Patent Publication Number: US-2007119657-A1

Title: Lubricant supply device

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a lubricant supply device for supplying lubricant such as grease to an object of lubrication such as a part of various kinds of machines requiring lubrication.  
      2. Description of Related Art  
      In a lubricant supply device that supplies lubricant such as grease to an object of lubrication such as a part of a machine, in order to prevent air from getting into the supplied lubricant such as grease, air is removed from the lubricant and then the lubricant with air removed is supplied to the object of lubrication. If air is mixed into the grease or other such lubricant, because of the air present in the lubricant to be supplied, even if pressure is applied to the lubricant in order to continue to supply lubricant to the object of lubrication, the mixed-in air is compressed without the pressure being transmitted to the lubricant in front of it and the grease or other such lubricant does not reach every corner of the object of lubrications such as the lubricated parts of a variety of machines. For the above reason, air is removed from the grease or other such lubricant and the lubricant with air removed is supplied to the object of lubrication.  
      For example, in a method of greasing in which a cartridge filled with grease is loaded into a cartridge gun and supplied to an object of lubrication, providing an air bleed hole at the distal end of the grease filling area when filling an empty cartridge with grease so that, when a follow plate that is pushed back as the grease fills retreats to the rear of the bleed hole, any air that is mixed in with the grease is expelled together with any excess grease is known (JP 7-61484A).  
      In addition, a discharge device equipped with a supply tank that supplies grease to a discharge valve that discharges grease that is provided with an air bleed tap so that air bubbles do not get into the grease that is supplied from the supply tank is also known (JP 9-303683A).  
      The methods used conventionally for removing air from grease or other lubricants and supplying the lubricant to object of lubrications such as the lubricated parts of a machine are methods that remove air from inside a container that holds the lubricant (that is, a cartridge or a supply tank) like those described in JP 7-61484A and JP 9-303683A.  
      However, even providing the tank or other such receptacle that holds the lubricant with means for removing air and removing the air, there is a possibility that air mixed into the lubricant is not fully removed, and therefore there is no guarantee that air is not mixed into the lubricant that is actually supplied to the object of lubrication.  
     SUMMARY OF THE INVENTION  
      The present invention provides a lubricant supply device that reliably removes air from lubricant to be supplied to an object of lubrication and supplies the lubricant to the object of lubrication.  
      A lubricant supply device of the present invention supplies lubricant pressurized by a pump to an object of lubrication through a lubricant transporting path. The device comprises: a sensor for detecting air in the lubricant transporting path; air discharge means for discharging air from the lubricant transporting path; and a controller for controlling the air discharging means to discharge air from the lubricant transporting path in response to an air detection signal from the sensor.  
      The air discharge means may comprises switching means for selectively connecting the lubricant transporting path at a position downstream of the sensor to either a port for transporting lubricant or a port for discharging air; and actuating means for actuating the switching means, and the controller may control the actuating means to actuate the switching means so that the lubricant transporting path is connected to the port for discharging air when the air detection signal is issued from the sensor.  
      Air mixed in with the lubricant is detected and removed in the lubricant transporting path, and therefore the air is removed just before the grease is introduced into the object of lubrication, thus enabling lubricant in which no air is mixed into the lubricant to be more reliably supplied to the object of lubrication. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a diagram showing a schematic illustrative view of one embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION  
      A detailed description will now be given of a preferred embodiment of the present invention, with reference to the drawing.  
       FIG. 1  is a diagram showing a schematic illustrative view of one embodiment of the present invention. The present embodiment is comprised of a main unit  4  of a lubricant supply device, a controller  1  that controls the main unit  4 , a pump  2  that pressurizes and supplies grease (lubricant) to the main unit  4 , and a switching valve  3  that switches compressed air that drives a spool  5  that switches and connects a grease transporting path to either a grease discharge port or an air exhaust port.  
      The main unit  4  is comprised of a path switching member  9  in which is disposed a spool  5  that forms switching means for switching and connecting the lubricant transporting path to either a grease transporting port  14  or an air discharge port  15 , a sensor unit presser member  10 , and a return spring storage member  11 . A spool storage hole  12  that contains the spool  5  that forms the switching means, an introduction hole  13  for the compressed air that drives the spool  5 , a sensor container  17  that includes an hole section that forms a grease introduction hole  16 , the grease transporting port  14  and the air discharge port  15  are provided on the path switching member  9 . Moreover, a hole section that forms the grease introduction hole  16  is provided on the sensor unit presser member  10  so as to fix the sensor unit  6  contained in the sensor container  17  in place when the sensor unit presser member  10  is coupled to the path switching member  9 . A hole  18  that contains a return spring  8  is provided in the return spring storage member  11 .  
      The spool  5  forms a switching means that connects the grease introduction hole  6  with either the grease transporting port  14  or the air discharge port  15 . As is described later, when compressed air is not acting on the spool  5 , the action of the return spring  8  positions the spool  5  so that the grease introduction hole  16  and the grease transporting port  14  communicate with each other. In addition, the sensor unit  6  is equipped with an air detection sensor  7  consisting of a light sensor composed of a light-emitting element and a light-receiving element.  
      The spool  5  is inserted into the spool storage hole  12  of the path switching member  9 , the return spring  8  is inserted into the hole  18  of the return spring storage member  11 , the path switching member  9  and the return spring storage member  11  are connected by a bolt or the like, and the spool  5  is pushed by the force of the return spring toward one side of the spool storage hole  12  (to the left in  FIG. 1 ), connecting the grease introduction hole  16  and the grease transporting port  14 .  
      In addition, the sensor unit  6  is disposed within the sensor container  17  of the path switching member  9  and the sensor unit presser member  10  is tightly connected to the path switching member  9  by a bolt or the like, aligning the hole section of the grease introduction hole  16  in the path switching member  9  with the hole section of the grease introduction port  16  in the sensor unit presser member  10 .  
      Grease  19  is supplied to the grease introduction hole  16  through a grease supply path. In addition, a switching valve  3  that supplies compressed air  20  is connected to the compressed air introduction hole  13  as a driving means for driving the spool  5  of the switching means.  
      The controller  1  is connected to the air detection sensor  7 , the pump  2  and the switching valve  3 . The controller  1  turns the pump on and off, and controls the switching valve  3  based on signals from the air detection sensor.  
      When supplying the grease  19  to an object of lubrication such as the lubricated parts of a machine, the compressed air  20  is not introduced into the compressed air introduction hole  13  and the pressure of the return spring  8  causes the spool  5  to put the grease introduction hole  16  and the grease transporting port  14  into the state of communication shown in  FIG. 1 . When the pump  2  is operated, the grease  19  is discharged from the grease transporting port  14  via the grease introduction hole  16  and a chamber in the spool storage hole  12  that is divided by the spool  5 , and supplied to the object of lubrication such as the lubricated parts of the machine.  
      If during this supply of grease air that is mixed in with the grease passes that portion of the grease introduction hole  16  at which the sensor unit  6  is located, the air detection sensor detects the presence of this air and outputs an air detection signal to the controller  1 . The controller  1  receives the air detection signal, switches the switching valve  3 , introduces the compressed air  20  into the compressed air introduction hole  13 , and moves the spool to the right in  FIG. 1  against the force of the return spring  8 , connecting the grease introduction hole  16  with the air discharge port  15 . As a result, the air that is mixed in with the grease  19  is expelled from the air discharge port  15  and is not supplied to the object of lubrication such as the lubricated parts of the machine via the grease transporting port  14 .  
      When the air detection sensor  7  no longer detects air, the air detection signal turns off, causing the controller  1  to switch the switching valve and stopping the supply of compressed air to the compressed air introduction hole  13 . The spool  5  is then moved to the left in  FIG. 1  by the force of the return spring  8 , the grease introduction hole  16  and the grease transporting port  14  are aligned, and the grease  19  is supplied to the lubricated parts of the machine.  
      It should be noted that, in the embodiment described above, a light sensor is used as the air detection sensor. However, alternatively, it is possible to use another sensor that is capable of detecting air in the lubricant, such as a sensor that detects air using sound waves. In addition, although compressed air, a return spring and the like are used as means for driving the spool of the switching means that switches the lubricant transporting path, alternatively the spool may be driven using hydraulics.