WO2018059970A1

WO2018059970A1 - Method for communicating data between a smart fuel injector and an ecu

Info

Publication number: WO2018059970A1
Application number: PCT/EP2017/073289
Authority: WO
Inventors: David Aaron MOSS
Original assignee: Delphi Technologies Ip Limited
Priority date: 2016-09-27
Filing date: 2017-09-15
Publication date: 2018-04-05
Also published as: GB2554436A; GB2554436B; GB201616409D0

Abstract

(ECU) and a solenoid actuated fuel injector, said fuel injector including a microprocessor associated therewith, wherein said ECU is electrically connected to said injector via a (standard) high-side line and a low connecting lines line in respect of low and high side drive circuits for said solenoid actuator, wherein said data is communicated along one or more of said high or low side lines, comprising the steps of: a) in a first time slot, switching on/activating the low side or high side drive to drive the voltage on the low side and the high side to either a nominally zero voltage or nominally high voltage state respectively; b) in a second timeslot, transmitting one bit of data comprising either a nominal "1" or "0" from said ECU to said injector or vice versa, by either activating or not activating either said high side or low side drive, to bring or keep the low and/or high side lines to either a high or nominally zero level depending on the bit transmitted; and c) repeating steps a) and b) to transmit further bits of data.

Description

METHOD FOR COMMUNICATING DATA BETWEEN A SMART FUEL

INJECTOR AND AN ECU

TECHNICAL FIELD

The invention relates to a method of transmitting data between a fuel injector from and an Engine Control Unit (ECU). It has particular application to systems where the fuel injector includes a microprocessor ("chip"). The invention provides a method where data can be transmitted through standard connections such as low side and high side drive wires i.e. lines..

BACKGROUND OF THE INVENTION

There is a trend with modern fuel injectors to have associated with them, a chip or microprocessor. Such injectors are typically referred to as "smart" injectors. These chips often have memory in which to store various parameters such as injector trim data, The chips also often include microprocessors or circuitry adapted to process data such as data relating to the signals on the driver lines, drive current (e.g. solenoid actuator current) or signals from injector sensors, and/or to transmit such data to the ECU of an engine to provide e.g. feedback control. In addition data is often required to be sent to the injector from e.g. an ECU for e.g. control purposes. Such data may include data relating to activation pulse profile.

Thus with modern injectors, data is advantageously transmitted to and from i.e. between a smart injector and an engine ECU.

Rather than provide additional wiring along which such data can be transmitted, it is known to uses existing wiring for this purposes. Generally the injectors are connected to the ECU via a high side drive line and a low side drive line, which connect high side and low side circuitry used to provide the appropriate power levels to the injector actuator drive (e.g. solenoid or piezo) as well as a ground (earth) line such as a chassis ground connection being provided. Known technology uses these lines to communicate such data. However there are problems in these systems. It is an object of the invention to overcome these problems and to provide a highly efficient robust method of transmission of data between an ECU and smart injectors. SUMMARY OF THE INVENTION

In one aspect is provided a method of communicating data between an Engine Control Unit (ECU) and a solenoid actuated fuel injector, said fuel injector including a microprocessor associated therewith, wherein said ECU is electrically connected to said injector via a (standard) high-side line and a low connecting lines line in respect of low and high side drive circuits for said solenoid actuator, wherein said data is communicated along one or more of said high or low side lines, comprising the steps of: a) in a first time slot, switching on/activating the low side or high side drive to drive the voltage on the low side and the high side to either a nominally zero voltage or nominally high voltage state respectively; b) in a second timeslot, transmitting one bit of data comprising either a nominal "1" or "0" from said ECU to said injector or vice versa, by either activating or not activating either said high side or low side drive, to bring or keep the low and/or high side lines to either a high or nominally zero level depending on the bit transmitted; c) repeating steps a) and b) to transmit further bits of data.

Step a) may comprise switching on /activating said high side drive to drive the voltage on the low side and the high side to a high voltage state, and step b) comprises the transmitting one bit of data comprising either a nominal "1" or "0" from said ECU to said injector or vice versa, by either activating or not activating said low side drive, to keep the low and/or high side lines at a nominally high level or bring them to a nominally zero level depending on the bit transmitted. Step a) may comprises two sub-steps comprising : i) in a first sub-step time slot, switching on/activating the low side or high drive to bring the low side and high sides to either a nominally high level or a nominal voltage of 0V; ii) in a second sub-step time slot, switching on said high side drive or said low side drive to drive said voltage on high and low side lines to nominally high voltage or a voltage level of 0V, said voltage levels in i) and ii) being the two different levels. Step i) may comprise in the first sub-step timeslot, switching on/activating the low side drive to bring the low side and high sides to a nominal voltage of 0V; and step ii) comprises in the second sub-step time slot, switching on said high side drive to drive the voltage on high and low side to nominally high voltages.

In step c) one bit of data comprising either a nominal "1" or "0" may be transmitted from said ECU to said injector or vice versa, by either activating or not activating said low side drive by the transmitting entity, to bring the low side drive to a high or nominally zero level depending on the bit transmitted.

The method may include the step of the receiving entity determining the transmitted bit by detecting the voltage on the low or high side line during time slot in (b).

In step a) the switching may be controlled by the ECU.

The switching may be performed via switches in the respective high and low side drives.

In step c), switching may be controlled by the transmitting entity.

The transmitting entity be he fuel injector, and in step b) the low side line is brought low or kept high zero depending on activation or non- activation of a either high side or low switch on the solenoid side.

The transmitting entity may be the ECU and in step c) the low or high side line is brought low or kept high depending on activation or non- activation of low or high side driver switches.

In step b) the low side line may be brought low or high depending on activation or non-activation of low side driver switches.

Thus is provided a method of communicating data between an ECU and a solenoid actuated fuel injector, said fuel injector including a microprocessor associated therewith, wherein said ECU is electrically connected to said injector via a (standard) high-side line and a low connecting lines line in respect of low and high side drive circuits for said solenoid actuator, wherein said data is communicated along one or more of said high or low side lines, comprising the steps of: a) in a first timeslot, switching on/activating the low side drive to bring the low side and low sides to a nominal voltage of 0V; b) in a second time slot, switching on said high side drive to drive the voltage on high sand low side to an operating (nominally high) voltages; c) in a third timeslot, the transmitting one bit of data comprising either a nominal "1" or "0" from said ECU to said injector or vice versa, by either activating or not activating said low side drive by the transmitting entity, to bring the low side drive to a high or nominally zero level depending on the bit transmitted; d) repeating steps a) b) and c) to transmit further bits of data. The receiving entity may determine the transmitted bit by detecting the voltage on the low side line during time slot (c), In steps a) and b) the switching may be controlled by the ECU. Said d switching may be performed via switches in the respective high and low side drives. In step c), switching may be controlled by the transmitting entity.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example and with reference to the following figures of which:

Figure 1 shows an example of injector drive circuitry which may be part of the ECU;

Figure 2 shows an example of a portion of the injector circuitry for a single injector (e.g. solenoid actuator);

Figure 3 shows a further example of the injector circuitry;

Figure 4 illustrates the methodology according to one aspect.

Figure 5a to d illustrates methodology for specific examples.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The problem(s) of powering and communicating with remote communication circuits (e.g. between smart injectors and an ECU, via standard injector drives (lines) are solved according to one aspect by activating the existing High-side and Low-side drives (lines) in a specific non-overlapping order. This can be referred to as the framework or protocol.

In existing schemes, the line capacitance limits communications bandwidth. In this scheme the line capacitance is used to advantage and enables the remote communication circuits to transmit or receive one bit per complete Low-side, High-side framework cycle. In examples, the high-side and low-side actuations are highly repetitive, enabling power to be filtered off by the remote communication circuit. This is independent of the bit state being transmitted or received.

If power is drawn from both the low and high part of a framework cycle, then DC isolation from chassis is possible. This is an advantage over existing schemes where a DC path to chassis is always required, which may adversely affect the detection threshold levels.

Due to the repetitive nature of the framework, bit stuffing and other such techniques to avoid long sequences of identical bits (i.e. multiple ones or zeros) are unnecessary. This simplifies data encoding and decoding.

Examples of the invention allow data rates of 50,000 bits to 100,000 bits per second to be achieved over normal ECU high-side and low- side drivers.

Figure 1 shows an example of injector drive circuitry which may be part of the ECU and is controlled by the ECU. The figure shows circuitry that provides high side, and low side drives , designated with reference numerals 1 and 2

respectively, to a bank of three injectors (not shown) via respective high side (HS1 HS2 HS3) and low side (LSI LS2 LS3) wires or lines. Typically, for 6- cylinder engines, two such drives are provided. Of course it is to be understood that the invention is equally applicable to engine systems having any number of cylinders/injectors. So for each of three injectors, the circuitry controls the activation of injectors via a high side (and low side line or connections) designated HS1 HS2 HS3 and LSI LS2 LS3 respectively. So the circuit shown provides a high side drive voltage and a low side voltage to three injectors. In the circuit shown the high side drive lines are controlled via switch Ml and for each of the low side lines, are controlled for each of the three injectors by switches M2, M3, and M4 respectively.

The switches are controlled by the ECU. Normally these switches are used to control the activation of the solenoid injectors. When controlling transmission of data from the ECU to the (smart) injector or vice versa, these switches are also controlled according to examples in a specific fashion, that is to say according to a particular protocol or methodology which will be explained hereinafter. The switches are controlled by control pulses /via connections designated HSC for switch Ml and respectively LSC1, LSC2 and LSC3 for switches M4, M3and M2. Figure 2 shows an example of a portion of the injector circuitry for a single injector (e.g. solenoid actuator), and shows the connection of the high side line and low side line to the chip or processor (not shown). On the right hand side of the figure can be seen the injector processor (slave) transmit 4 and injector processor (slave) receive 3 connections/lines where data is respectively transmitted from and to the smart injector (processor) via the low side and the high side input. The coil is shown with reference numeral 20. The activation of low side lines in figure 2 is by switch M5. Figure 3 shows a further example of the injector circuitry showing the

connectivity of the low side wire connections LSI with the chip or processor of the injector. Again switch M5 controls activation of the low side line and selective activation of this switch allows transmission of data ("l"s and "0"s) from the injector/processor to the ECU as will be explained hereinafter.

Figure 4 illustrates the methodology according to one aspect. The top portion (a) of the figure shows the segmentation in the methodology or protocol in time. In other words timeslots. In segment A is the initialisation segment, segment B refers to a synchronisation segment and segment C is the segment where data (a single bit) is transmitted/received. Segment A and B together may be regarded as a form of initialisation segments. Plots (b) and (c) refer to the control pulses dictated from the ECU/injector so the pulse or control signals sent via HSC and LSC1 respectively of figure 1 in relation to injector number 1. Thus these pulses activate appropriate switches such as Ml and M4 (M3/M2). It is to be understood therefore that the timeline plots 4b, 4c, 4d, therefore relate to the control of switches.

Plot (d) shows the control pulse used to control transmission of data. When transmitting data from the ECU to the injector, this control pulse may activate a switch on the high side drive or low side drive. In the example the control pulse preferably activates a switch on the low side drive (it is assumed that the both drives are previously driven high in this case) but it is to be understood that examples so the invention are not limited to this. So for example transmitting data to the first injector the control pulse will selectively control switch M4. (Equally M2 or M3 may be used or any combination thereof). Whether a "0" bit or "1" bit is transmitted is determined whether in the data segment the TX is driven low or whether it remains high (again assuming in the previous segment B the lines are driven high.

According to examples the transmitted (or received) bit is expected in this timeslot (i.e. segment) and if the low side control pulse is high, then in one example it is assumed a "0" is transmitted " If the control pulse is not provided in slot (d) the line remain as they are; so where the lines are previously driven high in segment B, there it is assumes e.g. a "1" is transmitted. Of course in other protocols this may be the other way round - a "1 "transmitted where there is a pulse i.e. high level on the appropriate data transmission line (low side line here) and "0" transmitted if the appropriate switch is not activated and the transmission line (low side in the example) remains low. This will be explained in further detail below.

When transmitting data from the smart injector to the ECU an appropriate switch on the injector side (e.g. switch M5 of figures 2 and 3) is either switched on or not activated off depending whether a "0" or "1" is to be transmitted. Again it is always assumed that in the data segment a "0" or "1" is transmitted dependent on whether control pulse is high or low and the appropriate switch activated (on). So the ECU will assume either a "1" or "0" is transmitted depending on the low (or high side) level.

The plot (e) bottom shows the actual status of e.g. the low side line which is the line used to transmit/receive i.e. recognise data in one example. In the data segment timeslot C, the data is transmitted and in order to transmit a bit "0" or "1", the line (low or high) is either high or low. Where the line sin segment B are driven high previously, whether a "1" or "0" is transmitted depends on whether the low side line (and thus high side line) is driven low or kept high (no action). So the voltage on the transmission line (e.g. low side line) can be of two forms. Reference numeral 6 shows in this example that when a "0" is to be transmitted the low side transmission/receiving line remains high, Conversely where a "1" is to be transmitted the lines (e.g low side) is driven low by activation of the appropriate switches either on the ECU side (to transmit from the ECU) or on the injector side (to transmit from the injector). Methodology: Example 1

It is to be understood that examples will be described where data is transmitted and received with respect to the low side line. However the invention is not limited to this and data may be transmitted alternatively via the high side line. The following example will be described with reference to one injector. The example is equally applicable to transmitting data to or from more of the injectors simultaneously. It is to be noted that all device can receive simultaneously.. but only one device can send data without possible modification. This being due to the wired nature of the connection". If all active transmit devices send a "1" bit the received data bit is a "1". If any transmit device sends a "0" data bit the received data bit is a "0".

Step a)

At the beginning, regardless of the states of the high side and low side lines (whether these are high (e.g. battery or low) zero), the low side in segment A is made active due to control pulse 8 (shown in figure 4c) which switches on switch M4 on the injector side. This consequently brings the low side line down to 0V i.e. to a low level, and due to the inherent connection and low impedance of the solenoid, will also bring the high side line also down to 0V. So in summary this brings both the low and high side lines down to 0 volts. It may be that the low side (or high side line) was previously at 0V or that it was at a high (power e.g.

battery) level.

Thus in summary at the start of the first segment A (timeslot), one or more of the ECU low-side drivers is activated such as M4. This discharges all actuator high- side and low-side lines and line capacitance and brings the system to a known low voltage state; i.e. 0V. Effectively this brings the lines and returns the lines to a logic zero condition. This ensure the bit synch timeslot/segment B will always produce a rising edge for use effectively as a bit clock reference, shown by reference numeral 10 - see step b) below.

Step b) After this, in time slot (segment) B, an activation (control) pulse 9, which is again controlled by the ECU, switches on switch Ml . This activation pulse is thus considered the high side activation pulse. This forces the high side line to go up (e.g. to activation e.g. battery level) and again by virtue of the connection of the solenoid drive the low side line will also be pushed up. Both the high side and low sides are thus driven high (see figure 4e). It is to be noted the low side (outputs ) are driven high by via current flow through the injector coil. This step can be regarded as the synch segment/timeslot B.

In summary therefore, durging the second segment B the ECU low-sides (after being firstly deactivated) a high-side driver is activated. At no time are any of the low-sides conducting at the same time as any associated high-side. This provides a fast rising edge that remote slave actuators should use as a clock reference. Also this charges the high-side and low-side, EMC & line capacitances to battery and delivers power for use by the remote actuator communication circuits.

Steps in segments A and B may be regarded as initialization steps used to prepare the transmitting/and/or receiving side to receive data in time slot /segment B. In other words they act as timing signals

Step c)

In the next timeslot (data segment C) the data is effectively transmitted. The data will comprise a single bit so either a "0" or a "1" will be transmitted.

In the example, it is assumed in order to transmit a "1", from the ECU to the injector, switch M4 is activated via control pulse 9 which will pull the low side line down (i.e. to 0V (this again will also pull the the high side line down to 0V also). Thus figure 4e shows the value of voltage on the low side line as a consequence, shown by reference numeral 7.

Alternatively if a "0" is to be transmitted then the switch M4 will not be activated. There will be no control pulse in the time slot C. In other words no action will be taken. The low side line will remain high (and so to the high side line), and it is assumed by the receiving side that this means a "0" is transmitted. The low side remains high because the charge and capacitance in the injector solenoid will not dissipate especially in such a very short time space. The line and EMC

capacitance that store the charge and will keep the line at a high state.

Thus the injector receiving data processes i.e. looks at the low side line, to obtain the bit sent.

In summary, at the start of the third segment C, all non-signaling high-side and/or low side drivers are disabled. If none of the signaling low-side (or high side drivers) are activated the system high voltage state is retained via the stored energy in the EMC & line capacitance. If any of the signaling low-sides (or high side) are activated (in the master or remote devices) the stored energy in the EMC & line capacitance is discharged, thereby bringing the system to the low voltage state. Dependent on the state of the signaling low- side drivers a single data bit can be encoded. In other words, In the bit data segment, the high side is tuned off ? If no switch is activated (say designating a logical "1" to be transmitted), the voltage at the Low side outputs remains high due to the system capacitances. If a device (ECU or injector) chooses to send a logical "0" action is required. To send a logic Zero the device must pull its low-side to its local Ground. For the ECU this is the ECU 0V and for the injector this is chassis. For a logic "1" no device action is needed. Instead the system and stray capacitance keep the voltage at the required logic high.

Of course alternatively sending a "1" may be performed by activating appropriate switching and "0" transmitted by no action - the logic can thus reversed

The steps in segments A B and C are repeated to transmit further bits. So to clear all the lines regardless of the state the control pulse is sent from the ECU (via LSC1/LSC2/LSC3) or main control of the ECU to set the low side line (and consequently the high side line) to 0V. Alternatively HSC pulse may be used. It is to be noted that in step c) data can be transmitted alternatively from the injector i.e. injector processor (effectively the "slave") to the ECU. Rather than the switch M4 being activated and the appropriate switch on the slave (M5) may be switched on, to bring the low side down to zero level to indicate a "0" is transmitted. If in the mode where data is transmitted from the slave/injector to the ECU a "1" is to be transmitted again the appropriate switch on the injector side is not activated and the low side line will remain at a high level; the ECU will then assume a "1" is transmitted.

Of course it is to be understood in the above examples that the bits "0" and "1" may be designated the other way round; i.e. the assumption protocol is that if the low side line remains high after timeslot B then a "0" is transmitted " if it is low a "1" is transmitted.

Thus by this methodology the low side active control pulse and high side active control pulse act like a clock. The chip or processor on the injector derives a local clock reference thus in essence form the rising edge e.g. the ECU high side driver. The data clock reference 11 is delayed relative to the clock reference 10 shown by arrow D in figure 4 and is positioned within the data segment. Data e.g., is presented on the low side and is sampled at this point.

Using combinations of short duration high-side and low-side drive actuations a framework for messaging and power for communications circuit operation is provided to remote slave actuators from a system master such as a diesel ECU. Thus the framework/protocol consists of a repetitive pulse sequence comprising three segments. Each completed framework cycle is capable of conveying 1 bit of information between the ECU (master) and injectors (slaves) or from a slave/injector to the master/ECU as determined by protocols according to examples.

Figure 5 a to d shows specific examples of the invention and shows timelines equivalent to figure 4. Specifically figure 5a shows that where a data bit "0" is being transmitted by an injector (slave). Figure 5b shows a data bit "1" transmitted by the injector (slave). Figure 5c shows where a data bit "0" is transmitted by the ECU (master). Figure 5d shows where a data bit "1" is transmitted by the ECU (master).

It is to be noted that the steps in segments A and B can be the other way round; i.e. the lines driven high first by switch Ml and then the lines driven low by e.g. LSI . Also when transmitting data the lines may be selectively be driven or kept high/low high by high side drives. However using low side drives is a more effective and cheaper option especially regarding existing circuitry. In a simpler embodiment rather than having three segments time slots, there are just two. According to this general example, in a first timeslot the low/high side lines are driven high or low, depending on the protocol, and in the second time slot data is sent by: i) either keeping the line low or driving high, in the case where in the first step the lines are driven low, or ii) driving the lines the low or keeping the line high, in the case where in the first drives the line high. In other words the initialization and synchronization segments A and B are effectively merged.

Claims

1. A method of communicating data between an Engine Control Unit (ECU) and a solenoid actuated fuel injector, said fuel injector including a microprocessor associated therewith, wherein said ECU is electrically connected to said injector via a (standard) high-side line and a low connecting lines line in respect of low and high side drive circuits for said solenoid actuator, wherein said data is communicated along one or more of said high or low side lines, comprising the steps of:

a) in a first time slot, switching on/activating the low side or high side drive to drive the voltage on the low side and the high side to either a nominally zero voltage or nominally high voltage state respectively;

b) in a second timeslot, transmitting one bit of data comprising either a nominal "1" or "0" from said ECU to said injector or vice versa, by either activating or not activating either said high side or low side drive, to bring or keep the low and/or high side lines to either a high or nominally zero level depending on the bit transmitted.

c) repeating steps a) and b) to transmit further bits of data.

2. A method as claimed in claim 1 wherein step a) comprises switching on /activating said high side drive to drive the voltage on the low side and the high side to a high voltage state, and step b) comprises the transmitting one bit of data comprising either a nominal "1" or "0" from said ECU to said injector or vice versa, by either activating or not activating said low side drive, to keep the low and/or high side lines at a nominally high level or bring them to a nominally zero level depending on the bit transmitted.

3 A method as claimed in claim 1 or 2 wherein said step a) comprises two sub-steps comprising :

i) in a first sub-step time slot, switching on/activating the low side or high drive to bring the low side and high sides to either a nominally high level or a nominal voltage of 0V; ii) in a second sub-step time slot, switching on said high side drive or said low side drive to drive said voltage on high and low side lines to nominally high voltage or a voltage level of 0V, said voltage levels in i) and ii) being the two different levels.

4. A method as claimed in claim 3 wherein step i) comprises in the first sub-step timeslot, switching on/activating the low side drive to bring the low side and high sides to a nominal voltage of 0V; and step ii) comprises in the second sub-step time slot, switching on said high side drive to drive the voltage on high and low side to nominally high voltages.

5. A method claimed in any previous claim, where in step c) one bit of data comprising either a nominal "1" or "0" is transmitted from said ECU to said injector or vice versa, by either activating or not activating said low side drive by the transmitting entity, to bring the low side drive to a high or nominally zero level depending on the bit transmitted.

6. A method as claimed in claims 1 to 6 including the step of the receiving entity determining the transmitted bit by detecting the voltage on the low or high side line during time slot in (b).

7. A method as claimed in claim 1 to 6 wherein in step a) the switching is controlled by the ECU.

8. A method as claimed in claim 1 to 7 wherein said switching in performed via switches in the respective high and low side drives.

9. A method as claimed in claim 1 to 8 wherein in step c), switching is controlled by the transmitting entity.

10. A method as claimed in claim 1 to 9 wherein the transmitting entity is the fuel injector, and in step b) the low side line is brought low or kept high zero depending on activation or non- activation of a either high side or low switch on the solenoid side.

11. A method as claimed in claim 5 wherein said transmitting entity is the ECU and in step c) the low or high side line is brought low or kept high depending on activation or non- activation of low or high side driver switches.

12. A method as claimed in claim 11 wherein in step b) the low side line is brought low or high depending on activation or non-activation of low side driver switches.