JP2014105588A - Hermetic type compressor, and refrigerator, freezer, and air conditioner using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce slide loss of a crank shaft to provide a more efficient hermetic type compressor.SOLUTION: In a crank shaft 40 connecting an electric element 20 and a compression element 10, an outer surface of the crank shaft 40 having a main shaft part 40a fixed to a rotor 22 of an electric element 20 and an eccentric shaft part 40c eccentrically provided with respect to the main shaft part 40a is formed with cutouts 61, 62, 63 each having cross section asymmetric with respect to a rotational direction of the crank shaft 40.

Description

  The present invention relates to a hermetic compressor, and in particular, hermetic compression suitable for use in refrigerators, freezers, refrigerator-freezers, refrigerated showcases, refrigerated showcases, etc. Related to the machine.

  In recent years, hermetic compressors used in refrigeration equipment, refrigeration equipment, and air conditioning equipment as described above have been required to be highly efficient in order to reduce power consumption, and at the same time, reduced noise and improved reliability. Is also desired.

  Patent Document 1 describes a hermetic compressor in which a ball bearing is adopted as a bearing that supports a main shaft as an example of a conventional hermetic compressor.

  The hermetic compressor described in Patent Document 1 will be described with reference to FIGS. 9 and 10. FIG. 9 is a longitudinal sectional view of the hermetic compressor described in Patent Document 1, and FIG. 10 is an enlarged view of the vicinity of the ball bearing shown in FIG.

  As shown in FIG. 9, the hermetic container 201 accommodates an electric element 204 having a stator 202 and a rotor 203 and a compression element 205 driven by the electric element 204. A lubricating oil 206 is stored at the bottom of the sealed container 201. The shaft 210 has a main shaft portion 211 fixed to the rotor 203 and an eccentric shaft portion 212 provided eccentric to the main shaft portion 211, and the main shaft portion 211 is rotatably supported by the main bearing 220. Yes.

  A main bearing 220 that supports the main shaft portion 211 is fixed to a cylinder block 214 that constitutes the compression element 205. A substantially cylindrical cylinder chamber 216 is provided in the cylinder block 214, and a piston 226 is accommodated in the cylinder chamber 216 so as to reciprocate.

  The eccentric shaft portion 212 and the piston 226 are connected via a connecting means 227. When the shaft 210 is rotationally driven by the electric element 204, the rotational motion of the eccentric shaft portion 212 is converted into linear motion by the connecting means 227, and the piston 226 is reciprocated in the cylinder chamber 216. By the reciprocation of the piston 226, the refrigerant gas is sucked into the cylinder chamber 216, compressed and discharged.

  As shown in FIG. 10, ball bearings 240 and 241 are mounted near the upper and lower ends of the main bearing 220, respectively, and the main shaft portion 211 (shaft 210) is rotatably supported by these ball bearings 240 and 241. ing.

  According to Patent Document 1, sliding loss is reduced by using ball bearings 240 and 241 as the main bearing, and high efficiency of the compressor is realized. Patent Document 1 also describes that the press-fit assembly of the ball bearings 240 and 241 is facilitated by making the diameter of the ball bearing 241 on the eccentric shaft side larger than the diameter of the other ball bearings 240. Yes.

  Further, a bearing device described in Patent Document 2 is known as a method of supporting a rotating shaft with a small sliding loss, instead of a ball bearing. The bearing device described in Patent Document 2 will be described with reference to FIG. FIG. 11 is a cross-sectional view of the bearing device described in Patent Document 2.

  In the bearing device described in Patent Document 2, a rotary shaft 301 is rotatably supported inside a cylindrical bearing member 302. A fluid film 305 made of a lubricating fluid is formed between the cylindrical bearing surfaces 303 and 304 of the bearing member 302 and the rotating shaft 301 facing each other. A large number of spiral grooves 306 are formed on the outer peripheral surface of the rotating shaft 301 constituting one cylindrical bearing surface 303. These spiral grooves 306 are formed symmetrically on both sides of the cylindrical bearing surface 303 as a boundary. More specifically, the spiral groove 306 is formed in line symmetry with respect to a straight line AA passing through the center of the cylindrical bearing surface 303 in the axial direction. In addition, circumferential grooves 307 having a rectangular cross section are formed on both outer sides in the axial direction of the cylindrical bearing surface 303. In each of the axial center of the cylindrical bearing surface 303 and the circumferential groove 307, radial passages 308 extending radially from the axis of the rotating shaft 301 toward the outer peripheral surface are opened. Although not shown, each radial passage 308 communicates with a common axial passage that passes through the axis of the rotating shaft 301. The radial passage 308 and the axial passage constitute a high-pressure supply passage that reaches the circumferential groove 307 from the center of the spiral groove 306, and the radial passage 308 that opens in the circumferential groove 307 has an orifice as a fluid resistance. It is composed.

  In Patent Document 2, when the rotating shaft 301 is rotated, a pumping pressure is generated by the spiral groove 306, and the fluid pressure near the center in the axial direction of the cylindrical bearing surface 303 is increased. The pumping pressure causes the rotating shaft 301 to move over the entire circumference. It is described that the pressure is evenly applied and the rotational torque can be reduced.

JP 63-5186 A JP-A 63-275812

  If a ball bearing is used for the bearing as in the hermetic compressor described in Patent Document 1, the cost increases. Further, the ball bearing may be damaged when subjected to an impact load.

  Further, in the bearing device described in Patent Document 2, when a lubricating oil having a relatively low speed and a low viscosity is used, the pumping pressure by the spiral groove cannot be sufficiently obtained, and the sliding loss of the bearing may increase. There is.

  An object of the present invention is to reduce the sliding loss of the crankshaft and to realize further improvement in efficiency of the hermetic compressor.

  In the hermetic compressor of the present invention, a notch having an asymmetric cross-sectional shape with respect to the rotation direction of the crankshaft is formed on the outer peripheral surface of the crankshaft connecting the electric element and the compression element.

  In one aspect of the present invention, the plurality of notches are arranged along the circumferential direction of the crankshaft.

  In another aspect of the present invention, a bearing having a pressure receiving surface facing the outer peripheral surface of the crankshaft is provided, and a gap between the bottom surface of the notch and the pressure receiving surface is opposite to the rotation direction of the crankshaft. It becomes narrower in the direction.

  In another aspect of the present invention, the crankshaft has a main shaft portion supported by the bearing and an eccentric shaft portion provided eccentric to the main shaft portion, and at least on an outer peripheral surface of the main shaft portion. The notch is formed.

  In another aspect of the present invention, the main shaft portion includes two large diameter portions and a small diameter portion provided between the large diameter portions, and the pressure receiving surface of the bearing includes the large diameter portion and the large diameter portion. Opposite to the outer peripheral surface of the small diameter portion, the notch is formed in the outer peripheral surface of the large diameter portion, and one end of the notch opens in a gap between the outer peripheral surface of the small diameter portion and the pressure receiving surface. doing.

  In another aspect of the present invention, at least one outer peripheral surface of the two large-diameter portions has a first notch in which one end is opened in a gap between the outer peripheral surface of the small-diameter portion and the pressure-receiving surface. And a second notch that is not open in the gap between the outer peripheral surface of the small diameter portion and the pressure receiving surface.

  In another aspect of the present invention, the first notches and the second notches are alternately arranged along the circumferential direction of the main shaft portion.

  In another aspect of the present invention, the notch is partially formed on the outer peripheral surface of the two large diameter portions, and the position of the notch in one of the large diameter portions and the other large diameter. The position of the notch in the portion differs with respect to the rotation direction of the main shaft portion.

  The refrigeration / freezing / air-conditioning apparatus of the present invention has the hermetic compressor according to any one of the above aspects.

  According to the present invention, the sliding loss of the crankshaft is reduced, and further increase in efficiency of the hermetic compressor is realized.

1 is a longitudinal sectional view of a reciprocating hermetic compressor according to a first embodiment of the present invention. It is a partial expanded sectional view which shows the sliding part of a cylindrical part and a main-shaft part. It is typical sectional drawing which shows the shape and effect | action of a notch. It is a schematic diagram which shows an example of the formation method of a notch. It is a figure which shows the dynamic pressure distribution in the cross section orthogonal to the axial center of a crankshaft. It is a figure which shows the dynamic pressure distribution in the cross section parallel to the axial center of a crankshaft. It is a perspective view of the crankshaft used for the reciprocating type hermetic compressor which is the 2nd embodiment of the present invention. It is a perspective view of the crankshaft used for the reciprocating type hermetic compressor which is the 3rd embodiment of the present invention. It is a longitudinal cross-sectional view of the hermetic compressor described in Patent Document 1. FIG. 10 is a partially enlarged view of the vicinity of a ball bearing of the hermetic compressor shown in FIG. 9. It is a longitudinal cross-sectional view of the bearing apparatus described in Patent Document 2.

  Next, some embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol in drawing referred in the following description shows the same thing or an equivalent.

(First embodiment)
Here, a reciprocating hermetic compressor to which the present invention is applied will be described. As shown in FIG. 1, the hermetic compressor according to this embodiment includes a hermetic container 1. The hermetic container 1 accommodates a compression element 10, an electric element 20, a frame 30, and a crankshaft 40. Further, a suction pipe (not shown) and a discharge pipe 2 are connected to the side surface of the sealed container 1, respectively. One end of the suction pipe opens into the sealed container 1, the other end communicates with the evaporator of the refrigeration cycle, one end of the discharge pipe 2 connects to the compression element 10, and the other end communicates with the condenser of the refrigeration cycle. doing. By these, the inside of the airtight container 1 becomes a suction pressure during the operation of the compressor. That is, the compressor according to this embodiment is a low-pressure chamber type compressor. A lubricating oil 3 is stored at the bottom of the sealed container 1.

  The compression element 10 includes a cylinder 11 having a cylinder chamber 11a extending in the horizontal direction, a valve seat 12 and a cylinder head 13 disposed on one side of the cylinder 11, a piston 14 reciprocating in the cylinder chamber 11a, a crank And a coupling mechanism 15 that converts the rotational movement of the shaft 40 into the reciprocating movement of the piston 14. The cylinder 11 and the frame 30 are integrally formed castings.

  The electric element 20 includes a stator 21 composed of an armature core and windings, and a rotor 22 that is rotatably disposed inside the stator 21. The compression element 10 and the electric element 20 are arranged substantially vertically. The electric element 20 drives the compression element 10 via the crankshaft 40. The stator 21 is supported on the bottom of the sealed container 1 via a coil spring 23.

  The cylinder chamber 11 a constituting the compression element 10 is open on both sides in the horizontal direction, one side is closed by the piston 14, and the other side is closed by the valve seat 12 and the cylinder head 13. The valve seat 12 and the cylinder head 13 are fixed to the end surface of the cylinder 11 with bolts or the like. The valve seat 12 is provided with a suction hole, a suction valve, a discharge hole, and a discharge valve (all not shown). The inside of the cylinder head 13 is partitioned into a suction chamber and a discharge chamber.

  The crankshaft 40 is fixed to the rotor 22 of the electric element 20, and extends in the vertical direction from the main shaft portion 40a, the flange portion 40b provided at the upper end of the main shaft portion 40a, and extends from the flange portion 40b in the vertical direction. And an eccentric shaft portion 40c provided eccentric to the axis of the main shaft portion 40a. An oil pump 41 is attached to the lower end portion of the main shaft portion 40a.

  An oil supply hole (not shown) that constitutes a part of the oil supply path is formed inside the crankshaft 40. The oil supply hole passes through the main shaft portion 40a, the flange portion 40b, and the eccentric shaft portion 40c. Further, a plurality of branch holes extending in the radial direction of the crankshaft 40 extend from the oil supply holes, and each branch hole is opened at a predetermined position on the outer peripheral surface of the crankshaft. Lubricating oil pumped up by the oil pump 41 rises in the crankshaft 40 through the oil supply hole, and a part thereof is supplied to the outer peripheral surface of the crankshaft through the branch hole.

  The connection mechanism 15 in this embodiment is composed of a connecting rod. Therefore, in the following description, the connecting mechanism 15 is referred to as a “connecting rod 15”. The connecting rod 15 includes a ring portion 15a that is a large end portion, a sphere portion 15b that is a small end portion, and a connecting rod 15c that connects the ring portion 15a and the sphere portion 15b. The ring portion 15a, the connecting rod 15c, and the sphere portion 15b are integrally formed. The ring portion 15a is rotatably fitted to the eccentric shaft portion 40c of the crankshaft 40, and the sphere portion 15b is fitted to the ball seat 14a of the piston 14. It is coupled so that it can swing. The connecting rod 15c extends in a direction orthogonal to the eccentric shaft portion 40c of the crankshaft 40 extending in the vertical direction. That is, the connecting rod 15c extends in the horizontal direction.

  In the connecting rod 15, an oil supply hole that constitutes a part of the oil supply path is formed. The oil supply hole passes through the ring portion 15a, the connecting rod 15c, and the spherical body portion 15b, and is connected to the oil supply hole in the crankshaft 40 through a branch hole that is open on the outer peripheral surface of the eccentric shaft portion 40c of the crankshaft 40. Communicate.

  The frame 30 is placed and fixed on the stator 21 of the electric element 20. The frame 30 constitutes a bearing (main bearing) that rotatably supports the crankshaft 40. Specifically, as shown in FIG. 2, the frame 30 includes a cylindrical portion 31, and the main shaft portion 40 a of the crankshaft 40 is inserted into the cylindrical portion 31 and is rotatably supported. That is, the inner peripheral surface 31a of the cylindrical portion 31 of the frame 30 constitutes a slide bearing that supports the main shaft portion 40a in the radial direction. In other words, the radial load applied to the crankshaft 40 is supported by the inner peripheral surface 31 a of the cylindrical portion 31.

  Refer to FIG. 1 again. Large diameter portions 42 and 43 having a diameter of 18 mm are provided above and below the axial direction of the main shaft portion 40 a of the crankshaft 40, and a small diameter portion 44 having a diameter of 17.6 mm is provided between the two large diameter portions 42 and 43. It has been. For this reason, out of the outer peripheral surface of the main shaft portion 40a, the outer peripheral surfaces of the large diameter portions 42 and 43 mainly function as sliding surfaces supported by the inner peripheral surface 31a of the cylindrical portion 31, and the outer peripheral surface of the small diameter portion 44 is It functions exclusively as a flank. Therefore, in the following description, the inner peripheral surface 31a of the cylindrical portion 31 of the frame 30 is referred to as “pressure receiving surface 31a”, and the outer peripheral surfaces of the large diameter portions 42 and 43 of the main shaft portion 40a are referred to as “sliding surfaces” The outer peripheral surface of 44 is sometimes referred to as “flank 44a” to be distinguished. Further, the outer peripheral surface of the large-diameter portion 42 positioned below the main shaft portion 40a in the axial direction is called a “downward sliding surface 42a”, and the outer peripheral surface of the large-diameter portion 43 positioned upper in the axial direction is “upper-sliding”. Sometimes referred to as a surface 43a ". However, such a distinction is merely a distinction for convenience of explanation. The radial load is caused by the suction of refrigerant gas, the reaction force during compression, the dead weight of the crankshaft 40 and the rotor 22, the magnetic thrust of the electric element 20, and the like.

  As shown in FIG. 1, spiral grooves and fine cutouts are formed on the outer peripheral surface of the main shaft portion 40a. Specifically, a first spiral groove 51 is formed from the lower sliding surface 42a to the clearance surface 44a, and a second spiral groove 52 is formed from the clearance surface 44a to the upper sliding surface 43a. . On the other hand, the lower sliding surface 42a and the upper sliding surface 43a are formed with a plurality of notches 61, 62 extending along the axial center of the main shaft portion 40a at regular intervals along the circumferential direction.

  Here, as described above, the oil supply hole penetrating the crankshaft 40 communicates with the outer peripheral surface of the crankshaft through the plurality of branch holes. One end of the first spiral groove 51 communicates with the first branch hole opened in the lower sliding surface 42a, and the other end communicates with the second branch hole opened in the escape surface 44a. . Further, one end of the second spiral groove 52 communicates with a third branch hole opened in the flank 44a, and the other end communicates with a fourth branch hole opened in the upper sliding face 43a. ing.

  The lubricating oil supplied to the first spiral groove 51 through the first branch hole rises on the outer peripheral surface of the crankshaft along the first spiral groove 51 and returns to the oil supply hole from the second branch hole. . Further, the lubricating oil supplied to the second spiral groove 52 through the third branch hole rises on the outer peripheral surface of the crankshaft along the second spiral groove 52, and is supplied from the fourth branch hole to the oil supply hole. Return to. In this process, part of the lubricating oil is supplied to the lower sliding surface 42a, the flank surface 44a, and the clearance (bearing clearance) between the upper sliding surface 43a and the pressure receiving surface 31a.

  Next, the notch 61 formed in the lower sliding surface 42a and the notch 62 formed in the upper sliding surface 43a will be described. However, the shapes and dimensions of the notches 61 and 62 are the same or substantially the same. Accordingly, the details of the notches 61 and 62 will be described taking the notch 61 formed in the lower sliding surface 42a as an example.

  As shown in FIG. 1, the notch 61 is formed in an elongated shape along the axis of the main shaft portion 40a. That is, in the notch 61, the axial direction of the main shaft portion 40a is the longitudinal direction (length direction), and the rotation direction of the main shaft portion 40a is the short direction (width direction). As shown in FIG. 3, the notch 61 has a generally L-shaped cross-sectional shape as a whole by a flat bottom surface 61a and a side surface 61b rising from one side of the bottom surface 61a at a substantially right angle. In other words, the bottom surface 61a of the notch 61 includes a pair of long sides extending parallel to each other along the axis of the main shaft portion 40a, and the side surface 61b rises substantially vertically from one long side, The other long side is continuous with the downward sliding surface 42a. Therefore, the notch 61 has an asymmetric cross-sectional shape with respect to the rotation direction of the crankshaft 40 (main shaft portion 40a). That is, the notch 61 is asymmetric with respect to a plane (B cross section shown in FIG. 6) that passes through the bottom surface 61a and includes the axis of the main shaft portion 40a.

  The depth (d) of the notch 61 shown in FIG. 3 is 0.01 mm. That is, the height of the side surface 61b is 0.01 mm. The width (w) of the notch 61 is about 0.42 mm. In the present embodiment in which the diameters of the large-diameter portions 42 and 43 shown in FIG. 1 are each 18 mm, the notches 61 and 62 having the above-described dimensions are 20 at equal intervals on the lower sliding surface 42a and the upper sliding surface 43a, respectively. Is formed.

  The notches 61 and 62 can be formed by any method, but in the present embodiment, the notches 61 and 62 are formed by the method shown in FIGS. That is, the end mill 100 having a diameter of 6 mm is arranged in a direction in which its axis is perpendicular to the axis of the crankshaft 40, and then the notch 61 is moved by moving the endmill 100 in the direction of the axis of the crankshaft 40 while rotating the endmill 100. , 62 was formed. Therefore, as shown in FIG. 4 (c), corners R having a curvature radius of about 3 mm are attached to the ends of the notches 61 and 62, respectively.

  Reference is again made to FIG. As a result of the notch 61 having the cross-sectional shape as described above, the gap between the bottom surface 61a of the notch 61 and the pressure receiving surface 31a facing the notch 61 is not uniform with respect to the rotational direction of the main shaft portion 40a. Specifically, the notch 61 has a substantially L-shaped cross section, while the pressure receiving surface 31a is an arc surface. Therefore, the gap between the bottom surface 61a of the notch 61 and the pressure receiving surface 31a is gradually narrowed in the direction opposite to the rotation direction of the main shaft portion 40a (from the left side to the right side in FIG. 3). That is, the width gradually decreases as the distance from the side surface 61b of the notch 61 increases in the direction opposite to the rotation direction of the main shaft portion 40a. Also in this respect, the notches 61 and 62 are common. That is, although not shown, the gap between the bottom surface of the notch 62 and the pressure receiving surface 31a shown in FIG. 1 is gradually narrowed in the direction opposite to the rotation direction of the main shaft portion 40a.

  As shown in FIGS. 1 and 2, one end of each notch 61 formed in the lower sliding surface 42a reaches the boundary between the lower sliding surface 42a and the flank surface 44a. Further, as shown in FIG. 1, one end of each notch 62 formed on the upper sliding surface 43a reaches the boundary between the upper sliding surface 43a and the flank surface 44a. That is, one end of the notches 61 and 62 is opened in a gap between the flank surface 44a and the pressure receiving surface 31a. Therefore, the lubricating oil supplied to the gap between the relief surface 44a and the pressure receiving surface 31a via the spiral grooves 51 and 52 is filled not only in this gap but also in the notches 61 and 62. On the other hand, the other ends of the notches 61 and 62 are closed between the sliding surfaces 42a and 43a and the pressure receiving surface 31a. For example, as shown in FIG. 2, the other end of the notch 61 does not protrude outside the cylindrical portion 31 and is contained inside the cylindrical portion 31. That is, the other end of the notch 61 is closed between the lower sliding surface 42a and the pressure receiving surface 31a.

  So far, the notches 61 and 62 formed in the main shaft portion 40a of the crankshaft 40 have been described. However, as shown in FIG. 1, a similar notch 63 is also formed on the outer peripheral surface of the eccentric shaft portion 40 c of the crankshaft 40. But the structure of the notch 63 currently formed in the outer peripheral surface of the eccentric shaft part 40c is substantially the same as the notches 61 and 62 demonstrated so far. The notch 63 can also be formed by the method shown in FIG. Therefore, repeated description is omitted, and only differences from the notches 61 and 62 will be described below.

  The depth of the notch 63 formed on the outer peripheral surface of the eccentric shaft portion 40c is 0.01 mm, as with the notches 61 and 62 formed on the outer peripheral surface of the main shaft portion 40a. On the other hand, the diameter of the eccentric shaft portion 40c is 14 mm thinner than the main shaft portion 40a. Therefore, the width of the notch 63 formed on the outer peripheral surface of the eccentric shaft portion 40c is 0.37 mm, which is narrower than the notches 61 and 62 formed on the outer peripheral surface of the main shaft portion 40a. Further, twelve notches 63 having the above dimensions are formed on the outer peripheral surface of the eccentric shaft portion 40c at equal intervals along the circumferential direction.

  Here, lubricating oil is supplied to a gap (bearing gap) between the ring portion 15a of the connecting rod 15 and the eccentric shaft portion 40c of the crankshaft 40 through an oil supply hole formed in the crankshaft 40. It has become. That is, the inner peripheral surface of the ring portion 15 a functions as a pressure receiving surface similar to the inner peripheral surface 31 a of the cylindrical portion 31. Therefore, in the following description, when simply referred to as “pressure receiving surface” without reference numerals, it includes both the inner peripheral surface 31a of the cylindrical portion 31 and the inner peripheral surface of the ring portion 15a. The lubricating oil supplied to the gap between the ring portion 15 a and the eccentric shaft portion 40 c is filled not only in this gap but also in the notch 63. Note that one end (lower end) of the notch 63 is positioned inside the ring portion 15a, but the other end (upper end) protrudes outside the ring portion 15a. Therefore, a part of the lubricating oil filled in the notch 63 leaks from the upper end of the notch 63 and scatters due to the centrifugal force accompanying the rotation of the crankshaft 40, and lubricates between the piston 14 and the cylinder 11. .

  The basic operation of the hermetic compressor configured as described above will be described below.

  When the rotor 22 of the electric element 20 shown in FIG. 1 is rotated, the crankshaft 40 is rotated accordingly. Then, the eccentric rotational motion of the eccentric shaft portion 40c is converted into a linear motion by the connecting rod 15, and the piston 14 reciprocates in the cylinder chamber 11a. Thereby, the refrigerant gas is sucked into the cylinder chamber 11a through the cylinder head 13 and the valve seat 12, and is compressed in the cylinder chamber 11a. The compressed refrigerant is discharged through a discharge pipe 2 to a condenser outside the sealed container 1.

  On the other hand, with the rotation of the crankshaft 40, the lubricating oil 3 stored at the bottom of the sealed container 1 is pumped up by the oil pump 41 and introduced into the oil supply hole in the crankshaft 40. The lubricating oil introduced into the oil supply hole is supplied to each sliding portion through a predetermined oil supply path. These sliding portions include not only between the outer peripheral surface (sliding surface) of the main shaft portion 40a and the eccentric shaft portion 40c of the crankshaft 40 and the pressure receiving surface, but also between the spherical portion 15b and the ball seat 14a. Is also included.

  Next, the operation of the bearing accompanying the rotation of the crankshaft 40 will be described. 5 and 6 are diagrams showing the radial load load capacity of the bearing in this embodiment, that is, the cylindrical portion 31 shown in FIG. Specifically, FIG. 5 shows the dynamic pressure distribution in the cross section (cross section A) perpendicular to the axis when the bearing gap is set to 0.01 mm and the crankshaft 40 is rotated at 1000 revolutions per minute. Show. FIG. 6 shows a dynamic pressure distribution in a cross section (B cross section) parallel to the axis when the crankshaft 40 is rotated under the same conditions. In each of the drawings, as a comparative example, when a crankshaft having the same structure as the crankshaft 40 in the present embodiment is rotated under the same conditions except that the outer peripheral surface is not notched, The dynamic pressure distribution is also shown.

  The lubricating oil filled in the notches 61, 62, and 63 shown in FIG. 1 through the oil supply path as described above is rotated with the notches 61, 62, and 63 as the crankshaft 40 rotates. At this time, in the bearing of the present embodiment in which the notches 61, 62, 63 are asymmetric with respect to the rotation direction of the crankshaft 40, the lubricating oil in the gap between the bottom surface of the notches 61, 62, 63 and the pressure receiving surface is removed. It will be pushed from a wide part to a narrow part. This will be described more specifically by taking the notch 61 shown in FIG. 3B as an example. The gap between the bottom surface 61a of the notch 61 and the pressure receiving surface 31a shown in the drawing is gradually narrowed away from the side surface 61b of the notch 61 in the direction opposite to the rotation direction of the crankshaft 40 (main shaft portion 40a). . Therefore, when the crankshaft 40 rotates in the direction of the arrow in the figure, the lubricating oil in the gap is separated from a wide portion (region relatively close to the side surface 61b) to a narrow portion (relatively away from the side surface 61b). To the other area). As a result, a so-called pumping pressure is generated. As shown in FIG. 6, in the bearing in the present embodiment, a larger dynamic pressure than that in the comparative example is obtained in the entire region in the B cross section. Further, as shown in FIG. 5, the peak of the dynamic pressure distribution in the A cross section rises sharply compared to the comparative example. The steep rise of the dynamic pressure peak is that the notches 61, 62, 63 are asymmetric with respect to the rotation direction of the crankshaft 40, and therefore the gap between the bottom surface of each notch 61, 62, 63 and the pressure receiving surface. This is a unique effect obtained by the configuration of the present embodiment in which the lubricating oil is pushed from a wide part to a narrow part in the gap. Such a steep rise in the dynamic pressure peak has an effect of effectively preventing contact between the outer peripheral surface (sliding surface) of the crankshaft and the inner peripheral surface (pressure receiving surface) of the bearing. That is, the generation of noise and loss due to friction between the sliding surface and the pressure receiving surface is reduced, the efficiency of the compressor is improved, and the reliability is also improved.

(Second Embodiment)
Next, another example of the reciprocating hermetic compressor to which the present invention is applied will be described. However, the hermetic compressor according to the present embodiment has basically the same configuration as the hermetic compressor according to the first embodiment. Therefore, the description of the same configuration as the hermetic compressor according to the first embodiment is omitted, and only the difference will be described below.

  FIG. 7 is a perspective view of the crankshaft 40 used in the hermetic compressor according to the present embodiment. The illustrated crankshaft 40 is different from the crankshaft 40 shown in FIG. 1 or the like with respect to the arrangement of the notches 61 formed in the main shaft portion 40a. Specifically, in the crankshaft 40 shown in FIG. 7, a plurality of notches 61 on the lower sliding surface 42a are arranged in a staggered manner. More specifically, the notches 61 adjacent to each other in the circumferential direction are offset from each other in the axial direction. Further, the first notch 71a that is relatively close to the small diameter portion 44 communicates with the relief surface 44a, and the second notch 71b that is relatively spaced from the small diameter portion 44 is the relief surface 44a. Not communicating with

  The notches 71a communicating with the flank 44a and the notches 71b not communicating with the flank 44a are alternately arranged with respect to the rotation direction of the crankshaft 40, so that the dynamic pressure distribution in the rotation direction is mutually complemented, A more effective dynamic pressure distribution can be obtained.

(Third embodiment)
Next, still another example of a reciprocating hermetic compressor to which the present invention is applied will be described. However, the hermetic compressor according to the present embodiment has basically the same configuration as the hermetic compressor according to the first embodiment. Therefore, the description of the same configuration as the hermetic compressor according to the first embodiment is omitted, and only the difference will be described below.

  FIG. 8 is a perspective view of the crankshaft 40 used in the hermetic compressor according to the present embodiment. The illustrated crankshaft 40 is different from the crankshaft 40 shown in FIG. 1 and the like with respect to the arrangement of the notches 61 and 62 formed in the main shaft portion 40a. In the crankshaft 40 shown in FIG. 1 and the like, the notches 61 and 62 are uniformly formed over the entire circumference of the main shaft portion 40a. On the other hand, in the crankshaft 40 shown in FIG. 8, notches 61 and 62 are partially formed. Specifically, the notch 61 is formed only in a part in the circumferential direction of the outer peripheral surface (downward sliding surface 42a) of the large diameter portion 42. Further, a notch 62 is formed only in a part in the circumferential direction of the outer peripheral surface (upper sliding surface 43a) of the large diameter portion 43. Furthermore, the position of the notch 61 in the large diameter portion 42 and the position of the notch 62 in the large diameter portion 43 are different with respect to the rotation direction of the main shaft portion 40a. That is, the notch 61 and the notch 62 have different rotational phases.

  The notch 62 is formed 180 degrees opposite to the eccentric shaft portion 40c across the axis of the main shaft portion 40a, and the notch 61 is formed on the same side as the eccentric shaft portion 40c. The notch 63 is formed on the same side as the notch 62. As described above, the notches 61, 62, and 63 are partially arranged on the outer peripheral surface of the crankshaft, and by adjusting the position thereof, the effect is obtained at the timing when the largest load is received during one rotation of the crankshaft 40. Pumping pressure can be generated. Even when the notch is formed over the entire circumference of the crankshaft 40, the same effect can be obtained by partially varying the density of the notch.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, if the notch has an asymmetric cross-sectional shape with respect to the rotation direction of the crankshaft so that the gap between the bottom surface of the notch and the pressure receiving surface becomes narrower in the direction opposite to the rotation direction of the crankshaft. Of course, the bottom surface of the notch is not necessarily flat. For example, the bottom surface of the notch may be stepped. When the bottom surface of the notch is stepped, the gap between the bottom surface of the notch and the pressure receiving surface becomes narrower in steps, but even in this case, the same effect as described above can be obtained. Moreover, the dimension regarding the notch and the crankshaft shown in this specification is an example, and can be appropriately changed.

DESCRIPTION OF SYMBOLS 1 Airtight container 3 Lubricating oil 10 Compression element 20 Electric element 30 Frame 31 Cylindrical part 31a Pressure receiving surface (inner peripheral surface)
40 crankshaft 40a main shaft portion 40b flange portion 40c eccentric shaft portion 42 large diameter portion 42a lower sliding surface 43 large diameter portion 43a upper sliding surface 44 small diameter portion 44a flank surface 51 first spiral groove 52 second spiral groove 61a Bottom 61b Side

Claims (9)

  A hermetic compressor characterized in that a notch having a cross-sectional shape asymmetric with respect to the rotation direction of the crankshaft is formed on the outer peripheral surface of the crankshaft connecting the electric element and the compression element. The hermetic compressor according to claim 1, wherein
A hermetic compressor, wherein the plurality of notches are disposed along a circumferential direction of the crankshaft. The hermetic compressor according to claim 1 or 2,
A bearing having a pressure receiving surface facing the outer peripheral surface of the crankshaft;
A hermetic compressor, wherein a gap between a bottom surface of the notch and the pressure receiving surface is narrowed in a direction opposite to a rotation direction of the crankshaft. The hermetic compressor according to claim 3,
The crankshaft has a main shaft portion supported by the bearing, and an eccentric shaft portion provided eccentric to the main shaft portion,
The hermetic compressor, wherein the notch is formed at least on an outer peripheral surface of the main shaft portion. The hermetic compressor according to claim 4, wherein
The main shaft portion has two large diameter portions and a small diameter portion provided between these large diameter portions,
The pressure receiving surface of the bearing is opposed to the outer peripheral surface of the large diameter portion and the small diameter portion,
The notch is formed on the outer peripheral surface of the large-diameter portion, and one end of the notch is opened in a gap between the outer peripheral surface of the small-diameter portion and the pressure-receiving surface. Mold compressor. The hermetic compressor according to claim 5, wherein
At least one outer peripheral surface of the two large diameter portions has a first notch that opens at a gap between the outer peripheral surface of the small diameter portion and the pressure receiving surface, and one end of the small diameter portion. A hermetic compressor, wherein a second notch that is not opened in a gap between an outer peripheral surface and the pressure receiving surface is formed. The hermetic compressor according to claim 6, wherein
The hermetic compressor, wherein the first notches and the second notches are alternately arranged along a circumferential direction of the main shaft portion. The hermetic compressor according to claim 5, wherein
The notches are partially formed on the outer peripheral surfaces of the two large diameter portions,
The hermetic compressor, wherein a position of the notch in one of the large-diameter portions and a position of the notch in the other large-diameter portion are different with respect to the rotation direction of the main shaft portion.   A refrigerating apparatus, a refrigerating apparatus, or an air conditioner comprising the hermetic compressor according to any one of claims 1 to 8.

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