GB2589364A

GB2589364A - A method of controlling a fluid delivery system

Info

Publication number: GB2589364A
Application number: GB1917370.7A
Authority: GB
Inventors: Genco Callisto; Di Muro David; Wagener Ben
Original assignee: Delphi Automotive Systems Luxembourg SA
Current assignee: BorgWarner Luxembourg Automotive Systems SA
Priority date: 2019-11-28
Filing date: 2019-11-28
Publication date: 2021-06-02
Anticipated expiration: 2039-11-28
Also published as: GB201917370D0; GB2589364B

Abstract

A method of controlling a fluid delivery system 10 for an internal combustion engine (ICE), the system comprises a conduit 13 arranged to fluidly connect the ICE with a fuel source 18, a fuel pump 24 to pump fuel through the conduit, and a water pump 38 to deliver water into the conduit. The method comprises receiving an input signal of a demand for water delivery, determining a target water flow into the conduit to achieve the water demand; determining a boost mode of the water pump, to deliver a boost flow greater than the target flow, and controling the water pump to achieve the demand. Using water delivery with a boosted (greater) flow for a period of time before returning to a normal mode allows the fuel/water mix to more quickly reach the desired water concentration. Also disclosed is a controller, a fluid delivery system and a fluid delivery system controller.

Description

A METHOD OF CONTROLLING A FLUID DELIVERY SYSTEM

TECHNICAL FIELD

The present invention relates to a method of controlling a fluid delivery system for an internal combustion engine. The invention also relates to a fluid delivery system for an internal combustion engine and to a controller for controlling a fluid delivery system.

BACKGROUND

It is known to provide fluid delivery systems for conveying fuel, such as gasoline, to an internal combustion engine (ICE) of a vehicle. Such fluid delivery systems typically comprise a common rail fuel injection system, which is controlled to regulate the delivery of fuel to an array of fuel injectors, which are themselves controlled to inject the fuel into the engine.

Modern fluid delivery systems also include water injection systems that deliver water into the combustion chambers of the engine, which is known to reduce a knock tendency of the engine without enriching the combustion air-fuel ratio. Engine water injection also provides other benefits such as increased fuel economy and engine performance, as well as a decrease in engine emissions.

It is known to provide engine water injection systems which are arranged to inject water into the air intake manifold of the engine. In order to ensure that the water is actually delivered into the combustion chamber, an excess volume of water is injected into the air intake. Overtime, this can lead to the accumulation of residual water droplets which can cause accelerated corrosion and degradation of the engine manifold. Furthermore, it is difficult to accurately control the delivery of water to the combustion chamber using such water delivery systems, which can lead to an unpredictable response from the engine. In particular, the quantity of water delivered to the combustion chambers affects the torque output of the engine. Therefore, it is desirable to precisely control the water delivery into the combustion chamber, in order to achieve the desired engine performance at any given time.

An alternative approach to the air intake water injection systems is to inject water directly into the engine cylinders. However, while these arrangements may offer improved control of the quantity of water that is injected into the engine, they require significant re-engineering of conventional engine components in order to accommodate the water injectors.

It is an aim of the present invention to address the disadvantages associated with the known fluid delivery systems.

SUMMARY OF INVENTION

According to a first aspect of the invention there is provided a method of controlling a fluid delivery system for an internal combustion engine (ICE), the fluid delivery system comprising a conduit arranged to fluidly connect the ICE with a source of fuel, a fuel pump arranged in the conduit to pump fuel through the conduit, and a water pump arranged to deliver water into the conduit, the method comprising: receiving an input signal indicative of a demand for water to be delivered into a combustion chamber of the ICE; determining a target water flow into the conduit which will achieve the water demand; determining a boost operating mode of the water pump based on the target water flow, the boost operating mode being arranged to cause the water pump to deliver a boost water flow which is greater than the target water flow; and transmitting a control signal to control the water pump according to the boost operating mode in order to achieve the water demand.

Advantageously, the method according to the present invention reduces the time it takes to reach the target water flow level into the combustion chamber. Controlling the water flow level in this way reduces engine knocking whilst reducing any of the negative effects caused by excess water being present during combustion. Reducing the knocking in the engine eliminates the need for other anti-knocking strategies, such as late combustion engine control and/or fuel enrichment schemes. It also allows the engine to be configured to output more power, preferably >90kW per litre of engine capacity.

The method may comprise determining a normal operating mode of the water pump based on the water demand, the normal operating mode being arranged to cause the water pump to deliver the target water flow into the conduit; wherein controlling the water pump comprises initially operating the water pump according to the boost operating mode before reverting to the normal operating mode. The control signal may be configured to initially control the water pump according to the boost operating mode before reverting to the normal operating mode. In this way, transmitting the control signal to control the water pump may comprise transmitting a control signal which initially operates the water pump according to the boost operating mode before reverting to the normal operating mode. Alternatively, a first control signal may be transmitted to control the water pump according to the boost operating mode before a second control signal may be transmitted to the water pump to revert control of the water pump to the normal operating mode.

Controlling the water pump may comprise reverting to the normal operating mode after a predetermined time.

The predetermined time may define a boost period of the boost operating mode, the boost period being determined in dependence on the input.

Determining the normal or boost operating modes may comprise determining at least one of an operating speed of the water pump, a flow rate of water in the conduit or a mass of water in the conduit. Controlling the water pump according to the normal or boost operating modes may cause the water pump to operate at a speed, which will at least achieve the desired water demand of the engine.

Controlling the water pump according to the boost or normal operating modes may cause the water pump to operate such that a flow rate, or mass, of water is delivered to the conduit, which will at least achieve the desired water demand of the engine. For example, controlling the water pump according to the boost operating mode may cause the water pump to operate at a speed (or to deliver a flow rate, or mass, of water to the conduit), which is capable of exceeding the desired water demand.

The boost operating mode may comprise a first boost operating mode having a first boost period and a first boost water flow; and a second boost operating mode having a second boost period and a second boost water flow; wherein the control signal causes the water pump to operate according to the first boost operating mode and then the second boost operating mode.

The method may comprise receiving an input signal indicative of a flow of water into the ICE, the control signal being arranged to cause the water pump to revert to the normal operating mode in dependence on receiving an indication that the flow of water into the ICE has achieved a threshold water flow.

The threshold water flow may be less than the target water flow of the normal operating mode.

The input signal comprises information relating to at least one of an engine operating parameter and an engine torque demand.

The controller may be arranged to perform the method according to any one the previous paragraphs.

According to a second aspect of the invention there is provided a fluid delivery system for an internal combustion engine (ICE), the system comprising: a conduit arranged to fluidly connect the ICE with a source of fuel; a fuel pump arranged in the conduit to pump fuel through the conduit to define a pressurised fuel flow; and a water pump arranged to deliver water into the conduit to cause mixing of the water with the pressurised fuel flow.

The water pump may be fluidly connected to the conduit at a location which is upstream of the fuel pump, the fuel pump being configured to introduce water into the fuel before it enters the fuel pump The water pump may be arranged to introduce water into the fuel at the intake of the fuel pump.

The water pump may be arranged to deliver fuel into the conduit at a pressure of at least 10 bar.

According to a further aspect of the invention there is provided a fluid delivery system controller for controlling a fluid delivery system according to any one of previous paragraphs, the controller comprising: an input arranged to receive input signals indicative of a demand for water to be delivered into a combustion chamber of the ICE; a water flow determining module arranged to determine a target flow of water into the conduit, which will achieve the water demand; a boost operating module arranged to determine a boost operating mode of the water pump based on the target water flow, the boost operating mode being arranged to cause the water pump to deliver a boost water flow which is greater than the target water flow; and an output arranged to transmit a control signal to control the operation of the water pump according to the boost operating mode in order to achieve the water demand.

It will be appreciated that the foregoing represents only some of the possibilities with respect to the particular subsystems of a fluid delivery system which may be included, as well as the arrangement of those subsystems with the controller.

Accordingly, it will be further appreciated that embodiments of a fluid delivery system which include other or additional subsystems and subsystem arrangements remain within the scope of the present invention. Additional subsystems may include, for example, systems relating to the operation of a vehicle exhaust system.

The set of instructions (or method steps) described above may be embedded in a computer-readable storage medium (e.g. a non-transitory storage medium) that may comprise any mechanism for storing information in a form readable by a machine or electronic processors/computational device, including, without limitation: a magnetic storage medium (e.g., floppy diskette); optical storage medium (e.g., CD-ROM); magneto optical storage medium; read only memory (ROM); random access memory (RAM); erasable programmable memory (e.g., EPROM ad EEPROM); flash memory; or electrical or other types of medium for storing such information/instructions.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 illustrates a fluid delivery system and its connection to an internal combustion engine (ICE) suitable for use with embodiments of the present invention; Figure 2 illustrates a controller for controlling the fluid delivery system according to an embodiment of the invention; Figure 3 is a graph showing the change in water concentration of the fluid flowing through the fluid delivery system of Figure 1, during operation of the fluid delivery system; Figure 4 is a flow chart showing the method steps of a method suitable for controlling the fluid delivery system according to Figure 1; and Figure 5 is a graph showing the change in the water concentration of the fluid during operation of the fluid delivery system according to the method of Figure 4.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and which illustrate specific embodiments of the invention. These embodiments are described in sufficient detail to enable those of ordinary skill in the art to make and use them.

Figure 1 illustrates the basic architecture of a fluid delivery system 10 configured for operation with a gasoline internal combustion engine (ICE) 12, hereinafter referred to as an engine 12. The fluid delivery system 10 is connected to the engine 12 and provides a conduit 13 through which fluid is supplied to the combustion chambers of the engine 12. In this case the fluid delivery system 10 includes a common rail fuel injection system 14 for injecting fuel into the combustion chambers of the engine 12. In particular, fuel is stored in a fuel tank 18, and is drawn by way of a low pressure pump assembly 20-or lift pump 20 -through a low pressure feed line 22 to a high-pressure pump assembly 24 -or fuel pump 24. The low pressure feed line 22 comprises a tube, or pipe, which is fluidly connected to the lift pump 24 at one end and connected at another end to the fuel pump 24 The high pressure fuel pump 24 is then connected via a high pressure feed line 26 to an accumulator 28 -or common rail 28. The second feed line 26 comprises a tube, or pipe, which is fluidly connected to the fuel pump 24 at one end and at another end to the common rail 28. The fuel pump 24 is driven by the engine 12 to supply fuel at an elevated pressure to the common rail 28. In this way, the first and second feed lines 22, 26 define at least part of the conduit 13 through which the fuel and water are supplied to the engine 12. The conduit 13 is further defined by the common rail 28 and the fuel pump 24.

Fuel injectors 30 are connected to the common rail 28 by respective feed lines 32. Each fuel injector 30 is arranged to supply fuel to a respective cylinder of the engine 12 by injecting the fuel into a combustion chamber of the cylinder under the control of an electronic control unit (not shown) of the engine 12.

A return line 32 of the fluid delivery system 10 provides a secondary connection to the source tank 18. The return line 32 includes a valve at one end (not shown), which prevents fluid from passing through the return line 32 below a given threshold pressure value. In this way, the return line 32 operates as a pressure release mechanism which allows excess fluid to be returned to the fuel tank 18, rather than being transmitted to the injectors 30. The return line 32 is provided with a separator assembly (not shown) which is arranged to separate out the water from the fuel that is recirculated into the fluid delivery system 10. As would be readily understood by a person having ordinary skill in the art, the separator is configured to prevent water being directed into the fuel tank 18. In so doing, the fuel in the fuel tank 18 is rendered free of water such that the concentration of water in the engine fuel supply is controlled by the water delivery system 16.

The fluid delivery system 10 also includes a water delivery system 16 which is arranged to deliver water into the fuel flow which is conveyed to the engine 12 by the fluid delivery system 10. Water for the water delivery system 16 is supplied from a reservoir 34 -or water tank 34 -which is drawn through a water feed line 36, by a water pump 38, and then injected into the fluid delivery system 10.

The water feed line 36 -or third feed line 36 -comprises a tube, or pipe, which provides a fluid connection between the water tank 34 and the conduit 13 of the fluid delivery system 10. A first portion 37 of the water feed line 36 is fluidly connected at one end to the water tank 34 and at another end to the input side of the water pump 38 which resides within the conduit 13. The first portion 37 comprises a filter (not shown) to prevent unwanted debris from entering the water pump 34. A second portion 39 of the water feed line 26 is fluidly connected at one end to the output side, or pressure side, of the water pump 38 and at another end to the low pressure feed line 22 of the conduit 13, where water is then conveyed into the flow of fluid entering the fuel pump 24.

The water feed line 36 includes a valve (not shown) arranged on the pressure side of the water pump 38, which prevents fluid from passing through the water feed line 36 below a given threshold pressure value. The pressure valve prevents water which is present in the water feed line 36 from leaking into the conduit 13 when the water pump 38 is not in operation. The valve also prevents fluid from flowing back up into the water feed line 36.

The water tank 34 is arranged in fluid connection with the water pump 38 to allow water to be pumped to the engine 12 via the conduit 13. The water which is stored in the water tank 34 can be periodically refilled by the vehicle operator via an access tube (not shown). The water tank 34 may be mounted in the vehicle engine compartment or in any other convenient location where space is available. If desired, a further filter or screen may be located within water tank 34 to prevent foreign matter from entering fluid delivery system 10.

During operation of the water delivery system 16, the water pump 38 is operable to pump water to the engine 10 via the conduit 13. The water pump 38 may be of the rotary type and is driven by an electric motor (not shown). The electric motor is electrically connected to a controller 40 of the fluid delivery system 12 in order to control the operation of the water pump 38.

As shown in Figure 1, the water pump 38 is electronically connected to the controller 40 of the fluid delivery system 12. The controller 40 is operable as a command and control interface between various components of the fluid delivery system 12. In order to achieve this, the controller 40 is electrically connected to the fuel pump 24, through which it is able to monitor the flow of fluid (measured in litres per second) which passes through the conduit 13. Alternatively, the controller 40 may be connected to one or more fluid flow sensors which can be arranged at various locations along the conduit 13, and which may be configured to monitor the flow of fluid passing therethrough.

The controller 40 is electrically connected to a water sensor 42 which is mounted to the common rail 28 of the conduit 13, and which is configured to measure the water in the fluid passing through to the engine 10. In this way, the controller 40 is arranged to monitor the concentration of water (i.e. in percentage mass or volume) in the fuel which is being conveyed to the engine 10 by the fluid delivery system 12. According to a preferred embodiment of the invention, the water sensor information may comprise a continuously varying function of water concentration vs. time. In such situations, the water concentration is provided as a percentage, or ratio, of the total fluid volume (measured in millilitres) or total fluid mass (measured in grams) which passes through the conduit 13; and time is measured in seconds.

The controller 40 forms part of a central control system of the fluid delivery system 12. As such, it will be appreciated by the skilled person that the controller 40 may be incorporated into any number of computer based control systems of the vehicle, such as an engine control unit (ECU) of the vehicle, for example. Accordingly, the controller 40 is further arranged to receive inputs relating to at least one of an engine operating parameter, such as engine speed, temperature or power output, and an engine torque demand. In this way, the controller 40 is configured to receive information relating to the speed of the engine, and/or the torque demands of the engine. The engine torque demand may be derived from a vehicle user such, as an engine throttle position, or from an autonomous vehicle control system, as would be understood by a person having ordinary skill in the art.

The controller 40 is arranged to control the operation of the water pump 38 of the fluid delivery system 10 to deliver water to the conduit 13 during operation of the engine 10. To achieve this, the controller 40 comprises a computer system for carrying out suitably prescribed processes and strategies.

Known water delivery systems are arranged to inject water into the air intake manifold of an engine, which typically requires an excess of water to ensure that the desired amount of water actually reaches the combustion chamber. Overtime, this can lead to the accumulation of residual water droplets, which can cause accelerated corrosion and degradation of the engine manifold. Furthermore, such water delivery systems are unable to control the amount of water that is delivered to the combustion chamber, which causes an unpredictable response from the engine.

An alternative approach to the air intake water injection systems is to inject water directly into the engine cylinders which requires significant re-engineering of the engine's components in order to accommodate the water injection apparatus.

The fluid delivery system 10 according to the present invention is arranged such that the water is injected into the fuel which is delivered to the engine 12. As the water and fuel are pumped through the conduit 13, they are thoroughly mixed together to form an emulsion which is then injected into the combustion chamber by the fuel injectors 30. This ensures that the effects of the water on each combustion event can be controlled to ensure a consistent and predictable engine response. Furthermore, by delivering the water to the combustion chambers via the conduit 13, the water delivery system 16 ensures that there can be no risk of water accumulation within the engine 12 because the water is thoroughly mixed with the fuel before it reaches the combustion chamber. The water delivery system 16 also removes the need to modify the engine 12 in order to accommodate a separate water injector within the cylinder head of the engine block.

The water delivery system 16 is shown in Figure 1 as being fluidly connected to the low pressure feed line 22 of the fluid delivery system 10, i.e. upstream of the fuel pump 24. In embodiments, the water feed line 22 is fluidly coupled to the conduit 13 at a location which is as close as possible to the inlet of the fuel pump 24. This advantageous positioning of the water feed line 22 helps to optimise the mixing of fuel and water as they pass through the fuel pump 24. Alternatively, the water delivery system 16 may be arranged such that it is directly coupled to the fuel pump 24 such that water is delivered directly to the input side of the fuel pump 24.

A particular advantage of the arrangement of the fuel delivery system 10, as illustrated in Figure 1, is that the water is delivered to the lower pressure side of the fuel pump 24. Thus, the water pump 38 need only be configured to overcome the pressure of the fuel within the low pressure portion of the conduit 13, which is typically around 5 bar. For such an arrangement, the water pump 38 is configured to supply water to the second portion 39 of the water feed line 36 at around 10 bar. In this way, the water delivery system 16 is configured such that the water flows into the conduit 13 so that the fuel does not flow into the water delivery system 16 whilst it is in operation. A further advantage of this arrangement is that the water flow is combined with the fuel flow at a location along the conduit 13 which is upstream from the fuel pump 24, which ensures that the water and fuel can be mixed together as the fluid is drawn through the fuel pump 24.

In alternative arrangements of the invention, the water delivery system 16 is fluidly coupled to the conduit 13 at a position which is upstream of the fuel pump 24, for example, to the second feed line 26 or to the common rail 28. According to such arrangements, the water pump 38 is configured to pressurise the water such that it can be injected into the pressurised fuel within the conduit 13 to cause mixing of the water with the pressurised fuel flow which passes therethrough.

A specific configuration of the controller 40, according to the present invention, will now be described with reference to Figs. 1, 2 and 3. During operation of the fluid delivery system 10, the water delivery system 16, and in particular the water pump 38, is operated by the controller 40 to deliver water into the fluid which passes through the conduit 13. In particular, the controller 40 is arranged to control the operation of the water pump 38 according to a water pump control strategy 60, as will be explained in more detail below.

The controller 40 comprises a number of processing modules including a water flow determining module 44, a normal mode determining module 46 and a boost mode determining module 48, as shown in Fig. 2. The controller 40 further comprises an input 42 for receiving signals indicative of a demand for water to be delivered to the engine 12, and an output 50 for transmitting control signals to control the operation of the water pump 38.

During operation of the fluid delivery system 12, the controller 40 is arranged to pump water into the conduit 13 in dependence on receiving a demand for water to be delivered to the engine 12. The water demand represents a flow of water in the fluid being delivered by the conduit 13 to the engine 12, which is represented schematically by the dashed horizontal line WT in graph B of Fig. 3. In this instance, the water flow is represented as a water concentration in the fluid which is being delivered to the combustion chamber of the engine 12 (i.e. the water concentration at or near a fluid inlet to the combustion chamber). The water concentration is shown in graph B as a mass percentage; however, it will be appreciated that the water flow may also comprise a volume percentage, a water/fuel ratio; or a water flow rate (mass per unit time).

To achieve the desired water demand, the controller 40 is configured to determine one or more operating modes of the water pump 38 which, when implemented by the water pump 38, are configured to provide a flow of water to the fluid passing through the conduit 13 to the engine 12. In particular, the boost mode determining module 48 is arranged to determine a control strategy for operating the water pump 38 in a boost operating mode. Similarly, the normal mode determining module is arranged to determine a strategy for operating the water pump 38 in a normal operating mode.

The normal operating mode is determined so as to achieve (and maintain) a target water flow -or target water concentration -in the conduit fluid being delivered to the engine 12. The boost operating mode is also determined to achieve the target water flow, but it is configured to do so in a shorter period of time compared to the normal operating mode. The boost operating mode may be configured to substantially exceed the target water flow level, whereas the normal operating mode is arranged to achieve but not substantially exceed the target water flow level in the conduit 13. Advantageously, the controller 40 is arranged, initially, to control the water pump 38 according to the boost operating mode (i.e. in order to quickly reach the desired water concentration) before reverting to the normal operating mode in order to maintain the water flow into the engine 12 at the desired level.

The controller 40 according to the present invention advantageously reduces the time it takes to reach the target water flow level into the combustion chamber of the engine 12. Controlling the water flow level in this way reduces engine knocking whilst reducing any negative effects on the combustion. Reducing the knocking in the engine eliminates the need for other anti-knocking strategies, such as late combustion engine control and fuel enrichment. It also allows the engine to be configured to output more power, such as >90kW per litre of engine capacity.

Each of the boost and normal operating modes comprise information relating to an operating speed of the water pump 38. Alternatively, the boost and normal operating modes comprise information relating to a flow rate, or mass, of water being delivered to the conduit 13. Operation of the fluid delivery system 10 according to the boost and normal operating modes is represented graphically in Fig. 3, in which graph A illustrates the output of the water pump 38 as a function of the number cycles of the engine 12, and graph B illustrates the corresponding change in the flow of water in the fluid flowing into the engine 12.

During operation of controller 40, the input 42 is arranged to receive an input signal which is indicative of a demand for water to be delivered to a combustion chamber of the engine 12. According to an exemplary arrangement, the input signal includes information relating to an operating parameter of the engine, such as an engine speed, as would be understood by the skilled person. Alternatively, the input signal may comprise information relating to an engine torque demand, such as an engine throttle position, for example.

During operation of the engine 12, the fluid being delivered to the engine 12 by the conduit 13 has a predetermined water concentration level, which is determined by the ECU. An increase in engine speed increases the volume of fuel being delivered to the engine 12, which increases the demand for water to be injected into the conduit 13 in order to maintain a predetermined water flow level of the fluid that is conveyed to the engine 12. Accordingly, an increase in engine speed results in the controller 40 receiving an input signal which is indicative of a required change in the flow of water being delivered to the conduit 13 of the fluid delivery system 10. Alternatively, the input signal may contain information relating to a change in the water concentration of the conduit fluid regardless of any change in the engine speed, caused by a desire to reduce engine emissions, for example. The input signal may also be indicative of an engine start-up event, which corresponds to a need for fluid to be pumped to the engine 12.

Upon receiving a demand for water to be delivered to the engine 12, the controller 40 is arranged to determine an output of water from the water pump 38 which will achieve the target water flow which corresponds to the water flow demand. To achieve this, the water flow determining module 44 is configured to determine a target water flow level -or target pump output level PT -which is represented schematically by the dashed horizontal line in graph A of Fig. 3. The pump output level PT corresponds to an output of water from the water pump 38 which will satisfy the demand for water to be delivered to the engine 12. Accordingly, the pump output level PT is determined to be sufficient to achieve the required water concertation in the conduit fluid being delivered to the engine 12.

The boost mode determining module 48 is arranged to determine a 'boost flow' of water to the conduit 13. The boost operating mode is calculated such that it will cause the water pump 38 to exceed the target pump output level PT, as indicated by the bold dashed line in graph A of Fig. 3. The boost operating mode includes a boost output value Pg which corresponds to the boost water flow, which the water pump 38 is controlled to output during the boost operating mode. The boost operating mode further includes a boost time value Tg, which defines the duration of the boost operating mode. In this way, the boost time value TB represents the length of time that the water pump 38 is controlled to operate at the boost output value Pg.

According to the exemplary boost operating mode shown in Fig, 3, the water pump 38 is controlled to start pumping water into the conduit 13 at To, after which the pump output quickly ramps up to the desired boost output value Pg. The output of the pump is then maintained at boost output value PB for the boost time value TB, at which point the output from the water pump 38 is decreased. The effect on the water flow in the conduit fluid due to the water pump 38 being operated in the boost operating mode is represented schematically by the bold dashed line in graph B of Fig. 3, which shows how the water flow begins to rise, at C1, until it reaches and exceeds the target water flow WT, at 02, before gradually decreasing again over time.

The boost operating mode, according to the presently described embodiment, comprises a single control scheme (i.e. the water pump 38 is controlled to operate at a single boost output value PB for a boost time value TB). However, it will be appreciated that in alternative embodiments, the boost operating mode comprises a plurality of distinct control schemes, which can be implemented consecutively, and with each having different output and timing values. Such boost operating modes comprising multiple control schemes may be determined so as to optimise the operation of the water pump 38 in order, for example, to manage water flow demands for different operating conditions of the engine 12. According to such embodiments, the controller 40 may be configured to operate according to a first boost operating mode and then a second boost operating mode. The first boost operating mode comprises a first boost time period (TB1) and a first boost output value (PO. The second boost operating mode comprises a second boost time period (TB2) and a second boost output value (PB2). As explained before, the first and second boost output values (PB1, P82) correspond to a first and second boost water flow being injected into the conduit 13, respectively. Each of the first and second boost output values (PB1, P82) is greater than the target and/or normal output values (PT, PN). The second boost output value (PB2) is substantially lower than the first boost output value (PO. During operation of the fluid delivery system 10, the water pump 38 is controlled to operate according to the first boost operating mode and then the second boost operating mode so as to gradually reduce the water flow down to the normal flow level.

The normal mode determining module 46 is configured to determine a 'normal mode' for operating the water pump 38 such that it will deliver a 'normal flow' of water to the conduit 13 (i.e. a flow of water which will achieve the target water flow in the conduit fluid). A normal operating mode, as indicated by the solid bold line in graph A of Fig. 3, is determined by the normal operating mode determining module 46 to achieve the target pump output level PT. The normal operating mode comprises a normal pump output value PN which corresponds to the output flow from the water pump 38 during normal mode operation of the pump. The normal operating mode also includes a normal time value (not shown), which defines the period of time that the water pump 38 is controlled to operate at the normal output value PN.

According to the exemplary normal operating mode, as shown in Fig. 3, the water pump 38 is controlled to start pumping water into the conduit 13 at To, after which the pump output quickly ramps up to the desired normal output value PN. The output of the pump is then maintained at the normal output value for the normal time value (not shown), or until the demand for the determined water flow into the conduit fluid is terminated.

The change in the water flow in the conduit fluid, due to the water pump 38 being operated in the normal operating mode, is represented schematically by the solid bold line in graph B of Fig. 3, which illustrates how the water flow begins to rise, at Ci, until it reaches the target water flow WT, at Ca. The water flow is then maintained at the target level by the normal operating mode throughout the continued operation of the engine 12.

With particular reference to Fig. 3, there is a time period following the commencement of each of the boost and normal mode operating strategies during which there is no change in the water concentration of the conduit fluid (i.e. between engine cycle numbers Co and Ci). It will be appreciated by the skilled person that this initial delay is due to the time it takes for the flow of water to travel from the water pump 38, through the conduit 13 of the fluid delivery system 10, to the engine 12. Accordingly, the water flow delay may be affected by the location of the water delivery system 16 along the conduit 13.

Each of the normal and boost operating modes are determined by the controller 40 to control an operating parameter of the water pump 38, which may include, for example, the speed of the water pump 38. In particular, the output 50 of the controller 40 is arranged to transmit one or more control signals to operate the water pump 38 according to the normal and boost operating modes. In particular, the output 50 is arranged to transmit a boost control signal to control the water pump 38 according to the boost mode. The output 50 is also arranged to output a normal control signal to control the water pump 38 according to the normal mode. In particular, the normal and boost control signals comprise instructions to control the electric motor to operate the water pump 38 at a determined speed and for a determined time period.

During operation of the fluid delivery system 10, the water delivery system 16, and in particular the water pump 38, is controlled by the controller 40 according to a water pump control strategy 60 -or water pump control method 60, as shown in Fig. 4. The control strategy 60 is primarily directed towards controlling the water concentration of the fluid passing through the conduit 13 of the fluid delivery system 10.

With reference to Figs. 4 and 5, an exemplary operation of the fluid delivery system 10 will now be described for the situation in which the water pump 38 is controlled according to the water pump control strategy 60. The control strategy 60 is represented by the solid line in graph A of Fig. 5, and comprises a computer implemented control method according to an embodiment of the invention.

The water pump control strategy 60 employs at least the boost operating mode to control the water pump 38 in order to deliver a required water flow to the engine 12. The control strategy 60 commences with a first step 52 in which the controller 40 receives, via the input 42, an input signal indicative of a demand for a flow of water to be delivered to a combustion chamber of the engine 12. The water demand represents a target water flow WT in the conduit fluid, which is represented schematically by the dashed horizontal line in graph B of Fig. 5.

In a second step 64 of the method, the water flow determining module 44 determines a target pump output level PT, corresponding to an output of the water pump 38 which will satisfy the required water/fuel ratio corresponding to the received water flow demand. The target pump output level PT is represented schematically by the dashed horizontal line in graph A of Fig. 5.

In a third step 66 of the control strategy 60, the controller 40 determines one or more operation modes of the water pump 38 which, when implemented by the water pump 38, are configured to provide the target water flow WT to the engine 12.

According to a first stage 66a of the third step 66 of the method, the boost mode determining module 48 determines a mode of operating for the water pump 38 which is configured to deliver a 'boost flow' of water (i.e. a boost water flow) to the conduit 13. In a second stage 66b of the third method step 66, the normal mode determining module 46 is configured to determine a normal mode for operating the water pump 38 such that it will deliver a 'normal flow' of water (i.e. a normal water flow) to the conduit 13.

In a fourth step 70 of the method, the output 50 of the controller 40 is arranged to transmit a boost control signal to control the water pump 38 according to the determined boost mode. With reference to graph A of Fig. 5, which illustrates the operation of the fluid delivery system 10 according to the exemplary control strategy 60, the water pump 38 is started at To, after which the pump output quickly ramps up to the boost output value PB, which exceeds the target pump output level PT. The output of the pump is then maintained at the boost output value PB until the boost time value TB is reached.

Upon reaching the boost time value TB the output 50 transmits a normal control signal, a fifth step 72 of the control strategy 60, in order to control the water pump 38 according to the normal operating mode. In so doing, the controller 40 reduces the water pump's output down to the normal output value PN, which substantially matches the target pump output level PT.

The effect of the water control strategy 60 on the water concentration of the fluid being delivered to the engine 12 is illustrated schematically by the solid line in graph B of Fig. 5. In this example, the boost mode is initiated at engine start-up, as indicated by the zero engine cycle value Co. Following start-up of the water pump 38, there is initially no change in the conduit fluid water concentration because of the time it takes for the water to reach the engine 12. At engine cycle the water concentration starts to rise, following which the water concentration rises steadily until it exceeds the target water flow WT, at C2. The water concentration then begins to fall back owing to the control of the water pump 38 having been reverted to the normal operating mode, until it reaches the target water flow WT, at 03.

The water pump 38 is controlled according to the normal mode until it receives, at a sixth step 74 of the control strategy 60, a further input signal -or termination signal -which is indicative of an end to the demand for the flow of water to be delivered to the engine 12. The control strategy 60 then reverts to the start and awaits the next input signal.

The termination signal includes information relating to the operating parameters of the engine 12 and/or an engine torque demand. According to an exemplary arrangement, the termination signal corresponds to a situation in which the engine 12 transitions from a high load condition, in which water is needed in the fuel to reduce vehicle emissions, to a low load condition, during which the demand for water is significantly reduced.

Alternatively, the controller 40 may be arranged to monitor the water concentration of the fluid in the conduit 13 by receiving and interpreting water sensor signal inputs, for example, and thereby determining when (and/or whether) the target water flow has been exceeded. Such a determination would result in a temporary halt to the flow of water into the conduit 13 in order to maintain the target water flow level. The controller 40 is further arranged to determine, based on the water sensor signals, as to when (and/or whether) to restart the water delivery system 16 in dependence on the water flow level having dropped below the target flow value. In this way, the controller 40 is arranged to operate the fluid delivery system 10 according to a continuous feedback protocol in order to ensure that the desired flow of water is maintained. It will be appreciated that alternative feedback protocols may be applied to the operation of the fluid delivery system 10 without departing from the scope of the present invention.

According to an exemplary arrangement of the fluid delivery system 10, the termination signal comprises a demand from the user to switch off the engine 12. Accordingly, this engine switch-off command corresponds to an end to the flow of water into the conduit 13, since there is no longer any requirement for fluid to be delivered to the engine 12.

The primary function of the controller 40 is to determine a set of water pump operating parameters according to the normal and boost operating modes, which will each achieve the target water flow, but will each do so over different timescales. Advantageously, the boost operating mode provides a means of achieving the target water flow in a relatively short period of time, whereas the normal operating mode is slower to obtain the target water flow, but is ideally suited to maintaining the water concentration in the conduit fluid over the duration of the engine's operation.

The examples described herein are representative only and the skilled reader will appreciate other specific architectures are possible. Moreover, many of the components of the fuel delivery system are conventional and as such would be familiar to the skilled reader. For example, the diagram of Fig. 1 should be taken as a representation of an exemplary fluid delivery system 12, only. Alternative configurations of fluid delivery systems are known and it is expected that other known components may be incorporated in addition to or as alternatives to the components shown in and described with reference to Fig. 1. Such changes would be within the capabilities of the skilled person.

The fluid delivery system of the present invention is adapted for use with a gasoline engine. Alternatively, the fluid delivery system of the present invention can also be used with diesel engines. Such diesel fuel systems run at higher pressures of typically up to 3000 bar. Irrespective of which of the above described types of fluid delivery system is used (i.e. gasoline or diesel) the water delivery system and control methods of the present invention can be incorporated into the fluid delivery system leading to the advantageous control of the flow of water into the engine. It will be appreciated that adaptations can be made to the fluid delivery system, so that it is better suited for use with a non-gasoline engine, without departing from the scope of the present invention. For example, each of the injectors 30 of the engine 12, as shown in Fig. 1, may be provided with a separate return line to convey excess fluid to the fuel tank 18, in addition to the return line 32.

In specific exemplary arrangements of the fluid delivery system 10, the controller is arranged to monitor the water concentration of the fluid in the conduit 13, by receiving and interpreting water sensor signal inputs, and thereby determining when, and/or whether the boost mode operation of the water pump 38 has reached the target water flow.

The controller 40 is further arranged to control the water pump 38 to revert to the normal mode of operation in dependence on the determination that the target water flow has been reached. In an exemplary arrangement the controller 40 is arranged to control the water pump 38 to revert to the normal operating mode in dependence on receiving an indication that the flow of water into the engine has achieved a threshold water flow level, wherein the threshold water flow level is less than the target water flow of the normal operating mode (i.e. the target pump output level PT, as shown in Fig. 4). In so doing, the controller 40 is able to preemptively switch to the normal operating mode, before the boost operating mode has reached the target flow level, so that the water flow in the conduit fluid doesn't overshoot the target flow level.

In the above described arrangements of the fluid delivery system 10, controlling the flow of water into the conduit 13 is determined by adjusting the operation of the water pump 38. However, it will be appreciated that the flow of water may be determined by other suitably configured means, without departing from the scope of the present invention. For example, the flow of water into the conduit 13 may be controlled by a variable flow valve arrangement arranged in the water feed line 22 of the fluid delivery system 10. The variable flow valve may be controlled by the controller 40 to adjust the flow of water being injected into the conduit 13 by opening and closing the valve in accordance with the control method 60, as described above. In such a situation, the water pump 38 may be configured to operate a single operating speed in order to maintain a substantially constant water pressure in the portion of the water feed line 22 which precedes the controllable valve.

Furthermore, the water flow determining module 44, the normal mode determining module 46 and the boost mode determining module 46 are each provided as algorithmic instances on a processor of the controller 40. The processor is arranged to carry out the functions of each module in response to a suitable demand or instruction. Alternatively, each of the controller's modules 44, 46 and 48 may be provided within any number of separate physical processing units, as would be readily understood by the skilled person.

It will also be appreciated that suitable connection apparatus may be provided to interconnect the controller 40 and the various components of the fluid delivery system 12. The interconnections may be direct or 'point to point' connections, or may be part of a local area network (LAN) operated under a suitable protocol (CAN-bus or Ethernet for example). Also, it should be appreciated that rather than using cabling, the control commands may be transmitted wirelessly over a suitable wireless network, for example operating under WiFiTM or ZigBeeTM standards (I EEE802.11 and 802.15.4 respectively).

List of references fluid delivery system 10 internal combustion engine (ICE) 12 fuel injection system 14 water delivery system 16 fuel tank 18 lift pump 20 feed line 22, 26 fuel pump 24 common rail 28 fuel injectors 30 return line 32 water tank 34 water feed line 36 water feed line first portion 37 water pump 38 water feed line second portion 39 controller 40 input 42 water flow determining module 44 normal mode determining module 46 boost mode determining module 48 output 50

Claims

CLAIMS: 1. A method of controlling a fluid delivery system (10) for an internal combustion engine (ICE), the fluid delivery system (10) comprising a conduit (13) arranged to fluidly connect the ICE (12) with a source of fuel (18), a fuel pump (24) arranged in the conduit (13) to pump fuel through the conduit (13), and a water pump (38) arranged to deliver water into the conduit (13), the method comprising: receiving an input signal indicative of a demand for water to be delivered into a combustion chamber of the ICE (12); determining a target water flow into the conduit which will achieve the water demand; determining a boost operating mode of the water pump (38) based on the target water flow, the boost operating mode being arranged to cause the water pump (38) to deliver a boost water flow which is greater than the target water flow; and transmitting a control signal to control the water pump (38) according to the boost operating mode in order to achieve the water demand.
2. A method according to claim 1, comprising determining a normal operating mode of the water pump based on the water demand, the normal operating mode being arranged to cause the water pump (38) to deliver the target water flow into the conduit (13); wherein controlling the water pump (38) comprises initially operating the water pump (38) according to the boost operating mode before reverting to the normal operating mode.
3. A method according to claim 2, wherein the controlling the water pump (38) comprises reverting to the normal operating mode after a predetermined 30 time.
4. A method according to claim 3, wherein the predetermined time defines a boost period (TB) of the boost operating mode, the boost period (TB) being determined in dependence on the input signal.
5. A method according to any one of claims 1 to 4, wherein determining the normal or boost operating modes comprises determining at least one of an operating speed of the water pump (38), a flow rate of water in the conduit (13) or a mass of water in the conduit (13).
6. A method according to any one of claims 1 to 5, wherein the boost operating mode comprises: a first boost operating mode having a first boost period and a first boost water flow; and a second boost operating mode having a second boost period and a second boost water flow; wherein the control signal causes the water pump to operate according to the first boost operating mode and then the second boost operating mode.
7. A method according to any one of claims 1 to 6, wherein the method comprises receiving an input signal indicative of a flow of water into the ICE (12), the control signal being arranged to cause the water pump (38) to revert to the normal operating mode in dependence on receiving an indication that the flow of water into the ICE (12) has achieved a threshold water flow.
8. A method according to claim 7, wherein the threshold water flow is less than the target water flow of the normal operating mode.
9. A method according to any one of claims 1 to 8, wherein the input signal comprises information relating to at least one of an engine operating parameter and an engine torque demand.
10. A controller arranged to control a fluid delivery system (10), wherein the controller (40) is arranged to perform the method according to any one of claims 1 to 9.
11. A fluid delivery system for an internal combustion engine (ICE), the fluid delivery system (10) comprising: a conduit (13) arranged to fluidly connect the ICE with a source of fuel (18); a fuel pump (24) arranged in the conduit (13) to pump fuel through the conduit (13) to define a pressurised fuel flow; and a water pump (38) arranged to deliver water into the conduit (13) to cause mixing of the water with the pressurised fuel flow.
12. A fluid delivery system according to claim 11, wherein the water pump (38) is fluidly connected to the conduit (13) at a location which is upstream of the fuel pump (24), the fuel pump (24) being configured to introduce water into the fuel before it enters the fuel pump (24)
13. A fluid delivery system according to claim 12, wherein the water pump (38) is arranged to introduce water into the fuel at an intake of the fuel pump (24).
14. A fluid delivery system according to any one of claims 11 to 13, wherein the water pump (38) is arranged to deliver fuel into the conduit (13) at a pressure of at least 10 bar.
15. A fluid delivery system controller for controlling a fluid delivery system (10) according to any one of claims 11 to 14, the controller (40) comprising: an input (42) arranged to receive input signals indicative of a demand for water to be delivered into a combustion chamber of the ICE (12); a water flow determining module (44) arranged to determine a target flow of water into the conduit (13), which will achieve the water demand; a boost operating module (48) arranged to determine a boost operating mode of the water pump (38) based on the target water flow, the boost operating mode being arranged to cause the water pump (38) to deliver a boost water flow which is greater than the target water flow; and an output (50) arranged to transmit a control signal to control the operation of the water pump (38) according to the boost operating modes in order to achieve the water demand.