JPS6340947B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pump of the type in which a pair of gear elements with meshing outer teeth are mounted within a housing.

In order to supply pressurized fuel to an engine, a pump is connected to a prime mover such as an engine that supplies fuel so as to drive one of the gear elements, and the other gear element is driven by this one drive gear. It is known to use.

The suction port of such a gear pump is supplied with fuel at a relatively low pressure by a pressure pump, and it is customary to maintain most of the inside of this gear pump housing at the discharge pressure of the pressure pump. . Leakage of fuel from the high pressure area to the pressurized area within the gear pump creates a static fluid bearing between the relatively movable parts of the gear pump. The drive gear is connected to a drive element that typically extends sealingly through the wall of the pump housing. During use, this drive element is axially loaded by the pressure of the pressure pump. Therefore, it is necessary to prevent the drive element from moving in the axial direction using a thrust bearing.

Furthermore, in modern fuel systems, the discharge pressure of the pressurizing pump is sufficiently high, resulting in unacceptably high axial loads being applied to the thrust bearing.

SUMMARY OF THE INVENTION An object of the present invention is to provide a gear pump in which the drive element is not subjected to strong axial loads resulting from increasing the discharge pressure of the pressure pump.

The gear pump of the present invention has a housing that constitutes a pump chamber, and a gear pump in which outer teeth mesh with each other within the pump chamber.
a pair of gear elements, the housing having an inlet and an outlet communicating with the pump chamber on opposite sides of the meshing zones of the gear elements; a drive shaft coupled to the gear element for axial movement, the drive shaft having an axially facing surface exposed to fluid pressure within the housing, the housing and one end of the gear element being connected to each other; and a sealing device between the housing and the other end of the one gear element, the sealing device separating the surface from the pressure in the pump chamber. do.

In the present invention, by providing a sealing device that isolates the surface of the drive shaft exposed to the fluid pressure in the housing from the pressure in the pump chamber, the drive shaft is prevented from receiving increased axial load during pump operation. It can be done.

In a preferred embodiment of the invention, the closed end of one gear element isolates the axially facing surface exposed to fluid pressure in the housing from the pressure in the pump chamber, so as to further increase the drop of said seal. Make it.

Other embodiments of the invention include an annular seal between one gear element and the drive shaft to isolate this splined area from the low pressure exhaust passage. A spring-loaded surface seal is also provided on the drive shaft, which separates the drive shaft through-hole for lubricating the splined area from the low-pressure discharge passage. do.

The invention will be explained with reference to the drawings.

The pump shown in FIG. 1 is of the prior known type disclosed in British Patent No. 1467441 and has a housing 10 provided with two parallel through holes 11,12. Two pairs of bearing blocks 13, 14 and 15, 16 are made slidable in through holes 11, 12. A gear element 17 is supported on blocks 13 and 15 and meshed with another gear element 18 supported on blocks 14 and 16. The teeth of the gear elements 17, 18 are rotatably arranged in a figure-8 pump chamber, and an inlet and an outlet communicating with the pump chamber are provided on opposite sides of the meshing zones of the gear elements 17, 18 in the housing. Provided for.

Gear elements 17, 18 are provided with axially passing holes which communicate with zones 20, 21 at the respective ends of the gear elements. The hole of the gear element 17 is made into a spline hole, and the transmission shaft 2 in the housing 10 is
One spline end of 2 is accommodated in this spline hole. The other end of the transmission shaft 22 is splined to the drive element 23. A drive element 23 passes through the wall of the housing 10 and a sealing device 24 is provided. This sealing device serves to prevent liquid from escaping from zone 21 through the housing wall. The axial end face of the drive element 23 in the housing 10 is located in the zone 21
subject to internal pressure. The thrust bearing 2 controls the axial movement of the drive element 23 in response to this pressure.
5. As previously mentioned, liquid from the pump outlet can leak into zones 20, 21, and the pressure in zone 21 is an increased pressure at the pump inlet, which increases the thrust bearing 24 to an unacceptable level. It can be high enough to apply high loads.

FIG. 2 shows a gear pump of the present invention, and unlike the conventional gear pump shown in FIG. 1, a single drive shaft 30 is provided in place of the transmission shaft 22 and the drive element 23. The drive shaft 30 is engaged with the spline hole 31 of the drive gear element 32. A closed end or barrier 33 separates the bore 31 from the exhaust passage 34 of the pump housing 35. Zone 3 by first spring loaded surface seal 36
Separate hole 31 from 7. This zone 37 corresponds to zone 21 in FIG. 1, and the suction pressure of the pump is applied to zone 37. This spring loaded surface seal 36 acts to isolate the axially facing face F of the drive shaft 30 from the suction pressure in the zone 37, which is a significant difference from the conventional pump shown in FIG. That is, in the conventional pump of FIG. 1, the suction pressure in the zone 21 acts on a wide surface of the drive element 23 in the zone 21, and a thrust bearing 25 is required.
In this embodiment of the invention, a second spring loaded surface seal 38 separates the exhaust passageway 34 from the zone 39. This band 39 corresponds to band 20 in FIG. Through the hole in the driven gear element 46 the zone 37,3
Connect 9.

In this specification, the pressure inside the pump chamber includes the pressure at the pump inlet, the pressure at the pump outlet, and the pressure between and around the two gears. The pressure level between and around the gears is intermediate between the pressure at the pump inlet and the pressure at the pump outlet, both of which are high pressures.
All of these pressures are fluid pressures within the housing, but in addition to the above-mentioned pressures within the pump chamber, there are drain fluid pressure and lubricating oil fluid pressure as pressures within the housing, both of which are low. Although the embodiment of FIG. 2 provides a separate supply of lubricating oil, a portion of the drain fluid may alternatively be utilized. In the present invention, the drive shaft 30 is provided with a surface F, which is an axially facing surface exposed to fluid pressure within the housing. Although plane F must be isolated from the pressure within the pump chamber in order for the drive shaft 30 to be free of axial forces, it need not be isolated from the fluid pressure within the rest of the housing.

An annular seal 45 is provided on the drive shaft 30, and this annular seal is engaged with the hole 31 to connect the hole to the first zone 40.
and a second band 41. The drain passage 34 is connected to the zone 41. An axial throughbore 42 in the drive shaft 30 connects the zone 40 to the outside of the pump housing. Preferably, lubricating oil is added to bore 42 to lubricate the spline engagement between shaft 30 and drive gear element 32. Annular seal 45 and barrier 33
Therefore, this lubricating oil cannot mix with the drain fuel in the passage 34. Lubricating oil is suitably added to the bearing 43 for the shaft 30 and is separated from the exhaust fuel in zone 41 by a third spring loaded surface seal 44 . Furthermore, the seal 44 serves as a sealing means between the shaft 30 and the housing 35.

Seal 36 separates shaft 30 from suction pressure in zone 37, and seal 44 and seal 45
The drain passage 34 is separated from the lubricating oil in the through hole 42 by this. In particular, the presence of the seal 45 allows lubricant to be added to the spline connection between the drive shaft 30 and the spline hole 31, yet prevents this lubricant from flowing directly into the discharge passage 34. A small amount of fluid flows through seal 36 to exhaust passage 34, as does a small amount of lubricating oil passing through seals 44,45.

In this way, the axial load caused by the very low pressure between the drain fuel pressure and the lubricating oil pressure is reduced to the drive shaft 30.
It's just a matter of receiving it. There is therefore no need for a thrust bearing for the shaft 30, no matter how high the pump inlet pressure level increases. band 3
The suction pressure of the pump 7 is applied to the area of the barrier 33,
The surface seal 36 prevents the gear element 32 from receiving an excessive load in the axial direction.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a conventional gear pump, and FIG. 2 is a longitudinal sectional view of the gear pump of the present invention. 11, 12...Through hole, 13, 14, 15, 16
...bearing block, 17, 18...gear element,
20, 21... End zone, 22... Transmission shaft, 23... Drive element, 24... Sealing device, 25... Thrust bearing, 30... Single drive shaft, 31... Spline hole,
32... Drive gear element, 33... Closed end or barrier, 34
...Discharge passage, 35...Pump housing, 36...Spring loaded surface seal, 37, 39, 40, 41...Zone, 38...Second spring loaded surface seal, 42...Through hole, 43...Bearing, 44...Third spring loaded Surface seal, 45... Annular seal, 46... Driven gear element.

Claims (1)

[Claims] 1. A housing 35 constituting a pump chamber, and a pair of gear elements 32, 46 whose outer teeth mesh in this pump chamber, and these gear elements 32, 46.
one of the gear elements 32 is provided with an inlet and an outlet in the housing, each communicating with the pump chamber on opposite sides of the meshing zones of the gear elements;
This gear element 3 can be moved in the axial direction relative to
2, the drive shaft 30 is provided with an axially facing surface F exposed to fluid pressure within the housing, and a seal between the housing 35 and one end of the one gear element 32; Device 3
6, and a sealing device 38 between the housing 35 and the other end of the one gear element 32, and these sealing devices 36, 38 isolate the surface F from the pressure inside the pump chamber. A gear pump featuring: 2. The gear pump according to claim 1, wherein the face F of the drive shaft 30 is separated from the pressure in the pump chamber by the closed end 33 of the one gear element 32. 3 splined connection of the drive shaft 30 to the one gear element 32 and an annular seal between the drive shaft 30 and the one gear element 32 for isolating the splined area from low pressure exhaust passages; 45 and a through hole 4 in said drive shaft 30 for supplying lubricating oil to said splined area.
2. The gear pump according to claim 1, wherein the drive shaft has a. 4. A gear pump according to claim 3, wherein the drive shaft 30 has a spring loaded surface seal 44 for isolating the through hole 42 from the low pressure discharge passage.