Grease gun

Abstract

A grease gun is disclosed, comprising a body having first and second chambers, first and second pistons within the first and second chambers, primary and secondary grease passages, a grease outlet, and an actuator. Actuation of the actuator by a user causes the first and second pistons to move within the first and second chambers. The body may further include a pressure-sensitive valve core that allows the grease gun to move from high flow / low pressure operation to high pressure / low flow operation when a grease blockage is present, causing an increase in pressure within the body.

Description

Technical Field

[0001] The present invention relates to a lubricating grease gun, in particular to a manual lubricating grease gun. Background Art

[0002] Grease guns are used throughout industry to lubricate vehicles and other machinery. These grease guns typically consist of a grease supply (from an attached cartridge or external source) and a piston that forces the grease out of an outlet under pressure so that it can be applied to the associated machinery for lubrication. Grease guns can be categorized into two main types: manual grease guns and power-assisted grease guns (the latter include battery-operated, pneumatic, and electric grease guns).

[0003] When greasing vehicles or machinery, clogged grease points often result in high grease pressures. Common causes of high grease pressures include clogged Zerc devices, long, winding, and / or tight grease channels, and thick, difficult-to-flow grease. Previous systems have been developed to provide additional pressure to the grease to clear the blockage. Some systems use external power sources to provide this additional pressure. However, this can be expensive and impractical.

[0004] Manual grease guns have been developed that can move between a high volume / low pressure mode, where the high pressure provided in the low volume / high pressure mode can clear a clog, and a low volume / high pressure mode. These systems typically require the user to manually switch between the two modes.

[0005] In recent years, a small number of systems have been developed that can switch a grease gun to low-volume / high-pressure mode when pressure increases due to a blockage. However, these systems still have limitations. For example, while these systems can provide a way to switch the grease gun to low-volume / high-pressure mode, they can be difficult to use and require a significant amount of pressure from the user to operate in this mode.

[0006] Where in this specification a document, act or item of knowledge is referenced or discussed, such reference or discussion is not an admission that the document, act or item of knowledge, or any combination thereof, was publicly available, known to the public, part of the common general knowledge at the priority date; or was known to be relevant to an attempt to solve any problem with which this specification is concerned. Summary of the Invention

[0007] The present invention discloses a grease gun, comprising: a main body, which is connectable to a container configured to store grease, wherein a first elongated chamber and a second elongated chamber are defined in the main body, wherein the first chamber extends along a first axis, and the second chamber extends along a second axis, the first axis is spaced apart from the second axis, and the second chamber has a smaller cross-sectional area than the first chamber; a first piston and a second piston, wherein the first piston is configured to reciprocate along the first axis in the first chamber, and the second piston is configured to reciprocate along the second axis in the second chamber, and the second piston has a smaller cross-sectional area than the first piston; a primary grease channel and a secondary grease channel, wherein the primary grease channel is provided between the container and the first chamber so that The grease gun includes a container fluidically connectable to the first chamber, a secondary grease passage disposed between the first and second chambers to allow grease to flow from the first chamber into the second chamber, an actuator connected to the body and movable between a retracted position in which grease can flow through the primary grease passage and an engaged position in which grease is restricted from flowing through the primary grease passage, the actuator being configured to reciprocate the first and second pistons when moved between the engaged and retracted positions, and a grease outlet fluidically connected to the second chamber to allow grease to be discharged from the grease gun. The grease gun disclosed herein may provide advantages over prior art grease guns, particularly prior art manual grease guns, or at least provide a useful alternative to prior art grease guns.

[0008] In some forms, the secondary grease passage is disposed midway along the length of the first and second chambers.

[0009] In some forms, the secondary grease passage extends along a secondary grease axis that extends substantially perpendicular to the first and second axes. Preferably, the first axis is parallel to the second axis.

[0010] In some embodiments, the grease gun further includes a first check valve disposed in the second passageway. The first check valve allows grease to flow from the first chamber into the second chamber. Preferably, the first check valve restricts grease from flowing from the second chamber into the first chamber. More preferably, the first check valve prevents grease from flowing from the second chamber into the first chamber.

[0011] In some embodiments, the grease gun further includes an outlet cavity between the second chamber and the grease outlet, the outlet cavity including a second check valve that allows grease to flow from the second chamber into the grease outlet. Preferably, the second check valve restricts grease from flowing from the outlet cavity into the second chamber. More preferably, the second check valve prevents grease from flowing from the outlet cavity into the second chamber.

[0012] In some embodiments, the first chamber further comprises a tertiary grease passage. Preferably, a third check valve is provided within the tertiary grease passage, allowing grease to flow into the first chamber. More preferably, the third check valve restricts grease from flowing from the first chamber into the container. Most preferably, the third check valve prevents grease from flowing from the first chamber into the container.

[0013] In some forms, the actuator has an intermediate position between the retracted position and the engaged position, wherein when the actuator is in the intermediate position, grease is restricted from flowing through the primary grease passage into the first chamber, but is not restricted from flowing through the tertiary grease passage into the first chamber. Preferably, the actuator is configured to reciprocate the first piston and the second piston in phase when moving between the engaged position, the intermediate position, and the retracted position.

[0014] In some forms, the grease gun further includes a container connected to the body.

[0015] In some forms, the grease gun further comprises a mount configured to pivotally connect the actuator to the body; and first and second biasing devices disposed about the first and second pistons, respectively, and each configured to bias the actuator toward the retracted position. Preferably, the actuator comprises first and second lugs configured to engage the first and second pistons, respectively, wherein movement of the actuator from the retracted position toward the engaged position causes the first and second lugs to engage the first and second pistons, respectively, to move the first and second pistons along the first and second axes, respectively.

[0016] A grease gun is also disclosed herein, which further includes: a first valve core channel, which extends along a third axis; a valve core, which can move between an open position and a closed position in the first valve core channel; and a bypass channel, which is fluidically connected to the first chamber and the container through the first valve core channel; wherein, when the valve core is in the open position, the valve core allows grease to flow out of the first chamber to the grease barrel, and when the valve core is in the closed position, the valve core restricts the grease from flowing out of the first chamber to the grease barrel.

[0017] In some forms, in use, when the valve core is in the open position, the valve core allows grease to flow out of the first chamber into the container, and when the valve core is in the closed position, the valve core restricts the flow of grease out of the first chamber into the container. Preferably, when the valve core is in the closed position, the valve core prevents the grease from flowing out of the first chamber into the container.

[0018] Also disclosed herein is a grease gun, comprising a pressure channel disposed at a first end of a valve core passage, the pressure channel being in fluid communication with an outlet chamber; and a third biasing device disposed at a second end of the valve core passage, the third biasing device being configured to bias the valve core toward a closed position, wherein an increase in pressure in the outlet chamber causes an increase in pressure in the pressure channel and an increase in pressure at the first end of the first passage, thereby forcing the valve core against the third biasing device. Preferably, the valve core is configured to move toward the open position at a predetermined pressure level at the first end of the first passage.

[0019] In some forms, the bypass channel includes a primary bypass channel disposed between the first chamber and the spool channel, and a secondary bypass channel disposed between the spool channel and the reservoir. Preferably, the primary bypass channel extends along a primary bypass channel axis, while the secondary bypass channel extends along a secondary bypass channel axis, with the primary bypass channel axis being offset relative to the spool channel and secondary bypass channel axes. More preferably, the primary bypass channel axis is substantially perpendicular to and spaced apart from the secondary bypass channel axis.

[0020] In some forms, the spool passage is connected to the primary bypass passage and the secondary bypass passage and is disposed between the primary bypass passage and the secondary bypass passage so that grease can flow from the primary bypass passage through the spool passage into the secondary bypass passage when the spool is in the open position.

[0021] In some forms, the valve core includes: a first annular ring and a second annular ring, the second annular ring being spaced apart from the first annular ring; and an intermediate section, the intermediate section being disposed between the first annular ring and the second annular ring and being bounded by the first annular ring and the second annular ring; the intermediate section of the valve core has a diameter that is smaller than the diameter of the valve core channel and the diameters of the first annular ring and the second annular ring; wherein an area disposed between the intermediate section of the valve core and a wall of the valve core channel forms a communicating channel, and the communicating channel is fluidically connected to the primary bypass channel regardless of whether the valve core is in an open position or a closed position.

[0022] In some forms, the valve core includes a cavity extending through the valve core, the cavity being disposed in a middle section of the valve core to allow grease to flow through the middle section of the valve core and fill the communication passage.

[0023] In some forms, when the spool is in the closed position, the communication passage is positioned not adjacent to the secondary bypass passage, thereby restricting grease from flowing from the spool passage into the secondary bypass passage, and when the spool is in the open position, the communication passage is positioned adjacent to the secondary bypass passage, thereby allowing grease to flow into the secondary bypass passage. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Various embodiments / aspects of the present disclosure will be described below with reference to the following drawings, in which:

[0025] Figure 1 is a cross-sectional view of a grease gun according to a first embodiment of the present invention.

[0026] Figure 2 yes Figure 1 Cross-sectional view of a grease gun showing the positions of the first piston and the second piston when the actuator is in the retracted position.

[0027] Figure 3 yes Figure 1 Cross-sectional view of a grease gun showing the positions of the first piston and the second piston when the actuator is in the engaged position.

[0028] Figure 4 yes Figure 1 Cross-section of a grease gun with the valve core in the closed position.

[0029] Figure 5 yes Figure 1 Cross-section of a grease gun with the valve core in the open position.

[0030] Figure 6 yes Figure 1 Cross-section of a grease gun with the pressure-sensitive valve core in the closed position.

[0031] Figure 7 yes Figure 1 Cross-section of a grease gun with the pressure-sensitive valve core in the open position.

[0032] Figure 8 yes Figure 1 A perspective view of the body of a grease gun, showing the filler / bleeder.

[0033] Figure 9 It passes through Figure 1 Cross-sectional view of the body of a grease gun.

[0034] Figure 10 It passes through Figure 1 Another cross-sectional view of the body of the grease gun with the third bias spring in a high preload state.

[0035] Figure 11 It passes through Figure 1 Another cross-sectional view of the grease gun body with the adjusting screw in a low preload state.

[0036] Figure 12 A cross-sectional view through a second embodiment of a grease gun is provided.

[0037] Figure 13 Provides a pass through Figure 12 Another cross-sectional view of the grease gun shown.

[0038] Figure 14 A cross-sectional view through a third embodiment of a grease gun is provided.

[0039] Figure 15 Provides a pass through Figure 14 Another cross-sectional view of the pressure relief valve in the grease gun shown.

[0040] Figure 16 Provides a pass through Figure 14 Another cross-sectional view of the grease gun is shown.

[0041] Figure 17 Provides a pass through Figure 14 Another cross-sectional view of the pressure relief valve in the grease gun shown. DETAILED DESCRIPTION

[0042] The following will refer to Figures 1 to 11 The present disclosure is described with reference to a first embodiment of a grease gun as shown.

[0043] The present disclosure relates to a grease gun 1. Figure 1 As shown, the grease gun 1 includes an actuator in the form of a handle 2 and a body 3. In use, the body 3 is connected to a container in the form of a grease barrel 4. In a detailed embodiment, the body 3 is connected to the grease barrel 4. The grease barrel 4 is designed to be filled with a standard grease cartridge or with bulk grease from a grease source. When the grease barrel 4 is empty, if a grease cartridge is used, the grease barrel 4 will be disconnected from the body 3 to access and replace the grease cartridge; if bulk filling is used, when the grease barrel 4 is empty, the grease barrel 4 can be connected to a grease source for refilling via a filler / drainer 34 (see Figure 8 and Figure 9 ).

[0044] The following will refer to Figure 2 and Figure 3 A grease gun is described in more detail, wherein Figure 2 and Figure 3 A cross-sectional view through a body 3 of a grease gun 1 is provided. The body 3 includes an elongated first chamber 5 and an elongated second chamber 6. The second chamber 6 has a smaller cross-sectional area relative to the first chamber 5, and the second chamber 6 is configured to hold a smaller volume of grease than the first chamber 5. In a detailed embodiment, the first chamber 5 and the second chamber 6 are circular in cross-section, and the second chamber 6 has a smaller diameter relative to the first chamber 5, with the first chamber 5 extending along a first axis A and the second chamber 6 extending along a second axis B, with the axes spaced apart. Figure 2 and Figure 3 In the detailed embodiment shown, the first axis A and the second axis B are substantially parallel to each other. The first piston 7 is movable within the first chamber 5 so that the first piston 7 moves along the first axis A (horizontally translates); the second piston 8 is movable within the second chamber 6 so that the second piston 8 moves along the second axis B (horizontally translates). If the pistons can still be actuated with the same phase by the handle 2, the axes may not be parallel to each other. The first piston 7 is equipped with an active seal 7A to form a liquid-tight joint with the first chamber 5. The second piston 8 is equipped with an active seal 8A to form a liquid-tight joint with the second chamber 6. In the detailed embodiment, the active seal is in the form of an O-ring, but the active seal may also take other forms, for example, an O-ring with a retaining ring, a rod seal, or a lip seal.

[0045] The first piston 7 and the second piston 8 are reciprocated along the first axis A and the second axis B, respectively, by the user moving the handle 2 between the retracted position and the engaged position through an intermediate position (not shown) therebetween. When the handle 2 is in the retracted position, the first piston 7 is located in a position within the first chamber 5 where it does not block the flow of grease from the grease barrel 4 into the first chamber 5 via the primary grease passage 9. In other words, the first piston 7 is disposed in a retracted position within the first chamber 5. When the handle 2 is moved from its retracted position to its intermediate position (i.e., toward the engaged position of the actuator, which corresponds to the extended position of the first piston 7), the first piston 7 advances within the first chamber 5 (e.g., translates horizontally along the axis A) and gradually blocks and ultimately closes (e.g., blocks) the primary grease passage 9.

[0046] The handle 2 is pivotally connected to the body 3 via a pin 10. This allows the handle 2 to pivot relative to the body 3 between a retracted position and an engaged position. The first and second pistons 7, 8 are also connected to the handle 2 via lugs 11 located on the handle 2. In a detailed embodiment, the lugs 11 are in the form of metal rollers on a rod extending through the handle 2. Between the handle 2 and the body 3, first and second biasing devices are located in portions of the first and second pistons 7, 8, respectively. The first and second biasing devices are disposed around the first and second pistons 7, 8. In a detailed embodiment, the first and second biasing devices are in the form of first and second biasing springs 12, 13, although other biasing devices are also contemplated within the present disclosure. The first and second biasing springs 12, 13 are compression springs configured to bias the handle 12 toward the retracted position. Therefore, when the user removes pressure on the handle 2, the handle 2 pivots toward the retracted position, where it remains until further pressure is applied.

[0047] When the handle is in the retracted and intermediate positions, the tertiary grease passage 14 is open and allows grease to flow from the grease barrel 4 into the first chamber 5. As the handle 2 moves from the intermediate position to the engaged position, the first piston 7 advances within the first chamber 5, gradually blocking and ultimately closing the tertiary grease passage 14. The tertiary grease passage 14 contains a check valve, shown in the form of a spring-loaded check valve 15. When open, the check valve allows grease to flow from the grease barrel 4 through the tertiary grease passage 14 into the first chamber 5, but restricts grease from flowing back into the grease barrel 4 through the tertiary grease passage 14. By default, the check valve 15 is closed and opens only when the grease in the grease barrel 4 exerts sufficient pressure on the check valve 15 to overcome the biasing force of the spring. In the illustrated embodiment, the check valve 15 prevents grease from flowing back into the grease barrel 4 from the first chamber 5. The first chamber 5 and the second chamber 6 are in fluid communication with each other via the secondary grease passage 16. Once the first piston 7 closes the primary grease passage 9, back pressure on the grease in the first chamber 5 increases because the grease in the first chamber 5 is confined to a volume that decreases in size as the first piston 7 advances within the first chamber 5 along the first axis A. Due to the closure of the primary grease passage 9 and due to the check valve 15, the grease cannot travel back into the grease gun barrel 4.

[0048] The secondary grease passage 16 contains a check valve, shown in the form of a spring-loaded check valve 17. By default, the check valve 17 is closed and opens only when the grease in the first chamber 5 exerts sufficient pressure on the check valve 17 to overcome the biasing force from the spring. As the first piston 7 moves further along the first axis A within the first chamber 5 and the pressure on the grease within the first chamber 5 increases due to the volume reduction, the check valve 17 opens, and grease is able to pass from the first chamber 5 into the second chamber 6. The check valve 17 allows grease to flow from the first chamber 5 through the secondary grease passage 16 into the second chamber 6, but restricts grease from flowing back from the second chamber 6 into the first chamber 5. In the illustrated embodiment, the check valve 17 prevents grease from flowing back from the second chamber 6 into the first chamber 5.

[0049] Movement of the handle 2 causes the first piston 7 and the second piston 8 to reciprocate in phase. Therefore, as the first piston 7 advances along the first axis A within the first chamber 5, the second piston 8 also advances along the second axis B within the second chamber 6. As grease flows from the first chamber 5 through the secondary grease passage 16 into the second chamber 6, it is pushed into the outlet chamber 18 by the second piston 8. This forces the combined volume of grease displaced by the first and second pistons 7 and 8 through the outlet chamber 18. The outlet chamber 18 contains a check valve, shown as a spring-loaded check valve 19. By default, the check valve 19 is closed and opens only when the grease in the second chamber 6 exerts sufficient pressure on the check valve 19 to overcome the biasing force of the spring. When open, the check valve 19 allows grease to flow from the second chamber 6 into the outlet chamber 18, but restricts grease from flowing back from the outlet chamber 18 into the second chamber 6. In the embodiment shown, the non-return valve 19 prevents the grease from flowing back from the outlet chamber 18 into the second chamber 6 .

[0050] The outlet chamber 18 also includes a grease outlet 20. In use, when the handle 2 is moved from the retracted position to the engaged position (e.g., when the pistons are moved toward their respective extended positions), grease from the outlet chamber 18 will flow out of the grease gun 1 through the grease outlet 20. In this way, grease can be applied to an area of ​​interest on a vehicle, machine, or other equipment that requires lubrication at a specific location.

[0051] like Figure 2 and Figure 3 As shown, in order for grease to flow through the primary grease passage 9, the handle 2 must be in or near (e.g., positioned toward) the retracted position. By allowing grease to flow into the first chamber 5 via the primary grease passage 9 and the tertiary grease passage 14, the amount of grease collected during each stroke is maximized, thereby maximizing the amount of grease that can flow from the grease outlet 20. However, the user may only require a small volume of grease output (typically when grease filling against high back pressure). Thus, the handle 2 can be operated in short partial strokes, moving only between the intermediate and retracted positions, with the primary grease passage 9 remaining closed. In this operation, grease only flows from the tertiary grease passage 14 into the first chamber 5 during a particular stroke of the handle 2. These shorter strokes, compared to the force required to move the handle through a full stroke from the retracted to the engaged position, limit the amount of grease that can be applied to the handle when only a small volume of grease output is required.

[0052] Now refer to Figure 4-7 Describe the grease gun in more detail. Figure 4 and 5As shown, in a detailed embodiment, the main body 3 of the grease gun 1 further includes a valve core channel 21 extending along the third axis C. Figure 6 and Figure 7 As shown, the spool passage 21 is bounded (e.g., defined) by a wall 22 (e.g., the passage 21 is formed within the body 3 of the grease gun 1). The third axis C is parallel to the first axis A and the second axis B, although this is not required. The third axis C can be at any angle between parallel and perpendicular to the first axis A and the second axis B. The spool 23 is movable within the spool passage 21. In a detailed embodiment, the spool 23 translates between an open position and a closed position.

[0053] A pressure passage 24 is provided at the first end 21A of the spool passage 21 and is in fluid communication with the outlet chamber 18. When grease is present in the outlet chamber 18, a portion of the grease will pass through the pressure passage 24. In a detailed embodiment, the pressure passage 24 is provided perpendicular to the spool passage 21.

[0054] The spool 23 has a central section 25. The central section 25 of the spool 23 is disposed between a first annular ring 26 and a second annular ring 27 of the spool 23. In a detailed embodiment, the central section 25, the first annular ring 26, and the second annular ring 27 of the spool 23 are integrally formed components. The diameter of the central section 25 is smaller than the diameter of the spool passage 21 and the diameters of the first annular ring 26 and the second annular ring 27. This arrangement forms a gap, in the form of a communication passage 28, between the central section 25 of the spool passage 21 and the surrounding wall 22. The first annular ring 26 and the second annular ring 27 are equipped with high-pressure seals and form a fluid-tight engagement with the wall 22 of the spool passage 21, thereby preventing grease from entering the passage 28 from the pressure passage 24 around the central section 25 through the first annular ring 26, and preventing grease from exiting the passage 28 around the central section 25 through the first annular ring 26 and the second annular ring 27. In other words, the intermediate section 25 , the first annular ring 26 , the second annular ring 27 , and the area (eg, the gap) between the wall 22 form the communication channel 28 .

[0055] Regardless of whether the valve core 23 is in the open position or the closed position, the first end 23A of the valve core 23 deviates from the first end 21A of the valve core channel 21, so that grease from the pressure channel 24 can flow into the portion of the valve core channel 21 adjacent to the first end 23A of the valve core 23.

[0056] A third biasing means is located at the second end 21B of the spool passage 21 and is shown in the form of a third biasing spring 29, although other biasing means are also contemplated within the present disclosure. The third biasing spring 29 is adjacent the second end 23B of the spool 23 and biases the spool 23 to the closed position.

[0057] A bypass channel is located between the first chamber 5 and the grease gun barrel 4 and includes a primary bypass channel 30A and a secondary bypass channel 30B. The primary bypass channel 30A is positioned between the first chamber 5 and the spool passage 21 such that, when grease is present in the first chamber 5, the grease flows through the primary bypass channel 30A and into the communication channel 28. The secondary bypass channel 30B is positioned between the spool passage 21 and the grease gun barrel 4. In the illustrated embodiment, the primary bypass channel axis (extending along its longitudinal axis) and the secondary bypass channel axis (extending along its longitudinal axis) are substantially perpendicular to each other and offset relative to the spool passage 21. In a detailed embodiment, when the grease gun 1 is in an upright position, the primary bypass channel axis D forms a horizontal axis, while the secondary bypass channel axis E forms a vertical axis. Thus, the section of the spool passage 21 connected to the primary bypass channel 30A is spaced apart from the section of the spool passage 21 connected to the secondary bypass channel 30B. Therefore, any grease that enters the spool passage 21 from the primary bypass passage 30A must flow along at least a portion of the length of the spool passage 21 before entering the secondary bypass passage 30B.

[0058] like Figure 6 As shown, when the spool 23 is in the closed position, the communication passage 28 is positioned not adjacent to the secondary bypass passage 30B. This means that the communication passage 28 is spaced apart from the secondary bypass passage 30B and is therefore not in fluid communication with the secondary bypass passage 30B. Therefore, in the closed position, any grease in the communication passage 28 does not enter the secondary bypass passage 30B.

[0059] like Figure 7 As shown, when the valve core 23 is in the open position, the communication channel 28 is positioned adjacent to the secondary bypass channel 30B. This means that the communication channel 28 is in fluid communication with the secondary bypass channel 30B, and any grease in the communication channel 28 will enter the secondary bypass channel 30B and then enter the grease gun barrel 4.

[0060] The middle section 25 may also contain a cavity 31. Figure 6 As shown, grease will flow from the primary bypass passage 30A through the cavity 31 into the communication passage 28. In a detailed embodiment, the cavity 31 extends through the intermediate section 25 in the same orientation as the primary bypass passage 30A and generally perpendicular to the orientation of the secondary bypass passage 30B. Figure 6 As shown, when the valve core 23 is in the closed position, although the grease can flow along the primary bypass channel 30A through the cavity 31 into the communication channel 28, the grease will be prevented from entering the secondary bypass channel 30B by the second annular ring 27.

[0061] As described above, the third biasing spring 29 biases the valve spool 23 to the closed position. If a clogged grease filling point exists, the grease pressure in the outlet chamber 18 will increase with each stroke of the handle 2. Due to the check valve 19, grease from the outlet chamber 18 is restricted from returning to the second chamber 6. However, grease from the outlet chamber 18 is not restricted from entering the valve spool passage 21 along the pressure passage 24. As a result, the grease between the first end 21A of the valve spool passage 21 and the first end 23A of the valve spool 23 is under increasing pressure. At an adjustable predetermined pressure level (e.g., set to a level between 1000 psi and 3000 psi, preferably between 1500 psi and 2500 psi, and most preferably 2000 psi), the force from this pressure will be greater than the force applied by the third biasing spring 29, causing the valve spool 23 to move from the closed position to the open position against the third biasing spring 29. The pressure from the grease in the outlet chamber 18 will maintain the valve plug 23 in the open position while the grease outlet 20 remains blocked.

[0062] In a detailed embodiment, the predetermined pressure level of the third biasing spring 29 is set by an adjustment screw 35. Figure 10 and Figure 11 As shown, the adjustment screw 35 is located at the end of the third bias spring 29 opposite the end that engages the valve core 23. The adjustment screw 35 has a tool engagement portion 36 located on the exterior of the body. The tool engagement portion 36 can be any suitable shape. For example, the tool engagement portion 36 can be hexagonal, such as Figure 10 and Figure 11 Tightening and loosening the adjusting screw 35 by rotating it through the tool engaging portion 36 allows the user to change the preload of the third biasing spring 29, such that tightening the adjusting screw 35 will increase the preload on the third biasing spring 29 and increase the predetermined pressure level required to overcome the force applied by the third biasing spring 29 (e.g., Figure 10 As shown), loosening the adjustment screw 35 will reduce the preload on the third biasing spring 29 and reduce the predetermined pressure level required to overcome the force applied by the third biasing spring 29 (as shown). Figure 11 shown).

[0063] Figure 12 and Figure 13 An alternative embodiment of a device configured to enable the third biasing spring 29 to have a predetermined pressure level is shown. Figure 10 and Figure 11In contrast to the embodiment shown in which the orifice through which the adjustment screw 35 extends has a uniform diameter, the orifice is stepped (e.g., varies in diameter). The orifice includes a first portion 37a and a second portion 37b. The first portion 37a of the orifice has a larger diameter than the second portion 37b of the orifice. An annular wall 38 is formed around the barrel 39 at the junction between the first portion 37a and the second portion 37b (e.g., where the diameter of the orifice expands in diameter). Figure 10 and 11 In contrast to the embodiment described in , in which the adjusting screws have a substantially uniform diameter, Figure 12 and 13 The adjusting screw shown in FIG. 1 has an elongated narrow portion 40a and a head 40b. The head 40b of the adjusting screw is configured to threadably engage the first portion 37a of the aperture. The elongated narrow portion 40a is configured to extend through the second portion 37b of the aperture to engage the spring 29 (or, as shown in the detailed embodiment, the engagement mechanism 29a that cooperates with the spring 29). The adjustment mechanism can be configured in the same manner as described above with respect to Figure 10 and 11 The method is controlled in a similar manner as described above.

[0064] The lengths of the head 40b and the elongated portion 40a of the adjusting screw, and the lengths of the first and second portions 37a and 37b of the aperture are configured to limit the distance the adjusting screw can be inserted into the aperture. Figure 10 and Figure 11 Tightening and loosening the adjusting screw by rotating the adjusting screw (as described above) allows the user to change the preload of the third bias spring 29, such that tightening the adjusting screw will increase the preload on the third bias spring 29 and increase the predetermined pressure level (e.g., the pressure applied by the third bias spring 29) required to overcome the force applied by the third bias spring 29. Figure 12 Loosening the adjustment screw will reduce the preload on the third biasing spring 29 and thereby reduce the predetermined pressure level required to overcome the force applied by the third biasing spring 29 (as shown). Figure 13 relative to Figure 10 and Figure 11 In the embodiment described in

[0045] , this design can reduce or completely avoid over-compression of the spring. The adjusting screw abuts against the annular wall 38 of the barrel 39, and after the adjusting screw is rotated a predetermined number of times (e.g., 3 turns), the adjusting screw seats on the annular wall, thereby providing a mechanical stop to protect the spring from over-compression.

[0065] When the valve core 23 is in the closed position, the grease gun is considered to be operating in "high flow mode." In high flow mode, all grease contained in the first chamber 5 is directed to the second chamber 6 to enter the outlet chamber 18 and then to the grease outlet 20. In this mode, the first piston 7 and the second piston 8 are subject to the same back pressure, and actuation of the handle 2 requires sufficient force to advance both pistons against the back pressure.

[0066] When the valve spool 23 is in the open position, the grease gun is considered to be operating in "high-pressure mode." In high-pressure mode, the primary bypass passage 30A and the secondary bypass passage 30B are connected via the communication passage 28, and a large amount of grease that enters the first chamber 5 via the primary grease passage 9 and the tertiary grease passage 14 will flow back from the first chamber 5 into the grease gun barrel 4 via the bypass passage 30. This amount of grease varies depending on a number of parameters, including the back pressure level within the chambers, the speed at which the trigger is actuated, the grease viscosity, temperature, and the like.

[0067] When the bypass channel 30 is in the open position, the grease in the first chamber 5 will return to the grease gun barrel 4 through the bypass channel 30 along the path of least resistance. However, when the first piston 7 advances, the size of the outlet channel (bypass channel 30) from the first chamber 5 is smaller than the inlet channel (tertiary grease channel 14 and / or primary grease channel 9) into the first chamber 5. Figure 2 Since the size of the first chamber 5 (shown) is small, a certain amount of backpressure will still be generated in the first chamber 5. Depending on the level of backpressure entering the first chamber 5 and whether the check valve 17 is fully opened, some or no grease in the first chamber 5 will flow through the check valve 17 and into the second chamber 6 along the secondary grease passage 16. When at least the majority of the grease from the first chamber 5 flows through the bypass passage 30, actuation of the handle 2 only requires the force required to advance the second piston 8 against the backpressure in the second chamber 6, since the backpressure on the first piston 7 in the first chamber 5 will be minimal. This makes actuation of the handle 2 from the retracted position to the engaged position more comfortable and easier for the user, since the force required to advance the second piston 8 is relatively small compared to the force required to advance both the first piston 7 and the second piston 8 together. When the grease gun is in high-pressure mode, the additional pressure provided to the second chamber 6 can increase the pressure in the outlet chamber 18 to very high levels (e.g., up to 10,000 psi), which can help clear blockages in the grease outlet 20.

[0068] Once the blockage is cleared and grease can once again flow from the grease outlet 20, the pressure in the outlet chamber 18 will decrease, which will reduce the pressure in the pressure passage 24, thereby causing the pressure on the first end 23A of the valve spool 23 to decrease. Once the pressure decreases so that the force on the first end 23A is less than the force on the second end 23B from the third biasing spring 29, the third biasing spring 29 will push the valve spool 23 to the closed position.

[0069] The following will refer to Figures 14 to 17 A second embodiment of a grease gun is described. Figures 14 to 17 The second embodiment of the grease gun shown includes a Figures 1 to 13 Each of the features described above is provided with the addition of a pressure relief valve 41 and a corresponding passage 43 in which the valve 41 is disposed. As will be appreciated by those skilled in the art, the pressure relief valve may also be implemented as an alternative to the grease gun (e.g., with a Figures 13 to 17 The pressure reducing valve 41 is configured to limit the maximum pressure generated by the grease gun at the outlet 20. If desired, this feature provides a safety measure to protect the hose, coupling, and other mechanical components of the grease gun from overpressure-related failures, and ultimately protect the user from the resulting dangers. Typically, manual grease guns do not include a pressure reducing valve because manual grease guns generally cannot generate sufficient pressure to create a safety issue, so there is no need to limit the pressure generated by manual grease guns.

[0070] In a detailed embodiment, the pressure relief passage 43 is disposed perpendicularly to the first chamber 5 and the second chamber 6. The pressure relief passage includes a first portion 43a, a second portion 43b, and a third portion 43c, which are fluidically connected to each other. The first portion 43a is disposed toward the outlet chamber 18 (i.e., toward the top of the grease gun during use), the third portion 43c is disposed toward the grease barrel 4, and the second portion 43b is disposed intermediate the first and third portions 43a, 43c. The cross-sectional diameter of the second portion 43b is greater than the cross-sectional diameters of the first and third portions 43a, 43c. The second portion 43b is configured to accommodate the valve 41.

[0071] The pressure relief valve 41 is in the form of a spring loaded needle which is biased towards a closed position (see Figure 14 and Figure 15 ), whereby valve 41 is seated on an annular wall 45 surrounding the first portion 43a of the pressure relief passage. Annular wall 45 is formed by the body of the grease gun at the junction between the first portion 43a and the second portion 43b of the pressure relief passage. In the closed position, fluid cannot flow from the first portion 43a of the pressure relief passage to the second portion 43b of the pressure relief passage. In a detailed embodiment, valve 41 includes a tapered protrusion 47 that is configured to extend into the first portion 43a of the pressure relief passage and thereby seat on annular wall 45.

[0072] Figure 16 and Figure 17 The pressure relief valve 41 is shown in an open position. When the grease at the outlet 20 is at a predetermined pressure, the pressure of the grease contained in the first portion 43a of the pressure relief passage causes the valve 41 to overcome its bias and translate within the second portion 43b of the pressure relief passage. In this position, the tapered portion 47 of the valve 41 is retracted (completely or partially) from the first portion 43a of the pressure relief passage, and the valve 41 is spaced apart from the annular wall 45, allowing fluid to flow from the first portion 43a to the second portion 43b of the pressure relief passage. Thus, at the maximum pressure setting, fluid can flow back from the gun's outlet 20 to the grease gun barrel 4.

[0073] In other words, when the pressure at the gun outlet 20 exceeds a threshold value set by the design (e.g., 10,000 psi), the hydraulic thrust on the valve 41 overcomes the biasing force of the spring, and the valve 41 is opened, thereby discharging grease from the outlet 20 into the gun barrel 4. The discharge of grease from the outlet 20 into the gun barrel 4 is accompanied by a pressure drop. When the pressure at the outlet 20 drops, the pressure relief valve 41 closes, and pressure can then be built up again in the gun outlet 20. Therefore, the pressure at the gun outlet 20 is limited to the opening pressure of the pressure relief valve 41.

[0074] The pressure relief valve offers several advantages. The first is end-user safety, as mentioned above. This is because the pressure relief valve limits the maximum pressure the gun can generate, thereby protecting relatively vulnerable components (hoses, fittings, couplings) from over-pressurization and, in turn, protecting the end-user from unexpected situations (high-pressure grease injection). Furthermore, the built-in internal design directs the grease through the valve and directly into the gun barrel. Typically, pressure relief valves on grease guns allow external grease to seep out, which is messy on the grease gun and could potentially create a slip hazard if grease drips onto the ground. Furthermore, the pressure relief valve provides a tactile indication of when maximum pressure has been reached, notifying the end-user that the blockage cannot be cleared by pressure (thus, there is no point in continuing to pump) and that mechanical clearing of the blockage is required. When the valve opens, an audible "click" can be heard, and the user can also feel a sudden drop in force on the trigger.

[0075] The word "comprise" and forms of the word "comprising" used in this description and claims do not limit the claimed invention to exclude any modifications or additions.

[0076] Modifications and improvements to the present invention will be apparent to those skilled in the art and are within the scope of the present invention.

Claims

1. A grease gun comprising: a body connectable to a container configured to store grease, the body defining an elongated first chamber and an elongated second chamber therein, the first chamber extending along a first axis, the second chamber extending along a second axis, the first axis being spaced apart from the second axis, and the second chamber having a smaller cross-sectional area than the first chamber; a first piston and a second piston, the first piston being configured to reciprocate along the first axis within the first chamber, and the second piston being configured to reciprocate along the second axis within the second chamber, the second piston having a smaller cross-sectional area than the first piston; a primary grease passage and a secondary grease passage, wherein the primary grease passage is disposed between the container and the first chamber so that the container can be connected to the first chamber in a fluid communication manner, and the secondary grease passage is disposed between the first chamber and the second chamber and is located midway along the length of the second chamber so that grease can flow from the first chamber into the second chamber; an actuator connected to the body and movable between a retracted position in which grease can flow through the primary grease passage and an engaged position in which grease is restricted from flowing through the primary grease passage, the actuator being configured to reciprocate the first and second pistons when moving between the engaged and retracted positions; as well as A grease outlet is fluidly connected to the second chamber, the grease outlet allowing grease to be discharged from the grease gun.

2. The grease gun according to claim 1, further comprising a first check valve disposed in the secondary grease passage, the first check valve allowing grease to flow from the first chamber into the second chamber.

3. The grease gun according to claim 1 or 2, wherein: The secondary grease passage is disposed midway along the length of the first and second chambers.

4. The grease gun according to claim 1 or 2, wherein: The secondary grease passage extends along a secondary grease passage axis that extends substantially perpendicular to the first axis and the second axis.

5. The grease gun according to claim 1 or 2, further comprising an outlet cavity between the second chamber and the grease outlet.

6. The grease gun of claim 5, further comprising a second check valve in the outlet cavity, the second check valve allowing grease to flow from the second chamber into the outlet cavity.

7. The grease gun according to claim 1 or 2, wherein: The actuator is movable between the retracted position and the engaged position through an intermediate position.

8. The grease gun according to claim 7, wherein: When the actuator is in the intermediate position, grease is restricted from flowing through the primary grease passage.

9. The grease gun according to claim 7, wherein: The first chamber further includes a tertiary grease passage that allows grease to flow into the first chamber when the actuator is in the retracted position or the intermediate position.

10. The grease gun of claim 9, further comprising a third check valve located in the tertiary grease passage, the third check valve allowing grease to flow into the first chamber through the tertiary grease passage.

11. The grease gun according to claim 9, wherein: In use, the primary grease passage and the tertiary grease passage are in fluid communication with the container.

12. The grease gun of claim 1 or 2, further comprising the container, the container being connected to the body.

13. The grease gun according to claim 1 or 2, wherein: The first axis is parallel to the second axis.

14. The grease gun according to claim 7, wherein: The actuator is configured to reciprocate the first piston and the second piston in the same phase when moving between the engaged position, the intermediate position, and the retracted position.

15. The grease gun according to claim 1 or 2, further comprising: a mounting member configured to pivotally connect the actuator to the body; and A first biasing device and a second biasing device are disposed around the first piston and the second piston, respectively, and are each configured to bias the actuator toward the retracted position.

16. The grease gun according to claim 1 or 2, wherein: The actuator includes a first lug and a second lug, wherein the first lug and the second lug are configured to engage the first piston and the second piston, respectively, wherein movement of the actuator from the retracted position toward the engaged position causes the first lug and the second lug to engage the first piston and the second piston, respectively, thereby moving the first piston and the second piston along the first axis and the second axis, respectively.

17. The grease gun of claim 1, wherein: The subject also includes: a spool passage extending along a third axis; a spool movable within the spool passage between an open position and a closed position; and a bypass channel, the bypass channel being in fluid communication with the first chamber and the container through the valve core channel, When the valve core is in the open position, the valve core allows the grease to flow out of the first chamber, and when the valve core is in the closed position, the valve core restricts the grease from flowing out of the first chamber.

18. The grease gun according to claim 17, wherein: In use, when the valve core is in the open position, the valve core allows grease to flow out of the first chamber into the container, and when the valve core is in the closed position, the valve core restricts the grease from flowing out of the first chamber into the container.

19. The grease gun of claim 17, further comprising: a pressure channel disposed at a first end of the valve core channel, the pressure channel being in fluid communication with the outlet chamber; and a third biasing device disposed at a second end of the spool passage, the third biasing device being configured to bias the spool toward the closed position, The increase in pressure in the outlet chamber causes an increase in pressure in the pressure channel and an increase in pressure at the first end of the spool channel, thereby forcing the spool against the third biasing device.

20. The grease gun of claim 19, wherein: The spool is configured to move toward the open position at a predetermined pressure level at a first end of the spool passage.

21. The grease gun of claim 17, wherein: The bypass channel includes a primary bypass channel provided between the first chamber and the valve core channel, and a secondary bypass channel provided between the valve core channel and the container.

22. The grease gun of claim 21, wherein: The primary bypass passage extends along a primary bypass passage axis, and the secondary bypass passage extends along a secondary bypass passage axis, the primary bypass passage axis being offset from the secondary bypass passage axis relative to the spool passage.

23. The grease gun of claim 22, wherein: The primary bypass channel axis is substantially perpendicular to the secondary bypass channel axis and is spaced apart from the secondary bypass channel axis.

24. The grease gun of claim 21, wherein: The valve core channel is connected to the primary bypass channel and the secondary bypass channel, and is arranged between the primary bypass channel and the secondary bypass channel, so that when the valve core is in the open position, grease can flow from the primary bypass channel into the secondary bypass channel via the valve core channel.

25. A grease gun according to any one of claims 21 to 24, wherein The valve core comprises: a first annular ring and a second annular ring, the second annular ring being spaced apart from the first annular ring; and an intermediate section, the intermediate section being disposed between the first annular ring and the second annular ring and being bounded by the first annular ring and the second annular ring, The intermediate section of the spool has a diameter that is smaller than the diameter of the spool passage and the diameters of the first and second annular rings, A communication channel is formed in the area between the middle section of the valve core and the wall of the valve core channel. Regardless of whether the valve core is in the open position or the closed position, the communication channel is fluidically connected to the primary bypass channel.

26. The grease gun of claim 25, wherein: When the spool is in the closed position, the communication passage is not adjacent to the secondary bypass passage, thereby restricting the flow of grease from the spool passage into the secondary bypass passage.

27. The grease gun of claim 25, wherein: When the valve element is in the open position, the communication passage is adjacent to the secondary bypass passage, thereby allowing grease to flow into the secondary bypass passage.

28. The grease gun of claim 25, wherein: The valve core includes a cavity extending through the valve core, the cavity being disposed in the middle section of the valve core to allow grease to flow through the middle section of the valve core and fill the communication passage.

29. The grease gun of claim 1 , further comprising: a decompression channel, the decompression channel being provided between the container and the grease outlet; and A pressure reducing valve is provided in the pressure reducing passage, the pressure reducing valve being configured to open when the pressure of the grease in the outlet reaches a predetermined pressure, thereby allowing the grease to flow from the grease outlet to the container.

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