Patent Publication Number: US-2018030966-A1

Title: Device of grease gun

Description:
FIELD 
     The disclosure relates to a device of a grease gun, more particularly to a device of a grease gun for delivering a viscous liquid to flow from a reservoir of the viscous liquid to a hose. 
     BACKGROUND 
     In a conventional grease gun, a reciprocating movement of a plunger is used for delivering lubricant from a reservoir to a hose, and is normally driven by a relatively complicated structure including multiple stages of planetary gears, a sliding member, etc. Therefore, the conventional grease gun is relatively bulky and heavy. In addition, because the conventional grease gun only has a single plunger, the lubricant does not flow out continuously. 
     For delivering lubricant continuously, Taiwanese patent no. I302973 discloses a conventional grease gun which includes a device  1  for delivering lubricant to flow from a reservoir  21  of the lubricant to a hose  24 , as shown in  FIG. 1 . The device  1  includes a head  10  (including a head body  11  and a head extension  111 ), two plungers  125 , a transmission unit  12 , and a drive unit  13 . 
     The head body  11  has two bores  110  and an outlet port  100 , and is mounted to the reservoir  21 . The head body  11  is configured to permit the lubricant to flow into the two bores  110  and then to the hose  24  through the outlet port  100 . The head extension  111  extends rearwardly from the head body  11 , and has a lower wall  112  and two sidewalls  113  which define thereamong a space  103 . The two plungers  125  are slidably disposed in the two bores  110 , respectively. Each of the two plungers  125  is displaceable between a rearward position and a forward position. When in the rearward position, the lubricant is free to flow into a corresponding one of the two bores  110 . When in the forward position, the lubricant in the corresponding one of the two bores  110  is pushed forward to flow out of the outlet port  111 . 
     The transmission unit  12  is disposed in the space  103  and includes a shaft  121 , a main gear  122 , two limiting members  123 , and two cam members  124  (only one is shown). The shaft  121  has two ends which are rotatably mounted to the sidewalls  113 , respectively. The main gear  122  is mounted for rotation on the shaft  121 . The two cam members  124  are mounted respectively on two opposite sides of the main gear  122  to rotate with the main gear  122 , and are disposed radially offset from the shaft  121 , respectively. In addition, the two cam members  124  are disposed opposite to each other relative to the shaft  121 . Each of the limiting members  123  has a stem segment  101  secured to a corresponding one of the two plungers  125 , and an annular segment  102  disposed to surround and engage a corresponding one of the two cam members  124 . When the main gear  122  is driven to rotate, a camming action between the annular segment  102  of a corresponding of the limiting members  123  and the corresponding one of the two cam members  124  causes a reciprocating motion of the corresponding one of the two plungers  125 . 
     The drive unit  13  has a motor  131  and a pinion gear  132  which is coupled to be driven by the motor  131  to rotate, and which is disposed to mesh with the main gear  122  so as to drive the main gear  122  to rotate. When the pinion gear  132  is driven to rotate, the main gear  122  is rotated such that the lubricant is alternately introduced into the two bores  110  and is alternately pushed by the two plungers  125  so as to permit the lubricant to continuously flow out of the outlet port  100 . 
     However, the conventional grease gun as shown in  FIG. 1  has the reservoir  21 , the head  10 , and the drive unit  12  extending in three different directions, and thus is not convenient for storage. 
     SUMMARY 
     Therefore, an object of the disclosure is to provide a novel device of a grease gun for delivering a viscous liquid to flow from a reservoir of the viscous liquid to a hose. With the novel device, the grease gun is light-weight and convenient for storage, and can be easily assembled. In addition, the viscous liquid can be delivered continuously by the grease gun. 
     According to the disclosure, a device for delivering a viscous liquid to flow from a reservoir of the viscous liquid to a hose is disclosed. The device includes a delivery head, two plungers, a cam member, and a drive source. The delivery head has an outlet port disposed for delivering the viscous liquid into the hose, two spaced apart bores, and an intake port. Each of the two bores is disposed to be in fluid communication with the outlet port. The intake port is disposed upstream of the two bores for receiving the viscous liquid from the reservoir. Each of the two plungers is slidably disposed in a corresponding one of the two bores to extend outwardly of the delivery head. The cam member has a cam path. The drive source is configured to drive the cam member to rotate about an axis. The axis extends in a longitudinal direction. Each of the two plungers is disposed to engage the cam path of the cam member such that rotation of the cam member is translated into linear reciprocating motions of the two plungers along the longitudinal direction to permit the viscous liquid to alternately flow into the two bores and then to flow out of the outlet port. 
     According to the disclosure, a device for delivering a viscous liquid to flow from a reservoir of the viscous liquid to a hose is disclosed. The device includes a delivery head, two check balls, a rear shell body, a drive source, two plungers, a cam member, and two biasing members. The delivery head extends in a longitudinal direction to terminate at a forward end and a rearward end. The delivery head has an intake port, two bores, two internal ports, an outlet port, and two valve seats. The intake port is disposed for receiving the viscous liquid from the reservoir. Each of the two bores extends in the longitudinal direction to terminate at a front valve hole and a rear through hole at the rearward end. Each of the two bores has a front zone adjacent to the front valve hole. Each of the two internal ports is disposed downstream of the intake port and upstream of the front zone of a corresponding one of the two bores. The outlet port is disposed downstream of the front valve holes of the two bores for delivering the viscous liquid into the hose. Each of the two valve seats defines the front valve hole of the corresponding one of the two bores. Each of the two check balls is disposed to couple with a corresponding one of the valve seats to permit a unidirectional flow of the viscous liquid from the front zone of the corresponding one of the two bores to the outlet port through the front valve hole of the corresponding one of the valve seats. The rear shell body is disposed rearwardly of the delivery head, and defines therein a chamber which extends forwardly to terminate at an open end in spatial communication with the rear through holes of the two bores. The drive source is disposed in the chamber, and has an output shaft configured to be driven to rotate about a shaft axis in the longitudinal direction. Each of the two plungers extends in the longitudinal direction to terminate at a plunger end segment and a follower end. The follower end is located in the chamber. The plunger end segment is slidably disposed in the corresponding one of the two bores, and is displaceable between a forward position, where a corresponding one of the two internal ports is prevented from fluid communication with the front zone of the corresponding one of the two bores, and a rearward position, where the corresponding one of the two internal ports is in fluid communication with the front zone of the corresponding one of the two bores to permit the viscous liquid to be introduced into the front zone of the corresponding one of the two bores through the corresponding one of the two internal ports. The cam member is disposed in the chamber, and is configured to be splinedly engaged with the output shaft so as to permit the cam member to rotate with the output shaft. The cam member has a front end which defines a cam path extending in a circumferential direction about the shaft axis. The cam path is configured to permit the follower ends of the two plungers to engage the cam path to provide a camming action such that when the cam member is driven by the output shaft to rotate, by virtue of the camming action, the plunger end segments of the two plungers are alternately displaced from the rearward position to the forward position so as to alternately force the introduced viscous liquid to flow through the front valve hole of the corresponding one of the valve seats to thereby establish a continuous flow of the viscous liquid out of the outlet port. Each of the two biasing members is disposed to bias the plunger end segments of a corresponding one of the two plungers toward the rearward position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the disclosure will become apparent in the following detailed description of the embodiment with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a conventional grease gun; 
         FIG. 2  is a perspective view of a grease gun according to an embodiment of the disclosure; 
         FIG. 3  is a perspective view of a portion of a delivering device mounted in the grease gun shown in  FIG. 2 ; 
         FIG. 4  is an exploded perspective view of the delivering device shown in  FIG. 3 ; 
         FIG. 5  is a cross-sectional view taken along line V-V of  FIG. 3 ; 
         FIG. 6  is a schematic view illustrating a cam path of a cam member in the delivering device; 
         FIG. 7  is a plot illustrating strokes of two plungers in the delivering device; 
         FIG. 8  is a cross-sectional view taken along line VIII-VIII of  FIG. 5 , illustrating one of two plungers is in a forward position; and 
         FIGS. 9 and 10  are similar to  FIG. 8  but illustrating the two plungers in different positions. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIG. 2 , a grease gun according to an embodiment of the disclosure includes a delivery device  2  for delivering a viscous liquid to flow from a reservoir  21  of the viscous liquid to a hose  24 . In this embodiment, the viscous liquid is lubricant. 
     As shown in  FIGS. 2 to 4 , the device  2  includes a delivery head  3 , two check valves  38 , a rear shell body  22 , a drive source  45 , two plungers  41 , a cam member  43 , and two biasing members  42 . 
     As shown in  FIGS. 5 and 8 , the delivery head  3  extends in a longitudinal direction (L) to terminate at a forward end  301  and a rearward end  302 . The delivery head  3  has an intake port  36 , two spaced apart bores  300 , two internal ports  330 , an outlet port  35 , and two valve seats  30 . 
     The intake port  36  is disposed for receiving the viscous liquid from the reservoir  21 . 
     Each of the two bores  300  extends in the longitudinal direction (L) to terminate at a front valve hole  333  and a rear through hole  306  at the rearward end  302 . Each of the two bores  300  has a front zone  331  which is disposed adjacent to the front valve hole  333  and in fluid communication with the outlet port  35 . 
     Each of the two internal ports  330  is disposed downstream of the intake port  36  and upstream of the front zone  331  of a corresponding one of the two bores  300 . 
     The outlet port  35  is disposed downstream of the front valve holes  333  of the two bores  300  for delivering the viscous liquid into the hose  24 . 
     Each of the two valve seats  30  defines the front valve hole  333  of the corresponding one of the two bores  300 . 
     In this embodiment, the delivery head  3  has a main wall  31  and a surrounding wall  32 . The main wall  31  includes a front segment  33  and a rear segment  34 , and has the two bores  300 , the two internal ports  330 , the outlet port  35 , and the two valve seats  30 . The front zone  331  of each of the two bores  300  is formed in the front segment  33 . The surrounding wall  32  extends downwardly from a periphery of the main wall  31  to define the intake port  36 , and is configured to be mounted to the reservoir  21 . 
     In this embodiment, as shown in  FIG. 2 , the reservoir  21  is of a cylindrical shape and has a replaceable cartridge with a spring-driven diaphragm (not shown) for urging the viscous liquid upward in the reservoir  21  toward the intake port  36  of the delivery head  3 . 
     Referring back to  FIG. 5 , it can be observed that each of the two bores  300  further has an accommodation zone  343 , a fitting zone  341 , and a neck zone  344 . The accommodation zone  343  has a first larger dimension, and is in radial alignment with a corresponding one of the two internal ports  330  to ease entry of the viscous liquid. The accommodation zone  343  is disposed to fluidly communicate the corresponding one of the two internal ports  330  with the front zone  331 . The fitting zone  341  has a second larger dimension, and is disposed adjacent to the rearward end  302  of the delivery head  3 . The neck zone  344  of a smaller dimension is disposed between the accommodation zone  343  and the fitting zone  341 , and defines, together with the fitting zone  341 , an abutment shoulder  345 . The fitting zone  341  and the neck zone  344  are formed in the rear segment  34 , and the accommodation zone  343  is formed between the front and rear segments  33 ,  34 . 
     As shown in  FIGS. 4, 5, and 8 , the delivery head  3  further has two front through holes  303  at the forward end  301 , and two valve ducts  332  each extending from a corresponding one of the front through holes  303  in the longitudinal direction (L) to be in spatial communication with the front valve hole  333  of a corresponding one of the valve seats  30 . As shown in  FIG. 5 , the valve ducts  332  are formed in the front segment  33 . 
     Each of the check valves  38  is disposed in a corresponding one of the two valve ducts  332 , and includes a check ball  381  disposed to couple with the corresponding one of the valve seats  30  to permit a unidirectional flow of the viscous liquid from the front zone  331  of the corresponding one of the two bores  300  to the outlet port  35  through the front valve hole  333  of the corresponding one of the valve seats  30 . 
     In this embodiment, each of the check valves  38  further includes an end cap  383  and a biasing spring  382 . The end cap  383  is disposed to be fitted into the corresponding one of the front through holes  301  and in liquid-tight engagement with the forward end  301 . The biasing spring  382  is disposed between the check ball  381  and the end cap  383  to bias the check ball  381  to couple with the corresponding one of the valve seats  30 . 
     Referring back to  FIG. 2 , it can be seen that the rear shell body  22  is disposed rearwardly of the delivery head  3  and defines therein a chamber  200 . The chamber  200  extends forwardly to terminate at an open end  201  in spatial communication with the rear through holes  306  of the two bores  300  (see  FIGS. 5 and 8 ). 
     As shown in  FIGS. 2, 4, 5, and 8 , the drive source  45  is disposed rearwardly of the delivery head  3  and in the chamber  200 , and has an output shaft  451  configured to be driven to rotate about a shaft axis (X) in the longitudinal direction (L). In this embodiment, the drive source  45  is configured to drive the cam member  43  to rotate about the shaft axis (X). 
     Each of the two plungers  41  extends in the longitudinal direction (L) to terminate at a plunger end segment  413  and a follower end  414 . The follower end  414  is located in the chamber  200 , and is disposed rearwardly of the delivery head  3 . The plunger end segment  413  is disposed in the corresponding one of the two bores  300 , and is displaceable between a forward position (see the upper one of the two plungers  41  in  FIG. 8 ) and a rearward position (see the upper one of the two plungers  41  in  FIG. 10 ). In the forward position, the corresponding one of the two internal ports  330  is prevented from fluid communication with the front zone  331  of the corresponding one of the two bores  300 . In the rearward position, the corresponding one of the two internal ports  330  is in fluid communication with the front zone  331  of the corresponding one of the two bores  300  to permit the viscous liquid to be introduced into the front zone  331  of the corresponding one of the two bores  300  through the corresponding one of the two internal ports  330 . 
     In this embodiment, as shown in  FIG. 8 , the two plungers  41  are substantially coplanar with the output shaft  451 . 
     The cam member  43  is disposed in the chamber  200 , and is configured to be splinedly engaged with the output shaft  451  so as to permit the cam member  43  to rotate with the output shaft  451 . As shown in  FIG. 4 , the cam member  43  has a front end  401  defining a cam path  430  which extends in a circumferential direction about the shaft axis (X), and which is configured to permit the follower ends  414  of the two plungers  41  to engage the cam path  430  to provide a camming action (see  FIGS. 5 and 8 ) such that when the cam member  43  is driven by the output shaft  451  to rotate, by virtue of the camming action, the plunger end segments  413  of the two plungers  41  are alternately displaced from the rearward position to the forward position so as to alternately force the introduced viscous liquid to flow through the front valve hole  333  of the corresponding one of the valve seats  30  to thereby establish a continuous flow of the viscous liquid out of the outlet port  35 . When the plunger end segment  413  of each of the two plungers  41  is displaced from the rearward position to the forward position, the check ball  381  of a corresponding one of the check valves  38  is forced by the viscous liquid to disengage from the corresponding one of the valve seats  30  so as to permit the viscous liquid to be pushed to the outlet port  35 . When the plunger end segment  413  of each of the two plungers  41  is displaced from the forward position to the rearward position, the check ball  381  of the corresponding one of the check valves  38  is urged by the biasing spring  382  to couple with the corresponding one of the valve seats  30 . In this embodiment, the cam member  43  is rotated in a clockwise direction as shown by an arrow (A) in  FIG. 6 . 
     As shown in  FIGS. 4 and 6 , the cam path  430  has a foremost area  433  and a rearmost area  434 . 
     The foremost area  433  is configured to permit the plunger end segment  413  of each of the two plungers  41  to reach the forward position (see the upper one of the two plungers  41  in  FIG. 8 ). 
     The rearmost area  434  is configured to permit the plunger end segment  413  of each of the two plungers  41  to reach the rearward position (see the upper one of the two plungers  41  in  FIG. 10 ). The foremost and rearmost areas  433 ,  434  are disposed opposite to each other relative to the shaft axis (X) so as to permit the plunger end segments  413  of the two plungers  41  to be alternately displaced from the rearward position to the forward position. 
     In this embodiment, the cam path  430  further has a front transition zone  435 , a rear transition zone  436 , a ramp-up zone  431 , and a ramp-down zone  432 . 
     The front transition zone  435  has the foremost area  433 . The rear transition zone  436  has the rearmost area  434 . The ramp-up zone  431  extends from the rear transition zone  436  in a counterclockwise direction to the front transition zone  435 . The ramp-down zone  432  extends from the front transition zone  435  in the counterclockwise direction to the rear transition zone  436 . 
     The ramp-up and ramp-down zones  431 ,  432  are configured such that when the cam member  43  is driven to rotate, one of the two plungers  41  (see the lower one of the two plungers  41  shown in  FIG. 9 ) engages the ramp-up zone  431  and is displaced toward the forward position to force the viscous liquid to flow out of the outlet port  35 , and the other one of the two plungers  41  (see the upper one of the two plungers  41  shown in  FIG. 9 ) engages the ramp-down zone  432  and is displaced toward the rearward position so as to permit the viscous liquid to flow into the front zone  331  of the corresponding one of the two bores  300 . 
       FIG. 7  illustrates a relation between a stroke of each plunger  41  and an angle position of each plunger  41 . The stroke of one of the two plungers  41  is shown by Line A, and the stroke of the other one of the two plungers  41  is shown by Line B. The longitudinal coordinate represents a distance of the follower end  414  of the corresponding one of the plungers  41  away from the rearmost area  434 . The transversal coordinate represents an angle position of the follower end  414  of the corresponding one of the plungers  41  relative to an initial position (0°), with respect to the shaft axis (X). Each of the follower ends  414  of the two plungers  41  goes through the cam path  430  for one circle (360°). The highest region of each of Lines A and B represents that the plunger end segment  413  of a corresponding one of the two plungers  41  reaches the foremost position. The lowest region of each of Lines A and B represents that the plunger end segment  413  of the corresponding one of the two plungers  41  reaches the rearmost position. It should be noted that a displacement time of one of the follower ends  414  of the two plungers  41  along the ramp-up zone  431  is substantially equivalent to a displacement time of the other one of the follower ends  414  of the two plungers  41  from the foremost area  433  along the ramp-down zone  432  to the rearmost area  434 . In this embodiment, the ramp-up zone  431  has a curvature configured to permit the viscous liquid to be supplied to the hose  24  at a constant flow rate. 
     As shown in  FIG. 5 , each of the biasing members  42  is disposed to bias the plunger end segment  413  of the corresponding one of the two plungers  41  toward the rearward position. 
     In this embodiment, the device  2  further includes two bushings  343  and two flange members  412 . 
     Each of the two bushings  343  has a front end  304  and a rear end  305 , and is fitted in the fitting zone  341  of the corresponding one of the two bores  300  such that the front end  304  abuts against the abutment shoulder  345  of the corresponding one of the two bores  300 . Because a liquid-tight seal is formed between each of the two bushings  343  and the corresponding one of the two plungers  41 , the viscous liquid can be prevented from leaking out of the delivery head  3  through the fitting zones  341  of the two bores  300 . 
     Each of the two flange members  412  is mounted on the corresponding one of the plungers  41  adjacent to the follower end  414 . Each of the two biasing members  42  is sleeved on the corresponding one of the two plungers  41  and is disposed between the rear end  305  of a corresponding one of the two bushings  342  and a corresponding one of the two flange members  412 . 
     In this embodiment, as shown in  FIG. 2 , the device  2  further includes two pressure relief valves  23  received respectively in two cavities  230  of the delivery head  3 . The two cavities  230  are in spatial communication with the two bores  300 , respectively. Each of the pressure relief valves  23  is configured to open when pressure of the viscous liquid in the corresponding one of the two bores  300  exceeds a predetermined level. 
     In this embodiment, as shown in  FIG. 5 , the device  2  further includes a shield member  44  disposed to connect the drive source  45  with the rearward end  302  of the delivery head  3 . The cam member  43  and the follower ends  414  of the two plungers  41  are disposed inside the shield member  44 . 
     In this embodiment, the grease gun further includes a power supply unit (not shown) which is disposed in the rear shell body  22  for supplying electricity to the drive source  45 . 
     In the description above, for the purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the embodiment. It will be apparent, however, to one skilled in the art, that one or more other embodiments may be practiced without some of these specific details. It should also be appreciated that reference throughout this specification to “one embodiment,” “an embodiment,” an embodiment with an indication of an ordinal number and so forth means that a particular feature, structure, or characteristic may be included in the practice of the disclosure. It should be further appreciated that in the description, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of various inventive aspects. 
     While the disclosure has been described in connection with what is considered the exemplary embodiment, it is understood that this disclosure is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.