Inductor devices – Coil or coil turn supports or spacers – Coil on a preformed support or mount
Reexamination Certificate
2001-05-08
2002-12-24
Mai, Anh (Department: 2832)
Inductor devices
Coil or coil turn supports or spacers
Coil on a preformed support or mount
C336S198000, C336S110000
Reexamination Certificate
active
06498558
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates in general to solenoid valves for electronic brake control systems and in particular to a solenoid valve coil wound upon an integrated bobbin and flux ring assembly.
An Electronic Brake Control System (EBCS) is often included as standard equipment on new vehicles. When actuated, the EBCS is operative to modulate the pressure applied to the vehicle wheel brakes. A typical EBCS includes a plurality of solenoid valves mounted within a control valve body and connected to the vehicle hydraulic brake system between the brake master cylinder and the individual wheel brake cylinders. The solenoid valves usually are normally open, or isolation, valves and normally closed, or dump, valves. Proportional solenoid valves also can be included. The valve body further includes one or more accumulators for the temporary storage of brake fluid during an operating cycle of the EBCS.
A separate hydraulic source, such as a motor driven pump, is usually included in the EBCS. The pump supplies pressurized brake fluid for reapplying the controlled wheel brakes during an EBCS operational cycle. The pump is typically included within the control valve body while the pump motor is mounted upon the exterior of the control valve body. The pump motor is usually a direct current motor which operates from the vehicle power supply. Typically, the motor runs continuously during an EBCS braking cycle.
An EBCS further includes an electronic control module which has a microprocessor. The microprocessor is electrically connected to the pump motor, a plurality of solenoid coils associated with the solenoid valves, and wheel speed sensors for monitoring the speed and deceleration of the vehicle wheels. The microprocessor also is typically electrically connected to the brake light switch and receives a signal from the switch when the vehicle brakes are applied. Additionally, the EBCS may include one or more accelerometers which also are connected to the microprocessor. The microprocessor includes a memory portion which stores control algorithms for each mode of operation of the EBCS. The control algorithms comprise a set of instructions for the microprocessor which control the operation of the EBCS. The control module is usually mounted upon the valve body. The assembled valve body, motor and control module form a compact unit which is often referred to as an electro-hydraulic control unit.
During vehicle operation, the microprocessor in the EBCS control module continuously receives speed signals from the wheel speed sensors. Depending upon the received signals, the microprocessor can select one of several modes for operation of the EBCS. For example, if the microprocessor detects a potential wheel lock-up condition while the vehicle brakes are applied, the microprocessor will select an Anti-Lock Brake System (ABS) mode of operation and activate an ABS braking cycle. During an ABS braking cycle, the microprocessor actuates the pump motor and selectively operates the solenoid valves in the control valve to cyclically relieve and reapply hydraulic pressure to the wheel brakes. The hydraulic pressure applied to the wheel brakes is adjusted by the operation of the solenoid valves to limit wheel slippage to a safe level while continuing to produce adequate brake torque to decelerate the vehicle as desired by the vehicle operator.
Another mode of operation provides Traction Control (TC). If the microprocessors detect excessive slip of a driven wheel when the wheel brakes are not applied, the EBCS will apply the brakes to the slipping wheel and thereby transfer more engine torque to the non-slipping wheel.
The EBCS can also include Vehicle Stability Control (VSC) mode of operation. The VSC mode is entered when the microprocessor detects a potential loss of directional control, such as, for example, a spin-out of the vehicle. In the VSC mode of operation, selected wheel brakes are applied to restore directional control of the vehicle.
Referring now to
FIG. 1
, there is shown a partial sectional view of a typical EBCS solenoid valve
10
mounted upon an EBCS control valve body
11
. The control valve body includes a plurality of internal passages (not shown) that communicate with the valve
10
. The valve
10
is a digital valve, that is, it is either open or closed. The particular valve
10
shown in
FIG. 1
is a normally open valve, however, the following discussion also applies to normally closed valves. The valve
10
includes an axially shiftable armature (not shown) which is biased in an upward direction by a spring (not shown) such that a ball valve (not shown) is maintained in a normally open position. The ball valve cooperates with a valve seat member
15
which is mounted in the valve body
11
. The armature and ball valve are slideably disposed within a valve sleeve
16
having a closed end.
A solenoid coil
20
is carried by the valve sleeve
16
and surrounds the armature
12
. The coil
20
is enclosed by a cup shaped metal flux casing
21
. The valve sleeve
16
extends through an aperture
22
formed in the upper end of the flux casing
21
. An annular flux ring
23
is disposed in the open lower end of the flux casing
21
. The flux casing
21
and flux ring
23
complete a magnetic flux path which passes through the armature and the valve seat member
15
.
The solenoid coil
20
is of conventional design, comprising a winding
24
formed from multiple turns of an insulated magnet wire having a round cross section, such as #28 ½ magnet wire. The magnet wire is helically wound upon a plastic bobbin
26
. The bobbin
26
has a cylindrical center portion
28
that terminates in upper and lower flanges,
30
and
32
, respectively. A pair of terminal pin supports
34
extend in an axial direction from the top of the bobbin
26
. Each of the supports
34
is molded over a terminal pin
36
. An end
38
of the coil winding wire is wound around the base of each of the terminal pins
36
and soldered thereto. The pins
36
are electrically coupled to via a printed circuit board (not shown) to the EBCS microprocessor.
When it is necessary to actuate the valve
10
during an anti-lock braking cycle, an electric current is supplied through the terminal pins
36
to the solenoid coil
20
. The current establishes a magnetic field in the armature which pulls the armature in a downward direction, closing the ball valve. When the current is interrupted, the magnetic field collapses, allowing the spring to return the armature to its original position, thereby reopening the ball valve. An EBCS control unit also typically includes other digital solenoid valves, such as normally closed solenoid valves (not shown), which have structures similar to the normally open valve
10
described above. Additionally, an EBCS control unit can include proportional solenoid valves.
SUMMARY OF THE INVENTION
This invention relates to a solenoid valve coil wound upon an integrated bobbin and flux ring assembly.
For electronic brake control systems being currently developed, vehicular solenoid valves can be energized for long periods of time. The energized coils generate heat that must be conducted away from the coils to avoid overheating. Conventional coil bobbins typically have air gaps and low-pressure contacts between the bobbins and the metal parts of the other components of the control system. Accordingly, current units have poor heat conduction properties. Therefore, a coil assembly having improved heat conduction properties would be desirable.
The present invention contemplates a bobbin assembly for a solenoid valve coil that includes a bobbin formed from an electrically insulative material with a bore extending axially therethrough. The bobbin assembly further includes a flux ring formed from a magnetically permeable material having a high heat conductivity. The flux ring has an annular base portion and a tubular sleeve extending axially into an end of the bobbin bore. The bobbin has a pair of flanges formed upon the ends thereof. A winding is wound upon the bobbin between s
Anderson Robert
Linkner, Jr. Herbert L.
Kelsey-Hayes Company
MacMillan Sobanski & Todd LLC
Mai Anh
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