High efficiency, high pressure pump suitable for remote installations and solar power sources

Abstract

A pump head has a motor coupler; a motor mount; at least one piston housing; a fluid input; a fluid output; and a reciprocating piston to pump a fluid from fluid input to fluid output. The manifold has fluid input and output bores extending parallel with the reciprocating piston, and from end to end thereof. The motor mount has a mounting flange configured to couple to a motor, and a torsion sleeve extending from the flange. A torsion bolt is coupled with the piston housing. An elastomeric sleeve isolates the torsion bolt from torsion sleeve. The torsion bolt longitudinally compresses and radially expands the elastomeric sleeve toward and against the torsion sleeve. The reciprocating piston, piston housing, a first seal, and a second seal in combination define a fluid collection chamber for fluid that leaks past the first seal. A fluid conduit connects the fluid collection chamber to the fluid input. An over-pressure release valve assembly is coupled on an input with the fluid output from the pump head, and is configured to stay closed until a predetermined maximum pressure is exceeded, and when opened will spill fluid back to at least one of the fluid inlet or a fluid reservoir.

Claims

1. A pump head, comprising: a motor coupler having a coupling body and a motor connection sleeve, said motor connection sleeve configured to detachably couple with a rotary motor shaft, said rotary motor shaft defining a motor shaft rotary axis; a motor mount; at least one piston housing; a fluid input; a fluid output; and a reciprocating piston within said piston housing and in a fluid flow path between said fluid input and said fluid output configured to pump a fluid from said fluid input to said fluid output; said motor mount having a first mounting flange which is configured to couple said pump head to a motor; said first mounting flange having a motor mounting bolt having a longitudinal axis parallel to said motor shaft rotary axis and perpendicular to an axis along which said reciprocating piston reciprocates, said motor mounting bolt passing through said first mounting flange and configured to securely affix to said motor, a first coupling to which a torsion bolt is engaged, a torsion sleeve coupled with and extending from said first coupling on a first end of said torsion sleeve, said torsion sleeve extending longitudinally along an axis perpendicular to said motor mounting bolt and radially out from said motor connection sleeve, and an elastomeric sleeve internal to and longitudinally co-extensive with said torsion sleeve, said torsion bolt having an enlarged head end engaged with said elastomeric sleeve, a shaft extending from within said torsion sleeve, and a threaded end distal to said enlarged head end secured with and extending from said coupling body, said torsion bolt configured to longitudinally compress and thereby urge a radial expansion of said elastomeric sleeve when said torsion bolt is driven into said coupling body to thereby firm a connection between said first mounting flange and said coupling body, said elastomeric sleeve isolating said torsion bolt from said torsion sleeve.

2. The pump head of claim 1, wherein said motor mount further comprises: a second motor mounting bolt having a longitudinal axis parallel to said motor shaft rotary axis and perpendicular to said axis along which said reciprocating piston reciprocates, said second motor mounting bolt passing through said first mounting flange at a location on said first mounting flange more distal from said first motor mounting bolt than said first coupling and configured to couple said first mounting flange to said motor.

3. The pump head of claim 1, wherein said motor mount further comprises: a second mounting flange having a second mounting flange motor mounting bolt having a longitudinal axis parallel to said motor shaft rotary axis and perpendicular to said axis along which said reciprocating piston reciprocates, said second mounting flange motor mounting bolt passing through said second mounting flange and configured to securely affix to said motor, a second coupling to which a second torsion bolt is engaged; a second torsion sleeve coupled with and extending from said second coupling on a first end of said second torsion sleeve, said second torsion sleeve extending longitudinally along an axis perpendicular to said second mounting flange motor mounting bolt, radially out from said motor connection sleeve, and angularly offset from said first torsion sleeve, a second elastomeric sleeve internal to and longitudinally co-extensive with said second torsion sleeve, and said second torsion bolt having an enlarged head end engaged with said second elastomeric sleeve, a shaft extending from within said second torsion sleeve, and a threaded end distal to said enlarged head end secured with and extending from said coupling body, said second torsion bolt configured to longitudinally compress and thereby urge a radial expansion of said second elastomeric sleeve when said second torsion bolt is driven into said coupling body to thereby firm a connection between said second mounting flange and said coupling body, said second elastomeric sleeve isolating said second torsion bolt from said second torsion sleeve.

4. The pump head of claim 1, further comprising a cap enclosing said torsion sleeve, and thereby configured to operatively prevent access to said torsion bolt.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The foregoing and other objects, advantages, and novel features of the present invention can be understood and appreciated by reference to the following detailed description of the invention, taken in conjunction with the accompanying drawings, in which:

(2) FIG. 1 illustrates a preferred embodiment pump head designed in accord with the teachings of the present invention from a front isometric view.

(3) FIG. 2 illustrates the preferred embodiment pump head of FIG. 1 from a rear isometric view.

(4) FIG. 3 illustrates the preferred embodiment pump head of FIG. 1 from a top view.

(5) FIG. 4 illustrates the preferred embodiment pump head of FIG. 1 from a vertical plane sectional view taken along section line 4 of FIG. 3.

(6) FIG. 5 illustrates the preferred embodiment pump head of FIG. 1 from a vertical plane sectional view taken along section line 5 of FIG. 3.

(7) FIG. 6 illustrates the preferred embodiment pump head of FIG. 1 from a front view.

(8) FIG. 7 illustrates the preferred embodiment pump head of FIG. 1 from a vertical plane sectional view taken along section line 7 of FIG. 6.

(9) FIG. 8 illustrates the preferred embodiment pump head of FIG. 1 from a right side view.

(10) FIG. 9 illustrates the preferred embodiment pump head of FIG. 1 from a horizontal plane sectional view taken along section line 9 of FIG. 8.

(11) FIG. 10 illustrates the preferred embodiment pump head of FIG. 1 in further combination with a prior art motor from a front isometric view.

DESCRIPTION OF THE PREFERRED EMBODIMENT

(12) For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification.

(13) All numeric values are herein assumed to be modified by the term about, whether or not explicitly indicated. The term about generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (i.e., having the same function or result).

(14) The recitation of numerical ranges by endpoints includes all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

(15) Although some suitable dimensions ranges and/or values pertaining to various components, features and/or specifications are disclosed, one of skill in the art, incited by the present disclosure, would understand desired dimensions, ranges and/or values may deviate from those expressly disclosed.

(16) As used in this specification and the appended claims, the singular forms a, an, and the include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term or is generally employed in its sense including and/or unless the content clearly dictates otherwise.

(17) For the purposes of the present disclosure, a torque arm will be understood to be a member that prevents the pump head assembly from rotating relative to the motor frame, and instead insures that the all applied torque is applied to fluid pumping.

(18) The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The detailed description and the drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention. The illustrative embodiments depicted are intended only as exemplary. Selected features of any illustrative embodiment may be incorporated into an additional embodiment unless clearly stated to the contrary.

(19) FIGS. 1-3 illustrate pump head 100 in an assembled state. Pump head 100 has a motor coupler 110, motor mount 120, right piston housing 140, left piston housing 141, manifold 160, output 180, and overflow 190.

(20) Motor coupler 110 is configured to couple through coupling body 111 directly with a standard motor shaft, to transmit rotary power from the motor shaft into pump head 100. Motor connection sleeve 113 accomplishes this coupling, which as illustrated is a slotted sleeve that may receive a keyed shaft and associated key therein. Nevertheless, the type of motor connection is not critical to the present invention, and so other known motor couplers will be considered to be incorporated herein. Bearings 114 allow motor connection sleeve 113 to rotate freely within coupling body 111. At the end of motor connection sleeve 113 distal to the motor is a cam coupler 117 that allows motor connection sleeve 113 to engage with and directly drive cam 118. Cam coupler 117 is not centered on the central axis of cam 118. Therefore, as the motor shaft and motor connection sleeve 113 rotate cam 118, the outer periphery of cam 118 does not remain stationary.

(21) Cam 118 is engaged with piston 144 at saddle 145 as illustrated in FIG. 9. Consequently, when cam 118 is rotated by motor connection sleeve 113, it will function as an eccentric that in turn will drive piston 144 in a reciprocating motion, in one extreme position locating piston 144 farther into right piston housing 140 and farther out of left piston housing 141, and in the second extreme position locating piston 144 farther out of right piston housing 140 and farther into left piston housing 141. As piston 144 reciprocates in a horizontal plane, it is prevented from moving vertically up and down by cylinder 143. Nevertheless, cam 118 will of course not only drive left and right, but up and down as well. To permit this movement, while not incurring any consequential energy loss, cam drive bearing 119 encircles cam 118 and has an outside diameter slightly less than the width of saddle 145. Cam drive bearing 119 is thus configured to press against a first side of saddle 145 and climb with respect thereto on a first half rotation, while not contacting the opposite side of saddle 145 during this first half rotation. Bearing 119 will then press against the opposite side of saddle 145 and move downward with respect thereto on a second half rotation, while not contacting the first side of saddle 145.

(22) As described and illustrated, since cam 118 and cam drive bearing 119 are disposed in saddle 145 of piston 144, rotation of cam 118 results in reciprocating motion of piston 144. Thus, one revolution of motor connection sleeve 113 rotates cam 118 one revolution, which in turn results in one stroke of piston 144. A stroke of piston 144 is defined as a single back-and-forth cycle of the piston in which piston 144 travels from its furthest extent in a first direction (e.g., toward left piston housing 141) to its furthest extent in the opposite direction (e.g., toward right piston housing 140) and back to its furthest extent in the first direction.

(23) The volume of fluid output by pump head 100 during one stroke of piston 144 is considered the displacement of pump head 100. The displacement of pump head 100 is a function of the diameter of piston 144 and the stroke length (e.g., longitudinal movement) of piston 144. Thus, in some embodiments the displacement of pump head 100 may be changed by changing the diameter of piston 144 and/or the stroke length of piston 144. In some embodiments, a sleeve may be placed in the piston bore defined by cylinder 143 to accommodate a piston having a smaller diameter. Additionally and/or alternatively, in some embodiments cam 118 may be substituted with another cam having a different eccentricity, such as the opening of the cam being located at a different radial position from the center axis of the cam.

(24) When pump head 100 is operating, rotary motion from the rotary motor shaft is directly coupled to motor connection sleeve 113. Since cam 118 is affixed to motor connection sleeve 113, this rotation also moves cam 118. Owing to the eccentricity of cam 118, movement generates a cantilevered force against motor connection sleeve 113. This force is counteracted by both of the bearings 114, while the rollers within bearings 114 act as anti-friction devices. The direction of the force upon bearings 114 is one for which most bearings are designed to exhibit great strength and minimal wear, meaning that such force does not consequentially diminish the life of properly selected bearings.

(25) Bearing 119 encircles cam 118. During rotation of motor connection sleeve 113, bearing 119 is driven against saddle 145 of piston 144 by cam 118. Cam 118 is therefore also protected from any frictional energy loss and associated component wear by cam drive bearing 119, while still controlling the extent of eccentric movement. Once again, the force upon bearing 119 is in the proper direction for great strength and minimal wear.

(26) In view of the fixed couplings between drive chain members, with the only exceptions being bearings with properly oriented forces, there are no weak links in the preferred embodiment drive chain from motor shaft to piston 144. As long as the three bearings 114 and 119 are properly selected to withstand the radial loading described immediately herein above, and to have long life, then pump head 100 will be both extremely efficient, and also quite capable of generating extremely high pressures while still operating for a very extended time period (long MTBF).

(27) Many prior art reciprocating pumps require the use of a return spring to return the piston. However, in the preferred embodiment, the use of cam 118 in combination with cam drive bearing 119 and saddle 145 in piston 144 eliminates the need for a piston return spring. This not only reduces the parts count, it also further improves efficiency and MTBF.

(28) In addition to the drawbacks associated with efficiency and MTBF, a return spring may not always properly return. For exemplary purposes, a highly viscous liquid may delay and ultimately prevent the spring from fully returning the piston. This will alter the amount of fluid actually pumped during a single stroke. In contrast, cam 118 will positively drive piston 144 through the full stroke with each revolution, ensuring that the correct amount of fluid is actually pumped in any given stroke.

(29) In the most demanding applications, such as, for exemplary and non-limiting purposes, pipeline chemical injection pumps, both efficiency and MTBF are particularly critical, and even small improvements can translate into substantial cost savings over the life of the pump head. This is in part due to the very nature of the remote installation, making the cost to access and repair or replace a pump very high. Ideally, a preferred embodiment pump head 100 would be permanent for the life of the pipe line, thereby substantially lowering the annual and lifetime cost to operate the preferred embodiment pump head 100.

(30) Piston 144 with saddle 145 as disclosed herein is functionally identical to and structurally very similar to piston 44 illustrated and described in U.S. Pat. No. 9,316,216 by Cook et al, owned by the present assignee, and incorporated by reference herein above. Therefore, further illustration and understanding of the operation of this cam, saddle and piston may be gleaned therefrom.

(31) Motor mount 120 replaces and improves upon traditional hat-brim style pump head mounting flanges. These traditional mounting flanges have holes drilled at intervals around the brim region, and through the holes are affixed bolts to secure the pump head to a collar about the motor. Unfortunately, such prior art flanges do not accommodate any dimensional deviations that might, for exemplary purpose, lead to axial mis-alignment between motor connection sleeve 113 and the motor shaft. Furthermore, the prior art rigid coupling also necessitates higher starting torque, greater pulsation of drive, pump, and pumped fluid, and increased vibration transmission between motor and pump head. Higher starting torque is disadvantageous for starting amperage, making the prior art less conducive for use in non-grid applications such as solar powered pumping stations. The high starting torque of the prior art also increases peak forces on the moving components, which accelerates wear and decreases MTBF.

(32) In distinct contrast to the prior art brim, the present invention provides a motor mount 120 having a left mounting flange 121 and right mounting flange 122. The particular number of mounting flanges is not critical to the present invention, though at least two are preferred to better accommodate dimensional tolerances or other mismatches that may arise. Motor mounting bolts 123 are used to rigidly and securely fasten motor mount 120 to a motor, and lock washers 124 or any other method of securing fasteners may be provided to ensure that motor mounting bolts 123 do not unintentionally loosen over time.

(33) In the rare event that field service is required, and particularly in remote arctic locations, the service person may be working in extreme sub-zero conditions. In some prior art designs, this will require the service person to handle and precisely place small parts. This may be easily accomplished in the controlled environment of an office building or factory, but in extreme sub-zero conditions even the most manually dextrous persons will find the chore impossible. Most commonly in such a hostile environment, the service person will be wearing thick mittens to protect hands, and small parts simply cannot be manipulated.

(34) In contrast, the preferred embodiment is designed so that pump head 100 may be removed as a single unit and replaced with another like pump head. This will only require the removal of the motor mounting bolts 123 and input and output fluid couplers that connect to input connector 162 and output 180 respectively, followed by sliding of motor connection sleeve 113 from the motor shaft, and then installation of the replacement pump head including sliding of motor connection sleeve 113 onto the motor shaft, and subsequent replacement or reinstallation of the removed motor mounting bolts and fluid couplers. This can all be done easily by a service person wearing mittens and outfitted with an allen wrench or the like. While this may seem at first blush to be minor, again, in extreme sub-zero conditions, preferred motor mount 120 can be critical.

(35) Torsion sleeve 125 provides an outer rigid sleeve through which torsion bolt 127 will pass. Separating the two is a rubber or otherwise elastomeric torsion sleeve 128 which is configured to reduce vibration from passing through, and allowing peak impulses of torsional energy to be stored and later released. As may best be appreciated from FIG. 9, the head of torsion bolt 127 extends at least across a shoulder within elastomeric torsion sleeve 128. In a contemplated alternative embodiment, the head of torsion bolt 127 may extend partially, but not completely, across the end of elastomeric torsion sleeve 128. In either case, when torsion bolt 127 is tightened into coupling body 111, this will cause elastomeric torsion sleeve 128 to compress longitudinally, and in turn expand radially. As may be appreciated then, prior to compression, elastomeric torsion sleeve 128 may fit easily within torsion sleeve 125. However, when compressed by torsion bolt 127, elastomeric torsion sleeve 128 will radially expand and compress against torsion sleeve 125, thereby firming the connection between the associated mounting flange 121, 122 and coupling body 111.

(36) While a sleeve geometry is described and illustrated for elastomeric torsion sleeve 128, it will be appreciated that other geometries that accomplish the intended isolation between torsion sleeve 125 and torsion bolt 127 are also contemplated herein. The elastomeric isolation means that peak rotational forces are dampened, while torsion sleeve 125 still functions as a torsion arm. Reducing peak rotational forces not only helps to increase Mean Time Between Failure (MTBF), it also reduces peak current draw of the motor, making the motor more suitable to use in solar powered and other applications sensitive to peak current draw. This also helps to reduce pulsation within the pumped fluid, by smoothing out the piston drive force. In the event of catastrophic failure of rubber torsion sleeve 128, which is highly unlikely due to the fact that forces applied thereto are entirely compressive in nature, torsion bolt 127 will still be constrained by and within torsion sleeve 125. This constrainment helps to ensure that pump head 100 will not be consequentially harmed or destroyed, even if rubber torsion sleeve 128 catastrophically fails.

(37) An optional cap 126 may be provided to enclose torsion bolt 127, thereby reducing the chance that a service person would mistakenly remove torsion bolts 127 rather than removing motor mounting bolts 123, in the rare event that service is required. Once again, this may at first blush appear to be minor, but in extreme sub-zero conditions, this can be critical.

(38) FIGS. 4-9 illustrate the internal fluid passages and piston operation in greater detail. Right piston housing 140 and left piston housing 141 each provide a central bore that defines cylinder 143 through which piston 144 travels in reciprocating motion. Manifold anchor bolts 142 are provided to secure manifold 160 to each of the piston housings 140, 141. As already described herein above with reference to FIG. 9, a recess or saddle 145 in piston 144 serves to engage with cam drive bearing 119 and transmit rotary motion from a motor shaft through to piston 144. Continuing with FIG. 9, when piston 144 reciprocates within cylinder 143, at each end thereof piston housings 140, 141 define chambers that are alternately being compressed and being vacuumed. To maintain this alternating compression and vacuum, a pair of high pressure piston outer seals 146, also visible in FIG. 9, are provided.

(39) When these high pressure piston outer seals 146 are functioning perfectly, there will be no leakage of the pumped fluid past. However, over time even tiny amounts of leakage may tend to accumulate. Further, and with proper design and construction only with very great aging of components, piston outer seals 146 may begin to or completely fail. In such instances, it is desirable to avoid any accumulation of fluids.

(40) A pair of piston inner seals 147 are provided that together with high pressure piston outer seals 146 define a chamber that collects any fluid bypassing high pressure piston outer seals 146. This fluid is then conducted through piston bypass drain bore 148, visible in FIG. 9, to bypass passages 152, 153. Turning now to FIG. 5, one of bypass passages 152, 153 connects with bypass bore 154 in manifold 160, which in turn ultimately connects with input bore 163 and from there to the input supply line and fluid source reservoir. As visible in FIG. 5, bypass passage 152 within right piston housing 140 connects to bypass bore 154, and bypass passage 153 terminates at the face of manifold 160. Noteworthy here is that right and left piston housings 140, 141 are fabricated with identical geometry, and are simply rotated through a half-circle relative to each other at the time of installation. This means that while bypass passage 152 within right piston housing 140 connects to bypass bore 154, and bypass passage 153 terminates, in left piston housing 141 bypass passage 153 connects to bypass bore 154, and bypass passage 152 terminates.

(41) Turning to FIG. 4, input check valve assembly 150 couples piston 144 to input to piston housing bore 164, which in turn couples to input bore 163. Input check valve assembly 150 is a one-way check valve, assuring that during movement of piston 144 in a first direction (away as viewed in FIG. 4), fluid is drawn into cylinder 143. However, when piston 144 changes direction and moves towards the reader in FIG. 4, input check valve assembly 150 will close preventing fluid from undesirably being pumped back into the inlet bore 163. Instead, output check valve assembly 151 will now open, allowing fluid within cylinder 143 to be pumped through output check valve assembly 151 and onward through the output to piston housing bore 166 and then to output bore 165. The combination of piston 144 with good high pressure piston outer and inner seals 146, 147, along with good high pressure input and output check valve assemblies 150, 151 ensures generation of adequate vacuum on the inlet side to be both self priming for nearly all materials, and to be compatible through a wide range of viscosities as well. This in turn helps to ensure that the preferred embodiment will not require human intervention to start fluid flow, even through very diverse ambient temperatures, and with a very wide range of fluid chemical compositions.

(42) Manifold 160 supports piston housings 140, 141, through manifold anchor bolts 142 that pass through the piston housings and secure into manifold 160. In turn, anchor bolts 161 couple manifold 160 and to motor coupler 110, and in the process sandwich piston housings 140, 141 between.

(43) Manifold 160 is provided with an input connector 162, which as illustrated comprises a female threaded connector. Nevertheless, any suitable fluid connector may be used, and the female threaded connector is purely exemplary. Input connector 162 is in fluid communication with input bore 163, thereby ensuring that fluid arriving from a fluid reservoir through input connector 162 will be passed through to input bore 163, then to the input to piston housing bore 164, and then alternately into distal ends of cylinder 143.

(44) A plurality of caps 167 may be used to terminate the main bores in manifold 160, which are the input bore 163 and output bore 165, leaving only a single input connector 162 supplying fluid into pump head 100. As long as input bore 163 runs essentially the entire length of manifold 160, then input supply fluid will be delivered to both right piston housing 140 and left piston housing 141, adjacent to opposed ends of piston 144. This allows pump head 100 to operate as a double acting simplex positive displacement pump, which means that pump head 100 will be pumping in both directions of piston movement, for the entire motor shaft rotation. Some examples of double acting simplex positive displacement plunger pumps are described in U.S. Pat. Nos. 4,978,284, 5,173,039, 5,183,396, 6,257,843 and 6,527,524 owned by the present assignee, the disclosures of which are incorporated herein by reference.

(45) Fittings, such as hose fittings, may be coupled to the inlet and outlet bores of the manifold as desired to couple fluid inlet and fluid outlet lines (e.g., hoses, pipes, etc.) to pump head 100. Such fittings may include elbows, tees, reducers, couplers, caps, ball valves, stopcock valves, or any other suitable or desirable coupling. Further, various instrumentation or other apparatus may also optionally be coupled into pump head 100 either through input connector 162 and output 180, or at any other suitable location or access point. As but one non-limiting but illustrative example, one or more of caps 167 may be removed to affix instrumentation such as pressure gauges or any other suitable or desired instrumentation.

(46) As illustrated in FIG. 7, output bore 165 which runs transverse to the motor shaft longitudinal axis is in free fluid communication with output axial bore 168, which runs parallel to the motor shaft longitudinal axis. Fluid traveling out of pump head 100 through output 180 will first pass through back flow valve 182, which as the name suggests will simply ensure that fluid only passes out of pump head 100 at output 180, and not back in. An o-ring seal 184 or the like may be provided to provide a leak-free seal between the output nipple and manifold 160.

(47) While for normal operation, the aforementioned output is adequate, there may be unforeseeable circumstances where a blockage develops in plumbing external to pump head 100, such as for exemplary purposes a natural gas pipeline, or where blockage develops in the plumbing coupling piston 144 to the external plumbing, such as through failure of back flow valve 182 to open. In such cases, the continued reciprocation of piston 144 will quickly increase pressure from piston 144 through the output bore 165 and to the point of blockage to dangerous levels that can lead to ruptures in the plumbing, or permanent damage to pump head 100 or to a motor such as motor 10 illustrate in FIG. 10. To prevent or greatly reduce the likelihood of such damage, an output to over-pressure bore 169 couples output axial bore 168 to over-pressure release valve assembly 170. Over-pressure valve assembly 170 is configured to stay closed until a predetermined maximum pressure is exceeded. For exemplary purposes, this pressure threshold may be selected to ensure that at no time will the pump head exceed a maximum safe pressure. Over-pressure valve assembly 170 comprises an over-pressure release ball 171, over-pressure release spring 172, and over-pressure release end stop 173. When the pressure threshold of over-pressure valve assembly 170 is exceeded, then over-pressure release ball 171 will be pushed with sufficient force to overcome the opposing force provided by over-pressure release spring 172, and thereby unseat over-pressure release ball 171. This permits pressurized fluid within output axial bore 168 to pass through over-pressure valve assembly 170 and within internal bore 175, thereby lowering the pressure within axial bore 168 to an acceptable level. An over-pressure release end stop 173 is provided that maintains the compression of over-pressure release spring 172. In a preferred embodiment, over-pressure release end stop 173 is at a fixed distance from over-pressure release ball 171, and therefore sets a fixed activation pressure for opening over-pressure valve assembly 170. Nevertheless, in an alternative embodiment contemplated herein, over-pressure release end stop 173 may be adjustable to be either closer to or farther from over-pressure release ball 171, in which case the activation pressure for opening over-pressure valve assembly 170 may thereby also be adjustable.

(48) An o-ring seal 174 may be provided to seal an overflow output nipple 190 to manifold 160. Most preferably, overflow output nipple 190 will be in fluid communication with at least one of the fluid reservoir, fluid input line, input connector 162, or input bore 163. This may, for exemplary and non-limiting purpose, be achieved through external tubes and fittings that affix to overflow output nipple 190. As may be apparent then, if there is a blockage preventing fluid from being pumped through output 180, piston 144 will simply draw fluid from the fluid reservoir, and return the fluid back to the reservoir via overflow output nipple 190.

(49) FIG. 10 illustrates preferred embodiment pump head 100 in further combination with a prior art motor 10. While an electric motor is illustrated and preferred, the present invention is not solely limited thereto, and other types of motors may be used in alternative embodiments.

(50) Motor 10 may, for exemplary and non-limiting purposes, be provided with some type of motor mounting bracket, such as motor mounting bracket 12 illustrated. Pump head 100 is securely affixed to motor 10 by sliding motor connection sleeve 113 onto the motor shaft (not visible), and then affixing motor mounting bolts 123 into motor 10, for exemplary purposes such as at threaded mounting holes provided in the motor collar. As may be apparent, the exact number, spacing, size, and coupler type of motor mounting bolts 123 will vary depending upon the type of coupler provided with motor 10.

(51) As visible in FIG. 9, motor connection sleeve 113 may optionally have one or more threaded holes formed therein to accommodate a set screw. If this set screw hole is aligned with access hole 112 visible for example in FIG. 7, or a similar optional access hole such as illustrated in FIG. 9, then an installer may also secure motor connection sleeve 113 to the motor shaft using such as set screw.

(52) In an alternative embodiment contemplated herein, a clutch or transmission maybe connected between electric motor 10 and motor connection sleeve 113 to control or alter the transmission of power from electric motor 10 into pump head 100. As used herein, a transmission will be understood to be an assembly of associated parts by which rotational power is converted from a first rotational speed or rate at the power input of the transmission to a second possibly different rotational speed or rate at the power output of the transmission. As used herein the terms speed or rate may refer to a fixed speed or rate or a variable speed or rate unless the content clearly dictates otherwise.

(53) In some embodiments, the transmission may include one or more chains and sprockets, one or more belts and pulleys, one or more gears, etc. used to alter the output speed from the input speed. In some embodiments, the transmission may be a speed reduction, such as a gear reduction including one or more gears reducing the rotational rate of the output shaft from the rotational rate of the input shaft, while in other embodiments the transmission may be a speed accelerator, such as a gear accelerator including one or more gears increasing the rotational rate of the output shaft from the rotational rate of the input shaft.

(54) In addition to the provision of a transmission, or alternatively thereto, in some embodiments of the invention, motor 10 may be configured to run at more than one speed. The speed may for exemplary purpose be varied by a speed controller or switch.

(55) Pump head 100 may be manufactured from a variety of materials, including metals, resins and plastics, ceramics, or even combinations or composites of the above. The specific material used may vary, though special benefits are attainable if several important factors are taken into consideration. First, anticipated chemical exposure associated with a particular application may dictate material choice. There are many chemicals that are corrosive to ordinary carbon steel, and in such instances, various ceramics and stainless steel compositions are preferred. Additionally, there are a variety of polymers that are also relatively chemically inert. However, few polymers have the combination of strength and temperature resistance that most of the components of the present invention demand for most applications. One notable exception is the material used for the various seals described herein above, where there are several known polymers and natural and synthetic rubber compositions that might be selected, again depending upon the specific requirements of an application. In addition to chemical resistance, temperature resistance, strength, abrasion resistance, and other known factors will be considered. As may be apparent then, it is preferable that all materials are sufficiently tough and durable to not fracture, even when great forces are applied thereto. In the case of preferred embodiment pup head 100, a preferred material for the majority of components is stainless steel, which offers great strength and excellent corrosion resistance against a wide variety of chemicals. While stainless steel might be suitable for some applications as the material used to fabricate piston 144, various ceramics known in the pump industry may be preferable. Consequently, for application to extreme conditions and a wide range of chemical compositions, particularly such as may be encountered in the demanding application of chemical injection pump connected to a natural gas pipeline, a combination of ceramic piston, chemically inert polymer seals, and the vast majority of remaining components fabricated from stainless steel is preferable. Nevertheless, those skilled in the art will readily understand the requirements in light of the present disclosure for a given application, and so will be able to select a suitable set of compositions.

(56) While the foregoing details what is felt to be the preferred embodiment of the invention and many alternatives thereto, no material limitations to the scope of the claimed invention are intended. Further, features and design alternatives that would be obvious to one of ordinary skill in the art are considered to be incorporated herein. The scope of the invention is set forth and particularly described in the claims herein below.