US2594064A - Power-transmitting system for slush pumps or the like - Google Patents

Description

April 22, 1952 c O'LEARY 2,594,064

POWER-TRANSMITTING SYSTEM FOR SLUSH PUMPS OR THE LIKE Filed Jan. 9, 1947 4 Sheets-Sheet l em Z9 H 4/ f A I 4 7C a j 5'5 4 45 IN V EN T OR.

W (jazzed M 01/6403,

h 44 By c. M. OLEARY 2,594,064

4 Sheets-Sheet 2 April 22, 1952 POWER-TRANSMITTING SYSTEM FOR SLUSH PUMPS OR THE LIKE Filed Jan. 9, 1947 April 22, 1952 c. M. OLEARY POWER-TRANSMITTING SYSTEM FOR SLUSH PUMPS OR THE LIKE 4 Sheets-Sheet 5 Filed Jan. 9. 1947 M i p R\ V2 v T k. W. Ma 5 J W a h m..\\

April 22, 1952 c, Q'LEARY 2,5945064 POWER-TRANSMITTING SYSTEM FOR SLUSH PUMPS OR THE L Filed Jan. 9, 1947 IKE 4 Sheets-Sheet 4 i i INVENTORL .E. wi a yaw.

Patented Apr. 22, 1952 POWER-TRANSMITTING SYSTEM FOR SLUSH PUMPS OR THE LIKE Charles Martin OLeary, Los Angeles, Calif. Application January 9, 1947, Serial No. 721,141

11 Claims. 1

The present invention relates to a power transmission system particularly adapted for use in driving oil well drilling slush pumps but also useful in any connection in which it is necessary to drive two or more positive displacement pumps when they are connected in series to a single fluid discharge line.

In oil well drilling operations, slush pumps are employed to circulate the drilling fluid, or mud, through the well to facilitate the drilling operation and to remove the chips and fragments cut away by the drill bit. Because of the heavy character of the mud and the high pressures and large volumes required, particularly in deep well drilling operations, the slush pumps are required to perform under exceedingly severe conditions. As a general rule during normal drilling operations, the mud is circulated by either a single pump or two pumps connected in parallel. However, in certain instances, as, for example, when the drill pipe becomes stuck, it is necessary to compound two pumps, that is connect them in series flow of relation, in order to produce an abnormally high mud pressure. Compounding of the pumps is also required in some cases when the mud becomes aerated to such an extent that the volumetric displacement of a single pump falls below the desired value and insufiicient power is available to drive it at the required higher speed against the required pressure. Steam-driven slush pumps, because of their inherent flexibility, may be successfully compounded, but the trend is away from the use of steam boilers in drilling operations and very serious difficulties have been encountered in attempting to compound internal combustion engine driven slush pumps. These difliculties are to a large extent due to the difiiculty of balancing the load between two compounded slush pumps when they are driven by separate engines or by a single engine. The unavoidable overloads imposed upon one or the other of the two compounded pumps frequently result in stripping of the pump gearing or other pump failures.

Attempts have been made in the past to overcome this difficulty by driving one of the pumps through a hydrokinetic coupler or torque converter independently of the drive to the other pump. This practice is of some benefit since it increases the flexibility of the power transmission system and tends to reduce shock loads on the hydrokinetically driven pump. However, it does not balance the load between the two pumps and, therefore, heavy overloads are still. encountered. Moreover, due to relatively wide variations in the torque load imposed on the transmission system by the slush pumps, the hydrokinetic couplers or converters are required to operate for long periods at inefficient speed ratios, with resulting overheating and injury. In addition, hydrokinetic torque converters which provide a limited variation in torque ratio at satisfactory'efficiency, if designed to operate in the maximum efiicient range during normal conditions, will impose an excessive stall torque upon the slush pumps at the time of starting or in the event a flow blockage occurs in the well.

Accordingly, it is the general object of the present invention to provide an improved slush pump drive mechanism suitable for use with an internal combustion engine power source in the form of either one or more engines which will overcome the above mentioned difliculties.

Another object of the present invention is to provide a slush pump drive mechanism which is peculiarly suited to the requirements encountered when two slush pumps are compounded.

Another object of the present invention is to provide, in a mechanism of the type mentioned, automatic or manually controlled means for changing the speed ratios of the slush pump drive as required.

Another object of the invention is to provide a single differential drive mechanism which may be used as a two-speed transmission for driving one or more pumps in parallel or as an automatic load-balancing drive for two compounded pumps.

Another object of the present invention is to provide, in a slush pump drive mechanism incorporating a hydrokinetic torque converter, means for automatically changing the gear ratio of the drive mechanism in such a manner as to maintain the speed ratio of the torque converter within its range of maximum efiiciency and automatic means for limiting the stall torque imposed upon the slush pumps by the power transmission system.

Another object of the invention is to provide an improved form of planetary transmission characterized by its compactness and high 3 torque capacity and capable of use in a wide variety of power transmission systems.

Other objects and advantages of the invention will become apparent from the following specification, the drawings relating thereto and the claims hereinafter set forth.

In the drawings:

Figure 1 is a plan view showing in a generally diagrammatic manner the preferred form of the invention;

Figure 2 is an enlarged partially sectional view of the differential transmission employed in the mechanism of Figure 1;

Figure 3 isafragmentary section taken on the line 3-3-of Figure 2;

Figure 4 is a fragmentary sectional view taken on the line 4-4 of Figure 2 Figure 5 is a fragmentary section taken on the line 5-5 of Figure 2;

Figure 6 is a longitudinal section taken through the differentially operated control switch mechanism employed to control the speed ratios. of the transmission;

'Figure '7 is a transverse section taken on the 1ine 'I--'I-of Figure 6;

Figure. 8 is a fragmentary. elevation taken on theline 8-8 ofv Figure '7;

Figure 9 shows the. circuit connections for the control switches shown in Figure 8;

Figures I is a diagrammatic illustration of the-pneumatic controlvalves for the transmission mechanism andtheir connecting air lines;

Figure '11. shows torque and eificiency curves for thetrans-missionapparatus; and

Figure 12 shows a modified form of transmissionwhich may be utilized in lieu of that shown inFigures 2' and In Figure 1-of the drawings is shown a general layout of the complete drive mechanism in a. more or less diagrammatic form. As there shown, the completeapparatus includes three reciprocating slush pumps I, 2 and-3 which may be of any desired or conventional character. The pumps are connected by suitable intake piping to a sump Affrom which they draw their fluid, andare'arrange'd to deliver fluid underpressure through the outletpipe 5'. While the pumps may be of. any desired relative size, as shown the pumps I and '2. are. larger than pump 3, this arrangement beingonecommonly employed in oil well drilling operations. Normally, the drilling fluid is supplied by eitherpump I. or pump 2 orboth o'ffthe pumps I and. 2 connected in parallel, pump 3 being astand-by pump for emergency use.

'In. accordance with the present invention,

means are'provided to connect any one of the pumps I, 2. and-3 to the outlet pipe 5, both of thepumps I and 2 in parallel to the pipe 5, or eitherof. the pumps I and'.2 in series or parallel withthe pump 3, to the discharge pipe 5. Thus, pumpIis connected 'to the sump by an intake pipe. 6 containing a shut-off valve I; and the vertical. discharge pipe 8' of "the pump I, which'contains a shut-off valve 9, is-connected to a branch pipe I'II'i of the discharge pipe 5. Pipe I0 is also connectedto'the.dischargepipe I I of the pump 2,

' thellatter pipe containing a shut-off valve I2. A

shut-oifvalve I'3Icontrol's communication between the branch pipe Inland the discharge pipe 5. The discharge'pipe I4 of pump 3 containsashut-off valve I5 and is connected to a branch pipe I6 which,. in turn, connects the inlet pipe I! of pump 2 with the discharge pipe -5. A pair of shut- 0ff=valves I8. and If9.is.positionedin branch pipe 'I'G'. 'Int'ake pipe H for pump Zcontains a shutoff valve 20 between the sump 4 and the point of connection of pipes I6 and IT. The pump 3 is provided with an intake pipe 2 I containing a shutofi valve 22. Between the pump 3 and the shutoff valve 22, a branch line 23 connects the intake pipe 2I with the branch pipe I0. Pipe 23 contains a shut-off valve 24. Pipe '25 connects the intake pipe 6 of pump I with the branch pipe I6 and contains a shut-off valve 26.

As a result of the above connections and valves, any one of the pump connections shown on the following table may be provided as required. On the table, the letter S in the columns under the various valves means that, for the condition corresponding to the horizontal' line in which the letter appears, the valve is shut; the letter 0 indicates that the valve is open; and the absence of any letter indicates that the position of the valve is immaterial. It will be noted that the table lists pumps I and 3 in series and also, separately, pumps 3 and I in series. A duplicate listing of the series connections of the pumps 2 and 3' also appears. This is due to the fact that in the series connection, either of the two pumps may be connected in advance of the other in the direction of fluid-flow.

Valves g gig 9 12 13 15 18 19 20 22 24 26 1 1and2parallel O O O O S O S 2 land3parallel 0 0- s 0 0 s 0 o s s j2and 3para11el s 0 0 0 s 0 0 0 s s 4 land3series O' O S S .0 S O S O S 5 3and 1series S' O S O O S S l O S O 6 2and3serics l S O S O S O O S O S 7 3and2series. is' .0 .0 0 0 s s 0 s s 8 O 0' S O S- S 9 2'alone 'S '0 O S S S l0 3alone S' O S O O S In accordance with the present invention, the three pumps I, 2 and 3 are connected to a novel form oftpowertransmission', indicated generally at ZI'in Figure 1, in any suitable manner, as by chain drives. Thus, the drive sprocket 26 of pump I is 'connectedbymeans-of a chain, indicated in dottedlines'at 29, to a sprocket 3B; the drive sprocket 3I' of pumptis connected by means of'a chain 32 to-a sprocket 33; and the drive sprocket 34 ofpump 2 is connected by means of a chain'3'5' to a spro'cket'36'. All three of the sprocketstfl, 33 and 36 are adapted to be-driven by the transmission 21,. in the manner hereinafter more fully pointed out. Power-is supplied to the transmission 27 through a sprocket 31 which is connectedby' means of a chain 38 to'a sprocket '39 which is fixed to" the output shaft 40 of a hydrokinetic torqueconverter, indicated more or less diagrammatically at4I. The'input shaft "42 of the converternl constitutes the output shaft of an internal combustion engine 43 or any other suitable source of power. The torque converter'4I' is'preferably'provided with a differentially operatedcooling' fan and radiator unit d l'adapt'edto' cool the operating liquid of the converter'inapproximate proportion to the rate of heat generated therein. The'differential cooling mechanism per se forms'nc part of the present invention and, consequently, for a more de- 7 tailed illustration and" description thereof, reference 'may'be had to 'applicants prior copend-ing application, Serial No. 665,626; filed May 2, 1946 now'Patent Number2,589,l-20, dated March 11,

19.52; V The shaft '40 passes throughan" elongated-housa planet cage, indicated generally at 60.

ing 45, a portion of which is shown in the drawing, and within the housing carries a freely journaled sprocket 46 which may be connected to the shaft 48, as desired, by a pneumatically operated clutch 4''. The sprocket 46 carries a chain 48 which may be connected to one or more engine-hydrokinetic torque converter units identical to the single unit illustrated in the drawings. Thus, when it is desired to utilize two or more engines to drive the slush pumps, this may be accomplished by engaging clutch 41 and supplying power to shaft from additional engines.

The construction and arrangement of the transmission mechanism 27 is best illustrated in Figures 2, 3, 4 and 5. Thus, as shown in Figure 2, the input sprocket 37 is freely journaled on a tubular shaft 49 which, in turn, is journaled in casing 59 by means of roller bearings 5| and 52. The sprocket 51 is adapted to be connected to the shaft 49 by means of a pneumatically oper ated clutch, indicated more or less diagrammatically at 53, which may be supplied with air under pressure through a line 54 connected to a stationary manifold associated with the hearing 55 for the outer end of tubular shaft 49, in the usual manner.

The transmission 21 is of the differential type and the shaft 49 carries a sun gear 56 which meshes with a plurality of planet gears ,51, each of the latter constituting one of a pair of cluster gears including a larger planet gear 58. The planet gear clusters, one of which is shown in section in Figure 2, are each journaled on coaxial pins 59 which are fixed at their opposite ends to The planet cage is fixed by means of a web 8! to a shaft 62 which is journaled within the previously mentioned tubular shaft 49 and projects beyond the latter at both ends. A total of 8 sets of cluster gears is provided in the transmission in order to distribute the load over as many gear teeth as possible, As best shown in Figures 2 and 5, the planet cage is in the form of an integral casting, including the web 6|, a pair of parallel annular side plates 66a and 60b, which are connected together and to the web 6! by a plurality of axially extending webs 60c, and a cylindrical portion 60d which extends axially from the side plate 601) over the smaller gears of the gear clusters 58. Each of the larger gears 58 of the planet gear clusters meshes with a ring gear 63 which is fixed in any desired manner to the interior of a. cylindrical housing 64 which, in turn, is connected by an end flange 65 to a tubular shaft 66.

In order to facilitate proper meshing of the cluster gears 58 with the ring gear 63, the latter preferably has a slightly floating connection to the housing 64. manner best shown in Figure 3, by providing a plurality of external teeth 61 on the ring gear 83 which mesh somewhat loosely with internal teeth 68 formed on the interior of the housing 64. The shaft 66 is journaled by means of bearings 69 in the housing 50 of the transmission and carries at its outer end the previously mentioned drive sprocket 33 for the pump 3. The sprocket 33 is freely journaled on the shaft 66 but may be connected thereto by an air operated clutch Hi when desired, the clutch H1 being similar in construction and operation to the previously mentioned clutch 53.

The sizes of the gears 55, 51, 58 and 63 are preferably so selected as to provide a speed ratio between the shafts 49 and 62 of 2 to 1 when the housing 64 is held stationary, and selectively This may be achieved, in the housing 64 to the casing 21 in order to establish the 2 to 1 drive ratio or to the planet cage 60 in order to establish a l to 1 drive ratio between the shafts 49 and 62.

As best shown in Figure 5, means for fixing the housing 64 to the casing 55 of the transmission comprises a plurality of clutch or brake block mechanism, one of which is shown in section in Figure 5. These mechanisms include a one-way clutch or brake block H which is formed of a suitable friction material and positioned within a pocket 12 formed in the casing 50. The inner surface of the brake block H :is adapted to frictionally grip the exterior of the cylindrical housing 84. The outer sides of the pocket 12 are closed by castings 13 having fiat inner surfaces 14 adapted to bear against the outer surfaces of the brake block I I. A helical spring 15 normally urges the brake block it in a direction to wedge it between the surface 14 and the exterior surface of the housing 64 and thus frictionally hold the housing 64 against rotation. Each casting I3 contains a cylindrical opening 16 which receives a piston Tl andwhich is closed at its outer end by means of a plug 18 having an air pipe connection 19 by means of which air under pressure may be supplied to the interior of the cylinder. The piston 71 is normally urged toward the plug 18 by means of a helical spring 80. A piston rod 8|, fixed-to the piston, carries a lug 82 which is adapted to engage the end of the brake block H. Spring 88 normally holds the parts in the position shown, in which the lug 82 is out of engagement with the brake block 7!. In this position, the spring '15 wedges the block between the housing 64 and the surface 74.

However, upon application of air under pressure to the cylinder 75, the piston and, consequently, the lug 82 are shifted downwardly, as viewed in Figure 5, causing the lug 82 to engage the brake block H and shift it out of engagement with the housing 64. In that connection, it should be noted that housing 64 tends to rotate in a direction opposite to that of sun gear 55, i. e. clockwise, as viewed in Figure 5, and, consequently, assists the wedging action induced by spring I5. As a result, in the absence of application of air under pressure to the line 19, housing 64 is held stationary and the transmission is maintained in its 2 to 1 ratio. When the air is applied to line 19, housing 64 is free to rotate with respect to the transmission casing 56.

The supply of air to all of the cylinders I6 is preferably controlled by means of a conventional three-way valve 83, shown diagrammatically in Figure 10. The valve 83 is provided with an intake line 84 adapted to be connected with a source of air under pressure and an exhaust line 85. The valve is operated by a solenoid, indicated diagrammatically at 8B, which, on onergization, places the valve in the position in which it connects lines 84 and 19. When the solenoid is de-energized, line 19 is connected to the exhaust line 85.

The means for locking the housing 64 to the planet cage 59 comprises a cone clutch member 8'! adapted to frictionally engage an. internal cone clutch surface on the housing 54. lhe cone clutch element 8'. is connected by a plurality of helical splines 88 to the cylindrical portionfiild of the planet cage 60. As best shown in the fragmentary sectional view of Figure 4, the helix angle of the splines 88 is such that the rotary force imposed upon the clutch element 81 by sprocket 30 which drives pump I.

its frictional engagement with the housing 64- tends to cause releasing movement of the clutch element, i. e. movement to the left, as viewed in Figure 2. *Such release movement is assisted by a plurality of axially acting circumferen-tially spaced helical springs positioned between the planet cage 60 and an inwardly directed flange 89 on the clutch element 81. A portion of one of these springs is illustrated fragmentarily at 90 in Figure2.

The means for shifting the clutch 81 into .engagement with the housing 64 comprises an annular piston 9| fitted within an annular recess formed by a pair of angle members 92 and 93 carried by the end wall of the casing 50. A plu rality'of ball thrust bearings 94 is positioned between the piston SI and the flange 89 of the clutch element 81. As a result of this construction, application of air under pressure to the annular cylinder through line 95 will'efiect engagement of the clutch 81 and thereby lock the housing 64 to the planet cage 60.

The air required to operate the annular piston 9| is supplied by a separate three-way-control valve 96 which is identical in construction and mode of operation to the previously described valve 83. Thus, valve 96 is also connected to the air supply line 84 and is operated by a solenoid 91. When the solenoid 91 is energized, valve 96 connects lines 84 and 95; when it is de-energized,

line 95 is connected to the exhaust line 85. As hereinafter set forth in greater-detail, means are provided for controlling the operation of valve 96 either automatically or manually.

The internal shaft-.62 of the trasnmission projects beyond the bearing 55 and has journaled on its projecting end the previously mentioned The sprocket may be connected to the shaft 62, when desired, by means-of a pneumatically operated clutch 98. Shaft 62 also projects at the opposite side of the transmission beyond the bearing 99 for the outer end of tubular shaft 66 and has journaledthereon the previously mentioned drive sprocket 36 for pump 2. the shaft 62, when desired, by means of a pneumatically operated clutch I00. Shaft 62 also carries a brake'drum IIJI with which isassociated a conventional brake band I02 by means ofwhich the shaft 62 may be held against rotation, when desired.

As a result of the above construction, it is possible, by controlling the transmission 21 and the clutches 10, 98 and I00, to drive either pump 3 or either or both of the pumps I and 2 at either one of two speed ratios with respect to the speed of the input sprocket 31. Thus, when neither of the'solenoids 96 and 91 is energized, the transmission 21 will be in its lower gear ratio for rotating shaft 62 in the same direction but at a speed less than that of the input shaft 49. Either or both of the pumps I and 2 may beconnected to the shaft 62', as desired, by means of the clutches 98 and I00. When solenoid 91 is energized, the cone clutch element 81 is engaged and the transmission 21 locked in its 1 to 1 or direct drive ratio, in which the shaft 62 rotates in the same direction and at the same speed as the sprocket 31. The fact that housing 64 rotates in a counterclockwise direction when cone clutch 91 is engaged, automatically disengages the brake blocks 1I-. Similarly, pump 3 may be driven at a 1 to 1 speed ratio by engaging the clutch 10 and thecone clutch element 81'. Pump 3 may also be driven at a higher speed ratio by The sprocket 36 may be connected to engaging the brake I92 while the brake blocks H and cone clutch 81 are both disengaged. The

higher speed ratio in this case is in the 0pposite direction and will be an overdrive, and

it will be necessary to disengage brake blocks H by energizing solenoid 86. While the shaft 66 will rotate in one direction at the 1 to 1 ratio and the opposite direction at the higher ratio, that will cause no difliculty when the transmission is utilized to drive reciprocating pumps since the direction of fluid flow is the same for both directions of rotation.

In addition to the above, an important feature of the present invention resides in the fact that the transmission 21 may be utilized to differentially drive the pump 3 with either one of the pumps I and 2. This is highly desirable under certain circumstances, particularly when the pump 3 is connected in series or compounded with either of the pumps I and 2 in order to develop an abnormally high fluid pressure for special purposes. Thus, if, for example, it is desired to compound pumps I and 3, clutches 9'8 and 10 are engaged and the brake blocks 1| and clutch 81 are disengaged. Under these circumstances, power supplied to the input shaft 4-9 of the transmission will be differentially transmitted to the shafts 62 and 66 and thus to the pumps I and 3. This arrangement has decided advantage because it insures that the torques supplied to the two pumps will always bear the same relation to each other and, consequently, the pressure rise in each of the two pumps will always bear the same relation to each other. In this connection, it is preferable to have each of the pumps develop half of the total pressure rise and, accordingly, the gear ratios of the transmission 21 and the drive connections from the transmission to the two pumps should preferably be so correlated with the effective crosssectional areas of the pump plungers that the relation between the torque delivered to the crankshaft of one of the pumps and the crosssectional area of the plunger of that pump is the same as the relation between the torque delivered tow the crankshaft of the other pump and the cross-sectional area of the plunger of the other pump.

The different pump drive not only has the advantage that it automatically fixes and maintains the relation between the pressure rise' in the two pumps a constant value, but it accomplishes that result While permitting an independent variation in the relative speeds of the two pumps. Consequently, the speeds of the pumps will automatically adjust themselves to the extent necessary to maintain the relative loads on the two pumps constant. As a result, there is no danger of either pump being subject to an overload. Where there is a difference in the sizes of the two differentially driven pumps, as in the illustrated embodiment of the inven tion, the smaller pump will, of course, operate at a higher speed than the larger pump and, if

the pressure rise in both pumps is the same it .1 converter or its equivalent in the drive connection which they provide, but because they are effective to absorb shock loads and thus reduce the danger of pump failures resulting from momentary overloads, however, induced. Accordingly, in the preferred form of the invention illustrated in the drawings, the transmission 21 is driven from an internal combustion engine through a hydrokinetic torque converter.

However, torque converters have two disadvantages as applied to a slush pump drive: first, their i efficiency is low except over a limited range of speed ratios; and, second, if they are so designed and connected to the slush pumps that they will deliver adequate torque at an efficient speed ratio for normal operation, they are likely to impose an excessive overload on starting or at very low speed ratios. A further feature of the present invention resides in the provision of automatic control means for the transmission 21 so constructed and arranged that it will overcome both of the above mentioned difficulties. This result is achieved by properly correlating the two speed ratios of the transmission 2"! with the efficiency curve of the torque converter utilized and by automatically shifting the transmission in such a manner as to increase the speed ratio range of maximum efficiency for the complete transmission mechanism on one hand and reduce or limit the torque transmitted to the pumps on the other, The mechanism by which this result is accomplished is best shown in Figures 6, 7, 8, 9 and 10, and the performance characteristics of the mechanism are shown graphically in Figure 11.

Thus, as shown in Figure 9, the solenoid 97, which controls the operation of the valve 96, is connected in series with a pair of parallel connected switches I03 and I04 across a pair of electric supply lines I05 and I06. A manually operated switch I01 is provided for selectively connecting the line I05 to the solenoid 91 through the switches I03 and I04 or independently of the switches I03 and I04 to either the solenoid 9'! or the solenoid 86, the first connection being established by engagement of the switch I0I with the contact I08, the second by engaging the switch I01 with the contact I09, and the third by engag ing the switch III! with a contact IIO. As a result of these connections, when the switch I01 engages contact I08, solenoid 91 is energized when either of the switches I03 and I04 is closed. As previously indicated, the energization of solenoid 91 places the transmission 21 in its high or direct drive ratio, while de-energization of both of the solenoids 8S and 9? places the transmission in its low gear ratio.

It is necessary, in order to achieve the desired results, to correlate the two speed ratios of the transmission 27 with respect to the efficiencyspeed ratio curve of the hydrokinetic torque converter employed. While such curves vary to some extent between converters of different designs, one representative curve is indicated at H2 in Figure 11. It will be noted from curve II2 that the efficiency of the torque converter is relatively high throughout a speed ratio range between .33 and .66, but drops off rapidly on either side of that range. The lower of these speed ratios, namely is hereinafter referred to as the minimum efficient speed ratio of the converter, while the to as the maximum efficient speed ratio. ,It will higher ratio, namely .66, is hereinafter referred be noted that for the converter whose curve is illustrated by the line I I2, the ratio between the maximum and minimum efficient speed ratios is 2 to 1. Accordingly, in accordance with the present invention, the ratio between the two speed ratios of the transmission 21 is also made approximately 2 to 1. Since the high speed ratio of the transmission 2'! is 1 to 1, this means that the low speed ratio should be approximately 2 to 1. In other words, in low gear, shaft 49 will rotate two revolutions for each revolution of the shaft 62. With this correlation between the speed ratios of the transmission and the maximum and minimum efficient speed ratios of the converter, it is possible to extend the speed ratio range of high efficiency by shifting the trasmission from its 2 to 1 to its 1 to 1 ratio when the speed ratio of the converter reaches or exceeds its maximum efficient ratio and by returning the transmission to its lower speed ratio of 2 to 1 when the speed ratio of the converter falls below its minimum efiicient speed ratio. It is also possible to reduce the stall or maximum torque delivered by the transmission and torque converter by shifting the transmission to its higher speed ratio when the transmission is in its lower speed ratio and the speed ratio of the torque converter falls below its minimum efficient ratio. In accordance with the present invention, this result is performed automatically by a differential operation of the control switches I03 and I04.

Thus, as shown in Figures 6, 7 and 8, there is provided a differential switching device comprising a base II3 which supports a pair of housings I I4 and I I 5, which housings, in turn, support and journal five axially aligned shafts H6, H1, H8, H9 and I20, the shafts II! and H9 being preferably journaled on antifriction bearings, indicated generally at I2I and I22, respectively. Shaft II8 carries a pulley I 23 which is connected by means of a belt I24 to the input shaft 42 Ofthe torque converter 4|, as best shown in Figure l. Consequently, shaft I I 8 rotates at a speed proportional to engine speed. Shaft I I6 is connected by means of a flexible shaft, indicated generally at I25, to the end o'f'shaft I52, as best shown in' Figure 2. Consequently, shaft I I6 is driven at aspeed proportional to the speed of the output shaft '62 of the transmission 27. Shaft I I6 carries a gear I28 which meshes with a gear I29 on a countershaft I30 carried by the housings H4 and H5. A gear I3I on shaft I39 meshes with a gear I32 on the shaft I20. Consequently, the shaft I20 is also rotated at a speed proportional to the spe'ed of the output shaft'fiZ of'the transmission.

In order to actuate the control switches I03 and I04 at the desired speed ratios, the geared speed ratio'between the output shaft 62 of the transmission andshaft IIB of the differential switch actuating device is three times the speed ratio between the shaft 42 and the shaft II8. Consequently, shafts H6 and H8 will rotate at the same speed but in opposite directions when shaft 62 is rotating at one-third of the speed of shaft 42. The gears I28, I29, I3I and I32 are of such size that the shaft I20 rotates at twice the speed of shaft III; and in the same direction. Consequently,'shafts H8 and I20 will rotate at the same speed but in opposite directions when the speed of shaft 62 is one-sixth of the speed of shaft 42. Shafts H6 and I II are connected by-aneddy current clutch,indicatedgenerally at I33, the clutch comprising a housing I34 formedof electrically conductive material, such as aluminum or copper, fixed to the shaft I11 and a multipole manner; As is well known, the eddy currents induced in the housing I34 by rotation of the multipole permanent magnet I35 create an electromotive force tending to rotate the housing I34'in thesame direction asthe magnet. The device. therefore, transmits a rotating torque which is proportional to the difference between the speeds of the shafts] I6 and Ill.

The shafts I I1 and I I8 areconnected by a similar eddy current clutch I31 comprising a housing I30 and a multipole permanent magnet I39. Eddy current clutch I3'I transmits a slipping torque from the shaft II8 to the shaft I H which is proportional to the differencein speeds of the two. shafts. Since shafts H6 and H8 are rotated in opposite directions, the forces transmitted from them to the shaft III by the two eddy current clutches are acting in opposite directions and tending to balance each other.

.terial, which projects through a slot MI in the housing H 5 and-carries at its outer end the switch contact element I03-wh-ich is adapted to close an electrical circuit between a pair of contacts I43 and I44. The tendency of the housing I38 to 1'0- tatein the same direction as the shaft I I3 under :the above described circumstances holds the contact I03 out of engagement with the contacts I43 and I44. A light spring I45 also assists in holdingthe contact in open position. However, itwill beapparent that if. at any time the speed of shaft 52. exceeds one-third of the speed of shaft 42,

shaft. II 6 will rotate. at a higher speed than shaft 1 I8 and the net :force acting upon the shaft II! will tend to rotate that shaft in the opposite disection and thereby close the switch contact I03. Consequently, the contact I03 is always open when. the ratio of speeds of the shafts 62 and 42 is less thanl to 3, and is always closed when the :ratio is above 11 to 3.

Shaft H9 is. similarly connected to shafts H8 and. I10 by means of .apair' of eddy current clutches 1.46 and I4], .andtheahousingof the eddy current clutch I146 carries. a pin I48 whichsupports the switch contact I304. .It will be noted from Figure 8 that the contact I04. is reversely arranged with respect to the previously described contact 10.3. Consequently, when the shaft II8 .is;rotating :at a higherspeed than the shaft I20, thenet force transmitted to the shaft. I I9 by the two eddy current clutches tends to cause the switch-contact I04 to engage stationary contacts 1'49 :and I50. Therefore, switch contact I04 is always closed when the speed of shaft 62 is less than one-sixth of the speed of shaft 42, and is always open when the speed of shaftIiZ is more than one-sixth of the speed of shaft 42.

:Since SWiiEQh' CQHtaCtS. I03. and I04 are-connected inparaliel and closure of either switch will energize. the solenoidfil of Figurefi, itqwill be apparent that, .asaresultof. the above icon.-

struction, the solenoidv 91 will be ener ized when the speed of shaft .62 is less than one-sixth of the speed of shaft 42. and more than one-third of the speed of'shaft 42. Both of the. contacts I03 and I104 will .be openedand, therefore, thesolenoid 9'! will be .de-energized when the speed of shaft 62 is intermediate one-third and one-sixth of the speed of shaft 42, and this will place the transmission inits. low gear ratio.

The resulting performance characteristics of I the drive mechanism are shown graphically in Figure 11. As'there indicated, the curve I'I'2is the efficiency curve of the torque converter utilized in. the combination, and line I5I represents the torque ratio of the converter and transmission combination when the transmission is in its '1 to 1 ratio. The lines I52 and I53 represent the chi.- ciency and torque ratio curves for the combina: tion when the transmission is in its low gear or '2 to 1 ratio. The differential switch operating mechanism serves to maintain the transmission in its high gear or 1 to 1 ratio at speed ratios below-.16 and above .33, and to shift the transmission into its low gear ratio at intermediate speed ratios. Therefore, on starting, the torque ratio of the torque transmitted to shaft 02 will follow the line I5I down to the speed ratio of .16, at which time the transmission is shifted to its low gear ratio and the torque ratio will then jump to the torque ratio curve I53. As the speed of shaft 56 continues to increase, the torque-ratio will drop off along the line I53 until a speed ratio will drop off along the line I53 until a speed ratio of .33 is reached and the transmission is returned to its 1 to l or high gear ratio, whereupon, on further increases in the speed of shaft 02, the torque ratio will return to and follow the curve I5I. If the load on the shaft 52 increases and thereby reduces the speed of the shaft below the speed ratio of .33, the transmission will be returned to its low gear ratio and the torque ratio will then follow up the curve I53 until the overall speed ratio reduces to .16.

It will be observed that by automatically maintaining the transmission in its high gear ratio at low overall speed ratios, the mechanism limits the total torque transmitted to the shaft 62, which otherwise might be excessive at exceedingly low speed ratios because of the high stall torque transmitted by the hydrokinetic torque converter. It will also be observed that by returning the transmission to its high speed ratio when the overall speed ratio reaches and exceeds .33, the mechanism extends the speed ratio range over which the "torque converter operates at high eificiency.

It will be appreciated that the speed ratios at which the transmission shifts occur may be selected to give any desired performance characteristics, and that the speed ratios provided by the transmission may be altered to conform, in the manner described above in connection with the illustrated embodiment of the invention. In addition, it will be appreciated that for torque converters having different forms of efficiency curves, it will ordinarily be necessary to select different speed ratios for the shift points in order to obtain optimum results.

As previously indicated'the switch 801 may be actuated at any time to disconnect the automatic shifting control. The transmission can then be controlled manually by moving the switch arm. into and out of engagement with either of the contacts. I09 and H0. Thus, if desired,v the pumps may be started or operated in. low gear by engaging Contact. I30. Thereafter, the auto matic control may be restored to operating condition by engaging the switch arm with contact I68.

The form of transmission shown in Figure 2, if constructed to provide a 2 to 1 ratio between the shafts 49 and 62 in low gear, will provide a l to 2 overdrive from the shaft 49 to the shaft 66 when shaft 62 is held stationary by brake I02. Consequently, when driving pump 3, alone, the low gear ratio of the transmission is a direct or 1 to 1 drive ratio in the opposite direction and, therefore, the automatic gear shifting mechanism of Figures 6, 7 and 8 cannot be utilized.

When it is desired to differentially drive the shafts 66 and 62, switch III? is placed in engage- 1 ment with contact H0, in order to energize solenoid 86 and de-energize solenoid 01. Under these conditions, a transmission designed to provide the ratios specified above will deliver to the shaft 56 one-fourth as much torque as is delivered to the shaft 62. Consequently, it will be necessary to provide a step-down speed ratio. drive between the sprocket 33 and the drive sprocket 3| of pump 3, which will give a higher speed reduction than that provided by the sprockets 36 and 34 in order to avoid driving the pump 3 at an excessive speed. The particular ratio provided will depend upon the relative sizes of the two pumps. Thus, if pumps 2 and 3 are compounded and the crosssectional area of the plunger in pump 2 is twice that of pump 3, it will be necessary to drive pump 3 at twice the speed of pump 2. Since the sprocket 33 is already tending to rotate at four times the speed of sprocket 36 and this is more than the desired amount of increase in speed, it will be necessary to utilize twice as much speed reduction between sprockets 3| and 33 as is provided between sprockets 34 and 36.

The relatively great difference between the torque delivered to sprocket 33 and that delivered to sprocket 36 may be avoided, if desired, by utilizing the slightly modified form of transmission illustrated fragmentarily in Figure 12. The transmission of Figure 12 differs from that of Figure 2 in that the power input is connected to t the planet cage and the two output shafts are connected, respectively, to the sun gear and the ring gear. With this arrangement, the output shaft which is connected to the ring gear will receive one-half as much torque as the output shaft which is connected to the sun gear, and the high gear ratios to both shafts will be overdrives.

Thus, as shown in Figure 12, planet cage I54,

which is identical in construction to the planet cage 60 previously described, is connected to a tubular shaft I55 which carries a sprocket I56 adapted to be connected to the source of power. The sun gear I5'I is connected to an internal shaft I58 which carries a pair of sprockets I50 and I60 which may be clutched to the shaft I58, as desired, by means of pneumatically operated clutches IGI and I62, respectively. The ring gear housing I63 is connected by means of a plate I64 to a tubular shaft I65, which carries a sliding clutch element I66 adapted to clutch a sprocket I61 to the shaft I65. A similar clutch element I63, which is splined to shaft I58, may be utilized to clutch the sprocket 56! to the shaft I58, when desired. It will be understood that sprockets I59, I 60 and I6? are connected by means of chains to the three slush pumps. Preferably, the smaller slush pump, if there is any difference in size, is connected to the sprocket I61 and the two larger pumps to the sprockets I55! and I60.

The cone clutch element I69, which is similar in construction and mode of operation to the clutch element 81 of Figure 2, has an inwardly extending flange I10 which extends to a position adjacent an annular piston III which operates to effect clutch engagement under the influence of air under pressure supplied through a passageway I'I2 in the shaft I58.

The operation of the transmission illustrated in Figure 12 is identical to that previously described exceptthat, when driving shaft I58, the low gear ratio is a 1 to 1 or direct drive, while the high gear drive is an overdrive. Consequently, when the automatic shifting mechanism of Figures 6 through 8 is employed, it will be necessary to reverse the contacts I03 and I04 with reference to their co-operating stationary contacts in order to effect an opening of the switches under the circumstances in which they close during the operation described above. In addition, the stationary contacts of the switches I03 and I04, instead of being connected in parallel, as shown in Figure 9, must be connected in series, and the valve 96 utilized to supply air to both the cone clutch and the brake block cylinders simultaneously. In that case, the solenoid 91 will only be energized when both of the switches are closed, and it will be de-energized when either of the switches is opened.

Both forms of transmission may be used for other purposes with advantage. Each is capable of providing two different speed ratios in one direction and a reverse drive. Three shafts are employed in each transmission: one connected to the sun gear, one to the ring gear and one to the planet cage. By driving any one of these three shafts and takin power off either of the other shafts, a wide variety of speeds is available, particularly if selectively operable brakes, such as the brakes II and I62, are provided on the two output shafts and clutch means are provided for selectively connecting the load to those two shafts.

While only two forms of the invention are illustrated and described herein, it will be apparent that variations in the construction and arrangement of the parts may be indulged in without departing from the spirit of the invention. Thus, the improved planetary transmissions per se are of advantage and utility in any application requiring the use of a two-speed transmission with or with the optional differential drive. In this connection, they are peculiarly suited to the heavyduty requirements of oil well slush pump, rotary table or hoisting drum drives. While the transmission may be employed without a. hydrokinetic torque converter, peculiarly advantageous results are achieved with the complete combination, including the automatic transmission shiftlng mechanism, which extends the effective speed ratio range of the complete drive and operates automatically to limit overloads. I

What is claimed is;

1. In combination, a pair of positive displacement pumps adapted to be connected in series flow relation, 2. driving shaft adapted to be connected to a source of power, a pair of driven shafts, means connecting said driven shafts respectively to said pumps, and a differential gear set connecting said three shafts.

2. In combination, a pair of positive displacement pumps, a pump discharge conduit, means selectively operable to connect said pump individually or in series flow relation to saidconduit, a driving shaft adapted to be connected to" a source of power, a pair of driven shafts adapted to be-conneoted respectively to said pumps, a differential gear set connecting said three shafts. and brake means on one of said driven shafts adapted on operation to hold said shaft against rotation and thus permit driving of the other driven shaft by said differential.

3. In combination, a pair of positive displacement pumps, a pump discharge conduit, means selectively operable to connect said pumps individually or in series flow relation to said conduit, a driving shaft adapted to be connected to a source of power, a pair of driven shafts adapted to be-connected respectively to said pumps, a differential gear set Connecting said .three shafts, and selectively operable means for connecting said driven shafts in a fixed driving relation to each other.

.4. In combination, a pair of positive displacement pumps, a pump discharge conduit, means selectively operable to connect said pumps individually or in series flow relation to said conduit, a driving shaft adapted to be connected to a source of power, a pair of driven shafts adapted to be connected respectively to said pumps, a differential gear set connecting said three shafts, brake means on one of said driven shafts adapted on operation to hold said shaft against rotation and thus permit driving of the other driven shaft by said differential, and selectively operable means for connecting said driven shafts in a fixed driving relation to each other.

5; In combination, a pair of positive displacement pumps, a pump discharge conduit, means selectively operable to connect said pumps individually or in series flow relation to said conduit, 2. driving shaft adapted to be connected to a source of power, a pair of driven shafts, means connecting said driven shafts respectively to said pumps, a differential gear set connecting said three shafts, means selectively operable to hold one driven shaft stationary to effect a drive of the other driven shaft at one speed ratio, and means selectively operable to connect said driven shafts in fixed driving relation to each other to effect a drive of said other driven shaft at another speed ratio, whereby both pumps may be driven differentially from said'driving shaft or one pump may be driven at either one of two speed ratios.

6. In combination, a pair of positive displacement pumps, a pump discharge conduit, means selectively operable to connect saidpumps individually or in series flow relation to said conduit, a driving shaft adapted to be connected to asource of power, a pair of driven shafts, independently disengageable power transmitting devices for connecting said driven shafts respectively to said pumps, a difierential gear set connecting said three shafts, means selectively operable to hold either of said driven shafts stationary and thereby effect a drive of the other driven shaft, andimeans for locking said driven shafts together to'effect a simultaneous drive thereof at a different speed ratio, whereby both driven shafts .may .be driven differentially or either driven shaft may be driven alone at either one of two speed ratios.

7. In combination, a pair of positive displacement pumps, a pump discharge conduit, means selectively operable to connect said. pumps individually or inseries fiow relation to said conduit, a-driving shaft adapted for connection to a source of power, a pair of driven shafts, means for-connecting the driven shafts respectively to the pumps, and a differential gear set connecting said threeshafts, said differential and connecting means providing torque ratios between the -driv ing shaft and the pumps which will enable both pumps to develop approximately the same pressure when they are connected in parallel or each pump develops approximately the same pressure rise when they are connected in series.

8. In combination, a hydrokinetic torque converter having an input shaft adapted to be connected to a source of power and having an output shaft, a two-speed ratio transmission having itsinput shaft connected to said torque converter output shaft and having an outputshaft adapted for connection to a power consuming device,

and automatic means for shifting said transmission from its lower to its higher speed ratio when the speed ratio of the converter falls below a predetermined value, said means including a power operated shifting mechanism and a speed ratio responsive control device operatively associated with the input and output shafts of the converter.

9. In combination, a hydrokinetic torque converter having an input shaft adapted to be connected to a source of power and having an output shaft, a two-speed ratio transmission having its inputshaft connected tosaid torque converter output shaft and having an output shaft adapted for connection to a power consuming device, and automatic means for shifting said transmission from its lower to its higher speed ratio when the speed ratio of the converter increases beyond apredetermined ratio above that of maximum efliciency and vice versa when the converter ratio falls below said predetermined ratio, said automatic means being effective to shift said transmission from its lower to its higher ratio when the speed ratio of the converter falls below a second predetermined ratio below that of maximum efficiency and vice versa when the converter ratio exceeds said second predetermined ratio, said automatic means including a poweroperated shifting mechanism and a speed ratio responsive control device operatively associated with the input and output shafts of the converter.

10. In combination, a hydrokinetic .torque converter having an input shaft adapted to be connected to a source of power and having an output shaft, a two-speed ratio transmission having itsinput shaft connected'to said torque converter output shaft and having an output shaft 7 adapted for connection to a power consuming device, and automatic means for shifting said transmission from its lower to its higher speed ratio when the speed ratio of the converter increases beyond a predetermined ratio above that of maximum eflioiency and vice versa when the converter ratio falls below said predetermined ratio, said automatic means being effective to shift said transmission from its lower to its higher ratio when the speed ratio of the converter falls below a second predetermined ratio below that of maximum efficiency and vice versa when the converter ratio exceeds said second predetermined ratio, said automatic means including a poweroperated shifting mechanism and a speed ratio responsive control device operatively associated concentric gear members connected by and meshing with planet gears, and a cage member journaled coaxially with said gear members and supporting said planet gears, said three members being connected respectively to said three shafts so thatithe torque delivered to the two pumps is maintained in balance.

CHARLES MARTIN OLEARY.

REFERENCES CITED Number 18 UNITED STATES PATENTS Name Date Burnam July 12, 1919 Wright et al. July 9, 1912 Alden May 27, 1913 Klein Sept. 21, 1915 Duke et a1 Apr". 11, 1916 Sheldon Jan; 7, 1936 Turney May 30, 1939 Archer May 12, 1942 Pollard Nov. 24, 1942 Gisching Dec, 28, 1943 Buchart May 30, 1944 Brunken Apr. 10. 1945

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