Method and apparatus for the ventilation of a fuel supply pump

A method for the ventilation of fuel supply pumps as well as a new type of fuel supply pump are proposed which, particularly in pumps having two pumping stages coupled in series within the housing, serve to secure the ventilation of the first pumping stage. Preferably the first pumping stage is embodied as a lateral channel pump which has a forward anterior base plate. The ventilation bore is arranged axially at first in the base plate and in association with the lateral channel and is preferably formed during manufacture in one piece with the base plate; a reduction of the overly-large diameter of the ventilation bore is effected by the insertion of a reduction part to achieve the flow cross section required for ventilation. The ventilation to the outside of the lateral channel stage takes place via an external connection nozzle on the pump housing, which is secured thereon either axially or radially and can be embodied in one piece therewith as necessary. The connection of the ventilation bore of the lateral channel having a reduced cross section with the housing connection nozzle can be made by an elastic medially disposed member.

BACKGROUND OF THE INVENTION 
The invention relates to a method and apparatus for the ventilation of fuel 
supply pumps. Fuel supply pumps are already known in which the fuel 
pumping system and the electromotor are enclosed in a cup-shaped housing. 
It has already been proposed to embody the fuel supply pump in two stages, 
where the first stage is conventionally a lateral channel pump, while the 
second pump, coupled in series therewith and effecting the desired high 
final pressure, operates as a roller piston pump. Both fuel pumps, the 
lateral channel pump and the roller piston pump, are preferably arranged 
on a side that is oriented toward the collector of the driving 
electromotor. 
Problems arise with respect to the ventilation of the lateral channel in 
such pumps, in particular in two-stage fuel supply pumps having a 
forwardly disposed lateral channel pump. 
OBJECT AND SUMMARY OF THE INVENTION 
The method and apparatus claimed herein has the advantage that the 
ventilation of the lateral channel of the channel pump comprising the 
first stage, or in general the ventilation of the first stage of the pump, 
is possible in a simple and effective manner without great production 
expense; at the same time the throttle flow cross section required for the 
ventilation bore can be precisely maintained at the desired dimensions. A 
further advantage exists in that the axial and/or radial ventilation bores 
for the lateral channel in the base plate of the lateral channel pump can 
be formed in one piece with the base plate directly during manufacture and 
calibrated insertion bodies which have already been preassembled can then 
be pressed into these bores. 
By means of the dependent claims set forth in this application, 
particularly those which depend from the main method claim as well as 
those that depend from the main apparatus claim, further advantages of 
this invention over the prior art will be readily understood. Of 
particular advantage is the fact that the distance between the ventilation 
bore of the base plate or between the reduction part inserted therein and 
the associated opening of the ventilation nozzle which is secured on the 
housing is bridged by an elastic intermediary member, which besides 
providing a perfect seal assures that manufacturing tolerances in the 
positioning of parts in the area from the opening of the ventilation bore 
to the ventilation nozzle can be absorbed and equalized axially and 
radially. 
In a further advantageous embodiment the diversion out of the ring channel 
of the gases or vapors which arise during ventilation is effected by means 
of a bore that is transverse to the stationary axis in the base plate, 
which is extended in the direction of the induction nozzle and drilled out 
and serves in this form as a ventilation nozzle. In this way any further 
sealing againt the outside which may be required is avoided, namely the 
sealing of the ventilation nozzle in the housing and the tightness between 
the ventilation nozzle opening and the elastic intermediary member. 
The invention will be better understood as well as further objects and 
advantages thereof become more apparent from the ensuing detailed 
description of preferred embodiments taken in conjunction with the 
drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In order that the individual embodiments according to the invention may be 
better understood, the basic principle of a fuel supply pump will first be 
briefly described with the aid of the drawings in terms of structure and 
mode of operation. Particularly to be described is a two-stage fuel supply 
pump whose first pumping stage, located directly at the induction 
connection, which is preferably embodied as a lateral channel pump, is to 
be ventilated. In starting the pump and during operation, there are always 
gas or air bubbles in the supplied fuel, partly generated by thermal 
influence, which must be conducted away from the working area of the pump, 
so that its effectiveness is not reduced, as well as that failure in 
function during further treatment of the fuel up to the injection valves 
does not occur and additionally that the fuel supply performance does not 
break down. 
The fuel supply pump of FIG. 1 comprises a pumping area 1 made up of the 
two pumping stages 3 and 4 as well as the electromotor 2 which drives both 
pumps at once. The two pumping stages 3 and 4 are enclosed along with the 
electromotor in a cup-shaped housing 5, which has an induction connection 
6, as shown, and to which a fuel hose, not shown, is to be attached. The 
cup-shaped housing 5 is closed at one end thereof by means of a cover 
element 7, on which a pressure connection nozzle 8 and a recoil valve 9 
are arranged. Between the housing 5 and the cover element 7 a seal 10 is 
arranged with the cover element 7 being secured on the open end of the 
housing 5 by means of a deformed flange means 11. 
In the housing interior, as seen from the induction side toward the 
pressure side, first the two pumps 3 and 4 are arranged, then the 
electromotor 2; thus the fuel supplied under pressure by the pumps 3 and 4 
also flows through the electromotor 2 and its structural elements, in 
order to cool them. 
The electromotor 2 comprises a rotating core or motor armature 12 and a 
magnetic part 13. The motor armature 12 is fixed on a rigid shaft 15 by 
means of suitable bearings, for example journal bearings 14--14, the 
bearing parts in the forward housing area. In the illustrated embodiment, 
a base plate 16 is located forwardly in the pumping area 1 and will be 
described in greater detail below. This plate has a central bore 17, into 
which the shaft 15 is pressed. The other end of the shaft is loosely 
guided at 18 into a suitable bore of the cover element 7. 
The journal bearings 14--14 which support the motor armature 12 on the 
shaft 15 are arranged in a bearing tube 20, on which a laminated core 21 
and a core winding 22 are disposed. Furthermore, there is a commutator 
bushing 24 affixed to the bearing tube 20 and in this example secured by 
being pressed against it. 
Commutator brushes 25 slide on the commutator bushing 24 and are arranged 
in cage elements 26. The cage elements 26 are electroconductively 
connected with connecting terminals, not shown, in the cover element 7. 
The magnetic part 13 of the electromotor 2 comprises two permanent magnets 
27 which are arranged in a tubular or cylindrical holding part 28 and in 
the example are made of a magnetically conductive material and suitably 
shaped from sheet metal. This holding part 28 serves also to secure in an 
appropriate manner at least one stationary structural element in the 
pumping area 1, since a corresponding tension is exerted on the holding 
member 28 by the cover element 7 held by the flange means 11 via 
structural elements shown at 29 but not individually described. 
In the embodiment shown in FIG. 1, the clamping and compression pressure of 
the holding part 28 acts upon the forward base plate 16. The pumping area 
1 comprises, as mentioned earlier, two pumping stages 3 and 4 which are 
separate from each other and are driven simultaneously by the electromotor 
2. 
In the embodiment shown, the first pumping stage 3 directly oriented to the 
induction connection 6 comprises a lateral channel pump, while the second 
pumping stage coupled at the outlet side is embodied as a roller piston 
pump. The type and structure of the pumps comprising the pumping area can, 
however, be of any desired kind; each stage is to be viewed in the most 
general way as a fluid pump, which can be a gear-wheel pump, lateral 
channel pump, roller piston pump, or any other kind of pump needing 
ventilation. Between the particular movable parts of each pump, in other 
words, in the present embodiment between the impeller 30 of the lateral 
channel pump and the groove disc 31 of the roller piston pump, the motor 
armature 12 effects a rotary drive of the electromotor by means of a 
coupler tang 32 of the coupler 33 connected with the electromotor 2, said 
tang 32 projecting into a corresponding groove 34 of the groove disc 31. 
The coupler connection between the groove disc 31 and the impeller 30 is 
not separately illustrated. 
Proceeding from the induction connection 6, the pumping area is formed by a 
base plate 16, which on its side toward the impeller 30 comprises the 
stationary part of the lateral channel pump 3 which operates in connection 
with the impeller 30. The particular structure of the pumps comprising 
pumping stages 3 and 4 and their mode of operation need not be described 
here, since such fluid pumps (lateral channel pumps, roller piston pumps) 
are known to those skilled in the art. 
The forward base plate 16 contacts by means of oblique or chamfered 
surfaces 35 with correspondingly embodied opposing surfaces 36 in the 
interior of the housing; a seal 37 is inserted between neighboring ring 
surfaces of the interior housing wall and the forward base plate 16. The 
base plate 16 is held in its stationary position in the housing by the 
cylindrical holding member 28 already mentioned, which grasps a shoulder 
38 of the forward base plate 16, or else by an intermediate base plate 40 
if the holder grasps this part. Further, connected to the forward base 
plate, from left to right in the plane of the drawing, are the other 
structural elements comprising the pumping stages 3 and 4. First is the 
impeller 30 of the lateral channel pump, which can be fixed on the 
stationary shaft 15 by a journal bearing 39. This is then followed by the 
intermediate base plate 40, which with its peripheral ring flange or 
extension 41 overlaps the impeller of the lateral channel pump and rests 
with its flanged front wall 42 on a frontal wall ring flange of the 
forward base plate 16, or is secured thereto as needed. An intermediate 
plate 44 and then a support plate 45 are axially arranged next to the 
intermediate base plate 40 and all of these plates are suitably apertured 
as shown. The intermediate base plate 40, intermediate plate 44, and 
support plate 45 can be connected by means of screws 46, of which one is 
shown in FIG. 1, and can encompass among them the pump rotor or groove 
disc 31 of the roller piston pump, which is likewise fixed to the rigid 
shaft 15 by means of a suitable bearing 47. 
For the ventilation of the lateral channel of the lateral channel pump, a 
bore is arranged in the forward flange, that is, in the forward base plate 
16 of the lateral channel pump, which has a larger cross-sectional area 
than the flow cross section or the throttle bore which is desired or 
required for the degassing or ventilation of the lateral channel. The base 
plate 16 is embodied preferably as a die-cast part, in which a ventilation 
bore with the cross-sectional area of the flow cross section can be 
located only with difficulty. The bore cast in one piece and having a 
significantly larger cross-sectional area (for comparison purposes, 3 to 4 
mm) is thereafter reduced in its effective throttle cross-sectional area 
by means of a barrier element or insert 50 (see FIG. 2). This reduction 
part 50, which is pressed into the bore 51 of the base plate 16 and held 
as required by further means, such as a flanging of the substance making 
up the base plate, reduces the diameter of the bore 51 at least at one 
point on its axial extension to a cross-sectional area which corresponds 
to the flow cross section (for comparison purposes, 1 to 1.5 mm). 
The reduction part 50 can itself be of the corresponding flow cross section 
or throttle diameter for the ventilation; however, it can also be embodied 
as shown in FIG. 2, as an asymmetrical insert, by means of which the 
remaining free cross section forms a half-moon-shaped opening. In the 
embodiment of FIG. 2, the bore 51 is reduced at 52 and has a shoulder, so 
that the bore which has a larger diameter on the induction side becomes a 
bore part of smaller diameter toward the lateral channel. The reduction 
part 50 is correspondingly embodied in a complementary way; in the area 53 
of the bore 51 which has a larger diameter, the reduction part 50 has a 
ring-shaped wall 54 with a forward opening; in the area of reduced 
diameter of the bore 51 of the base plate 16, this is transformed into an 
area 56 which also has a half-moon-shaped cross section which with the 
opposing interior cylinder surfaces of the bore 51 forms the hydraulic 
opening 57. The opening 57 communicates via a connecting area with the 
interior space 55. 
Since, as was mentioned above, the pumping area is preassembled as a whole 
inside the housing 5, and a perfect seal of the base plate 16 is attained 
by the arrangement of the opposing surfaces 35 and 36 on the housing under 
the compression force of the flanging of the cover element, it is 
necessary to direct the ventilation area 55 toward the outside via a 
ventilation nozzle 58 which is tightly connected with the housing 5. This 
requires great radial and axial accuracy, and in accordance with a further 
characteristic of the present invention, the connection between the end 
part 59 of the nozzle 58 which projects into the interior of the housing 
and the opening beside it in the base plate 16 for the reduction part 50 
is formed by means of an elastic member 60. 
In the exemplary embodiment of the invention shown in FIG. 2, the elastic 
member is embodied as circular and is seated on a cross-sectional area 61 
of the nozzle end 59 which is narrowed, forming a shoulder. The elastic 
member 60 forms another forwardly narrowed end area 62, with which it 
projects into the bore of the reduction part 50. In accordance with the 
embodiment of FIG. 2, the elastic member 60 surrounds the tapered end area 
61 of the ventilation nozzle, which projects still further into the hollow 
space 55 of the reduction part 50. 
The elastic member 60 accommodates in an advantageous way the tolerances 
resulting at this point, which are sometimes very great in a radial and/or 
axial direction; the requirements for accuracy in manufacture are reduced 
by simultaneous precise sealing of the ventilation bore in the base plate 
16 which leads to the outside and is reduced to the flow cross section. 
The connection of the ventilation nozzle 58 with the front wall of the 
housing can be effected in many different ways, e.g., it is possible to 
provide the housing wall directly with a second smaller ventilation nozzle 
in addition to the induction connection nozzle 6 at the time of 
manufacture. Since the housing is embodied preferably as an aluminum 
extrusion-molded part, the ventilation nozzle 58a, as shown in FIG. 3, may 
be formed in one piece with the housing at the same time. It is, however, 
also possible, as the exemplary embodiment of FIG. 2 shows, to attach a 
separate ventilation nozzle later during assembly. The ventilation nozzle 
is guided through a bore 65 of the frontal surface of the housing and 
secured from the outside by a clamping means 66 which extends 360.degree. 
around the circumference with the arrangement on the inside of the housing 
being effected by means of a shoulder 67. For further sealing, a so-called 
"Loc-tite" sealing means can be provided in the area where the ventilation 
nozzle 58 enters the frontal surface of the housing. 
The elastic member 60 provided between the end area 59 of the ventilation 
nozzle 58, the area 59 which projects into the interior and includes a 
shoulder, and the bore in the base plate 16 which is narrowed by the 
insertion of the reduction part 50 can be made of any convenient 
substance, for example a plastic with an appropriate degree of hardness or 
an elastomer, caoutchouc, rubber, or the like. The substance must be 
resistant to the effect of fuel, that is, to the effect upon it of 
hydrocarbon bonds in general. 
FIGS. 2a and 2b illustrate further possible embodiments for the extension 
of the ventilation nozzle 58' or 58" through the bore 65 of the frontal 
wall of the housing 5. In FIG. 2a the tubular ventilation nozzle 58' is 
guided through the frontal wall and then secured by a circular ridge 70 so 
that there is a firm tension connection. The seal here as well as can be 
effected again by means of an adhesive substance such as "Loc-tite". 
In the embodiment of the invention shown in FIG. 2b the ventilation nozzle 
58" is preferably made of a molded plastic substance which is formed in 
the shape of a nozzle and arranged to extend through an aperture in the 
housing 5. To effect a sealing connection between the plastic nozzle and 
the bore 65 in the housing, the area through which the bore extends can be 
painted with an appropriate adhesive or varnish before the plastic nozzle 
is molded thereon, and then the deformed areas 80 and 80a grasp on both 
sides of the bore in order to support the nozzle securely in the bore. In 
the embodiment of FIG. 2b, it will also be noted that the nozzle end area 
59" which extends into the interior of the housing tapers in the fashion 
of a truncated cone and projects into a complementally cone-shaped opening 
81 associated with the nozzle end area 60a. 
It is further significant that in all embodiments, including those to be 
described below, the transition surfaces between the elastic member and 
the reduction part on one side and the associated end of the ventilation 
nozzle on the other side are tight as a result of a corresponding 
compression effect resulting from the flanging inward of the covering. 
Obviously the connection between the elastic member and the ventilation 
nozzle and/or reduction part can, as desired, be effected by adhesion or 
by other connection techniques; it is also possible to vulcanize the 
elastic member onto the nozzle end area. Such a procedure is particularly 
valuable when the corresponding wall parts of the elastic member and the 
nozzle end area come into contact with each other in the assembly as in 
the exemplary embodiment of FIG. 2a. 
It was noted above that in the embodiment of FIG. 3 that the ventilation 
nozzle 58a which projects outward is a component formed in one piece with 
the housing, which is embodied as an aluminum extrusion part. Thus, in 
this embodiment the distance between the reduced ventilation bore of the 
base plate 16 and the ventilation nozzle 58a or the opening in the 
interior housing wall formed thereby is bridged completely by the elastic 
member 60b. To achieve an improved seating of the flexible member 60b it 
is formed in the manner of a nipple and includes a chamfered front wall 92 
that is complemental to the shape of the inner wall denoted 90. As shown 
the nipple is supported on the short pipe extension 91. Thus it can be 
readily understood that the conically tapered tip 92 of the elastic member 
60b is forced under pressure within the opening area or the opening cone 
of the ventilation nozzle opening. Further, it will be understood that in 
this embodiment of the invention, particularly large radial and axial 
tolerances can be absorbed. 
The ventilation systems shown in FIGS. 4 and 5 are different from the above 
embodiments, for here, the axial ventilation channel in the base plate 16 
is rotated by a 90.degree. angle and arranged to extend in a radial 
direction. 
In the embodiment of FIG. 4, the base plate 16 has two openings or bores in 
communication with each other, namely a channel 100 which extends axially 
from the lateral channel of the lateral channel pump 3 toward the frontal 
wall on the induction side, and then a radially directed transverse 
channel 101 branches off therefrom approximately in the center of the base 
plate 16. Both bores or channels 100, 101 can be formed by molding at the 
time the base plate 16 is produced, in which case the inclusion of a core 
insert 102 which forms the reduction part is made easier by the guiding of 
the axial bore 100 through to the end surface on the induction side of the 
base plate 16. At this point the bore is widened and a shoulder 103 
formed, so that when the core insert which serves as a reduction part to 
produce the flow cross section is placed in position, its annular flange 
104 abuts the shoulder 103. Here, as well, a firm seat can be provided by 
an inward flanging or upsetting of the material of the base plate 16 to 
form stop elements 105 from the substance of the extended bore part 106. 
The effective throttle cross-sectional area is formed as at 57'. The 
transverse bore 101, which is associated with the axial bore 100, opens 
into an annular space between the base plate 16 and the housing 5, from 
which the air or vapor is ventilated by means of a ventilation nozzle 110 
that extends outwardly in a radial direction. In this exemplary 
embodiment, sealing problems with respect to the introduction of the 
sealing nozzle 110 into the housing wall do not arise, since the circular 
space 109 is sealed off both on the compression side and the induction 
side, that is, on the one side by a sealing means 37 and on the other by 
the surfaces 35, 36 of base plate 16 and housing 5 which are in firm 
contact with each other. The ventilation nozzle 110 can be introduced into 
the bore 111 of the lateral wall of the housing in any convenient manner, 
for example, as is shown in FIG. 4, by holding with a circular torus, or 
as in FIG. 4a with the aid of a sealing element 120 vulcanized thereon and 
made of an elastomer, for example rubber, in which case the ventilation 
nozzle is held by clamping bands or brackets 121 on both sides. 
The ventilation nozzle opens in accordance with the object of the invention 
into the interior of the fuel tank by means of a hose connection attached 
to it, so that fuel particles (fuel vapor) carried along with it are 
redirected to the fuel reserve. 
In the embodiment of FIG. 5 as well, a radial transverse bore 130 is 
provided between the axial channel 100 which is provided with the core 
insert 102 and the ventilation nozzle; however, here this bore solely 
represents a radial intermediate bore between two axial sections. The 
ventilation nozzle 58b is arranged concentrically within the induction 
connection nozzle 6 in this embodiment and is formed of a central 
extension 140, which is set into an aperture in the base plate 16 and 
preferably embodied in one piece with the stationary shaft 15' pressed 
into the base plate 16. For this purpose, the extension piece of the axis 
140 has a central bore 141, which opens at 142 into a transverse bore 143 
of the shaft 15'. The shaft 15' is surrounded at this point by the 
circular space 144, which opens into the radial transverse bore 130. The 
transverse bore 130 and the vertical bore 100 extend for the sake of 
efficiency through the substance of the base plate 16 to the appropriate 
end wall, so that the reducing core insert 102 can be introduced into the 
axial bore 100, while the transverse bore 130 is so embodied to make its 
manufacture much easier. It is further also preferably slightly 
cone-shaped, so that after manufacture the core parts are more easily 
removed. A double-walled hose with a coaxial interior hose member is then 
required to divert the ventilated air, gas, and vapors. On the other hand, 
the advantage results that only a single hose is necessary for both the 
carrying of fuel to the induction nozzle 6 and the ventilation of the 
pump, and only a single nozzle needs to be inspected as to the firmness of 
its seating. 
Two further alternative embodiments may be finally seen in FIGS. 6 and 7; 
common to both is the fact that the housing is open on its frontal side 
and has only a single ring flange 150a (FIG. 6), 150b (FIG. 7) each of 
which retain the base plate 16' securely in position. 
In the embodiment of FIG. 6, the annular flange 150a of the housing 5 
secures the forward base plate 16' of the lateral channel pump directly 
and firmly, said base plate 16' bearing the induction nozzle 6a and a 
ventilation nozzle 58c. In this way the housing is much more simply 
constructed; the seal between the housing wall and the base plate is 
accomplished by the compression seating achieved through the flanging 
means referred to above. An additional sealing means 160 can also be 
provided as shown. The base plate 16' comprises an aluminum 
extrusion-molded part. The tightness of the shaft 15 with respect to the 
surrounding area is also accomplished by the compression seating between 
the shaft axis and the forward base plate 16'. In this case as well no 
elastomeric connecting member is necessary between the axial ventilation 
bore 161 and the ventilation nozzle 58c, since the latter opens in one 
piece into the former. The reduction part 162 is secured in a suitable 
manner in the ventilation bore, for example as shown in FIG. 4, by means 
of an upsetting or deforming action of the material adjacent to the 
opening so as to form areas 105 where the ventilation bore 161 opens into 
the ventilation nozzle 58c. 
Alternatively a separate cover element 170 on the induction side can be 
employed, as shown in FIG. 7, which cover element is held by the annular 
flange 150b of the housing 5 which is turned radially inward and which 
complements with its inner shape of the wall the contour of the base plate 
16" in contact with it. Induction nozzle 6b and ventilation nozzle 58d are 
formed in one piece with the cover element 170. Since in this case the 
cover element 170 which faces the housing interior can form a larger 
circular surface 171 around the interior bore of the ventilation nozzle 
58d, the sealing of the axial ventilation bore, with its inserted 
reduction member 162' which is held by flanging means, against the gas 
over-pressure is accomplished by means of the perfect plane alignment of 
the circular surface 171 with a corresponding circular surface of the base 
plate 16" and by means of a fluid sealing. 
Since two cast parts are disposed on each other in the embodiment shown in 
FIG. 7, namely the cover element 170 and the base plate 16", the 
possibility arises of effecting sound insulation by means of the 
intermediate positioning of a compressible structural element 172. The 
compressible structural element 172 can be embodied as an air-filled hose, 
cushion, or the like. 
The foregoing relates to preferred embodiments of the invention, it being 
understood that other embodiments and variants thereof are possible within 
the spirit and scope of the invention, the latter being defined by the 
appended claims.