SE542338C2

SE542338C2 - A system and a method for controlling operation of a starter for a combustion engine

Info

Publication number: SE542338C2
Application number: SE1750169A
Authority: SE
Inventors: Mikael Nordin; Susanna Jacobsson
Original assignee: Scania Cv Ab
Priority date: 2017-02-20
Filing date: 2017-02-20
Publication date: 2020-04-14
Also published as: BR102018002753A2; DE102018001114A1; SE1750169A1; DE102018001114B4

Abstract

The invention relates to a method for controlling operation of a starter (220) for a combustion engine (230) during a start-up phase, comprising the steps of:- activating (s410) said starter (220);- continuously determining (s420) an engine speed course of said combustion engine (230);- continuously determining (s430) a mean slope of said determined engine speed course;- on the basis of said determined mean slope, predicting (s440) if a predetermined engine speed will be reached without operation of said starter (220); and,- if decided that said predetermined engine speed will be reached without operation of said starter (220), deactivating (s450) said starter (220).The invention relates also to a computer program product comprising program code (P) for a computer (200; 210; 500) for implementing a method according to the invention. The invention relates also to a system for controlling operation of a starter (220) for a combustion engine during a start-up phase and a motor vehicle (100) equipped with the system.

Description

A system and a method for controlling operation of a starter for a combustion engine TECHNICAL FIELD The present invention relates to a method for controlling operation of a starter for a combustion engine during a start-up phase. The invention relates also to a computer program product comprising program code for a computer for implementing a method according to the invention. It relates also to a system for controlling operation of a starter for a combustion engine during a start-up phase and a motor vehicle equipped with the system.

BACKGROUND ART Vehicles, such as trucks and buses, having a combustion engine are often equipped with a starter, also denoted start motor. This starter may be electrically connected to and powered by a vehicle battery. When the engine is started, either manually by an operator or automatically by e.g. a start-and-stop function, the starter is activated and powered by said battery. The starter is arranged with a gear which during operation is set in position for engaging with a fly-wheel of the engine and when being dis-activated set in a position not engaging with the fly-wheel. Hereby the starter provides torque for cranking up the combustion engine during a start phase.

De-activation of said starter is today performed in at least two different ways. According to a first example de-activation of the starter is performed when the engine has reached a certain predetermined engine speed value, such as e.g. 450 rpm, and a predetermined period of time has lapsed thereafter, e.g. 0,2 or 0,3 seconds. Hereby the engine may reach a predetermined target engine speed exceeding said predetermined engine speed value. This method is not optimal, in particular paying regard to various engine temperatures at start. If the engine is relatively cold it may only reach e.g. 500 rpm when the starter is de-activated. If a predetermined target engine speed is higher, such as e.g. 800 rpm, this is clearly insufficient. If the engine is relatively warm it may reach a predetermined target engine speed when the starter is de-activated.

According to a second example de-activation of the starter is performed when the amplitude of oscillations of the engine speed course are lower than a predetermined value. During a start process of a combustion engine ignition of fuel in various cylinders is causing oscillations of the engine speed. When the engine speed is reaching idle engine speed the amplitude of the oscillations is decreasing and the course of the engine speed is becoming smoother.

US2011088647 relates to a method for starting an internal combustion engine with startstop function.

SUMMARY OF THE INVENTION An object of the present invention is to propose a novel and advantageous method for controlling operation of a starter for a combustion engine during a start-up phase.

Another object of the invention is to propose a novel and advantageous system and a novel and advantageous computer program for controlling operation of a starter for a combustion engine during a start-up phase.

Another object of the invention is to propose a novel and advantageous system and a novel and advantageous computer program providing a cost effective and reliable controlling operation of a starter for a combustion engine during a start-up phase.

Yet another object of the invention is to propose a method, a system and a computer program achieving a robust, accurate and automated controlling operation of a starter for a combustion engine during a start-up phase.

Yet another object of the invention is to propose an alternative method, an alternative system and an alternative computer program for controlling operation of a starter for a combustion engine during a start-up phase.

Some of these objects are achieved with a method according to claim 1. Other objects are achieved with a system in accordance with what is depicted herein. Advantageous embodiments are depicted in the dependent claims. Substantially the same advantages of method steps of the innovative method hold true for corresponding means of the innovative system.

According to an aspect of the invention there is provided a method for controlling operation of a starter for a combustion engine during a start-up phase, comprising the steps of: - activating said starter; - continuously determining an engine speed course of said combustion engine; - continuously determining a mean slope of said determined engine speed course; - on the basis of said determined mean slope, predicting if a predetermined engine speed will be reached without operation of said starter; and, - if decided that said predetermined engine speed will be reached without operation of said starter, deactivating said starter.

The method further comprises the steps of: - determining an output voltage of a starter battery; - if said output voltage is below a predetermined value, de-activating the starter operation after a predetermined time period when a predetermined engine speed is reached. This advantageously provides robustness in case of an inertial start.

By determining the mean slope as a time derivative of the first order of said determined engine speed course from the very beginning, or at an early stage, of a start-up phase of said engine it is possible to predict, at a relatively early point of time, if said engine will reach a predetermined target engine speed, such as idle speed. Said time derivative of the first order of said determined engine speed course may be determined continuously.

By determining a time derivative of the first order of said determined engine speed course from the very beginning, or at an early stage, of a start phase of said engine it is possible to predict/determine/estimate/calculate, at a relatively early moment of time, if said engine will reach said predetermined target engine speed, such as idle speed. Said time derivative of the first order of said determined engine speed course may be determined continuously.

If the determined mean slope presents certain characteristics it may be determined that the starter can be de-activated. This de-activation of the starter may thus advantageously be performed at an earlier stage compared to the depicted prior art solutions. This provides a number of advantages compared to the prior art solutions. One such characteristics may be that the mean slope is exceeding a predetermined value during a certain period of time.

Hereby the starter does not have to be activated and operating too long time, meaning that said starter only is run as long as necessary. Over time, involving a number of crank up phases of the engine, reduced wear of a starter ring of a fly wheel of the engine, compared to prior art solutions, is advantageously achieved. Over time, reduced wear of contact surfaces of a starter solenoid is also achieved compared to prior art solutions. This means that a life operational time of the starter is achieved. Less maintenance and upheld performance regarding said starter may thus be achieved.

The inventive method advantageously provides a possibility to disengage/de-activate said starter at a proper engine speed of the engine, still allowing the engine to reach the predetermined target engine speed without further assistance by the starter. Herby reduced risk that the starter is generating electric current (being lead back to an electric power source of the starter) is advantageously achieved. The present invention is thus providing a safer system for controlling operation of a starter for a combustion engine during a start-up phase.

Said predetermined target engine speed may be any suitable engine speed. Said predetermined target engine speed may be an idle engine speed. Said predetermined target engine speed may be e.g. 500 rpm, 800 rpm or any other chosen idle speed. Said predetermined engine speed may be determined on the basis of the characteristics of said engine.

The mean slope of said determined engine speed course may be determined on the basis of unfiltered engine speed course values. Thus, according to an example, no filter algorithm is necessary to be applied to the engine. This advantageously is reducing the amount of required data processed by means of a control unit. The time derivative of the first order of said determined engine speed course may be determined in a number of different suitable ways. According to one example said time derivative of the first order may be determined on the basis of a number of identified top values of said engine speed course. According to one example said time derivative of the first order may be determined on the basis of a number of identified bottom values of said engine speed course. According to one example said time derivative of the first order may be determined on the basis of a number of identified engine speed values of said engine speed course indicating a change of sign of a time derivative of the second order. In other words, said time derivative of the first order may be determined on the basis of a number of identified engine speed values of said engine speed course indicating a change from concave up to concave down and/or a change from concave down to concave up.

The method may comprise the step of: - deciding that said predetermined engine speed will be reached without operation of said starter when a mean slope of said determined engine speed course exceeding a first predetermined value is detected. This first predetermined value may be e.g. 800 rpm/s or 600 rpm/s. Said first predetermined value may be any chosen idle speed. According to an example it is decided that said predetermined engine speed will be reached without operation of said starter if said mean slope of said determined engine speed course is exceeding said first predetermined value during a predetermined amount of time after activation of said starter.

The method may comprise the steps of: - providing additional fuel for combustion to said engine if a mean slope of said determined engine speed course is below a second predetermined value; and - deactivating said starter when an idle engine speed of said engine is detected. This second predetermined value may be e.g. 500 rpm/s or 400 rpm/s. Said second predetermined value may be any chosen idle speed. Hereby a suitable extra amount of fuel is provided to said engine for securing proper operation of the engine during said start-up phase. This advantageously provides robustness in case of a so called cold start of said engine.

According to an embodiment there is provided a system for controlling operation of a starter for a combustion engine during a start-up phase, comprising: - means arranged for activating said starter; - means arranged for continuously determining an engine speed course of said combustion engine; - means arranged for continuously determining a mean slope of said determined engine speed course; - means arranged for, on the basis of said determined mean slope, predicting if a predetermined engine speed will be reached without operation of said starter; and, - means arranged for, if decided that said predetermined engine speed will be reached without operation of said starter, deactivating said starter.

The system may comprise: - means arranged for deciding that said predetermined engine speed will be reached without operation of said starter when a mean slope of said determined engine speed course exceeding a first predetermined value is detected.

The system may comprise: - means arranged for providing additional fuel for combustion to said engine if a mean slope of said determined engine speed course is below a second predetermined value; and - means arranged for deactivating said starter when an idle engine speed of said engine is detected.

The system may comprise: - means arranged for determining an output voltage of a starter battery; - means arranged for, if said output voltage is below a predetermined value, deactivating the starter operation after a predetermined time period when a predetermined engine speed is reached.

According to an aspect of the invention there is provided a vehicle comprising a system according to what is presented herein. Said vehicle may be any from among a truck, bus or passenger car. According to an embodiment the system is provided for a marine application or industrial application.

According to an aspect of the invention there is provided a computer program for controlling operation of a starter for a combustion engine during a start-up phase, wherein said computer program comprises program code for causing an electronic control unit or a computer connected to the electronic control unit to perform anyone of the method steps depicted herein, when run on said electronic control unit or said computer.

According to an aspect of the invention there is provided a computer program for controlling operation of a starter for a combustion engine during a start-up phase, wherein said computer program comprises program code stored on a computer-readable medium for causing an electronic control unit or a computer connected to the electronic control unit to perform anyone of the method steps depicted herein.

According to an aspect of the invention there is provided a computer program for controlling operation of a starter for a combustion engine during a start-up phase, wherein said computer program comprises program code stored on a computer-readable medium for causing an electronic control unit or a computer connected to the electronic control unit to perform anyone of the method steps depicted herein, when run on said electronic control unit or said computer.

According to an aspect of the invention there is provided a computer program product containing a program code stored on a computer-readable medium for performing anyone of the method steps depicted herein, when said computer program is run on an electronic control unit or a computer connected to the electronic control unit.

According to an aspect of the invention there is provided a computer program product containing a program code stored non-volatile on a computer-readable medium for performing anyone of the method steps depicted herein, when said computer program is run on an electronic control unit or a computer connected to the electronic control unit.

Further objects, advantages and novel features of the present invention will become apparent to one skilled in the art from the following details, and also by putting the invention into practice. Whereas the invention is described below, it should be noted that it is not confined to the specific details described. One skilled in the art having access to the teachings herein will recognise further applications, modifications and incorporations in other fields, which are within the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS For fuller understanding of the present invention and its further objects and advantages, the detailed description set out below should be read in conjunction with the accompanying drawings, in which the same reference notations denote similar items in the various diagrams, and in which: Figure 1 schematically illustrates a vehicle according to an embodiment of the invention; Figure 2 schematically illustrates a system according to an embodiment of the invention; Figure 3a schematically illustrates a diagram according to an aspect of the invention; Figure 3b schematically illustrates a diagram according to an aspect of the invention; Figure 4a is a schematic flowchart of a method according to an embodiment of the invention; Figure 4b is a schematic function diagram of a method according to an embodiment of the invention; and Figure 5 schematically illustrates a computer according to an embodiment of the invention.

DETAILED DESCRIPTION Figure 1 depicts a side view of a vehicle 100. The exemplified vehicle 100 comprises a tractor unit 110 and a trailer 112. The vehicle 100 may be a heavy vehicle, e.g. a truck or a bus. It may alternatively be a car.

It should be noted that the inventive system is applicable to various vehicles, such as e.g. a mining machine, tractor, dumper, wheel-loader, platform comprising an industrial robot, forest machine, earth mover, road construction vehicle, road planner, emergency vehicle or a tracked vehicle.

It should be noted that the invention is suitable for application in various systems comprising a combustion engine and an associated starter. It should be noted that the invention is suitable for application in any combustion engine having a starter and is therefore not confined to engine arrangements for motor vehicles. The innovative method and the innovative system according to one aspect of the invention are well suited to other platforms which comprise a combustion engine and a starter than motor vehicles, e.g. watercraft. The watercraft may be of any kind, e.g. motorboats, steamers, ferries or ships.

The innovative method and the innovative system according to one aspect of the invention are also well suited to systems which comprise industrial combustion engines and/or combustion engine-powered industrial robots and an associated starter.

The innovative method and the innovative system according to one aspect of the invention are also well suited to various kinds of power plants, e.g. an electric power plant which comprises a combustion engine-powered generator and a starter.

The innovative method and the innovative system are also well suited to various combustion engine systems comprising a starter.

The innovative method and the innovative system are well suited to any engine system which comprises an engine, e.g. on a locomotive or some other platform, and an associated starter.

The term "link" refers herein to a communication link which may be a physical connection such as an opto-electronic communication line, or a non-physical connection such as a wireless connection, e.g. a radio link or microwave link.

Figure 2 schematically illustrates a system 299. Said system 299 is according to one embodiment arranged in said vehicle 100.

A first control unit 200 is arranged for controlling operation of a combustion engine 230. Said combustion engine 230 may be any suitable combustion engine. Hereby said first control unit 200 is arranged for communication with said engine 230 via a link L230.

Said first control unit 200 is arranged for controlling operation of a starter 220. Said first control unit 200 is arranged for activating said starter 220. Said first control unit 200 is arranged for de-activating said starter 220. Said first control unit 200 is arranged for automatically de-activating said starter 220 according to the inventive method. Said starter 220 is arranged for, when being activated, providing torque to a flywheel 231 of said engine 230 by means of a starter gear 221. Said starter gear 221 is arranged for being selectively engaged with gears of said fly-wheel 231. Hereby said starter gear 221 is arranged to be moved between two end positions, wherein torque is being transferred to said fly-wheel 231 in one end position and no torque is being transferred to said fly-wheel 231 in said other end position. Movement of said starter gear is indicated by a bidirectional arrow in Figure 2. Said starter 220 is arranged to provide said torque to said engine 230 during a start-up phase so as to assist said engine 230 to reach a certain suitable engine speed, such as an idle speed. Said first control unit 200 is arranged for communication with said starter 220 via a link L220.

Said starter 220 is powered by an electrical power source 260. Said electrical power source 260 may be a vehicle battery providing an output voltage of e.g. 28V. Said electrical power source 260 is electrically connected to said starter 220 via a wire W260. Said first control unit 200 is arranged to control power supply to said starter by means of a switch unit 261 being arranged at said wire W260. Said first control unit 200 is arranged to control said switch unit 261 via said link L220 (which link L220 is also connected to said starter 220) so as to selectively provide electrical power to said starter 220.

An actuator means 250 is arranged for communication with said control unit 200 via a link L250. An operator of the vehicle may hereby manually start and turn off said engine 230 by means of said actuator means 250. Said actuator means may according to one example comprise a key and a key lock. Said actuator means may according to one example comprise a button for starting/turning off said engine. During a start-up phase said operator affects said actuator means 250, whereby a first start signal S250 is sent from said actuator means 250 to said first control unit 200. Upon reception of said first start signal S250 the first control unit 200 is arranged to send a second start signal 5220 to said starter 220. Said starter 220 is arranged to be activated upon reception of said second start signal 5220.

Hereby the first control unit is arranged to control said switch unit 261 so as to provide said output voltage from said electrical power source 260 to said starter 220 via said wire W260.

An engine speed sensor 270 is arranged at said fly-wheel 231. Said engine speed sensor 270 is arranged to continuously determine/detect a prevailing engine speed ENGv. Said engine speed sensor 270 is arranged for communication with said first control unit 200 via a link L270. Said engine speed sensor 270 is arranged to continuously send signals 5270 comprising information about a prevailing engine speed ENGv to said first control unit 200 via said link L270. According to an example configuration said system 299 comprises more than one engine speed sensor. According to this example one engine speed sensor may be provided at said fly-wheel 231 and another engine speed sensor may be provided at a crank shaft of said engine 230.

A temperature sensor 235 is arranged at said engine 230. Said temperature sensor 235 is arranged for communication with said first control unit 200 via a link L235. Said temperature sensor 235 is arranged to measure a prevailing temperature Temp of a coolant for cooling of said engine 235. Said temperature sensor 235 is arranged to continuously send signals S235 comprising information about said temperature Temp of said coolant to said first control unit 200 via said link L235. By comparing said prevailing temperature Temp with a predetermined temperature value said first control unit 200 may determine if the start-up phase relates to a cold start or not. If said prevailing temperature Temp is below said predetermined temperature value it is determined that the start-up phase relates to a cold start.

The first control unit 200 is arranged to perform execution of method steps and procedures described herein, e.g. with reference to descriptions of Figure 3a, Figure 3b, Figure 4a and Figure 4b.

A second control unit 210 is arranged for communication with the first control unit 200 via a link L210. It may be releasable connected to the first control unit 200. It may be a control unit external to the vehicle 100. It may be adapted to performing the innovative steps according to the invention. It may be used to cross-load software to the first control unit 200, particularly software for applying the innovative method. It may alternatively be arranged for communication with the first control unit 200 via an internal network on board the vehicle. It may be adapted to performing functions corresponding to those of the first control unit 200, such as e.g. controlling activation and de-activation of the starter according to the inventive method.

Figure 3a schematically illustrates a diagram according to an example embodiment.

Hereby a determined prevailing engine speed ENGv is presented as a function of time T. The engine speed is given in rpm and the time is given in seconds s. The engine speed is presented as a continuous line B. A determined mean slope of said determined prevailing engine speed ENGv is presented as a broken line S. Said engine speed ENGv is herein denoted engine speed course. Said engine speed course is relating to at least a segment of said determined engine speed ENGv.

The mean slope may be continuously determined in any suitable way. According to one embodiment said mean slope is determined as a time derivative of the first order. This is further depicted with reference to Figure 3b.

During a start-up phase of the engine 230 an engine speed of the engine is to be increased from zero rpm to target engine speed N. Said target engine speed N may be any suitable engine speed. According to one example said target engine speed N is 500 rpm. According to one example said target engine speed N is 800 rpm. According to one example said target engine speed N is determined to be a suitable value within the range of 500-1300 rpm. Said target engine speed N may be a predetermined engine speed. Said target engine speed may be an engine speed at which the engine generates enough power to run reasonably smoothly and operate any ancillaries of the vehicle, which may be denoted engine idle speed.

According to an example it is detected if a starting phase of said engine 230 is a so called cold start or an inertial start. A cold start relates to an engine state wherein a temperature of said engine 230 is below a certain determined temperature value. A cold start of said engine 230 is associated with higher internal friction of the engine because lubricants, such as motor oil, are more viscous at lower temperatures. An inertial start may relate to any state where it for some reasons is harder and slower to make the engine 230 to reach said target engine speed N than normally.

Herein is illustrated that it is determined if the start-up phase involves a cold start. This is determined at a first point of time Tl. According to one example said first point of time T1 may be a point of time within an interval of 0.2-0.3 seconds from start (at time T=0).

A cold start of said engine may be determined on the basis of the prevailing temperature Temp of said coolant of the engine 230. Alternatively, a cold start of said engine may be determined on the basis of a temperature relating to the surrounding air of the vehicle and a time period during which the engine has been shut off. If the engine has been shut off during at least a predetermined time period and a temperature of the surrounding air has been below a certain temperature value it may be determined that the start of the engine during the start-up phase involves a cold start.

According to one example a cold start may be determined if the mean slope of the engine speed course initially, and during a suitable time period is below a predetermined value. Said time period may be a time period of 0-T1 seconds. Said predetermined value may be e.g. 600 rpm/s, 800 rpm/s or any other value.

According to one example a cold start may be determined if the mean slope of the engine speed course initially, and during a predetermined time period, is below a predetermined value. Said time period may be a time period of 0-T1 seconds. Said predetermined value may be e.g. 600 rpm/s or 800 rpm/s.

According to one example an inertial start may be determined on the basis of an output voltage provided by said electric power source 260, which output voltage is provided so as to power said starter 220. The output voltage may be determined by any suitable means and provided to said first control unit 200. The electric power source 260 is arranged to provide a certain output voltage, e.g. 28V. If it is determined that said electric power source 260 is providing an output voltage below a predetermined output voltage value, e.g. 20V, it is determined that an inertial start is at hand. This is also depicted further with reference to Figure 3b.

In case it is determined that the start-up process is relating to a state of cold start of the engine or a state of inertial start fuel provision to said engine 230 is increased in a suitable way. This means that a larger amount of fuel is provided per time unit compared to fuel provision during so called normal conditions.

If it is determined that the start-up phase of the engine 230 relates to a state of cold start or a state of inertial start, which is determined at the time point Tl, the starter is de-activated when the engine speed ENGv has reached a predetermined engine speed, such as e.g. 450 rpm, and a predetermined time period has lapsed after the predetermined engine speed has been reached. Said predetermined time period may for example be 0.2 seconds. According to one embodiment the increased fuel injection process may be active until the predetermined target engine speed N has been reached. According to one embodiment the increased fuel injection process may be active until the predetermined target engine speed N has been reached and a predetermined time period has lapsed after said predetermined target engine speed N has been reached.

At a second point of time T2 it is predicted if a predetermined engine speed will be reached without operation of said starter 220. The prediction is performed on the basis of said determined mean slope. If it is decided that said predetermined engine speed N will be reached without operation of said starter 220, the starter 220 is de-activated. According to one example the de-activation of said starter 220 is performed at said second point of time T2. According to one example said prediction is determined on the basis of at least a portion of said engine speed course running from the time T=0 and said second point of time T2. According to one example said prediction relates to the engine speed course after the second point of time T2. According to one example a prediction process regarding if said predetermined engine speed N will be reached without operation of said starter 220 is depicted in greater detail with reference to e.g. Figure 3b.

According to one example it may be determined if the starting process involves a cold start or an inertial start at a stage after a decision regarding de-activation of said starter 220 has been taken, which de-activation decision is performed at the second point of time T2. This means that said first point of time T1 actually is a point of time later than the second point of time T2. Adequate adaptation of the described processes may be required according to one example.

At a third point of time T3 the prevailing engine speed is reaching the predetermined target engine speed N. Hereby the engine 230 is running at idle speed according to one example. According to one example definition said start-up phase is running from a time point T=0 to the third point of time T3.

The third point of time T3 is according to an example a point of time within a time interval of 0.5-3.0 seconds. The third point of time T3 is according to an example a point of time within a time interval of 0.5-2.0 seconds. The third point of time T3 is according to an example a point of time within a time interval of 0.8-1.2 seconds.

It should be noted that according to the inventive method it is possible to de-activate said starter 220 already at the second point of time T2 and still make sure that said predetermined target engine speed N is reached during prevailing conditions.

Figure 3b schematically illustrates a diagram according to an example embodiment.

Hereby a determined prevailing engine speed ENGv is presented as a function of time T. The engine speed is given in rpm and the time is given in seconds s. The engine speed is presented as a continuous line B. A determined mean slope of said determined prevailing engine speed ENGv is presented as a broken line S. Said engine speed ENGv is herein denoted engine speed course. Said engine speed course may relate to at least a segment of said determined engine speed ENGv.

The engine speed course B is hereby presented in greater detail compared to the engine speed course as of Figure 3a. It is illustrated that the engine speed course is oscillating during the start-up phase. Hereby a number of top values TV and bottom values BV become apparent. Only a subset of all top values TV and bottom values BV is indicated by reference numerals.

According to one embodiment a mean slope S of said engine speed course is determined on the basis of a number of top values TV. Said first control unit 200 is hereby arranged to continuously or intermittently determine a number of top values TV on the basis of said determined engine speed course. The first control unit 200 is hereby arranged to determine a time derivative of the first order of said engine speed course on the basis of said determined top values TP, or at least a suitable subset of said determined top values TV.

According to one embodiment a mean slope of said engine speed course is determined on the basis of a number of bottom values BV. Said first control unit 200 is hereby arranged to continuously or intermittently determine a number of bottom values BV on the basis of said determined engine speed course. The first control unit 200 is hereby arranged to determine a time derivative of the first order of said engine speed course on the basis of said determined bottom values TP, or at least a suitable subset of said determined bottom values BV.

According to one embodiment a mean slope of said engine speed course is determined on the basis of a number of mean values of successive pairs of top values TV and bottom values BV. Said first control unit 200 is hereby arranged to continuously or intermittently determine a number of mean values of successive pairs of top values TV and bottom values BV on the basis of said determined engine speed course. The first control unit 200 is hereby arranged to determine a time derivative of the first order of said engine speed course on the basis of said determined mean values, or at least a suitable subset of said determined mean values.

It should be noted that a mean slope of said engine speed course may be determined in any suitable way. However it is advantageous to determine said mean slope of said engine speed course on the basis of raw data regarding said engine speed course and thus not on the basis of any filtered data regarding said engine speed course.

According to one example it is determined if said start-up phase is relating to a cold start or an inertial start on the basis of top-to-bottom values of said engine speed course. If the amplitude of said oscillating speed course for at least a segment of said engine speed course is exceeding a predetermined value it is determined that said start-up phase is relating to a cold start or an inertial start. The segment of said engine speed course is according to an example a segment within the time period of T=0 to said first point of time T1.

According to one example embodiment the starter 220 is de-activated according to the inventive method, namely at said second point of time T2, if said mean slope of said engine speed course is exceeding a first predetermined value N1, such as 500 rpm/s, 600 rpm/s, 700 rpm/s, 800 rpm/s or any other value. If said mean slope is exceeding said first predetermined value N1 during a predetermined time interval, e.g. during any of the time intervals T=0 to T1, T=0 to T2, or T1-T2, is may be predicted that said predetermined engine speed N will be reached without operation of said starter 220 if it is de-activated at a certain point of time, such as the second point of time T2.

According to one example embodiment wherein said mean slope of said engine speed course is below a second predetermined value N2, such as 300 rpm/s, 400 rpm/s, 500 rpm/s, 600 rpm/s or any other value. If said mean slope is below said second predetermined value N2 during a predetermined time interval, e.g. during any of the time intervals T=0 to T1, T=0 to T2, or T1-T2, is may be predicted that said predetermined target engine speed N will not be reached without operation of said starter 220, and the starter 220 is hereby determined to be de-activated when the prevailing engine speed ENGv is reaching said predetermined target engine speed N.

Hereby said first predetermined value N1 is larger than said second predetermined value N2.

Figure 4a schematically illustrates a flow chart of a method for controlling operation of a starter 220 for a combustion engine 230 during a start-up phase.

The method comprises a first method step s401. The method step s401 comprises the steps of: - activating said starter 220; - continuously determining an engine speed course B of said combustion engine 230; - continuously determining a mean slope of said determined engine speed course B; - on the basis of said determined mean slope, predicting if a predetermined engine speed N will be reached without operation of said starter 220; and, - if decided that said predetermined engine speed N will be reached without operation of said starter 220, deactivating said starter 220.

After the method step s401 the method ends/is returned.

Figure 4b schematically illustrates a method for controlling operation of a starter 220 for a combustion engine 230 during a start-up phase.

The method comprises a first method step s410. The method step s410 comprises the step of activating said starter 220. This may be performed manually by an operator of the vehicle by means of said actuator means 250. Alternatively activation of said starter 220 may be performed automatically by means of said first control unit 200, e.g. when using a so called start-stop function.

After the method step s410 a subsequent method step s420 is performed.

The method step s420 comprises the step of continuously determining an engine speed course B of said combustion engine 230. This may be performed by means of said engine speed sensor 270 and said first control unit 200. After the method step s420 a subsequent method step s430 is performed.

The method step s430 comprises the step of continuously determining a mean slope of said determined engine speed course B. This may be performed in accordance with what is described with reference to e.g. Figure 3a and Figure 3b. Hereby a time derivative of the first order is determined regarding at least a portion of said determined engine speed course B. This is performed by means of said first control unit 200. After the method step s430 a subsequent method step s440 is performed.

The method step s440 comprises the step of determining if said start-up phase relates to a cold start or an inertial start. This may be performed in accordance with what is described with reference to e.g. Figure 3a and Figure 3b. This is performed by means of said first control unit 200.

If it is determined that said start-up phase relates to a cold start or an inertial start a number of measures may be taken.

According to an example one measure is to provide additional fuel for combustion to said engine 230 if a cold start has been detected.

According to an example one measure is to deactivate the starter operation after a predetermined time period when a predetermined engine speed has been reached if an inertial start has been detected.

After the method step s440 a subsequent method step s450 is performed.

The method step s450 comprises the step of on the basis of said determined mean slope, predicting if a predetermined target engine speed N will be reached without operation of said starter.

According to one example it is determined if said mean slope regarding at least a portion of said engine speed course is exceeding a first predetermined engine speed value N1. If a value of said mean slope is exceeding said first predetermined engine speed value N1 it may be predicted that said predetermined target engine speed N will be reached without operation of said starter 220. Hereby said prediction may involve a process of extrapolation. It is hereby assumed that the existing trend of said engine speed course during a relatively early segment of the start-up phase will continue.

According to one example it is determined if said mean slope regarding at least a portion of said engine speed course is below a second predetermined engine speed value N2. If a value of said mean slope is below said second predetermined engine speed value N2 it may be predicted that said predetermined target engine speed N will not be reached without further operation of said starter 220. Hereby said prediction may involve a process of extrapolation. It is hereby assumed that the existing trend of said engine speed course during a relatively early segment of the start-up phase will continue. Hereby certain measures may be taken for allowing said engine 230 to reach said predetermined target engine speed in a proper way, said measures may include e.g. provision of additional fuel to said engine 230 for combustion during said start-up phase.

By predicting that said predetermined target engine speed N will be reached, paying regard to said determined mean slope, the starter 220 may be de-activated at a relatively early stage, such as at the point of time T2. The starter is thus in this case not operating until the predetermined engine speed N has been reached. The starter may according to this example be de-activated at a suitable point of time allowing the engine to reach said predetermined engine speed N while providing safe and secure de-activation of said starter 220 regarding electricity issues of said starter 220.

After the method step s450 a subsequent method step s460 is performed.

The method step s460 comprises the step of, if decided that said predetermined engine speed will be reached without operation of said starter, deactivating said starter.

After the step s460 the method is ended/returned.

Figure 5 is a diagram of one version of a device 500. The control units 200 and 210 described with reference to Figure 2 may in one version comprise the device 500. The device 500 comprises a non-volatile memory 520, a data processing unit 510 and a read/write memory 550. The non-volatile memory 520 has a first memory element 530 in which a computer program, e.g. an operating system, is stored for controlling the function of the device 500. The device 500 further comprises a bus controller, a serial communication port, I/O means, an A/D converter, a time and date input and transfer unit, an event counter and an interruption controller (not depicted). The non-volatile memory 520 has also a second memory element 540.

The computer program P comprises routines for controlling operation of a starter 220 for a combustion engine 230 during a start-up phase.

The computer program P may comprise routines for activating said starter 220.

The computer program P may comprise routines for continuously determining an engine speed course B of said combustion engine 230.

The computer program P may comprise routines for continuously determining a mean slope of said determined engine speed course.

The computer program P may comprise routines for, on the basis of said determined mean slope, predicting if a predetermined engine speed N will be reached without operation of said starter 220.

The computer program P may comprise routines for, if decided that said predetermined engine speed N will be reached without operation of said starter 220, deactivating said starter 220.

The computer program P may comprise routines for deciding that said predetermined engine speed N will be reached without operation of said starter 220 when a mean slope of said determined engine speed course B exceeding a first predetermined value, such as e.g. 800 rpm/s, is detected.

The computer program P may comprise routines for providing additional fuel for combustion to said engine 230 if a mean slope of said determined engine speed course B is below a second predetermined value, such as e.g. 600 rpm/s.

The computer program P may comprise routines for, in case of an inertial start or a cold start of said engine, deactivating said starter 220 when an idle engine speed of said engine 230 is detected.

The computer program P may comprise routines for determining an output voltage of a starter battery 260.

The computer program P may comprise routines for, if said output voltage is below a predetermined value, deactivating the starter 220 operation after a predetermined time period when a predetermined engine speed is reached.

The computer program P may comprise routines for performing any of the process steps detailed with reference to Figure 4b.

The program P may be stored in an executable form or in compressed form in a memory 560 and/or in a read/write memory 550.

Where it is stated that the data processing unit 510 performs a certain function, it means that it conducts a certain part of the program which is stored in the memory 560 or a certain part of the program which is stored in the read/write memory 550.

The data processing device 510 can communicate with a data port 599 via a data bus 515. The non-volatile memory 520 is intended for communication with the data processing unit 510 via a data bus 512. The separate memory 560 is intended to communicate with the data processing unit via a data bus 511. The read/write memory 550 is arranged to communicate with the data processing unit 510 via a data bus 514. The links L210, L220, L230, L235, L250 and L270 for example, may be connected to the data port 599 (see Fig. 2).

When data are received on the data port 599, they are stored temporarily in the second memory element 540. When input data received have been temporarily stored, the data processing unit 510 will be prepared to conduct code execution as described above.

Parts of the methods herein described may be conducted by the device 500 by means of the data processing unit 510 which runs the program stored in the memory 560 or the read/write memory 550. When the device 500 runs the program, method steps and process steps herein described are executed.

The foregoing description of the preferred embodiments of the present invention is provided for illustrative and descriptive purposes. It is not intended to be exhaustive, nor to limit the invention to the variants described. Many modifications and variations will obviously suggest themselves to one skilled in the art. The embodiments have been chosen and described in order to best explain the principles of the invention and their practical applications and thereby make it possible for one skilled in the art to understand the invention for different embodiments and with the various modifications appropriate to the intended use.

The components and features specified above may within the framework of the invention be combined between different embodiments specified.

Claims

1. A method for controlling operation of a starter (220) for a combustion engine (230) during a start-up phase, comprising the steps of: - activating (s410) said starter (220); - continuously determining (s420) an engine speed course (B) of said combustion engine (230); - continuously determining (s430) a mean slope (S) of said determined engine speed course (B); - on the basis of said determined mean slope (S), predicting (s450) if a predetermined engine speed (N) will be reached without operation of said starter (220); and, - if decided that said predetermined engine speed (N) will be reached without operation of said starter (220), deactivating (s460) said starter (220), the method characterized by - determining an output voltage of a starter battery (260); - if said output voltage is below a predetermined value, deactivating the starter operation after a predetermined time period when a predetermined engine speed (N) is reached.

2. The method according to claim 1, comprising the step of: - deciding that said predetermined engine speed (N) will be reached without operation of said starter (220) when a mean slope (S) of said determined engine speed course (B) exceeding a first predetermined value (N1) is detected.

3. The method according to claim 1 or 2, comprising the steps of: - providing additional fuel for combustion to said engine (230) if a mean slope (S) of said determined engine speed course (B) is below a second predetermined value (N2), wherein said first predetermined value (N1) is larger than said second predetermined value (N2); and - deactivating said starter (220) when an idle engine speed of said engine (230) is detected.

4. A system for controlling operation of a starter (220) for a combustion engine (230) during a start-up phase, comprising: - means (200; 210; 500; 250) arranged for activating said starter (220); - means (200; 210; 500; 270) arranged for continuously determining an engine speed course (B) of said combustion engine (230); - means (200; 210; 500) arranged for continuously determining a mean slope (S) of said determined engine speed course (B); - means (200; 210; 500) arranged for, on the basis of said determined mean slope (S), predicting if a predetermined engine speed (N) will be reached without operation of said starter (220); and, - means (200; 210; 500) arranged for, if decided that said predetermined engine speed (N) will be reached without operation of said starter (220), deactivating said starter (220), the system characterized by - means (200; 210; 500) arranged for determining an output voltage of a starter battery (260); - means (200; 210; 500) arranged for, if said output voltage is below a predetermined value, deactivating the starter operation after a predetermined time period when a predetermined engine speed (N) is reached.

5. The system according to claim 4, comprising: - means (200; 210; 500) arranged for deciding that said predetermined engine speed (N) will be reached without operation of said starter (220) when a mean slope (S) of said determined engine speed course (B) exceeding a first predetermined value (N1) is detected.

6. The system according to claim 4 or 5, comprising: - means (200; 210; 500) arranged for providing additional fuel for combustion to said engine (230) if a mean slope of said determined engine speed course is below a second predetermined value (N2), wherein said first predetermined value (N1) is larger than said second predetermined value (N2); and - means (200; 210; 500) arranged for deactivating said starter (220) when an idle engine speed of said engine (230) is detected.

7. A vehicle (100; 110) comprising a system according to anyone of claims 4-6.

8. The vehicle (100; 110) according to claim 7, which vehicle is any from among a truck, bus or passenger car.

9. A computer program (P) for controlling operation of a starter (220) for a combustion engine (230) during a start-up phase, wherein said computer program (P) comprises program code for causing an electronic control unit (200; 500) or a computer (210; 500) connected to the electronic control unit (200; 500) to perform the steps according to any of the claims 1-3.

10. A computer program product containing a program code stored on a computer-readable medium for performing method steps according to any of claims 1-3, when said computer program is run on an electronic control unit (200; 500) or a computer (210; 500) connected to the electronic control unit (200; 500).