| Swach plate type variable displayment compressor for supercritical refrigeration cycle -> Monitor Keywords |
|
|
 
Swach plate type variable displayment compressor for supercritical refrigeration cycleRelated Patent Categories: Pumps, Three Or More Cylinders Arranged In Parallel, Radial, Or Conical Relationship With Rotary Transmission AxisSwach plate type variable displayment compressor for supercritical refrigeration cycle description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060083628, Swach plate type variable displayment compressor for supercritical refrigeration cycle. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The present invention relates to a swash plate type variable capacity compressor which is used for a supercritical refrigerating cycle. BACKGROUND ART [0002] Conventionally, various structures are known for a suction valve and a discharge valve of a swash plate type variable capacity compressor which compresses a refrigerant of a refrigerating cycle. For example, it is known that the discharge valve has a valve body press-contacted in an elastically deformed state to the valve seat of a discharge port. The structure of this type of discharge valve is disclosed in, for example, Japanese Utility Model Laid-Open Publication No. Sho 61-44074 and Japanese Patent Application Laid-Open Publication No. 2001-153000. [0003] Besides, the refrigerant of the refrigerating cycle is mixed with a lubricating oil, and it is necessary to consider the surface tension of the lubricating oil which enters the gap between the valve body and the valve seat in order to secure good opening and closing operations of the suction valve and the discharge valve. The surface tension of the lubricating oil is important to secure the hermeticity of the valve but becomes a resistance when the valve body opens. Therefore, if the surface tension is larger than it is required, the valve body operates with delay, and vibrations and noises of the compressor increase. Japanese Patent Laid-Open Publications No. Hei 7-167058 and No. Hei 7-180662 disclose a valve structure which is configured to leave a small gap between the valve body and the valve seat even when the valve body is in a closed state in order to deal with the problems. The suction valve and the discharge valve of the swash plate type variable capacity compressor used for the refrigerating cycle were considered important to have a structure which should prevent vibrations, noises and the like. [0004] As the refrigerant for the refrigerating cycle, a fleon refrigerant including a substitute fleon has been used extensively. But developments are being made to replace it with CO.sub.2 considering the global environment in these years. A refrigerating cycle using CO.sub.2 as the refrigerant has a very high inner pressure in comparison with the refrigerating cycle using a fleon refrigerant, and particularly a pressure on a high-pressure side happens to exceed the critical point of the refrigerant depending on use conditions such as a temperature. The critical point is a limit on the high-pressure side (namely, a limit on a high-temperature side) in a state that a gas layer and a liquid layer coexist and is an end point at one end of a vapor pressure curve. A pressure, a temperature and a density at the critical point become a critical pressure, a critical temperature and a critical density, respectively. Especially, when the pressure exceeds the critical point of the refrigerant in a radiator of the refrigerating cycle, the refrigerant does not condensate. This type of supercritical refrigerating cycle is mounted on, for example, an automobile and used for air conditioning of the car interior. [0005] A compressor to be used for the supercritical refrigerating cycle is also described in, for example, Japanese Patent Laid-Open Publication No. 2002-257037. The compressor described in this publication is configured such that the piston stroke is variable depending on the inclination of a swash plate which is disposed rotatably. The piston is held to be reciprocally movable in the cylinder, and the cylinder is provided with a suction valve for sucking a refrigerant and a discharge valve for discharging the refrigerant. The refrigerant which circulates the refrigerating cycle is sucked into the cylinder through the suction valve, compressed and discharged out of the cylinder through the discharge valve. For the refrigerating cycle used for air conditioning of a car interior, the compressor is coupled with a motor vehicle engine and operated by the engine power. [0006] The supercritical refrigerating cycle has a pressure resistance performance which is quite different from the conventional refrigerating cycle using the fleon refrigerant, and the compressor for the supercritical refrigerating cycle has been also demanded to have a more outstanding structure considering its pressure resistance performance and the like. [0007] For example, according to the above-described Japanese Patent Laid-Open Publication No. 2002-257037, the compressor for the supercritical refrigerating cycle has a high operating pressure. Therefore, even a leakage of the refrigerant through a small gap degrades the performance. And, the compressor described in this publication is provided with an elastic member which pushes the valve body of the suction valve against the valve seat to eliminate a gap which is produced between the valve body and the valve seat. [0008] However, when an elastic member for pushing the valve body against the valve seat is provided, the number of parts increases, which result in causing disadvantages of complicating the structure and requiring a precision thereof, an increase in cost and the like. According to the endurance test conducted by the inventors of the present invention, it was found that the elastic member involves unavoidable problem of causing degradation in endurance. [0009] Besides, for the supercritical refrigerating cycle, the compressor, which is operated by the power of a motor vehicle engine, is important to secure a startup property when the driving engine is started. In other words, when this compressor is compared with a compressor of the refrigerating cycle using a fleon refrigerant, the cylinder capacity becomes relatively small because of a problem of pressure resistance. Therefore, an influence of the leakage of the refrigerant at the suction valve or the discharge valve is conspicuous and the seat surfaces of the valve body and the valve seat also become small. And, there are problems that the lubricating oil which enters between them becomes rather insufficient, and good opening and closing operations of the valve body are hardly secured. And, a seat failure due to such a shortage of the oil becomes a cause of delaying the generation of suction and discharge actions of the refrigerant from particularly a pressure-balanced state (with a very small flow rate of the refrigerant). Thus, it is presumed that with the existing compressor, the number of rotations on startup, namely the number of rotations of the swash plate when the refrigerant is started to be compressed, is larger than it is required. [0010] As a compressor to be mounted on a car, there is known a clutchless compressor which is coupled with a motor vehicle engine without via a clutch. For the clutchless compressor, its swash plate is rotating constantly even when the refrigerant is not compressed, and the piston's minimum stroke is generally about 5% or less of the maximum stroke. In recent years, such a clutchless compressor has been also regarded as having a significant problem that the number of rotations on startup is decreased. [0011] Especially, with the supercritical refrigerating cycle, the refrigerant has a pressure of about 7.2 MPa in an atmosphere of 30.degree. C. when the compressor is actuated. On the contrary, with the refrigerating cycle using a fleon refrigerant, the refrigerant has a pressure of about 0.67 MPa in an atmosphere of 30.degree. C. when the compressor is actusted. Therefore, the compressor of the supercritical refrigerating cycle secures a high pressure resistance by setting the cylinder capacity and the port opening area small. Generally, the compressor of the supercritical refrigerating cycle has a cylinder with a bore diameter of 15.0 to 21.0 mm, a capacity of 20 to 33 cm.sup.3, and a suction valve and a discharge valve with a port's opening area of 7.0 to 29.0 mm.sup.2. On the contrary, the compressor of the refrigerating cycle using the fleon refrigerant has a cylinder with a bore diameter of 32 to 40 mm, a capacity of 90 cm.sup.3 to 170 cm.sup.3, and a suction valve and a discharge valve with a port's opening area of 38.5 to 113.0 mm.sup.2. [0012] Further, when the compressor of the supercritical refrigerating cycle and the compressor of the refrigerating cycle using the fleon refrigerant have the same machining accuracy for the cylinder and the piston, the supercritical refrigerating cycle has a relatively large gap between the cylinder and the piston with respect to the cylinder capacity when the piston reaches the top dead center. This is also one of the causes to increase the number of rotations at the time of actuation of the supercritical refrigerating cycle. [0013] The present invention has been made in view of the above circumstances and an object is to achieve an improvement of performance of a swash plate type variable capacity compressor for a supercritical refrigerating cycle. DISCLOSURE OF THE INVENTION [0014] The invention described in claim 1 of the present application is a swash plate type variable capacity compressor to be used for a supercritical refrigerating cycle comprising: a swash plate which is disposed rotatably, a piston which is coupled with the swash plate and a cylinder which holds the piston movably, the cylinder is provided with a suction valve for sucking a refrigerant of the supercritical refrigerating cycle and a discharge valve for discharging the refrigerant, wherein the suction valve has valve bodies having flexibility attached to suction ports for sucking the refrigerant, and the swash plate type variable capacity compressor has the valve bodies press-contacted in an elastically deformed state against the valve seats of the suction ports to decrease the number of rotations of the swash plate when the refrigerant is started to be compressed. With this structure, the performance of the swash plate type variable capacity compressor for a supercritical refrigerating cycle is improved securely. [0015] The inventors of the present invention have prototyped various types of valve structures and conducted experiments in order to obtain a suitable valve structure for the swash plate type variable capacity displacement compressor for a supercritical refrigerating cycle. According to the conducted experiments, it was found that the elimination of the gaps between the valve bodies and the valve seats described above was more significant for the suction valve than for the discharge valve in view of the reduction of the number of rotations on startup. Further, the suction valve, which was most effective to secure a startup property, endurance and good opening and closing operations of the valve bodies, has the valve bodies having flexibility fitted to the suction ports for sucking the refrigerant and the valve bodies press-contacted in a slightly elastically deformed state against the valve seats of the suction ports. The valve bodies of the suction valve are designed considering an appropriate inner stress applied after fitting to the suction ports. [0016] With this structure, even if the seat surfaces of the valve bodies and the valve seats are rather narrow, such a seat defect can be avoided efficiently. As a result, the number of rotations of the swash plate when the refrigerant is started to be compressed can be decreased securely. [0017] The cases that the valve bodies of the suction valve were press-contacted and not in an elastically deformed state against the valve seats were compared by experiments. The number of rotations on startup in the case of press-contacted was 30 to 70% of that on startup in the case of not press-contacted. In other words, the reduction of the number of rotations of the swash plate when the refrigerant is started to be compressed according to the present invention is based on the comparison with the case that the valve bodies of the suction valve are not press-contacted in an elastically deformed state against the valve seats. [0018] As described above, the present invention has been made with attention paid to a quite significant structure in detail of the swash plate type variable capacity compressor used for a supercritical refrigerating cycle. As a result, the swash plate type variable capacity compressor has achieved a conspicuous effect of considerably improving the performance of the compressor by devising a very simple structure. [0019] The invention described in claim 2 of the present application is the swash plate type variable capacity compressor according to claim 1, wherein the valve body has deflection of 1 mm or less when the valve bodies are fitted to the suction ports, and the valve bodies receive an external force of 1.8 N or less from the valve seats of the suction ports. In other words, the seating property of the valve bodies and the valve seats can be secured finely, while securing the smooth opening and closing operations of the valve bodies, by determining the deflection of the valve bodies to 1 mm or less and the external force received by the valve bodies from the valve seats of the suction ports to 1.8 N or less. [0020] The invention described in claim 3 of the present application is the swash plate type variable capacity compressor according to claim 1 or 2, wherein the supercritical refrigerating cycle is a refrigerating cycle for air conditioning of a car interior to be mounted in an automobile, and the swash plate type variable capacity compressor is a clutchless compressor which is coupled with a motor vehicle engine without via a clutch. In other words, the swash plate type variable capacity compressor of the present invention has securely reduced the number of rotations of the swash plate when the refrigerant is started to be compressed and can be used quite suitably as a clutchless compressor used for a refrigerating cycle for air conditioning of a car interior. BRIEF DESCRIPTION OF THE DRAWINGS Continue reading about Swach plate type variable displayment compressor for supercritical refrigeration cycle... Full patent description for Swach plate type variable displayment compressor for supercritical refrigeration cycle Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Swach plate type variable displayment compressor for supercritical refrigeration cycle patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. 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 Swach plate type variable displayment compressor for supercritical refrigeration cycle or other areas of interest. ### Previous Patent Application: Vapor compression system including a swiveling compressor Next Patent Application: Piston pump Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the Swach plate type variable displayment compressor for supercritical refrigeration cycle patent info. IP-related news and info Results in 0.12875 seconds Other interesting Feshpatents.com categories: Novartis , Pfizer , Philips , Polaroid , Procter & Gamble , 174 |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
