Abstract:
Various embodiments of the present disclosure provide a gas-powered fastener-driving tool. In one embodiment, the tool includes a combustion or precombustion chamber a valve comprising a body that is mobile within the combustion or precombustion chamber between a first closed position and a second open position. The body defines two opposing orifices at longitudinal ends of the body. The orifices form part of a bore defined through the body that enables gas to pass through the valve. This makes it possible to limit the pressure drops as gas is being admitted to or exhausted from the chamber, thus making it possible to optimize the duration of the firing cycle of the tool.

Description:
PRIORITY CLAIM 
       [0001]    This patent application claims priority to and the benefit of French Patent Application No. 1562719, which was filed on Dec. 18, 2015, the entire contents of which are incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The present disclosure relates to a combustion or precombustion chamber for a gas-powered fixing tool such as a nail gun for example. 
       BACKGROUND 
       [0003]    The present disclosure relates to anchoring or fixing tools, the to be gas-powered, which means tools comprising an internal combustion engine that works by igniting an air-fuel mixture inside a combustion chamber, the fuel being injected into the chamber by an injection device from a fuel receptacle referred to as a gas cartridge. These tools are intended to drive fixing elements into supporting materials so that components can be fixed thereto. Gas-powered nail guns are very commonplace these days. As examples of fuels for the internal combustion engine, mention may be made of gasoline, alcohol, in liquid and/or gas form. 
         [0004]    In general, this type of tool is portable and comprises a casing in which the internal combustion engine that propels a piston that drives a fixing element is mounted. This type of tool may also comprise an electric battery as well as a holding, handling and firing handgrip on which a trigger by means of which the tool is actuated is mounted. 
         [0005]    A firing cycle comprises several steps such as the distribution of a quantity of fuel via the cartridge, the admission of the fuel into the chamber, the mixing of the fuel with air in the chamber, the ignition and combustion of the mixture in order to drive the piston, and the evacuation of the combustion gases from the chamber. 
         [0006]    A combustion chamber comprises at least one gas intake or exhaust valve. This valve comprises a body that is mobile between a closed first position in which a gas intake or exhaust orifice is closed and an open second position in which this orifice is open. 
         [0007]    The valves used in the state of the art have disadvantages. Specifically, their configurations give rise to significant pressure drops when the gas is being admitted or exhausted, and these lengthen the duration of the firing cycle. A valve is known for example in which the mobile body has an elongate form along an axis and comprises orifices for the passage of gas which are oriented radially with respect to this axis. The gas has to pass radially through these radial orifices then circulate longitudinally along the axis. This winding path leads to the aforementioned pressure drops and has a tendency to slow down the firing cycle of the tool. 
         [0008]    The present disclosure proposes a solution to the problem which is simple, effective and economical. 
       SUMMARY 
       [0009]    The present disclosure thus proposes a combustion or precombustion chamber for a gas-powered fixing tool, comprising at least one valve, such as a gas intake or exhaust valve, the valve comprising a body that is mobile between a first closed position and a second open position, characterized in that the body has a tubular elongate form and comprises an internal bore emerging at the two longitudinal ends of the body to form, respectively, two orifices for the longitudinal passage of gas. 
         [0010]    In the present application, a precombustion chamber is intended to mean a chamber in which precombustion of an air-fuel mixture is intended to take place, before this mixture is injected into a combustion chamber to complete the combustion of the mixture. 
         [0011]    According to the present disclosure, the mobile body of the valve is “hollow” which means that its internal bore is open at the two longitudinal ends of the body. The body thus comprises two axial or longitudinal orifices that enable the gas to circulate more or less in a straight line, and therefore without twists and turns. This makes it possible to limit the pressure drops as gas is being admitted to or exhausted from the chamber, thus making it possible to optimize the duration of the firing cycle of the tool. 
         [0012]    The chamber according to the present disclosure may comprise one or more of the following features, considered in isolation from one another or in combination with one another:
       the body has a generally cylindrical shape;   the body bears, at its outer periphery, at least one seal;   the at least one seal extends in a transverse plane passing substantially through one of the abovementioned two orifices;   the body is mounted to be mobile in longitudinal translation in a casing, in certain embodiments formed by an assembly of parts or of elements;   the casing comprises a first tubular cylindrical element of elongate form in which the body is housed and can slide;   the casing comprises a second cylindrical element configured to be engaged in the body when the latter is in the closed position;   the second element bears, at its outer periphery, at least one seal configured to cooperate with the body, the at least one seal in certain embodiments extending in a transverse plane passing substantially through one of the abovementioned two orifices;   the second element comprises an outer annular flange and is surrounded by a return spring bearing respectively on the flange and on the body, in order to bias the latter into its open position;   the casing comprises a third element comprising an internal bore in which the body is intended to slide, the third element comprising at least one orifice for the passage of gas emerging in this bore and oriented substantially radially relative to the longitudinal axis of the body, this orifice being configured to be blocked by the body when it is in its closed position and left free when it is in its open position;   the body is linked by a member of elongate form to a valve shutter or disc and/or to another mobile body of a valve;   the body is linked to a rectilinear rod extending along the longitudinal axis of the body and having an outer diameter less than the inner diameter of the bore of the body;   the rod is linked by legs to one of the longitudinal ends of the body;   the body is linked either to a sheath having an inner diameter substantially identical to the inner diameter of the bore of the body, or to one or more rectilinear rods extending over a circumference of a diameter substantially identical to that of the body;   the orifices for the passage of gas have circular passage cross sections;   the orifices for the passage of gas have substantially identical passage cross sections;   the orifices for the passage of gas have passage cross sections that are defined by internal diameters of the two longitudinal ends of the body.       
 
         [0029]    The present disclosure also relates to a gas-powered fixing tool, characterized in that it comprises at least one combustion chamber as described hereinabove. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    The present disclosure will be better understood and further details, features and advantages of the present disclosure will become more clearly apparent from reading the description which follows, given by way of nonlimiting example, and by referring to the attached drawings. 
           [0031]      FIG. 1  is a schematic partial view in axial section of a combustion chamber of a gas-powered fixing tool of the present disclosure, this chamber comprising a valve including a mobile body in an open position. 
           [0032]      FIG. 2  is a view corresponding to  FIG. 1  and in which the mobile body is in a closed position. 
           [0033]      FIG. 3  is another partial schematic view in axial section of the combustion chamber of  FIG. 1 . 
           [0034]      FIG. 4  is a view corresponding to  FIG. 1  and illustrates an alternative embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0035]    The fixing tool  10  (sometimes called the “tool” for brevity) is partially visible in the drawings. This tool comprises a casing  12  in which there is an internal combustion engine with a combustion chamber  14  (or a precombustion chamber and a combustion chamber) that is intended to contain a mixture of air and fuel the ignition of which propels a piston intended to drive a fixing element taken from a feed magazine, the fixing element being intended to be anchored in a support material, at the outlet of a nail guide extending at the front of the casing. All of these components of gas-powered fixing tools are perfectly well known to those skilled in the art and have therefore not all been depicted in the drawings. 
         [0036]    The supply of fuel to the combustion chamber  14  of the motor is effected via an injection member from a fuel gas cartridge. 
         [0037]    The casing  12  of the tool comprises a handgrip  16  for holding and handling the tool. The handgrip  16  is also used for firing, by means of an actuating trigger  18  mounted thereon. 
         [0038]    In the example depicted, the combustion chamber  14  comprises an intake valve  20  for the fuel gas delivered by the cartridge. This valve  20  is hollow or, more precisely, its mobile body  22  is hollow. 
         [0039]    The mobile body  22  is mobile between a position in which an intake orifice  24  is open, which position is depicted in  FIG. 1 , and a position in which the intake orifice  24  is closed, which position is depicted in  FIG. 2 . 
         [0040]    The mobile body  22  is able to move in a fixed casing  26  of the combustion chamber, which in this instance is formed by an assembly of parts or elements which will be described in detail in what follows. 
         [0041]    The body  22  has a tubular elongate form and comprises an internal bore  28  emerging at the two longitudinal ends  22   a ,  22   b  of the body to form, respectively, two orifices  30   a ,  30   b  for the longitudinal passage of gas. 
         [0042]    The body  22  has a generally cylindrical form in the example depicted. It comprises an outer cylindrical surface and has an outside diameter that is substantially constant. At its end  22   a  it comprises an outer annular groove in which there is mounted a seal  30  intended to collaborate with the casing  26 . It also comprises, substantially in its middle, an outer annular groove  31  in which one end of a finger  34  actuated by the trigger  18  is intended to engage. 
         [0043]    The end  22   a  of the body comprises an inner annular flange defining the orifice  30   a , which is a gas exhaust orifice. The end  22   b  of the body comprises an inner annular flange defining the orifice  30   b , which is a gas intake orifice. These flanges have substantially the same inside diameter. 
         [0044]    Although this is not in any way limiting, the bore  28  of the body has a restriction  33  of its passage cross section substantially in the middle of the body. This restriction  33  defines an inside diameter substantially equal to that of the aforementioned flanges. 
         [0045]    The restriction  33  and the groove  31  are situated substantially in the same plane P 1  transverse to the longitudinal axis X of the mobile body  22 . The seal  30  is situated in another transverse plane P 2  passing substantially through the orifice  30   a  of the body  22 . 
         [0046]    The casing  26  of the chamber comprises a tubular cylindrical element  32  in which the body  22  is housed and can slide. This element  32  has an elongate form with longitudinal axis X. 
         [0047]    The element  32  comprises an internal cylindrical surface collaborating with the seal  30  borne by the body  22 . 
         [0048]    In the example depicted, the element  32  comprises an orifice  35  that is radial (with respect to the axis X) and through which one end of an igniter plug  36  can pass to initiate combustion of the air-fuel mixture in the chamber. This plug  36  may be of the piezoelectric type and be actuated by the aforementioned finger  34  when the user operates the trigger  18 . 
         [0049]    The element  32  further comprises a radial through-slot  38  which has a form that is elongate along the axis X. The finger  34  comprises an end which passes through the slot  38  and is engaged in the groove  31  of the body. When the trigger  18  is actuated, the finger  34  is moved translationally along the axis X, and its end slides in the slot to drive the mobile body  22  into the casing  26  of the chamber. It will thus be appreciated that the length of the slot (the dimension along the axis X) is dependent on the expected travel of the body  22 . Advantageously, and as may be seen in the drawings, whatever the position of the body  22  along the axis, the slot  38  is covered and therefore closed off by the body  22 . 
         [0050]    The casing  26  comprises another element  40  mounted at one longitudinal end of the element  32 . This other element  40  comprises an internal bore  42  communicating with the internal housing of the element  32 . 
         [0051]    The bore  42  has a generally cylindrical form with axis X of revolution and is therefore coaxial with the internal housing of the element  32 . This bore  42  in certain embodiments has an inside diameter substantially equal to the inside diameter of this internal housing. 
         [0052]    The body  22  of the valve is able to slide in the bore  42 . 
         [0053]    The element  40  comprises a radial orifice emerging into the bore  42  and forming the aforementioned intake orifice  24 . This orifice  24  communicates with the aforementioned injection member to supply the combustion chamber with fuel. 
         [0054]    As may be seen in the drawings, when the body  22  is in its open position ( FIG. 1 ), the orifice  24  is left uncovered, enabling fuel to enter the bore  42  then pass longitudinally along the body  22  (cf. arrows). When the body  22  is in its closed position ( FIG. 2 ), the orifice  24  is hermetically closed off by the body  22 . 
         [0055]    It will thus be appreciated that the travel of the body, between its two extreme positions, is greater than the diameter of the orifice  24 , so that the body does not impede the passage of gas through the orifice  24  in the open position (in this instance the high position), and so that the body completely closes off the orifice in the closed position (in this instance the low position). 
         [0056]    The casing  26  further comprises another element  46  of generally cylindrical form aligned with the axis X. This element  46  is arranged at one end of the chamber and is intended to be partially housed in the bore of the body  22  when the latter is in the closed position ( FIG. 2 ). 
         [0057]    This element  46  at its outer periphery comprises an outer annular groove to house a seal  48  intended to collaborate with the flange of the end  30   b  of the body  22 . The seal  48  is situated in another transverse plane P 3 . 
         [0058]    The element  46  at its opposite longitudinal end to the body  22  comprises an outer annular flange  50  the outside diameter of which is here substantially identical to that of the body  22 . A return spring  44 , in this instance a helical spring, is mounted around the element  46  and comprises a first end bearing against the flange  50  and an opposite end bearing against the end  30   b  of the body in order to bias it into its open position. 
         [0059]    As can be seen in the drawings, the element  46  may comprise an internal axial bore  52  for the passage of an igniter plug (not depicted) in the place of the aforementioned one. The bore  52  here is aligned with the axis X. 
         [0060]    The end  30   a  of the body is connected to a cylindrical rod  54  of longitudinal axis X. This rod  54  has a diameter smaller than the inside diameter of the body. Its diameter is in certain embodiments comprised between 0.1 and 0.3 times the inside diameter of the body, and is, for example, from 0.15-0.16 times the inside diameter of the body. 
         [0061]    The rod  54  has a length that is markedly greater than that of the body  22  and extends into the element  32  of the casing  26 . Its longitudinal end situated on the body side is connected to the end  30   a  of the body by two, three, or more legs  56 . These legs  56  are uniformly distributed about the axis X and are therefore diametrically opposed when there are two of them. The legs  56  are intended to have the gas passing between them and are in certain embodiments profiled in order to limit operational pressure drops (arrows). 
         [0062]    As can be seen in  FIG. 3 , the opposite end of the rod  54  to the body may be connected to a valve shutter  58  and/or to another valve  60 , such as an exhaust valve. 
         [0063]    The valve shutter  58  for example comprises a disc  62  through which the rod  54  passes and which is secured thereto. The disc  62  is intended to collaborate with an annular seat  64  of the element  32  of the casing.  FIG. 3  illustrates the valve shutter  58  in the open position, the disc  62  being away from its seat. This scenario corresponds to the open or upper position of the body  22  ( FIG. 1 ). In the closed or lower position of the body  22 , the disc  62  collaborates in a sealed manner with the seat  64 . The seat  64  may define an orifice for the passage of gas from the combustion chamber  14 , which is a precombustion chamber, to another combustion chamber  66 . 
         [0064]    In the example depicted, the valve  60  comprises a mobile body  68  in the form of a disc or piston which at its external periphery bears a seal  70  intended to collaborate with an internal cylindrical surface of an orifice  72  for exhausting combustion gases from the combustion chamber  66 . 
         [0065]    It is important to note that this valve  60  could be equipped with a mobile body similar to that  22  of the other valve. 
         [0066]    The fixing tool  10  and the combustion chamber  14 ,  66  may operate as follows. In general, the placing of one end of the tool on the support material into which a fixing element is to be affixed enables a quantity of fuel to be released from the cartridge, this fuel being conveyed from the cartridge to the intake orifice  24  of the element  40 . The fuel enters the precombustion chamber  14  because of the opening of the valve (mobile body  22  in the upper or open position as shown in  FIG. 2 ). The user generally has a few seconds to spare before the fuel is diffused into the atmosphere and in which to actuate the trigger  18 . When the trigger  18  is actuated, the finger  34  is moved, causing both the body  22  to move from its open position into its closed position, and the generation of a spark by the igniter plug  36 . This spark brings about precombustion of the air-fuel mixture in the combustion chamber  14 , which causes an increase in pressure in the chamber  14 , which means inside the element  32 . When this pressure overtakes a certain threshold, the valve shutter  58  opens and enables the mixture to pass into the combustion chamber, the pressure in which increases. Shortly afterwards, the flame passes in turn through the valve shutter  58  and ignites the combustion chamber  66  and causes the piston to move and a fixing element to be ejected into the support material. After the piston has returned to its rest position, the valve  60  opens to expel the combustion gases through the exhaust orifice  72 . 
         [0067]      FIG. 4  illustrates an alternative form of embodiment of the present disclosure in which the rod  54  is replaced by a sleeve  54 ′ having an inside diameter substantially identical to the inside diameter of the bore  28  of the body  22 , or rectilinear rods extending over a circumference of diameter substantially identical to that of the body.