Patent Publication Number: US-2012034124-A1

Title: Compressor and kit repairing and inflating inflatable articles

Description:
TECHNICAL FIELD 
     The present invention relates to an improved, direct-current or DC vane compressor for a kit for repairing and inflating inflatable articles, in particular tyres, and to a kit comprising such a compressor. The compressor also applies non-limitingly to 12V systems used for a wide range of two- and/or four-wheel vehicle applications, as opposed to hobby applications, and/or to applications that call for a silent-operating, DC compressor with a wide 1-10 bar pressure range and low 7-30 ampere absorption. 
     A tyre repair and inflation kit is preferably compact, for easy handling by any user, and silent-operating. 
     High delivery pressure enables fast inflation of automobile, motorcycle and even commercial vehicle tyres, but should not increase the size of the kit, for the reason given above, or increase electric current absorption, to avoid overloading the vehicle&#39;s electric system, which could discharge the battery and at least temporarily affect the reliability of on-vehicle equipment. Moreover, vehicle electric systems are low-current, which means equipment powered by them must also be capable of efficient, low-current operation. 
     A need is felt for compressors of simple design, with a small number of component parts, designed to meet increasing demand in the automobile market for low-cost technology, and which are therefore cheap to produce. A miniaturized compressed-air vane compressor, of improved performance as compared with ordinary alternating compressors and as yet not employed in automobiles, could have big advantages in terms of performance, silent operation, and scope. 
     The most obvious hurdles in miniaturizing such a low-cost compressor, which would have to operate with no lubrication, are substantially: 
     1) the materials to use, which must be low-friction, with a sufficient temperature gradient; 
     2) optimum sealing between the assembled parts, in particular between the rotor and stator, between the vanes and rotor, and therefore between the vanes and stator; 
     3) sufficiently good efficiency of the air intake and pressurized air to reduce “parasitic air” circulation inside the compressor. 
     The above requirements apply to, and may successfully become characteristic of kits for repairing and inflating inflatable articles, but also apply to other applications as well. 
     DISCLOSURE OF INVENTION 
     It is an object of the present invention to provide a vane compressor designed to at least partly meet the above requirements. 
     According to the present invention, there is provided a vane compressor as claimed in claim  1 . 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A preferred, non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: 
         FIG. 1  shows a view in perspective of a kit which may be fitted with a compressor in accordance with the present invention; 
         FIG. 2  shows an axial section of a vane compressor in accordance with the present invention; 
         FIG. 3  shows a section along line in  FIG. 2 ; 
         FIG. 4  shows a longitudinal section of a component part of the  FIG. 2  compressor; 
         FIG. 5  shows a section along line V-V in  FIG. 4 ; 
         FIG. 6  shows a section along line VI-VI in  FIG. 4 ; 
         FIG. 7  shows performance graphs of a compressor in accordance with the present invention. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Number  1  in  FIG. 1  indicates as a whole a kit for repairing and inflating inflatable articles, and which is purely a non-limiting example of one application of the present invention. Kit  1  comprises a casing  2 ; a compressor assembly (described in detail below) housed in casing  2 ; and a canister assembly  3  connected releasably to the compressor assembly, e.g. as described and illustrated in International Patent WO-A1-2008001179 filed by the present Applicant. 
     More specifically, casing  2  comprises a substantially parallelepiped-shaped portion  4  for housing the compressor assembly; and a projecting portion  5  projecting from the front of portion  4  and defining a seat for at least partly housing canister assembly  3 . 
     Canister assembly  3  contains a sealing fluid for repairing tyre punctures, and comprises a bottle  6  inverted in use; and a hose  7  connected to bottle  6  to feed the sealing fluid into the tyre. 
     Kit  1  also comprises a second hose  8  connected directly to the compressor assembly to inflate the tyre without injecting sealing fluid; and control means for selecting a repair mode, in which hose  7  and bottle  6  are connected to the compressor assembly, and an inflation mode, in which hose  8  is connected to the compressor assembly. The control means comprise, for example, a valve  12  switched by a knob  9  on casing  2 , and having two outlets connected to canister assembly  3  and hose  8  respectively. 
     Kit  1  also comprises a power plug for powering a DC, i.e. direct-current, electric motor (not shown) of the compressor assembly from a vehicle electric system; and a switch  11  for turning the compressor assembly on. 
     According to the present invention, the compressor assembly comprises a rotary vane compressor  13  for producing compressed air for injection into the tyre, either via bottle  6  and hose  7  to make repairs, or via hose  8  to simply inflate the tyre. 
     More specifically, compressor  13  comprises a cylindrical pump body  14  defining a cavity  15 ; a rotor  16  housed in cavity  15 ; and an input shaft  17 , of axis A, powered by the electric motor and connected to rotor  16 . 
     Pump body  14  comprises a central block  18  defining cavity  15 ; and two flanges  19 ,  20  fixed to opposite sides of central block  18 . Flanges  19 ,  20  are positioned angularly with respect to block  18  by a number of pins P; and respective sealing rings G are inserted to seal cavity  15 . 
     Input shaft  17  has a projecting portion  21  projecting from flange  19  and connected to rotor  16  at least to rotate integrally with rotor  16 . On the longitudinally opposite side of rotor  16  to projecting portion  21 , input shaft  17  has a pin  23  supported radially on flange  20  by a bearing  24 . Similarly, projecting portion  21  is supported radially on flange  19  by a bearing  25 ; and rotor  16 , projecting portion  21 , and pin  23  are preferably formed in one piece. 
     As shown in  FIG. 3 , compressor  13  defines an inlet  25  and an outlet  26  connected fluidically to cavity  15 , and through which compressed air generated by rotation of the rotor flows. Accordingly, compressor  13  comprises a number of, e.g. four, vanes  27  housed slidably inside respective seats  28  equally spaced angularly and defined by rotor  16 . In the non-limiting embodiment shown, seats  28  are preferably located along chord portions of the cross section of rotor  16 , as opposed to radially. For example, seats  28  extend beyond the geometric centre of the cross section of rotor  16  with respect to the direction defined by a radius parallel to the sliding direction of vane  27  inside respective seat  28 . 
     According to the present invention, air intake is assisted by the inlet combining a through a hole  29 , and a slot  30  which communicates with and is tangentially larger than hole  29 . More specifically, slot  30  is shallower than the thickness of flange  20 . 
     Preferably, the size of slot  30 , the location of outlet  26 , and the angular distance between each two consecutive vanes  27  are such that no angular position of the rotor connects slot  30  fluidically to outlet  26 . 
     That is, whatever the angular position of rotor  16 , there is always at least one vane  27  interposed between inlet  25  and outlet  26 . As shown in  FIG. 3 , preferably one or two vanes  27  are interposed between inlet  25  and outlet  26 . 
       FIG. 4  shows a non-return valve  31  located in series between cavity  15  and outlet  26 , and which comprises an annular insert  32  screwed inside a radial hole  33  in central block  18 ; a tubular body  34  with a threaded stem  35  screwed inside radial hole  33  to rest against annular insert  32 ; and a movable disk D inside a seat  36  defined between annular insert  32  and threaded stem  35 . 
     More specifically ( FIG. 4 ), annular insert  32  comprises a threaded flange  37  which engages radial hole  33 ; and a tubular portion  38  projecting axially from threaded flange  37 . Threaded stem  35  defines a contoured seat S for housing the whole of tubular portion  38 . According to the present invention, the contoured seat has a number of conduits  39  connected fluidically to outlet  26  and to a passage  40  in annular insert  32 . Preferably, outlet  26  is defined by a preferably cylindrical hole with an axis B; and conduits  39  are straight, and are so located and of such a radius that the geometric surfaces defined by their respective lateral walls interfere with the geometric surface defined by the lateral wall of outlet  26 , thus forming a number of windows  41  connecting outlet  26  to conduits  39 . 
     Contoured seat S of tubular portion  38  is deeper, along axis B, than the height of tubular portion  38 , so that seat  36  of movable disk D is defined between a top face  42  of contoured seat S and an end face  43  of tubular portion  38 . Moreover, tubular portion  38  is smaller in diameter than the largest circle tangent to all of conduits  39 , so that, when disk D is raised, outlet  26  is connected fluidically to cavity  15 . 
     In a preferred embodiment of the present invention, at least pump body  14  and vanes  27  are made of highly wear-resistant, low-friction, non-metal material that can be pressed and/or machined easily, such as carbon-graphite. Generally speaking, other pressable materials of a lower density than metal materials may also be used for non-return valve  31 . 
     By way of a non-limiting example of the application described,  FIG. 7  shows the flow and energy consumption of a compressor, in accordance with the present invention, featuring a 30 mm diameter cavity  15 , a 23 mm diameter rotor  16 , and four vanes. More generally speaking, cavity  15  is less than 50 mm and preferably less than 40 mm in diameter. 
     As can be seen, consumption is low with respect to flow, and the compressor is compact in size. 
     High flow is also and substantially due to leakage being minimized by the design of non-return valve  31  and the angular position of slot  30  with respect to outlet  26 . Slot  30 , conveniently located according to the work point selected according to rotor rotation speed, compressor size and rotor-stator ratio, also improves air intake and the fill coefficient of the variable-volume chambers of compressor  13 . 
     Clearly, changes may be made to the compressor as described and illustrated herein without, however, departing from the scope defined in the accompanying Claims. 
     For example, the number of vanes  27  may range from a minimum of two to a maximum of six. 
     Compressor  13  is preferably non-lubricated, i.e. operates dry or with a small amount of lubrication applied during manufacture. In other words, compressor has no lubrication circuit, and draws untreated outside air.