccentric drilling running at an angle to the longitudinal axis 2, in other words running essentially axially, which is eccentrically disposed with respect to the longitudinal axis 2 in the radial direction. Lubricant that gets into the eccentric drilling is forced to the wall of the eccentric drilling because of the centrifugal force in the rotation of the crankshaft 1 and, because of the increased pressure, is transported in the direction of the piston-cylinder-unit 5. For example, the eccentric drilling can be made as a blind hole connected to the end facing the piston-cylinder-unit 5 via a radial drilling 20 with a helical groove 22 formed on the outer surface of the crankshaft 1 for transport of the lubricant.
In alternative embodiments, the eccentric drilling can also be disposed running parallel to the longitudinal axis 2 or instead of the eccentric drilling an axial drilling running coaxially with respect to the longitudinal axis 2 can be provided.
In order to bring lubricant from the lubricant sump into the eccentric drilling of the crankshaft 1 without needing a free end of the crankshaft 1 to dip into the lubricant sump, a sleeve-shaped lubricant receptacle 8, which is attached to the carrier element 12 and thus is nonrotatably connected to the crankshaft 1, is provided. The lower end of the crankshaft 1 here is pressed into the through-opening 13 of the prolongation 19 of the carrier element 12. In this embodiment example, the sleeve-shaped lubricant receptacle 8 and the carrier element 12 are made in two parts, where a fastening portion 9 of the lubricant receptacle 8 contacts the prolongation 19 of the carrier element 12.
As can easily be seen in
In order to improve, on the one hand, the connection of the carrier element 12 to the crankshaft 1 and, on the other hand, the connection of the fastening, portion 9 to the prolongation 19 and to increase the surface pressure between the carrier element 12 and the fastening portion 9 or between the fastening portion 9 and the crankshaft 1, a section of the fastening portion 9 is made as a ring-shaped supporting element 11. In this case, it is the end of the fastening portion facing the carrier element 12, where the ring-shaped supporting element 11 extends over about 80% of the fastening portion 9 looking in the axial direction. The ring-shaped supporting element 11 has a very large wall thickness by comparison with the rest of the lubricant receptacle 8, so that the fastening portion 9 has high stiffness in the region of the supporting element 11. A more reliable support of the fastening portion 9 on the prolongation 19 is ensured through this.
In alternative embodiments, the ring-shaped supporting element 11 can also be a part that is pressed or shrink-fit onto the fastening portion 9 and is a separate part from the lubricant receptacle 8. In other words, the supporting element 11 contacts an outer circumferential surface of the fastening portion 9 and exerts a force on the fastening portion 9 directed inwardly in the direction of the longitudinal axis 2. The surface pressure and the quality of the force fit or friction fit connection between the inner surface of the through-opening 13 and the crankshaft or between the inner surface of the fastening portion 9 and the outer surface of the prolongation 19 is increased. The supporting element 11 contacts a lower side of the carrier element 12 and overlaps about 80% of the prolongation 19.
It goes without saying that the ring-shaped supporting element 11 is indeed advantageous for the attachment of the lubricant receptacle 8 on the prolongation 19 but is not absolutely necessary. Alternatively, or in addition to the supporting element 11, the uppermost section of the lubricant receptacle 8 can also have a collar section, which extends outward in the radial direction at least in part.
Lubricant enters a receiving portion 10 of the lubricant receptacle 8 via a lubricant inlet hole. Since the lubricant receptacle 8 has a rotationally symmetric form with respect to the longitudinal axis 2 and is disposed coaxially with respect to the longitudinal axis 2, a lubricant parabola or a parabola-shaped column of lubricant is formed in the lubricant receptacle 8 by its rotation, passes into the eccentric drilling at the lower end of the crankshaft 1, and is transported farther there in the direction of the first radial drilling 20.
With increasing distance between the level of liquid in the lubricant sump and the radial drilling 20, which is also called the transport height, the transport power of the lubricant-conveying system decreases. An especially space-saving connection of the lubricant receptacle 8 to the crankshaft 1 is achieved by the attachment of the lubricant receptacle 8 to the sleeve-shaped prolongation 19 of the carrier element, so that the transport height can be reduced, and with this the transport power, thus the lubricant throughput per minute, can be increased. The increase of the transport power can be explained in that, because of the lower transport height, the wall thickness of the lubricant parabola in the region of the radial drilling 20 is greater and thus more lubricant reaches the helical groove 22.
It is provided in an alternative embodiment variation of the invention, which is not shown, that the lubricant receptacle 8 and carrier element 12 are made in one piece and the lubricant receptacle 8 is connected to the carrier element 12 or to the crankshaft 1 nonrotatably through this. The one-piece embodiment can be achieved, for example, by making the carrier element 12 together with the lubricant receptacle 8 from a plate-shaped blank in a deep drawing process. In this embodiment, the lower end of the crankshaft 1 is pressed into an upper section of the lubricant receptacle 8, or the lubricant receptacle 8 is shrink-fit onto the lower end of the crankshaft 1.
While the sleeve-shaped prolongation 19 of the carrier element 12 extends to the side facing away from the piston-cylinder-unit 5 in the first embodiment, in this embodiment example, the prolongation 19 extends in the direction of the piston-cylinder-unit 5 (compare with
In addition, a lubricant driver 16, which supports the formation of the lubricant parabola and increases the transport power of the oil transport device, can be disposed in the lubricant receptacle 8. Thus; a lubricant driver 16, which has at least one or more helical surfaces, which push the lubricant outward in the direction of the inner wall of the lubricant receptacle 8 or are Made for pushing the lubricant in the axial direction upward in the direction of the eccentric drilling of the crankshaft 1, is disposed in the lubricant receptacle 8 in each of the embodiment examples described previously. It is also conceivable for the one or more surfaces of the lubricant driver 16 to be made flat.
| Number | Date | Country | Kind |
|---|---|---|---|
| GM 50079/2017 | Apr 2017 | AT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/060877 | 4/27/2018 | WO | 00 |
