U.S. patent application number 14/867778 was filed with the patent office on 2016-01-21 for sensors and sensor interface systems.
The applicant listed for this patent is Cummins Emission Solutions Inc.. Invention is credited to Daniel R. Harshbarger.
Application Number | 20160018349 14/867778 |
Document ID | / |
Family ID | 48870032 |
Filed Date | 2016-01-21 |
United States Patent
Application |
20160018349 |
Kind Code |
A1 |
Harshbarger; Daniel R. |
January 21, 2016 |
SENSORS AND SENSOR INTERFACE SYSTEMS
Abstract
An apparatus, comprising a housing; a first connector coupled to
the housing and having a first plurality of contacts; a second
connector coupled to the housing and having a second plurality of
contacts; and a circuit electrically connected to at least one of
the first contacts and at least one of the second contacts. The
circuit is encapsulated within the housing. The circuit is
configured to generate an output signal in response to a resistance
sensed at the at least one of the first contacts.
Inventors: |
Harshbarger; Daniel R.;
(Columbus, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Cummins Emission Solutions Inc. |
Columbus |
IN |
US |
|
|
Family ID: |
48870032 |
Appl. No.: |
14/867778 |
Filed: |
September 28, 2015 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13754710 |
Jan 30, 2013 |
9161470 |
|
|
14867778 |
|
|
|
|
61592803 |
Jan 31, 2012 |
|
|
|
Current U.S.
Class: |
324/603 ;
324/691 |
Current CPC
Class: |
F01N 13/008 20130101;
G01N 27/045 20130101; H05K 7/02 20130101; F02D 41/1494 20130101;
F02D 2041/285 20130101; F02D 2400/22 20130101; F02M 1/00 20130101;
F02D 41/222 20130101 |
International
Class: |
G01N 27/04 20060101
G01N027/04 |
Claims
1-6. (canceled)
7. A sensor, comprising: a first housing; a sensor element disposed
in the first housing; a second housing; a conductor coupled to the
first housing and the second housing; a connector coupled to the
second housing, the connector including a contact; a buffer
electrically connected to the sensor element through the conductor;
wherein: the second housing encapsulates the buffer; and the buffer
is electrically connected to the contact of the connector.
8. The sensor of claim 7, wherein at least part of the connector is
part of the second housing.
9. The sensor of claim 7, wherein the conductor is coupled to the
second housing by a strain relief.
10. The sensor of claim 7, wherein the buffer is configured to
generate an output signal in response to a resistance of the sensor
element.
11-14. (canceled)
15. The sensor of claim 7, wherein the sensor element is a
resistive sensor element.
16. The sensor of claim 7, wherein the buffer is a circuit that
includes an input conditioning.
17. The sensor of claim 16, wherein the circuit includes an
amplifier.
18. The sensor of claim 17, wherein the circuit includes a
filter.
19. The sensor of claim 7, wherein the sensor element is a
particulate matter sensor element.
20. A sensor, comprising: a first housing; a resistive sensor
element disposed in the first housing; a second housing; a circuit
encapsulated in the second housing; a conductor coupled to the
first housing and the second housing, wherein the conductor
electrically connects the circuit to the resistive sensor element;
and a connector coupled to the second housing, wherein the
connector includes a contact that is electrically connected to the
circuit
21. The sensor of claim 20, wherein at least part of the connector
is part of the second housing.
22. The sensor of claim 20, wherein the conductor is coupled to the
first housing by a strain relief.
23. The sensor of claim 20, wherein the conductor is coupled to the
second housing by a strain relief.
24. The sensor of claim 20, wherein the buffer is configured to
generate an output signal in response to a resistance of the sensor
element.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a divisional application of U.S.
patent application Ser. No. 13/754,710 filed on Jan. 30, 2013,
which claims the benefit of U.S. Provisional Patent Application
Ser. No. 61/592,803, filed on Jan. 31, 2012, each of which is
incorporated herein by reference
BACKGROUND
[0002] Embodiments relate to sensor systems and, in particular,
interfaces for sensor systems.
[0003] Some sensors can use resistivity to indicate sensed
information. For example, a thermistor can indicate a sensed
temperature through its resistance. A circuit can be used to
measure the resistance. A vehicle can include multiple such
sensors, such as temperature sensors for intake air, exhaust,
coolant, or the like.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] The description herein makes reference to the accompanying
drawings wherein like reference numerals refer to like parts
throughout the several views, and wherein:
[0005] FIG. 1 is a block diagram illustrating a sensor interface
module according to an embodiment.
[0006] FIG. 2 is a block diagram illustrating a sensor interface
module according to another embodiment.
[0007] FIG. 3 is a block diagram illustrating a buffer of a sensor
interface module according to an embodiment.
[0008] FIG. 4 is a block diagram illustrating a sensor according to
an embodiment.
[0009] FIG. 5 is a block diagram illustrating an engine control
system according to an embodiment.
[0010] FIG. 6 is a graph illustrating a variability in sensed
signals without a sensor interface.
[0011] FIG. 7 is a graph illustrating a variability in sensed
signals with a sensor interface according to an embodiment.
[0012] FIG. 8 is a graph illustrating another variability in sensed
signals without a sensor interface.
[0013] FIG. 9 is a graph illustrating another variability in sensed
signals with a sensor interface according to an embodiment.
[0014] FIG. 10 is a block diagram illustrating an engine system
including an after-treatment system according to an embodiment.
DETAILED DESCRIPTION
[0015] Embodiments will be described with reference to the
drawings. Although particular embodiments will be described, the
scope of the following claims is not limited to these embodiments.
In contrast, alterations, modifications, combinations, or the like
can be made.
[0016] FIG. 1 is a block diagram illustrating a sensor interface
module according to an embodiment. In an embodiment, the sensor
interface module 10 includes a housing 12. The housing 12 can be
configured to substantially encapsulate a circuit 14. A first
connector 16 and a second connector 18 are coupled to the housing
12. In an embodiment, the connectors 16 and 18 can be coupled to
the housing 12 by wires or other conductors. In another embodiment,
the connectors can include connector housings that are integrally
formed with the housing 12. In another embodiment, the connectors
16 and 18 can include connector housings that are mechanically
attached to the housing 12. The connectors 16 and 18 can be coupled
to the housing 12 using any combination of such techniques or
similar techniques.
[0017] The connectors 16 and 18 can each include a plurality of
contacts. The connectors 16 and 18 can have a same or different
number of contacts. The circuit is electrically connected to at
least one of the contacts of the first connector 16 and at least
one of the contacts of the second connector 18. Connections 20 and
22 represent connections between the contacts of the connectors 16
and 18 and the circuit 14.
[0018] In an embodiment, the circuit 14 can be configured to
generate an output signal in response to a sensed resistance. The
circuit 14 can be coupled to one or more contacts of the first
connector 18. Through the first connector 18, the circuit 14 can be
coupled to a sensor and, in particular, a resistance based sensor.
For example, the first connector 18 can include two contacts that
are coupled to the sensor. A resistance sensed between the two
contacts can be interpreted as a signal from the sensor. The
circuit 14 can be configured to generate the output signal based on
the sensed resistance. Although two contacts have been described,
any number of contacts can be used to sense the resistance. For
example, a single contact can be used with a node common to the
circuit 14 and the sensor. In another example, the sensor can
include a bridge circuit with multiple associated contacts. The
circuit 14 can be coupled to contacts of the first connector 18 to
supply a bias voltage, sense an output voltage, or the like.
[0019] FIG. 2 is a block diagram illustrating a sensor interface
module according to another embodiment. In an embodiment, multiple
connections can terminate and/or pass through the housing 12. For
example, as will be described in further detail below, the second
connector 38 can be coupled to a control module. Through the
connector 38, a power connection 34 can be supplied. In addition, a
common node, such as a ground 46 can be supplied.
[0020] Furthermore, one or more connections between the connectors
36 and 38 can be made. For example, a particulate matter sensor can
include a heater configured to regenerate the sensor. The
connections 40 and 44 can be pass-through connections for such a
heater connection. However, in another embodiment, a common node
can be shared among a pass-through connection, the sensor, the
circuit, a power supply, a combination of such connections, or the
like.
[0021] In an embodiment, a connection to a sensor includes
connections 20 and 42. For example, connection 20 can be used for a
sensor signal. Connection 42 can be a common node coupled to a
common node 46 of connector 38. In another embodiment, connection
42 can be another sensor node, for example, of a differential pair.
The module 30 can include any such connections, common nodes,
pass-through connections, or the like.
[0022] In an embodiment, the connection 40 can be a direct
connection. For example, a wire can be directly connected to
contacts of the connectors 36 and 38. However, the connection 40
can be formed in other ways. For example, the connection 40 can
include a part of the circuit 32. The connectors 36 and 38 can be
soldered to a trace on a circuit board of the circuit 32.
[0023] In an embodiment, a number of contacts of the first
connector 36 can be different from a number of contacts. As
described above, each of the first connector 36 and second
connector 38 can include multiple contacts. However, all of the
contacts of the second connector 38 may not be used in the first
connector 36. For example, the first connector 36 can have four
contacts, two for a sensor input and return, 20 and 42, and two for
a heater of the sensor, 40 and 44. The second connector 38 can have
two contacts for a heater of the sensor, 40 and 44, an output
signal 22, and power supply connections 34 and 46.
[0024] In an embodiment, the connectors 36 and 38 can be opposite
gender connectors. As will be described below, the module 30 can be
used in a vehicle control system. By using the same connector with
opposite genders, the module 30 can be placed in line with an
existing sensor connection. Power, other signals, other controls,
or the like can be transferred to the circuit 32 through the
connector 38, a third connector 48, or the like. Accordingly,
existing control systems having a sensor connection that has
degraded or has the potential to degrade can be retrofit with the
module 30, making the sensing system more tolerant of variations
and extending the useful life.
[0025] FIG. 3 is a block diagram illustrating a circuit of a sensor
interface module according to an embodiment. In this embodiment, a
first connector 62 can be configured to be coupled to a sensor. For
example, the first connector 62 can be a connector configured to
mate with a corresponding connector of a sensor. The circuit 60 can
include a sensor bias circuit 64 associated with a target sensor.
For example, the sensor bias circuit 64 can include a pull-up
resistor to create a resistive divider with a resistive sensor. In
another example, the sensor bias circuit 64 can include a bridge
circuit. Any bias or interface circuit can be used as appropriate
to the target sensor.
[0026] The circuit 60 can include input conditioning 66. For
example, the input conditioning 66 can include over-voltage
protection, reverse voltage protection, short circuit protection,
or the like. In addition, the input conditioning 66 can include
input offset mitigation circuitry.
[0027] The circuit 60 can include an amplifier 68. The amplifier 68
can be configured to scale, level-shift, limit, perform a
combination of such functions, or the like. In an embodiment, the
amplifier 68 can include a relatively low impedance output. Thus,
for a resistivity based sensor, variability in connectors, wiring,
or the like that can add parasitic resistance will likely be higher
than the output impedance of the amplifier 68. Such parasitic
effects will have a reduced effect on an output sensor signal.
[0028] In an embodiment, the circuit 60 can include filter 70. For
example, the filter 70 can be a low pass filter; however, in other
embodiments, the filter 70 can be a high-pass, band-pass, all-pass,
notch filter, or the like according to the sensed signal and/or
desired characteristics of the signal.
[0029] Although illustrated as discrete blocks with individual
connections, the function of the various circuitry of the circuit
60 could be combined, distributed, or the like. For example, the
sensor bias 64, input conditioning 66, amplifier 68, and filter 70
can be combined together into an aggregate amplifier circuit.
[0030] FIG. 4 is a block diagram illustrating a sensor according to
an embodiment. In this embodiment, a sensor 90 is disposed with a
sensor element 94 in fluid communication with a channel 98. For
example, the channel 98 can be part of an exhaust system of a
vehicle. The sensor element 94 can include a resistivity based
particulate matter sensor. The sensor element 94 can be disposed at
least in part in a housing 92.
[0031] A circuit 100 can be disposed in a second housing 102. In
particular, the circuit 100 can be substantially encapsulated in
the second housing 102. A connector 104 can be coupled to the
second housing 102. The connector 104 can be coupled to the second
housing 102 similar to connector/housing couplings described above.
For example, the second housing 102 can be a separate housing or
part of a housing of the connector 104. A conductor 96 is coupled
to the housings 92 and 102. The circuit 102 is electrically
connected to the sensor element 94 through the conductor 96.
[0032] The conductor 96 can be coupled to the housings 92 and/or
102 in a variety of ways. For example, the conductor 96 can be
coupled to a housing 92 and/or 102 through a strain relief such as
a resin, a clamp, a boot, a strap, or the like. In an embodiment,
no connectors are present between the sensor element 94 and the
circuit 100.
[0033] The circuit 100 can be configured to generate an output
signal based on the sensor element 94 in response to a signal
received through the conductor 96. For example, as described above,
the sensor element 94 can be a resistive sensor element. The
circuit 100 can be configured to sense a resistance of the sensor
element 94 and generate an output signal accordingly.
[0034] Although one conductor 96 has been described, any number of
conductors can be used as desired. Any input or output associated
with the sensor element 94, associated components, or the like can
include associated conductors. For example, as described above, two
conductors can be associated with a heater for the sensor element
94 and two conductors can be associated with the sensor element 94
itself. In another example, any connection through a first
connector 16, 36, or the like described above can be routed from
the first housing 92 to the second housing 102 without intervening
connectors.
[0035] In an embodiment, the sensor 90 can be used to retrofit
existing installed sensors. For example, the connector 104 can be
configured to have substantially the same configuration as a sensor
to be replaced. If additional connections, such as a connector for
power and or other signals is desired, a connector similar to
connector 48 described above can be used.
[0036] Although a particulate matter sensor has been used as an
example, other types of sensors can be used with the circuit 100.
Any sensor with a relatively high resistivity can be used with the
circuit 100. For example, the sensor can include a pressure sensor
configured to sense a pressure due to small resistance changes in
material with a relatively large quiescent magnitude. In another
example, the sensor can include a thermistor with a relatively high
resistance for an expected temperature in operation.
[0037] FIG. 5 is a block diagram illustrating an engine control
system according to an embodiment. In this embodiment, the control
system 120 includes a sensor 124 having a cable 126 and a connector
128. The sensor is disposed in fluid communication with channel
122. As described above, the channel 122 can be an exhaust system
of the engine 150 and the sensor 124 can be a particulate matter
sensor.
[0038] A sensor interface module 130 can include connectors 132 and
134. The module 130 can be coupled to the sensor 124 through the
connectors 128 and 132. In a particular embodiment, the connectors
128 and 132 can be directly connected. Thus, only a single
connector pair is disposed between the sensor element 125 and a
circuit of the module 130.
[0039] The module 130 is coupled to a control module 148 through
wiring harness 140. The harness 140 can include multiple
connectors. Connectors 136 and 138 are illustrated with examples of
optional intervening connectors 144 and 142 illustrated in phantom.
Any number of connector pairs can be present between the module 130
and control module 148. The control module 148 includes a connector
146 coupled to the connector 138 of the wiring harness 140.
[0040] The control module 148 can be coupled to an engine 150. For
example, the control module 148 can be part of an engine management
system. Control signals to and from the module 130 and/or other
components can be processed by the control module 148. The control
module 148 can be any variety of devices. For example, the control
module 148 can be a dedicated controller configured to solely
interact with the sensor 124. The control module 148 can have a
communication interface such as a CAN bus interface to communicate
with other control systems. In another example, the control module
148 can be an emission control computer of a vehicle. In another
example, the control module 148 can be a controller for the entire
vehicle including other non-emission related subsystems.
[0041] The module 130 can include a circuit, such as the circuit
14, 32, 60, or the like as described above. Accordingly, an effect
of intervening connectors of the wiring harness 140 can have a
reduced effect on a quality of the signal from the sensor 124.
[0042] In an embodiment, the module 130 can be configured to output
a signal capable of driving an input of the control module 148 that
is configured to expect an input from the sensor 124. For example,
the control module 148 can have bias circuitry for biasing the
sensor 124 if the module 130 was not installed. The module 130 can
be configured to drive such an input. That is, even if a control
module 148 is configured to be directly electrically coupled to a
sensor 124, the module 130 can accommodate any such circuitry on
the input of the control module 148 and/or emulate the sensor
124.
[0043] In another embodiment, the control module 148 can have
reduced circuitry for processing an input from the sensor 124. For
example, the module 130 can include a lower output impedance
circuit. Accordingly, requirements for input offset currents and
voltages associated with the control module 148 can be loosened.
That is, the control module 148 can be designed with a greater
variability and/or magnitude of input offset currents and voltages.
For example, cost constraints, materials, and/or other design and
manufacturing decisions can result in a control module 148 that has
input characteristics that can make a connection to a high
resistivity sensor difficult if not inoperable. The module 130 can
allow such lower cost designs to be operable by increasing
tolerance of such input offset effects.
[0044] In an embodiment, the output of the module 130 can be a
signal that is similar to a signal output by the sensor 124. For
example, a signal from the sensor 124 can be an analog signal.
Similarly, the module 130 can be configured to output a
corresponding analog signal. That is, the signal that is
transmitted to the control module 148 can be an analog signal. In a
particular embodiment, the signal is not digitized, packetized, or
otherwise digitally processed; however, such functions,
transformations, or the like can occur in the control module 148 or
other similar circuitry.
[0045] As described above, the channel 122 can be part of an
exhaust system. Accordingly, the sensor 124 can be exposed to
relatively high heat. Some circuitry may not operate under such
conditions. By placing the module 130 offset from the sensor 124
due to the cable 126, a reliability of the system 120 can be
improved.
[0046] FIG. 6 is a graph illustrating a variability in sensed
signals without a sensor interface. Graph 170 illustrates a
variability of output signals for two systems due to variability in
components, operating conditions, and the like. Axis 178 represents
a frequency of occurrence and axis 179 is an output level. Curve
172 represents a variability with ideal interconnects between a
sensor and a controller, such as the sensor 124 and control module
148 of FIG. 5, but without the module 130.
[0047] In a particular example, a resistivity based sensor can have
a substantially open circuit when no material is sensed. To
distinguish between a clean sensor and a disconnected sensor, a
resistor can be placed in parallel with the sensor. Thus, even when
the sensor is a substantially open circuit, the resistance of the
parallel resistor can be sensed. Curve 172 represents such a
configuration with variability in the parallel resistor,
components, or the like with ideal interconnections.
[0048] Curve 174 represents a variability considering the effect of
interconnections between the sensor and a controller yet
disconnected from a sensor. In an embodiment, connectors of wire
harnesses can add parallel resistances. When a sufficient number of
such parallel resistances are combined, the effective resistance
can approach that of the intentionally added parallel resistance.
Curve 174 represents such parasitic effects but with the sensor
disconnected.
[0049] As illustrated curve 172 overlaps curve 174 in region 176.
That is, a connected sensor cannot be distinguished from an
unconnected sensor over the variability of components and
conditions.
[0050] For example, a number of connector pairs can connect the
sensor to the control module. Assuming that a connector can
introduce a 100 M.OMEGA. resistance between terminals, with four
connector pairs, eight 100 M.OMEGA. parasitic resistances are
connected in parallel, resulting in approximately 12.5 M.OMEGA.
parallel resistance. Such a resistance could be present even if the
sensor is not connected.
[0051] A 10 M.OMEGA. open circuit detection resistor can be used.
Accordingly, the parallel parasitic resistance can mask the
intended parallel resistance. That is, as illustrated in FIG. 6, a
variability of the parallel resistance can overlap with the
parasitic parallel resistance. In this example, the minimum
parallel parasitic resistance in normal operations can be
represented by a lower end of the curve 174. Although the open
circuit detection resistor can have a nominal value of 10 M.OMEGA.,
the resistance could vary over particular operating conditions and
component variability to be greater than 12.5 M.OMEGA.. To increase
the lower limit of the parallel parasitic resistance, a number of
connections can be reduced; however, this can place an upper limit
on connections for a sensor.
[0052] FIG. 7 is a graph illustrating a variability in sensed
signals with a sensor interface according to an embodiment. Similar
to FIG. 6, graph 180 illustrates the variably with axis 188
representing occurrence and axis 189 representing the output level.
In this example, a module such as the module 130 described above is
used. Curve 182 represents the sensor with a parallel resistivity.
Curve 184 represents a disconnected sensor.
[0053] In particular, a gap 186 is introduced. A threshold can be
established to decide whether the sensed value indicates a
connected or disconnected sensor. Since less parasitic components
are disposed between a sensor and module, an effect on the output
of the module by the parasitic components is reduced. Furthermore,
the lower impedance output of a module can reduce an effect of
subsequent parasitic components.
[0054] In an embodiment, the module 130 can aid in diagnosing
problems in a sensor system. For example, a megaohm meter may be
needed to measure the sensor resistance if it is directly. In
addition the sensor wiring may need to be checked to determine if a
particular resistance measurement is due to deteriorated wiring.
With the module 130 or similar modules, a measurement can be made
at the output of the module 130 reducing a need for a megaohm meter
and the parasitic resistance of sensor wiring need not be measured
as the output of the module 130 can tolerate parasitic resistances
that may require a megaohm meter to diagnose.
[0055] FIG. 8 is a graph illustrating another variability in sensed
signals without a sensor interface. Graph 190 again represents an
occurrence axis 198 versus an output axis 199. Curve 192 represents
a system without a module, and an example of variability
considering worst case conditions. Curve 194 represents an example
considering ideal conditions. Note that in this case, the sensor is
connected for both curves. Total width 196 corresponds to a
potential variability in the output from ideal to worst case
conditions.
[0056] FIG. 9 is a graph illustrating another variability in sensed
signals with a sensor interface according to an embodiment. Graph
200 again represents an occurrence axis 208 versus an output level
axis 209. Curve 202 represents an example of worst case conditions
while curve 204 represents an example of ideal conditions. However,
in contrast to FIG. 8, a module as described above is present.
Accordingly, not only is a variability within ideal conditions
reduced, but a variability between worst case and ideal conditions
is reduced.
[0057] FIG. 10 is a block diagram illustrating an engine system
including an after-treatment system according to an embodiment. In
this embodiment, the engine system 220 includes an engine 222
coupled to a particulate matter filter 226 through an exhaust
channel 224. The particulate matter filter 226 can be coupled to a
catalyst system 230 through channel 228. For example, the catalyst
system 230 can include a diesel exhaust fluid system and a
selective catalyst reduction system. However, other types of
catalyst systems can be used.
[0058] A sensor 248 is disposed in channel 228. The sensor 248 is
coupled to a sensor interface 234 through cable 246 and connectors
242 and 244. The connection between the sensor 248 and sensor
interface 234 can be as described above. Thus, the sensor signal
236 can be provided to the control module 238 and be in control of
the engine 240. Accordingly, the reliability of the system 220 can
be improved.
[0059] Although the sensor 248 is illustrated as coupled to channel
228, the sensor 248 can be coupled to other locations upstream or
downstream of the particulate matter filter 226. For example, the
sensor 248 could be coupled to channel 232 downstream of the
catalyst system 230, or other downstream component. In another
example, the sensor 248 could be coupled to the channel 224,
upstream of the particulate matter filter 226. Moreover, multiple
such sensors 248 can be present in the system in various locations,
each with a corresponding circuit as described above.
[0060] While embodiments have been described with reference to the
drawings, the sprit and scope of the following claims is not
limited to the disclosed embodiments, but on the contrary, is
intended to cover various modifications, combinations, and
equivalent arrangements. In reading the claims it is intended that
when words such as "a," "an," "at least one" and "at least a
portion" are used, there is no intention to limit the claim to only
one item unless specifically stated to the contrary in the claim.
Further, when the language "at least a portion" and/or "a portion"
is used the item may include a portion and/or the entire item
unless specifically stated to the contrary.
* * * * *