Patent Publication Number: US-2012037455-A1

Title: Lubricant applicator for a wheel of a trackbound vehicle

Description:
TECHNICAL AREA 
     The present invention concerns a lubricant applicator for a wheel of a trackbound vehicle, which applicator comprises an applicator cylinder for a lubricant stick. 
     The present invention also concerns a method of lubricating a wheel of a trackbound vehicle with the help of a lubricant applicator which comprises an applicator cylinder for a lubricant stick. 
     TECHNICAL BACKGROUND 
     A wheel intended for a railway carriage, a railway engine, a railcar, or some other trackbound vehicle, has a tread surface, which is intended for rolling against the upper part of that rail over which the wheel is to roll, and a flange, which is responsible for the guiding against the rail, such that the trackbound vehicle does not leave the rails. 
     The tread surface of a wheel of the above described type rolls, with very low friction, against the upper side of the rail. The flange of a wheel of the type described above will, however, come into sliding contact with the sides of the rail. This sliding contact causes friction and an unwanted wear on the both the wheel and the rail. 
     U.S. Pat. No. 5,054,582 describes a lubricant applicator which is arranged to press a solid lubricant stick against that position on a wheel where a tread surface and a flange are joined in order to decrease the friction described hereinbefore. 
     A problem with the lubricant applicator which is disclosed in U.S. Pat. No. 5,054,582, is that the lubricant stick easily gets stuck in its holder and is not transported forward in the desired manner. 
     SUMMARY OF THE INVENTION 
     A purpose of the present invention is to provide a lubricant applicator for application of lubricant on a flange which is comprised in a wheel for a trackbound vehicle, which lubricant applicator requires little maintenance. 
     This purpose is achieved by means of a lubricant applicator for a wheel of a trackbound vehicle, which applicator comprises an applicator cylinder for a lubricant stick, characterized in that the lubricant applicator further comprises 
     a piston, which is arranged to run in the applicator cylinder and to press the lubricant stick against said wheel, and 
     a space inside the applicator cylinder which is arranged to receive a pressurized fluid for pressing the piston against the lubricant stick. 
     An advantage of this lubricant applicator is that a reliable lubrication is ensured. A further advantage is that the pressure with which the stick is pressed against the wheel is substantially independent of how worn the stick is. 
     According to a preferred embodiment the applicator cylinder has a circular cross-section. An advantage of this embodiment is that efficient sealings between the applicator cylinder and lubricant stick can be easily achieved, with the help of, for example, O-rings. 
     According to a preferred embodiment a control device is arranged to receive at least one signal from a sensor, which senses at least one operating parameter of the trackbound vehicle, and to control the pressure of the pressurized fluid supplied to the space depending on this signal. An advantage of this embodiment is that it becomes possible to apply lubricant depending on the present need for lubricant. In for example curves more lubricant can be applied, and less lubricant may be applied at straight stretches. This reduces the average consumption of lubricant. 
     According to a preferred embodiment both the lubricant stick and the applicator cylinder are formed from electrically conductive material and are in electric contact with each other, wherein currents that pass from a rail to said wheel can be conducted via the lubricant stick and the applicator cylinder further to the trackbound vehicle. An advantage of this embodiment is that the electric load on bearings of the wheels, caused by current being conducted through these, can be reduced, with reduced maintenance costs as a consequence. 
     According to a preferred embodiment the lubricant stick is formed from a material comprising graphite. Graphite has the advantage that it both has lubrication qualities and is also electrically conductive. 
     According to one embodiment a part of the lubricant stick forms that piston which runs in the applicator cylinder. An advantage of this embodiment is that very few parts are required, since the lubricant stick will both work as stick, at its end being directed towards the wheel, and as piston, at its end being directed towards said space. 
     According to another preferred embodiment a separate piston is arranged to run in the applicator cylinder and to be pressed against the lubricant stick. An advantage of this embodiment is that the safety to leakage of pressurized fluid is increased, which is particularly important if pressurized fluids that should not leak into the surroundings, such as hydraulic oil, are used. 
     According to a preferred embodiment the applicator cylinder is releasably attached to a bracket which is mounted on the trackbound vehicle. An advantage of this embodiment is that exchange and maintenance of the lubricant stick becomes very neat. 
     A further purpose of the present invention is to provide an efficient and reliable method of applying lubricant to a wheel of a trackbound vehicle. 
     This purpose is achieved by means of a method of lubricating a wheel of a trackbound vehicle with the help of a lubricant applicator which comprises an applicator cylinder for a lubricant stick, wherein the lubricant applicator further comprises a piston, which is arranged to run in the applicator cylinder and to press the lubricant stick against said wheel, and a space inside the applicator cylinder which is arranged to receive a pressurized fluid for pressing the piston against the lubricant stick, wherein at least one operating parameter which describes the present operating condition of the trackbound vehicle is measured, and 
     that the pressure in said space is adapted to provide a desired lubrication of said wheel with regard to said present operating condition. 
     An advantage of this method is that an efficient and controlled lubrication of the wheel is achieved. 
     Preferably said at least one operating parameter comprises at least one of the present curve position of the trackbound vehicle and the present speed of the trackbound vehicle. The curve position, that is, whether the vehicle is in a curve or not, and how tight such curve is, and the speed are two of those parameters that have the largest influence on the need for lubrication. 
     Further advantages and features of the invention will become apparent from the below description and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will hereafter be described with the help of examples of embodiments and with reference to the enclosed drawings. 
         FIG. 1  is a side view and shows schematically a lubricant applicator for application of lubricant on a flange which is comprised in a wheel of a trackbound vehicle. 
         FIG. 2   a  is a cross-section and shows a lubricant holder forming part of the lubricant applicator as seen from the side thereof. 
         FIG. 2   b  is a cross-section and shows the lubricant holder illustrated in  FIG. 2   a  as seen in the cross-section IIb-IIb. 
         FIG. 3  is an enlarged view and illustrates the portion III illustrated in  FIG. 2   a.    
         FIG. 4  is a side view, and shows schematically a control system comprised in the lubricant applicator. 
         FIG. 5  is a cross-section and shows a lubricant holder according to an alternative embodiment, as seen from the side thereof. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION 
       FIG. 1  illustrates a lubricant applicator  1  in accordance with one embodiment of the present invention. The lubricant applicator  1  has a lubricant holder  2  and a control system  4 , both of which are to be described in more detail hereinafter. The lubricant applicator  1  is arranged for pressing a solid lubricant stick  6  against a wheel  8 , the outer portions of which are illustrated in  FIG. 1 , of a trackbound vehicle, such as a railway engine, a railway carriage, a railcar, a tram, etc,. 
     The wheel  8  has a tread surface  10  which is arranged for rolling against the upper side of a rail  12 . The wheel  8  also has a flange  14  which guides the position of the wheel  8  in relation to rail  12 . The lubricant holder  2  of the lubricant applicator  1  is mounted on the trackbound vehicle  9 , schematically illustrated in  FIG. 1 , and presses the stick  6  against the wheel  8  in that position on the wheel  8  where the tread surface  10  passes on to the flange  14 , a position which can be called the root  16  of the flange  14 , for the purpose of reducing the friction between the flange  14  and the rail  12 . 
     The lubricant holder  2  will now be described in more detail with reference to  FIG. 2   a  and  FIG. 2   b .  FIG. 2   a  illustrates the lubricant holder  2  in more detail, as seen in cross-section and from the side thereof.  FIG. 2   b  illustrates the lubricant holder  2  as seen in a cross-section IIb-IIb illustrated in  FIG. 2   a . The lubricant holder  2  has a bracket  20 , which is provided with two openings  22 . The openings  22  are intended for receiving bolts, not shown, for holding the bracket  20  on the  FIG. 1  schematically illustrated trackbound vehicle  9 . 
     The bracket  20  is provided with a shelf  24 , which is open in the middle. An applicator cylinder  26  abuts this shelf  24 , as is best illustrated in  FIG. 2   b . Two releasable cotters  28  hold the applicator cylinder  26  pressed against the shelf  24 . The lubricant stick  6  runs inside the applicator cylinder  26 . The applicator cylinder  26  as well as the lubricant stick  6  has preferably circular cross-section, as is best illustrated in  FIG. 2   b , but may also have another cross-section, such as a square cross-section, triangular cross-section, oval cross-section etc. 
     In its rear part  27 , the applicator cylinder  26  has, as is clear from  FIG. 2   a , a gable  30  and a connection opening  32  for connection of a pipe  34 . The gable  30  is provided with an all around running outer track  31  in which the rear cotter  28  can engage, which means that the applicator cylinder  26  is locked also in its longitudinal direction. The pipe  34  is intended for supply of pressurized fluid to the applicator cylinder  26 . This pressurized fluid may advantageously be pressurized air, but may also be hydraulic oil, nitrogen gas, water, or some other suitable fluid. 
     The rear part of the solid lubricant stick  6  is arranged for functioning as a piston  36  inside the applicator cylinder  26 . When a pressurized fluid, for example pressurized air, is supplied to the applicator cylinder  26  this fluid will, via the pipe  34  and the connection opening  32 , enter a cylinder space  37 , which is formed between the piston  36 , the gable  30  and the walls of the applicator cylinder  26 , and press the piston  36 , i.e. the lubricant stick  6 , against the root  16  of the flange  14  and provide the desired lubrication. Hence in this embodiment a part of the lubricant stick  6 , and rather its rear part, forms that piston  36  which under influence of the pressurized fluid in the space  37  presses the lubricant stick  6  against the wheel  8 . 
       FIG. 3  illustrates the portion III illustrated in  FIG. 2   a  in more detail. The applicator cylinder  26 , which is squeezed between the shelf  24  and cotter  28 , has at its front end  38  a sealing case  40 , which is attached to the front end  38  of the cylinder  26  by means of a threaded connection. The sealing case  40 , the interior cross-section of which is circular, has an internal track  42  in which a sealing  44  has been arranged. 
     The sealing  44  is suitably a circular sealing ring, such as a so-called O-ring, for example made of rubber material, and provides a sealing between the case  40  and the stick  6 . The sealing  44  has two purposes. One purpose is to provide a sealing between the stick  6  and the applicator cylinder  26  such that pressurized fluid which is supplied to the cylinder space  37  does not leak out there from. The other purpose is to provide a sealing such that dirt, for example dust, water, snow, etc, that whirl up around the wheel  8  cannot enter the interior of the applicator cylinder  26  and cause operating problems caused by the stick ( 6 ) not being able to slide in the desired manner inside the cylinder  26 . 
     The applicator cylinder  26  is, according to a preferred embodiment, formed from an electrically conductive material, such as a metal, for example steel. Furthermore the lubricant stick  6  is in accordance with this preferred embodiment also formed from an electrically conductive material. An example of such material which is both electrically conductive and has good lubricating qualities is graphite. According to this preferred embodiment electric current can be conducted from the rail  12  to the wheel  8 , further from the wheel  8  to the stick  6  and from there via the applicator cylinder  26  and the bracket  20  directly to the trackbound vehicle  9 . In this case the lubricant applicator  1  also works as a ground connection. An advantage of this is that electric current need not be conducted via bearings of the wheel  8 , or at least needs to be conducted via bearings of the wheel  8  to a limited extent, which reduces the risk of current damages to these bearings. Electric contact between the stick  6  and the applicator cylinder  26  normally arises by itself, since the stick  6  normally will be somewhat inclined inside the applicator cylinder  26 , such that there will be electric contact between the applicator cylinder  26  and the stick  6 . Sometimes it may be suitable to improve this electric contact by means of for example a contact ring  43  made from a conductive material. 
       FIG. 4  illustrates the control system  4  of the lubricant applicator  1  in more detail. A control device  46 , such as a computer, microprocessor, or similar, receives signals from a number of sensors describing the present operating conditions of that trackbound vehicle on which the lubricant applicator  1  is mounted. Among other things the control device  46  receives signals from a curve sensor  48 , which senses whether the trackbound vehicle turns, and in such case how much, or if it runs straight ahead. The control device  46  receives signals from the curve sensor  48  and calculates, based on these signals, the magnitude of the need for lubrication. 
     The friction between the flange  14  of the wheel  8  and the rail  12  is normally at its largest upon cornering, and thereby the need for lubrication is largest when the vehicle is in a curve. 
     The control device  46  sends signals to a control valve  50  which is arranged on the pipe  34 , which at one end is connected to the gable  30  of the applicator cylinder  26 . At its other end the pipe  34  is connected to a supply of pressurized fluid, not shown, for example the pipe  34  may be connected to a pressure tank for pressurized air. 
     When the control device  46  receives signals from the curve sensor  48  that the trackbound vehicle has entered a curve the control device  46  sends a signal to the control valve  50  that it should open. When the control valve  50  opens pressurized fluid, such as pressurized air, flows into the cylinder space  37  and exerts, thanks to the pressure that arises in the space  37 , a pressure against the piston  36 , i.e. against the stick  6 , which thereby will be pressed against the root  16  of the flange  14  and generate the lubrication that is needed in the curve. 
     When the control device  46  then receives signals from the curve sensor  48  that the trackbound vehicle has again entered a straight portion of the track the control valve  50  is closed again. The pressure in the space  37  decreases again. This can either occur gradually by the pressurized fluid slowly leaking out through the sealing  44 , illustrated in  FIG. 3 , or by the pressurized fluid being evacuated through a separate pipe  52 , which is provided with an evacuation valve  54  that is controlled by the control device  46 . When the pressure in the space  37  decreases again the force with which the stick  6  is pressed against the root  16  of the flange  14  will decrease, and thereby the lubrication also decreases. 
     Hence the control device  46  controls the supply of lubricant in such a manner that lubricant is supplied to the wheel  8  when it is needed, for example at cornering, but is not supplied when there is no need for lubricant, for example in straight stretches. The control device  46  can also be arranged to control the pressure gradually depending on how tight the present curve is. For example the control device  46  can be arranged to control the control valve  50  to supply a first pressure at moderately tight curves, and can be arranged to control the control valve  50  to supply a second pressure, which is higher than the first pressure, at very tight curves. Of course the control device  46  can also be arranged to continuously control the pressure in the space  37  depending on the signal from the curve sensor  48 , for example according to the principle of a PID regulator. The control device  46  can also be arranged to achieve a certain lubrication also at straight stretches, if that is desired, wherein this lubrication is normally smaller than the lubrication in cornering. 
     The control device  46  may also receive other signals, for example concerning the speed of the trackbound vehicle, the ambient temperature, etc, and allow these signals to influence the degree of opening of the control valve  50 . 
     As the lubricant stick  6  is consumed the space  37  will be larger. Thanks to the fact that the pressure of the fluid supplied to the space  37  is controlled to the same value at a certain operating condition, regardless of how long the stick  6  has been used, the pressure with which the stick  6  is pressed against the root  16  of the flange  14  will be the same, at the same setting of the control valve  50 , regardless of whether the stick  6  is almost new, or if the stick  6  is almost worn out. 
     When the lubricant stick  6  is worn out it can easily be changed. This is made by releasing the pipe  34  shown in  FIG. 2   a  from the gable  30 . Then the cotters  28  illustrated in  FIGS. 2   a  and  2   b  are released and the applicator cylinder  26  is removed from the shelf  24  of the bracket  20 . Then a new applicator cylinder  26 , which has a pre-mounted lubricant stick  6 , is mounted in the bracket  20  with the help of the cotters  28 . The old applicator cylinder  26  is sent away for maintenance, check and mounting of a new lubricant stick  6 . The wear part which is changed is, hence, a complete unit which comprises applicator cylinder  26  and lubricant stick  6  and which is easily mounted in the bracket  20  being fixedly mounted on the trackbound vehicle. Hence safe function and quick changes are ensured. It is realized that it is also possible to, as alternative to changing said complete unit, at a change release the applicator cylinder  26 , take out the remaining stub of the lubricant stick  6 , and to push a new stick  6  into the applicator cylinder  26 , which is then again mounted in the bracket  20 . 
       FIG. 5  illustrates a lubricant holder  102  according to an alternative embodiment. The holder  102  has a bracket  120 , which is of the same type as the bracket  20  described with reference to  FIG. 2   a  and  FIG. 2   b  and is arranged to retain, in a similar manner, an applicator cylinder  126 , which preferably is cylindrical. 
     In its rear part  127  the applicator cylinder  126  has a gable  130  and a connection opening  132  for connecting a pipe  134  intended for supplying a pressurized fluid to the applicator cylinder  126 . 
     Contrary to the applicator cylinder  26  illustrated in  FIGS. 2   a  and  2   b  the applicator cylinder  126  illustrated in  FIG. 5  has a completely separate piston  136 . The separate piston  136  is provided with a sealing ring  145  which seals the piston  136  to the inner walls of the cylinder  126 . 
     When a pressurized fluid, such as pressurized air, is supplied to the applicator cylinder  126  this fluid will enter a cylinder space  137  which is formed between the piston  136 , the gable  130  and the walls of the cylinder  126 , and to press the piston  136  against a lubricant stick  106 , which is thereby pressed against the root  16  of the flange  14  and achieves the desired lubrication. 
     The applicator cylinder  126  is provided with a sealing ring  144  which seals against the stick  106 . In this embodiment the main task of the sealing ring  144  is to prevent dirt from entering the applicator cylinder  126 . The sealing ring  144  may also work as a stop which retains the piston  136 , and thereby the fluid in the space  137 , inside the cylinder  126  when the stick  106  has been completely worn out. 
     It will be appreciated that numerous variations of the embodiments described above are possible within the scope of the invention as defined by the appended claims.