Fuel injector with solenoid and terminal assemblies

A fuel injector includes an injector body defining a terminal passage extending between a solenoid cavity and an outer surface. A solenoid assembly is press fit attached to the injector body and received in the solenoid cavity. The solenoid assembly includes a bobbin sandwiched between an upper magnetic flux carrier and a lower magnetic flux carrier. At least one of the flux carriers is plastically deformed when the solenoid assembly is attached to the injector body. A terminal assembly has an external terminal, an electrical conductor and a sealing member surrounding a portion of the electrical conductor. A portion of the electrical conductor and the sealing member are received in the terminal passage. A clamp is in contact with the outer surface of the injector body and the terminal assembly.

TECHNICAL FIELD 
The present invention relates generally to electronically controlled fuel 
injectors, and more particularly to solenoid and terminal assemblies for 
fuel injectors. 
BACKGROUND ART 
An example of an electronically controlled fuel injector is shown in U.S. 
Pat. No. 5,551,398 to Gibson et al. Fuel injection is controlled in this 
injector with a single solenoid that has the ability to move two separate 
armatures. A fuel spillage valve member is attached to a first armature, 
and a needle control valve member is attached to a second armature. When 
the spill valve member is in its open position, fuel pressure cannot build 
within the fuel injector. Upon closing the spill valve member, fuel is 
trapped within the injector and a plunger moves downward to pressurize 
fuel. The plunger is mechanically driven downward by a cam/rocker arm and 
tappet assembly. When fuel pressure builds within the injector and the 
needle control valve member is in its on position, fuel will commence to 
spray out of the nozzle outlet when the fuel pressure is above a valve 
opening pressure sufficient to overcome a needle check return spring. When 
fuel pressure is high and the needle control valve member is in its off 
position, high pressure fuel is directed to a closing hydraulic surface on 
one end of the needle check to close the same to provide an abrupt end to 
an injection event. 
In this injector, the solenoid must necessarily be positioned deep within 
the injector body, and electricity to energize the solenoid must be 
brought from the outside of the injector body to the solenoid assembly. In 
this prior art injector, the solenoid assembly is glued into the injector 
body. Engineers are often seeking ways to improve the sealing of the 
injector body against leakage, especially where the electrical conductors 
penetrate the injector body. Furthermore, engineers are often looking for 
ways to improve solenoid assemblies and terminal assemblies in order to 
decrease complexity during production by making the terminal and solenoid 
assemblies as separate integral components with decreased part counts. In 
addition, by improving the mating between these sub assemblies and an 
injector body, the robustness and working life of an injector when fully 
assembled can be improved. 
The present invention is directed to improving solenoid assemblies, 
terminal assemblies and fuel injectors that utilize both. 
DISCLOSURE OF THE INVENTION 
A valve terminal assembly includes a valve body defining an inner cavity, 
an outer surface and a terminal passage extending between the inner cavity 
and the outer surface. A terminal assembly has an external terminal and 
one of a male electrical connector and a female electrical connector 
attached to a terminal housing. A portion of the terminal assembly 
containing the electrical connector is received in the terminal passage. A 
clamp is in contact with the valve body and the terminal assembly. 
In another embodiment of the present invention, a solenoid assembly 
includes a coil assembly having a bobbin with a wire winding. An upper 
magnetic flux carrier is attached to a lower magnetic flux carrier with 
the bobbin positioned there between. One of a male electrical connector 
and a female electrical connector is attached to the bobbin. 
In still another embodiment of the present invention, a fuel injector 
includes an injector body defining a solenoid cavity, an outer surface and 
a terminal passage extending between the solenoid cavity and the outer 
surface. A solenoid assembly includes a coil assembly sandwiched between 
an upper magnetic flux carrier and a lower magnetic flux carrier. The 
solenoid assembly is press fit attached to the injector body and received 
in the solenoid cavity. At least one of the magnetic flux carriers are 
plastically deformed when the solenoid assembly is attached to the 
injector body. A terminal assembly has an external terminal, an electrical 
conductor and a sealing member surrounding a portion of the electrical 
conductor. A portion of the electrical conductor and the sealing member 
are received in the terminal passage. The sealing member is in sealing 
contact with the valve body within the terminal passage. A clamp is in 
contact with the outer surface of the injector body and the terminal 
assembly.

BEST MODE FOR CARRYING OUT THE INVENTION 
In the drawings, the same reference numerals designate the same elements 
for features throughout all of the drawings. 
Referring now to FIG. 1, a mechanically actuated electronically controlled 
fuel injection system 10 is illustrated. The system includes a plurality 
of fuel injectors 11 (only one of which is shown) having an injector body 
12, a nozzle outlet 13 and a tappet 14. With each revolution of an engine, 
a cam 76 is rotated in contact with rocker arm assembly 77. With each 
rotation of cam 76, tappet 14 is driven downward to pressurize fuel within 
injector 11. Fuel is supplied to injector 11 from a fuel tank 20. Fuel is 
drawn from tank 20 by a relatively low fuel transfer pump 21 through fuel 
filters 22 and into fuel supply passage 23. A fuel return passage 24 
connects a spill passage within injector 11 with fuel tank 20 to 
recirculate spilled fuel. A solenoid actuated control valve within 
injector 11 receives power via a terminal assembly 30 that is clamped via 
a circumferential band clamp 80 to the outer surface of injector 11. An 
electronic control module 78 controls the energization and de-energization 
of the solenoid within injector 11 via a communication line (i.e. current) 
79 in a conventional manner. 
Referring now to FIG. 2, a fuel injector valve terminal assembly 15 is 
illustrated. The assembly includes an injector body component 12 made from 
a suitable metallic alloy into a generally cylindrical shape about a 
centerline 19. Valve body component 12 is machined to include an inner 
solenoid cavity 16 and a terminal passage 27 extending between solenoid 
cavity 16 and an outer surface 17. The centerline 31 of terminal passage 
27 is preferably oriented at an angle on the order of about 15.degree. to 
25.degree. with respect to the centerline 19 of injector valve body 
component 12. A solenoid assembly 50 is press fit attached to body 
component 12 and received in solenoid cavity 16. In particular, a raised 
annular ridge 51 is partially plastically deformed when solenoid assembly 
50 is pressed into inner cavity 16 and raised annular ridge 51 comes in 
contact with press fit interference zone 26, which defines a portion of 
the cavity. The term "annular" includes less than a full circle in the 
case of annular ridge 51 because in some instances it may be desirable to 
include a slit to accommodate plastic cover 56, etc. A portion of solenoid 
cavity 16 is a grommet cavity 28 that receives a grommet seal 52, which is 
a portion of solenoid assembly 50. The sealing contact between grommet 
seal 52 and grommet cavity 28 is intended to at least partially prevent 
fuel or another fluid surrounding solenoid assembly 50 from coming into 
contact with a male/female electrical connection 48 that is used to supply 
current to the coil within solenoid assembly 50. 
A terminal assembly 30 is mated to solenoid assembly 50 and injector body 
12. Terminal assembly 30 includes a plastic terminal housing 33 shaped to 
include a rounded contact surface 35 that conforms to outer surface 17 and 
a locating projection 32 that is positioned in contact with a locating 
surface 18. Terminal assembly 30 held in place with a circumferential band 
clamp 80 that is in contact with both terminal assembly 30 and outer 
surface 17 of body component 12. A portion of terminal assembly 30 
containing an electrical conductor is received in terminal passage 27. 
Terminal passage 27 has an enlarged diameter portion, a reduced diameter 
area 25 and a pin face seal area 29. A portion of terminal assembly 30 is 
a sealing member 34 that surrounds an inner electrical conductor. Sealing 
member 34 is tapered to ensure that somewhere along its length appropriate 
compression takes place to seal terminal passage 27. Sealing member 34 
makes sealing contact with terminal passage 27 in order to further prevent 
the leakage of any fluid that gets past grommet seal 52 from escaping to 
outer surface 17. A different portion of sealing member 34 comes in 
contact with pin face seal area 29 to prevent entry of contaminates from 
outside of body component 12 into solenoid cavity 16. Sealing member 34 is 
compressed against pin face seal 29 to produce a mechanical preload when 
locating projection 32 is positioned against locating surface 18. This 
preload maintains locating projection 32 in contact with locating surface 
18 to ensure that terminal assembly 30 is properly located and stabilized 
during vibrations. Terminal assembly 30 includes one of a male electrical 
connector and a female electrical connector, and solenoid assembly 50 
includes the other of a male and female electrical connector. 
Referring now to FIGS. 3 and 4, terminal assembly 30 includes a pair of 
external terminals 42 electrically connected to a pair of male electrical 
connectors 40 via a pair of separate electrical conductors 43. A plastic 
terminal housing 33 is molded, preferably of nylon, around a portion of 
the electrical components to include rounded contact surface 35, locating 
projection 32, a connector receptacle opening 37, and a clamping surface 
36. Another portion of the electrical components has a sealing member 34, 
preferably made of a rubber type material, molded there around. Sealing 
member 34 includes a tapered portion 38 to create an appropriate seal when 
received in terminal passage 27. An annular face seal 41 comes in sealing 
contact with pin face seal 29 when terminal assembly 30 is mated to 
injector valve body component 12 as shown in FIG. 2. Terminal assembly 30 
is preferably an integral component consisting essentially of only five 
attached parts: a pair of electrical conductors, a terminal housing 33 and 
a pair of sealing members 34. 
Referring now to FIG. 5, the inner structure and outer shape of solenoid 
assembly 50 are illustrated. Solenoid assembly 50 includes a coil assembly 
having a bobbin 59 with a wire winding 62 sandwiched or positioned between 
an upper magnetic flux carrier 58 and a lower magnetic flux carrier 57. 
The magnetic flux carriers are preferably made from a material such as 
soft silicon steel. Upper and lower magnetic flux carriers 58 and 57 are 
attached to one another through a press or crush fit such that one or both 
undergo a permanent plastic deformation where the two pieces contact. In 
this case, upper magnetic flux carrier 58 includes an annular insert 
portion 64 that deforms when it is received in a counterbore lower 
interference zone 63 formed in lower magnetic flux carrier 57. Lower 
magnetic flux carrier 57 includes a raised annular ridge 51, as discussed 
earlier, that plastically deforms creating a press fit when solenoid 
assembly 50 is received in solenoid cavity 16. Thus, the only real contact 
between solenoid assembly 50 and injector body component 12, when 
assembled, exists between raised annular ridge 51 and press fit 
interference zone 26, and the contact between grommet seal 52, which is 
preferably made from a non-electrically conducting resilient material such 
as rubber, and grommet cavity 28. 
Upper magnetic flux carrier 58 includes a slot that allows a plastic 
carrier 55 and electrical conductor 65 to be attached to bobbin 59. 
Electrical conductor 65 includes a female electrical connector 54 
concealed within grommet seal 52. A plastic cover 56 protects the 
otherwise exposed portion of electrical conductor 65, which is attached to 
exposed leads of wire winding 62. When assembled, upper magnetic flux 
carrier 58, bobbin 59 and lower magnetic flux carrier 57 share a common 
centerline 61 and define a central cylindrical cavity, within which are 
positioned a pair of armatures when the injector is fully assembled. After 
the various components of solenoid assembly 50 are positioned and attached 
as shown, epoxy is injected in the area around bobbin 59 and the other 
components in order to make solenoid assembly 50 behave as an integral 
component, to ease assembly during production. The female electrical 
connectors 53 and 54 of solenoid assembly 50 mate with the counterpart 
male electrical connectors 40 of terminal assembly 30 when the two 
assemblies are attached to injector valve body component 12 as shown in 
FIG. 2. 
The female electrical connectors 53 and 54 are oriented at about the same 
angle with respect to common centerline 61 as terminal passage centerline 
31 is oriented with respect to body centerline 19. 
INDUSTRIAL APPLICABILITY 
The present invention finds potential application in any valve that 
utilizes a solenoid that is positioned within the valve body. The present 
invention is particularly applicable for incorporation into the design of 
electronically controlled fuel injectors. The present invention is 
particularly applicable as an improvement on one class of mechanically 
actuated electronically controlled fuel injectors of the type manufactured 
by Caterpillar, Inc. of Peoria, Ill. and described for instance in U.S. 
Pat. No. 5,551,398 to Gibson et al. 
Referring back to FIG. 2, when the various components are assembled, 
solenoid assembly 50 is first press fit into attachment with body 
component 12. Next, the male electrical connector portions of terminal 
assembly 30 are advanced through terminal passage 27 until locating 
protrusion 32 can be positioned against locating surface 18. The mating of 
these two surfaces ensures that an adequate electrical mating connection 
exists between the male and female electrical connectors. In addition, the 
terminal assembly is preferably designed such that the positioning of the 
locating surfaces ensures that the sealing member 34 is in its proper 
position to both maintain against leakage from the inside of body 
component 12 to the outside, and vice versa. The use of a circumferential 
clamp 80 combined with the orientation of locating surface 18 ensures that 
terminal assembly 30 cannot work itself loose from its position attached 
to body component 12 when a complete injector experiences vibrations and 
other disturbances during its working life. Because the solenoid assembly 
50 and terminal assembly 30 are essentially separate integral components, 
assembly of complete injectors is significantly simplified over the 
multi-component sub assemblies of the prior art. The present invention 
prefers the use of a circumferential band clamp to hold terminal assembly 
30 in place, but other clamping means, such as a retaining ring, etc. 
could be substituted in its place. In addition, in some instances, the use 
of fasteners may be possible if the same can be accomplished without 
weakening or otherwise causing distortion to the valve body component 12, 
which often is a highly stressed component in a fuel injector. Thus, 
fasteners can also be considered as clamps in relation to the present 
invention. 
Those skilled in the art will appreciate the numerous modifications and 
alternative embodiments of the present invention that are apparent in view 
of the foregoing description. Accordingly, this description is to be 
construed as illustrative only, and is for the purpose of teaching those 
skilled in the art the best mode of carrying out the invention. The 
details of the structure may be varied substantially without departing 
from the spirit of the invention, the scope of which is defined in terms 
of the claims as set forth below.