Hermetically sealed motor compressor

Abstract

A hermetically sealed motor compressor including a casing and a compressor body received therein and provided with a frame having a rim formed on the periphery, wherein there are formed notches in the upper part of the rim and there are provided springs, the bottom end of which is fitted into a socket in each notch and the upper end of which is fixed to a spring hanger so as to suspend the compressor body in the casing.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a hermetically sealed motor compressor having a compressor body elastically suspended in a hermetically sealed casing. With compressor of such type, it is desired that the frame supporting electrically driven members and compressor part received in the casing be elastically suspended therein.

Heretofore, the compressor body has been elastically suspended in a casing by integrally forming projecting holders on the periphery of the frame and stretching springs across the holders and the hangers provided in the casing. With such a compressor, the spring holders have to be disposed outside of the frame periphery due to requirements for construction, presenting great difficulties in rendering the compressor compact. Further with the conventional compressor, the spring hanger assumes an L-form, one arm of which is fixed to the inner wall of the sealed casing and the other arm of which extends inward of the casing and is perforated with a tapped hole. The spring is fitted to the spring hanger by being inserted into the tapped hole. This fitting method often causes any of the springs to fall off the tapped hole during compressor operation, resulting in the occurrence of noises or compressor failures. Said method has further drawbacks that the necessity of screwing the spring into the spring hanger when the compressor body is placed in the casing not only consumes a great deal of work but also requires the spring hanger to be bored with a tapped hole, unavoidably using a prominently extending horizontal arm. Accordingly, the fitting of the compressor body into the casing results in the bulkiness of the casing and compressor body and further requires the frame of the compressor body to be provided with an allowance or hole for insertion of the spring hangers so as to facilitate the fitting or removal of the compressor body, thus making its construction extremely complicated.

SUMMARY OF THE INVENTION

In a compressor according to the present invention there is bored a screw hole n the upper part of each notch formed in the rim of a compressor frame and the compressor body is elastically suspended in the casing by causing the hangers fixed to the inner wall of the casing to be clasped by springs. An object of the present invention is to provide a hermetically sealed motor compressor which is made compact by forming a spring fitting socket in the upper part of each notch bored in the rim of the compressor frame.

Another object of the invention is to fit a spring into a cavity formed in the upper side or both upper and under sides of the extending arm of each spring hanger so as to prevent the spring from falling off said arm.

Still another object of the invention is to incline the extending arm by the pitch angle of the spring so as to fit it in an upright position, and, under normal condition, cause the compressor body to be only supported by the force vertically applied by the spring along its axis.

A further object of the invention is to fit the spring to the extending arm simply by causing said arm to be clasped by the spring, thereby facilitating the fitting of the compressor body into the casing.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view of a hermetically sealed motor compressor according to an embodiment of the present invention;

FIG. 2 is a plan view of the frame of FIG. 1;

FIG. 3 is a side view with part of FIG. 2 shown in section;

FIG. 4 is a plan view of a spring hanger;

FIG. 5 is an elevational view of the same;

FIG. 6 is an elevational view of the same to which there are fitted springs; and

FIG. 7 presents a spring hanger according to another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, numeral 1 represents a hermetically sealed casing which is formed by connecting upper and lower shells 1a and 1b with each other. A compressor body 2 comprises a cylinder 3, an electric motor 4, a scotch yoke 5 for converting the rotation of the electric motor 4 to a linear motion, a piston 6 made to slide back and forth through the cylinder by the scotch yoke 5 and a generally cylindrical frame 7 for suspending the electric motor 4 and rotatably supporting the shaft 8 of the electric motor 4.

The electric motor 4 consists of a rotor 9 through which the shaft 8 passes and a stator 10 fitted to the frame 7. As shown in FIGS. 2 and 3, the frame 7 assumes a generally cup-shaped form, and is provided at the center with a cylindrical bracket 7a projecting downward so as rotatably to support the shaft 8 of the electric motor 4, and on the outer periphery with a rim 7b. Between the bracket 7a and rim 7b is defined a cavity 7c, into which there are received the rotor 9 and stator 10 of the electric motor 4 concentrically disposed with the shaft 8.

At the upper part of the rim 7b of the frame 7 are formed three or more notches 12 spaced from each other at substantially equal peripheral intervals. The upper surfaces 12a of the rim which are defined by the bottoms of said notches 12 is made substantially plain (or flat), and preferably disposed in a horizontal plane including the gravitational center of the compressor body 2 or its neighborhood. The outside of the frame 7 and cavity 7c communicate with each other through the notches 12 to expel heat generated by the electric motor 4 to the outside of the frame 7, thereby preventing temperature rise therein. Those parts of the rim surface 12a where there are formed the notches 12 are each bored with a spring socket 13, with at least the center of said spring socket 13 disposed inside of the outer periphery of the rim 7b. Into each spring socket 13 is fitted the bottom end of a spring 11 having the same pitch.

As shown in FIG. 1, the spring hangers 15 are fitted to the upper part of the lower shell 1b to hold the springs 11, thereby causing the compressor body 2 to be elastically suspended in the casing 1 by means of the springs 11. Numeral 14 denotes a cylindrical member fitted to the bottom plate of the lower shell 1b. Into the cylindrical member 14 is inserted the lower part of the shaft 8, the outer wall of which abuts against the inner wall of said cylindrical member 14 when the compressor body 2 rocks sidewise. Accordingly, the cylindrical member 14 serves as a sort of stop means for preventing the excess oscillation of the compressor body 2.

The spring hangers 15 are, as shown in FIGS. 4 and 5, L-shaped members comprising of a fitting portion 15a and an arm portion 15b. The fitting portion 15a is fixed to the upper part of the inner wall of the lower shell 1b of the casing 1 by welding or other means. Each arm portion 15b extends inward of the casing 1 (FIG. 1), and an imaginary inscribed circle defined by the free end face of the arm portion 15b usually has a larger diameter than the outer diameter of the frame 7. The upper surface of the arm portion 15b is inclined by an angle .theta. corresponding to the pitch angle of the spring 11 with respect to a horizontal plane. In said upper surface is formed a semicircular spring engaging groove 16 by which the arm portion 15b is clasped between two adjacent coils of the spring 11 as illustrated in FIG. 6. The underside of the upper coil is fitted into said spring engaging groove 16, and the upper side of the lower coil is pressed against the underside of the arm portion 15b. Accordingly, the easy fitting of the spring 11 to the arm portion 15b facilitates the incorporation of the compressor body 2 in the casing 1, permitting the arbitrary selection of its fitted position therein. Further the tight fitting of the spring 11 into the spring engaging groove 16 prevents said spring 11 from coming off the arm portion 15b, thereby eliminating the occurrence of those noises or compressor failures which have heretofore originated with such event.

The spring 11 is vertically held by the spring hanger 15 and, under normal condition, the frame 7 is only suspended by a torsional force applied by the spring 11 along its longitudinal direction, offering the advantage of eliminating the possibility of any lateral force being applied to the compressor body.

According to the embodiment of FIGS. 4 to 6, the upper part of each notch 12 is perforated with a spring socket 13 into which the spring is fitted. Accordingly, it is unnecessary to provide the outer periphery of the rim 7 with a large projection to hold the springs 11 or set them in place by screwing as is the case with the prior art compressor. Even if such projection should be required, it would only have to extend just a little, so that the casing 1 could be reduced in radius at least by that extent.

As mentioned above, the spring 11 is fitted to the spring hanger 15 by clasping the armed portion 15b by means of the spring engaging groove 16 formed therein, so that said arm portion 15b has only to extend inward just a little. Accordingly, said arm portion 15b does not obstruct the insertion of the compressor body 2 into the casing 1 for assembly or its removal therefrom for repair, particularly eliminating the necessity, as in the conventional compressor, of providing the frame 7 with an allowance or hole to facilitate the insertion or removal of the compressor body 2 by causing said allowance to slide along the spring hangers or broadening the inner diameter of the casing 1.

As described above, the present invention can render the compressor body compact due to the use of the casing 1 of reduced size. Further, the compressor body 2 is maintained in a horizontal plane including its gravitational center or its neighborhood, so that if the compressor body shakes, the moment of inertia will decrease with respect to said gravitational center, minimizing the effect exerted on the compressor body 2 by its oscillation.

FIG. 7 presents a spring hanger 15 according to another embodiment. In this embodiment, there is formed a semicircular spring groove 117 also in the underside of an arm portion 115b corresponding to the arm portion 15b of the embodiment of FIGS. 4 to 6. Formation of the spring engaging grooves 116 and 117 in both the upper and under sides of the arm portion 115b ensures the firmer clasp of the arm portion 115b by the spring 11 than in the embodiment of FIGS. 4 to 6.

Claims

What we claim is:

1. A hermetically sealed motor compressor including:

a hermetically sealed casing;

a compressor body housed in said casing and comprising a generally cup-shaped frame having a generally circular rim extending downward therefrom, said frame being provided at the upper portion thereof with a plurality of substantially equally spaced notches for causing the interior of said frame to communicate with the outside thereof, the bottom of each of said notches constituting the horizontally flat upper surface of said rim;

a plurality of generally L-shaped one piece spring hangers equal in number to the number of said notches, each spring hanger comprising a fitting portion fixed to said casing and an arm portion extending inwardly of said casing from said fitting portion, said spring hangers being disposed in said casing at a substantially equal peripheral spacing and with the free ends of said arm portions jointly defining an inscribed circle having a diameter larger than the outside diameter of said frame;

a plurality of springs equal in number to the number of said notches, each spring having the lower end portion thereof fitted into a spring socket provided on the upper surface of the rim at the respective notch, and having the upper end portion thereof connected with the arm portion of the respective spring hanger by means of said free end of said arm portion being inserted between two adjacent coils of the upper end portion of the respective spring; and

a substantially semicircular spring-engaging groove provided on at least one of the upper and lower surfaces of the arm portion of said spring hangers to receive one of the coils of its respective spring.

2. The motor compressor according to claim 1 wherein said arm portions of the spring hangers are inclined to the same extent as the pitch angle of said spring with respect to a horizontal place so as to suspend said spring substantially vertically.

3. The motor compressor according to claim 2 wherein the arm portion of each of said spring hangers is provided on the upper surface thereof with a substantially semicircular spring-engaging groove for receiving the upper coil of said two adjacent coils of the respective spring.

4. The motor compressor according to claim 3 wherein the arm portion of each of said spring hangers is provided on the lower surface thereof with a substantially semicircular spring-engaging groove for receiving the lower coil of said two adjacent coils of the respective spring.

5. The motor compressor according to claim 1 wherein the upper surface of said rim defined by the bottom of said notch lies substantially in a horizontal place including the gravitational center of the compressor body.

6. The motor compressor according to claim 1 wherein said casing has upper and lower parts, the fitting portions of said spring hangers being fixed to the lower part of said casing.