Patent Publication Number: US-2015060496-A1

Title: Grease gun

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application derives priority from U.S. patent application Ser. No. 61/870,413, filed on Aug. 27, 2013, now pending, which is hereby incorporated in whole by reference. 
    
    
     FIELD 
     The present invention pertains to a grease gun and in particular to a battery operated grease gun with improved product life. 
     BACKGROUND 
     A conventional hand operated grease gun is basically comprised of a housing containing a pump mechanism comprised of a plunger that reciprocates in a tubular pump chamber, a check valve and discharge spout that communicate with the pump chamber, a grease reservoir that communicate with the pump chamber tube and is adapted to have a tubular body containing grease or a grease reservoir attached thereto, and a manually manipulated pump lever or handle that is pivotally connected to the housing and is connected to the pump plunger to reciprocate the plunger in the pump chamber on manual pivoting movement of the lever. In manually operated grease guns of this type, the rate at which the lever is manually pivoted determines the rate at which grease is dispensed through the discharge spout. In addition, the manual force exerted on the lever multiplied by the length of the lever used as leverage determines the force or pressure of the grease dispensed from the gun through the discharge spout. 
     Electric grease guns, such as those powered with batteries, eliminate the need to manually pivot the grease gun lever. One such grease gun is disclosed in U.S. Pat. No. 6,135,327, which is wholly incorporated herein by reference. Such grease gun has an electric motor that reciprocates the pump plunger to dispense grease under pressure from the grease gun. Many of the features of the manually operated grease gun are employed in the battery operated grease gun. Examples of battery operated grease guns and similar extruders are disclosed in the U.S. patents of Wegmann et al. U.S. Pat. No. 4,257,540, issued Mar. 24, 1981; Barry U.S. Pat. No. 5,404,967, issued Apr. 11, 1995; Shih et al. U.S. Pat. No. 5,609,274, issued Mar. 11, 1997; and Barry U.S. Pat. No. 5,685,462, issued Nov. 11, 1997, all of which are hereby incorporated by reference. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevation view, in section, of a battery operated grease gun of the present invention; 
         FIG. 2  is a partial front elevation view of the yoke and plunger of the grease gun taken along the line  2 - 2  of  FIG. 1 ; 
         FIG. 3  is a partial rear elevation view of the final driver taken along the line  3 - 3  of  FIG. 1 ; 
         FIG. 4  is a partial cross-sectional side view of another embodiment of the grease gun; and 
         FIG. 5  is a cross-sectional view along line V-V of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     The grease gun  10  of the present invention is shown in  FIG. 1 . The grease gun  10  basically comprises an electric motor  12  that drives a power transmission  14  that in turn drives a pump mechanism  16  that discharges grease under pressure through a discharge spout  18 . These component parts are preferably contained in or mounted on a housing  20 . 
     The housing  20  may be constructed of plastic as is typical in many prior art battery operated grease guns. The housing  20  is preferably constructed of several housing parts that are held together by fasteners (not shown), as also is conventional. The housing  20  may be constructed with a motor  12  and transmission compartment  22  on one side and a manual handle  24  on an opposite side. 
     The handle  24  is basically hollow and can be dimensioned to accommodate one or more batteries (not shown) in its interior. Alternatively, the bottom edge  26  of the handle can be designed for the attachment of a separate battery pack  25  represented by dashed lines in  FIG. 1 . A trigger  28  may be mounted on the handle  24  in a position where it can be easily manipulated by the index finger of a hand gripping the handle. The trigger  28  is preferably connected to an electric switch  29  that is selectively operated by manual manipulation of the trigger  28  to provide electric power from the battery pack  25  to the electric motor  12  to operate the motor  12 . The selective operation of the electric motor  12  in this manner is well known in the prior art. Persons skilled in the art shall recognize that the positioning of the handle  24 , the battery pack  25 , the electric motor  12  and power transmission  14  provides a distribution of the weight of the grease gun  10  that enables the grease gun  10  to be more easily manually manipulated while gripping the handle  24 . 
     The electric motor  12  is mounted in the motor and transmission compartment  22  of the housing  20  adjacent the power transmission  14  mounted in the compartment. The motor  12  preferably has an output shaft with a spur gear  30  mounted thereon. The output shaft and spur gear  30  may extend through an end wall  32  of a gear casing  34  of the power transmission  14 . The power transmission  14  may be contained in the gear casing  34  is a three stage planetary gearing reduction transmission. It is not necessary that the transmission have three stages of planetary gearing. Any number of planetary gear stages could be made to work depending upon the motor construction. 
     The output spur gear  30  of the electric motor  12  may also function as a sun gear of a first planetary gear set of the power transmission  14 . This spur gear  30  preferably drives three planet gears  36  (only one of which is seen in  FIG. 1 ) of a first carrier  38  of the first planetary gear set. The planet gears  36  preferably mesh with a first orbit gear  40  that is fixed to the gear casing  34  of the power transmission. Rotation of the output spur gear  30  of the electric motor may cause the first carrier  38  to rotate at a reduced speed while increasing the torque of the motor output. 
     A second sun gear  42  may be fixed to the first carrier  38 . This second sun gear  42  drives three planet gears (only one of which is shown in  FIG. 1 ) of a second planetary gear set of the power transmission  14 . The second series of planet gears  44  are mounted on a second carrier  46  and also mesh with the fixed orbit gear  40  of the first planetary gear set. This second planetary gear set further reduces the speed of rotation of the electric motor output and further increases its torque. 
     A third sun gear  48  is preferably fixed to the second planet gear carrier  46 . This third sun gear  48  may mesh with three planet gears  50  of a third planetary gear set of the power transmission  14 . The third set of planet gears  50  mesh with a second orbit gear  52  that is fixed to the gear casing  34  of the power transmission  14 . The third set of planet gears  50  are preferably mounted for rotation on a final driver  54 . This third planetary gearing arrangement further reduces the output speed of the electric motor  12  while increasing its torque. The planetary gearing arrangements of the power transmission  14  transform the output of the electric motor  12  reducing its speed while increasing its torque as it is transmitted to the final driver  54  causing rotation of the final driver. 
     A final driver  54  may have a circular drive surface  56  and a circular driven surface. The final driver has a cylindrical peripheral surface  60  that spaces the drive  56  and driven surfaces. A drive pin  68  with a cylindrical bushing  70  mounted for rotation thereon is preferably screw threaded into the drive surface  56 . 
     The gear casing  34  of the power transmission  14  has an annular collar  72  and the final driver  54  is mounted for rotation in the annular collar. As shown in  FIGS. 1 and 3 , the annular collar  72  has a cylindrical interior surface  76  that is radially spaced from the cylindrical peripheral surface  60  of the final driver  54 . Positioned between the cylindrical peripheral surface  60  of the final driver  54  and the cylindrical interior surface  76  of the annular collar is a roller bearing assembly  78  that mounts the final driver  54  for rotation in the annular collar  72 . On rotation of the output spur gear  30  of the electric motor  12 , the rotation is transmitted through the power transmission  14  to the final driver  54  and rotates the final driver in the annular collar  72  at a reduced speed of rotation from that of the motor output spur gear  30  and at an increased torque. The rotation of the final driver  54  is transmitted by the drive pin  68  and drive pin bushing  70  to a yoke  80  and plunger  82  of the pump mechanism  16 . 
     The yoke  80  has a generally square configuration with opposite pairs of side sliding surfaces  84 ,  86  spaced from each other by depressed surfaces  88 ,  90 , respectively, a bottom surface  92  and a top surface  94 . An oblong cam slot  100  passes through the yoke  80 . The cam slot  100  is dimensioned to receive the drive pin  68  and its bushing  70  therein allowing sufficient room to enable the drive pin  68  and bushing  70  to slide through the cam slot  100  freely from end to end. A transverse T-shaped slot  102  passes through the yoke bottom surface  92  and preferably receives the head  140 . 
     The plunger  82  preferably has a cylindrical shank that is sized to fit into the cylindrical pump chamber  124  so that the exterior surface of the shank engages in sliding engagement with the interior surface of the pump chamber  124 . The plunger has a bottom piston surface. Persons skilled in the art will recognize that, with such arrangement, when motor  12  rotates the output shaft, the final driver  54  will rotate as well, causing plunger  82  to reciprocate along its axis. 
     The pump mechanism  16  preferably includes a pump housing  122  that, in the embodiment shown in the drawings is an integral extension of the annular collar  72  of the gear casing  34 . The pump housing  122  preferably contains a cylindrical pump chamber  124  that is dimensioned to receive the plunger  82  in sliding engagement therein. As seen in  FIGS. 1 and 2 , the pump chamber  124  preferably aligns with the notch  120  in the slide box bottom wall  106 . This enables the plunger  82  positioned in the pump chamber  124  to extend upwardly through the notch  120  to its connection with the yoke  80  shown in  FIGS. 1 and 2 . 
     A resilient seal  126  is preferably positioned in an annular recess in the pump housing  122  and surrounds the plunger  82 . The seal  126  seals the pump chamber  124  from the slide box notch  120 . The pump chamber  124  also communicates with a lubricant supply passage  128 . The lubricant supply passage  128  communicates with the interior of a cylindrical skirt  130  of the pump housing  122 . The cylindrical skirt  130  has internal screw threading that is adapted to receive external screw threading on a cylindrical lubricant reservoir  131  of the type that is typically employed with grease guns. 
     The lubricant supply reservoir  131  contains either a supply of lubricant drawn therein or a cartridge of lubricant and has a spring biased plunger (not shown) that exerts a pressure on the lubricant contained in the reservoir. The pressure exerted by the plunger provides a continuous supply of lubricant to the supply passage  128 . The operation of the cylindrical lubricant reservoir is typical of prior art grease guns that are both manually and battery operated and therefore the reservoir is not shown in the drawing figures. 
     Preferably a filter  133  is disposed between lubricant supply reservoir  131  and plunger  82 . Filter  133  may be a mesh filter having holes between about 0.2 mm and about 1.0 mm. Preferably the holes in the filter  133  are about 0.54 mm. Filter  133  may be part of lubricant supply reservoir  131  or pump housing  122 . With such arrangement, 
     Page  7  debris particles can be trapped before entering pump chamber  124 , extending the life of grease gun  10 . 
     A ball check valve assembly  132  is preferably positioned in the bottom of the pump housing  122  communicating with the pump chamber  124  and is held in place by a screw threaded plug  134 . The chamber  124  also communicates with the discharge spout  18  of the grease gun  10 . The positioning of the ball check valve  132  and the discharge spout  18  shown in  FIG. 1  is common to many prior art grease guns. The reciprocation of the plunger  82  causes its bottom piston surface  138  to be retracted beyond the lubricant supply passage  124  enabling lubricant to enter into the pump chamber  124 . On the return stroke of the plunger  82 , the lubricant is pushed through the pump chamber  124  and is put under pressure. With increased pressure of the lubricant, the ball valve  132  unseats and enables the lubricant under pressure to pass through the ball valve chamber  132 C to the discharge spout  18 . This operation is typical in many prior art grease guns. 
     Preferably a rotational coupling (or rotary union)  18 R is provided between pump chamber  124  and discharge spout  18 . Such arrangement allows for the discharge spout  18  to be rotated towards a desired angle. Such arrangement also allows for more compact storage as discharge spout  18  can be rotated into a smaller envelope. 
       FIGS. 4-5  illustrate an alternate rotational coupling  18 R. In this embodiment, it would be desirable to make a portion of rotational coupling  18 R to be integral with pump housing  122 . Pump housing  122  may have a wall  122 W that creates a substantially cylindrical channel  122 C. 
     Rotational coupling  18 R may comprise a hose connector  18 RH for connecting to hose  18  and entering the channel  122 C at one end. Hose connector  18 RH may have a chamber  18 RHC extending therethough. In addition hose connector  18 RH may have a portion with a reduced diameter and/or holes  18 RHH extending from the chamber  18 RHC to the outer surface of hose connector  18 RH, so that the chambers  122 C and  18 RHC are connected. 
     At the other end of channel  122 C, a pressure relief valve  18 RV (and in particular valve coupling  18 RVC) may be threadingly engaged to hose connector  18 RH. Persons skilled in the art will recognize that the threaded engagement between hose connector  18 RH and valve coupling  18 RVC will preferably maintain rotational coupling  18 R within wall  122 W and chamber  122 C. 
     A plug  18 RVP may in turn be threadingly engaged to valve coupling  18 RVC. 
     Pressure relief valve  18 RV may include a valve  18 RVV, a spring  18 RVS valve  18 RVV biasing against valve coupling  18 RVC, and a ball plug  18 RVB sandwiched between valve  18 RVV and valve coupling  18 RVC. 
     With such arrangement, plunger  82  will pump grease into ball valve chamber  132 C. Such grease will move into chamber  122 C and enter chamber  18 RHC. The grease can then exit through hose  18  and/or pressure relief valve  18 RV. 
     Persons skilled in the art will recognize that rotational coupling  18 R preferably rotates about an axis that is substantially perpendicular to the axis of plunger  82  (and of pump chamber  124 ), and substantially coaxial with the axis of chamber  122 C. 
     While the present invention has been described by reference to a specific embodiment, it should be understood that modifications and variations of the invention may be constructed without departing from the scope of the invention defined in the following claims.