[0001] This invention relates to vacuum regulators in general and in particular to electric
or electronic vacuum regulators for use with internal combustion engines.
[0002] In the engine systems of motor vehicles, vacuum regulators are used to control the
vacuum which is created in the engine and used to operate many of the various pollution
control devices. As with any control source, and vacuum sources are no different,
it is a requirement that the control value of the source be either regulated or always
known. If the source is to be regulated or maintained at a single fixed value, then
the conventional mechanically constructed vacuum regulator comprising springs, diaphragms
and orifices perform adequately.
[0003] In the modern internal combustion engine control system, computers having one or
more microprocessors and read-only-memories (ROM) are being programed to generate
electrical signals of various values. As certain engine operating parameters or conditions
change, the computer through digital mapping techniques can generate unique control
signals representing the present state of the engine. One such control signal may
represent a vacuum level for controlling a vacuum utilization device.
[0004] Combining such control signal as generated by a computer with a prior art vacuum
regulator, the single fixed value of vacuum can be maintained. Such prior art vacuum
regulators have a rubber diaphragm for separating the vacuum and atmospheric chambers.
An armature is attached to the diaphragm, and to form the regulating part of the valve,
a seal is placed between the armature and the rubber diaphragm. As the armature moves
reciprocally, the seal wears causing the regulator calibration to drift. To further
complicate matters, in order to complete the magnetic circuit a steel member must
be added thereby increasing the number of elements making up the regulator.
[0005] In order to avoid the subsequent wear and drift of regulator and to maintain accurate
vacuum regulation, the present electric vacuum regulator was developed. One element,
a steel disk or armature separates and provides a seal between the vacuum and atmospheric
chambers and completes the magnetic circuit for the solenoid actuator. Because it
seals on a brass seat, wear of the internal members of the regulator is virtually
eliminated.
[0006] There is disclosed and claimed herein an electric vacuum regulator having an input
port for connection to a vacuum source such as manifold vacuum in an internal combustion
engine. A vacuum operated device such as an exhaust gas recirculation valve is connected
to an output port .of"the regulator. Within the regulator, a mixing chamber interconnects
the two ports and positioned within the chamber is an orifice which is connected to
a source of air pressure such as atmosphere. A steel disk is adapted to seal the orifice
from the chamber and since this is an electrically operated regulator, a coil surrounds
a stator for generating magnetic flux causing the disk to be attracted towards the
seat. The coil is energized by a unique duty cycle control signal generated in the
computer in response to the operating conditions of the engine. As is conventional
in vacuum operated devices, a bias spring is placed to maintain the disk in a position
closing the orifice when there is no electrical signal and no vacuum.
[0007] These and other advantages of the electric vacuum regulator will become apparent
from the following detached description and drawings in which:
Fig. 1 is a schematic block diagram of control system utilizing the positive gain
electric vacuum regulator of the present invention;
Fig. 2 is a longitudinal sectional view taken along an axis of a positive gain electric
vacuum regulator as may be used in the system of Fig. l;
Fig. 3 is a longitudinal sectional view taken along an axis of a negative gain electric
vacuum regulator;
Fig. 4 is a graph of the operation of the positive gain electric vacuum regulator
of Fig. 2; and
Fig. 5 is a graph of the operation of the negative gain electric vacuum regulator
of Fig. 3.
[0008] Referring to the Figs. by the reference numerals, a system is illustrated in Fig.
1 as may be found on an internal combustion engine of a motor vehicle. The vacuum
utilization device is an exhaust gas recirculation (EGR) valve 10 which operates under
certain engine operating conditions to recirculate, from the exhaust manifold 12 to
the intake manifold 14, exhaust gas into the air-fuel mixture. Connected to the vacuum
input 16 of the EGR valve 10 is the output port 18 of the electric vacuum regulator
(EVR) 20 and an input port 22 of a vacuum switch 24.
[0009] The vacuum switch 24 functions to determine the presence of vacuum in the vacuum
line to the EGR valve 10. If a vacuum hose is off or if the diaphragm is bad or if
the EVR 20 is defective or if there is any other condition which adversely affects
the vacuum level, the vacuum switch 24 generates a signal to the electronic control
unit (ECU) or onboard computer 26.
[0010] The function of the ECU 26, as far as the present invention is concerned, is to map
the curve of the output vacuum value from the electric vacuum regulator 20 against
the voltage duty cycle of the electric vacuum regulator. Thus, for any desired output
vacuum, the ECU 26 interprets the map in a ROM and develops the appropriate voltage
duty cycle signal for the electric vacuum regulator 20 to regulate the output vacuum.
[0011] The electric vacuum regulator 20 receives the duty cycle signal and controls the
output vacuum from its output port 18 according to the duty cycle of the signal. This
is accomplished by mixing atmospheric pressure taken from an air pressure source 27
and the vacuum pressure taken from a vacuum source such as the intake manifold 14
of the engine. This is schematically represented by the line from the intake manifold
14 to the input port 28 of the electric vacuum regulator 20. The atmospheric pressure
is provided through an orifice 30 in the regulator to the mixing chamber 32.
[0012] Thus, with the system of Fig. 1, the EGR valve 10 during normal engine operation
is supplied with a variable vacuum signal which causes the EGR valve 10 to open a
known amount and allow a calculated amount of exhaust gas to mix with the air-fuel
mixture. The constant current circuit 34 maintains the current level to the electric
vacuum regulator 20 regardless of resistance changes in the coil due to temperature
or aging or due to fluctuations or changes in the battery voltage.
[0013] The system of Fig. 1 utilizes a positive gain electric vacuum regulator 20 which
is defined as having the vacuum output therefrom increase as the duty cycle increases
to 100%. The positive gain electric vacuum regulator 20 is illustrated in Fig. 2 and
the graph of Fig. 4 illustrates its output characteristics for various adjustments
of the stator means 36.
[0014] If the system of Fig. 1 utilized a negative gain electric vacuum regulator 21, which
is illustrated in Fig. 3, the vacuum switch 24 would be omitted as any failure of
the electric vacuum regulator 21 would affect the operability of the engine enough
to make the engine operator notice that there is a failure. The negative gain electric
vacuum regulator 21 is defined as having the vacuum output therefrom decreasing as
the duty cycle increases to 100%. The graph of Fig. 5 illustrates the output characteristics
of the negative gain electric vacuum regulator 21 for various stator adjustments.
[0015] The failure of an EGR valve 10, independently of the characteristic of the electric
vacuum regulator 20, will in all probability not be noticed by the engine operator
because exhaust gas will not be mixed with the air-fuel mixture, but such failure
will cause emissions from the engine to be changed which may or may not pass environmental
testing.
[0016] The electric vacuum regulator 20 as illustrated in Fig. 2 has a cap 38 having at
least a pair of ports 18 and 28 at one end, one being the input port 28 and the other
the output port 18. The interior of the cap 38 forms a portion of the mixing chamber
32 interconnecting the two ports. Each port 18 and 28 is adapted to receive a vacuum
hose, which is not shown, for connecting the input port 28 to a source of the vacuum
14, and for connecting the output port 18 to the utilization device 16. In the embodiment
of Fig. 2 at the opposite end of the cap 38, there is at least one aperture 40 open
to a source of air pressure 27 or atmospheric pressure.
[0017] Connected to the cap 38 is a bobbin means 42 providing an area to wind an electromagetic
coil 44 therearound and cooperates with the cap 38 to form the remaining portion of
the mixing chamber 32. The bobbin means 42 is enclosed by a shell 46 fabricated from
a magnetizable material. The leads or the ends of the coil are extended to a pair
of terminals which are connected to wires 48 extending outward of the shell 46 for
receiving the electrical control signals.
[0018] At the end of the bobbin means 42, opposite the terminals, a seating means 50 having
a central orifice 30 is retained within the bobbin means 42 in Figure 2. The central
orifice 30 is concentric with the central aperture of the bobbin means 42 which receives
the stator means 36. The stator means 36 is an elongated shaft threaded at one end
to provide an adjustment for positioning the stator means 36 in alignment with the
central orifice 30 of the seating means 50. This adjustment, which may be made by
means of a small hexagonal wrench or similar tool applied to a receptacle 52 in the
end of the stator means 36, affects the operation of electromagnetic circuit as will
hereinafter be described.
[0019] There is positioned across the seating means 50, which is typically cylindrical in
shape, a flat steel disk 54 which is free to move and is constrained only by the walls
of the mixing chamber 32. The mixing chamber 32 interconnects the input port 28 and
the output port 18 providing for the transfer of vacuum therebetween. In a normal
state with no current applied to the coil 44 and no vacuum, the disk 54 rests upon
the seating means 50 encircling the orifice 30. A spring bias means 56 is positioned
so as to bias the disk 54 against the seating means 50.
[0020] Located in the input port 28 upstream of the mixing chamber 32 is a bleed orifice
or restrictor 58 which controls the amount of vacuum flow from the input port 28.
[0021] Adjacent a plurality of apertures 40 in one end of the shell 46 is a filter means
60 which prevents any particles in the air pressure source 27 from getting into the
valve. As is customary in devices of this nature, the filter 60 operates to make sure
that the air that flows within the valve is clean of any particles which would inhibit
or hinder the operation of the valve.
[0022] In Figure 2, once the air from the air pressure source 27 flows through the filter
60, the clean air then flows up through the central aperture 62 of the bobbin means
42. The stator means 36 has a crosshole 64 inclined to its longitudinal axis to provide
for the flow air therethrough. The crosshole 64 is then connected with the longitudinally
extending bore 66 from the middle of the stator means 36 to the top of the stator
means 36. At the end of the stator means 36, this bore 66 is the central orifice 30
for supplying the air pressure source 27 to the mixing chamber 32 of the vacuum regulator
20.
[0023] For the operation of the electric vacuum regulator 20 of Fig. 2, reference is made
to Fig. 4 which shows a series of curves 68-71 illustrating the relationship of the
output vacuum as a percent of the voltage duty cycle of the operation of the coil
44. The onboard computer 26 of Fig. 1 determines the voltage duty cycle desired for
operation of the coil 44 so that the vacuum of the output port 18 is a previously
calculated value. This value enhances the operation of the internal combustion engine
which is controlled in part by the utilization device 10 from the output port 18 of
the EVR 20. When the coil 44 is not energized the position of the steel disk 54 is
determined by the pressure of the air from the air pressure source 27, the spring
force from the spring bias means 56 and the amount of vacuum in the mixing chamber
32. As the onboard computer 26 determines what is necessary for the operation of the
utilization device 10, the duty cycle signal will cause the vacuum regulator 20 to
operate at some percent duty cycle. The curves 68-71 of Fig. 4 indicate that for different
adjustments of the stator means 36 the output vacuum varies with the value of the
duty cycle. The fourth curve 71 indicates that there is a point in the duty cycle
with a particular stator means 36 adjustment when the magnetic force retains the steel
disk 54 against its seating means 50 and the output 18 and input 28 ports are substantially
connected together such that the input and output vacuums are equal.
[0024] With input vacuum applied to the input port 28 in the cap 38 and the output port
18 attached to a utilization device 10, a vacuum will start to build up inside the
valve. This will create a force that will try to lift the disk 54 off the seating
means 50. The spring force of the bias spring 56 will prevent this up to the point
that the vacuum force will overcome it. Then the disk 54 will lift off from the seating
means 50 and atmospheric air will enter through the filter 60. This will reduce the
vacuum force and the spring 56 will push the disk 54 back on the seating means 50.
The vacuum will build up again and the process will be repeated.
[0025] With current applied to the coil 44, a magnetic field will be created in the valve.
This field will pass through the shell 46, the stator means 36 and the disk 54 creating
a magnetic force between the stator means 36 and the disk 54. This force works in
the same direction as the spring force, so increased current will give increased regulated
output vacuum.
[0026] Referring to the negative gain embodiment of Fig. 3, wherein the same reference numerals
are used to identify similar elements as the embodiment of Fig. 2. The difference
in this embodiment is that the vacuum force and the magnetic force from the coil 44
aid each other and work against the force from the spring bias means 56, where in
the embodiment of Fig. 2 the force from the spring bias means 56 and the magnetic
force aid each other and work against the vacuum force.
[0027] In Fig. 3 when the vacuum regulator 21 has no power applied to the coil 44 and no
vacuum, the central orifice 30 from the air pressure source is closed and the input
28 and output ports 18 are connected together. In this particular condition, the spring
bias means 56 holds the disk 54 against the seating means 50 surrounding the central
orifice 30 effectively closing the orifice 30. Inasmuch as the stator means 36 in
this particular embodiment extends into the mixing chamber 32 which is typically at
a vacuum level and not at atmospheric level, a sealing means 72 must be provided along
the stator means 36 to prevent any leakage of air pressure or vacuum from the mixing
chamber 32. As in Fig. 2, the stator means 36 is threadably adjusted, although in
Fig. 3 the bobbin means 42 is tapped to provide the thread adjustment.
[0028] With input vacuum applied to the input port 28 in the cap 39 and the output port
18 attached to a utilization device 10, a vacuum will start to build up inside the
valve 21. This will create a force that will try to lift the disk 54 off the seat
means 50. The spring force of the bias spring 56 will prevent this up to the point
that the vacuum force will overcome it. Then the disk 54 will lift off from the seating
means 50 and atmospheric air will enter through the filter 60. This will reduce the
vacuum force and the spring 56 will push the disk 54 back on the seating means 50.
The vacuum will build up again and the process repeated.
[0029] With current applied to the coil 44, a magnetic field will be created in the valve.
This field will pass through the shell 46, the stator means 36 and the disk 54 creating
a magnetic force between the stator means 36 and the disk 54. This force works against
the spring force, so increased current will give decreased regulated output vacuum.
[0030] In both embodiments, Figs. 2 and 3, the magnetic circuit comprises the shell 46,
the disk 54 and the stator means 36. The coil 44, when supplied with a current, will
generate the magnetic field for the magnetic circuit. It is to be understood in both
the embodiments, that once an EVR is set up and the stator means 36 adjustment is
made, only one of the curves of Fig. 4, or Fig. 5 as the case may be, is applicable
as the stator means 36 is sealed in place.
[0031] As previously mentioned the electric vacuum regulator of the present invention, either
the positive gain embodiment 20 or the negative gain embodiment 21, comprises a steel
disk 54 which functions to separate and seal the vacuum side of the regulator from
the atmospheric side and to complete the magnetic circuit. In each of the embodiments,
the central orifice 30 is surrounded by a seating means 50 which in the preferred
embodiment is brass and non-magnetic and also is virtually wear resistant in this
application. The steel disk 54 seats on the brass seating means 50 sealing the central
orifice 30 supplying air pressure into the mixing chamber 32 of the regulator 20 or
21.
[0032] There has thus been shown and described an electric vacuum regulator responding to
duty cycle pulse electrical signals for regulating the vacuum utilization devices
within predetermined limits. As previously indicated the main or a major application
of such electric vacuum regulators may be found in internal combustion engines for
motor vehicles.
1. An electric vacuum regulator (20) comprising:
an input port (28) adapted to be connected to a vacuum source, said input port having
restrictor (58) coupled thereto;
an output port (18) adapted to be connected to a vacuum utilization device (10);
a mixing chamber (32) interconnecting said input and said output ports;
an orifice (30) for communicating an air pressure source with said chamber;
a disk (54) adapted to seal said orifice for separating the air pressure source from
the vacuum source;
spring means (56) biasing said disk in a closed position against said orifice;
stator means (36) located in alignment with said orifice and spaced from said disk;
a shell (46) enclosing said mixing chamber, orifice, disk, spring means and said stator
means; and
coil means (44) magnetically coupled to said stator means, said shell and said disk
and operative in response to an electrical signal for magnetically attracting said
disk for controlling the mixing of the air from the air pressure source with the vacuum
from said input port and thereby regulating the vacuum at said output port proportional
to the vacuum at said input port.
2. An electric vacuum regulator according to Claim 1 additionally including seating
means (50) encircling said orifice (30) for cooperating with said disk (54) for closing
said orifice.
3. An electric vacuum regulator according to Claim 2 wherein said seating means (50)
is a non magnetic member and said stator means (36), said shell (46) and said disk
(54) are magnetizable members.
4. An electric vacuum regulator according to Claim 2 wherein said stator means (36)
is adjustable for changing the air gap between said stator means and said disk (54)
thereby controlling the vacuum level at said output port (18).
5. An electric vacuum regulator according to Claim 1 additionally including filter
means (60) between the air pressure source and said orifice (30) for filtering out
particles from the air pressure source.
6. A vacuum operated system used on an internal combustion engine for controlling
the operation of the engine, said system comprising:
a source of vacuum (14);
a vacuum utilization device (10) operable in response to a vacuum signal for controlling
the operation of the engine, said device having an input vacuum port (16);
control means (26) for generating a plurality of electrical output vacuum value signals
in response to various engine operating conditions and operable to generate one of
said electrical output vacuum value signals having a duty cycle according to the present
engine operating condition;
a source of pressure; and
an electric vacuum regulator valve (21) connected to said source of vacuum and said
source of pressure and responsive to said electrical signal for generating said vacuum
signal at a regulated vacuum level between said source of vacuum and said source of
pressure according the duty cycle of said electrical signal.
7. A vacuum operated system used on an internal combustion engine for controlling
the operation of the engine, said system comprising:
a source of vacuum (14);
a vacuum utilization device (20) operable in response to a vacuum signal for controlling
the operation of the engine, said device having an input vacuum port (16);
a vacuum switch (24) responding to the vacuum applied to said input port of said device
for indicating the presence of a vacuum level sufficient to operate said device;
control means (26) for generating a plurality of electrical output vacuum value signals
in response to various engine operating conditions and operable in response to said
vacuum switch to generate one of said electrical output vacuum value signals having
a duty cycle according to the present engine operating condition;
a source of pressure; and
an electric vacuum regulator valve (20) connected to said source of vacuum and said
source of pressure and responsive to said electrical signal for generating said vacuum
signal at a regulated vacuum level between said source of vacuum and said source of
pressure according the duty cycle of said electrical signal.