Abstract:
In a device (P) for delivering a gas out of a pressure chamber ( 5 ), in particular into a container ( 17 ) for dispensing a sealant ( 15 ) from said container into a tire ( 18 ) of a vehicle and/or for inflating the tire, wherein a plunger ( 4 ) is arranged to be oscillatingly movable in the pressure chamber, a gasket ( 20 ) is associated with the plunger and changes the distance thereof from a pressure chamber wall ( 28 ) when there is a change in the direction of movement of the plunger.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a device for delivering a gas from a pressure chamber into a container, in particular, for dispensing a sealant from this container into a tire of a vehicle and/or for inflating the tire, wherein a piston is arranged in the pressure chamber such that it can move in an oscillatory fashion. 
         [0002]    DE 10 2004 042 911 A1 has disclosed a device for delivering a gas from a pressure chamber into a container, in particular, for dispensing a sealant from this container into a tire of a vehicle and for inflating the tire. A compressor can be connected to the sealant container disclosed in said document. This compressor may also be embodied as a membrane compressor, which compresses air that is present in the sealing container in order to press sealant out of the sealant container. A disadvantage of this embodiment is that the air is heated as a result of the compression, but it cannot be correspondingly cooled or discharged. This overheating may lead to a failure of the membrane pump. Furthermore, it is also disadvantageous that the membrane-pump device and the sealing container substantially have an integral design and the former cannot easily be replaced. By way of example, it is difficult to combine the membrane device with a new sealing container when the sealing container is empty; this, in particular, is not particularly environmentally friendly. 
         [0003]    It is an object of the invention to develop a device for delivering a gas, which device is environmentally friendly, prevents the delivery device from overheating, has a simple design, and can be kept small. 
       SUMMARY OF THE INVENTION 
       [0004]    The object of the invention is achieved by a device for delivering a gas from a pressure chamber into a container, in particular, for dispensing a sealant from this container into a tire of a vehicle and/or for inflating the tire, wherein a piston is arranged in the pressure chamber such that it can move in an oscillatory fashion, characterized in that a gasket is associated with the piston, which gasket changes the distance thereof from a pressure-chamber wall when the movement direction of the piston changes. 
         [0005]    A change in the sealing properties of the gasket as a result of the piston moving in a to-and-fro direction allows sufficient air to be able to be delivered to the piston for compressing and for cooling the piston. 
         [0006]    Furthermore, the object disclosed above is achieved by a device for delivering a gas, wherein a gear element is associated with the piston, which gear element converts a rotational motion of a drive shaft of a drive into an oscillatory motion. 
         [0007]    The simple yet nevertheless effective embodiment of the gear element, which acts as a rotation transducer, allows the piston to be driven in a simple yet nevertheless effective fashion such that it can move, to-and-fro, in an oscillatory fashion. This does not require a complicated design, but rather a few components that can easily be combined with various drive elements. By way of example, the drive can be an electric motor, but other drives are also feasible. All that is essential is that the drive element has a drive shaft to which the gear element can be attached in a rotationally fixed fashion. 
         [0008]    In a preferred embodiment, the gasket is a sealing lip, which can rest against a pressure cylinder in a sealing fashion. However, other types of gasket are also feasible; all that is essential here is that the gasket has such a flexible and elastic design that it seals during an upward motion of the piston and can release the sealing effect during a downward motion of the piston such that air can stream past the piston. 
         [0009]    In a preferred embodiment, the gasket and the piston have an integral design; that is to say the piston and the gasket are made from the same material, the material having to provide appropriate elasticity such that the gasket can move to a sufficient extent but the piston also having sufficient stability such that an oscillatory motion, exerted by the gear means, is not damped by the piston but transmitted accordingly. 
         [0010]    The piston may be produced from rubber. However, other plastics and materials that provide both sufficient flexibility and stability are also feasible such that the gasket is able to fulfill its sealing and releasing function and the piston can correspondingly transmit the oscillatory motion of a gear element. 
         [0011]    Moreover, it is also essential that the gasket forms a boundary edge that extends to the pressure chamber of the piston such that sufficient tightness is provided during the compression stage of the piston. In this case, various shapes are feasible; all that is essential is that the boundary edge can establish a reversible, airtight connection to the pressure chamber such that the air is compressed during the upward motion of the piston. In this case, it is essential that the boundary edge circumscribes a greater diameter than the diameter of the piston body per se. This is because the piston body should have play with respect to the inner peripheral wall of the pressure cylinder such that air can accordingly be suctioned-in and routed to the gasket. 
         [0012]    Furthermore, it is essential that recesses are provided on the gasket and delimit the latter such that the suctioning-in and compression function of the piston is ensured. These recesses provide the flexibility of the gasket such that the gasket can change its sealing effect depending on the movement direction of the piston. The shape of the recess is unimportant. However, all that needs to be ensured is that the recess gives the gasket sufficient flexibility and that enough air can collect there, as a result of which the position of the gasket can be changed. 
         [0013]    Furthermore, it is essential that a further recess is formed in the lateral peripheral wall of the piston below the gasket because this recess has the function of collecting air therein during the downward motion of the piston when new air is suctioned-in. This air then presses the gasket away from the pressure-chamber side wall of the pressure cylinder, and so the suctioned-in air can flow around the piston body, cool the latter, and collect in front of the piston end face of the piston. 
         [0014]    The design of the aforementioned recesses is unimportant. All that is essential in this case is that the suctioned-in air ensures the function of pressing-away or pressing-on. 
         [0015]    In a preferred embodiment the cross sections of the recesses are substantially drop- or U-shaped channels, which are formed, continuously and substantially annularly, in the piston-end-surface surface or on the pressure-chamber side wall of the piston. 
         [0016]    The recesses toward the gasket preferably have a smaller gradient, with the channels on the side facing away from the gasket having a larger curvature/gradient such that a drop-shaped channel is formed. Air can collect in this drop-shaped channel, which is then pressed against the gasket. 
         [0017]    In a preferred embodiment, the lip seal tapers toward the boundary edge thereof, preferably such that a substantially V-shaped boundary region is formed. 
         [0018]    However, other boundary-edge shapes are also feasible as long as it is ensured that the boundary edge rests tightly against the pressure-chamber side wall of the pressure cylinder and, in accordance with the motion, acts in a sealing or air-permeable fashion. 
         [0019]    In a further exemplary embodiment of the invention, the gasket is embodied as a gasket ring. This results in the advantage that the gasket ring can be replaced in a simple fashion in the case of wear-and-tear. 
         [0020]    The piston preferably has at least one conical surface. It is particularly preferred if the conical surface is provided on a groove in the piston. It is particularly preferred if the groove is provided over the entire circumference of the piston in an upper region. The gasket ring is expediently arranged such that, in the case of a stroke of the piston, the gasket ring runs outward along the conical surface until it rests against the pressure-chamber wall. This advantageously seals the pressure chamber. The ring gasket and the conical surface are preferably arranged such that the gasket ring rests against the pressure-chamber wall during an upward motion. During a downward motion, when gas, preferably air, should be suctioned into the pressure chamber, the gasket ring is situated in an inner region of the groove. 
         [0021]    The device according to the invention can be used in a versatile fashion. Between 10 and 20 000 strokes per minute are preferably possible. It is even more preferable for the device according to the invention to be able to carry out between 20 and 40 000 strokes per minute. This is brought about by a very high piston speed. By way of example, the cam can be operated at 167 revolutions per second. This corresponds to 334 strokes per second and a piston speed of 2.34 m/s. 
         [0022]    The gasket ring preferably also lightly rests against the pressure-chamber wall in the inner position of said gasket ring, but here it does not yet perform a sealing function. As a result of frictional forces, this supports the ring gasket in assuming its sealing position in the case of fast strokes. 
         [0023]    At least one radial channel is expediently provided on the piston. The at least one radial channel is preferably provided on a lower surface or inner side of the groove. A medium, preferably air, advantageously flows over the radial channels and past the gasket ring during the suctioning-in stroke. 
         [0024]    Advantageously, the piston from this exemplary embodiment does not become hot during operation. The piston preferably has a self-lubricating and maintenance-free design. 
         [0025]    Furthermore, in a preferred embodiment, a force-storage element in the form of a compression spring is arranged between the piston end face of the piston and the cover wall of the pressure cylinder. The compression spring is preferably made of plastic. However, other force-storage elements, such as elastic rubber plugs, are also feasible. All that is essential in this case is that the force-storage element provides sufficient force for the piston to be pressed sufficiently strongly against the gear element of the drive so that there is constant contact between the piston underside and the gear element. 
         [0026]    In a preferred embodiment, the gear element is a double cam, which has two projections such that said double cam has a substantially elliptical cross section. However, other gear-element shapes are also feasible. By way of example, the gear element can also be a cam with only one projection. Furthermore, gear elements with three projections are also feasible. All that is essential here is that the rotational motion of the drive shaft is converted into an oscillatory motion by the gear element. 
         [0027]    In the preferred embodiment, the drive is an electric motor. However, other drive elements are also feasible. All that is essential here is that the drive shaft of the drive provides a rotational motion. 
         [0028]    In a preferred exemplary embodiment the components of the device are made from plastic. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    Further advantages, features, and details of the invention emerge from the following description of a preferred embodiment, and from the drawing, in which: 
           [0030]      FIG. 1  shows a perspective partial sectional view of a device according to the invention for delivering a gas from a pressure chamber; 
           [0031]      FIG. 2  shows a sectional view of the device from  FIG. 1  during an application; 
           [0032]      FIG. 3  shows a schematic sectional illustration of a further exemplary embodiment of a piston of a device for delivering a gas from a pressure chamber during a downward motion; and 
           [0033]      FIG. 4  shows a schematic sectional illustration of the further exemplary embodiment of a piston of a device for delivering a gas from a pressure chamber according to  FIG. 3 , during an upward motion. 
       
    
    
     DETAILED DESCRIPTION 
       [0034]      FIG. 1  shows that the device P for delivering a gas from a pressure chamber  5  has a drive  1  with a drive shaft  2 , to which a gear element  3  has been attached in a rotationally fixed fashion. The drive  1  is an electric motor in the preferred embodiment. 
         [0035]    As shown in  FIG. 1 , the gear element  3  is a double cam  3  with a first projection  3 . 1  and a second projection  3 . 2 . The double cam  3  has been attached to the drive shaft  2  such that the two projections  3 . 1  and  3 . 2  protrude from the drive shaft in a substantially mirror-symmetric fashion. The elliptic shape of the double cam  3  converts the rotational motion of the drive shaft  2  into an oscillatory motion. The oscillatory motion brings about upward and downward motion of a piston  4 , which is mounted such that it can move to-and-fro in a pressure chamber  5  (see  FIG. 2 ). 
         [0036]    A force-storage element  6  holds the piston  4  against the gear element  3  under pretension such that the piston is in constant contact with the gear element  3 . 
         [0037]    In a preferred embodiment, the force-storage element  6  is a helical compression spring that, on the one hand, is inserted into and guided by a pocket  7  in the piston  4  and, on the other hand, is braced against an upper cover wall  29  of the pressure chamber  5 . 
         [0038]    The pressure chamber  5  is defined by a pressure cylinder  25 , which comprises the pressure-chamber cover wall  29 , which covers the pressure chamber  5  toward the top, and a pressure-chamber side wall  28 , which adjoins the pressure-chamber cover wall  29  in a substantially perpendicular fashion, surrounds the pressure chamber  5  in a cylindrical fashion, and substantially almost completely surrounds the piston laterally in the retracted position thereof, as can be identified in  FIG. 2  for example. 
         [0039]    Furthermore, an outlet  9  is formed in the pressure-chamber cover wall  29  of the pressure cylinder  5 , which outlet is formed substantially concentrically with the longitudinal center of the pocket  7 . The outlet  9  should let the air that was compressed by the piston  4  escape when a predetermined pressure has been built up. To this end, provision is made for a non-return valve  10 , which is housed in a valve housing  11  and seals the outlet  9  until the predetermined pressure has been built up in the pressure chamber  5  by compressing the air with the piston  4 . This pressure is also important to the sealing function of the piston  4 . The non-return valve has a valve flap  12 , which is guided in the valve housing  11  and has a pin  13  arranged in the center of said flap; a force-storage element  14  is plugged onto said pin and holds the valve flap under pretension against the outlet  9 . In the illustrated embodiment, the force-storage element  14  is a helical compression spring. 
         [0040]    The valve housing is adjoined by a tube-line connector  30 , onto which a tube line  16 , which is only illustrated schematically in  FIG. 2 , can be plugged-on in an airtight fashion such that gas that was compressed in the pressure chamber  5  can be delivered. Either the tube line  16  can be directly connected to the valve (without reference sign) of a tire  18  to be inflated or a sealant container  17  can also be connected to the tube line  16  such that, firstly, a sealant  15  and, then, a pumped gas can be pumped into the tire  18  by means of the device P. Then additionally an only schematically illustrated connection line  19  is connected to the valve  20  of the tire  18  in an airtight fashion. 
         [0041]    The piston is substantially moved between two extreme positions: a retracted position and an extended position. The retracted position shown in  FIG. 1  is assumed by the piston  4  when the first or second projection  3 . 1 / 3 . 2  of the gear element  3  is in the position illustrated in  FIGS. 1 and 2 . The extended position is assumed by the piston  4  when the flat section  3 . 3  of the gear element  3  is in contact with the piston. Air is suctioned-in and the piston  4  is cooled when the piston  4  is moved from the retracted position to the extended position. 
         [0042]    The suctioned-in air is compressed when the piston is moved from the extended position into the retracted position. In the process, a gasket  20 , which is provided on the piston  4 , plays an essential role. 
         [0043]    Said gasket is delimited by a first recess  21  and a second recess  22 . In the preferred embodiment, the gasket  20 , as illustrated, is a lip seal  20  that tapers toward the pressure-chamber side wall  28  of the pressure cylinder  5  and rests against the pressure-chamber side wall  28 . The first and second recesses  21 ,  22  serve for allowing air to be respectively collected therein and, in accordance with the movement direction of the piston  4 , either for pressing the lip seal  20  securely against the pressure-chamber side wall  28  such that either air is compressed in front of the piston end face  26 , or for pressing the lip seal  20  away from the pressure-chamber side wall  28  such that air is suctioned-in front of the piston end face  20 . 
         [0044]    The first recess  21  is arranged on the piston end face of the piston  4 , concentrically with respect to the center of the pocket  7 , which first recess has a substantially annular design and a substantially channel-shaped cross section, wherein the wall section of the channel  21  facing the lip seal  20  has a smaller gradient or curvature than the channel section extending in the direction of the pocket  7 . As a result, the first recess  21  has a drop-like form, which supports the collection of air when the piston  4  is moved toward the retracted position. 
         [0045]    The collection of air in the first recess  21  is intensified during the upward motion and thereby presses the lip seal against the pressure-chamber side wall  28 , as a result of which the piston automatically seals against the pressure cylinder  25 . The fact that pressure can increase there is supported by the non-return valve  10 , which only opens when a predetermined pressure is present; this can be set by the force-storage element  14  of the non-return valve  10 . When the non-return valve  10  opens, the compressed air is delivered to a tire  18 , for example, via the tube line  16 . 
         [0046]    Furthermore, a second recess  22  is formed in the pressure-chamber side wall of the piston  4 , which second recess has a similar cross section to the first recess but merely is slightly larger. The second recess  22  circumscribes the peripheral lateral surface of the piston  4 . This second recess  22  serves to allow the air to flow through and along an interspace  23 , which is defined by the peripheral lateral surface of the piston  4  and the inner peripheral wall surface of the pressure-chamber side wall  28 , and to collect in the recess  22  with the drop-shaped cross section when the piston is moved in a downward motion to the extended position by means of the force-storage element  6 , as a result of which the lip seal  20  is pressed away from the pressure-chamber side wall  28  and so the air can flow around the lip seal  20  and collect in front of the piston end face of the piston  4 . This flowing around the lip seal at the same time cools the piston  4 ; this affords the possibility of preventing the entire device from overheating as a result of the compression procedure. 
         [0047]    The functionality of the device for delivering a gas is the following:
   Should a tire  18  no longer contain sufficient pressure as a result of a leak in the tubing, the device P for delivering a gas may be used to rebuild pressure, according to regulations, in said tire  18 .   
 
         [0049]    Furthermore, should a hole in the tubing of the tire  18  be the reason for the loss of pressure in the tire  18 , a sealant  15 , which is contained in the sealant container  17 , can be delivered to the tire before the latter is inflated with air. To this end, a tube line  16  is attached to the base end of the sealant container  17 , which has an appropriate connection opening for this purpose. If the drive  1  is now put into motion, the drive shaft  2  drives the gear element  3 , which converts the rotational motion of the drive shaft  2  into an oscillatory motion and moves the piston  4  up and down in the pressure cylinder by virtue of the double-cam-shaped form of said gear element. In the process, the compression spring  6  also plays an essential role because it presses the piston back into the initial position thereof. This to-and-fro motion of the piston, and the embodiment of the lip seal on the piston end face of the piston with the corresponding recesses  21  and  22 , leads to air being delivered to the sealant container  17  and the sealant found in the latter being delivered to the leaky tire  18 . The sealant is distributed in the defective tubing as a result of the delivered gas and seals leaks that are present. After the tubing is sealed, the tubing of the tire  18  is inflated by means of the device P for delivering a gas. 
         [0050]      FIGS. 3 and 4  disclose a further exemplary embodiment of a device for delivering a gas. This device has an analogous design to the device of the exemplary embodiment described above, but has a different piston  27 . 1  that is used in the pressure cylinder  25 . 
         [0051]    A gasket ring  33  is provided on the piston  27 . 1  as a seal. In order to hold the gasket ring  33 , the piston  27 . 2  has a groove  31 . This groove  31  is situated in an upper region of the piston  27 . 1  and extends over the entire circumference of the lateral surface of the piston  27 . 1 . 
         [0052]    An inner side of the groove  31  is embodied as a conical surface  32 . A radial channel  34  is provided on the opposite inner side or lower surface of the groove. A plurality of radial channels can also be provided on an inner side of the groove in a further exemplary embodiment of the invention. 
         [0053]    In principle, the functionality of this exemplary embodiment of the invention is analogous to the functionality of the exemplary embodiment described above. In the following text, it is only the functionality of the seal that is discussed in any more detail. 
         [0054]    In  FIG. 3 , the piston  27 . 1  of the device for delivering a gas is illustrated during a downward motion in the direction of the arrow K. In the process, the gasket ring  33  is situated in the groove  31  such that gas can be suctioned into the pressure chamber  5 . In the illustrated exemplary embodiment, the gasket ring  33  does not touch the pressure-chamber side wall  28  of the pressure cylinder  25 . 
         [0055]    In a further exemplary embodiment of the invention (not illustrated), the gasket ring can also be arranged such that although it rests against the pressure-chamber side wall of the pressure cylinder during the motion illustrated in  FIG. 3 , it does not exert a sealing function. Then gas can nevertheless be suctioned into the pressure chamber. In particular, this takes place via the channels. 
         [0056]    At the start of the very quick upward motion of the piston  27 . 1  in the direction of the arrow G, or just thereafter, as illustrated in  FIG. 4 , the gasket ring  33  changes the position thereof and widens such that it closes-off a circumferential gap  35  between the pressure cylinder and the piston  27 . 1 . The gas in the pressure chamber  5  is then pressed through the outlet  9 . The widening is supported by virtue of the fact that the gasket ring runs down the conical surface  32  because it cannot follow the speed of the piston as a result of the inertia of said gasket ring and/or because it slightly rests against the inner wall of the pressure cylinder  25  and is subjected to friction.