Floating Frame Mounting System and Method for a Refrigerator

FIG. 1 is a perspective view of a refrigerator cut away to illustrate the location of the mounting system of the present invention;

FIG. 2 is a perspective view of a prior art compressor housing mounting system for a refrigerator;

FIG. 3 is a spring mass diagram for the mounting system of the present invention;

FIG. 4 is a graph illustrating the transmissibility of a spring mass system as a function of frequency for three values of .beta.;

FIG. 5 is a perspective view of a first embodiment of the mounting system of the present invention;

FIG. 6a is a diagram illustrating a rear view of the mounting system of FIG. 5;

FIG. 6b is a diagram illustrating a side view of the mounting system of FIG. 5;

FIG. 7 is a perspective view of a second embodiment of the mounting system of the present invention;

FIG. 8a is a diagram illustrating a rear view of the mounting system of FIG. 7;

FIG. 8b is a diagram illustrating a side view of the mounting system of FIG. 7;

FIG. 9 is a graph illustrating the noise produced by a refrigerator having the compressor mounting system shown in FIG. 2; and

FIG. 10 is a graph illustrating the noise produced by a refrigerator having the compressor mounting system shown in FIG. 5.

A refrigerator 30, as shown in FIG. 1, constructed in accordance with the principles of the present invention includes a refrigerator frame or shell 32, a reciprocating compressor resiliently mounted by means of metal springs in a compressor housing 34, a condenser coil 36 and a mounting system, generally designated 38. As shown in greater detail in FIG. 5, the compressor housing 34 and condenser 36 are rigidly secured to the mounting system 38 which is, in turn, resiliently mounted on a front cross rail 40 and on a rear cross rail 42. The front and rear cross rails 40 and 42 are rigidly secured to the respective front and back of the refrigerator frame 32. As will be seen from the following discussion of FIGS. 3 and 4, by rigidly securing the compressor housing 34 to the mounting system 38 that also supports the condenser 36, and by further resiliently securing the mounting system 38 to the refrigerator frame 32, the amount of vibration transmitted from the compressor contained within the housing 34 to the refrigerator frame 32 is substantially less than the amount of vibration transmitted to the refrigerator frame for the prior art mounting system depicted in FIG. 2.

The compressor mounting system of the present invention shown in FIGS. 1, 5 and 7 has multiple degrees of freedom. The compressor mounting system may be modeled as having two degrees of freedom as shown in FIG. 3 wherein the resilient compressor mounting within the housing 34 provides one degree of freedom and the apparatus that resiliently secures the mounting system 38 to the frame of the refrigerator provides a second degree of freedom.

More particularly, FIG. 3 is a spring mass diagram for a compressor mounting system having two degrees of freedom with a first mass, M1 and a second mass, M2. In both the systems of the prior art shown in FIG. 2 and of the present invention illustrated in FIGS. 1, 5 and 7, M1 represents the mass of the refrigerator's compressor. The constant K1 represents the spring constant associated with the metal springs (not shown) which resiliently mount the compressor in its housing, housing 10 for the prior art and housing 34 for the system of the present invention. For the prior art system shown in FIG. 2, the mass M2 represents the mass of the compressor housing 10 whereas the constant K2 represents the spring constant associated with the rubber isolators 11-13 which resiliently secure the compressor housing 10 to the support rails 14 and 16 of the prior art mounting system. For the mounting system of the present invention illustrated in FIGS. 1, 5 and 7, the mass M2 represents the effective mass of the compressor, i.e., the sum of the masses of the compressor housing 34, the condenser 36 and the mounting system 38, whereas the constant K2 represents the spring constant associated with the apparatus that resiliently secures the mounting system 38 to the frame of the refrigerator 32 as discussed in detail below with reference to FIGS. 5 and 7. A ratio, .beta., equal to the ratio of M2 to M1, is much greater for the system of the present invention shown in FIGS. 1, 5 and 7 than it is for the prior art system shown in FIG. 2 since the effective mass of the compressor housing M2 for the system of the present invention is much greater than that of the prior art.

FIG. 4 illustrates the vibration transmissibility of a system with two degrees of freedom as a function of the frequency ratio of the system for various values of the mass ratio, .beta., wherein the frequency ratio represents the ratio of the frequency of the driven system to the natural frequency of the system. As is seen in FIG. 4, at the frequency ratio of interest, 13.4, the transmission of vibration from the excitation of the mass M1 to the frame resiliently supporting the mass M2 decreases as the mass ratio .beta. increases from 0.1 to 1.6. Therefore, by increasing the effective mass of the compressor housing M2 to increase the mass ratio .beta., the system of the present invention decreases the amount of vibration transmitted from the compressor to the refrigerator frame 32 and thus decreases the amount of noise generated thereby.

The mounting system 38 of the present invention, as shown in greater detail in FIGS. 5, 6A and 6B includes a pair of support rails 50 and 52 to which the compressor housing 34 is rigidly secured. The condenser 36 is also mounted across the support rails 50 and 52 and rigidly secured thereto. Rubber isolators, such as rubber grommets 56, 57, 58 and 59 are disposed between respective ends 60, 61, 62 and 63 of the support rails 50 and 52 and the cross rails 40, 42 to resiliently mount the support rails 50 and 52 to the cross rails 40 and 42 of the refrigerator frame 32. The ends 60-63 of the support rails 50 and 52 and the rubber grommets 56-59 are secured to the cross rails 42 and 40 by respective bolts 64, 65, 66 and 67 extending through apertures in the ends 60-63, grommets 56-59 and cross rails 42 and 40. Because the compressor housing 34 and condenser 36 are rigidly secured to the support rails 50 and 52 of the mounting system 38, and the mounting system 38 is resiliently secured to the cross rails 40 and 42 of the refrigerator frame 32, the effective mass of the compressor housing M2, is equal to the sum of the masses of the compressor housing 34, condenser 36 and support rails 50 and 52.

The overall noise produced by a refrigerator employing the compressor mounting system shown in FIGS. 5, 6A and 6B is illustrated in FIG. 10. At the frequency of interest, 63 Hz, which represents the running speed of the compressor, the amount of radiated noise produced by a refrigerator having the mounting system of FIGS. 5, 6A and 6B is approximately 10 db below the amount of noise produced by a refrigerator having the prior art mounting system shown in FIG. 2.

As shown in FIGS. 7, 8A and 8B, the second embodiment of the mounting system 38 includes the support rails 50 and 52 to which the compressor housing 34 is rigidly secured by means of bolts 53-55 and to which the condenser 36 is also rigidly secured. In this embodiment, the mounting system 38 also includes a rear cross rail 82 to which ends 60 and 62 of the respective support rails 50 and 52 are rigidly secured by spot welds 70 and 72 or the like. The ends 61 and 63 of the support rails 50 and 52 are resiliently secured to the cross rail 40 of the refrigerator frame 32 by grommets 57 and 59 as discussed above with reference to FIG. 5. A pair of rubber grommets 84 and 86 are disposed between the cross rail 82 of the mounting system of FIGS. 7, 8a and 8b and the refrigerator frame 32 to resiliently mount the cross rail 82 on the refrigerator frame 32. Because the cross rail 82 in FIGS. 7, 8a and 8b is rigidly secured to the support rails 50 and 52 to which the compressor housing 34 and condenser 36 are rigidly secured, the effective mass of the compressor housing M2 is equal to the sum of the masses of the compressor housing 34, the condenser 36, the support rails 50 and 52 and the cross rail 82 so as to further increase the mass ratio .beta. and to substantially reduce the transmission of vibration from the compressor resiliently mounted in the housing 34 to the frame 32 of the refrigerator 10. Tests of this embodiment (FIGS. 7, 8A and 8B) have also shown a 10 db reduction in radiated noise as compared with a refrigerator having the mounting system shown in FIG. 2 at the frequency associated with the compressor running speed.

In still another embodiment of the present invention, the support rails 50 and 52 may be rigidly secured to the cross rail 40 as well as to the cross rail 82 so that the grommets 57 and 59 shown in FIG. 7 would be replaced by spot welds or the like. Grommets 90 and 92 would then be used to resiliently secure the cross rail 40 to the frame 32 of the refrigerator 30. In this embodiment the effective mass of the compressor housing would include the compressor housing 34, the condenser 36, the support rails 50 and 52 and the cross rails 40 and 82 to increase the mass ratio .beta. and to reduce the amount of noise generated by the transmission of vibration from the compressor to the refrigerator frame.

Many modifications and variations of the present invention are possible in light of the above teachings. Thus, it is to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as described hereinabove.