JPS6160273B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reciprocating compressor in which a crank is provided on a rotating shaft and a piston is reciprocated via a connecting rod by eccentric rotation of the crank, and particularly relates to a damping device for abnormal internal pressure in a cylinder during compression. It is.

A conventional reciprocating compressor will be described with reference to FIGS. 1 and 2, taking a hermetic electric compressor as an example.

In Fig. 1, 1 is a crankshaft supported by an upper bearing 2 and a lower bearing 3 of a compressor, and an electric motor 4 mounted above.
has been set up. The compressor section forms a cylinder 6 integrally with the frame 5, and a cylinder head 7 and a head cover 8 are disposed on the end surface of the cylinder, and a suction chamber 9 and a discharge chamber 10 are formed within the cover 8. A suction pipe 11 whose upper end is open is connected to the chamber 9, and a discharge pipe 12 is connected to the discharge chamber 10. A piston 13 is housed inside the cylinder 6 and connected to the crankshaft 1 via a connecting rod 14. The electric compressor connected with the electric motor as described above is housed in a closed container 15.
16 indicates a gas return pipe.

FIG. 2 shows the crank portion of the crankshaft of the compressor. The crankshaft 1 has a crank 1a and a shaft 1b.
The shaft 1b is eccentrically mounted and fixed by a key 1c, and the rotation of the shaft 1b is transmitted to the crank 1a, which rotates eccentrically.

When the hermetic electric compressor described above is used as a compressor for a refrigeration system, the refrigerant gas flowing from the refrigerant circuit into the hermetic container 15 via the return pipe 16 is transferred from the suction pipe 11 to the suction chamber 9, It is sucked into the cylinder 6 through the suction valve (not shown) of the cylinder head 7, is then compressed by the reciprocating motion of the piston 13, and is then moved to the discharge valve (not shown) of the cylinder head 7.
is discharged into the discharge chamber 10 through the discharge pipe 12.
It is sent out of the aircraft via.

However, at the start of operation or due to temperature conditions, liquid is sucked into the cylinder 6, and when this liquid is compressed, the pressure inside the cylinder 6 near the top dead center of the piston 18 becomes higher than the maximum pressure during steady operation. Become.
However, in the above structure, since there is no buffer mechanism in the connection mechanism of the piston 13, connecting rod 14, crank 1a, and shaft 1b, the above abnormal internal pressure acts on the valve device and bearing section of the cylinder head 7, causing excessive pressure on the same section. The force applied may damage the valve gear and bearings.

The present invention was invented in view of the above, and it reduces the eccentricity of the crank and shaft when compressing liquid in a compressor, reduces the compression effect, avoids abnormally high cylinder internal pressure, and prevents the suction valve plate, bearing, etc. The purpose is to prevent accidents involving damage to parts.

The configuration of the present invention is characterized in that the crankshaft is provided with a mechanism that moves the crank in a direction that reduces the amount of eccentricity between the crank and the shaft when the cylinder internal pressure becomes abnormally high during liquid compression.

An embodiment of the present invention will be explained based on FIGS. 3 and 4.

In the figure, the shaft shape of the engagement portion between the shaft portion 21b of the crankshaft 21 and the crank 21a is a square 21.
b', and the shape of the engagement hole of the crank 21a is a rectangle 2 whose only eccentric direction is longer than the square 21b' of the shaft part.
1a', and the square 21b' portion of the shaft is slidably inserted into this engagement hole, that is, the eccentricity between the crank 21a and the shaft 21b can be changed. Reference numeral 22 denotes a spring, which positions the crank 21a so that the amount of eccentricity is maximum, and is inserted into a space created on the left side of the rectangular 21b' portion in the figure. The crank 21a is compressed and inserted with an initial force greater than the maximum load acting on the crank 21a, and the eccentricity of the crank 21a is maintained by a spring force greater than the maximum load. 23 is a holding plate that prevents the crank 21a from moving in the axial direction;
Provided on both end faces of part b'. Since the other parts are the same as those in FIG. 1, illustration and explanation will be omitted.

In the above structure, when liquid is sucked into the cylinder and becomes compressed, the pressure inside the cylinder near the top dead center of the piston becomes higher than the maximum pressure during steady operation, and this internal pressure 21a, the load is greater than the initial force of the spring 22, and the crank 21a presses the spring 22 to move in a direction that reduces the amount of eccentricity, reducing the compression effect and preventing the internal pressure of the cylinder from becoming abnormally high. Make it.

As described above, according to the present invention, it is possible to avoid abnormally high pressure inside the cylinder during liquid compression and prevent damage to the valve device, bearing, etc. of the cylinder head.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of a conventional hermetic compressor, Figure 2
1, FIG. 3 is a vertical sectional view of a main part showing an embodiment of the present invention, and FIG. 4 is a plan view of FIG. 3. 21...Crankshaft, 21a...Crank, 21
a'...Rectangular engagement hole, 21b...Shaft portion, 21b'...Square shaft portion, 22...Spring, 23...Pressure plate.

Claims (1)

[Claims] 1 The shaft part of the crank engaging part of the crankshaft is formed into a square shape, the engagement hole of the crank is formed into a rectangular shape that is longer than the above-mentioned square shape only in the eccentric direction, and the square part is formed into the engagement hole of the crank in the eccentric direction of the crank. A spring, which is slidably inserted into the crankshaft and compressed with an initial force greater than the maximum load that acts during compression during steady operation, is inserted into the space of the engaging portion so as to press and hold a predetermined amount of eccentricity of the crank; A reciprocating compressor characterized by reducing the eccentricity of the crank when a load greater than the initial force of the spring is applied during compression.