Abstract:
Provided is a simplified design for spring retainers in a hermetically enclosed refrigerant compressor. A hermetically enclosed refrigerant compressor includes a hermetically tight enclosure, and an electrical motor unit and a compressor supported relative to the enclosure by springs. The electrical motor unit and compressor include a first spring retainer and the enclosure includes a second spring retainer. The first and second spring retainers hold springs such that the electrical motor and compressor are supported relative to the enclosure. The first spring retainer is integrated with the electrical motor unit and the compressor.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Applicant hereby claims foreign priority benefits under U.S.C. §119 from German Patent Application No. 10 2007 038 443.4 filed on Aug. 16, 2007, the contents of which are incorporated by reference herein. 
     FIELD OF THE INVENTION 
     The invention concerns a hermetically enclosed refrigerant compressor arrangement having a hermetically tight enclosure, a unit comprising an electrical motor with stator and rotor and a compressor with cylinder head cover, and springs fixed on the unit via first spring retainers and on the enclosure via second spring retainers. 
     BACKGROUND OF THE INVENTION 
     Such a refrigerant compressor arrangement is known from DE 26 17 369 A1. The springs are made to be helical springs, which are located between the stator and the bottom of the enclosure. The stator-side first spring retainers are fitted on the heads of screws holding the stator core lamination together. The second spring retainers connected to the bottom of the enclosure are welded onto the enclosure. 
     U.S. Pat. No. 5,435,702 shows a compressor, in which the first spring retainers are screwed onto the stator by means of mounting fittings projecting laterally over the stator. The mounting fittings permit an expansion of the base surface, as the spring retainers can engage outside the outer edges of the stator. 
     DE 37 26 758 C2 shows a spring support of a compressor, in which the two kinds of spring retainers are made by means of deep-drawing of plate parts. 
     DE 37 19 436 A1 shows a hermetic refrigerant compressor, in which at least three support springs are provided, whose longitudinal axes are inclined in relation to the axis of the drive shaft, and which are located in different horizontal levels. Further to spring retainers on the stator, at least one spring retainer is formed in the suction arrangement of the compressor. 
     SUMMARY OF THE INVENTION 
     The invention is based on the task of simplifying the design of the spring mounting. 
     With a refrigerant compressor arrangement as mentioned in the introduction, this task is solved in that at least one of the elements cylinder head cover and end plate of the stator comprises at least one integrated first spring retainer. 
     Thus, it is possible, particularly in connection with small compressors, whose low refrigeration output only requires a small drive motor, to realise a relatively simply designed spring retainer, in which no additional threaded bores, screws, mounting fittings or the like are required. On the contrary, the spring retainers are integrated in the cylinder head cover and/or the end plate, that is, they are made in one piece with the cylinder head cover and/or the end plate of the stator, or they can be formed in these units already during manufacturing. During handling of the unit when assembling the compressor, no additional elements have to be handled to form the retainers for the springs. 
     Preferably, the bottom sides of the cylinder head cover and the end plate are located in the same horizontal level. When, in the following, the terms “horizontal” and “vertical” or “top” and “bottom” are used, they refer to the application related mounting position of the refrigerant compressor arrangement in a refrigeration appliance, for example a refrigerator or a freezer. When the bottom sides are located in the same horizontal level, a horizontal support of the unit is possible, so that a lateral force can only act upon the springs with little effect. 
     Preferably, all springs are located in the same horizontal level. Thus, not only the first spring retainers, but also the second spring retainers, are located in the same horizontal level. This enables a very stable operation of the arrangement. 
     Preferably, the stator has a stator core lamination, in which grooves are provided, the end plate engaging said grooves. The fact that the electrically isolating end plate engages the grooves means that it does not only isolate the stator core lamination from the electrical winding, which is located in the grooves. It also provides a form-fitting connection between the end plate and the stator core lamination, which prevents a lateral displacement of the end plate and the stator core lamination in relation to each other. Thus, the remaining forces used to connect the end plate and the stator core lamination to each other can be kept small, so that the end plate does not have to be dimensioned to be excessively strong. 
     Preferably, between the grooves the stator core lamination has webs, one front side of each web being covered by the end plate. Also this measure has two effects. Firstly, the end plate, which is made from an electrically isolating material, also isolates the coils from the stator core lamination in the area of the coil head. Secondly, the coils are used for further fixing the end plate to the stator core lamination. Also when the fixing forces acting upon the end plate from the winding are not excessively large, they contribute to the exact positioning of the end plate on the stator, so that an exact alignment between the spring or springs and the stator is ensured, also when the springs are not fixed directly on the stator core lamination, but on the end plate. 
     Preferably, the end plate is made as a plastic injection moulded part. With an injection moulded part it is possible, practically without additional costs, to integrate the first spring retainers. They are made in one piece with the end plate and are generated by using a corresponding injection mould. 
     Preferably, the end plate is made as a plastic injection molded part. With an injection molded part it is possible, practically without additional costs, to integrate the first spring retainers. They are made in one piece with the end plate and are generated by using a corresponding injection mold. 
     Preferably, the cylinder head cover is made as a pressure or injection molded part of aluminum. Also here, the first spring retainer can be formed on or in the part without problems, that is, additional working steps are not required to connect the first spring retainer to the cylinder head cover. 
     Preferably, the reinforcement brace is located in extension of a first spring retainer. In a manner of speaking, it can thus straight away adopt the forces acting upon the cylinder head cover from the spring. 
     Advantageously, a safety element is located on the inside of the enclosure facing away from the springs, said safety element engaging an opening of a safety ring located on the unit. The safety ring does not have to be circular. It is also possible to make a circular opening in an otherwise square ring, so that the safety ring has the shape of a plate with an opening. The interaction between the safety element and the safety ring then forms a securing device, that is, it is prevented that, for example during transport, the unit strikes against the enclosure, thus causing undue deformations. 
     Preferably, the safety element and/or the safety ring have a flexible coating. This coating can, for example, be made of a plastic or a rubber. The flexibility prevents the safety ring from hitting hardly on the safety element. 
     Preferably, the motor has a drive shaft, whose lower end is guided through an opening in a safety plate, which is fixed on the inside of the enclosure. Also this is an additional securing device. In relation to the enclosure, the motor can only move as far as the lower end of the drive shaft can move in the opening of the safety plate. 
     Preferably, at least one end of at least one spring has a retaining insert, with which it is fitted on its spring retainer. This gives the opportunity of providing the same spring retainers with springs of different shapes and sizes. This enables a cost-effective manufacturing, as one single kind of cylinder head cover and/or end plate can be used for a number of compressor units. 
     Preferably, the springs are located under the unit. Thus, they extend substantially in parallel to the drive shaft axis. This enables a very compact design of the refrigerant compressor arrangement. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following, a preferred embodiment is described in connection with the drawings, showing: 
         FIG. 1  a longitudinal section through a refrigerant compressor arrangement, 
         FIG. 2  a cross-section through the arrangement of  FIG. 1   
         FIG. 3  a perspective view of the lower end plate 
         FIG. 4  a stator of the motor 
         FIG. 5  a top view of the inside of the cylinder head cover. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a refrigerant compressor arrangement  1  with a hermetically tight, closed enclosure  2  comprising an upper part  3  and a lower part  4 . The upper part  3  has a flange  5 . The lower part  4  has a flange  6 . Along the flanges  5 ,  6  the upper part  3  and the lower part  4  are connected to each other, for example by means of welding. 
     The refrigerant compressor arrangement  1  has a unit  7  with an electric motor  8  and a compressor  9 . Via several springs  10 - 12 , the unit  7  is supported on the lower part  4  of the enclosure  2 , or rather on its bottom  13 . Here, the springs  10 - 12  are made as helical springs. 
     The motor  8  has a stator  14  and a rotor  15 . The rotor is unrotatably connected to a crank shaft  16 , for example by shrinking or pressing, and rotates inside a central opening of the stator  14 . The rotor  15  has a support part  17 , which can be made of metal and have permanent magnets  18  located on its radial outside. These magnets are fixed on the support part  17  by suitable means, for example adhesives or special clamps. 
     The stator  14  has a stator core lamination  19  having several pole teeth  20  on its radial inside, said pole teeth  20  being formed by webs and salient poles on the inside of the stator opening. In the grooves  19   a  ( FIG. 3 ) formed between the pole teeth  20 , windings  21  are located, each surrounding a web. 
     Between the stator core lamination  19  and the windings  21  is located an electrical isolation in the form of an upper end plate  22  and a lower end plate  23 . Each end plate  22 ,  23  completely covers an axial end face of the stator core lamination  19  and the axial surfaces of the pole teeth, except for the radial inner pole faces  24 . The two end plates  22 ,  23  touch each other in the grooves  19   a , or are at least very close to each other there. Thus, the two end plates  22 ,  23  form a complete electrical isolation between the windings  21  and the stator core lamination  19 . 
     The fact that the end plates  22 ,  23  are made to be three-dimensional causes that they do not only bear evenly on the front side of the stator core lamination  19 , but also engage the stator core lamination  19 , so that, in a manner of speaking, they are held at the stator core lamination  19  in a form-fitting manner. The stator core lamination  19  and the end plates  22 ,  23  have through bores  25 , through which fixing bolts can be guided. Firstly, these fixing bolts keep the stator core lamination  19  axially together. Secondly they serve the purpose of connecting the stator  14  of the motor  8  to a compressor block  26 , which will be described below. The fact that due to their three-dimensional design the end plates  22 ,  23  are to a great extent secured against a displacement in relation to the stator core lamination  19 , causes that the forces required for the tightening can be kept small, so that the mechanical strain on the end plates  22 ,  23  will not be excessively large. 
     The upper end plate  22  has electrical connections  27 , through which the motor  8  can be connected to an energy source. The connection is realised by means of cables, not shown in detail, which extend between the electrical connections  27  and a connection arrangement  28  inserted in a sealing manner in the enclosure. 
     The two end plates  22 ,  23  have circumferential projections  29 ,  30 , respectively. The circumferential projection  29  of the upper end plate  22  has several interruptions  31 , through which electrical cables or winding wires  32  can be guided. 
     The compressor block  26  has an extension  33  in the direction of the bottom  13 , the extension  33  extending through the stator  14  of the motor. Only windings  21  further extend over the extension  33  in the axial direction. The extension  33  forms a radial bearing  34 . At the upper side of the extension in the compressor block  26  is formed an axial bearing  35 , on which the crank shaft  16  bears with a plate  36 , the plate  36  carrying a crank pin  37  located eccentrically to the axis of the crank shaft  16 . At the end facing the upper part  3  the crank pin  37  has an opening  38  of an oil reservoir  39  that is supplied by an oil pump  41  via a pipe, which is not shown in detail, the pump  41  only being partly visible in  FIG. 1 . When the crank shaft rotates, oil from the oil reservoir  39  is sprayed inside the enclosure  2  via the opening  38 . 
     The stator  14  has a stator core lamination  19  having several pole teeth  20  on its radial inside, said pole teeth  20  being formed by webs  19   b  and salient poles on the inside of the stator opening. In the grooves  19   a  ( FIG. 3 ) formed between the pole teeth  20 , windings  21  are located, each surrounding a web. 
     The pressure chamber  46  is additionally bordered by a valve plate  47 , which is fitted on the compressor block  26 . In a manner known per se, the valve plate  47  has at least one inlet valve and at least one outlet valve to control the suction and the discharge process of refrigerant. On the side facing away from the compressor block  26  a cylinder head cover  48  bears on the valve plate  47 , the cylinder head cover  48  comprising suction and pressure chambers and a chamber for a muffler. 
     The lower end plate  23  comprises two first spring retainers  49 , on which the springs  11 ,  12  are mounted. The cylinder head cover  48  also comprises a first spring retainer  5   o , on which the spring  10  is mounted. “First spring retainers” are the spring retainers allocated to the unit  7 . 
     The lower end plate  23  is made as an injection moulded part of plastic. When making such an injection moulded part, it is possible without problems to make the first spring retainers  49  in one piece with the lower end plate  23  without causing additional costs. This saves a further mounting step, during which the first spring retainers  49  are connected to the motor  8 . 
     The cylinder head cover  48  is made of aluminum and is made in a pressure molding or injection molding process. Accordingly, it is also here possible to make the first spring retainer  50  in one piece with the cylinder head cover  48  without causing additional costs. The connection between the first spring retainer  50  and the cylinder head cover  48  is extremely stable. 
     However, not in all cases the cylinder head cover  48  has sufficient mechanical load capacity to adopt the forces corresponding to the weight force of the unit  7 . For this reason, the inside, that is, the side facing the valve plate  47 , of the cylinder head cover  48  is provided with a reinforcement brace  51 , which is located in extension of the spring  10 , so that forces from the spring  10  acting upon the cylinder head cover  48  can also be adopted by the reinforcement brace  51 . 
     The first spring retainers  49 ,  50  on the lower end plate  23  and the cylinder head cover  48  are in the same horizontal level, so that upwards the springs  10 - 12  also end in the same horizontal level. Also at the bottom  13  of the enclosure  2  the springs  10 - 12  are supported in the same horizontal level, so that they are practically only loaded by weight forces in the gravity direction. Thus, only during transport larger lateral deflections are a risk. During operation imbalances and the like may cause small lateral deflections of the springs  10 - 12 . 
     The inside of the upper part  3  is provided with a safety element  52 , which extends into an opening  53  in a safety ring  54 . The safety ring  54  has a deformable coating  55 , for example made of a plastic or a rubber. The safety element  52  is, for example, cylinder shaped. In this case, the opening  53  is circular. In relation to the enclosure  2 , the unit  7  can only move, until the safety ring  54  comes to rest on the safety element  52 . Thus, a deformation of the enclosure  2  is avoided. The coating  55  serves the purpose of keeping noises small, which could arise when the safety ring  54  comes to rest on the safety element  52 . Alternatively or additionally, of course also the safety element  52  can be provided with a corresponding damping coating. 
     At its lower end, the crank shaft  16  has an extension  56 , which extends through an opening  57  in a plate  58 , which is fixedly connected to the bottom  13  of the lower part  4 , for example by welding. Also this forms a securing device. The unit  7  can only move in relation to the lower part  4  until the extension  56  comes to rest on the plate  58 . 
     In the bottom  13  of the lower part  4  second spring retainers  59  are located, on which the springs  10 - 12  are mounted. The second spring retainers  59  comprise substantially cylindrical sections  60 , each extending through an opening  61  in the bottom  13 . This section  60  can be used for mounting the arrangement  1  on a base, for example a bottom plate of a refrigeration appliance. The section  60  is connected to the enclosure  2  in a hermetically tight manner. An elastic element serves as vibration suppression between the arrangement  1  and the base. At the lower end of the section  60  elastic tongues  63  are provided, with which the arrangement  1  can engage in openings of a bottom plate. 
     The lower end plate  23  is made as an injection molded part of plastic. When making such an injection molded part, it is possible without problems to make the first spring retainers  49  in one piece with the lower end plate  23  without causing additional costs. This saves a further mounting step, during which the first spring retainers  49  are connected to the motor  8 . 
     The cylinder head cover  48  is made of aluminum and is made in a pressure molding or injection molding process. Accordingly, it is also here possible to make the first spring retainer  50  in one piece with the cylinder head cover  48  without causing additional costs. The connection between the first spring retainer  50  and the cylinder head cover  48  is extremely stable. 
     The fact that the motor  8  is a permanent magnet energized synchronous motor with inner rotor, the rotor  15  having several permanent magnets  18  distributed on its outer circumferential face, permits the motor  8  to be made with a comparatively small height. This keeps the height of the arrangement  1  small. 
     Preferably, the bottom side  50   a  of the cylinder head cover  48  and the bottom side  23   a  of the end plate  23  are located in the same horizontal level. The first spring retainers  49 ,  50  on the lower end plate  23  and the cylinder head cover  48  are in the same horizontal level, so that upwards the springs  10 - 12  also end in the same horizontal level. Also at the bottom  13  of the enclosure  2  the springs  10 - 12  are supported in the same horizontal level, so that they are practically only loaded by weight forces in the gravity direction. Thus, only during transport larger lateral deflections are a risk. During operation imbalances and the like may cause small lateral deflections of the springs  10 - 12 . 
     The refrigerant compressor arrangement  1  works so that refrigerant gas is sucked into the enclosure  2  via a suction connector  66 . After compression in the pressure chamber  26  the refrigerant gas is discharged from the enclosure  2  through a pressure connector  67 . The control of the refrigerant gas takes place via the valve plate  47 . 
     While the present invention has been illustrated and described with respect to a particular embodiment thereof, it should be appreciated by those of ordinary skill in the art that various modifications to this invention may be made without departing from the spirit and scope of the present invention.