Patent ID: 12215823

DETAILED DESCRIPTION

FIG.1is a schematic diagram of lubrication system10, a system that receives, stores, and supplies lubricant to machinery. Lubrication system10includes control12, lubricant pump14, power source16, lubrication line18, lubricant injectors20, supply line22, and machinery24. Lubricant pump14includes wet portion26, dry portion28, reservoir housing30, pump base32, pump element(s)34, heaters36, and thermal switch38.

Control12is connected to lubricant pump14. Power source16is connected to lubricant pump14to provide power to various components of lubricant pump14. For example, power source16can be an electrical grid, a generator, a battery, or of any other type suitable for providing power to lubricant pump14. In some examples, power source16can be configured to generate direct current (DC) power. In other examples, power source16can be configured to generate alternating current (AC) power.

Lubricant is stored in wet portion26of lubricant pump14. Lubricant is not present in dry portion28. Reservoir housing30and pump base32define wet portion26. Pump base32defines dry portion28. Pump elements34extend into reservoir housing30and are fluidly connected to wet portion26to receive lubricant from wet portion26. Lubrication line18extends from pump14and is connected to lubricant injectors20. Supply line22extend from lubricant injectors20and is connected to machinery24. Heaters36are disposed in wet portion26proximate pump elements34. Thermal switch38is disposed in dry portion28within pump base32. As such, thermal switch38is not exposed to the lubricant within wet portion26. Thermal switch38is electrically connected to heaters36to control activation and deactivation of heaters36based on the ambient temperature at thermal switch38.

Lubrication system10is a dedicated lubrication assembly for use with lubricated machinery24such as pumps, pistons, seals, bearings, and/or shafts. Reservoir16stores lubricant for distribution to lubricant injectors20, and lubricant injectors20provide set amounts of lubricant to machinery24at specific locations. Control12activates pump elements34, such as by activating a motor that drives pump elements34, to cause pump elements34to draw lubricant from reservoir16and drive the lubricant downstream through lubrication line18.

Heaters36are disposed in wet portion26and are exposed to the lubricant within wet portion26. Each heater36receives power from power source16and is configured to heat the local area at each pump element34to reduce the viscosity of the lubricant at pump element34. In some examples, heaters36can be self-regulating heaters where the temperature generated by the heater36is regulated by the materials comprising the heater36. As such, heaters36can be configured to generate heat up to a maximum temperature. Heating the lubricant and thereby reducing the viscosity of the lubricant facilitates efficient, effective pumping by pump elements34.

Thermal switch38is electrically connected to heaters36. Thermal switch38controls activation and deactivation of heaters36. Thermal switch38is configured to electrically connect heaters36to power source16, thereby activating heaters36, when the temperature at thermal switch38falls below a threshold. Thermal switch38is configured to electrically disconnect heaters36from power source16, thereby deactivating heaters36, when the temperature at thermal switch38rises above the threshold. In some examples, thermal switch38can control activation and deactivation of heaters36based on different thresholds. For example, thermal switch38can activate heaters36when the temperature reaches or falls below a lower threshold and can deactivate heaters36when the temperature reaches or rises above an upper threshold. Thermal switch38can be of any type suitable for controlling activation and deactivation of heaters36based on the temperature. As discussed above, thermal switch38is disposed in dry portion28such that thermal switch38is not exposed to the lubricant. Thermal switch38controls activation and deactivation of heaters36based on air temperature, not the temperature of the lubricant. It is understood, however, that thermal switch38can, in some examples, be exposed to the lubricant to control heaters36based on the actual lubricant temperature.

FIG.2Ais an isometric view of lubricant pump14.FIG.2Bis a cross-sectional view of lubricant pump14taken along line B-B inFIG.2A.FIGS.2A and2Bwill be discussed together. Lubricant pump14includes reservoir housing30, pump base32, pump elements34, heaters36, ricer plate40, drive42, follower plate43, and follower spring45. Pump base32includes upper wall44, pump ports46, recesses48, and power port50. Pump element34includes pump body52, piston54, return spring56, and check valve58. Pump body52includes inlet60(shown inFIGS.3A and3B) and outlet62. Drive42includes motor64, drive shaft66, and cam68.

Lubricant pump14is configured to store and supply lubricant, such as grease or oil, for application to machinery. Reservoir housing30is mounted on pump base32. Reservoir housing30and pump base32define the reservoir70within which lubricant is stored. Follower plate43is disposed in reservoir70and is configured to rise and fall within reservoir70along with the level of the lubricant in reservoir70. Follower spring45biases follower plate43towards the top surface of the lubricant. Ricer plate40is mounted on pump base32and is disposed in reservoir housing30. The lubricant flows through ricer plate40prior to encountering pump elements34. Ricer plate40can break up the lubricant to ease flow into pump elements34. While lubricant pump14is described as including a ricer plate40, it is understood that some examples of lubricant pump14do not include a ricer plate40.

Pump ports46extend through a portion of pump base32. In the example shown, pump ports46extend into pump body52at a location between ricer plate40and upper wall44. Upper wall44of pump base32defines a lower boundary of the reservoir70. Upper wall44isolates the wet components of lubricant pump14, which are those exposed to the lubricant, from the dry components of lubricant pump14, which are those not exposed to the lubricant. Recesses48are formed in the portion of upper wall44facing the lubricant. Power port50extends into pump base32and is configured to receive an electrical power cord. In some examples, lubricant pump14can be powered by direct current (DC) power. In other examples, lubricant pump14can be powered by alternating current (AC) power.

Pump elements34are mounted to pump base32at pump ports46. For each pump element34, pump body52is secured within pump port46and extends through pump port46into reservoir70. For example, pump body52can include external threading configured to interface with internal threading within pump port46. It is understood, however, that pump body52can be secured in pump port46in any desired manner. While lubricant pump14is shown as including two pump elements34, it is understood that some examples of lubricant pump14include a single pump element34and other examples of lubricant pump14can include more than two pump elements34.

Check valve58is disposed in pump body52. Piston54extends out of pump body52and into reservoir70. Inlet60extends through pump body52at a location upstream of check valve58. Outlet62is disposed on an opposite side of check valve58from inlet60. Return spring56is disposed on an exterior of pump element34and is configured to drive piston54through a suction stroke.

Drive42is configured to power pump element34. Motor64is mounted in pump base32. Drive shaft66extends from motor64and through upper wall44. Motor64can be of any desired configuration for driving drive shaft66, such as an electric motor, a pneumatic motor, or a hydraulic motor, among other options. Cam68is eccentrically mounted on drive shaft66. During operation, motor64drives rotation of drive shaft66. Drive shaft66rotates and drives rotation of cam68. Cam68is configured to push piston54of pump element34through a pumping stroke.

Heaters36are disposed in reservoir70on the wet side of upper wall44. Heaters36are supported by pump base32. Heaters36are mounted within recesses48such that heaters36are disposed below pump ports46and thus below pump body52of pump element34. As such, pump body52extends over heater36when pump element34is mounted to pump base32. Heater36is configured to increase the local temperature of the lubricant at pump element34.

Heater36is configured to heat the local area around heater36, including pump element34and the lubricant surrounding pump element34. However, heater36does not heat the entire pump base32or the full volume of reservoir70. In one example, heater36includes a self-regulating heater. For example, heater36can be a positive temperature coefficient (PTC) heater. A PTC heater is a self-regulating heater where the temperature generated by the heater36is regulated by the materials comprising the heater. The resistivity of the material increases with increasing temperature. As such, the PTC heater will produce high power when it is cold and will rapidly heat to a limit temperature. Due to the increasing resistivity as the temperature increase, the PTC heater is self-limiting in that it will not heat beyond the limit temperature. In one example, heaters36are PTC heaters having a limit temperature of about 65-degrees C. (about 150-degrees F.).

During operation, lubricant is stored in reservoir70prior to application. Motor64drives rotation of drive shaft66. Drive shaft66drives rotation of cam68. Cam68drives piston54forward within pump body52through a pumping stroke. The piston54increases the pressure within pump body52and drives the pressurized lubricant through check valve58and downstream out of pump element34through outlet62. The lubricant flows from outlet62to an application point, such as a lubricant injector.

The cam68rotates away from pump element34, removing the pushing force from piston54and begins to drive the piston54of the other pump element34through a pumping stroke. Return spring56pushes piston54through a suction stroke, where piston54is drawn through pump body52away from check valve58. Pushing piston54through the suction stroke creates a void in pump body52between check valve58and the end of piston54disposed within pump body52. The void continues to expand until the end of piston54reaches inlet60. As the end of piston54passes inlet60, the lubricant is drawn into pump body52by the void, thereby refilling pump element34for the next pumping stroke.

As the environmental temperature decreases, the lubricant becomes more viscous and does not flow as easily as at higher temperatures. In some cases, lubricant pump14is required to operate at environmental temperatures reaching 40-degrees C. below zero (negative 40-degrees) (about 40-degrees F. below zero). For example, lubricant pump14can be utilized in a wind turbine exposed to those harsh environmental temperatures.

Heaters36are disposed in lubricant pump14to ensure flow of lubricant even at very low environmental temperatures. A single one of heaters36will be discussed in detail, but it is understood that the discussion is applicable to both heaters36in lubricant pump14. Heater36is disposed in recess48formed in pump base32. Heater36is thus supported by pump base32and disposed between pump base32and pump body52. Heater36is exposed to the lubricant within reservoir70.

As discussed above, heater36can be a self-regulating heater such that the material properties of heater36limit the maximum temperature achievable by heater36. For example, heater36can be a PTC thermistor. Heater36is electrically powered and is configured to heat the local area at pump element34. Heater36increases the temperature of the lubricant surrounding pump element34and can increase the temperature of pump element34itself. In some examples, heater36is sized to raise the temperature of the lubricant about 10-degrees C. (about 50-degrees F.) relative to the other lubricant in reservoir70. Increasing the local temperature reduces the viscosity of the lubricant at pump element34, ensuring that pump element34can draw the lubricant into pump body52during the suction stroke and drive the lubricant downstream through outlet62during the pumping stroke. However, heaters36are not configured to heat the full volume of the lubricant within reservoir. In addition, heaters36directly heat the lubricant, as heaters36are exposed to the lubricant. Heaters36are not configured to heat other elements, such as pump base32or reservoir housing30, that then transfer the heat from heaters36to the lubricant. It is understood, however, that heaters36can be enclosed within a local enclosure without deviating from the teachings of this disclosure.

Lubricant pump14provides significant advantages. Heaters36are disposed in reservoir70and heat the lubricant residing proximate pump element34. Heaters36increase the local temperature at pump element34, thereby decreasing the viscosity of the lubricant residing around pump element34. Reducing the viscosity allows the lubricant to flow more easily, thereby ensuring that pump element34can effectively pump the lubricant even at very low temperatures. Providing local heating, as opposed to heating the full volume of lubricant in reservoir70, consumes a small amount of power, allowing lubricant pump14to be powered by DC power and efficiently pump the lubricant. Moreover, heaters36being self-regulating heaters, such as PTC thermistors, allows heaters36to provide effective heating while eliminating the risk of overheating or excessive power consumption.

FIG.3Ais a top elevational view of lubricant pump14with reservoir housing30removed.FIG.3Bis a top isometric view of lubricant with reservoir housing30removed.FIGS.3A and3Bwill be discussed together. Pump base32, pump element34, heaters36, drive42, top plate72, and plug74of lubricant pump14are shown. A portion of ricer plate40is also shown inFIG.3B. Ricer plate40includes pegs76. Drive shaft66and cam68(FIG.3A) of drive42are shown. Only one pump element34is shown inFIG.3B. A pump port46(FIG.3B) is shown without a pump element34mounted in the pump port46. Pump body52, piston54and return spring56of pump element34are shown. Inlet60and outlet62of pump body52are shown. Each heater36includes heating element78and power lines80.

Pump base32houses the various power components of lubricant pump14, such as drive42. Drive shaft66of drive42extends through upper wall44of pump base32into reservoir70(best seen inFIG.2B). Cam68is mounted on drive shaft66. Pump element34is mounted to pump base32and extends through a first pump port46through pump base32. A second pump port46is shown inFIG.3B. Pump body52is at least partially disposed on the interior of pump base32, such that pump body52is disposed within the lubricant stored in reservoir70. Inlet60extends through a portion of pump body52within the interior of pump base32. Inlet60provides a pathway for lubricant to enter pump body52. Outlet62extends into a portion of pump body52on the exterior of pump base32. Outlet62provides a pathway for lubricant to exit pump body52. Piston54is disposed within pump body52and is reciprocate within pump body52to drive the lubricant. Return spring56extends between pump body52and an end of piston54disposed outside of pump body52. Return spring56is configured to drive piston54through a suction stroke.

Heaters36are mounted within pump base32and are configured to heat the local area about each pump element34. Heating elements78are supported by pump base32. Heating elements78are disposed between upper wall44and pump body52. Power lines80extend from each heating element78through plug74. Plug74separates the wet portions of lubricant pump14from the dry portions within pump base32. Top plate72is attached to pump base32over plug74. Top plate72is configured to retain plug74in pump base32to prevent plug74from inadvertently loosening, which could allow lubricant to leak between the wet portion and the dry portion. Power lines80provide power to heating elements78.

Ricer plate40is disposed in pump base32and secured to pump base32. Pegs76project downward from a bottom side of ricer plate40towards upper wall44of pump base32. Pegs76interface with, or are disposed adjacent to, a top side of each heating element78. Pegs76retain heating elements78within recesses48(FIG.2B) in pump base32during operation. Pegs76prevent heating elements78from displacing vertically while recesses48prevent heating elements78from displacing laterally. While heating elements78are shown as secured within recesses48by pegs76, it is understood that heating elements78can be secured in any desired manner. For example, retainers, such as screws or bolts, can extend into pump base32proximate an edge of heating element78. A flange, such as a washer or integral flange, can extend from the retainer over the edge of heating element78to secure heating element78in place.

During operation, drive shaft66rotates and drives cam68. Cam68pushes piston54through a pumping stroke and return spring56pushes piston through a suction stroke. Lubricant is drawn into pump body52through inlet60during the suction stroke. Lubricant is driven out of pump body52through outlet62during the pumping stroke.

The viscosity of the lubricant increases as the environmental temperature around lubricant pump14decreases. Heaters36are configured to increase the local temperature of the lubricant at pump element34to decrease the viscosity of the lubricant and ensure efficient pumping by pump element34.

Heating elements78receive power through power lines80. As discussed above, heating elements78can be self-regulating heaters configured to heat to a maximum temperature. Heating elements78do not heat the entirety of the lubricant within reservoir70, instead heating the local lubricant around pump element34. Locally increasing the temperature at pump element34ensures that the lubricant around pump element34, which is the first lubricant that will enter pump body52through inlet60is sufficiently fluidic that the lubricant flows into and through pump element34. Moreover, by only heating the local area around pump element34, heaters36consume relatively little power and can be operated with a DC power source.

FIG.4is a bottom isometric view of pump base32. Pump base32, a portion of pump element34, thermal switch38, motor64of drive42(best seen inFIG.2B), power lines80of heaters36(best seen inFIGS.3A and3B), and plug74are shown. Upper wall44and power port50of pump base32are shown.

Power port50is disposed on a side of pump base32and is configured to receive a power cord from a power source, such as power source16(FIG.1). Power lines80extend from the power source to heating elements78(best seen inFIGS.3A and3B). Power lines80extend to heating elements78through plug74in upper wall44. In some examples, power lines80for the multiple heating elements78can combine into single wires to pass through plug74. Power lines80are connected to thermal switch38. Thermal switch38is mounted in the dry portion of pump base32such that thermal switch38is separated from and does not contact the lubricant.

Thermal switch38is configured to control activation and deactivation of heating elements78. Thermal switch38is configured to close, connecting heating elements78to the power source, when the ambient temperature around thermal switch38reaches a lower threshold temperature. Thermal switch38is configured to open, disconnecting heating elements78from the power source, when the ambient temperature around thermal switch38reaches an upper threshold temperate. For example, thermal switch38can be a bimetallic snap disc thermostat, among other options.

Thermal switch38controls activation and deactivation of heating elements78to ensure that heating elements78heat the lubricant when temperatures are low enough to require heating of the lubricant, but that heating elements78are not active, and thus not consuming power, when temperatures are sufficiently high. In one example, the lower threshold is between about 0-degrees C. (about 32-degrees F.) and about 10-degrees C. below zero (about 14-degrees F.). More particularly, the lower threshold can be about 5-degrees C. below zero (about 23-degrees F.). In one example, the upper threshold is between about 4-degrees C. (about 39-degrees F.) and about 10-degrees C. (about 50-degrees F.). More particularly, the upper threshold can be about 7-degrees C. (about 45-degrees F.). It is understood, however, that thermal switch38can be configured to have any desired lower threshold and upper threshold.

The lower threshold and upper threshold can be based on the power of motor64and the properties of the lubricant being pumped, among other options. The lower threshold is set to prevent the viscosity of the lubricant from rising to an undesired level that could inhibit pumping. The upper threshold is set where the viscosity of the liquid is sufficiently low such that additional heating is not needed to facilitate flow of the lubricant into pump element34. While thermal switch38is described as having a lower threshold and an upper threshold, it is understood that thermal switch38can be configured to have a single activation temperature. As such, thermal switch38can connect heating elements78to power when the temperature is at or below the activation temperature and can disconnect heating elements78from power when the temperature is at or above the activation temperature. Whether thermal switch38is open or closed at the activation temperature is based on the particular configuration of thermal switch38.

Thermal switch38is disposed in pump base32such that thermal switch38is not exposed to the lubricant within lubricant pump14. Thermal switch38controls activation and deactivation of heating elements78based on the air temperature at thermal switch38. Disposing thermal switch38in pump base32isolates thermal switch38from the local temperature increase caused by heating elements78. Isolating thermal switch38prevents undesired cycling of heaters36on and off as the local temperature at heaters36increases and decreases.

During operation, power is provided to lubricant pump14. Motor64powers pump element34to cause pumping by pump element34. Thermal switch38remains open, disconnecting power from heating elements78, until the temperature at thermal switch38falls to the lower threshold temperature. Thermal switch38closes when the temperature reaches the lower threshold, thereby connecting power to heating element78. Heating elements78generate heat and provide local heating of the lubricant and pump element34. Heating elements78continue to generate heat so long as thermal switch38is closed. As discussed above, however, heaters36are self-regulating such that heating element78cannot generate heat above a threshold temperature.

Thermal switch38continues to provide power to heating elements78until the temperature at thermal switch rises to the upper limit. Thermal switch38opens when the temperature reaches the upper threshold, thereby disconnecting power from heating element78, thereby shutting down heating element78.

Thermal switch38provides significant advantages. Thermal switch38is mounted in the dry portion of pump base32such that thermal switch38is not exposed to the lubricant. As such, thermal switch38does not cycle open and closed due to a local temperature rise; instead, thermal switch38controls heating based on air temperature. Thermal switch38activates heating elements78when the temperature reaches the lower threshold, ensuring that heating elements78are powered only when needed to decrease the viscosity. Thermal switch38deactivates heating elements78when the temperature reaches the upper threshold, preventing unnecessary heating by heating elements78.

FIG.5is a partial quarter-sectional view of a portion of lubricant pump14. Pump base32; ricer plate40; motor64, drive shaft66, and cam68of drive42; top plate72, and plug74are shown. Upper wall44of pump base32is shown. Upper wall44includes plug bore82, which includes sidewall84. Power lines80of heaters36(best seen inFIGS.3A and3B) are shown. Plug74includes upper face86, lower face88, edge90, and wire bores92.

As discussed above, heaters36are configured to heat the local area surrounding pump elements34(best seen inFIGS.2B and3A). Power lines80extend from heating element78and into a dry portion of pump base32. Power lines80are configured to provide power to heating elements78(best seen inFIGS.3A and3B) to power heating elements78.

Plug bore82extends through upper wall44between. Plug bore82provides an opening for power lines80to extend from the wet portion of lubricant pump14into the dry portion of lubricant pump14and then to thermal switch38(FIG.4). Plug74is mounted in plug bore82and provides a fluid seal at plug bore82to prevent the lubricant from flowing between the wet portion and the dry portion. Wire bores92extend through plug74between upper face86and lower face88. Wire bores92provide passages for power lines80to extend through plug74. Wire bores92can be sized such that lubricant cannot pass through wire bores92even when a power line80is not disposed in the wire bore92.

Plug74is frustoconical such that edge90is tapered between upper face86and lower face88, with upper face86having a larger diameter than lower face88. Plug bore82is contoured to mate with plug74. As such, sidewall84of plug bore82is also tapered between wet portion26and dry portion28. The mating tapered profiles of plug74and plug bore82ensure a fluid tight seal is formed between plug74and plug bore82. Top plate72is secured to pump base32and extends over upper face86of plug74to retain plug74within plug bore82.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.