POSITIVE DISPLACEMENT PUMP
SPECIFICATION
FIELD OF THE INVENTION
This invention relates generally to the field of pumps, more particularly, to positive displacement pumps and associated lubrication reservoirs for lubrication.
BACKGROUND OF THE INVENTION
Conventional lubricator devices for delivering lubricant to a particular point, gas-operated or mechanically operated, do so by generating an output pressure of approximately 100-150 psi. Most of these lubricator devices operate by pushing against the entire lubricant surface of a bellows-type grease container, that is releasably secured inside the pump assembly itself, using a ratchet or jack shaft type operation or pressurized gas generators.
Some of the problems with these conventional lubricator devices is that the entire lubricant surface is being pushed against, and as such, the operator cannot determine just how much grease has been delivered; and since the grease container is disposed inside the pump assembly the operator also cannot determine when to replace the grease container. In addition, many of these conventional lubricator devices are temperature sensitive, i.e., they tend to not work properly at temperatures above and below room temperature. This complicates electronically-driven pumps where electronic timers are used-should the temperature drop and the grease become more viscous, the pump runs only for the time specified regardless of the amount of grease delivered; if the power source comprises batteries, the batteries themselves are temperature sensitive and at low temperatures may not supply the proper current to drive the pump through the timed sequence. The result is a temperature-sensitive lubricating device that delivers a varied amount of lubricant.
The following U.S. patents concern mechanically-controlled lubrication pumps. U.S. Pat. No.2,792,911 (Harter) discloses a divisional lubricant feeder for transmitting lubricant from a central station to a plurality of lubricating devices. In particular, the device comprises a plurality of blocks of the same size but having internal cylinders of respectively different sizes to deliver respective amounts of lubricant. U.S. Patent No. 2,856,024 (Thomas) discloses a lubricant pump for use in a centralized
lubrication system. U.S. Patent No. 2,899,017 (Liljemark) discloses a lubricant pump that utilizes an external motor for driving a cam element to activate the pump. U.S. Patent No. 3,071 ,208 (Rasch et al.) discloses a mechanical timer for use with a lubricating device (187) on a vehicle; power to the timer and the lubricating device is provided by the vehicle's ignition switch. U.S. Pat. No. 3,461 ,990 (Stripp et al.) discloses a trailer lubrication system whose pump is activated when the trailer suspension is vertically displaced. U.S. Pat. No. 3,487,892 (Kiefer) discloses a pump that permits the volume of output lubricant to be varied by varying the length of the pumping element stroke and by varying the frequency of the movement of the pumping element. U.S. Pat. No. 4,006,797 (Keske) discloses a cam actuated lubrication pump that utilizes an inverted cup-shaped member having a cam follower that is reciprocally mounted on an upstanding cylindrical member, the latter of which comprises an annular piston that defines a pair of isolated and expansible first and second chambers. U.S. Pat. No. 4,113,061 (Peaster) discloses an automatic lubricator that uses service gun pressure to provide the lubrication pressure by first trapping the pressure in the device and then slowly feeding out the lubricant to the lube points. U.S. Pat. No. 4,527,965 (Markley) discloses a lubrication means for cyclically discharging lubricant into a fluid working chamber by using a rotary piston. U.S. Pat. No. 4,758,100 (Gϋttinger) discloses an automatic lubricant metering device that comprises a housing having an internal piston that conveys lubricant through a feeder line to a lubricating location of a revolving shaft and wherein the advance of the piston is a function of the abrasion of the pin that drives the piston. U.S. Patent No. 4,801 ,051 (Lewis et al.) is directed to a flow micro-adjustment assembly for use with a dispensing device (e.g., a lubricating pump). U.S. Pat. No. 4,893,697 (Tosi) discloses an injection lubricator which includes a lubricant pump having a pumping piston actuated by a pneumatic pulse to deliver a pulse of lubricant. U.S. Patent No. 5,002,156 (Gaunt) discloses a positive displacement pump that utilizes a lubricating piston that delivers one pulse of lubricant for air pulse input supplied from an air pulse source. U.S. Pat. No. 5,178,233 (Nesseth) discloses a continuous lubrication method and apparatus whereby a memory retentive material when inserted within a lubricant reservoir, compresses when initially subjected to lubricant pressure and later expands back to its original shape as lubricant seeps from the reservoir.
The following U.S. patents disclose electrically-controlled lubricating pumps. U.S. Pat. No. 4,836,334 (Vermeiren et al.) discloses a lubricating device that uses a timer for delivering a given quantity of lubricant. U.S. Pat. No. 5,402,913 (Graf) discloses an electrically-controlled lever for controlling a pump to deliver a particular quantity of lubricant; the control may comprise a source of electrical pulses with adjustable pulse duration with or without a cyclically-operated timing relay or can be any duration regulated directly or indirectly in response to the speed of an engine or the speed of a vehicle. U.S. Pat. No. 5,404,966 (Yang) discloses an automatic lubricating device that comprises a container filled with lubricant, a slidable piston fitted within a safety means, a frame welded onto the container, a gas generating means fixed onto the frame, a lubricant outlet and an electronic circuit; when the piston is at the top dead center, the space defined between the bottom of the gas generating member and the upper side of the piston is substantially smaller compared to the rate of gas generation so that prompt initiation of the lubrication is possible. U.S. Pat. No. 5,509,501 (Damme) discloses a battery-operated, electronically-driven lubricating devices. However, unlike the present invention, as is discussed below, the devices disclosed in U.S. Pat. No. 5,509,501 (Damme) do not control the flow rate of the grease since the discharge of grease is dependent upon the pressure developed by the spring.
The following U.S. patents concern lubrication reservoirs that are coupled to the point to be lubricated. U.S. Patent Nos. 2,011 ,616 (Clarke); 2,294,673 (Prete et al.); 2,857,020 (Otto); 2,985,256 (Simmons et al.); 3,430,731 (Satzinger); 3,498,413 (Krieger); 3,739,877 (Oliveri); 3,842,939 (Satzinger); 5,303,800 (Persson). U.S. Patent No. 5,449,050 (Persson et al.) discloses a grease cup that cooperates with a valve for dispensing lubricant.
Therefore, it is believed that a need exists for a positive displacement pump that is a stand-alone, self-contained unit that can automatically provide an output as high as 400 psi for delivering a predetermined amount of lubricant (e.g. , grease or oil) from an ancillary reservoir that is directly coupable to the pump and that can operate over a wide temperature range.
OBJECTS OF THE INVENTION
Accordingly, it is the general object of this invention to provide an apparatus which addresses the aforementioned needs.
It is a further object of this invention to provide a positive displacement pump for delivering a predetermined amount of lubrication automatically.
It is yet another object of this invention to provide a positive displacement pump for delivering a predetermined amount of grease or oil.
It is still yet a further object of this invention to provide a positive displacement pump that is a stand alone, self contained unit having the ability to automatically lubricate a single point.
It is even yet a further object of this invention to provide a positive displacement pump that is a stand alone, self contained unit having the ability to automatically lubricate multiple points simultaneously.
It is even yet a further object of this invention to provide a stand alone, self contained positive displacement pump that can generate as much as 400 psi at the output.
It is even another object of this invention to provide a stand alone, self contained positive displacement pump that operates on a lube cycle whose period is adjustable by the end user.
SUMMARY OF THE INVENTION These and other objects of this invention are achieved by providing an apparatus for automatically dispensing a predetermined amount of lubricant over a wide temperature range. The apparatus comprises a pump having an inlet port and an outlet port and further comprises a piston movable within a cylinder that is in fluid communication with the inlet port and the outlet port. The piston, cylinder, inlet port and outlet port are contained within a housing. The apparatus further comprises an ancillary lubricant reservoir coupled to the inlet port. The apparatus further comprises means, contained within the housing and coupled to the piston, for positively controlling the dispensing of the predetermined amount of lubricant from the inlet port to the outlet port. The apparatus further comprises power means, contained within
the housing, for powering the means for positively controlling the dispensing of the predetermined amount of lubricant to permit stand-alone operation of the apparatus. These and other objects of this invention are achieved by providing a method for automatically dispensing a predetermined amount of lubricant over a wide temperature range. The method comprises the steps of: (a) providing a lubricant reservoir that is in fluid communication with a cylinder containing a piston and whereby the reservoir, cylinder and piston are located at a site; (b) automatically driving the piston in a first direction to withdraw a predetermined amount of lubricant from the reservoir through a first check valve; (c) automatically driving the piston in a second direction using positive control to dispense the predetermined amount of lubricant out of the cylinder through a second check valve; (d) repeating the steps b and c in accordance with a user-adjustable lubrication cycle; and (e) providing power means for at the site for supporting steps b-e to permit stand-alone operation of the piston.
DESCRIPTION OF THE DRAWINGS
Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
Fig. 1 is a block diagram of the present invention;
Fig. 2 is a side view of the present invention;
Fig. 3 is a side view of a grease lubricator reservoir showing an internal piston partially compressed;
Fig. 4 is a side view of an oil lubricator reservoir;
Fig. 5 is an isometric view of the pump assembly with the lid removed;
Fig. 6 is a cross-sectional view of the pump taken along line 6-6 of Fig. 5;
Fig. 7 is a bottom view, partially cut-a-way, of the gear reduction assembly taken along line 7-7 of Fig. 5;
Fig. 8 is top view of the pump assembly taken along line 8-8 of Fig. 5 with the pump shown in phantom;
Fig. 9 is a timing diagram of the microswitch and the DC motor; and
Fig. 10 is an electrical schematic of the PCB timer.
DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION Referring now in greater detail to the various figures of the drawing wherein like reference characters refer to like parts, a positive displacement pump (hereinafter "PDP") constructed in accordance with the present invention is shown generally at 20 in Fig. 1.
The PDP 20 is a self contained piston discharge pump actuated by a DC motor driven cam. In particular, the PDP 20 comprises a pump assembly 22 and a lubricant reservoir 24. The pump assembly 22 basically comprises a piston 26, an associated cylinder 28, biasing member 30, an inlet check valve 32, an outlet check valve 34, a piston cam 36, a position cam 38, a microswitch 40, a PCB (printed circuit board) timer 42, a D.C. motor 44, a gear reduction transmission assembly 46 and a power pack 48. The piston 26, cylinder, biasing member 30, input check valve 32 and output check valve 34 define the pump 50.
The lubricant reservoir 24 is a disposable, transparent, spring fed canister (LUBESITE model 404) that is filled with grease, e.g., lithium-based N. L.G.I. No. 1 grease. The reservoir 24 is releasably coupled to the pump assembly 22 at its input. The grease 56 is pushed out of the reservoir 24 by operation of a biasing means 58 and a piston 60, as well as by a partial vacuum created internally by the pump assembly 22, as will be discussed later. As can be seen more clearly in Fig. 3, the reservoir 24 comprises a threaded portion 62 (Fig. 4) that is received by a corresponding threaded inlet port 64 (Fig. 5) of the pump assembly 22.
The pump assembly 22 (Fig. 2) also comprises an outlet port 65 (which is also threaded but not shown) to which there is releasably coupled (e.g., a threaded engagement) a manifold 52. Releasably coupled to the manifold 52 are a plurality of Bijur flow control fittings; each of these fittings comprise Bijur control units (e.g. , CJB- 5 Bijur control units) 54A, 54B and 54C for evenly distributing the predetermined amount of grease (e.g., 2 cc) to multiple lube points (not shown) via respective tubing 55A, 55B and 55C. It should be understood that a single fitting could also be directly coupled to the pump assembly 22 output without the need for the manifold 52 if only a single lube point is to be connected to the PDP 20.
Fig. 5 shows the pump assembly 22 with its lid 66 removed once a pair of screws 68A and 68B are removed. The pump assembly 22 basically comprises a housing 69 (Figs. 2 and 5) made of high-impact ABS plastic; the pump 50 (Fig. 1 ) is made of a lightweight, durable material such as aluminum. The PCB timer 42 can be seen positioned in the housing 69 and includes an 8-position DIP switch 70. Discharge cycles and timing (to be discussed later) are controlled by the PCB timer 42 which is set by the end user via the DIP switch 70 for the desired discharge rates. The PCB timer 42 is supported within the housing 69 by a pair of sleeves (only one 72 of which is visible in Fig. 5); a pair of screws 74A and 74B pass through the sleeves and releasably secure the PCB timer 42 to an internal portion (not shown) of the pump housing 69.
The power pack 48 comprises four AA batteries (not shown); the battery connector 76 can be seen in Fig. 5 as well as a top portion of the power pack 48.
As shown in Fig. 6, the piston 26 is actuated by the single lobe piston cam 36 which is driven by the micro D.C. motor 44 (e.g., Douglas International, Inc. M752-F 6VDC motor or F3686VDC motor, 3000 rpm) via a 500: 1 gear reduction transmission assembly 46 (Figs. 7-8). One rotation of the piston cam 36 depresses the piston 26 to provide a 2 cc displacement of grease. The piston 26 is reset by the spring 30 located at the end of the piston 26 inside the cylinder 28. As can be seen most clearly in Fig. 8, the position cam 38 is rotatably mounted on the same shaft 78 as the piston cam 36, shown in phantom. Thus, when the piston cam 38 is rotated by the gear reduction transmission assembly 46 (Figs. 7-8), the position cam 38 is also rotated. The position cam 38 is used with the microswitch 40 to provide position input to the PCB timer 42.
Flow of grease (or, alternatively, oil as will be discussed later) is shown in Fig. 6. The grease is discharged via displacement of the internal piston 26 utilizing the inlet check valve 32 and the outlet check valve 34 to provide one way flow. In particular, when the piston 26 is permitted to retract due to the position of the piston cam 38 and the force of the spring 30, a partial vacuum is created and due to the biasing means 58/piston 60 in the lubricant reservoir 24, a predetermined amount (e.g., V2 cc) of grease pushes the ball 90 of the inlet check valve 32 away from its seat 92 against the force of a valve spring 94. This predetermined amount of grease then
makes it way into the cylinder 28 in the direction of the arrows 96, at which time the inlet check valve closes 32 (i.e., the ball 90 is returned to its seat 92). When the piston cam 36 drives the piston 26 (as will be discussed below) against the force of the spring 30, the predetermined amount of grease is pushed out of the cylinder 28 and pushes the ball 98 of the outlet check valve 34 away from its seat 100 against the force of a valve spring 103, thereby dispensing the predetermined amount of grease, in the direction of the arrows 102, to the particular lube point(s). Thus, the inlet check valve 32 prevents any back flow of the entered grease into the reservoir 24 during piston 26 compression and the outlet check valve 34 prevents any back flow of the dispensed grease during piston 26 extension. It should be noted that both the inlet check valve 32 and the outlet check valve 34 are both shown closed in Fig. 6; however, one skilled in the art would understand their alternating operation.
Operation of the PDP 20 is set forth below in accordance with Figs. 6-9. It is also assumed that the PDP 20 has already been primed, as will be discussed later. At the beginning of a lube cycle, the PCB timer 42 energizes the DC motor 44, causing the gear reduction transmission assembly 46 to rotate in the directions shown in Fig. 7; the gear reduction transmission assembly 46 reduces the 3000 rpm output of the D.C. motor 44 such that the shaft 78 causes the piston cam 36 (shown in phantom) to begin rotating at about 5 rpm, as well as the position cam 38, in the direction shown by the arrow 79.
As can be seen most clearly in Fig. 8, as the rotation of the shaft 78 continues, the tip 80 of the piston cam 36 sweeps against the piston 26 while a rider wheel 82 of the microswitch 40 rides along the periphery 83 of the position cam 38; when the rider wheel 82 rides along the periphery 83 of the position cam 38, the microswitch 40 is in an open condition. When the tip 80 arrives at the center point 84 of the piston 36, thereby defining the point at which the piston cam 36 has fully depressed the piston 26, the rider wheel 82 is just about to enter a depression 86 in the periphery of the position cam 38. As the shaft 78 continues to rotate, the rider wheel 82 enters the depression 86, thereby closing the microswitch 40; the microswitch 40 remains closed until the rider wheel 82 leaves the depression 86 and again returns to the periphery 83 of the position cam 38.
This closure of the microswitch 40 signals the PCB timer 42 to de-energize the motor 44 for 5 minutes. This results in the piston 36 being held in the fully depressed position, against the spring 30, for 5 minutes. This dwell time of 5 minutes helps to maintain the maximum pressure and ensure that the appropriate volume of lubricant is dispensed through the outlet check valve 34. After this time has expired, the motor 44 is again energized and the shaft 78 begins rotating again, with the tip 80 finishing its sweep across the piston 26 in the direction of the arrow 79 shown in Fig. 8. When the piston cam tip 80 is just about to disengage from the piston 26, and thereby returning to a reset position, the rider wheel 82 begins to ride out of the depression 86 and returns to the periphery 83, thereby opening the microswitch 40. This opening of the microswitch 40 signals the PCB timer 42 to de-energize the motor 44. At this point, the PDP 20 remains idle for the remainder of the selected lube cycle frequency time which is set by the end user via the DIP switch 70. Fig. 9 is a timing diagram of the microswitch 40 and the motor 44 operation.
The following defines the particular operation of the PDP 20 based on the DIP switch 70 settings; references to Switches 1-8 (SW#) and the ON/OFF condition are depicted in the timer electrical schematic of Fig. 10.
1. At Power on (SW1 to the ON position) the PCB timer 42 must operate the motor 44 until a microswitch 40 closure. Then the motor 44 is turned off.
2. The PCB timer 42 then waits 5 minutes, then runs the motor 44 until the microswitch 40 is opened. Once the microswitch 40 is opened, the PCB timer 42 shuts off the motor 44.
3. The motor 44 remains off until the "Off Time" (i.e., the remaining part of the lube cycle-see Fig. 9) is completed.
4. Once the "Off Time" is completed, the PCB timer 42 begins another lube cycle. As can be seen in Fig. 9, the lube cycle consists of operating the motor 44 until a microswitch 40 closure. The motor 44 is then turned off. The PCB timer 42 waits 5 minutes then turns the motor 44 on until the microswitch 44 opens. Once the microswitch 40 opens, the PCB timer 42 turns off the motor 44 and the motor 44 remains off until the "Off Time" is complete. Thus, the "Off Time" should work as a frequency setting. In addition, operation of the lube cycle should occur at the time
selected. For example, if SW7 is in the ON position, then the PDP 20 performs a lube cycle every 6 hours, not 6 hours, 5 minutes.
5. The switch settings must be cumulative (i.e., add to create a total time), for example: if SW7 (6 hours) and SW3 (18 hours) are both in the ON position, then the "Off Time" selected is 24 hours.
6. Priming: When SW2 is in the ON position, the motor 44 must run continuously. When SW2 is moved to the OFF position, the motor 44 stops. Next, SW1 should be moved to the OFF position and then moved back to the ON position. Proper operation of this sequence is important because it insures that the piston 26 of the PDP 20 is in the correct position to begin a lube cycle when the "Off Time" is completed.
As set forth below in Table 1 , depending on what lube cycle frequency is selected, the need to replace the reservoir 24 is also provided.
It should be understood that before a lube cycle is established by the end user, it is necessary to prime the PDP 20. In particular, the end user turns SW1 ON; next, SW2 is turned ON and the PDP 20 begins a continuous run. Once grease 56 is emitted from the outlet port 65, the end user turns SW2 OFF and then can select the appropriate switches SW3-8 for the desired lube cycle.
Table 1 : DIP Switch Settings
Lube Cycle Reservoir Frequency Replacement
Switch (SW#) "Off Time" Period
As shown in Fig. 10, the PCB timer 42 comprises the 8-position DIP switch 70, surface mount type, and a single sided circuit board 88 containing the necessary timing circuitry with all components being surface mount types; thus, the PCB timer 42 resides on the circuit board 88. As can be seen in Fig. 10, power to the D.C. motor 44 is controlled through the PCB timer 44 by turning ON/OFF the transistor Q1. The D.C. motor 44, the power pack 48 and the microswitch 40 are electrically coupled to the printed circuit board 88 (e.g., via pads 89, only three of which are depicted in Fig. 5). The PCB timer 44 has a 0 to 70 °C operating temperature and 95% relative humidity without condensation operation.
Alternatively, when oil is the lubricant being dispensed, a transparent, disposable canister 104 (LUBESITE model G-5) containing an end-user provided oil (e.g., 150-8000 ssu viscosity) is used. As shown in Fig. 4, the oil reservoir 104 comprises a spring-loaded lid 106 for permitting an oil source (not shown) to fill the reservoir 104. The oil reservoir 104 also comprises a threaded portion 108 for coupling to the threaded inlet port 64 of the pump assembly 22.
Operation of the PDP 20 using the oil reservoir 104 coupled thereto is similar to the operation of the PDP 20 previously described when the grease reservoir 24 is used. However, it should be noted that when the oil reservoir 104 is used, the flow control fittings that are coupled to the outlet port 65 are Bijur meter units (e.g., Bijur FJB meter units, rather than the Bijur control units 54A-54C discussed above) for proportioning the proper amount of oil to the various lube points. A more detailed discussion of both types of flow control fittings are discussed in a Bijur publication, "The Characteristics and Application of Single Line Resistance Type Systems" which is incorporated by reference herein.
The PDP 20, as described above, provides for the generation of a maximum output pressure of approximately 400 psi at the outlet port 65.
The following table is a summary of exemplary components of the PDP 20 and are not limited to those listed.
Table 2
It should be understood that the piston cam 36, the position cam 38, the microswitch 40, the PCB timer 42, the D.C. motor 44 and the gear reduction transmission assembly 46 form a positive control means for the flow rate of lubricant dispensing, i.e., there is a positive control of the lubricant being dispensed. This is in contradistinction to the devices disclosed in U.S. Patent No. 5,509,501 (Damme) where dispensing of the lubricant is determined by the characteristics of the spring that drives its associated piston.
Without further elaboration, the foregoing will so fully illustrate my invention that others may, by applying current or future knowledge, readily adopt the same for use under various conditions of service.