Positive cam type compressor
FIELD OF THE INVENTION 
     This invention relates to a positive cam type rotary compressor wherein a positive cam makes a movable isolator plate reciprocate so as to circulate lubricating oil. The compressor may be generally utilized in an air-conditioner for a car. 
     BACKGROUND 
     Recently, it is required to lessen car accessories such as a compressor for a car air-conditioner as regards size and weight, because the receiving space and total weight of the car accessories are extremely restricted in order to increase the efficiency of the car. A swash plate type compressor is highly valued, as it is more efficient than a reciprocating type compressor, and it only generates very little noise and vibration. But, it is difficult to lessen the number of parts and the size and weight of the said swash plate type compressor due to its peculiar construction. On the other hand, the reciprocating compressor is inferior in characteristics of vibration and noise, and has constructional deficiencies similar to that of the swash plate type compressor. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a compressor of novel type that is small and light, and can be constructed with relatively few parts. 
     Another object is to provide a compressor of high efficiency which only generates a very slight noise and vibration. 
     Numerous other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings which show the preferred embodiment. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings: 
     FIG. 1 is a horizontal sectional view of a positive cam type compressor, 
     FIG. 2 is a simplified diagram of the compressor showing the flow of lubricating oil, 
     FIG. 3 is a simplified diagram of the compressor showing the relation between a movable isolator plate and valves, 
     FIG. 4 is a perspective view of the isolator plate, 
     FIG. 5 is a right side view of a positive cam, 
     FIG. 6 is a front view of the positive cam of FIG. 5, 
     FIG. 7 is a perspective view of the compressor of FIG. 1 with some portions being cut out, 
     FIG. 8 is a simplified diagram of the compressor showing figures of the isolator plate and valves, 
     FIG. 9 is a simplified diagram of the compressor showing the arrangement of isolator and passages, 
     FIG. 10 is a functional diagram of the compressor showing how the suction and compression processes are repeated, 
     FIGS. 11 to 14 are sectional views of movable isolator plates of modified forms, 
     FIG. 15 is a front view of a positive cam of another form, 
     FIG. 16 is a top plan view of the cam of FIG. 15, 
     FIG. 17 is a perspective view of a positive cam type of another embodiment of the present invention, and 
     FIGS. 18 to 21 are perspective views of parts of the compressor of FIG. 17. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIGS. 1 and 7, a cylinder block 1 of cylindrical shape is provided with a front housing 3 and a rear housing 4 at each end. One valve plate 2 is interposed between the cylinder block 1 and the front housing 3. The rear housing is closed to the cylinder block 1 by another valve plate 2. A positive cam 6 is fixed to a drive shaft 7 arranged at the center of a cylinder 5. The cylinder 5 is closed at each end by said valve plates 2. The positive cam 6 is composed of a cylindrical central portion f and a helical disk portion. The driver shaft 7 passes through the central portion f coaxially. The helical disk portion is twisted as shown in FIG. 5, and slidably fitted in a slide groove 9 of a movable isolator plate 10. The positive cam 6 is provided with a seal ring 22 on its periphery as shown in FIGS. 5, 6 and 20. The positive cam 6 and the isolator plate 10 are in sliding relation with one another, so that the isolator plate 10 can be reciprocated along the axis of the cylinder 5 by the positive cam 6 when it rotates in the cylinder cavity, contacting the inner faces of cylinder 5 and the valve plates. The sealing effect between cam 6 and isolator plate 10 is assured by seal member 8. 
     The movable isolator plate defines single or plural operating compartments 8 in the cylinder 5. In the present embodiment, the cylinder cavity is divided into two equal compartments a by two isolator plates 10 disposed diametrically. Accordingly, suction and compression stages are repeated in each operating compartment a as shown in FIG. 10, when the positive cam 6 is rotated by the driver shaft 7. The outer edge portions of isolator plates 10 are slidably fitted into guide grooves 12, which are formed on the opposite inner faces of cylinder 5. 
     Both the front housing 3 and the rear housing 4 have two plate casings 11, which communicate with the guide grooves 12 and angular guide holes 27 shown in FIGS. 18 and 19. Each end portion of isolator plate 10 can enter the casing 11 of front housing 3 and that of rear housing 4 alternately through said guide holes 27 of valve plates 2, when it moves reciprocatively. Each plate casing 11 communicates with a lubricating oil tank 13 of the housing via oil feeding hole 14. Valve plate 2 has at least one suction valve 15 at one edge of the guide hole, and at least one exhaust valve 19 at the other edge of the guide hole 27. As there are two guide holes, there are two pairs of valves 15 and 19. 
     The front housing 3 has two charge chambers 16 1  with which the suction valve 15 communicates, and two discharge chambers 16 2  with which the exhaust valve 19 communicates. A suction pipe 18 is connected to the charge chamber 16 1   with an inlet passage 17 1 , and the discharge chamber 16 2  is connected to an exhaust pipe 20 by an outlet passage 17 2 . Also, the rear housing 4 is provided with the same chambers 16 1  and 16 2 . 
     Referring to FIGS. 2, 3 and 4, when the positive cam 6 rotates throughout the angle of 360°, the contact portion b of positive cam 6 moves to the position c, and the movable isolator plate 10 moves to the position d. Each isolator plate 10 can act as a plunger in the plate casing 11. When the isolator plate 10 enters the casing 11, it positively pushes the lubricating oil e stored in the casing. A requisite quantity of the compressed oil is fed to the seal member 8 that contacts the positive cam 6, and to all other portions that contact the cylinder wall, the guide groove 12 or the valve plate 2. This oil feeding is performed by way of a network of oil channels 21 that is formed in the isolator plate 10. 
     When the cam 6 rotates once again through the angle of 360°, the plate 10 can return to the first position. Thus, when the isolator plate 10 gets out of the casing 11, an adequate sucking phenomenon occurs, so that the lubricating oil e can be withdrawn from the above portions to the casing 11 and/or the oil tank 13. The circulation of lubricating oil depends upon the pumping action, which is caused by the fact that the oil tank 13 communicates with the plate casing 11 by the oil feeding hole 14 of narrow diameter. 
     Referring to FIGS. 8 and 9, both the suction valve 15 and the exhaust valve 19 should be disposed in the proximity of the movable isolator plate 10 in sequence of suction and exhaust. There are two sets of suction valves 15, and also two sets of exhaust valves 19. Each set is composed of three valves which are arranged in a line. The suction and exhaust operations can be performed very smoothly, giving adequate consideration to the opening area of the valve, and to the cross section of isolator plate 10. Namely, valve holes of suction valve 15 and exhaust valve 19 should be made in several sizes correspondingly to the shape of the contacting portion b of cam 6. And the isolator plate 10 should have a sectorial section so as to match the contacting portion b. 
     In order to ensure smooth motions of cam 6 and plate 10, all contact portions of seal member 8 are preferably rounded, and a ball 23 is fitted in the corner of seal member 8 as shown in FIGS. 11 and 12. In FIG. 12, a roll 24 is used as a seal element. In FIG. 13, there is used a tapered roll 24 of arched cross section. In FIGS. 14 and 20, seal members 8 are fitted in a groove 26, and supported by a waved spring 25. Corners g of the seal members 8 of FIG. 14 are rounded. In FIG. 16, the portion b that contacts the valve plate 2 is provided with a seal member 8 or suitable anti-friction material. These structures are designed to smooth the motions of cam 6 and plate 10. In FIGS. 18 and 19, numerals 28 and 29 designate a gasket and a bearing, respectively. The numeral 31 designates a rear block having an oil-gas separator of mesh type. In this embodiment, lead valves are used as exhaust valves 19, and lubricating oil tank is disposed at the lower portion of cylinder block 1. Numerals 30 and 32 designate a seal ring and service valve, respectively. 
     According to the present invention, there can be obtained a relatively small and light compressor adapted for use with a car air conditioner. Furthermore, it is possible to greatly decrease the number of parts of the compressor. Also, the positive cam type compressor of the present invention is superior in characteristics of vibration and noise. It should be understood that the pulsation of the exhaust pressure can be adequately diminished by changing the number of movable isolator plates. The use of the present compressor is not restricted to a vehicle. The construction of the invention can be utilized in making an industrial compressor of large capacity. Furthermore, the substance to be compressed is not limited to a refrigerant or cooling medium. The present invention can be obviously utilized in a compressor of air, water, oil, and the like. 
     Other embodiments of the invention employing the same or equivalent principles may be made by those skilled in the art without departing from the present invention.