Hermetic compressor and refrigerator
View Patent ↗A hermetic compressor ( 100 ) includes an electric element ( 110 ), a compression element ( 112 ), and a hermetic container ( 102 ). The compression element includes a shaft ( 118 ), a cylinder block ( 124 ), a piston ( 136 ), a connection section ( 144 ), and an oil supply mechanism ( 130 ). The piston has a columnar seal section ( 160 ) in sliding contact with an inner peripheral face of the cylinder, two extension sections ( 162 ) that have circular arc faces each having the same radius as a radius of the seal section and extend from the seal section to the bottom dead center side in the axial direction with a circumferential gap therebetween, and a columnar capture section ( 164 ) that extends further toward the bottom dead center side than the extension section and has a smaller radius than the radius of the seal section.
1. A hermetic compressor comprising:
an electric element including a stator and a rotor that rotates relative to the stator;
a compression element driven by the electric element; and
a hermetic container that stores the electric element and the compression element, and accommodates lubricating oil, wherein
the compression element includes:
a shaft including a principal shaft to which the rotor is fixed and an eccentric shaft that is eccentric with respect to the principal shaft;
a cylinder block including a bearing that rotatably supports the principal shaft and a cylinder having an inner space;
a piston that reciprocates in the inner space; and
a connection section that couples the piston to the eccentric shaft, and the piston includes:
a seal section in sliding contact with an inner peripheral face of the cylinder;
two extension sections that have respective circular arc faces having the same radius as a radius of the seal section, are spaced in the circumferential direction, and extend from the seal section toward a crank shaft side in the axial direction; and
a capture section that further extends toward the crank shaft side than the extension sections, the capture section including a portion formed around the entire circumference of the piston and having a radius that is smaller than the radius of the seal section.
2. The hermetic compressor according to claim 1 , wherein
when the piston is located at a bottom dead center, at least a part of the capture section is exposed outside of the cylinder.
3. The hermetic compressor according to claim 1 , wherein
an axial length of each respective extension section of the two extension sections is within a range of one third to three times of a circumferential width of the respective extension section.
4. The hermetic compressor according to claim 3 , wherein
a length of each respective extension section of the two extension sections is equal to the width of the respective extension section.
5. The hermetic compressor according to claim 1 , further comprising a pin that connects the connection section to the piston, wherein
a length of each respective extension section of the two extension sections is within a range of one half to three over two of a diameter of the pin.
6. The hermetic compressor according to claim 1 , wherein
a length of each respective extension section of the two extension sections is larger than a length of the seal section, and
a central angle of a circular arc of each respective extension section of the two extension sections is within a range of 40 degrees to 90 degrees.
7. The hermetic compressor according to claim 1 , wherein
a direction in which the piston is pushed toward the inner peripheral face of the cylinder by the connection section when the piston moves toward a top dead center is a load side, and a direction opposite to the load side is a non-load side,
a width of one extension section of the two extension sections, which is located on the load side, is 1.2 times as much as a width of the other extension section located on the non-load side.
8. The hermetic compressor according to claim 1 , wherein
the piston further includes a lubricating oil lead-in section formed as an inclined face between each respective extension section of the two extension sections and the capture section.
9. The hermetic compressor according to claim 1 , wherein
a corner that connects a circumferential edge of each respective extension section of the two extension sections to an edge on the crank shaft side of the seal section is a rounded section curved like a circular arc.
10. The hermetic compressor according to claim 9 , wherein
a radius of the rounded section is within a range of 25% to 50% of a width of each respective extension section of the two extension sections.
11. The hermetic compressor according to claim 1 , wherein
the seal section is provided with an annular groove.
12. The hermetic compressor according to claim 1 , wherein
the piston is subjected to a surface treatment with a synthetic resin.
13. The hermetic compressor according to claim 1 , wherein
an axial length of a portion of the inner peripheral face of the cylinder, which is opposed to a respective extension section of the two extension sections, is larger than a remaining portion of the inner peripheral face.
14. The hermetic compressor according to claim 1 , wherein
at least a part of the inner peripheral face of the cylinder is tapered such that a radius on the crank shaft side is larger than a radius on a load side.
15. The hermetic compressor according to claim 1 , wherein
the electric element is driven by an inverter circuit with a plurality of rotation speeds.
16. A refrigerator comprising the hermetic compressor according to claim 1 .