Site News  |   Monitor Keywords  |   Monitor Archive  |   Organizer  |   Account Info  |

Piston type compressor

Piston type compressor description/claims

The present invention relates to a piston type compressor using a rotary valve, and more particularly, to a piston type compressor having a structure for bypassing gas remaining in a high-pressure side compression chamber after discharging is completed into a low-pressure side compression chamber.

Patent document 1 discloses a piston type compressor in which a rotation shaft rotates to reciprocate a piston in each cylinder bore. As a result, gas is drawn from a suction pressure region into compression chambers through a rotary valve, compressed in the compression chambers, and then discharged from the compression chambers. During a suction stroke, a suction communication passage of the rotary valve, which rotates in synchronization with the rotation shaft, sequentially communicates the suction pressure region with a passage extending from each compression chamber. The suction communication passage is elongated and extends in the axial direction of the rotary valve and has a uniform width.

An outer circumferential surface of the rotary valve includes a residual gas bypass groove that communicates a guide passage for a high-pressure side compression chamber after discharging is completed to a guide passage for a low-pressure side compression chamber. Non-discharged gas remaining in the compression chamber after discharging is completed, that is, residual gas, is bypassed or recovered in the low-pressure side compression chamber through the high-pressure side guide passage, the residual gas bypass groove, and the low-pressure side guide passage. This reduces re-expansion of gas in the compression chambers that occurs during the suction stroke. This ensures that gas is drawn from the suction pressure region into the compression chambers and improves the volumetric efficiency of the piston type compressor.

In the above piston type compressor, the passage of gas from a high-pressure opening of the residual gas bypass groove to the suction communication passage of the rotary valve via the guide passages in a cylinder block must be prevented. For this purpose, a seal region is formed in the outer circumferential surface of the rotary valve facing the guide passages of the cylinder block. The seal region closes the guide passages of the cylinder block between the high-pressure opening of the residual gas bypass groove and the suction communication passage of the rotary valve.

FIGS. 11 and 12 are development views showing a rotary valve 100 of which outer circumferential surface 100a is laid out on a plane. A guide passage 101 of a cylinder block is in correspondence with the outer circumferential surface 100a of the rotary valve 100. As shown in FIG. 11, the outer circumferential surface 100a of the rotary valve 100 has a seal region S. The seal region S is required to have an area that is large enough to close an opening 101a of the guide passage 101 in the cylinder block between a high-pressure opening 103a of a residual gas bypass groove 103 and an opening 102a of a suction communication passage 102 of the rotary valve.

As the area of the seal region S increases, a seal width W between the high-pressure opening 103a and the suction communication passage 102 increases in the rotation direction of the rotary valve 100. In other words, the high-pressure opening 103a becomes more distant from the opening 102a of the suction communication passage 102. This increases the time difference between when the opening 101a of the guide passage 101 in the cylinder block comes into communication with the high-pressure opening 103a and the when the opening 101a of the guide passage 101 comes into communication with the opening 102a of the suction communication passage 102 in the rotary valve. The increase in the time difference indicates an increase in the time between when the gas in a high-pressure side compression chamber is recovered and when gas is drawn into the high-pressures side compression chamber. As a result, the timing at which gas is drawn into the compression chamber is delayed. This decreases the amount of gas drawn into the compression chambers and lower the compression efficiency.

Therefore, the area of the seal region S may be reduced, or more specifically, the seal width W may be reduced as shown in FIG. 12. This would reduce the time difference between the timing at which the opening 101a of the guide passage 101 in the cylinder block starts communicating with the high-pressure opening 103a and the timing at which the opening 101a of the guide passage 101 starts communicating with the opening 102a of the suction communication passage 102 in the rotary valve.

However, the seal region S is required to close the opening 101a of the guide passage 101 in the cylinder block. Thus, if the area of the seal region S is just reduced, this would reduce the size of the opening 101a in the guide passage 101. This is not desirable because the smaller opening 101a would increase the suction loss of the gas drawn into the compression chambers and lower the compression efficiency.

It is an object of the present invention to provide a piston type compressor that reduces the suction loss of gas drawn into a compression chamber and improves the compression efficiency while advancing the timing for starting the suction of gas into the compression chamber.

One aspect of the present invention is a piston type compressor including a rotation shaft, a cylinder block having a plurality of cylinder bores arranged around the rotation shaft, a piston accommodated in each of the cylinder bores, and a rotary valve rotated in synchronization with the rotation shaft. The piston defines a compression chamber in the cylinder bore. The cylinder block has a plurality of suction ports, each of which communicates a suction pressure region to the corresponding compression chamber. The piston reciprocates between a bottom dead center that maximizes the volume of the compression chamber and a top dead center that minimizes the volume of the compression chamber so as to draw gas from the suction pressure region into the compression chamber through the rotary valve, compress the gas in the compression chamber, and discharge the gas from the compression chamber. The rotary valve has a suction communication passage and a residual gas bypass passage. The rotary valve is rotated so that the suction communication passage sequentially communicates each of the suction port with the suction pressure region and so that the residual gas bypass passage communicates the suction port corresponding to the compression chamber at the high-pressure side after discharging has been performed with the suction port corresponding to the compression chamber at the low-pressure side. A portion of an outer circumferential surface of the rotary valve facing openings of the suction ports forms a seal region that prevents the residual gas bypass passage from being communicated with the suction communication passage through the openings of the suction ports.

Each of the suction ports has a narrow passage located at a top dead center side and a wide passage located at a bottom dead center side. The narrow passage has an opening facing the outer circumferential surface of the rotary valve with a width in a rotation direction of the rotary valve that is smaller than a width of an opening of the wide passage. The opening of the narrow passage has a first preceding end and a first succeeding end. The suction communication passage of the rotating rotary valve first passes by the first preceding end and then passes by the first succeeding end. The opening of the wide passage has a second preceding end and a second succeeding end. The suction communication passage of the rotating rotary valve first passes by the second preceding end and then passes by the second succeeding end. The suction communication passage passes by the first succeeding end before passing by the second succeeding end. The residual gas bypass passage has a high-pressure opening. The high-pressure opening faces only the narrow passage of the suction port that corresponds to the high-pressure side compression chamber when in communication with the suction port. The narrow passage is arranged to enable communication with the compression chamber defined by the piston located at the top dead center. A width between the first succeeding end and the second preceding end in the rotation direction of the rotary valve is smaller than a dimension of a portion of the seal region between the high-pressure opening and an opening of the suction communication passage. The opening of the suction communication passage comes into communication with the wide passage immediately after the narrow passage is closed by the seal region.

Each of the suction ports may have a wide passage located at the top dead center side and a narrow passage located at the bottom dead center side. The wide passage may be arranged continuously with the narrow passage.

FIG. 1 is a vertical cross-sectional view showing a piston type compressor according to a first embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along line 1-1 in FIG. 1;

FIG. 3 is a diagram showing a rotary valve of FIG. 1 of which outer circumferential surface is laid out on a plane;

• Provisional Patent
• Utility Patent

• What Is a Patent?
• What Is a Trademark or Servicemark?
• What Is a Copyright?
• Patent Laws