Method and system for supplying diesel to a motor vehicle

Abstract

A method controls a system for supplying diesel fuel on a motor vehicle. The system includes a fuel tank, a first pump that is a low-pressure pump taking fuel from the tank and delivering the fuel to a second pump that is a high-pressure pump. The method includes controlling the first pump to regulate the quantity of fuel provided as a function of the needs of the second pump, and determining a geographical position of the vehicle. The first pump is controlled to a maximum pressure level when the vehicle is in one of several predefined probable stopping zones.

Claims

1. A method for controlling a system for supplying diesel fuel to an internal combustion engine on a motor vehicle, the internal combustion engine stopping in response to a stop command, the system comprising a fuel tank, a first pump that is a low-pressure pump taking fuel from the fuel tank and delivering the fuel to a second pump that is a high-pressure pump, the method comprising: controlling, via a control unit of the motor vehicle, a pressure of the first pump to regulate a quantity of fuel provided by the first pump, the pressure being determined by the control unit as a function of needs of the second pump; determining, via the control unit, that a geographical position of the motor vehicle is in a predefined probable stopping zone; and modifying, prior to the stop command being given to the internal combustion engine, the controlling by the control unit to set the pressure in the first pump to a maximum pressure level in response to the control unit determining that the geographical position of the motor vehicle is in the predefined probable stopping zone.

2. The method as claimed in claim 1, wherein the predefined probable stopping zone is one of several predefined probable stopping zones that are acquired by learning.

3. The method as claimed in claim 2, wherein the learning is performed by the motor vehicle acquiring positions when the motor vehicle stops, and a stopping zone is added, via the control unit of the motor vehicle, to a list of the several predefined probable stopping zones upon a predefined number of stops taking place within a perimeter of predefined radius.

4. The method as claimed in claim 3, wherein the control unit of the motor vehicle removes the stopping zone from the list of the several predefined probable stopping zones once no stop has taken place within the stopping zone for a predefined duration.

5. The method as claimed in claim 1, wherein the predefined probable stopping zone is a disc defined by the coordinates of a center and a radius around the center.

6. The method as claimed in claim 1, wherein the maximum pressure level is applied only for a predefined duration.

7. The method as claimed in claim 1, wherein the modifying is performed while the motor vehicle is moving.

8. The method as claimed in claim 1, wherein the modifying includes, after the pressure in the first pump is set to the maximum pressure level, monitoring the motor vehicle for a predefined duration and, when the motor vehicle has not stopped moving upon completion of the predefined duration, returning the controlling by the control unit to set the pressure in the first pump as a function of the needs of the second pump.

9. A system for supplying fuel on a motor vehicle, the system comprising: a fuel tank; a first pump that is a low-pressure pump taking fuel from the fuel tank and delivering it to a second pump that is a high-pressure pump; a control unit that controls the first pump to regulate a quantity of fuel supplied by the first pump as a function of needs of the second pump; and geolocation means for determining a position of the motor vehicle and supplying the position to the control unit, the control unit being configured to implement the method according to claim 1.

10. The system for supplying fuel according to claim 9, wherein the geolocation means includes a global positioning system.

11. A motor vehicle, comprising: the system for supplying fuel according to claim 9.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The invention will be better understood and further features and advantages will appear from reading the description below, the description referring to FIG. 1 which is a diagrammatic view of a fuel supply system according to one embodiment of the invention.

DETAILED DESCRIPTION

(2) A fuel supply system on-board a motor vehicle with an internal combustion engine of the diesel type, in accordance with one embodiment of the invention, conventionally comprises a diesel fuel tank 3, a first pump 1 called the low-pressure pump taking fuel from the tank 3 and delivering it to a second pump 2 called the high-pressure pump, via a first pipe 5 and a diesel filter 50. The second pump 2 supplies the injectors 4 of the internal combustion engine. It is lubricated by the circulation of diesel. The second pump 2 is driven directly by the engine via a mechanical link (not shown). A second pipe 6 is provided to collect the surplus fuel arriving at the second pump 2, at a common rail 7 or at the injectors 4, and return it to the tank 3.

(3) The system also comprises a control unit 8 controlling the first pump 1 to run at a variable speed, in order to regulate the quantity of fuel provided by the first pump 1 as a function of the needs of the second pump 2. To do this, the system comprises a power circuit 9 receiving a signal C from the control unit 8, and an electrical power source S, and providing a control power P to the first pump 1. The electrical power source S supplies direct current. The signal C from the control unit 8 is for example a pulse width modulation signal. This could also be a signal varying between 0 and 10 V or between 4 and 20 mA. The power circuit 9 provides the control power P in the form of width-modulated pulses. The system also comprises a pressure sensor 51 between the diesel filter 50 and the second pump 2, in order to measure the diesel pressure and supply the measurement to the control unit 8. The control unit 8 is configured to regulate the measured diesel pressure to a reference value. The reference value is set at a constant level.

(4) The electrical power source S is connected to a battery 10 via a relay 11. As soon as the vehicle stop command is given, the relay 11 opens and the electrical power S for the first pump 1 is cut. At the same time, no further command to open the injectors 4 is given, which leads to stoppage of the engine.

(5) According to the invention, the system comprises geolocation means 12 for determining the position of the vehicle and supplying this to the control unit 8. The geolocation means 12 use for example the GPS system. The control unit 8 comprises a list of probable stopping zones and compares the current position G provided by the geolocation means 12 with various probable stopping zones on the list. If the control unit 8 determines that the current position G lies in at least one of the zones on the list, it controls the first pump 1 to a maximum pressure level by replacing the regulation command. It maintains the control at the maximum pressure level for a predefined duration, after which it returns to the control level determined by the pressure regulation upstream of the second pump 2.

(6) The probable stopping zones are stored for example with the coordinates of a center and a radius around the center, so as to define the zone as a disc with this center and this radius.

(7) Preferably, the probable stopping zones are acquired by learning. For this, the learning is performed by the acquisition of positions when the vehicle stops. A stopping zone is added to the list of stopping zones if a predefined number of stops has taken place within a same perimeter of predefined radius. Evidently, tests are performed to avoid defining multiple overlapping zones. Similarly, other tests are performed to forget zones in which no stop has taken place for a predefined duration, for example for several weeks or several months.

(8) In operation, the control unit 8 receives information on the position G via the geolocation means 12 and compares this position to each zone on the list of probable stopping zones. If the current position G does not correspond to a zone, the control unit 8 applies the pressure regulation process upstream of the second pump 2 by acting on the control signal C sent to the power circuit 9. If the position corresponds to at least one of the zones, the control unit 8 stores the moment at which this correlation is found for the first time. It applies a control command C for the power circuit 9 to run the pump at maximum speed. The position of the vehicle is always monitored and the pressure regulation is resumed if the vehicle leaves the probable stopping zone. Similarly, the regulation is resumed on expiry of a predefined period from the moment memorized before.

(9) When the engine stops, it and the second pump continue to run for a duration of around 1.5 s. In the same time, the relay 11 opens and the supply to the control circuit 9 and to the first pump 1 is cut. On application of the method according to the invention, the first pump stops around 1.25 s after the loss of power, whereas if the stoppage occurs outside a probable stopping zone, the first pump 1 stops in around 1 s. Lubrication of the second pump is thus maintained for a further 0.25 s, which could reduce its wear.

(10) The invention is not limited to the embodiment which has just been described merely as an example. Variants may be found in the method of memorizing and defining the probable stopping zones, by the calculation of another distance, or by the design of another form of predefined zone, or as a function of actual stopping points.