TECHNICAL FIELD
[0001] The present relation relates to a method for estimating a leakage area in a vehicle
tank assembly according to the preamble of claim 1 and to a method of estimating a
performance from a plurality of pump assemblies and/or at least one pump assembly
at different time periods according to the preamble of claim 25.
BACKGROUND OF THE INVENTION
[0002] Vehicles, for example cars, are generally equipped with at least one vehicle tank
assembly comprising a tank adapted for storing a fluid, for example fuel for powering
the vehicle. Furthermore, the vehicle tank assembly generally comprises a connector
by which a content of the tank may be supplied to a receiving part of the vehicle.
If the tank is adapted for storing fuel, an internal combustion engine of the vehicle
is generally supplied with the fuel through the aforementioned connector.
[0003] As in the case of fuel, the fluid stored in the tank may be volatile, hence a leak
in the vehicle tank assembly at a location above the actual fluid level may result
in that evaporated fluid may exit the tank assembly and enter the surrounding atmosphere.
If the evaporated fluid comprises noxious particles, such as hydrocarbons, the evaporated
fluid may be harmful both to the environment in the vicinity of the vehicle tank assembly,
as well as to the global environment.
[0004] As such, there is a need to test vehicle tank assemblies for leakage on a regular
basis. In fact, in some countries, there are discussions about introducing legislation
stating that a new vehicle should be equipped with systems capable of determining
gas leakages having an area larger than a predetermined value. Preferably, the leakage
test can be performed with equipment provided with the vehicle itself, i.e. a leakage
test can be performed without having to visit a service facility or similar.
[0005] Prior art teaches the use of several leakage testing methods, but they generally
require a large amount of measurement test results and generally only determine if
a leakage is present or not, based on comparing the test results with empirically
obtained reference values. Prior art further teaches that the initial gas volume of
the vehicle tank assembly, being the total volume of the tank assembly minus the volume
of the liquid stored within the tank assembly, has to be known prior to performing
a leakage test. Determining the initial gas volume requires additional metering devices
which may be required to provide results with an accuracy which is similar to the
accuracy of the rest of the leakage test equipment. As such, a regular tank gauge
may not be sufficiently accurate and thus there may be a need for introducing additional
expensive metering devices in the vehicle tank assembly.
SUMMARY OF THE INVENTION
[0007] The object of the invention is to provide a method for estimating a performance of
a pump assembly as a function of the applied pump electrical current, wherein differences
between different pumps of the same model and/or aging of a pump are accounted for.
[0008] This object is achieved by a performance estimating function defined in the attached
claim.
[0009] Thus, the invention relates to a method of estimating a performance from a plurality
of pump assemblies and/or at least one pump assembly at different time periods. Each
pump assembly comprises a gas pump, wherein the performance is indicative of at least
a gas mass flow through the gas pump. Furthermore, each pump assembly comprises a
reference opening and a gas valve for controlling the gas mass flow, the valve being
operable to guide the gas mass flow at least either through the reference opening
or through an outlet opening. The gas pump is supplied with electrical power. According
to the invention, the method comprises the steps of:
- for each of the plurality of pump assemblies and/or the at least one pump assembly
at different time periods:
o measuring the performance for a plurality of applied pump electrical currents;
o estimating the performance by the applied pump electrical current and thereby determining
performance coefficients for a performance function;
∘ operating the valve in order to guide the flow through the reference opening and
determining the corresponding pump reference electrical current,
- for each performance coefficient, generating a performance coefficient function, which
is dependent on at least the pump reference electrical current.
[0010] A further embodiment of the inventive performance testing method further comprises
the steps of:
[0011] Another embodiment of the inventive performance testing method further comprises
the step of:
[0012] A further embodiment of the inventive performance testing method further comprises
the step of estimating each of the performance functions by an affine performance
function.
[0013] Another embodiment of the inventive performance testing method further comprises
the step of estimating the coefficients to each of the affine performance functions
by utilizing a least-squares method.
[0014] A further embodiment of the inventive performance testing method further comprises
the step of estimating the coefficients to each of the affine performance functions
by utilizing a recursive least-squares method.
[0015] In a further embodiment of the inventive method of performance testing, the pump
assembly forms a part of a vehicle tank assembly, the pump assembly being in fluid
communication with the rest of the tank assembly and the pump assembly performance
comprises a resulting change in pressure in the tank assembly.
[0016] Thus, by utilizing the obtained performance coefficient function as previously described,
an output, comprising the gas mass flow through the pump, from a pump assembly may
be estimated. A method of estimating the output, based on the performance coefficient
function, comprises the steps of:
- operating the valve in order to guide the flow through the reference opening and determining
a corresponding pump reference electrical current,
- determining the performance coefficients, based on the pump reference electrical current,
- operating the valve in order to guide the flow through the outlet opening;
- determining the applied pump electrical current, and
- calculating the output, by utilizing the performance function with the performance
coefficients, utilizing the applied pump electrical current as input to the performance
function.
[0017] One embodiment of the output estimation method preferably further comprises the steps
of:
- operating the valve in order to guide the flow through the outlet opening and determining
a corresponding initial pump minimum electrical current, and
- determining the performance coefficients, based on the initial corresponding pump
minimum electrical current.
[0018] Still another embodiment of the output estimation method preferably further comprises
the steps of:
- determining an pump electrical voltage;
- determining said performance coefficients, based on the pump electrical voltage.
[0019] The output estimated may preferably comprise a change in pressure in a tank assembly
if such a tank assembly is in fluid communication with the pump assembly.
[0020] Advantages of different embodiments of the performance testing method are similar
to the advantages presented when previously discussing methods for estimating the
performance of a gas pump as a function of supplied pump electrical current in conjunction
with the leakage area estimation method, and are thus not presented here.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The present invention will hereinafter be further explained by means of non-limiting
examples with reference to the appended figures wherein;
- Fig. 1
- is schematic view of a vehicle tank assembly on which the method of the invention
may be applied;
- Fig. 2
- is schematic view of an alternative vehicle tank assembly on which embodiments of
the inventive method may be applied, and
- Fig. 3
- is a time history diagram of an electrical current supplied to a gas pump.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0022] Fig. 1 illustrates a vehicle tank assembly 10 on which at least the leakage area
estimation method of the invention may preferably be applied. The tank assembly 10
comprises a tank 12 which is adapted to store a liquid 14, such as fuel. Due to e.g.
improper handling of the vehicle tank assembly, the tank assembly 10, above a liquid
level 16, may be provided with a leakage opening 18 having a leakage area A
leak. It has been observed that one frequent location of the leakage opening 18 is in
the vicinity of a filler cap 22. Thus, evaporated liquid from the stored liquid 14
may exit the tank assembly 10 and enter the surrounding atmosphere.
[0023] The tank assembly 10 optionally comprises a canister 24 in fluid communication with
the tank 12. Furthermore, the tank assembly preferably comprises a gas pump 26. However,
in some implementations of the tank assembly 10 on which the method of the invention
is preferably applied, the gas pump 26 may preferably be replaced by other gas pressurising
means, for example a gas tank having an initial gas pressure which is different than
the initial pressure in the rest of the tank assembly 10. The gas pump 26 is preferably
adapted to provide a gas mass flow into, or out of, the tank assembly 10. The tank
assembly 10 preferably comprises metering means for determining e.g. a pressure in
the tank assembly. In the tank assembly 10 illustrated in Fig. 1, the metering means
comprises a pressure gauge 30 within the tank assembly 10, but the metering means
may be constituted by other gauges, and in some implementations of the tank assembly
10, additional physical properties may preferably be measured, such as a gas mass
flow through the gas pump and the temperature within and/or outside of the tank assembly
10.
[0024] The following relates to a method for estimating the leakage area in a vehicle tank
assembly 10 by varying the pressure in the tank assembly by applying the gas mass
flow through the gas pump 26 during an area estimation time period.
[0025] The method further comprises the steps of establishing an instantaneous gas mass
flow relation of the gas in the tank assembly 10 in which relation the leakage area
Aleak is an unknown parameter. The aforesaid establishment is performed for each of a plurality
of time instants during the area estimation time period, hence a plurality of gas
mass flow relations are obtained. The method further comprises the step of estimating
the leakage area
Aleak by utilizing the instantaneous gas mass flow relations.
[0026] It should be realized that the method may be carried out by either increasing or
decreasing the pressure within the tank assembly 10. Furthermore, in the leakage area
testing methods disclosed herein, the gas pumped by utilizing the gas pump 26 is preferably
air.
[0027] According to a further embodiment, estimation of the leakage area
Aleak is executed by arranging the instantaneous gas mass flow relation of the gas in an
equations system and determining the leakage area
Aleak by utilizing a least-squares method. Preferably, the arrangement of the gas mass
flow relation of the gas is solved by utilizing a recursive least-squares method.
[0028] In a further embodiment, each of the instantaneous gas mass flow relation is an equality
based on an ideal gas law. The ideal gas law stipulates that:
where:
p is the pressure (Pa);
V is the volume (m3);
n is the number of moles of gas;
R is the gas constant J/(mol·K), and
T is the temperature (K).
[0029] The number of moles of gas is equal to the mass of the gas, divided by the molar
mass of the gas:
where:
m is the mass of the gas, and
M is the molar mass of the gas.
[0030] Inserting Eq. 2 into Eq. 1, the following expression is obtained:
where:
r is the specific gas constant. For example, the specific gas constant r for air is
approximately 287 J /(kg · K).
[0031] As a starting point for the aforementioned embodiment, an initial state of the gas
filled portion of the tank assembly is considered. Thus, at a selected starting time
t0 for starting the leakage area estimation method, the following relation is assumed
to apply between the pressure (
p0), volume (
V0) and mass (
m0) of the gas initially entrapped in the tank assembly:
[0032] By applying a gas mass flow
qpump to (or from) the tank assembly 10, the gas mass within the tank assembly 10 may vary.
Thus, the pressure within the tank assembly 10 may also vary. Thus, utilizing the
expression in Eq. 4 for a specific time instant
t after the starting time to, the following expression is assumed to apply:
where:
- Δp(t)
- is a change in pressure;
- ΔV(t)
- is a change in volume of the vehicle tank assembly, due to e.g. elasticity of one
or more components of the tank assembly;
- Δm(t)
- is a change in mass;
- qpump (t)
- is a flow of the gas pump of the system, and
- qleak (t)
- is a flow through the possible leakage opening.
[0033] In Eq. 5 above, it is assumed that the only gas mass flows to the tank assembly 10
are from the gas pump 26 and the leakage 18. However, in embodiments of the method
which are presented hereinbelow, additional flows may be taken into account.
[0034] Combining Eq. 4 and Eq. 5 and utilizing that p(t) =
p0 + Δ
p(
t), the following expression is obtained:
which may be re-arranged to:
[0035] Thus, a first side and a second side of the equality are obtained. The equality is
assumed to be valid for each time instant during the area estimation time period.
[0036] As may be gleaned from Eq. 7, a first side of the equality comprises a first entity
minus a second entity. The first entity comprises a product of: a change of pressure
Δ
p in the tank assembly 10 from the start of the area estimation time period to the
time instant
t, and the initial gas volume
V0 of the tank assembly 10. Furthermore, the second entity comprises a product of: the
accumulated leakage flow
qleak through the leakage 18 multiplied by a temperature T of the gas in the tank assembly
during a time period from the start of the area estimation time period
t0 to the time instant
t; and the specific gas constant r of the gas, wherein in which leakage flow
qleak, the leakage area A
leak is an unknown parameter.
[0037] Furthermore, the leakage flow
qleak may in one embodiment be determined by a leakage measure, wherein the leakage measure
is a product of: the unknown leakage area A
leak and the value of a leakage function
fleak, wherein the leakage function
fleak is a function of at least the pressure p in the tank assembly 10, such as:
[0038] In the following description, the leakage function
fleak is denoted as a function of only the pressure p in the tank assembly 10, pursuant
to Eq. 8, in order to save space. It should however be noted that whenever the leakage
function is used hereinbelow, the function
fleak may preferably further be a function of the pressure of the surrounding medium and/or
of the temperature of the gas in the tank and/or the temperature of the surrounding
medium, i.e.
[0039] Additionally, as may be appreciated from Eq. 7, a second side of the equality may
comprise a third entity, wherein the third entity comprises a product of: the accumulated
gas mass flow
qpump from the gas pump 26 multiplied by the temperature
T of the gas in the tank assembly 10 during a time period from the start of the area
estimation time period
t0 to the time instant
t and the specific gas constant
r of the gas.
[0040] As may be gleaned from Eq. 7, the second side of the equality comprises a term which
relates to a change in volume of the tank assembly 10. In some applications of the
inventive method, in which the tank assembly is considered to be rigid, it may be
a sufficiently good approximation to assume that the change in volume is negligible
and hence set to zero. However, in a further embodiment of the invention, the change
in volume may be considered, such that the second side of the equality may comprise
a fourth entity, subtracted from said third entity, wherein the fourth entity comprises
a product of: the pressure
p in the tank assembly 10 at the time instant
t and a change in volume
ΔV of the tank assembly from the start of the area estimation time period
t0 to the time instant
t.
[0041] In a preferred embodiment of the method, the change in volume Δ
V is modelled as a function of the gas temperature and pressure, i.e.
[0042] The abovementioned volume change function may be empirically determined, for instance
obtained by pressurizing the tank system for a plurality of different pressures and
temperatures and measuring the change in volume. Optionally, the change in volume
for a plurality of different pressures and temperatures may be obtained by structural
analyzes, such as FE analyses, of the tank system. Irrespective of how the change
in volume as a function of pressure and temperature has been determined, i.e. by experiments
or analyses, the results are preferably tabulated and stored in a storage unit. During
the area estimation method, the change in volume for an actual pressure and temperature
may be obtained by utilizing an interpolation method on the aforementioned tabulated
data.
[0044] Thus, what is obtained in Eq. 12 is a gas equality which is valid for a time instant
during the area estimation time period, wherein
t ∈ [
t0 tend]. The gas equality of Eq. 12 is further in a form, suitable for generating an equations
system such as:
[0045] As may be appreciated when studying Eq. 16, an equation system may be obtained if
tend > t0 and an over determined equation system may be obtained if the number of rows in the
equations system is more than two. Thus, the parameter θ, comprising the sought leakage
area
Aleak, can be determined using conventional techniques, such as a least-squares method.
However, as previously mentioned, in a preferred embodiment, a recursive least-squares
method is used.
[0046] In a preferred embodiment a fifth entity is added to the first side of the equality,
wherein the fifth entity comprises a product of: an accumulated gas mass flow
qcanister from the canister 24 multiplied by the temperature
T of the gas in the tank assembly 10 during a time period from the start of the area
estimation time period
t0 to the time instant
t; and the specific gas constant
r of the gas. Thus, the first side of the equality may be re-written as:
[0047] In a further embodiment of the method and as may gleaned from Eq. 17, a sixth entity
is added to the first side of the equality, wherein the sixth entity is representative
of a pressure change due to evaporation of the liquid and/or dewing of the gas in
the tank assembly during a time period from the start of the area estimation time
period
t0 to the time instant
t. In Eq. 16 the pressure change is formulated as an additional gas mass flow
qevapor.
[0048] In order to simplify the analyses of measured data, as well as the data measurements,
the gas temperature
T in the tank assembly 10 is assumed to be constant throughout the area estimation
time period. Thus, Eq. 12 and 13 may be rewritten as:
[0049] Consequently, when a canister 24 is present and/or if evaporation is taken into account,
Eq. 17 may be re-written as:
[0050] The gas pump 26 of the tank assembly 10 is generally supplied with electrical power.
Thus, each of the change in pressure
Δp and the gas mass flow
qpump through the gas pump 26, respectively, is in one preferred embodiment of the method
estimated by a performance function of an applied pump electrical current
l. Each performance function has a set of performance coefficients. Thus, an estimate
of the gas mass flow
qpump through the gas pump 26 may the written as:
where:
- k(·)
- is the performance function.
[0051] Herein, the gas mass flow
qpump is used as an example in the description of the performance estimation portion of
the preferred embodiment of the method. It should however be realized that the description
is equally valid for the change in pressure Δ
p.
[0052] A plurality of different functions are suitable for utilizing as the performance
function. However, in a preferred embodiment of the invention each, of the performance
functions is estimated by an affine performance function. Thus, for the aforementioned
estimate of the gas mass flow
qpump through the gas pump 26, the following expression may be applied:
where:
- α0, α1
- are the performance coefficients of the affine performance function.
[0053] The electrical power is supplied to the gas pump 26 at a predetermined voltage
U. The performance of the gas pump 26 may differ for separate voltages
U applied. Thus, in a preferred embodiment, the performance coefficients of each of
the affine performance functions are dependent on at least the voltage
U supplied to the gas pump 26, such as
where:
- U
- is the applied voltage.
[0054] In order to further enhance the estimate of the performance of the gas pump 26, a
specific pump assembly 34, as illustrated in Fig. 2, may be used used. As may be gleaned
from Fig. 2, the pump assembly 34 comprises a reference opening 36 and a valve 38
for controlling the gas mass flow
pump. The valve 38 is operable to guide the gas mass flow
qpump at least either through the reference opening 36 or to an outlet opening 40 which
outlet opening 40 may be in fluid communication with the tank assembly 10. The pump
assembly 34 of Fig. 2 further comprises an inlet opening 42 which in some implementations
of the pump assembly 34 may be in fluid communication with the surrounding atmosphere.
The cross-sectional area of the reference opening 36 is preferably relatively small
and is preferably less than 0.5 mm
2, more preferably less than 0.2 mm
2. Purely by way of example, the reference opening 36 may be a cylindrical opening
having a diameter of 0.5 mm.
[0055] Utilizing a tank assembly 10, comprising a pump assembly 34 as previously described
with reference to Fig. 2, introduction of additional steps in preferred embodiments
of the method is enabled. As such, according to a preferred implementation of the
performance estimation, the performance coefficients of the performance functions
are established by a coefficient estimation method comprising the step of operating
the valve 38 in order to guide the gas mass flow
qpump through the reference opening 36 and determining a corresponding pump reference electrical
current
lref and determining the performance coefficients of each of the performance functions
depending on the corresponding pump reference electrical current
lref. As such, in the aforementioned example where the gas mass flow
qpump through the gas pump 26 is estimated by an affine performance function, dependent
on at least the supplied voltage
U, the following expression may be obtained:
[0056] The performance estimation may be even further refined by a coefficient estimation
method which comprises the step of operating the valve 38 in order to guide the flow
qpump to the tank assembly 10 and determining an initial corresponding pump minimum electrical
current
Imin, and determining the performance coefficients of each of the performance functions
depending on the corresponding pump minimum electrical current
lmin.
[0057] Again, utilizing the aforementioned example where the gas mass flow
qpump through the gas pump 26 is estimated by an affine performance function, dependent
on at least the supplied voltage
U and the reference current
lref, the following expression may be used:
[0058] Any one embodiment previously described may preferably be used in a method for testing
leakage in a vehicle tank assembly 10. For example, a leakage area A
leak may be estimated by utilizing the leakage estimation method and then comparing the
estimated leakage area A
leak to a predetermined threshold value.
[0059] Preferably, the leakage testing method further comprises the step of transmitting
a warning signal if the estimated leakage area A
leak exceeds the predetermined threshold value and/or the step of transmitting an acceptance
signal if the estimated leakage area A
leak is lower than the predetermined threshold value.
[0060] The leakage estimation method and/or the leakage testing method may preferably be
implemented in a computer program product. Thus, such a computer program product,
may comprise a computer program containing computer program code executable in a computer
or a processor to implement at least one of the steps of a aforementioned methods.
The computer program product may preferably be stored on a computer-readable medium
or a carrier wave. The computer program product may preferably be stored in an electronic
control unit (ECU) 32 and the ECU 32 may preferably be located within a vehicle, which
vehicle comprises the vehicle tank assembly 10.
[0061] As may be appreciated when studying the performance functions of the gas pump 26,
it may be preferred to have a method to create performance functions which method
takes into account individual differences between gas pumps 26 and/or a time dependent
change in the performance of a gas pump 26, for example a decrease in performance
due to aging.
[0062] Thus, what is proposed is a method of estimating performances from a plurality of
pump assemblies 34 and/or at least one pump assembly 34 at different time periods.
The performance is indicative of at least the gas mass flow
qpump through the gas pump 26 and each pump assembly 34 comprises the features previously
disclosed with reference to Fig. 2.
[0063] The method comprises the steps of, for each of a plurality of pump assemblies 34
and/or at least one pump assembly 34 at different time periods:
- measuring the performance for a plurality of applied pump electrical currents l;
- estimating the performance by the applied pump electrical current l and thereby determining performance coefficients for a performance function;
- operating the valve 38 in order to guide the gas mass flow qpump through the reference opening 36 and determining the corresponding pump reference
electrical current lref,
- for each performance coefficient, generating a performance coefficient function, which
is dependent on at least the pump reference electrical current Iref.
[0064] For example, if the gas mass flow
qpump may be estimated as a polynomial of the applied pump electrical current / as:
wherein the value of each performance coefficient may be a function of the pump reference
electrical current
lref, i.e.
[0065] Fig. 3 illustrates the electrical current / applied to the gas pump 26 as a function
of time, the pump electrical current / being denoted by lines 44. As may be gleaned
from Fig. 3, when the gas mass flow
qpump is guided through the reference opening 36, a throttling of the gas mass flow
qpump is obtained, resulting in an increase in applied pump electrical current / required
to drive the gas pump 26, as indicated by area B in Fig. 3.
[0066] The valve 38 of the pump assembly 34 may preferably be further operated so that the
gas mass flow
qpump is guided out of the pump assembly 34. If the initial pressure out of the pump assembly
34 is significantly equal to the pressure at the inlet 42, a pressure difference between
the inlet and outlet 42, 40 is substantially zero, resulting in a minimum of applied
electrical current / to the pump, as indicated by area C in Fig. 3. This illustrates
additional steps of a further embodiment of the estimation method which comprises
the steps of operating the valve 38 in order to guide the flow
ppump out of the pump assembly 34 and determining an initial corresponding pump minimum
electrical current
Imin and generating the performance coefficient function, which is dependent on at least
the pump minimum electrical current
lmin. As illustrated by the plurality of lines 44 in Fig. 3, after obtaining the pump
minimum applied electrical current
lmin, the pump electrical current
l may remain at the minimum level or increase with time. An increase in pump electrical
current may indicate that the pump assembly is in fluid communication with a closed
system, for example a tank assembly 10.
[0067] Thus, utilizing the expression in Eq. 27, the following expression may be obtained:
[0068] Furthermore, the pump electrical voltage
U applied may preferably be measured and used when generating the performance coefficient
functions, such as:
[0069] According to a preferred embodiment of the performance estimation method, each performance
function is estimated by an affine performance function, i.e.
[0070] The performance coefficients of the affine performance function are preferably estimated
by utilizing a least-squares method, more preferably a recursive least-squares method.
[0071] The aforementioned pump assembly 34 may preferably form a part of a vehicle tank
assembly 10, wherein the pump assembly 34 is in fluid communication with the rest
of the tank assembly 10. Then, an additional performance of the pump assembly 10 may
be a resulting change in pressure Δ
p in the tank assembly 10 when the pump 26 of the pump assembly 34 is operated.
[0072] The performance coefficient functions may preferably be used when estimating the
output of a pump assembly. However, since this technique has been previously described
with respect to the leakage area estimation methods, it will not be further detailed
here.
[0073] Further modifications of the invention within the scope are feasible. For instance,
the gas mass flow relation used in the aforementioned leakage area estimation method
could take into account the compressibility of the gas.
1. A method of estimating a performance from a plurality of pump assemblies (34) and/or
at least one pump assembly (34) at different time periods, each pump assembly (34)
comprising a gas pump (26), wherein said performance is indicative of at least a gas
mass flow (
qpump) through said gas pump (26), wherein each pump assembly (34) comprises a reference
opening (36) and a gas valve (38) for controlling said gas mass flow (
qpump), said valve (38) being operable to guide said gas mass flow (
qpump) at least either through said reference opening (36) or through an outlet opening
(40), wherein said gas pump (26) is supplied with electrical power,
characterized in that the method comprises the steps of:
- for each of said plurality of pump assemblies (34) and/or said at least one pump
assembly (34) at different time periods:
o measuring said performance for a plurality of applied pump electrical currents (I);
o estimating said performance by said applied pump electrical current (I) and thereby determining performance coefficients for a performance function;
o operating said valve (38) in order to guide said flow (qpump) through said reference opening (36) and determining the corresponding pump reference
electrical current (lref);
- for each performance coefficient, generating a performance coefficient function,
which is dependent on at least said pump reference electrical current (Iref).
2. The method according to claim 1,
wherein the method further comprises the steps of:
- for each of said plurality of pump assemblies (34) and/or said at least one pump
assembly (34) at different time periods:
∘ operating said valve (38) in order to guide said flow (qpump) through said outlet opening (40) and determining an initial corresponding pump minimum
electrical current (Imin);
- for each performance coefficient, generating a performance coefficient function,
which is dependent on at least said pump minimum electrical current (lmin).
3. The method according to claim 1 or 2,
wherein the method further comprises the steps of:
- for each of said plurality of pump assemblies (34) and/or said at least one pump
assembly (34) at different time periods:
o determining a pump electrical voltage (U);
- for each performance coefficient, generating a performance coefficient function,
which is dependent on at least said pump electrical voltage (U).
4. The method according to any ones of claims 1 to 3,
wherein the method further comprises the step of:
- estimating each of said performance functions by an affine performance function.
5. The method according to claim 4,
wherein the method further comprises the step of:
- estimating said coefficients to each of said affine performance functions by utilizing
a least-squares method.
6. The method according to claim 5,
wherein that the method further comprises the step of:
- estimating said coefficients to each of said affine performance functions by utilizing
a recursive least-squares method.
7. The method according to any one of the preceding claims, wherein said pump assembly (34) forms a part of a vehicle tank assembly (10), said pump assembly
(34) being in fluid communication with the rest of said tank assembly (10) and said
pump assembly performance is indicative of at least a change in pressure (Δp) in said tank assembly (10).
8. A method of estimating an output from a pump assembly (34), wherein said output comprises
a gas mass flow (
qpump) through said gas pump (26), wherein said pump assembly (34) is provided with said
performance coefficient functions by utilizing the method according to any one of
claims 1 - 7,
characterized in that the method comprises the steps of:
- operating said valve (38) in order to guide said flow (qpump) through said reference opening (36) and determining a corresponding pump reference
electrical current (lref);
- determining said performance coefficients, based on said pump reference electrical
current (lref);
- operating said valve in order to guide said flow (qpump) through said outlet opening (40);
- determining said applied pump electrical current (l), and
- calculating said output, by utilizing said performance function with said performance
coefficients, wherein said applied pump electrical current (l) is input to said performance function.
9. The method of estimating an output from a pump assembly according to claim 8, when
dependent on any one of claims 2 - 7, wherein the method further comprises the steps
of:
- operating said valve (38) in order to guide said flow (qpump) through said outlet opening (40) and determining a corresponding initial pump minimum
electrical current (lmin), and
- determining said performance coefficients, based on said initial corresponding pump
minimum electrical current (lmin).
10. The method of estimating an output from a pump assembly according to claim 8 or 9,
when dependent on any one of claims 3-7, wherein the method further comprises the
steps of:
- determining an pump electrical voltage (U), and
- determining said performance coefficients, based on said pump electrical voltage
(U).
11. The method of estimating an output from a pump assembly according to any one of claim
8-9, when dependent on claims 7, wherein said output further comprises a change in
pressure (Δp) in said tank assembly (10).
1. Verfahren zum Schätzen einer Leistungsfähigkeit von mehreren Pumpenanordnungen (34)
und/oder mindestens einer Pumpenanordnung (34) in unterschiedlichen Zeiträumen, wobei
jede Pumpenanordnung (34) eine Gaspumpe (26) umfasst, wobei die Leistungsfähigkeit
mindestens einen Gasmassendurchfluss (q
pump) durch die Gaspumpe (26) anzeigt, wobei jede Pumpenanordnung (34) eine Bezugsöffnung
(36) und ein Gasventil (38) umfasst, um den Gasmassendurchfluss (q
pump) zu steuern, wobei das Ventil (38) betreibbar ist, den Gasmassendurchfluss (q
pump) mindestens entweder durch die Bezugsöffnung (36) oder durch eine Auslassöffnung
(40) zu leiten, wobei die Gaspumpe (26) mit elektrischer Leistung versorgt wird,
dadurch gekennzeichnet, dass das Verfahren die folgenden Schritte umfasst:
- für jede der mehreren Pumpenanordnungen (34) und/oder mindestens eine Pumpenanordnung
(34) in unterschiedlichen Zeiträumen:
∘ Messen der Leistungsfähigkeit für mehrere angelegte elektrische Pumpenströme (I);
∘ Schätzen der Leistungsfähigkeit durch die angelegten elektrischen Pumpenströme (I)
und dadurch das Bestimmen der Leistungsfähigkeitskoeffizienten für eine Leistungsfähigkeitsfunktion;
∘ Betreiben des Ventils (38), um den Durchfluss (qpump) durch die Bezugsöffnung (36) zu leiten und den entsprechenden elektrischen Pumpenbezugsstrom
(Iref) zu bestimmen;
- für jeden Leistungsfähigkeitskoeffizienten Erzeugen einer Leistungsfähigkeitskoeffizientenfunktion,
die mindestens von dem elektrischen Pumpenbezugsstrom (Iref) abhängig ist.
2. Verfahren nach Anspruch 1, wobei das Verfahren ferner die folgenden Schritte umfasst:
- für jede der mehreren Pumpenanordnungen (34) und/oder mindestens eine Pumpenanordnung
(34) in unterschiedlichen Zeiträumen:
- Betreiben des Ventils (38), um den Durchfluss (qpump) durch die Auslassöffnung (40) zu leiten und einen entsprechenden elektrischen Anfangspumpenmindeststrom
(Imin) zu bestimmen;
- für jeden Leistungsfähigkeitskoeffizienten Erzeugen einer Leistungsfähigkeitskoeffizientenfunktion,
die mindestens von dem elektrischen Pumpenmindeststrom (Imin) abhängig ist.
3. Verfahren nach Anspruch 1 oder 2, wobei das Verfahren ferner die folgenden Schritte
umfasst:
- für jede der mehreren Pumpenanordnungen (34) und/oder mindestens eine Pumpenanordnung
(34) in unterschiedlichen Zeiträumen:
Bestimmen einer elektrischen Pumpenspannung (U);
- für jeden Leistungsfähigkeitskoeffizienten Erzeugen einer Leistungsfähigkeitskoeffizientenfunktion,
die mindestens von der elektrischen Pumpenspannung (U) abhängig ist.
4. Verfahren nach einem der Ansprüche 1 bis 3, wobei das Verfahren ferner den folgenden
Schritt umfasst:
- Schätzen jeder der Leistungsfähigkeitsfunktionen durch eine affine Leistungsfähigkeitsfunktion.
5. Verfahren nach Anspruch 4, wobei das Verfahren ferner den folgenden Schritt umfasst:
- Schätzen der Koeffizienten für jede der affinen Leistungsfähigkeitsfunktionen durch
Verwenden eines Verfahrens der kleinsten Quadrate.
6. Verfahren nach Anspruch 5, wobei das Verfahren ferner den folgenden Schritt umfasst:
- Schätzen der Koeffizienten für jede der affinen Leistungsfähigkeitsfunktionen durch
Verwenden eines rekursiven Verfahrens der kleinsten Quadrate.
7. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Pumpenanordnung (34)
einen Teil einer Fahrzeug-Tankanordnung (10) bildet, wobei die Pumpenanordnung (34)
in Fluidkommunikation mit dem Rest der Tankanordnung (10) ist und die Leistungsfähigkeit
der Pumpenanordnung mindestens eine Änderung des Drucks (Δp) in der Tankanordnung
(10) anzeigt.
8. Verfahren zum Schätzen einer Ausgabe von einer Pumpenanordnung (34), wobei die Ausgabe
einen Gasmassendurchfluss (q
pump) durch die Gaspumpe (26) umfasst, wobei die Pumpenanordnung (34) mit den Leistungsfähigkeitskoeffizientenfunktionen
durch Verwenden des Verfahrens nach einem der Ansprüche 1-7 versehen ist,
dadurch gekennzeichnet, dass das Verfahren die folgenden Schritte umfasst:
- Betreiben des Ventils (38), um den Durchfluss (qpump) durch die Bezugsöffnung (36) zu leiten und einen entsprechenden elektrischen Pumpenbezugsstrom
(Iref) zu bestimmen;
- Bestimmen der Leistungsfähigkeitskoeffizienten auf der Grundlage des elektrischen
Pumpenbezugsstroms (Iref);
- Betreiben des Ventils, um den Durchfluss (qpump) durch die Auslassöffnung (40) zu leiten;
- das Bestimmen des angelegten elektrischen Pumpenstroms (I) und
- Berechnen der Ausgabe durch das Verwenden der Leistungsfähigkeitsfunktion mit den
Leistungsfähigkeitskoeffizienten, wobei der angelegte elektrische Pumpenstrom (I)
Eingabe an die Leistungsfähigkeitsfunktion ist.
9. Verfahren zum Schätzen einer Ausgabe von einer Pumpenanordnung nach Anspruch 8, wenn
abhängig von einem der Ansprüche 2-7, wobei das Verfahren ferner die folgenden Schritte
umfasst:
- Betreiben des Ventils (38), um den Durchfluss (qpump) durch die Auslassöffnung (40) zu leiten und einen entsprechenden elektrischen Anfangsmindestpumpenstrom
(Imin) zu bestimmen und
- Bestimmen der Leistungsfähigkeitskoeffizienten auf der Grundlage des entsprechenden
elektrischen Anfangsmindestpumpenstroms (Imin).
10. Verfahren zum Schätzen einer Ausgabe von einer Pumpenanordnung nach Anspruch 8 oder
9, wenn abhängig von einem der Ansprüche 3-7, wobei das Verfahren ferner die folgenden
Schritte umfasst:
- Bestimmen einer elektrischen Pumpenspannung (U) und
- Bestimmen der Leistungsfähigkeitskoeffizienten auf der Grundlage der elektrischen
Pumpenspannung (U).
11. Verfahren zum Schätzen einer Ausgabe von einer Pumpenanordnung nach einem der Ansprüche
8 - 9, wenn abhängig von Anspruch 7, wobei die Ausgabe ferner eine Änderung des Drucks
(Δp) in der Tankanordnung (10) umfasst.
1. Procédé d'estimation d'un rendement fourni par une pluralité d'ensembles pompes (34)
et/ou par au moins un ensemble pompe (34) à différentes périodes de temps, chaque
ensemble pompe (34) comprenant une pompe à gaz (26), dans lequel ledit rendement est
indicatif d'au moins un débit massique de gaz (
qpump) à travers ladite pompe à gaz (26), dans lequel chaque ensemble pompe (34) comprend
une ouverture de référence (36) et une soupape à gaz (38) pour contrôler ledit débit
massique de gaz (
qpump), ladite soupape (38) pouvant être actionnée pour guider ledit débit massique de
gaz (
qpump) au moins soit à travers ladite ouverture de référence (36), soit à travers une ouverture
de sortie (40), dans lequel ladite pompe à gaz (26) est alimentée en énergie électrique,
caractérisé en ce que ce procédé comprend les étapes consistant à :
- pour chacun de ladite pluralité d'ensembles pompes (34) et/ou ledit au moins un
ensemble pompe (34) à différentes périodes de temps :
∘ mesurer ledit rendement pour une pluralité de courants électriques de pompe appliqués
(I) ;
∘ estimer ledit rendement par ledit courant électrique de pompe appliqué (I) et déterminer ainsi des coefficients de rendement pour une fonction de rendement
;
∘ actionner ladite soupape (38) afin de guider ledit débit (qpump) à travers ladite ouverture de référence (36) et déterminer le courant électrique
de référence de pompe correspondant (Jref) ;
- pour chaque coefficient de rendement, générer une fonction de coefficient de rendement,
qui est dépendante d'au moins ledit courant électrique de référence de pompe (Iref).
2. Procédé selon la revendication 1, ce procédé comprenant en outre les étapes consistant
à :
- pour chacun de ladite pluralité d'ensembles pompes (34) et/ou ledit au moins un
ensemble pompe (34) à différentes périodes de tempes :
∘ actionner ladite soupape (38) afin de guider ledit débit (qpump)à travers ladite ouverture de référence (40) et déterminer un courant électrique
minimum de pompe correspondant initial (Imin) ;
- pour chaque coefficient de rendement, générer une fonction de coefficient de rendement,
qui est dépendante d'au moins ledit courant électrique minimum de pompe (Imin).
3. Procédé selon la revendication 1 ou 2, ce procédé comprenant en outre les étapes consistant
à :
- pour chacun de ladite pluralité d'ensembles pompes (34) et/ou ledit au moins un
ensemble pompe (34) à différentes périodes de tempes :
∘ déterminer une tension électrique de pompe (U) ;
- pour chaque coefficient de rendement, générer une fonction de coefficient de rendement,
qui est dépendante d'au moins ladite tension électrique de pompe (U).
4. Procédé selon l'une quelconque des revendications 1 à 3, ce procédé comprenant en
outre l'étape consistant à :
- estimer chacune desdites fonctions de rendement par une fonction de rendement affine.
5. Procédé selon la revendication 4, ce procédé comprenant en outre l'étape consistant
à :
- estimer lesdits coefficients à chacune desdites fonctions de rendement affines en
utilisant une méthode des moindres carrés.
6. Procédé selon la revendication 5, ce procédé comprenant en outre l'étape consistant
à :
- estimer lesdits coefficients à chacune desdites fonctions de rendement affines en
utilisant une méthode des moindres carrés récursive.
7. Procédé selon l'une quelconque des revendications précédentes, dans lequel ledit ensemble
pompe (34) fait partie d'un ensemble réservoir de véhicule (10), ledit ensemble pompe
(34) étant en communication fluidique avec le reste dudit ensemble réservoir (10)
et ledit rendement d'ensemble pompe est indicatif d'au moins un changement de pression
(Δp) dans ledit ensemble réservoir (10).
8. Procédé d'estimation d'un débit de refoulement fourni par un ensemble pompe (34),
dans lequel ledit débit de refoulement comprend un débit massique de gaz (
qpump) à travers ladite pompe à gaz (26), dans lequel ledit ensemble pompe (34) est pourvu
desdites fonctions de coefficient de rendement en utilisant le procédé selon l'une
quelconque des revendications 1 à 7,
caractérisé en ce que ce procédé comprend les étapes consistant à :
- actionner ladite soupape (38) afin de guider ledit débit (qpump) à travers ladite ouverture de référence (36) et déterminer un courant électrique
de référence de pompe correspondant (Jref) ;
- déterminer lesdits coefficients de rendement, en se basant sur ledit courant électrique
de référence de pompe (Iref);
- actionner ladite soupape afin de guider ledit débit (qpump) à travers ladite ouverture de sortie (40) ;
- déterminer ledit courant électrique de pompe appliqué (I), et
- calculer ledit débit de refoulement, en utilisant ladite fonction de rendement avec
lesdits coefficients de rendement, ledit courant électrique de pompe appliqué (I) étant entré dans ladite fonction de rendement.
9. Procédé d'estimation d'un débit de refoulement fourni par un ensemble pompe selon
la revendication 8, lorsqu'elle dépend de l'une quelconque des revendications 2 à
7, ce procédé comprenant en outre les étapes consistant à :
- actionner ladite soupape (38) afin de guider ledit débit (qpump) à travers ladite ouverture de sortie (40) et déterminer un courant électrique minimum
de pompe initial correspondant (Imin), et
- déterminer lesdits coefficients de rendement, en se basant sur ledit courant électrique
minimum de pompe correspondant initial (Imin).
10. Procédé d'estimation d'un débit de refoulement fourni par un ensemble pompe selon
la revendication 8 ou 9, lorsqu'elle est dépend de l'une quelconque des revendications
3 à 7, ce procédé comprenant en outre les étapes consistant à :
- déterminer une tension électrique de pompe (U) ; et
- déterminer lesdits coefficients de rendement, en se basant sur ladite tension électrique
de pompe (U).
11. Procédé d'estimation d'un débit de refoulement fourni par un ensemble pompe selon
l'une quelconque des revendications 8 et 9, lorsqu'elle dépend de la revendication
7, dans lequel ledit débit de refoulement comprend en outre un changement de pression
(Δp) dans ledit ensemble réservoir (10).