GB1590244A - Hydraulic pumps - Google Patents

Description

(54) HYDRAULIC PUMPS (71) We, DOBSON PARK INDUSTRIES LIMITED, a British Company, of Dobson Park House, Colwick Industrial Estate, Colwick, Nottingham NG4 2BX, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to hydraulic pumps.

The need often arises, for example in mining systems, for a capability to supply hydraulic fluid at two different fluid pressures or rates and our previous proposal for doing so, see patent application no. 3596/75, (Serial No. 1502012) provided a multicylinder pump with a common crankshaft for pistons thereof that are in two sets, each to provide a different one of desired pressures or rates of supply. It is an object of this invention to provide an alternative arrangement with greater flexibility of operation.

According to the invention there is provided hydraulic pumping apparatus comprising at least two hydraulic fluid pump units each of multicylinder construction with pistons thereof driven by a common crankshaft of that pump unit, a common prime mover for the pump units, and a transmission providing selective drive coupling to any one or more of the crankshafts of said pump units.

Using two pump units, their capacities may be different in terms of fluid thoughput or pressure, and the preferred drive selection allows either pump unit to be idle while the other is operating, thereby saving power and wear. Alternatively, of course, the pump units may be of the same or similar capacities either simply to cope with variations of supply requirements, say to different parts of an overall system, or to have one unit serve as a back-up to the other in the case of failure of the latter.

Another particular advantage is that such pump units will normally be readily replaceable or modified so as to allow changes of individual pump unit capacities without substantial downtime or complete pump replacement.

In a preferred embodiment, the pump unit crankshafts are coupled via respective clutches to individual gear box output shafts continuously driven in common from a prime mover output shaft. All of such shafts and crankshafts may be disposed in mutually parallel relationship with the pump units mounted side by side or one above the other for ready removal by decoupling at or from the individual clutches or a housing therefor.

Specifically, each pump unit may have separated or partitioned chambers, one a crank case mounting a crankshaft carrying piston rods moving therewith in sliding through further seals into another of the chambers to operate respective pistons in bores of or extending to a hydraulic fluid head or barrel equipped with suitable input and output valve gear operated in complementary manner by suction and pressure strokes of said pistons. For such a pump unit, it may be preferred for the pistons to incorporate hydraulic fluid flooded seals relative to their bores and/or for those pistons to be readily removed, say by unbolting, from their piston rods and replaced, possibly by a different size of piston where the bore-providing unit or each of bore providing devices is or are also readily removed and replaced.

One embodiment of the invention will now be specifically described, by way of example, with reference to the accompanying diagrammatic drawings, in which Figure 1 is an overall side view of a twounit pumping apparatus; Figure 2 is a part sectional view of a preferred selective transmission; Figure 3 is a section through a preferred pump unit; and Figure 4 is a section through a hydraulic fluid head of Figure 3.

In the drawings, a sledge like base 10 carries an electric motor 11 as a prime mover, a transmission 12 including a gear box with selective coupling clutches, and two hydraulic pump units .13, 14 for selective operation by the prime mover via transmission 12.

Output shaft 20 from the pime mover is taken via a flexible coupling 21 to an input shaft 22 rotatably end-mounted in gear box 23 and carrying a drive pinion 24 meshing with pinions 25 and 26 fixed to output shafts 27 and 28, respectively rotatably mounted in end walls 29, 30 of the gear box.

Extensions of the shafts 27, 28, or intercoupled splined shafts 31, 32, beyond end wall 30 are also rotatably end-mounted and carry sliding clutch members 33, 34 respectively interiorly splined to the shafts 31, 32 and exteriorly splined at 35 to engage in drive elements 37, 38 rotatable in clutch end wall 36 for driving pump unit crankshafts 39, 40 respectively. The sliding clutch members 33, 34 are shown operated via studs 41, 42 thereon by pivotted actuators 43, 44 with forked stud engaging ends. Clearly, either or both of the crankshafts 39, 40 may be driven at any one time and a single lever type operator could be provided, perhaps especially if the actuators were pivotted elsewhere or had extensions for central operation.

Figure 3 shows one pump unit with three similar crankshaft throws at 1200 relative displacements and one only of which is shown in detail at 50 as carrying a big end bearing 51 of a connecting rod 52 having å small-end bearing 53 to a slider 54 in one of three bores 55 formed in a partition 56 between crankshaft chamber 57 and a further chamber 58. The crankshaft is carried between end bearings 59, 60, preferably of double inclined-roller centralised types, in opposite walls of the crankshaft chamber, one with apertured closure plate 61 and the other with a mounting bell 62 for an oil lubrication pump 63, preferably feeding the big end beatings via axial and cross boring of the crankshaft.

The crankshaft reciprocated slider 54 shown in detail carries a piston rod 65 extending into the further chamber 58 via a seal 66 in a bore closure 67, and carrying a bolted-on piston 68 slidable in a sleevelike bore defining device 69 secured in wall 70 of the chamber 58. Bore 71 of device 69 tOmmunicates with a hydraulic fluid pumping chamber 72 of valve gear head or barrel 73 and there is a seal at 74, see Figure 4.

Each of the other crankshaft throws is similarly equipped to drive similar pistons in similar bore defining devices and relative to Nóther pumpiflg chambers of the head or barrel 73 as indicated in outline in Figure 3.

Turning to Figure 4, each piston 68 is of T-section carrying chevron 75 and ring 66 'sealing elements retained by a washer 57 secured by bolt 78 also fixing the piston to its piston rod 6S. The seal retaini-rg washer 77 is a clearance within the bore 71 so that the seals 75, 76 are flooded with hydraulic fluid in order to reduce piston wear by cavitation effects. Advantageously both pistons 68 and bore defining sleeves 69 are readily removed and replaced, if desired by elements of different diameters.

The valve head or barrel 73 has three bores constituting pumping chambers such as 72, each closed by plates 80 bolted at 81 and sealed at 82 but allowing ready access to the piston bolts 78. Stepped cross-bores 85 communicated with the pumping chambers 72, respectively, and house suction and supply valve seals 86, 87 to either side thereof. Supply valve element 88 cooperates with its seat 87 and has a tubular stem 89 apertured for pressurised fluid to raise the valve element 88 and pass it to chamber 90 on compression strokes of the corresponding piston 68. Positive seating bias for the supply valve element 88 is provided by a compression spring 91 and a tensioner 92 sealed and slidable in a counterbored closure 93 with setting by a locknut 94 coacting with threaded engagement of a rod 95 with the endmost part of the bore of closure 93.

Suction valve element 96 cooperates with its seat 86 and has a tubular stem 97 apertured to pass hydraulic fluid from chamber 98 to chamber 72 when the element 96 is raised from its seat 86 on suction strokes of the corresponding piston 68. Positive seating bias for the suction valve element 96 is provided by a compression spring 99 acting between valve seat 86 and locknuts 101, 102 on the end of the stem 97 or a threaded extension piece. A pump unloading device is provided as a plunger 104 operated by a piston 105 in a housing 106 sealed at 107 as a closure for the valve housing bore.

Coupling 108 for supply pressure fluid causes piston 105 to move plunger 103 to unseat suction valve element 96 for as long as that pressure is above a predetermined level settable via spring 109 and locknut 110, assuming the piston to be screwed onto the plunger 104.

Also indicated in Figure 4 are interconnecting bores 112, 113 for the suction chambers 98 and supply chambers 90 to allow single pump unit connections for hydraulic fluid inlets and outlets (not shown).

WHAT WE CLAIM IS: 1. Hydraulic pumping apparatus comprising at least two hydraulic fluid pump units each of multicylinder construction with pistons thereof driven by a common crankshaft of that pump unit, a common prime mover for the pump units, arsd a transmission providing selective drive coupling to any one or more of the crankshafts of said pump units.

2. Apparatus according to claim 1 wherein two snch pump units have different capacities.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (18)

**WARNING** start of CLMS field may overlap end of DESC **. operation by the prime mover via transmission 12. Output shaft 20 from the pime mover is taken via a flexible coupling 21 to an input shaft 22 rotatably end-mounted in gear box 23 and carrying a drive pinion 24 meshing with pinions 25 and 26 fixed to output shafts 27 and 28, respectively rotatably mounted in end walls 29, 30 of the gear box. Extensions of the shafts 27, 28, or intercoupled splined shafts 31, 32, beyond end wall 30 are also rotatably end-mounted and carry sliding clutch members 33, 34 respectively interiorly splined to the shafts 31, 32 and exteriorly splined at 35 to engage in drive elements 37, 38 rotatable in clutch end wall 36 for driving pump unit crankshafts 39, 40 respectively. The sliding clutch members 33, 34 are shown operated via studs 41, 42 thereon by pivotted actuators 43, 44 with forked stud engaging ends. Clearly, either or both of the crankshafts 39, 40 may be driven at any one time and a single lever type operator could be provided, perhaps especially if the actuators were pivotted elsewhere or had extensions for central operation. Figure 3 shows one pump unit with three similar crankshaft throws at 1200 relative displacements and one only of which is shown in detail at 50 as carrying a big end bearing 51 of a connecting rod 52 having å small-end bearing 53 to a slider 54 in one of three bores 55 formed in a partition 56 between crankshaft chamber 57 and a further chamber 58. The crankshaft is carried between end bearings 59, 60, preferably of double inclined-roller centralised types, in opposite walls of the crankshaft chamber, one with apertured closure plate 61 and the other with a mounting bell 62 for an oil lubrication pump 63, preferably feeding the big end beatings via axial and cross boring of the crankshaft. The crankshaft reciprocated slider 54 shown in detail carries a piston rod 65 extending into the further chamber 58 via a seal 66 in a bore closure 67, and carrying a bolted-on piston 68 slidable in a sleevelike bore defining device 69 secured in wall 70 of the chamber 58. Bore 71 of device 69 tOmmunicates with a hydraulic fluid pumping chamber 72 of valve gear head or barrel 73 and there is a seal at 74, see Figure 4. Each of the other crankshaft throws is similarly equipped to drive similar pistons in similar bore defining devices and relative to Nóther pumpiflg chambers of the head or barrel 73 as indicated in outline in Figure 3. Turning to Figure 4, each piston 68 is of T-section carrying chevron 75 and ring 66 'sealing elements retained by a washer 57 secured by bolt 78 also fixing the piston to its piston rod 6S. The seal retaini-rg washer 77 is a clearance within the bore 71 so that the seals 75, 76 are flooded with hydraulic fluid in order to reduce piston wear by cavitation effects. Advantageously both pistons 68 and bore defining sleeves 69 are readily removed and replaced, if desired by elements of different diameters. The valve head or barrel 73 has three bores constituting pumping chambers such as 72, each closed by plates 80 bolted at 81 and sealed at 82 but allowing ready access to the piston bolts 78. Stepped cross-bores 85 communicated with the pumping chambers 72, respectively, and house suction and supply valve seals 86, 87 to either side thereof. Supply valve element 88 cooperates with its seat 87 and has a tubular stem 89 apertured for pressurised fluid to raise the valve element 88 and pass it to chamber 90 on compression strokes of the corresponding piston 68. Positive seating bias for the supply valve element 88 is provided by a compression spring 91 and a tensioner 92 sealed and slidable in a counterbored closure 93 with setting by a locknut 94 coacting with threaded engagement of a rod 95 with the endmost part of the bore of closure 93. Suction valve element 96 cooperates with its seat 86 and has a tubular stem 97 apertured to pass hydraulic fluid from chamber 98 to chamber 72 when the element 96 is raised from its seat 86 on suction strokes of the corresponding piston 68. Positive seating bias for the suction valve element 96 is provided by a compression spring 99 acting between valve seat 86 and locknuts 101, 102 on the end of the stem 97 or a threaded extension piece. A pump unloading device is provided as a plunger 104 operated by a piston 105 in a housing 106 sealed at 107 as a closure for the valve housing bore. Coupling 108 for supply pressure fluid causes piston 105 to move plunger 103 to unseat suction valve element 96 for as long as that pressure is above a predetermined level settable via spring 109 and locknut 110, assuming the piston to be screwed onto the plunger 104. Also indicated in Figure 4 are interconnecting bores 112, 113 for the suction chambers 98 and supply chambers 90 to allow single pump unit connections for hydraulic fluid inlets and outlets (not shown). WHAT WE CLAIM IS:

1. Hydraulic pumping apparatus comprising at least two hydraulic fluid pump units each of multicylinder construction with pistons thereof driven by a common crankshaft of that pump unit, a common prime mover for the pump units, arsd a transmission providing selective drive coupling to any one or more of the crankshafts of said pump units.

2. Apparatus according to claim 1 wherein two snch pump units have different capacities.

3. Apparatus according to claim 1 or

claim 2, wherein the transmission comprises separate shafts, one for each pump unit, coupled to be simultaneously and continuously driven by a shaft coupled to the prime mover, and individual clutches for taking drive from those separate shafts to respective said pump units.

4. Apparatus according to claim 3, wherein said clutches couple directly between said separate shafts and the pump unit crankshafts.

5. Apparatus according to claim 4, wherein all said separate shafts, prime mover coupled shaft, and crankshafts are disposed in mutually parallel relationship.

6. Apparatus according to any preceding claim, wherein each pump unit comprises separated chambers, one a crank-case for said crankshaft, the crankshaft carrying connecting rods for operating sliders sealed with respect to bores therefor and carrying piston rods to move with the sliders through seals into another of the chambers in order to operate respective pistons in bores of or extending to a hydraulic fluid head or barrel equipped with hydraulic fluid suction and pressure-supply valve gear operated in complementary manner by suction and pressure strokes of said pistons.

7. Apparatus according to claim 6, wherein said pistons have hydraulic fluid flooded seals relative to their respective bores.

8. Apparatus according to claim 7, wherein each said piston, is of T-section with its cross-head element secured to its piston rod and substantially filling its bore cross-section, and its stem element having a seal retainer on its free end of an area greater than that of the stem element but less than the bore cross-section to allow passage to the seal hydraulic fluid being pumped.

9. Apparatus according to claim 8, wherein each said seal retainer is secured to its piston and that piston to its piston rod by a bolt.

10. Apparatus according to claim 9, wherein each said bolt is accessible via a different one of bores through the head or barrel.

11. Apparatus according to claim 10, wherein the last-mentioned bores allow bodily removal and replacement of the pistons and seals.

12. Apparatus according to any one of claims 6 to 11, wherein the bores for the pistons comprise sleeves fitted into a wall of said other chamber which wall serves to seat said head or barrel.

13. Apparatus according to any one of claims 6 to 12, wherein said head or barrel has separate bores each affording medially thereof a pumping chamber communicating with a different said piston and having, to opposite sides of the pumping chamber, inlet or suction and outlet or pressuresupply valves for the hydraulic fluid.

14. Apparatus according to claim 13, wherein each said valve comprises a valve element displaceable from a cooperating seat by piston action.

15. Apparatus according to claim 14, further comprising means for positively lifting the inlet or suction valve elements when pump output supply pressure reaches and exceeds a predetermined level.

16. Apparatus according to any preceding claim, wherein two said pump units are mounted one above the other.

17. Apparatus according to any preceding claim, wherein the pump units, transmission and prime mover are mounted on a sledgelike base.

18. Hydraulic pumping apparatus arranged and adapted to operate substantially as herein described with reference to and as shown in the accompanying drawings.