US2383153A

US2383153A - Sealing device for internal gear pumps

Info

Publication number: US2383153A
Application number: US505304A
Authority: US
Inventors: John B Parsons
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-10-07
Filing date: 1943-10-07
Publication date: 1945-08-21
Anticipated expiration: 1962-08-21

Description

Aug. `21, 1945. J. B. PARSONS SEALING DEVICE FOR INTERNAL GEAR PUMPS Filed Opt. 7, 1943 @www SP1/UW dhnfjxrwnd, @M M f) Patented Aug. 21, 19475 SEALING DEVICE FOR INTERNAL GEAR PUMPS l John B. Parsons, Toledo, Ohio Application October 7, 1943, Serial No. 505,304

1 Claim.

This invention relates to internal gear pumps but more particularly to the sealing of the ends of such pumps.

It is necessary that opposite ends of internal gear pumps be satisfactorily sealed in order to militate against the loss or dissipation of pressure tain an effective seal. This is laborious and costly,

thereby substantially increasing the cost of the assembly.

An object is to overcome the above dilculties and to produce a new and improved seal which is entirely automatic in operation, and reliable under all conditions, liquid or fluid pressure generated by the pump being employed for this purpose, thereby substantially reducing the cost of manufacture and assembly.

For purposes of illustration but not of limitation, an embodiment of the invention is shown on the accompanying drawing in which p Figure 1 is a side elevation with parts broken away, of an electric motor driven internal gear pumping unit;

Figure 2 is a transverse sectional view on the line 2--2 of Figure 1;

Figure 3 is a plan View of the ported plate which abuts against one end of the internal gear pump;

Figure 4 is a plan view of a plate which abuts against the lower end of the internal gear pump; and l Figure 5 is a spring washer or spacer for normally holding the pump and plate parts in position.

The illustrated embodiment of the invention comprises a pumping unit having a central block I on the upper side of which is suitably mounted an electric motor II and attached to the under side of the block Il) is a cup I2 which serves as a liquid reservoir. The cup I2 is held in position by a bail pivotally mounted in any suitable manner on the block I0. The electric motor II has an armature shaft I4 which projects downwardly into a pump housing I5 the lower end of which is open. A closure cap I6 is secured to the lower end of the pump housing I and is secured in place by screws Il. A packing ring I8 in the pumping housing prevents the escape of liquid along the closure cap I6.

A tube I8 depends into the reservoir I2 and terminates near the lower end thereof, liquid being pumped through this tube to atransverse passage I9 which terminates in the downwardly extending port 20 opening into the pump housing I5. In this manner it will be seen that the tube I8, passage I9 and port 20 provide the inlet to the pump housing I5. Liquid is forced from the pump housing I5 through an upwardly extending port 2I to a transverse passage 22 and thence laterally through a passage 23 to a suitable outlet nipple (not shown). A spring tensioned valve 24 is slidable in the transverse passage 23. In the event the pressure exceeds a predetermined maximum, the valve 24 will be retracted sufficiently to enable the liquid to return to the reservoir I2 through a passage 25 which communicates with a vertical tube 2l similar to the tube I8. A port 26 enables liquid to be returned to the reservoir which may be in rear of the valve 2l. Reference is hereby made to my co-pending application Serial No. 452,865, entitled Motor pump unit, for more detail Idescription of the above described structure.

Arranged within the pump housing I5 is an internal gear pump P which may be of any suitable or desired construction. In this instance, the pump P has an outer rotor 28 formed with five notches .29, the side walls of which are flaring along curvilinear surfaces 30. The inner rotor 3| is formed with four teeth, lthe side Walls of which are curvilinear .to correspond approximately with the curvilinear surfaces 3U of the outer rotor. The arrangement. is such that for each revolution of the inner rotor, the outer rotor is revolved four-iifths of a revolution. The construction and operation of the pump P is wellknown to those skilled in this art and since the same forms no part of the present invention, iur-ther detail description is not considered necessary. Such pump is the well-known structure commercially known as the Gerotor pump. It will be noted that -the toothed ro'tor 3| is fixed for rotation to the end portion of the armature shaft I4 by a key 32 but is free for axial movement along the shaft. Upon energizing the electric motor II, the internal gear pump P is operated to draw liquid from the reservoir I2 through the inlet passages above described and discharge the same under pressure through the outlet passages above described.

It will be manifest that in order for the pump to operate efficiently, leakage of iiuid must be prevented from the high pressure side of the pump to the low pressure side. It ls a desideratum that such seal be effected in a simple and inexpensive manner so that not only will an effective seal be established, but also that the wear on the parts so far as the seal is concerned, be substantially reduced or entirely eliminated. It will be understood that in the operation of the pump, both the gear parts 28 and 3| rotate so that the pump part 28 must have a nice fit within the nular groove 31 is formed on the housing on the upper side of and adjacent the periphery of the plate.

The pump housing I5 is of such size that a space is provided between the lower ends of the pump rotors 28 and 3l andthe closure cap I6. Arranged within this space and abutting against the lower ends of the pump rotors is a disclike plate 39, the peripheral portion of which engages the walls of the housing. The plate 39 is preferably of metal, is relatively thin and exible and is formed with a central aperture 40 which is substantially in alignment with the motor shaft I4. It will be manifest that the inner rotor 3| is slidable along the armature shaft I4 and the outer rotor 28 is likewise slidable in the housing. In order to sustain the weight of the rotors and the plate 39 and hold these parts in the desired position when the pump is at rest, a spring washer isarranged within the cavity or space 38 and is formed with` a plurality of radial spring arms 43 which bear against the under side of the plate 39. The washer 4I has a centrally arranged concave portion which bears against the central portion of the closure cap I6. It should be understood, however, that the spring pressure exerted by the washer 4I is not sufficient to establish the desired seal.

In operation, it Will be manifest that pressure uid passing Abetween the periphery of the disc 39 and the walls of the housing will ll the space 38 and impose an upward or axial pressure against the plate 39 and accordingly the pump rotors. The pressure imparted by the fluid in the vspace 38 will of course be dependent upon the pressure generated by the pump. It is desired that the plate 39 be relatively thin in order that it conform to the end surfaces of the rotors particularly in the event of any unevenness or irregularities in these surfaces so that the pressure exerted by the fluid, liquid in this case, may slightly deform the plate 39, thereby causing it to conform to the contour of these surfaces. The fluid pressure thus exerted will hold the plate 39 snugly and in` sealing contact with the pump rotors 28 and 3I and owing to the greater exposed area on the under side of the plate 39 as compared to the internal area of the pump p arts containing the pressure uid, the plate 39 is held in sufficiently tight contact to produce the desired sealing action, thereby militating against pump housing I5. At the upper end of the pump leakage of the pressure fluid from the high presboth sides of the plate. Otherwise inward deformation of the plate in this region would take place due to the high pressure imposed on the under side of the plate. In the event that the plate 39 were of greater thickness and rigidity, such an aperture would not be necessary, but where the plate 39 is of relatively thin material, such aperture is desirable.

As above mentioned, the annular groove 31 which is formed in the pump housing I5 above the ported plate 33 relieves a portion of the upward thrust or pressure which is created in the space or cavity 38. This vreduces the friction in that region and contributes to the efiiciency of the assembly. In this connection it will be apparent that pressure fluid finds its way between the pump and the ported plate 33 and enters the annular groove 31. In this manner a downward pressure on the upper side of the peripheral portion of the plate 33 is established sufficient to relieve a portion of the upward pressure created at the opposite end of the pump.

From the above description it will be apparent that I have provided an exceedingly simplebut effective seal foran internal gear pump whereby the high and low pressure sides of the pump are satisfactorily sealed from each other,`-` the seal being effected by the pressure generated by the pump. Thus the plates are forced against the ends of the pump with sufficient pressure to effect the seal but not to such an extent as to interfere with the proper operation of the pump or to effect excessive wear on the pump parts.

It is to be understood that numerous changes in details of construction, arrangement and operation may be effected without departing from the spirit of the invention especially as defined in the appended claim.

What I claim is:

Pump sealing means comprising in combination, a housing having a cylindrical cavity provided at one end with inlet and outlet passages, mating toothed pump rotor members arranged one within the otherl the outer rotor having an annular periphery providing a rotating t with `the walls of said cavity, shaft means projecting into one end of said housing and secured at its i inner end'portion to the inner of said rotor members for driving said rotors in eccentric relation to each other for creating expanding and contracting chambers thereby to force fluid under pressure from the inlet to the outlet passage, said rotor members being spaced slightly from the opposlte end of said cavity to provide 'a pressure space, a flexible plate of sheet material disposed in said pressure space and abutting against the adjacent surface of both' rotors, pressure uid being adapted to pass between said plate and rotors and about the edges of said plate to said pressure space said plate having an imperforate region covering such area of the rotors creating said expand-ing and contracting chambers, said plate being sufficiently thin to enable the fluid pressure withinv said pressure space to cause the same to effect a` sealing relation with the end faces of the rotors adjacent thereto, said plate being of such shape and dimensions relative to the side walls of said cavity as to maintain said region in position to cover said area, and meansl for normally holding said plate in abutment withy said pump rotor members.

JOI-IN B.'PARSONS.