US3023706A - Gear pump and relief valve - Google Patents

Description

March 6, 1962 A. DE FEZZY EI'AL 3,023,706

GEAR PUMP AND RELIEF VALVE Filed March 24, 1960 2 Sheets-Sheet 1 INVENTORS TTORNEY March 6, 1962 Filed March 24, 1960 A. DE FEZZY EI'AL GEAR PUMP AND RELIEF VALVE 2 Sheets-Sheet 2 INVENTORS ATTORNEY United States Patent 3,023,706 GEAR PUMP AND RELIEF VALVE Albert De Fezzy and James 0. McVicar, Detroit, Mich, assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Mar. 24, 1960, Ser. No. 17,398 3 Claims. (Cl. 103-42) This invention relates to a pump and more particularly to a gear-type pump for hydraulic fluids.

The invention contemplates a gear pump of relatively compact and inexpensive construction having an improved passage and gear mounting arrangement and an integral relief valve permitting the pump housing members to be precision cast as by die casting and used with a minimum of machining. In certain of its more specific aspects, the invention further contemplates a gear pump particularly adapted for use as a fuel circulating pump and capable of integration into a combined accessory drive mechanism including a positive displacement blower such as shown and described in copending United States patent application Serial No. 2,057, filed January 12, 1960, in the names of William R. Fox and Harvey G. Humphries and entitled Combined Engine Accessory Drive and Housing Therefor.

The foregoing and other objects, advantages and features of the invention will be apparent from the following description of a preferred illustrative embodiment, reference being made therein to the accompanying drawings, in which:

FIGURE 1 shows a gear-type fuel pump which is constructed in accordance with the invention and mounted on and driven through a positive displacement blower, with portions of the gear pump and blower being broken away to show certain details of the pump construction and drive in longitudinal section;

FIGURE 2 is a fragmentary sectional view of the gear pump taken in the direction of the arrows and substantially in the plane of the line indicated at 22 of FIG- URE 1;

FIGURE 3 is a sectional view taken in the direction of the arrows and substantially in the plane of the line indicated at 33 of FIGURE 1;

FIGURE 4 is a sectional view taken in the direction of the arrows and substantially in the plane of the line indicated at 4-4 of FlGURE l; and

FIGURE 5 is a sectional view taken in the direction of the arrows and substantially in the plane of the line indi cated at 5--5 of FIGURE 1.

Referring more particularly to the drawings, a fuel pump constructed in accordance with the invention is indicated generally at 20. in the illustrative embodiment, the pump 24} is supported by and driven through a positive displacement blower, the housing of which is indicated by the reference numeral 11. The blower housing includes an end plate member 12 which defines one end of the blower pumping chamber. The end plate 12 is secured between a cover member 13 and a second blower chamber defining member 14. An oil receiving drive housing compartment 15 is defined between the end plate 12 and the cover member 13. A hearing 16 is carried by the end plate 12 and rotatably supports "a journal shaft 17 which is carried by the impeller 18 and projects into the compartment 15. The blower end plate cover 13 is provided with a pump mounting bore or opening 19 which extends therethrough in substantial axial alignment with the impeller journal shaft 17.

The housing of the pump 20 comprises a pump body member 21 and a cover member 22. These housing members are secured together by suitable screws or bolts 23 and 23' and define a pumping chamber 24 there- 3,023,706 Patented Mar. 6, 1962 ice between. The pumping chamber 24 is partially formed by two overlapping gear mounting counterbores 24' and Z in the body member 21. These gear mounting counterbores are overlapped =by inlet and outlet chamber defining counterbores 37' and 38'. The end of the valve body member opposite the pumping chamber is provided with a pilot boss 25 and a mounting flange 26. The pilot boss 25 is telescopically embraced by the opening 19 in the blower end plate cover member 13, the flange 26 mating with and being secured by bolts 27 to a mounting face 19' provided on the cover member 13 adjacent the openin g 19.

A bore 28 extends through the valve body member 21 and journals a shaft 29 in axial alignment with the impeller shaft 217. A counterbore 30 is concentric of the bore 28 and spacedly embraces the portion of the shaft 29 adjacent the drive housing compartment 15. Two seals 31a and 31b are spacedly mounted in the counterbore 30 and rotatively seal the drive end of the shaft. An impeller gear 32 is secured by a ball key 33 to the opposite end of the shaft 29 within the counterbore 24. The impeller gear 32 'drivingly meshes with a driven impeller gear 34. The driven gear 34 is journaled on the projecting end of a stationary sleeve shaft 35 which is mounted in a bore 36 formed in the valve body in spaced parallel relation to the bore 28 and the drive shaft 29.

The cover member 22 is provided with inlet and outlet ports or passages 37 and 38 which are connected to the inlet and outlet chambers 37 and 38, respectively, of the pumping chamber 24 on opposite sides of the meshing engagement between the impeller gears 32 and 34. Depending upon the installation requirements, these inlet and outlet passages may extend straight through the cover member as the inlet passage 37 shown or may be angled as the shown outlet passage 38. The cover member 22 also has a bore and counterbore at 39 and 40, respectively, which are in axial alignment with the sleeve shaft 35 and its mounting bore 36. The stepped diameters of the bore 39 and the counterbore 40 provide a conical valve seating shoulder 41 extending therebetween. A poppet valve member 42 is mounted in and spacedly embraced by the chamber defined by the counterbore 40, the sleeve shaft 35 and the closed end of the sleeve shaft mounting bore 36. A spring 43 is compressively interposed between the end of the bore 36 and the head of the valve 42 and tends to bias the valve member into sealing engagement with the valve seat 41. The bore 39 is connected by an obliquely extending passage 44 to the pressure discharge outlet passage 38 of the cover member 22. This connection subjects the closed head of the valve 42 to the discharge pressure of the pump. The counterbore 4t behind the poppet valve and seating shoulder is connected to the fuel inlet chamber 37 by a groove 45 opening on the pump chamber face of the cover member between the counterbore and the inlet passage 37. The poppet valve 42 thus serves as a pressure relief or regulating by-pass valve interconnecting the pressure outlet of the pump with the fuel inlet chamber 37 when the pressure in the outlet passage 38 has reached a desired operating level as determined by the preselected compressive loading of the valve spring 43.

To prevent the build-up of fluid pressure on the shaft seal 31a, a drain passage 46 interconnects the space intermediate this seal and the closed end of the seal mounting counterbore 30 to the inlet or suction side of the pump through the by-pass valve mounting chamber and the bypass groove 45 in the cover plate. Two drain ports 31d and 31e intersect the valve body member intermediate the seals 31a and 31b. Depending upon accessibility and the mounted position of the pump unit, one of these ports may be plugged. At least one of these ports, however,

and preferably the lower port may be connected to a suitable drain pipe, not shown. This seal and drain passage arrangement insures against leakage of fuel oil past the seal 31b and into the drive compartment 15 which would result in contamination of the engine lubricating oil. Any substantial flow of fuel through drain ports 31d or 31e and piping connected thereto signals the failure of the seal 31a. Similarly, any substantial flow of lubricating oil through these drain ports and piping signals any failure of the seal 31a.

The end of the shaft 29 projecting from the seal 31b is provided with a square spline at 48. This spline provides a driving connection with the mating hub of a yolk member 49 of a universal drive connection 50 intermediate the fuel pump and the adjacent impeller journal shaft 17. The arms of the yolked member drivingly engage radially extending slots 51 which are formed in a drive disc or plate 52. The disc 52 is also provided with a plurality of stamped bosses 53 which are drivingly engaged by cooperating slots 54' formed in the adjacent end of a drive sleeve member 54. The sleeve member 54 is in turn drivingly splined to the impeller shaft 17 and is retained thereon by the disc 52 and a bolt 55 which passes therethrough and threadably engages the end of the shaft 17. The drive connection 50 is thus adapted to accommodate limited lateral and angular misalignments occurring between the impeller shaft 17 and the pump drive shaft 29 as a result of manufacturing and assembly tolerances.

From the foregoing, it will be seen that the invention accomplishes the several objects and advantages stated above and provides a relatively simple, compact by-pass valve arrangement in the space normally occupied by the journalling of the driven impeller gear. This by-pass valve arrangement simplifies the fluid passages necessary in pump housing components and permits precision casting and use ofsuch housing components with a minimum of cost increasing machining.

While the invention has been described with reference to a single illustrative embodiment, it will be appreciated that various changes and modifications might be made therefrom without departing from the spirit and scope of the invention, as defined in the following claims.

We claim:

1. A gear pump comprising a first body member having a first bore extending therethrough, a second bore therein extending in spaced parallel relation to said first bore and being closed at one end thereof, an end face opposite the closed end of said second bore and normal to the axes of said bores, two overlapping counterbores coaxial with said first and second bores and opening to said end face and defining the peripheral ends and one side of a pumping chamber, and having two shallow bores intersecting both of said counterbores on opposite sides thereof to define fluid inlet and outlet chambers; a second body member secured to said first body member and having an end face in mating relation with the end face of said first body member and closing said pumping chamber, said second body member having the first passage means therein for supplying fluid to said inlet chamber, a second passage means therein for discharging pressurized fluid from said discharge chamber, a bore and counterbore in alignment with the second bore of said first body member and defining an annular 'valve seating shoulder, a third passage means therein connecting the bore of said second body member with the discharge passage means therein, and a fluid passage defining groove therein opening to the pump chamber face thereof and extending between said first passage means and the counterbore of said second body member; a pump driving shaft rotatably mounted in the first bore of said first body member and projecting into said pumping chamber; an impeller gear drivingly secured to said driving shaft within said pumping chamber and having rotative fluid sealing clearances with the adjacent pump chamber defining surfaces; a sleeve telescopically and *non-rotatably mounted in the second bore ofsaid first body member, said sleeve projecting into said pumping chamber and cooperating with the counterbore of said second body member to define a valve mounting chamber; a second impeller gear journaled on the projecting end of said sleeve and having rotative sealing clearances with the adjacent pump chamber defining surfaces and fluid pumping gear tooth interengagement with said first impeller gear; a valve member mounted in said valve chamber and matable with said valve seating shoulder; and a valve spring compressively interposed between said valve member and the closed end of the second bore of said first body member, said spring being prestressed and of suflicient rate to maintain said valve member in seating engagement with the annular valve seat when the pump dis charge pressure applied thereto through the discharge connected bore of the second body member is below a desired pressure level, said valve member being shiftable out of fluid sealing engagement when the fluid pressure applied thereto is above said desired level thereby providing fluid pressure venting communication between said inlet and discharge chambers.

2. A gear pump including a first body member comprising a pump housing portion at one end thereof, a hollow cylindrical flange portion extending from said housing portion and a mounting flange portion extending transversely of the cylindrical flange portion at the end thereof remote of said housing portion, said pump housing portion having a first bore extending therethrough in axial alignment with said cylindrical flange, a second bore therein extending in spaced parallel relation to said first bore and being closed at one end thereof, a passage connecting the closed end of said second bore to the interior of said cylindrical flange portion, an end face opposite the closed end of said second bore and normal to the axes of said bores, two overlapping counterbores coaxial with said first and second bores and opening to said end face and defining the peripheral ends and one side of a pumping chamber, and having two shallow bores intersecting both of said counterbores on opposite sides thereof to define fluid inlet and outlet chambers; a second body member secured to said first body member in mating relation with said end face and closing said pumping chamber, said second body member having a first passage therein mating with and connectable to supply fluid to said inlet chamber, a second passage therein mating with and connectable to discharge pressurized fluid from said discharge chamber, a bore and counterbore in alignment with the second bore of said first body member and defining a frusto'conical annular valve seating shoulder, a third passage means therein connecting the bore of said second body member with the discharge passage means therein, and having a groove therein opening to the pump chamber face thereof and extending to define a fluid passage between said first passage means and the counterbore of said second body member; a pump driving shaft journaled within the first bore of said first body member and projecting therefrom into said pumping chamber and axially of said flange portions; fluid sealing means interposed between said cylindrical flange portion and said shaft, in spaced relation to said housing portion, an impeller gear drivingly secured to said driving shaft within said pumping chamber and having rotative fluid sealing clearances with the adjacent pump chamber defining surfaces; a sleeve shaft telescopically and non-rotatably mounted in the second bore of said first body member in spaced relation to the closed end thereof, said sleeve shaft projecting into said pumping chamber and cooperating with the counterbore of said second body member to define a valve mounting chamber; a second impeller gear journaled on the projecting end of said sleeve shaft and having rotative sealing clearances with the adjacent pump chamber defining surfaces and fluid pumping gear tooth inter-engagement with said first impeller gear; a poppet valve member reciprocably mounted in said valve chamber and comprising a tapered head matable with said valve seating shoulder and i l t i l l a stem extending longitudinally therefrom in spaced concentric relation to said valve mounting chamber, and a valve spring compressively interposed between said valve head and the closed end of the second bore of said first body member, said spring embracing said valve stem and being of a prestressed rate suflicient to maintain said valve head in fluid seating engagement with the annular valve seat when the pump discharge pressure applied thereto is below a desired pressure level, said valve member being shiftable out of fluid sealing engagement when the fluid pressure applied thereto is above said desired level thereby providing fluid communication between said inlet and discharge chambers.

3. A gear pump comprising two body members secured together and defining an oblate pumping chamber therebetween, one of said body members having a first bore extending therethrough from said pumping chamber, one of said body members having a second bore extending from said pumping chamber in spaced parallel relation to said first bore and being closed at its end opposite said pumping chamber and the other of said body members having a third bore and a counterbore therein defining an annular valve seating shoulder in alignment with said second bore, a sleeve telescopically and non-rotatably mounted in said second bore, said sleeve projecting into said pumping chamber and cooperating with the counterbore of said other member to define a valve mounting chamber, a first impeller gear journaled on said sleeve within said pumping chamber and having rotative fluid sealing clearances with the adjacent pump chamber defining surfaces, a pump driving shaft rotatably mounted in said first bore and projecting into said pumping chamber, a second impeller gear drivingly secured to said driving shaft within said pumping chamber and having rotative sealing clearances with the adjacent pump chamber defining surfaces and fluid pumping gear tooth engagement with said first impeller gear, said gear tooth interengagement cooperating with and dividing the intermediate portions of said oblate pumping chamber to define a fluid inlet chamber and a fluid outlet chamber on opposite sides thereof, a first passage means defined by one of said body members and connectable to supply fluid to said inlet chamber, a second passage means defined by one of said body members and connectable to discharge pressurized fluid from said outlet chamber, a third passage means defined by said other body member and connecting said third bore with said outlet chamber, a fourth passage means defined by one of said body members and connecting said valve mounting chamber to said inlet chamber, a valve member mounted in said valve chamber and having a head thereon shiftable into fluid sealing engagement with said valve seating shoulder, and a valve spring compressively interposed between said valve head and the closed end of said second bore to maintain said valve head in fluid sealing engagement with the annular valve seating shoulder when the pump discharge pressure applied thereto through the third passage means is below a desired pressure level and said valve member being shiftable out of fluid sealing engagement when the fluid pressure applied thereto is above said desired level thereby venting the pumped fluid to said inlet chamber through said valve mounting chamber and said fourth passage means.

References Cited in the file of this patent UNITED STATES PATENTS 2,149,969 Lattner Mar. 7, 1939 2,505,191 Lauck Apr, 25, 1950 2,771,844 Lipinski Nov. 27, 1956

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