DESCRIPTION Title of Invention ROTARY COMPRESSOR Technical Field [0001] The present invention relates to a rotary compressor for use in a refrigeration cycle of a refrigerating and air-conditioning apparatus, such as an air-conditioning apparatus or a refrigerator, for compressing refrigerant gas. Background Art [0002] To fit an eccentric portion of a compressor to a piston of the compressor in assemblage, the piston and the eccentric portion need to be sized such that a value obtained by subtracting an eccentric amount of an eccentric portion from a radius of a main shaft or a radius of an auxiliary shaft be equal to or larger than a radius of the eccentric portion. If the value obtained by subtracting the eccentric amount of the eccentric portion from the radius of the main shaft or the radius of the auxiliary shaft is smaller than the radius of the eccentric portion, interference between an outer diameter of the eccentric portion and an inner diameter of the piston inhibits fitting the piston to the eccentric portion in inserting the piston to the eccentric portion to pass the main shaft or the auxiliary shaft over. [0003] To increase the displacement volume to achieve an extended capability of the compressor, an outer diameter of the piston needs to be reduced and the eccentric amount needs to be increased. However, the above-stated restriction upon fitting the piston to the eccentric portion imposes a problem in that the eccentric amount of the eccentric portion cannot become so large that the value obtained by subtracting the eccentric amount of the eccentric portion from the radius of the main shaft or the radius of the auxiliary shaft is smaller than the radius of the eccentric portion. [0004] To overcome the above-mentioned problem, hitherto, a rotary compressor having the following configuration has been disclosed. Specifically, an outer diameter of an auxiliary shaft of a crankshaft is set to be smaller than an outer diameter of a main shaft of the crankshaft, and a value obtained by subtracting an eccentric amount of an eccentric portion from a radius of the auxiliary shaft is equal to or larger than a radius of the eccentric portion (see, for example, Patent Literature 1). Citation List Patent Literature [0005] Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2011-127430 Summary of Invention Technical Problem [0006] However, in the rotary compressor disclosed in Patent Literature 1, when the displacement volume is increased, in other words, when the outer diameter of the piston is reduced and the eccentric amount of the eccentric portion is increased, no consideration is given on a relationship between the displacement volume and an oil supply hole that is formed in a crankshaft and is essential to supply oil into a compression mechanism unit including the crankshaft, a main bearing, an auxiliary bearing, a cylinder, the piston, and a vane. [0007] When the eccentric amount of the eccentric portion is increased in order to increase the displacement volume, because of the above-mentioned limitation that is involved when the piston is fitted to the eccentric portion, it is necessary to reduce the outer diameter of the auxiliary shaft in accordance with the increase in eccentric amount. When the outer diameter of the auxiliary shaft having the oil supply hole formed therein is reduced, rigidity of the auxiliary shaft is reduced, and an amount of flexure of the auxiliary shaft caused by a gas load that is generated when refrigerant gas is compressed in a compression chamber is increased. Further, lubricating conditions of the bearings are degraded, and there is a fear in that a seizure occurs between the crankshaft and the bearings during operation of the compressor, thereby causing shutdown of the compressor and disabling restart of the compressor. [0008] Further, in order to increase an efficiency of the compressor, a height of the cylinder is reduced, and a height of the piston configured to seal a high-pressure side and a low-pressure side of the compression chamber is also reduced. In this manner, the refrigerant gas on the high-pressure side is prevented from leaking into the low-pressure side through a gap between the piston and an inner wall of the cylinder. Thus, degradation of the efficiency resulting from reduction in weight flow rate of the refrigerant gas to be sucked can be remedied. However, in order to reduce the height of the cylinder with the same displacement volume, it is necessary to reduce the outer diameter of the piston and to increase the eccentric amount of the eccentric portion of the crankshaft. Because of the need, when the outer diameter of the auxiliary shaft having the oil supply hole formed therein is reduced as described above, rigidity of the auxiliary shaft is reduced, and the amount of flexure of the auxiliary shaft caused by the gas load when the refrigerant gas is compressed in the compression chamber is increased. Further, the lubricating conditions of the bearings are degraded, and there is a fear in that a seizure occurs between the crankshaft and the bearings during operation of the compressor, thereby causing shutdown of the compressor and disabling restart of the compressor. [0009] The present invention has been made in order to solve the above-mentioned problem, and has an object to provide a high-powered and high-efficiency rotary compressor capable of increasing a displacement volume of the compressor or increasing an efficiency of the compressor with the same displacement voiume while maintaining reliability of causing no seizure of bearings. Solution to Problem [0010] According to one embodiment of the present invention, there is provided a rotary compressor, including: an electric motor comprising a rotator; a crankshaft rotated by the rotator; and a compression mechanism unit driven by the crankshaft, the crankshaft comprising a main shaft fixed to the rotator, an auxiliary shaft formed along an axial direction of the main shaft, and an oil supply hole for oil supply, which is formed in the crankshaft, wherein cpd/cpD is 0.7 or less where cpD is an outer diameter of the auxiliary shaft and cpd is a diameter of the oil supply hole. Advantageous Effects of Invention [0011] According to the rotary compressor of one embodiment of the present invention, when cpD represents the outer diameter of the auxiliary shaft and cpd represents the diameter of the oil supply hole, the value of cpd/cpD is set to 0.7 or less. Accordingly, rigidity of the auxiliary shaft is enhanced, and an amount of flexure of the auxiliary shaft caused by a gas load when the refrigerant gas is compressed in the compression chamber is reduced. Further, lubricating conditions of the bearings are not degraded, and a seizure does not occur between the crankshaft and the bearings during operation of the compressor. Thus, the displacement volume of the compressor can be increased, or an efficiency of the compressor can be increased with the same displacement volume while maintaining reliability of causing no seizure of the bearings. As a result, the high-powered and high-efficiency compressor can be achieved. Brief Description of Drawings [0012] [Fig. 1] Fig. 1 is a schematic view for illustrating a configuration of a rotary compressor according to Embodiment 1 of the present invention. [Fig. 2] Fig. 2 is a side view for illustrating a crankshaft of the rotary compressor according to Embodiment 1 of the present invention. [Fig. 3] Fig. 3 is a table for showing a relationship between a value of