Pump-and-motor Unit, Particularly For Supplying Fuel

Abstract

A pump-and-motor unit comprises, within a sealed housing, a lateral channel pump and an electromotor, the rotor of which drives the impeller of the pump. The unit housing has at each end an axially aligned liquid inlet and outlet nipple, respectively. At the pressure side of the pump the liquid is guided from the lateral channel of the pump radially inwardly through a pressure channel provided in a lateral channel plate serving as a pump housing.

Description

This invention relates to a pump-and-motor unit which is particularly adapted for supplying fuel and which comprises a lateral channel pump and an electromotor. The liquid, as it flows through the unit, cools the armature assembly of the electromotor by contact and lubricates the bearings of the rotary components.

In pump-and-motor units of the aforenoted type it is of primary importance that the length and the diameter of the pump component be as small as possible. The degree of efficiency of these pumps is of lesser importance since delivery takes place under low pressure, the delivered quantities far exceed the quantities actually needed and the pressure is maintained substantially at a constant level by means of an overflow valve.

In a known pump-and-motor unit of the above type (such as disclosed in German Published Patent Application DOS 1,703,784) the suction and pressure conduits of the pump terminate axially in the lateral channel and are oriented in the same axial direction. In more recent designs it has been sought to attach the fuel inlet and outlet conduits at each axial end of the pump-and-motor unit. In this manner, as far as structure is concerned, the pump-and-motor unit has the outer appearance of an enlarged portion of the fuel line so that, for example, its orientation in mounting does not have to be changed. If one were to establish this type of fuel path in the known pump-and-motor unit, then a channel should be provided about the impeller externally thereof. Such a solution, however, would lead to an undesirable increase of the overall diameter of the pump-and-motor unit.

It is an object of the invention to provide an improved pump-and-motor unit of the aforenoted type in which the admission and withdrawal of fuel is effected at the two axial ends of the pump and in which the dimensions, particularly the diameter of the pump, is maintained at a small value, while consideration is given to the requirement that the high and low pressure sides of the pump have to communicate with one another through the aforenoted overflow valve.

Briefly stated, according to the invention, the removal of fuel through the unit is effected through a pressure channel from the lateral channel radially with respect to the rotary axis of the pump rotor.

The invention will be better understood, as well as further objects and advantages will become more apparent, from the ensuing detailed specification of a preferred, although exemplary, embodiment taken in conjunction with the drawing, wherein:

FIG. 1 is a longitudinal sectional view of a pump-and-motor unit taken along line I--I of FIG. 2 and

FIG. 2 is a sectional view of the pump-and-motor unit taken along line II--II of FIG. 1.

The pump-and-motor unit which is of compact structural design, comprises a liquid delivery pump 1 and an electromotor 2 which are enclosed in a two-part housing 3, 4. The liquid, such as fuel, flows in the direction of the axial arrows and first passes through the delivery pump 1. Thereafter the liquid flows longitudinally through the housing 3, 4 through the electromotor 2. In the housing portion 3, which comprises an inlet nipple 5, there is disposed a lateral channel plate 6 centered by means of a sealing ring 7 and rigidly connected with a fixed shaft 8. On the latter there is rotatably mounted a rotary assembly generally indicated at 9 which comprises the rotary components of the electromotor and an impeller 10 of the lateral channel pump. The rotary components of the electromotor 2 comprise, essentially, an armature formed of a winding 11 and of armature plates 12, a radial collector 13, bearings 14, as well as a casing 15 which is made of synthetic material and which encloses the armature. The casing 15 and the impeller 10 are made of the same material and are preferably manufactured as a one-piece component. The structural connection between the impeller 10 and the motor armature is effected by radially arranged webs 10a.

In the cylindrical housing portion 3 there is inserted a tubular housing 17 supported by the lateral channel plate 6. The housing 17 contains circumferentially spaced permanent magnets 18. The latter are axially offset with respect to the armature of the electromotor to cause the armature to be biased in the direction of the lateral channel plate 6. The bearing 14 provided in the zone of the impeller 10 thus serves not only as a radial bearing but also as a thrust bearing abutting the lateral channel plate 6. The clearance between the impeller 10 and the lateral channel plate 6 is determined by the length by which the bearing 14 projects axially beyond the casing 15 towards the plate 6. This clearance, through which the liquid may flow to the bearings 14 to lubricate the same, is thus maintained at a constant width during operation by virtue of the axially biased rotary assembly 9.

The housing portion 4 fits into the housing portion 3 in a plug-like manner and closes the same fluid tight by virtue of an inserted O-ring 19. In the housing portion 4 there are situated carbon brushes 20 which are urged against the radial collector 13 by springs 21. In addition, the housing portion 4 includes the outlet nipple 22. A support ring 23 fixedly held in the housing portion 4 serves as a further support for the shaft 8 in addition to the lateral channel plate 6.

As it may be observed in FIGS. 1 and 2, the liquid, such as fuel, is admitted through the inlet nipple 5 and an inlet opening 25 provided in the lateral channel plate 6 into the lateral channel 26. After flowing through the latter, the liquid is, at the pressure side of the pump 1, admitted through a pressure opening 27 arranged radially with respect to the axis of rotation to an annular groove 28 provided in the lateral channel plate 6. From the pressure opening 27 there extends, within the plate 6, an axial channel 29 which leads to the suction side of the pump-and-motor unit and is controlled by means of an overflow valve 30. The latter comprises a plate 31 which is tiltable about one end 32 which, in turn, is supported by a radial face of the lateral channel plate 6. The plate 31 has an orifice 33 through which passes the shaft 8. The plate 31 is loaded by a spring 34 which at its other end engages a ring 35. The latter frictionally engages the shaft 8, but is axially displaceable thereon for the purpose of varying the opening pressure of the valve 30.

In that portion of the lateral channel plate 6 which serves for separating the suction side 25 of the pump 1 from the pressure side 27 thereof and in that face of the plate 6 which is oriented towards the impeller 10, there is provided after the downstream end of the lateral channel 26 a cavity 37 which is at the same distance from the pump axis as the channel 29 and which leads through a radial channel 38 to the annular groove 28. In this manner, the pressure drop between the suction side 25 and the pressure side 27 is substantially reduced: the portion 39 of the lateral channel is discharged and thus a depressurization is effected. The portion 39 joins the lateral channel 26 and extends as a continuation of the lateral channel 26 with approximately the half width thereof and ends spaced from the cavity 37. In the extension 39 of the lateral channel 26 there prevails a certain overpressure of the liquid which has a rearward effect on the lateral channel 26 and counteracts the vaporization of the volatile liquid, such as fuel.

From the annular groove 28 of the lateral channel plate 6 the liquid is admitted into an annular groove 40 0f the rotary assembly 9. The groove 40 communicates with the motor chamber 42 through channels 41. It is thus seen that the liquid first flows radially inwardly in the lateral channel pump and is then guided axially and centrally into the motor chamber 42. This has the advantage that the diameter of the impeller 10 may be increased causing a higher peripheral speed of the liquid in the lateral channel 26. This results in a better pressure head at lower rpm's and thus in a greater life expectancy of the pump.

The webs 10a bound the channels 41 between the impeller 10 and the casing 15 and operate as a centrifugal pump aiding the flow of liquid. In this manner the lateral channel pump 1 is relieved at the pressure side. This relief, however, is maintained at such a low level that on the pressure side of the lateral channel pump no vaporization of the fuel occurs and there prevails a sufficient resistance for maintaining the supply pressure of the lateral channel pump constant.

Claims

What is claimed is:

1. In a pump-and-motor unit for driving liquid, said unit being of the known type that has (a) a sealed housing defining a motor chamber, (b) a liquid inlet means and a liquid outlet means passing through said housing, (c) an electromotor disposed in said motor chamber and including an armature, (d) means, including bearing means, for rotatably supporting said rotary components of said electromotor, (e) a lateral channel pump disposed in said housing and having means defining a lateral channel, (f) an impeller forming part of said lateral channel pump and driven by said electromotor, the improvement comprising a pressure channel formed in said lateral channel defining means and extending inwardly from said lateral channel in a radial direction with respect to the rotary axis of said impeller, said liquid being driven into said lateral channel and from said lateral channel through said radially extending pressure channel toward said motor chamber.

2. An improvement as defined in claim 1, said impeller and said armature forming a unitary rotary assembly including channel means for guiding the liquid within said motor chamber, said last-named channel means terminating on the lateral surface of said armature.

3. An improvement as defined in claim 2, wherein said impeller being affixed to said armature by a plurality of radially extending laminar webs bounding said channel means, whereby said webs acting as vanes drawing liquid from said lateral channel pump and delivering it into said motor chamber.

4. An improvement as defined in claim 1, wherein said lateral channel defining means comprises a lateral channel plate containing said lateral channel, an annular groove provided in said lateral channel plate and arranged concentrically with respect to the rotary axis of said impeller, said radial pressure channel merging into said annular groove.

5. An improvement as defined in claim 4, said impeller and said armature forming a unitary rotary assembly adapted to be axially displaced, said rotary assembly including an additional annular groove facing the annular groove provided in said lateral channel plate, channel means provided in said rotary assembly for guiding the liquid within said motor chamber, said last-named channel means extending from said additional annular groove and terminating on the lateral surface of said armature.

6. An improvement as defined in claim 5, including a radial air gap defined between said lateral channel plate and said impeller, both said annular grooves being in communication with said radial air gap.

7. An improvement as defined in claim 6, said electromotor including stationary magnets disposed in said motor chamber spaced from said armature and offset with respect thereto in the direction of said lateral channel pump for biasing said impeller in the direction of said lateral channel plate.

8. An improvement as defined in claim 2, including a fixed shaft extending within said housing, said rotary assembly including an axial bore through which said fixed shaft passes.

9. An improvement as defined in claim 8, including

A. a valve channel provided in said lateral channel pump for connecting the pressure side of said lateral channel pump with the suction side thereof,

B. a valve plate movably supported on said shaft adjacent that side of said lateral channel plate that is remote from said rotary assembly, said valve plate controlling said valve channel,

C. a spring surrounding said shaft and engaging said valve plate and

D. an axially adjustable spring support means attached to said shaft and engaged by said spring.

10. An improvement as defined in claim 1, including

A. a unitary rotary assembly formed of said impeller and said armature,

B. a lateral channel plate comprising said lateral channel defining means, said plate being disposed axially spaced from said unitary rotary assembly, said lateral channel being provided on that face of said lateral channel plate that is oriented towards said unitary rotary assembly and

C. a cavity provided on said face of said lateral channel plate and being spaced downstream of said lateral channel and disposed at the same distance from the rotary axis of said impeller as said lateral channel, said cavity communicating with said radial pressure channel.

11. An improvement as defined in claim 10, including a channel portion provided in said face of said lateral channel plate, said channel portion constituting a downstream continuation of said lateral channel, said channel portion passing by said cavity at a distance therefrom and having a width smaller than that of said lateral channel.