Methods and system for determining consumption and fuel efficiency in vehicles

• US 20070129878A1
• Filed: 03/31/2006
• Published: 06/07/2007
• Est. Priority Date: 12/07/2005
• Status: Active Grant

• Current Assignee: GeoTab Incorporated
• Original Assignee: Netistix Technologies Corporation (GeoTab Incorporated)
• Inventors: Pepper, Gary
• Granted Patent: US 7,774,130 B2
• Time in Patent Office: Days
• US Class Current: 701/123
• CPC Class Codes: B60W 2530/209 Fuel quantity remaining in tank
• CPC Class Codes: B60W 40/12 related to parameters of the vehicle itself , e.g. tyre models
• CPC Class Codes: B60W 50/0098 Details of control systems ensuring comfort, safety or stability not otherwise provided for
• CPC Class Codes: B60W 50/14 Means for informing the driver, warning the driver or prompting a driver intervention
• CPC Class Codes: F02D 41/1402 Adaptive control

Abstract

A method of determining fuel consumption in a vehicle through the OBDII bus is described. The fuel consumption is determined by using mass air flow (MAF) sensor data or manifold air pressure (MAP) sensor data, and obtaining and applying long term and short term fuel trim values for the vehicle, which respectively characterize deviations of air-to-fuel stoichiometry in the vehicle due to aging and vehicle'"'"'s current operating conditions to determine the corrected fuel consumption in the vehicle. For MAP based method, an independent determining of Volumetric Efficiency of a vehicle'"'"'s engine is also provided. The method is further enhanced by providing various sensing patterns for various sensor data, which depend on the rate of change of the respective data.

Claims

1. A method of determining fuel consumption in a vehicle, comprising the steps of:

(a) determining fuel consumption by using mass air flow (MAF) sensor data or manifold air pressure (MAP) sensor data, including obtaining MAF data or MAP data in the vehicle;

the step (a) comprising;

(b) obtaining long term and short term fuel trim values for the vehicle, which respectively characterize deviations of air-to-fuel stoichiometry in the vehicle due to aging and vehicle'"'"'s current operating conditions, and

(c) correcting fuel consumption in the vehicle determined in the step (a) by applying said long term and short term fuel trim values to determine the corrected fuel consumption in the vehicle.

2. A method as described in claim 1, wherein the steps of obtaining comprise sensing vehicle'"'"'s data through a vehicle'"'"'s bus.

3. A method as described in claim 2, wherein the step (a) comprises determining fuel consumption in the vehicle by using MAP data, only if MAF data is not available for the vehicle.

4. A method as described in claim 1, wherein the step (b) comprises obtaining a number of banks (pairs) of respective fuel trim values for each of the long term and short term fuel trim values, and determining average long term and short term fuel trim values over the respective number of banks.

5. A method as described in claim 3, wherein the number of banks is less or equal to 4.

6. A method as described in claim 2, wherein the step (b) comprises sensing various vehicle'"'"'s data at respective various frequencies, which are substantially inversely proportional to the rate of change of the respective vehicle'"'"'s data.

7. A method as described in claim 2, wherein the steps of sensing comprise sensing vehicle'"'"'s data through onboard diagnostic II (OBDII) bus.

8. A method as described in claim 4, wherein the step (a) comprises determining fuel consumption in the vehicle by using MAF data for the time interval Δ

T=N·

Δ

t_i as follows;

$\frac{1}{{\mathrm{AF}}_{\mathrm{ratio}}\times <br><br>{\mathrm{\rho <br><br>}}_{\mathrm{fuel}}\times <br><br>1000<br><br>\text{\hspace{1em}<br><br>}<br><br>\text{ml/l}}<br><br>\underset{i=1}{\overset{N}{\sum <br><br>}}<br><br>\left(\mathrm{MAF}<br><br>\left(t_i\right)\times <br><br>\stackrel{\_}{{\mathrm{LONGFT}}_i}\times <br><br>\stackrel{\_}{{\mathrm{SHRTFT}}_i}\times <br><br>\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>t_i\right)$

wherein AF_ratio is air-to-fuel stoichiometric ratio, ρ

_fuel is fuel density in g/ml, MAF(t_i), LONGFT_i, and SHRTFT_i are respectively MAF data, average long term, and average short term fuel trim data at time instance t_i.

9. A method as described in claim 3, wherein the step (a) further comprises sensing a revolution per minute (RPM), and intake air temperature (IAT) in the vehicle.

10. A method as described in claim 9, wherein the step (a) comprises determining fuel consumption in the vehicle by using MAP data for the time interval Δ

T=N·

At_i as follows;

$\frac{\mathrm{VE}\times <br><br>\mathrm{ED}\times <br><br>M_{\mathrm{air}}}{120\times <br><br>R\times <br><br>{\mathrm{AF}}_{\mathrm{ratio}}\times <br><br>{\mathrm{\rho <br><br>}}_{\mathrm{fuel}}\times <br><br>1000<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{ml}<br><br>\text{/}<br><br>l}<br><br>\underset{i=1}{\overset{N}{\sum <br><br>}}<br><br>\frac{{\mathrm{RPM}}_i\times <br><br>{\mathrm{MAP}}_i\times <br><br>\stackrel{\_}{{\mathrm{LONGFT}}_i}\times <br><br>\stackrel{\_}{{\mathrm{SHRTFT}}_i}}{\left({\mathrm{IAT}}_i+273.12\right)}<br><br>\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>t_i$

wherein VE is Volumetric Efficiency for the vehicle (unitless), MAP is Manifold Air Pressure (kPa), ED is Engine Displacement (litres), R is ideal gas constant 8.314 kPa K<sup>−

1</sup> mol<sup>−

1</sup>, and M_air is molar mass of air (g/mol)=28.97 g/mol;

RPM_i, MAP(t_i), LONGFT_i, SHRTFT_i and IAT_i are respectively engine'"'"'s Revolution Per Minute (min<sup>−

1</sup>), Manifold Air Pressure sensor data, average long term, average short term fuel trim data, and Intake Air Temperature (degrees Celsius) at time instance t_i.

11. A method as described in claim 3, wherein the step (a) of determining fuel consumption by using MAP data comprises determining vehicle'"'"'s volumetric efficiency (VE) as follows:

(i) selecting time interval and setting VE=1;

(ii) determining total fuel consumed by the vehicle during all selected time intervals according to an independent refuelling measurement (TFC_M);

(iii) determining total fuel consumed by the vehicle during all selected time intervals according to the method of claim 3 (TFC_V) by using the current value of VE;

(iv) updating the current value of VE=TFC_M/TFC_V;

(v) selecting another time interval and repeating the steps (ii) to (iv) a number of times to achieve a required accuracy for the current value of VE.

12. A method as described in claim 11, wherein the step (ii) comprises manual or automatic refuelling measurement at a gas pump.

13. A method as described in claim 7, wherein sensing of various data is performed in one or more of the following ways:

sensing data at respective frequencies, which are substantially inversely proportional to the rates change of respective data;

sensing data consecutively;

sensing data concurrently;

sensing data according to a random selection of their sampling order;

or sensing selected data at a sampling frequency, which is dependent on the value of another data.

14. A method as described in claim 1, wherein the steps (a) and (b) comprise sampling various vehicle'"'"'s data at respective various sampling frequencies, which are based on historic data for the respective vehicle'"'"'s data.

15. A method as described in claim 8, wherein fuel density ρ

_fuel is adjusted according to seasonal temperature variations.

16. A method as described in claim 1, further comprising transmitting the data obtained in any of the steps (a) to (c) from the vehicle to a central host for further processing and storage.

17. A method as described in claim 15, wherein the transmitting to the central host is performed as follows:

wirelessly transmitting the fuel consumption data from the vehicle to a gateway (wireless access point) connected to a communications network, the communications network enabling the transfer of data between the gateway and the central host.

18. A method as described in claim 15, wherein the steps (a) and (c) comprise distributed determining of fuel consumption by using processing power of more than one computer, including initial processing of data in the vehicle, followed by final processing of data at the central host.

19. A method as described in claim 1, further comprising determining fuel efficiency, comprising obtaining an odometer reading for the vehicle, and relating the fuel consumed by the vehicle over the distance identified by the odometer reading for the corresponding time interval to determine fuel efficiency.

20. A method as described in claim 1, further comprising identifying if the vehicle is a hybrid electric vehicle (HEV), and determining fuel consumption in the HEV in accordance with the method of claim 1 during time intervals when the HEV does not operate under electric power.

21. A vehicle interface unit (VIU), comprising:

a (VIU) computer having a CPU and non-volatile memory (NVM);

the VIU computer is connected to a vehicle bus providing access to sensors in the vehicle for collecting vehicle related data through the vehicle bus;

the VIU computer is programmed to determine fuel consumption in the vehicle in accordance with the method of claim 1.

22. A VIU as described in claim 21, wherein the VIU computer comprises a computer program code stored in the NVM for execution by the CPU to perform the steps of the method of claim 1.

23. A VIU as described in claim 21, further comprising a wireless modem connected to the VIU computer and providing communication over a wireless link with a gateway (wireless access point), which is connected to a communications network, the communications network providing transmission of data between the gateway and a central host.

24. A vehicle telemetric system, comprising:

a central host connected to a communications network;

one or more gateways connected to the communications network, the communications network enabling the transfer of data between the gateways and the central host;

a vehicle interface unit (VIU) within a vehicle having access to sensors in the vehicle for collecting vehicle related data through a vehicle'"'"'s bus, the VIU having means for communication over a wireless link with any of said gateways when the vehicle is within a transmission range of one of said gateways;

the VIU comprising a VIU computer having a CPU and non-volatile memory (NVM);

the VIU computer is connected to the vehicle bus and programmed to determine fuel consumption in the vehicle in accordance with the method of claim 1.

25. A vehicle interface unit (VIU) for a vehicle telemetric system, comprising a central host connected to a communications network and one or more gateways connected to the communications network, which enables the transfer of data between the gateways and the central host, the VIU being located in a vehicle and having access to sensors in the vehicle for collecting vehicle related data through a vehicle'"'"'s bus, the VIU having means for communication over a wireless link with any of said gateways, the wireless link being activated when the vehicle is within a transmission range of the one of said gateways, and another wireless link being activated when the vehicle is within a transmission range of another one of said gateways;

the VIU further comprising a VIU computer having a CPU and non-volatile memory (NVM);

the VIU computer is connected to the vehicle'"'"'s bus and programmed to determine fuel consumption in the vehicle in accordance with the method of claim 1.

26. An access system for use in a vehicle telemetric system, the telemetric system comprising a central host connected to a communications network, the access system comprising:

one or more vehicle interface units (VIUs) and a gateway, the gateway being connected to the communications network,

each VIU being located in a different vehicle and having access to sensors in the vehicle for collecting vehicle related data through a vehicle'"'"'s bus, each VIU having means for communication over a wireless link with the gateway, the wireless link being activated when the vehicle is within a transmission range of the gateway;

each VIU comprising a VIU computer having a CPU and non-volatile memory (NVM);

the VIU computer being connected to the vehicle'"'"'s bus and programmed to determine fuel consumption in the vehicle in accordance with the method of claim 1;

the gateway having another memory for storing the fuel consumption data received from the VIU and a gateway means for forwarding the data to the central host.

28. A multi-user motor vehicle telemetric system, comprising:

(a) one or more central hosts connected to a communications network, each central host being associated with one or more users of the system;

(b) one or more gateways connected to the communications network, the communications network enabling the transfer of data between the gateways and the central hosts;

(c) one or more vehicle interface units (VIUs), each placed within a vehicle having access to sensors in the vehicle for collecting vehicle related data through the vehicle'"'"'s bus, each VIU having means for communication over a wireless link to gateways designated to be accessed by said each VIU when the VIU of the vehicle is within a transmission range of one of said designated gateways, and wherein each VIU is associated with one or more of the users;

(d) each central host having means for selecting gateways for collecting data from each VIU which is associated with the users that the central host is associated with;

(e) each gateway having means for recognizing the association between central hosts and VIUs belonging to the same user; and

(f) each VIU comprising a VIU computer having a CPU and non-volatile memory (NVM); and

(g) the VIU computer being connected to the vehicle'"'"'s bus and programmed to determine fuel consumption in the vehicle in accordance with the method of claim 1.

29. A method for collecting vehicle performance data in a multi-user motor vehicle telemetric system, comprising one or more central hosts connected to a communications network, each central host being associated with one or more users of the system, one or more gateways connected to the communications network, the communications network enabling the transfer of data between the gateways and the central hosts, one or more vehicle interface units (VIUs), each placed within a vehicle having access to sensors in the vehicle for collecting vehicle related data, each VIU having means for communication over a wireless link to gateways designated to be accessed by said each VIU when the VIU of the vehicle is within a transmission range of one of said designated gateways, and wherein each VIU is associated with one or more of the users, the method comprising:

(a) at each central host, selecting gateways for collecting data from each VIU which is associated with the users that the central host is associated with;

(b) at each central host specifying for each user the data to be collected from its associated VIUs through data collection profiles which are stored in the central host and the selected gateways;

(c) at each gateway determining the association between central hosts and VIUs belonging to the same user; and

(d) at each VIU, determining fuel consumption in the vehicle where the VIU is placed in accordance with the method of claim 1.

27. A method for determining a vehicle'"'"'s fuel consumption in a vehicle telemetric system comprising a central host connected to a communications network, one or more gateways connected to the communications network, each gateway having a wireless transmission range, a vehicle interface unit (VIU) within a vehicle having access to sensors in the vehicle for collecting vehicle related data through a vehicle'"'"'s bus, the VIU having means for wireless communication with any of said gateways, the method comprising the steps of:

(a) determining fuel consumption by using mass air flow (MAF) sensor data or manifold air pressure (MAP) sensor data, including obtaining MAF data or MAP data in the vehicle;

the step (a) comprising;

(b) obtaining long term and short term fuel trim values for the vehicle, which respectively characterize deviations of air-to-fuel stoichiometry in the vehicle due to aging and vehicle'"'"'s current operating conditions, and

(c) correcting fuel consumption in the vehicle determined in the step (a) by applying said long term and short term fuel trim values to determine the corrected fuel consumption in the vehicle.

and storing the corrected fuel consumption in a VIU memory;

(d) determining if the VIU is within the wireless transmission range of one of the gateways;

(e) forwarding some or all the fuel consumption data from the VIU to the one of said gateways over a wireless link;

(f) forwarding said some or all of the fuel consumption data received by the one of said gateways from the one of said gateways to the central host over the communications network; and

(g) notifying each gateway by the central host regarding said some or all fuel consumption data that have been already received at the central host.