US3232234A - Pump with bypass - Google Patents

Description

Feb. 1, 1966 A. J. BUTTERWQRTH 3,232,234 I PUMP WITH BYPASS Filed May 23, 1962 7 Sheets-Sheet 1 ARCH/BALD dame-s fiurrfkwolem 2 1966 A. J. BUTTERWORTH I 3,232,234

PUMP WITH BYPASS 7 Sheets-Sheet 2 Filed May 23, 1962 Amen/rm Feb. 1, 1966 Filed May 23, 1962 A. J. BUTTERWORTH PUMP WITH BYPASS 7 Sheets-Sheet 5 1966 A. J. BUTTERWQRTH 3,232,234

PUMP WITH BYPASS Flled May 23, 1962 7 Sheets-Sheet 4.

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PUMP WITH BYPASS '7 Sheets-Sheet 5 Filed May 25, 1962 m ww Q Q Feb. 1, 1966 A. J. BUTTEVRWORTH 3,232,234

PUMP WITH BYPASS Filed May 23, 1962 '7 Sheets-Sheet 6 bvwwraa deem/3.4m Jam: fiurrmwmrx/ Feb. 1, 1966 A. J". BUTTERWORTH 3,232,234

PUMP WITH BYPASS '7 Sheets-Sheet '7 Filed May 23, 1962 bwewmx United States Patent 3,232,234 PUMP WITH BYPASS Archibald James Butterworth, Frimley, England, assignor to Butterworth Engineering Co. Limited, Frimley, England, a British company Filed May 23, 1962, Ser. No. 196,974 Claims priority, application Great Britain, May 25, 1961, 18,853/61; Jan. 25, 1962, 2,767/62 9 Claims. (Cl. 103-41) This invention relates to pumps for intermittent duty and capable of being driven whilst inoperative.

It is common in the case of continuously rotating machinery, such as prime movers of various kinds, for there to be duties of an auxiliary nature, which can most conveniently be performed by a fluid pump driven from the main machine. A typical case might be the engine of an automobile, where occasional tasks such as the operation of raising and lowering the top of convertible coachwork, or operating jacking or parking equipment, might be carried out by hydraulic fluid under pressure from a pump driven by the engine, either by an independent belt drive or bolted to the rear of the engine dynamo and coupled to the armature thereof in a known manner.

When this equipment is not in use, such a pump might be mechanically disengaged, so that it was stationary; or it might be continuously running, and its output of fluid, for example oil, might circulate continuously from the pump through a control valve and a reservoir, and thence back to the pump. It has proved difficult to design a cheap method of mechanically engaging and disengaging such a pump so most installations of this kind either use a continuous idle circulation of oil from a continuously running pump, as mentioned above, or a more expensive arrangement consisting of an electric motor coupled to a small hydraulic pump, the motor being energized from batteries when required.

There are several disadvantages to the continual circulation of oil through a series of hoses, control valve, reservoir, etc., particularly when the equipment is such that a substantial volume of oil needs to be displaced at low engine speeds, since the idling circulation at high engine speeds then tends to be excessive, resulting in aeration and overflow troubles, and requiring large diameter expensive hoses. An object of the present invention is to retain the mechanical simplicity of the continuously running pump without the need for any external idling circulation of oil.

In this invention the control means are incorporated with the pump, and in one form, when a control rod is pushed to the Off position, the mechanical arrangement of the pump components is changed so that there is no fluid pumping action, In another form of the invention, when the control rod is in the Off position, the pumping action continues, but the entire flow from the pumping elements is returned through a large passage inside the pump to the suction side, so that no significant pressure is developed, and there is no external circulation of oil. In either case the oil reservoir may be mounted either directly on top of the pump, or remotely therefrom; and provision may be made for a slow interchange of fluid between the reservoir and the pump passages, to pevent continuous agitation of one small part of the available oil. In most types of equipment to be operated by such a pump only one pipeline will be required, connecting the pump and the accessory equipment.

In such a pump it may be desirable for the equipment to fail safe, i.e. the pump may be required to revert to idle circulation with the control rod in the Off position whenever the engine is stopped, independently of whether the operator returns it to the Oli" position ianually.

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According to this invention a pump for intermittent duty and capable of being driven whilst in operation comprises two spaces within the pump body one communicating with the suction side of the pump and with an inlet port and the other communicating with the pressure side of the pump and an outlet port and valve means within the pump body arranged at opposite limits of movement thereof to cut off and establish communication between said two spaces whereby the pump may be rendered operative and inoperative respectively whilst being driven.

Means may be provided for moving a part of said valve means to a position at one limit of its movement where it cuts off communication between said two spaces and wherein yieldable detent means are provided for holding said valve means at said one limiting position.

Spring means may be provided for yieldingly resisting the movement of said part of the valve means to said one limiting position for cutting ofi communication between said two spaces and wherein the yieldable detent means comprise two oppositely directed faces of diiferent effective areas on said part of the valve means which faces when said parts of the valve means is in the said one limiting position, are both subjected to the pressure in the space which communicates with the pressure side of the pump and are so disposed that the resultant force on them is in a direction to maintain said part of the valve means in said one limiting position against the action of the spring means so long as the pump develops a predetermined pressure, but should the pressure drop, said spring means return said part of the valve means to a position where it places said two spaces into communication with one another.

Independent hand control means may be provided for placing the two aforesaid spaces into communication with one another.

Means responsive to pressure on the pressure side of the pump may be arranged to establish communication between said two spaces at a predetermined pressure.

In the case where the pump is of the meshing gear wheel kind, said two spaces may be arranged on opposite sides of the zone of meshing and communication between them is controlled by a part of said valve means.

Said gear wheels may be mounted in circular intersecting recesses in the pump body which recesses are closed on one side by a fixed wall so that the two spaces on opposite sides of the meshing zone are isolated from one another on that side and wherein on the other side of the intersecting recesses is arranged a sealing member which is movable towards and away from the faces of the gear wheels in an axial direction so that in one limiting position it isolates said two spaces on opposite sides of the meshing zone and renders the pump effective whereas in the other limiting position of the sealing member said two spaces may communicate with one another and the pump is rendered ineffective, which sealing member constitutes the movable part of said valve means and a manipulating member for imparting movement to said sealing member.

There may be provided instead of said fixed wall a floating wall so shaped and dimensioned that when the pump is effective the resultant force from the fluid pressure on opposite faces of the wall is such that the wall is moved to a position adjacent the gear wheels so that the two spaces on opposite sides of the meshing zone are isolated from one another on that side.

A reservoir for operating fluid may be mounted directly on the pump body and communicates with said inlet port and low pressure space.

In the case where a passage leads from said inlet port to a fluid reservoir, a fluid diverter may be associated with said inlet port and is adapted, when said valve means is in a position to establish communication between the high and low pressure spaces, to direct a proportion of the flow of fiuid from the high pressure space to the low pressure space to flow back into said reservoir for the purpose described.

Other features of the invention are set out in the following description and claims.

The following is a description of several embodiments of the invention, reference being made to the accompanying drawings in which:

FIGURE 1 is an axial view of one embodiment sectioned in the plane of one of the jointing faces, i.e. sectioned on the line 1--1 of FIGURE 2;

FIGURE 2 is a section on the crooked line 2-2 of FIGURE 1;

IGURE 3 is a section on the line 3-3 of FIGURE 2;

FIGURE 4 is an external rear view of the pump from .the same aspect as FIGURE 1;

FIGURE 4A is a view of a part of FIGURE 2 on an enlarged scale;

FIGURE 5 is a section of a further embodiment on the crooked line 55 of FIGURE 12;

FIGURE 6 is a section on the line 66 of FIGURE 5;

FIGURE 7 is a section on the line 7-7 of FIGURE 5;

FIGURE 8 is a view of a part of FIGURE 5 on an enlarged scale;

FIGURE 9 is a similar view to FIGURE 8 but with the relief valve rod in a different position;

FIGURE 10 is a section on the line 10-10 of FIG- URE 6;

FIGURE 11 is a plot of relief valve movement and spring deflection against pump pressure; and

FIGURE 12 is an elevation from the right of FIGURE 5 with certain parts removed.

The pump shown in FIGURES 1 to 4 is of the conventional gear type, having gear wheels 1 rotating in a closely fitting casing or body 2, sandwiched between end components 3 and 4 of the casing which components carry the bearings wherein rotate the spindles 5 and 6 supporting the gear wheels 1. The spindle 6, which drives the right-hand gear wheel 1, as viewed in FIGURE 1, has a driving slot 7, formed on its left-hand end (as viewed in FIGURE 2) which slot is connected for example to a coupling driven by the dynamo armature of an engine (not shown). This spindle 6, and the gear wheel which may be keyed to it, rotate in an anticlockwise direction as viewed in FIGURE 1, and the spaces between its gear teeth carry oil upwards on the right of the wheel in the direction of the arrow 8. Similarly the gear wheel carried by spindle 5, and driven by the right-hand gear wheel, will carry oil upwards on the left-hand side of it in the direction of the arrow 9. Oil will be squeezed from the spaces between the teeth when they mesh in a downward direction and thus the oil in the space between the wheels on the upper side of where they mesh will be under pressure whereas the space on the underside of the locality of meshing will be under suction. A passage 10 in the right-hand end component 3 of the casing communicates with said lower space and serves as a suction passage for the pump, and can draw oil through a vertical port 11 thereof and through a tube 12 from a reservoir 13.

However, when a control rod and valve 14 is in the Off position, as shown in FIGURE 2, oil delivered to the space 15 by the action of the gear wheels is free to pass through a bore 16, and re-circulate through the passages 11 and 10 to the suction side of the pump. Owing to the form of the double-walled tube 17 shown in FIGURE 3, some of this oil flowing through the bores 16 to the passage 11 will be deflected upwards by virtue of its velocity, and will flow out through passages 18 and 19 into that part of the reservoir 13 lying above a filter 20. At the same time it will be replaced by oil descending down the tube 12, which oil is drawn through the filter 20, thus ensuring a gentle low speed circulation of oil through the pump.

The control rod 14 is formed with a groove 21 engaged by a plunger 22 of a solenoid 23, which can render the pump inoperable, for example at unsuitable speeds of the engine in a known manner. When this plunger 22 is withdrawn by energising the solenoid 23, and when the control rod 14 has been moved to the right by pulling on a control knob (not shown) connected by a suitable joint and rod to the right-hand end 24 of the control rod 14, a portion 25 of the control rod 14 which lies to the left of a reduced portion 26, will enter the bore 16, thus effectively blocking the free circulation of oil through the passages 11 and 10. Pressure will thus be generated and oil will be driven through an outlet 27 shown in FIGURE 4. This outlet connects with the space 15, and carries pipe threads by which it is connected to a suitable hose or pipe, and thence to the equipment which it is desired to operate, for example a hydraulic ram (not shown). When this ram has been fully extended, and if it is desired to maintain it under pressure for a period, excess oil may be returned to the suction side of the pump by entering a hole 28 in the control rod 14, and thence passing down an axial hole 29 and displacing a plunger 30 which forms part of a safety valve assembly. The plunger 30 is normally maintained in the position shown in FIGURE 2 by a spring 31 and a screwed abutment 32. When the plunger 30 has been driven to the left, oil escapes through a crosseddrilled-hole 33, which in the right-hand or On position of the control valve 14 will be in line with the passage 11. If the left-hand portion 25 of the control rod 14 is reduced in diameter relative to a central portion 34, this difference in diametcr will create a rightwards force on the rod 14 when acted upon by the hydraulic pressure sufiicient to maintain the control valve in the On position against the effort of a return spring 35.

This differential pressure, and the pressure of the return spring 35, may be so proportioned that when the pressure falls away inside the pump body, for example due to pressure leakage when the engine is switched off, the control valve will return to its leftward position. Similarly the control rod and valve may be pushed to the left-hand position by manual effort of the operator aiding the return spring 35 to overcome the differential pressure mentioned above.

If this self-cancelling effect is not required, portions 25 and 34 of the control rod 14 may be the same diameter, and the return spring 35 is not needed, the control rod being maintained in the On or Off position by a detent and grooves of a known type.

FIGURE 5 shows a further embodiment employing a gear type pump wherein a casing 101 encloses gear-wheels 102, and has a cover 103 so as to provide a space 102a above the gear wheels under pressure and a space 10212 below the wheels under reduced pressure. A space 104 is formed in the upper part of the casing 101, and has inserted in it a tubular connection 105 connected to a reservoir, not shown, by a dual-passage flexible tube 106. Alternatively, the reservoir may be mounted directly on the pump body 101, as shown in FIGURES l, 2 and 4.

The tubular connection 105 incorporates a smaller tubular component 107, whose lower part is folded so that it may conveniently be attached to the lower part of tube 105, as shown in FIGURE 7. The lower part of component 107, is so shaped that it can collect a proportion of the oil emerging from a passage 136, so as to set up a cooling circulation as described above and thus acting as a fluid diverter. A housing 109 is attached to the outer face of the cover 103 by means of screws 108 shown in FIGURE 6. The housing 109 is located centrally about a bore 110 in the cover 103 by means of a spigot 111, which may be a press fit in the housing 109, and an easier fit in the cover 103, or vice versa.

A control rod and compound plunger 112 slides in the bore 110 in the cover 103 and a reduced diameter portion 112a at the rear of the plunger slides in a bore 113 at the rear of the housing 109. The housing 109 also contains a return spring 114, and is machined at 115a to accept a reduced portion 11512 of a solenoid 115. The control rod 112 has formed upon it a groove 116, which may be engaged by a plunger 115a constituting a part of the armature of the solenoid 115 and in the position shown in FIGURE 5 locks the pump out of action by shorting its pressure and suction sides as described above. To the rear of the groove 116, against the shoulder formed by the reduced portion 112a of the control rod 112, is located an abutment washer 118, whose purpose is to limit the travel of the control rod 112 by coming in contact with an abutment 119 formed by a reduction in the diameter of a spring housing bore 120 of the housing 109.

The terms forward and rear when referring to the pumps shown in the drawings may be taken as lefthand and right-hand respectively. The flange 121 shown at the left-hand end of FIGURE 5 is adapted for attachment to the rear of a car generator.

The flange 121 has a plurality of holes 121a drilled and counter-bored in it to suit the four attachment screws 122, which fit into tapped holes in the pump mounting. The flange 121 can thus be secured to the pump mounting in a number of positions to suit the installation in a known manner. The control rod 112 has a bore 124 at its forward end, and a smaller diameter bore 125 through its central portion. It is also counter-bored at 130 from its rearward end to a point just short of the groove 116. These details are seen more clearly in FIGURES 8 and 9, which are enlarged views of the control valve and its associated components.

A relief valve rod and plunger 126 is formed with enlarged portions 127 and 128, the latter being engaged with the bore 124 in the control rod 112, so that its rear face normally abuts against the rear face of the bore 124. A reduced portion 129 of the rod 126 passes through the smaller bore 125, and extends through the greater part of the counter-bore 130 at the rear end of the control rod 112. A spring 131 encircles the reduced portion 129 of the rod 126 within the counter-bore and at one end abuts the shoulder 125a between the bore 125 on a counter-bore 130 and at the other end abuts a nut 132 which engages a short threaded portion of the extreme rear of the rod 126.

The rearward end of control rod 112 is closed and sealed by a plug 133 carrying an O-ring type seal 134. The plug 133 is retained by a pin or bolt, not shown, passing through cross-drilling 135, which also serves to attach the operating rod to control rod 112 through an interposed flexible joint, for example a Hookes joint, indicated diagrammatically at'139a.

The pump body 101 has formed in it coaxial With bore 110 in the cover 103 a bore 136 which is a close sliding fit about left-hand enlarged portion 127 of the relief valve rod 126. This bore 136 breaks into the space 104 which connects with a passage 137, communicating with the lower and suction side of the pump through adrilling 138.

When the engine is running normally, with the pump out of use, control rod 112 will be maintained at its forward or left hand extremity of movement by the spring 114.

Its movement in this direction may be limited by the forward face of a universal joint 139a (shown in chain line) abutting against the rear face of housing 109. In the absence of pressure in the system, relief valve rod 126 will be maintained in its rearward position in relation to control rod 112 by the action of spring 131, so that when the control rod 112 is moved by pulling on a control knob (not shown), and transmission through the universal joint, the rods 112 and 126 will move together as one piece. Control rod 112 may be locked in its forward position by the armature plunger 1150 associated with solenoid entering the groove 116 in the rod 112 but when this plunger is withdrawn, as described in the specification, the rods 112 and 126 may be moved in a rearward direction, that is to say to the right, until they occupy the position shown in FIGURE 8 when the enlarged portion 127 of the rod 126 will be fully entered in the bore 136.

As the pump gear-wheels 102 are being continuously driven by the engine and are causing oil to circulate continuously through the passages 136, 137 and 138, the closing of the bore 136 will result in an immediate pressure rise. The first effect of this pressure rise will be to retain the rods 112 and 126 in their rearward or right hand position, owing to the fact that the major diameter of the rod 112 is larger than the diameter of the portion 127 of the rod 126. As described above this difference in diameter will cause a rightward force suflicient to overcome the resistance of the spring 114. The only path of escape for the oil is now through passage 140 to outlet port 141, shown in FIGURE 10. Outlet port 141 is connected to the equipment to be operated by unions and piping (not shown). Pressure in the system will rise to the point necessary to operate the accessory equipment for example hydraulic rams and when these rams have been fully extended, and there is no capacity for further delivery of oil through the outlet port 141, there will be a further rise in pressure.

The diameter of the enlarged portion 128 is arranged to be somewhat smaller than that of portion 127, so that when pressure is applied to their inward faces (i.e. their faces exposed to the space 102a above the gear wheels) there will be a resulting axial force tending to move the rod 126 in the direction of the larger area, that is to say, in a forward or a leftward direction, as illustrated. The force of spring 131 is arranged to counteract this leftward force until a pressure slightly below the intended maximum is reached. At the normal working pressure, while the hydraulic rams of the equipment are being extended, the spring 131 will already have started to compress, and the rod 126 will have moved leftwards in the passage 136 towards the position shown in FIGURE 9. Owing to the length of the spring 131 and its consequent low rate, there will only be a small increase in spring force between the position of the rod 126, shown in FIGURE 8, and its extreme leftward position shown in FIGURE 9. Consequently, there will be a very fiat cutoff of pressure when this relief valve is working, even in the case where pump revolutions are raised to an excessive level by the driver accidentally speeding up his engine to an unnecessary degree. This is a valuable feature in a pump of this type, as otherwise dangerously high pressures might be attained, causing damage to the accessory equipment.

It will be seen from FIGURE 9 that as rod 126 moves leftward relative to control rod 112, an annular space 143 is created between the rear face of the bore 124 and the rear face of the enlarged portion 123 of the rod 126. A drilling 144 (FIGURE 8) extends from the leftward end of the rod 126 to a point near the rear of the portion 128, and communicates with this space 143 by a diagonal drilling 145. By means of these passages, oil or other hydraulic fluid is admitted to fill space 143, and some of this oil also passes down the clearance between the aforesaid small bore and reduced cylindrical portion 129 of the rod 126, to fill the space created by the withdrawal of part of the rod 129 from the counterbore 130. By suitable proportioning of the drillings 144 and 145, and the clearance around rod 129 and the major diameter of the shouldered nut 132, sufficient fluid resistance to these movements of oil may be created so as to apply any desired degree of damping to the movement of rod 126, which might otherwise tend to vibrate excessively owning to the effect of dynamically induced pressure differences .7 between the rear face of portion 127 and the front face of portion 128 when large volumes of oil are escaping round portion 127, where it protrudes into hole 104, as shown in FIGURE 9.

It will be noted that the extreme forward position of the rod 126, shown in FIGURE 9, is not likely ever to be attained, as in this position a large escape path for oil is available, so that the pressure required to cause this degree of leftward movement of the rod 126 is high.

A typical diagram of relief valve movement and spring deflection in relation to pump pressure is shown in FIG- URE 11.

FIGURE 12 shows a rear elevation of the pump shown in FIGURE 5, but with the cover 103 and the housing 109 removed, and with the rod 126 sectioned through the reduced portion between portions 127 and 128.

I claim:

1. A pump having impeller means and having inlet and outlet ports and a passageway interconnecting said ports in bypass relationship to the impeller means, a valve movable in one direction to close said passageway and in another direction to open said passageway, and means yieldably urging the valve in said another direction, the valve having two oppositely directed faces of different effective areas communicating with the pressure side of the pump and s disposed that the resultant force on them is in said one direction, whereby the valve is maintained against movement in said another direction so long as the pump develops a predetermined pressure, but should the pressure drop, said urging means moves the valve in said another direction to open said passageway.

2. A pump as claimed in claim 1, in which said urging means comprises spring means.

3. A pump as claimed in claim 1, and means for manually moving the valve in said one direction.

4. A pump as claimed in claim 3, and detent means for releasably retaining the valve in a position in which said passageway is open thereby rendering the pump inoperable.

5. A pump as claimed in claim 1, said impeller means being a pair of meshing gears.

6. A pump as claimed in claim 1, said valve comprising a compound plunger having larger and smaller diameter parts interconnected by a reduced stem portion of a diameter less than the diameter of either of said larger and smaller parts, said smaller part being slidably reciprocable into and out of said passageway and being disposed in said passageway when the plunger is slid in said one direction and being disposed out of the passageway when the plunger is slid in said another direction.

7. A pump as claimed in claim 6, said plunger including pressure relief means effective when said smaller part of the plunger is in said passageway to establish communication between the inlet and the outlet upon the attainment of a predetermined maximum pressure in the outlet.

8. A pump as claimed in claim 7, said pressure relief means comprising one-way valve means in the plunger permitting fiow through a passageway in the plunger only in a direction from the outlet to the inlet.

9. A pump as claimed in claim 7, said pressure relief means being provided by forming said plunger in two relatively axially movable parts, one of which parts comprises said smaller part and stem, the stem extending axially into said larger art, and means yieldably urging said smaller part toward said larger part.

References Cited by the Examiner UNITED STATES PATENTS 1,153,863 9/1915 Frank 137599.2 1,212,102 1/1917 Pipe 137599.2 1,242,245 10/1917 Rutz 137599.2 1,285,819 11/1918 Smith 103--126 1,414,323 4/1922 Barton 137-599.2 1,527,358 2/1925 Hamilton 137599.2 1,692,801 11/1928 Jensen 10341 1,723,493 8/1929 Schotthoefer 103--126 2,203,832 6/1940 Malburg 103-41 2,742,862 4/1956 Banker 103126 2,752,853 7/1956 Eames 103-42 2,858,766 11/1958 Toschkoff l0342 2,915,977 12/1959 Campbell 103-126 2,918,013 12/1959 Eames 10342 2,996,013 8/1961 Thompson et al 10342 LAURENCE V. EFNER, Primary Examiner.

Claims (1)

1. A PUMP HAVING IMPELLER MEANS AND HAVING INLET AND OUTLET PORTS AND A PASSAGEWAY INTERCONNECTING SAID PORTS IN BYPASS RELATIONSHIP TO THE IMPELLER MEANS, A VALVE MOVABLE IN ONE DIRECTION TO CLOSE SAID PASSAGEWAY AND IN ANOTHER DIRECTION TO OPEN SAID PASSAGEWAY, AND MEANS YIELDABLY URGING THE VALVE IN SAID ANOTHER DIRECTION, THE VALVE HAVING TWO OPPOSITELY DIRECTED FACES OF DIFFERENT EFFECTIVE AREAS COMMUNICATING WITH THE PRESSURE SIDE OF THE PUMP AND SO DISPOSED THAT THE RESULTANT FORCE ON THEM IS IN SAID ONE DIRECTION, WHEREBY THE VALVE IS MAINTAINED AGAINST MOVEMENT IN SAID ANOTHER DIRECTION SO LONG AS THE PUMP DEVELOPS A PREDETERMINED PRESSURE, BUT SHOULD THE PRESSURE DROP, SAID URGING MEANS MOVES THE VALVE IN SAID ANOTHER DIRECTION TO OPEN SAID PASSAGEWAY.

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