Background of the Disclosure

It is estimated that 90% of all machine bearings are lubricated by grease. While oil analysis is a widespread tool for monitoring bearing and lubricated component health of important oil lubricated equipment, grease analysis is not generally adopted in a similar manner for important grease lubricated machines. Analyzing a sample of grease taken from a grease- lubricated bearing sometimes is performed to pinpoint the cause of bearing problems in failure analysis. However, the ability to adopt regular and routine grease analysis for important machines has been historically limited by the inability to easily obtain representative samples of the grease in a sufficient quantity to perform cost-effective and meaningful analysis.

Some machine bearings, such as pillow block bearings, may be located on the outside of the machine and may have an exposed layer or thickness of grease surrounding the bearing. A grease sample is obtained by scooping or scraping through the layer of grease. The grease nearest the bearing usually makes the most representative sample, and the scoop or scraper is manipulated to retrieve grease near the bearing. The grease sample, however, may be contaminated by grease retained by the scoop or scraper when moving through the layers of grease away from the bearing.

Other machine bearings may be located in areas of the machine that have limited access. This can make it difficult to manipulate a scoop or scraper in such a way as to obtain only an uncontaminated grease sample taken near those surfaces .

Some machine bearings are housed inside the machine without external access. The housing may incorporate grease inlet openings and grease drain openings associated with the machine bearings. Historically, efforts to obtain grease samples have been made by flowing fresh grease into a grease inlet until grease flows out a drain outlet. While this can sometimes be effective, there is a risk that the bearing may be overfilled with grease- -damaging the bearing or lifting the bearing seals.

Generally, syringe-like devices to obtain grease samples are unsatisfactory due to the physical properties and non- Newtonian flow properties of grease. Wurzbach, US Patent 7,984,661 (which patent has a common inventor with the instant application) discloses a method of obtaining a grease sample in which pressurized grease flows into a tubular housing. The method and related grease sampling device disclosed in the '661 patent have proven to be very useful in obtaining representative grease samples in many different types of operating environments. However, there is an on-going need for other types of grease sampling devices, including a grease sampling device that can extend into a compartment and core a grease sample for removal .

Summary of the Disclosure

Disclosed is a grease sampling device that can extend into a compart and core a grease sample for removal .

An embodiment of the grease sampling device includes a positioning device, a sampling device, and a holder device. The holder device connects the positioning device and the sampling device, with the positioning device spaced from the sampling device.

The sampling device includes a tube and a piston. The tube includes a forward end and an annular interior wall extending along an axis away from the forward end. The piston is in the tube and engages the tube wall. The tube is axially movable with respect to the piston from a first operating position wherein the forward end of the tube is flush with the piston and a second operating position wherein the piston is spaced axially inwardly from the forward end of the tube.

The positioning device includes an outer surface on a forward side of the grease sampling device that, in use, locates the sampling device relative to a supply of grease for which a grease sample is desired. The tube moves relative to the surface of the position device as the tube moves from the first operating position to the second operating position to the tube entering into and coring a grease sample from the supply of grease. The grease sample is retained in the tube when the tube is removed from the supply of grease.

The piston preferably forms a seal with the tube wall that resists the escape of the grease sample from the tube. After retrieving a sample of grease the tube can be moved back towards the first operating position to remove the grease sample from the tube. The grease sample can be transferred from the sampling device to another container for subsequent testing .

The holder device may include releasable fasteners, such as screws or clamps, used to hold the sampling device and the positioning device. The fasteners allow the relative position of the positioning device and the sampling device to be adjusted by the user for a particular sampling environment.

The disclosed grease sampling device is inexpensive, easy to use, and easy to adjust. Using a tube to core the grease enables a representative grease sample to be retrieved from areas in which conventional sampling tools cannot reach or cannot extract grease.

Other objects and features of the disclosure will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawing sheets illustrating one or more illustrative embodiments. Brief Description of the Drawings

Fig. 1 is a front view of an embodiment of the disclosed grease sampling device.

Fig. 2 is a perspective view of a set block of the grease sampling device shown in Figure 1.

Fig. 3 illustrates the grease sampling device shown in Figure 1 positioned against a surface adjacent to a grease access in preparation for obtaining a grease sample.

Detailed Description

Figure 1 illustrates a grease sampling device 4 for obtaining grease samples from within a compartment, enclosure, bearing, or the like. The grease sampling device 4 includes a positioning device 6, a sampling device 8, and a holder device 10 that connects the positioning device 6 with the sampling device 8.

The positioning device 6 positions the grease sampling device 4 in relation to the grease to be sampled. The positioning device 6 includes an elongate position rod 12 carrying a foot 14 on an end of the position rod. The foot 14 may be made from rubber, plastic, or other suitable material. The foot 14 is located on a forward end of the position rod 12 and presents a flat, forward abutment surface 15 in front of the position rod. The surface 15 is located on a forward side of the grease sampling device 4; the illustrated surface 15 is oriented perpendicular to the longitudinal axis of the position rod. The sampling device 8 obtains the grease sample. The sampling device 8 includes an elongate sampling rod or piston rod 16 carrying a disposable piston 18 on a front end of the piston rod, an O-ring 20 mounted on and surrounding the piston rod 16, the O-ring 20 being spaced rearwardly from the piston 18, an elongate "straw" or tube 22 having open ends and an interior annular bore wall sized to sealingly receive the piston 18 and O-ring 20, and a slider ring or annular sleeve 24 that receives the piston rod 16, the sleeve 24 being movable or slidable along the piston rod 16 but unable to fit over the tube 22. The piston rod 16 is received within the tube 22 as shown in Figure 1 and the piston 18 and O-ring 20 allow the tube 22 to move axially with respect to the piston rod 16 while maintaining the sealing relationship.

The piston rod 16 may include an annular groove or channel (not shown) that locates the O-ring 20 axially in place along the piston rod.

The tube 22 in the illustrated embodiment is formed from a constant diameter plastic drinking straw commonly used for drinking water, soft drinks, and the like from a glass or cup. Such drinking straws have a relatively thin wall but have sufficient strength and rigidity for use as an inexpensive, but suitable, tube of the sample device 8. If desired, in other embodiments the tube 22 can be engineered from other materials such as (but not limited to) molded or extruded plastic tubing. To obtain a grease sample after the device 4 has been positioned using the positioning device 6, the tube 22 is extended forwardly beyond the piston 18 for a stroke distance to enter and core a grease sample from the grease as will be described in further detail below.

The position rod 12 and the piston rod 16 may each be made from metal (for example, stainless steel) or other suitable rigid material. In the illustrated embodiment the rods 12, 16 are each about 11 ½ inches (29.2 cm) long and about 0.25 inches (0.64 cm) in diameter. Of course, the length and/or the diameter of the rods 12, 16 may vary in other embodiments and the length and or/diameter of the rods 12, 16 may vary from each other as well.

The holder device 10 positions the sampling device 8 relative to the positioning device 6. The illustrated holder device 10 also enables a user to selectively position the sampling device 8 relative to the positioning device 6 along the length of the position rod 12. The illustrated holder device 10 further cooperates with the sampling device 8 to define the stroke distance of the sampling device 8. In other possible embodiments, the relative position of the sampling device relative to the positioning device may be fixed and not intended to be changed by the user, and/or the stroke distance of the sampling device may be fixed and not intended to be changed by the user. The illustrated holder device 10 includes a back or first holder 26 that holds the positioning device 6 and the sampling device 8 parallel with one another a fixed distance apart, and a front or second holder 28 that both assists in maintaining sealing alignment of the tube 22 with the piston 18 and O-ring 20 during the stroke and cooperates with the slider ring 24 to define the stroke distance of the sampling device 8.

The holder 26 has structure that releasably holds the position rod 12 and the piston rod 16 in a fixed, parallel relationship with each other. When the holder 26 releases its hold on the two rods 12, 16, the relative axial positions of the rods 12, 16 can be adjusted to set a desired axial offset 30 (see Figure 1) of the foot face 15 in the rearward direction from the front of the piston 18.

A portion of the holder 26 is shown in Figure 2. In the illustrated embodiment the holder 26 includes a generally rectangular prismatic set block or body 32 with a pair of parallel through-bores 34, 36, each bore being sized to closely and slidingly receive the position rod 12 and the piston rod 16 respectively. A pair of threaded bores 38, 40 open into respective through-bores 30, 32 and receive externally accessible set screws 42, 44 (see Figure 1) that releasably fasten the rods to the set block.

The front holder 28 is similar in construction and function to the back holder 26 and so only the differences will be discussed. Corresponding elements of the front holder will be given the same reference numbers as used in describing the rear holder. The bore 36 of the front holder is sized to closely receive the tube 22 but allows the tube 22 to slide within the bore. The threaded hole 44 receives a thumb screw 46 rather than a set screw.

Referring back to Figure 1, the slider ring 24 is disposed between the front holder 28 and the back holder 26. The slider ring 24 is sized so as to be unable to fit within the bore 36 of the front holder. When the tube 22 is flush with the piston 18 as shown in Figure 1, the tube 22 extends a distance 48 out of the front holder 28 towards the back holder 26. The distance 48 establishes the stroke distance of the tube 22 as will be described in more detail below.

The centers of the through-bores 34, 36 in the respective holders 26, 28 are the same distance apart from one another so that the holders maintain the position rod 12 and the piston rod 16 parallel with each other a fixed distance apart. In other embodiments the holders can be constructed to permit the distance between the position rod and the piston rod to be user-adjustable to permit a user to selectively change the distance between the position device 6 and the sampling device 8.

The grease sampling device 4 is intended to provide a grease sample having a desired length or core depth generated by the tube 22 being offset from the foot 14 by the offset distance 30 and moving the stroke distance 48 after positioning the grease sampling device 4 using the positioning device 6.

The grease sampling device 4 is assembled with the position rod 12 and the piston rod 16 extending through the respective through-bores of the holders 26, 28, with the foot 30 and the piston 18 on the same (forward) side of the device. The holders' set screws and thumb screw are initially loose to enable axial positioning of the position rod and piston rod to obtain the desired axial offset 30. The front holder 28 is positioned along the tube 22 to obtain the desired stroke length 48. The rear holder 26 is spaced away from the front holder 28 to enable the slider ring 24 to be positioned behind the back end of the tube 22.

The position rod 12, the piston rod 16, and/or the tube 22 may include axially- spaced external indicia (not shown) visible to the user that assists in relative axial positioning of the rods and/or tube with respect to one another or with respect to the holders 26, 28 during assembly.

Figure 1 illustrates the grease sampling device 4 ready for use. The offset 30 in some embodiments may be two inches (5 cm) , and a greater or lesser sampling depth is possible in other embodiments. The tube 22 is flush with the front end of the piston 18. The slider ring 24 is over the piston rod 16 and is located between the back end of the tube and the back holder 26. The holders' set screws and thumb screw are tightened to fix the position rod 12 and the piston rod 16 with respect to the holders 26, 28.

Figure 3 illustrates the grease sampling device 4 with the positioning device 6 against a surface 50 adjacent to an opening in a compartment or grease access 52 in preparation for obtaining a grease sample from a supply or source of grease 54. The foot face 15 is placed against the surface 50. The surface 50 acts as a reference surface that assists in properly positioning and locating the sampling device 8 with respect to the supply of grease. The piston rod 16 and the tube 22 initially extend into the access 52 by a distance determined by the offset 30. To obtain a grease sample, the front holder thumbscrew 48 is loosened and the slider ring 24 is pushed against the back end of the tube 22 to apply a force urging the front end of the tube away from the piston 18. This further advances the tube 22 into the grease access.

The tube moves from a retracted or first operating position shown in solid lines in Figure 3 further into the access to an extended or second operating position shown in phantom in Figure 3 , the forward end of the tube moving in the axial direction further away from the abutment surface 15. Grease enters into the advancing tube through the open front end of the tube .

The front holder 28 obstructs and resists further advance of the slider ring after the slider ring has advanced the tube the stroke length or coring depth 48. The thumb screw is then re-tightened and the device 4 is moved away from the equipment to withdraw the extended tube now containing the grease sample from the grease access.

To remove the grease sample from the tube 22, the thumbscrew 48 is then re-loosened and the tube 22 displaced along the piston rod 16 back to being flush with the piston 18, causing the piston to eject the grease sample from the tube 22. If desired, the grease being ejected from the tube can be transferred into a different receptacle, such as a conventional, standard GREASE THIEF™ grease sampling device available from MRG Labs, York Pennsylvania, USA, for transport to a testing facility.

For taking another grease sample, the tube 22 and piston 18 are preferably disposed of and not reused. The remaining components are cleaned and a replacement tube and piston are installed after cleaning. Methods of removably mounting a piston on an end of a piston rod are known in the art and so will not be described herein.

A preferred feature of the device design is a tight, essentially leak-free, sealing fit between the piston 18 and the tube 22. The piston sealing divides the tube into a forward portion on one side of the piston that includes the open end of the tube and a back portion on the other side of the piston. Since grease is a very cohesive and non-Newtonian material, there is a tendency for a body of grease that has been cored to slump back out of the tube after it has been received into the tube 22. However, a good fit of the piston or a good seal of the piston with the tube interior wall will resist air from entering behind the piston, generating a suction force that exceeds the cohesive forces of the grease and resists slumping of the grease out of the tube, resulting in a more full cored draw of grease.

A tight fit of the piston in the tube also ensures that the depth intended to be sampled is included in the tube when withdrawn, and not partially left behind -- which could otherwise affect the representative nature of the sample. The sealing fit between the piston and tube can be implemented or supplemented in some possible embodiments by an additional sealing piston, a sealing O-ring (as in the illustrated embodiment) or other sealing structure behind the piston and in contact with the bore of the tube, or combinations thereof. The sealing feature may include a piston lip design that can accommodate varying tube inner bore wall sizes or irregularities, within expected manufacturing tolerances of the tube .

In possible alternative embodiments the piston lip is an annular lip that presses against the bore wall of the tube and the suction force urges the piston lip against the tube bore wall. Such piston lip structures are known and can be adapted for use with the disclosed grease sampling device.

In possible embodiments of the holder device 10, the fastening structure connecting the positioning device with the sampling device can be formed as clamps or other conventional holding structures that releasably hold elongate members . The clamps or other holder structures could be movably mounted in forming the holder device 10 to enable the distance between the positioning device 6 and the sampling device 8 to be user- adjustable .

In possible embodiments of the sampling device 8, the slide ring 24 can be eliminated. The tube 22 may include a radially enlarged back end portion 56 (see Figure 1) that establishes the stroke distance of the tube.

Although the illustrated embodiment shows the piston 18 spaced farther from the front holder 28 than the foot 14, the grease sampling device 4 can be adjusted prior to use to place the piston 18 the same distance from or closer to the front holder 28.

While one or more embodiments have been disclosed and described in detail, it is understood that this is capable of modification and that the scope of the disclosure is not limited to the precise details or embodiments set forth but includes modifications obvious to a person of ordinary skill in possession of this disclosure, including (but not limited to) changes in material selection, size or dimensions, operating ranges (temperature, volume, displacement, stroke length, concentration, and the like) , and also such modifications as fall within the following claims.