Suction structure in fixed displacement piston type compressor

The present invention relates to a suction structure for allowing refrigerant into a suction pressure region in a fixed displacement piston type compressor. More specifically, the compressor has a rotary valve that is integrally rotated with a rotary shaft and that has a supply passage for introducing refrigerant from the suction pressure region into a compression chamber defined in a cylinder bore by a piston.

In piston type compressors, there are two types of suction valves. One is a rotary valve as disclosed in Unexamined Japanese Patent Publications No. 7-119631 and No. 2006-083835. The other is a reed type suction valve as disclosed in Unexamined Japanese Patent Publications No. 64-088064 and No. 2000-145629. The piston type compressors including the rotary valves has lower suction resistance in introducing refrigerant into cylinder bores, and has superior energy efficiency, compared to the piston type compressors including the reed type suction valves.

At the start of the compressor disclosed in the above reference No. 7-119631, torque is rapidly increased in accordance with the compression of refrigerant gas, and is applied as a load to a vehicle engine (internal combustion). Thereby the vehicle speed is temporarily decreased at the start of the compressor, and the passengers of the vehicle feel shock.

In the piston type compressor disclosed in the above reference No. 7-119631, the rotary valve is provided so as to be axially movable in the direction of the axis of the rotary shaft. The position of the rotary valve is displaced in accordance with the pressure supplied to a control pressure chamber. A bypass groove is formed in the rotary valve so as to communicate almost all the cylinder bores to a suction port formed at the center of a cylinder block. The rotary valve is located at a position in the axial direction of the rotary shaft in such a manner that almost all the cylinder bores are communicable with the suction port through the bypass groove at the stop and at the start of the compressor. Therefore, even when the piston performs compression of the refrigerant gas in the cylinder bore at the start of the compressor, the refrigerant gas in the cylinder bore is returned to the suction port through the bypass groove. The shock at the start of the compressor does not occur, accordingly.

In order to prevent leakage of the refrigerant gas along the periphery of the rotary valve, and also to allow the rotary valve to rotate, it is required that clearance around the periphery of the rotary valve is set as small as possible However, with the structure in which the rotary valve is movable in the axial direction of the rotary shaft, the rotary valve needs clearance to allow the rotary valve to be movable in the axial direction of the rotary shaft. It is hard to set such clearance appropriately.

A compressor disclosed in Unexamined Japanese Patent Publication No. 7-139474 includes a device for decreasing load at start of the compressor. The device is located in a suction passage connected to a suction chamber. The device includes a spool valve which constitutes an oil damper. Clearance is formed between a damper portion of the spool valve and a housing. When the spool valve is moved in the direction to open the suction passage, oil in a damper chamber is gradually leaked to an intermediate chamber through the clearance. Therefore, the speed of the movement of the spool valve is gradual, and the speed of the opening of the suction passage is gradual. Thereby the shock at the start of the compressor is suppressed.

A compressor disclosed in Unexamined Japanese Patent Publication No. 2000-145629 includes a pressure differential detecting valve which is opened and closed in accordance with the pressure differential between discharge pressure and suction pressure. The pressure differential detecting valve is located between a low-pressure refrigerant passage for introducing refrigerant from the outside of the compressor and a suction chamber in the compressor. When the compressor is started in a state where the pressure in the compressor is balanced, the pressure differential detecting valve is closed, and the flow of the refrigerant from the outside of the compressor into the suction chamber is stopped. Thereby the shock at the start of the compressor is suppressed.

However, in the compressor disclosed in the reference No. 7-139474, the refrigerant is remained in the suction chamber even when the suction passage is closed by the spool valve. The residual refrigerant is introduced into the cylinder bore and compressed therein. In the compressor disclosed in the reference No. 2000-145629, the refrigerant is remained in the suction chamber even when the pressure differential detecting valve is closed. The residual refrigerant is introduced into the cylinder bore and compressed therein. The volume of the suction chamber is set large so as to suppress the suction pulsation. Thereby large amount of refrigerant is introduced into the cylinder bore in a state where the pressure differential detecting valve is closed, or the suction passage is closed, and the effect in suppressing the shock at the start of the compressor is not sufficiently obtained.

The present invention is directed to increase the effect in suppressing the shock at the start of the compressor.

In accordance with the present invention, a suction structure is provided for allowing refrigerant into a suction pressure region in a fixed displacement piston type compressor. The compressor has cylinder bores arranged around a rotary shaft for accommodating a respective piston. A cam body is formed with the rotary shaft. The piston is engaged with a cam body so that the rotation of the rotary shaft is transmitted to the piston. A compression chamber is defined by the piston in the respective cylinder bore. A rotary valve has a supply passage for introducing the refrigerant from the suction pressure region to the compression chamber. The rotary valve is rotated integrally with the rotary shaft. The suction structure includes a shifting device. The shifting device shifts between a connecting state and a disconnecting state. In the connecting state the outlet of the supply passage is connected to the suction pressure region and in the disconnecting state the outlet of the supply passage is disconnected from the suction pressure region. The shifting device includes a valve body, a return spring, a first and a second displacement chambers, and a throttle passage. The valve body is movable between the connecting position and the disconnecting position. The connecting position corresponds to the connecting state and the disconnecting position corresponds to the disconnecting state. The return spring urges the valve body from a connecting position toward a disconnecting position. The first displacement chamber urges the valve body from the disconnecting position to the connecting position. The volume of the first displacement chamber is displacable in accordance with an amount of a fluid inside therein. The volume of the second displacement chamber is displacable. The fluid is filled in the first and the second displacement chambers. The throttle passage connects the first displacement chamber to the second displacement chamber. The volume of the first displacement chamber is increased when the fluid flows from the second displacement chamber to the first displacement chamber through the throttle passage. The volume of the first displacement chamber is decreased when the fluid flows from the first displacement chamber to the second displacement chamber through the throttle passage.

Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention that are believed to be novel are set forth with particularity in the appended claims. The invention together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

FIG. 1 is a longitudinal cross-sectional view of a compressor according to a first preferred embodiment of the present invention;

FIG. 2A is a cross-sectional view which is taken along the line I-I in FIG. 1;

FIG. 2B is a cross-sectional view which is taken along the line II-II in FIG. 1;

FIG. 3 is a partially enlarged cross-sectional view illustrating the suction structure of the compressor in a disconnecting state according to the first preferred embodiment of the present invention;

FIG. 4 is a partially enlarged cross-sectional view illustrating the suction structure of the compressor in a connecting state according to the first preferred embodiment of the present invention;

Continue reading about Suction structure in fixed displacement piston type compressor...
Full patent description for Suction structure in fixed displacement piston type compressor

Brief Patent Description - Full Patent Description - Patent Application Claims

Click on the above for other options relating to this Suction structure in fixed displacement piston type compressor patent application.

Patent Applications in related categories:

20090297369 - Double-headed piston type compressor - A double-headed piston type compressor includes front and rear housings, a cylinder block defining therein a crank chamber and a plurality of cylinder bores and having a shaft hole therethrough, a double-headed piston accommodated in the cylinder bores for reciprocating therein, a rotary shaft rotatably supported by the shaft hole, ...


###


How KEYWORD MONITOR works... a FREE service from FreshPatents
1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored.
3. Each week you receive an email with patent applications related to your keywords.  
Start now! - Receive info on patent apps like Suction structure in fixed displacement piston type compressor or other areas of interest.
###


Previous Patent Application:
Axial piston machine with hydrostatic support of the holding -down device
Next Patent Application:
Oil pump resonator
Industry Class:
Pumps

###

Design/code © 2009 FreshContext LLC/Freshpatents.com. Website Terms and Conditions - Also read: About this Page
Patent data source: patents published by the United States Patent and Trademark Office (USPTO)
Information published here is for research/educational purposes only (and in conjunction with our Keyword Monitor) and is not meant to be used in place of the full USPTO patent document/images or a comprehensive patent archive search. Complete official applications are on file at the USPTO and often contain additional data/images (Freshpatents is currently text-only). FreshPatents.com is not affiliated with or endorsed by the USPTO or firms/individuals or products/designs/ideas related to listed patents.

FreshPatents.com Support
Thank you for viewing the Suction structure in fixed displacement piston type compressor patent info.
IP-related news and info


Results in 2.47558 seconds


Other interesting Feshpatents.com categories:
Medical: Surgery ,  Surgery(2) ,  Surgery(3) ,  Drug ,  Drug(2) ,  Prosthesis ,  Dentistry   paws