US2948228A

US2948228A - Gear arrangement functioning as pump or motor

Info

Publication number: US2948228A
Application number: US578836A
Authority: US
Inventors: Ahlen Karl Gustav
Original assignee: Svenska Rotor Maskiner AB
Current assignee: Svenska Rotor Maskiner AB
Priority date: 1956-04-17
Filing date: 1956-04-17
Publication date: 1960-08-09
Anticipated expiration: 1977-08-09

Description

' Aug. 9, 1960 2,948,228

GEAR ARRANGEMENT FUNCTIONING AS PUMP OR MOTOR K. AHLEN 6 Sheets-Sheet 1 Filed April 17, 1956 GEAR ARRANGEMENT FUNCTIONING AS PUMP 0R MOTOR Fired April 17, 1956 K. G. AHLEN Aug. 9, 1960 6 Sheets-Sheet 2 K. G. AHLEN Aug. 9, 1960 GEAR ARRANGEMENT FUNCTIONING AS PUMP 0R MOTOR Filed April 17, 1956 6 Sheets-Sheet 3 Aug. 9, 1960 K. e. AHLEN GEAR ARRANGEMENT FUNCTIQNING AS PUMP OR MOTOR Filed April 17, 1956 6 Sheets-Sheet 4 Aug. 9, 1960 K. G. AHLEN ANGEMENT FUNCTIONING AS PUMP 0R MOTOR GEAR ARR Filed April 17, 1956 6 Sheets-Sheet 5 Aug. 9, 1960 A LE 2,948,228

GEAR ARRANGEMENT FUNCTIONING AS PUMP OR MOTOR Filed April 17, 1956 6 Sheets-Sheet 6 sible whereas the inner surface 44 of the other casing 46 surrounding the follower gear 22 is generated in the following manner.

Referring to Fig. 4, 48 constitutes the center of the adjustment shaft 32 and the rotation center 50 of the follower gear 22, which is movable along an arc with the radius r from one extreme limiting position 50, in which the gears are in maximum mesh giving maximum capacity, to a second extreme limiting position 50' in which the gears are in minimum mesh giving minimum capacity. Accordingly the adjustment shaft 32 will revolve about its center 48 within the angle of radii 4852 and 4852, and theenveloping surface 44 comprises three cylindrical areas 54-52, 5252' and 5256. The first cylindrical area 54-52 has a radius slightly greater than the radius R of said follower gear and a center of curvature coinciding with the center 50 of the follower gear 22 when in its extreme limiting position for maximum mesh. The portion S I-52 extending from the high pressure port has a length corresponding to at least the space width between two teeth of the follower gear. The second cylindrical area 52-52 has a radius equal to the sum of the radius R of the follower gear, the width r of the eccentricity of the bearing surface in re1ation to the adjustment shaft and the necessary clearance between the gear and the surface. The portion 52'52' has its center of curvature coinciding with the center 48 of the adjustment shaft 32. The portions 5452 and 52-'52' merge into each other at the point -2 lying in the radial plane from the center 48 of the adjustment shaft through the center 50 of the follower gear in its extreme limiting position for maximum mesh. The cylindrical area 52'56 has a radius slightly greater than the radius R of the follower gear and a center of curvature coinciding with the center 50' of the follower gear 22 when in its extreme limiting position for minimum mesh. The portions 52 52' and 52'56 merge into each other at the point 52' lying in the radial plane from the center 48 of the adjustment shaft through the center 50' of the follower gear in its extreme limiting position for mesh. Figs. 2 and 3 show the follower gear 22 contacting the first and third cylindrical area portions of the enveloping surface 44 respectively.

By varying the mesh variable volumetric capacity is effected with constant r.p.m. Rotation of the adjustment shaft 32 can be accomplished by means of a lever 58 and adjustments can be made by the application of positive force or by self adjustment against a spring 60. Through a resilient actuation of the adjustment shaft a constant pressure is created after the pump, when it is possible to vary its capacity by applying various degrees of tension to the spring. The constant pressure is maintained in the area which is covered by the variation that is possible between the two limit stops. The pump maintains a cer-' tain pressure irrespective of the resistance in a certain area for the quantity variations allowed by the pump. The same variation can be achieved also by manual or comparable adjustment of the shaft when the pressure can be made to vary depending on the ability of the re ceiving collector tank to absorb fluid quantity at a certain pressure.

In the arrangement according to Fig. 1 it is possible to use the lever 58 for the adjustment of the follower gear within two stops limited by stop devices 62 and the resilient arrangement 60 for taking up the torque by means of tooth profile is equal with the rear end of the preceding tooth profile. Due to the helical gears an improvement ,4 is made by the fact that the teeth of the two gears always are in effective mesh with each other.

In Fig. 2 the direction of the gear rotation has been marked with arrows, just like the direction of the liquid flow when the arrangement is used as a pump. When used as a motor the flow direction of the medium is reversed. The same remark applies to the other illustrated designs. With an arrangement according to the design used as a motor constant torque is obtained within a certain rpm. range.

In the arrangement according to Figs: 510 the drive gear 64 is of internal tooth type with unpierced tooth bases 66 and encased in the cavity created by the casing composed .of the

halves

70, 72. The gear race of the drive gear 64 may be designed in one piece with a supporting part 74, to which the axle shaft'76 of drive gear 64 is connected, which axle shaft is supported in casing half 70. The follower gear 78 eccentrically supported is located inside the drive gear and its adjustment shaft 80 with eccentric bearing surface 82 for the follower gear is supported in casing half 72, where 84 indicates a bearing bushing. The adjustment shaft 80 is provided with an external lever 86 operating between the

stops

88, 88 and the rotation of the adjustment shaft towards the extreme limit stop corresponding to stop 88 occurs against the actuation of a spring 90.

To the adjustment shaft 80 a circular disc 92, concentric with said shaft, is attached which is supported in the casing half 72, i.e. on the opposite side of the gear elements in relation to the supporting part 74 for the external gear element 64. This disc 92 has on the high pressure side of the arrangement a sealing strip 94 projecting axially down into the intermediate space which contacts the tooth addendum circle of the internal gear 78. A stationary sealing strip 96 is attached to the casing half 72 and located in said intermediate space. The latter sealing strip 96 contacts externally the tooth addendum circle of the drive gear 64 and internally the outer edge of the sealing strip 94 contacting the follower gear 78, when the sliding plane 98 between these two sealing strip-s is located along a circle concentric to the adjustment shaft 80, the diameter of which is equal to that of the disc 92.

The internal sealing strip 94 accordingly follows the adjustment shaft 80 when it is adjusted rotationally and slides along the sealing surface 98 against the external the sealing strips is provided with a packing 100 facing the joint between the sealing strips.

The disc 92 on the adjustment shaft ,80 is provided with

curved flow holes

102, 104 for the axial inlet and

outlet

106, 108 of the operating medium of the pump (the designations inlet and outlet change place when the arrangement is used as a motor). At the rear of the supporting part 74 for the external gear race 64 a cavity 110 is located axially behind the flow hole 104 on the pressure side of the arrangement and connected by means of

ducts

112, 114, 116 with this flow hole in order to equalize the surface pressures (Figs. 7-8). In this as well as in all other designs according to the lnvention the pressure component of the hydraulic pressure on the pressure side, actuating the driven gear or the driven gear and the sealing strip, should always pass through the distortion center of the eccentric shaft on the side that provides a torque disengaging the gears. The bearing pressure resulting from the driven gear should always tend to rotate the eccentric shaft in such a Way that the mesh of the gears will decrease when the arrangement is operating as a pump and the reverse when the arrangement is operating as a motor.

The arrangement shown in Figs. 11-12 is principally of similar design as that described above in connection with Figs. -10 differing from said arrangement only by the fact that the tooth bases of the external gear element 118 arepierc'ed so that radial inet and outlet'holes '120are ereated forthe operating medium. For this reason the 122 of the arrangement should be provided with at leastin principle radial inlets 124 and outlets 126 for the operating medium Otherwise the details correspondin withthe partsof Figs. 5-10 are designated with the same reference characters and inorder toavoid repetition any further description of-the same is not necessary. The aiil'e'shaft of the drive gear 118 ,is supported by means of needle bearings 128 in a bushing 130 arranged on the corres onding end of the casing 122. A pressure medium actuated operating mechanism 132 is provided for the mechanical operation of the lever 86 against the actuation of the spring 90.

- Figs. '13 and 1-4- show the gear profiles of external and internal gear type with cut down tooth addendurns "134 and 135, respectively, with the exception in this instance of the end parts 138 and 140, respectively, of the tooth addendurns, which function as mesh guides for the corotation of the gears. At least one of the gears in each one of-the'arrangements describedabove can be provided with such a design due to which the arrangement has to be made larger in order to obtain desired capacity, but by means of which an increasing degree of variation is obtained with regard to the capacity of the arrangement, etc. In order to be able to get down to zero in regard to circulating quantity such an outlet is to be used.

In the diagram of Fig. 15 the pressure rise is shown as the function of the r.p.m. (n) of the pump when the curve 1 constitutes the volumetric efficiency of the pump. The regulating range of the pump is indicated by means of a thick line, provided it works with a spring only for self-adjustment of the adjustment shaft against the eifect of the liquid pressure in the pump discharge. By adding a servomotor, for example an electrically operated solenoid, hydraulically or pneumatically operated pressure plunger or similar power source, it is possible to apply a torque to the adjustment shaft. The size and direction of this torque maybe optionally adjustable,

whereby the various pressure regulating range curves are obtained, which are included in the diagram shown in 6) a a ement app dca a 11 t discha ge may be connected either behind the pressure plunger 150 via line 148 .or inf-rout of the pressure plunger 150 via the line 148', when the change-over is made via, athree way valve 152. This means that in the diagram shown in Fig. 15 the curve scales ascend and descend, respecitive ly, in' relation to the base line for remote control only, A presspr'e variator 154 can be installed in the supply line to the pressure plunger 150 and for operating medium in the pressure plunger a separate medium in relation to the pump operating medium may possibly be used. 'Theservo motor maybe designed to be actuated from a distance by means for variation of thepressure in the supply line tot-he pressure plunger. Fig. 18 shows a controlsystem for a motor cox-rec sponding to the system in Fig. 17 for a pump. The spring 146' tends to separate the gems from each other, whereas the motor inlet by means of a line 148' is connected with the pressure plunger in such a manner that on rising pressure the gears assume-a more close fit. v

The control system in Fig. 19 for anarrangement ac cording-to the invention operating as-a pump is provided with a servo motor in theform of asolenoid, the armature 156 of which is actuated by the coil 158. The coil 158 is fed from the circuit '160 and by means of a cur rent changer it is possible to alternate the direction of the current and further control the amperage by means of a regulating resistor 164 for the purpose of moving the regulating range of the pump according to the principles as shown in Fig. 15.

What I claim is:

1. A rotary unit having a casing providing a chamber, a drive gear and a follower gear disposed in said chamher, said gears intermeshing with each other, an adjusting shaft angularly adjustably mounted in said casing in spaced relationship to the axis of said drive gear, said adjusting shaft being provided with a cylindrical :bearing surface eccentric to the axis of said adjusting shaft, said Fig. 15. Accordingly 'above the curve for the spring alone are curves where the servo motor torque is added to the spring and below said curve characteristics in which the servo motor counterbalances the spring eflect. The servo motor power and the spring powermay be located either partially with each other as in Fig. 11. or located in series, whereby various types of characteristics are obtained.

In the regulating system according to Fig. 16 the arrangement is shown functioning as a pump by means of full-drawn lines. The lever 142 for adjustment of the adjustment shaft 144 for the eccentric bearing surface is retained by a spring 146 so that the gears are in maximum mesh. The pump discharge is connected with a pressure plunger 150 by means of a line 148. At rising pressure in the discharge the gears are accordingly separated from each other.

Thus it is possible to adjust the pump irrespective of the r.p.m. or r.p.m. variations and resistance variations within a certain range in order to provide constant pressure and the possibility of obtaining optional pressure. Principally constant pressure is obtained in certain areas and it is possible to select the pressure range from outside without having to by-pass any liquid quantity.

When the same arrangement is used as a motor, which is indicated by dash lines, the spring 146 works instead to separate the gears from each other, whereas the inlet of the motor is'connected with the pressure plunger 150 via the line 148' in such a manner that the pressure plunger 150 tend to increase the mesh between the gears.

In the control system according to Fig. 17 with the bearing surface supporting said follower gear for adjustment of the inter-mesh between said gears by angula-r adjustment of the adjustment shaft, from one extreme limiting position in which the gears are in maximum mesh giving maximum capacity to a secondextreme limiting position in which the gears are moved apart and are in minimum mesh giving capacity, said chamber having a cylindrical surface in seal-ing relation with the outer periphery of the teeth of the drive gear and a non-adjustable enveloping surface in sealing relation with the outer periphery of the teeth of the follower gear, said oasing having opposed radial high pres sure and low pressure ports communicating with said chamber between said cylindrical surface and said enveloping surface with said surfaces terminating at said ports, said enveloping surface comprising one portion constituting a cylindrical area having a radius slightly greater than the radius of said follower gear and extending from said high pressure port, saidportion having a center of curvature coinciding with the center of the follower gear when in its extreme limiting position for maximum mesh and having a length corresponding to at least the space width between two teeth of the follower gear, 'a' second portion constituting a cylindrical area having a radius equal to the sum of the radius of the follower gear, the width of the eccentricity of the bearing surfacein relation to the center of the adjusting shaft and the necessary clearance between the follower gear and the surface and with a center of curvature coinciding with the center of said adjusting shaft, said second portion merging into said first portion along a line lying in the radial plane from the center of said'adjusting shaft through the center of said follower gear in the extreme limiting position for maximum mesh, and a third portion constituting a cylindrical area having a radius slightly greater than the radius of said follower gear and with a center of curvature coinciding with the center of said follower gear when in extreme limiting position for minimum mesh, said third portion terminating at said low pressure port and merging into said secend portion along a line lying in the radial plane from the center-of said-adjusting shaft through the center of said follower gear when in extreme limiting position for minimum mesh.

2. A rotary unit as defined in claim 1, provided with a radially projecting handle for rotating the adjusting shaft.

3. A rotary unit as defined in claim 1, acting as a pump, which includes resilient means for automatic adjustment of the adjusting shaft against the action of the liquid pressure in the pump discharge.

4. A rotary unit as defined in claim 1 in which the gears are of the external tooth type and are located sidehy-side.

' 5. A rotary unit as defined in claim 1 in which the gears are of the involute type.

6. A rotary unit as defined in claim 1 in which it includes gears of helical shape.

7. A rotary unit as defined in claim 6 in which a. front end of a gear tooth profile is located in one and the same radial plane as the rear end of the preceding gear tooth profile.

References Cited in the file of this patent v UNITED STATES PATENTS" Auger. Aug. 3-, 1920 Bechler Oct. 12, 1926 Mohl Oct. '19, 1926 Brenzinger Oct. 26, 1926 Wilsey 3. Feb. 28, 1928. Frey Nov. 13 19'28' Grant Mar. 12, 1929 Lawser Feb. 14, 1933 Gamer Oct. 3, 1933 Wendell Nov. 26, 1935 Blwert July 21, 1936 Ungar Dec. 28, 1943 Heckent July 29, 1947 Grosser Dec. 28, 1948 Clarke Dec. 6, 1949 Topanel-ian May 30, 1950. 'Rorive Apr. 17, 1951 Pontius June 17, 1952 Johnson Dec. 23, 1952 Ung-ar Oct. 12, 1954 Joy July 17, 1956