CN108350813B

CN108350813B - Method for controlling the starting of an engine comprising a warm-up phase and a torque generation phase

Info

Publication number: CN108350813B
Application number: CN201680069335.6A
Authority: CN
Inventors: C.库尔蒂; L.勒-布鲁斯蒂; P.塞雷基亚
Original assignee: Continental Automotive GmbH; Continental Automotive France SAS
Current assignee: Vitesco Technologies GmbH
Priority date: 2015-11-26
Filing date: 2016-11-18
Publication date: 2021-10-29
Anticipated expiration: 2036-11-18
Also published as: BR112018010512A8; WO2017088967A1; FR3044362A1; FR3044362B1; CN108350813A; BR112018010512A2

Abstract

A control method (10) for the starting of a combustion engine comprising at least one cylinder, a combustion cycle sensor and a counter, comprising: -a fuel pressure increasing step (105) by means of a first combustion mode, -a temperature increasing step (110) by means of a second combustion mode and which comprises at least one combustion cycle, -a combustion cycle detecting step (115) which detects a successful combustion cycle by means of a combustion cycle sensor and which is registered by means of a counter, repeating steps (110) and (115) until the number of combustion cycles registered by the counter equals a predetermined value, and-a torque generating step (120) by means of a third combustion mode.

Description

Method for controlling the starting of an engine comprising a warm-up phase and a torque generation phase

Technical Field

The present invention is directed to a control method for starting a combustion engine. The invention is applicable to gasoline, ethanol engines or engines using a mixture of gasoline and ethanol.

For direct injection engines, the invention is particularly advantageously applied in the combustion mode during the engine start phase.

Background

For starting an engine comprising an injection, it is known from the prior art to use a specific combustion mode for the start. This particular combustion mode controls a set of parameters that are different from the operating parameters of the engine during normal operation.

It is known from the prior art to start a switch from a specific combustion mode for start-up to a combustion mode dedicated to normal operation of the engine when an engine speed threshold is reached or a predetermined time interval has been reached since the engine started running.

A disadvantage of this system is that the management of the switching from a specific combustion mode for starting to a combustion mode dedicated to the normal operation of the vehicle needs to be calibrated on the basis of what is considered to be the worst case system.

In fact, the combustion mode dedicated to the starting of the vehicle is not vehicle-specific and does not allow to compensate for the variability between vehicles, for example due to system ageing, production dispersion or even the characteristics of the fuel used.

Thus, variability between vehicles may result in extended engine start times and even failed starts.

Any current system does not allow to meet all the needs simultaneously, i.e. to ensure a start in exactly the required and reliable time, regardless of the variability due to the vehicle and to the fuel used.

Disclosure of Invention

The present invention aims to overcome all or some of these disadvantages.

To this end, according to a first aspect, the invention is directed to a control method for the start of a combustion engine comprising at least one cylinder, a combustion cycle sensor and a counter, the control method comprising:

the fuel pressure increasing step by means of the first combustion mode,

a temperature increasing step by means of a second combustion mode and which comprises at least one combustion cycle,

a combustion cycle detection step of detecting a successful combustion cycle by means of a combustion cycle sensor and recording by means of a counter,

repeating the temperature-raising step and the combustion-cycle detecting step until the number of combustion cycles recorded by the counter becomes equal to a predetermined value, an

A torque generating step by means of a third combustion mode.

By means of these arrangements, the starting sequence of an engine comprising injections is divided into successive phases comprising at least three combustion modes. In each combustion mode, engine parameters such as ignition, throttle position, number of fuel injections, and frequency of fuel injections are controlled. The combustion cycle sensor allows for detection of a successful combustion cycle.

Each successful combustion cycle is recorded by a counter. When the number of successful combustion cycles recorded by the counter is greater than a predetermined value, a switch is performed from a second combustion mode to a third combustion mode, wherein the second combustion mode is configured to facilitate a temperature increase in the engine and the third combustion mode is configured to facilitate engine torque production.

These settings allow the engine to maintain the second combustion mode for the proper time required on each system. The method object of the invention thus allows starting a combustion engine without an excessive time and with a reduced risk of starting faults.

In other words, the target method of the present invention is robust against starts, especially for critical starts, e.g. at low temperatures. The method object of the invention is particularly suitable for starting ethanol engines at low temperatures and for starting engines supplied with gasoline or mixed fuels at very low temperatures.

The method object of the present invention differs from the prior art in particular in that it allows to initiate a switch from the first combustion mode to the second combustion mode without generating torque and therefore without generating a rotation speed on the basis of the number of combustion cycles performed.

In some embodiments, the target method of the present invention comprises, after the torque generating step:

decelerating and operating normally the engine by means of the fourth combustion mode.

In some embodiments, the first combustion mode does not include gasoline injection.

In some embodiments, the fuel pressure increasing step by way of the first combustion mode further comprises reducing pressure in the manifold by way of closing of a throttle.

With these arrangements, the fuel pressure can be increased during the pressure increasing step. Moreover, the features of the first combustion mode allow for a reduction in the volume of air contained in the cylinder. Reducing the mass of air contained in the cylinder by means of the first combustion mode allows a sufficient amount of fuel to evaporate to initiate a start.

In some embodiments, the parameters manipulated in the second combustion mode are ignition, throttle position, number of fuel injections, and frequency of fuel injections.

With these arrangements, the second combustion mode allows for an increase in temperature in at least one cylinder.

In some embodiments, the parameters manipulated in the third combustion mode are ignition, throttle position, number of fuel injections, and fuel injection frequency.

A third combustion mode, which promotes torque production, is known in the art, i.e. it comprises, in particular, the opening of a throttle, the increase of the injected fuel mass and a spark advance which allows an optimum torque to be obtained.

With these settings, the third combustion mode allows engine torque to be generated.

In some embodiments, the combustion cycle sensor is a tooth signal sensor.

Due to these settings, the angular position of the crankshaft is determined. The sensor measures a signal indicative of an angular position of the crankshaft. The predetermined value of the angular position of the crankshaft corresponds to a top dead center position. The cylinder pressure sensor allows determining when the cylinder is at top dead center and thus allows detecting the combustion cycle of the cylinder.

Advantageously, the tooth signal sensor allows the method of the invention to be implemented in an inexpensive manner. In practice, the tooth signal sensors are mounted in series on the model over most of the cycle.

In some embodiments, the combustion cycle sensor is a knock sensor.

Due to these arrangements, the sensor measures the vibrations emitted by the cylinder. The vibrations emitted by the cylinder are data representative of the piston position, which allows determining when the cylinder is at top dead center and thus detecting the combustion cycle of the cylinder.

In some embodiments, the combustion cycle sensor is a cylinder pressure sensor.

Due to these arrangements, the pressure in at least one cylinder is measured during a combustion cycle. The measured pressure is data indicative of cylinder position and it allows a determination of when the combustion cycle is operating correctly. The cylinder pressure sensor allows determining when the cylinder is at top dead center and thus detecting the combustion cycle of the cylinder.

Advantageously, the cylinder pressure sensor allows for accurate and real-time measurement of pressure, thereby allowing for accurate determination of the occurrence of a combustion cycle and quantification of the energy produced by the combustion.

According to a second aspect, the invention is directed to a device for implementing the method of control of the start of a combustion engine comprising at least one cylinder, a combustion cycle sensor and a counter implementing the method of the object of the invention.

Since the objects, advantages and specific features of the device are similar to those of the object method of the present invention, they will not be described in detail herein.

Drawings

Further advantages, objects and specific features of the invention will emerge from the following non-limiting description of at least one particular embodiment of the subject device, method and system of the invention, with reference to the attached drawings, in which:

figure 1 shows an embodiment of the target method of the invention in the form of a flow chart,

figure 2 shows an embodiment of the target method of the invention in the form of a graph of engine rotational speed over time,

figure 3 shows in a graph the variation of the temperature inside the cylinder with the angular position of the crankshaft at an absolute pressure of 1 bar,

FIG. 4 shows, in a graph, the temperature in the cylinder as a function of the angular position of the crankshaft at an absolute pressure of 0.3 bar, and

fig. 5 schematically shows in a cross-sectional view a particular embodiment of a device for implementing the method object of the invention.

Detailed Description

The present description has been described in a non-limiting manner, and each feature of one embodiment can be combined in an advantageous manner with any other feature of any other embodiment.

It is noted that the drawings are not to scale.

In fig. 1, it can be observed a control method 10 for the start of a combustion engine, comprising at least one cylinder, a combustion cycle sensor and a counter, comprising:

by means of the fuel pressure increasing step 105 of the first combustion mode,

a temperature increasing step 110 by means of a second combustion mode and comprising at least one combustion cycle,

a combustion cycle detection step 115 of detecting a successful combustion cycle by the combustion cycle sensor and recording it by a counter,

repeating steps

110 and 115 until the number of combustion cycles recorded by the counter equals a predetermined value, an

A torque generating step 120 by means of a third combustion mode.

In other words, the target method of the present invention breaks down the start of the engine including injection into different phases. These phases are each realized by means of a specific combustion mode.

The combustion mode refers to all controlled characteristics during the engine operating phase. The controlled characteristics include ignition, throttle position, number of fuel injections, location of injection in the combustion cycle, amount of each injection, and pressure of the injected fuel.

During the pressure increasing step 105, the fuel pressure is increased by means of the first combustion mode.

In some embodiments, the fuel pressure increasing step 105 by way of the first combustion mode further comprises reducing the pressure in the manifold by way of closing of a throttle.

Closing of the throttle valve allows blocking of the air inlet and thus reducing the amount of air in the cylinder.

In some embodiments, the pressure is increased to about eighty bar.

In some preferred embodiments, the first combustion mode does not include gasoline injection.

During step 105, the amount of air taken into the cylinder is reduced, this arrangement allowing the evaporation of the sprayed gasoline to be promoted during the temperature increase step 110.

During the temperature increasing step 110, the temperature in at least one cylinder is increased by means of the second combustion mode.

In some preferred embodiments, the parameters manipulated in the second combustion mode are ignition, throttle position, number of fuel injections, and fuel injection frequency.

The second combustion mode is configured to produce a temperature increase without producing engine torque.

During step 115, the combustion cycle sensor detects a successful combustion cycle. Each successful combustion cycle is counted by a counter. The temperature increase step 110 and the detect and record successful combustion cycle step 115 are repeated as many times as necessary so that the counter reaches a predetermined number of successful combustion cycles.

In some embodiments, the combustion cycle sensor is a tooth signal sensor.

The tooth signal sensor measures a signal indicative of an angular position of the crankshaft. The predetermined value of the angular position of the crankshaft corresponds to a top dead center position.

In some embodiments, the combustion cycle sensor is a knock (cliquetis) sensor. In some embodiments, the knock sensor is a piezoelectric sensor and the measured signal is data representative of piston position, which allows determining when the cylinder is at top dead center and thus detecting the combustion cycle of the cylinder.

In some preferred embodiments, the combustion cycle sensor is a cylinder pressure sensor. During a combustion cycle, a cylinder pressure sensor measures pressure in at least one cylinder. The measured pressure is data representing the cylinder position. The cylinder pressure sensor allows determining when the cylinder is at top dead center and thus detecting the combustion cycle of the cylinder.

In some embodiments, the pressure values measured by the cylinder pressure sensors are compared to a reference curve. Since the value of the pressure in the cylinder is known for cycles with fuel combustion and also for cycles without combustion, comparing these reference values with the values measured by the cylinder pressure sensor allows determining when a cylinder cycle has been achieved with fuel combustion.

In some embodiments, the temperature is measured by means of a temperature sensor. In some embodiments, the switch from step 110 to step 115 is performed when the temperature measured in the cylinder is greater than or equal to a predetermined value.

In some embodiments, the switch from step 115 to step 120 is performed when the temperature is greater than or equal to a predetermined threshold and the number of successful combustion cycles recorded by the counter is greater than or equal to a predetermined value.

In some embodiments, the temperature is measured in the cylinder. Preferably, the sensors provided in the method of the invention are sensors capable of measuring the temperature and pressure in the cylinder.

In other embodiments, at least one temperature sensor is positioned on the cylinder wall. In other embodiments, the temperature sensor is disposed at the exhaust.

During the torque producing step 120, engine torque is produced by means of the third combustion mode. The third combustion mode is configured to produce engine torque and increase engine revolutions per minute.

In some embodiments, the controlled characteristics include ignition, throttle position, number of fuel injections, location of injection during a combustion cycle, amount of each injection, and pressure of the injected fuel.

In some embodiments, the method 10 includes, after the torque generating step 120:

step 125 of decelerating and operating the engine normally by means of the fourth combustion mode.

Step 125 corresponds to leaving the engine start phase to run the engine under normal operating conditions.

A curve representing in the form of a curve a specific example of a course of a control method for starting a combustion engine which achieves the object of the invention can be observed in fig. 2. The graph shows engine speed (in revolutions per minute) as a function of time (in units of time). In some preferred embodiments, the speed of the engine is substantially steady during

steps

105 and 110, increasing the pressure and increasing the temperature, respectively.

In some embodiments, during the torque generating step 120, the speed of the engine is increased until a predetermined speed value is reached. When the speed of the engine is greater than or equal to the predetermined speed, a switch is performed from the torque generation step 120 to a step 125 of decelerating and normally operating the engine.

In other embodiments, the switch from torque generation step 120 to engine retard and normal operation step 125 is performed when the absolute value of the rotational speed is exceeded.

The variation of the temperature in the cylinder with the angular position of the crankshaft in the form of a graph in the target method of the invention is observed in fig. 3 and 4.

Fig. 3 and 4 show the temperature (expressed in degrees kelvin and plotted on the ordinate 160) as a function of the angular position of the crankshaft (plotted on the abscissa 165).

The fuel used in the methods shown in fig. 3 and 4 is pure ethanol, also known as E100. A curve a of the fuel evaporation temperature can be observed in fig. 3 and 4.

Two curves B and C corresponding to in-cylinder temperatures for two different configurations of the combustion cycle can also be observed. Curve B corresponds to the temperature of the air contained in the cylinder in the presence of fuel evaporation, while curve C corresponds to the temperature of the air contained in the cylinder in the absence of fuel evaporation.

The cylinder temperature shown by curves B and C should be greater than the fuel vaporization temperature used to allow fuel to vaporize. The angular range favorable for fuel injection is defined as the interval of the curve B in which the vaporization temperature of the fuel is less than the cylinder temperature.

The combustion cycle shown in figure 3 is at 0.3 bar absolute.

The combustion cycle shown in fig. 4 is at 1 bar absolute and includes the throttle valve in a closed position, which facilitates pressure increase.

It is observed that the conditions set in fig. 4, in which the throttle is in the closed position, allow the occurrence of a range of angles favouring fuel injection, the limits of which, at angles of-39 ° and 22 °, are represented by the two vertical dashed

lines

180 and 185, respectively.

The arrangement achieved by the method of the invention shown in fig. 5 therefore promotes a greater angular range in favour of fuel injection.

In fig. 5, a device 20 of a control method 10 for the starting of a combustion engine for implementing the method object of the present invention can be seen, which device 20 comprises at least one cylinder 205, a combustion cycle sensor 210 and a counter 215.

The apparatus 20 also includes an injector 260, an air inlet 265, and an exhaust outlet 270.

In some preferred embodiments, the counter 215 is integrated into the processor 225.

In some embodiments, the apparatus 20 includes at least one of the following sensors: a tooth signal sensor 230, a knock sensor 235, a cylinder pressure sensor 240, and a temperature sensor 250.

In some embodiments, processor 225 collects and processes data measured by at least one sensor. The processing of the data may include one or more mathematical calculations or the implementation of an algorithm.

In other words, processor 225 may be referred to as an engine control unit.

In some embodiments, processor 225 compares the data measured by the sensors to predetermined values stored in memory 220.

In some embodiments, processor 225 determines a secondary value from the primary value measured by the sensor. In some embodiments, the position of the piston 255 in the cylinder 205 is determined by the processor from at least one data measured by at least one sensor.

In some embodiments, at least one data recorded by at least one of the

sensors

210, 230, 235, 240, 250 is recorded in the memory 220.

Claims

1. A control method (10) for the starting of a combustion engine comprising at least one cylinder, a combustion cycle sensor and a counter, characterized in that it comprises:

a fuel pressure increasing step (105) by means of the first combustion mode,

a temperature increasing step (110) by means of a second combustion mode and which comprises at least one combustion cycle,

a combustion cycle detection step (115) of detecting a successful combustion cycle by means of a combustion cycle sensor and recording by means of a counter,

repeating the temperature increasing step (110) and the combustion cycle detecting step (115) until the number of combustion cycles recorded by the counter equals a predetermined value, an

A torque generating step (120) by means of a third combustion mode, the first combustion mode being configured to increase fuel pressure, the second combustion mode being configured to generate a temperature increase, the third combustion mode being configured to generate an engine torque.

2. The method (10) of claim 1, comprising, after the torque generating step (120):

-decelerating and running normally (125) the engine by means of the fourth combustion mode.

3. The method (10) of claim 1, wherein the first combustion mode does not include gasoline injection.

4. A method (10) according to any of claims 1-3, wherein the fuel pressure increasing step (105) by means of the first combustion mode further comprises reducing the pressure in the manifold by means of the closing of a throttle valve.

5. A method (10) according to any of claims 1-3, wherein the controlled characteristics in the second combustion mode include ignition, throttle position, number of fuel injections, injection position in the combustion cycle, amount per injection and pressure of injected fuel.

6. The method (10) of any of claims 1-3, wherein the controlled characteristics in the third combustion mode include ignition, throttle position, number of fuel injections, injection location in a combustion cycle, amount of each injection, and pressure of injected fuel.

7. The method (10) according to any one of claims 1-3, wherein the combustion cycle sensor is a tooth signal sensor.

8. A method (10) according to any of claims 1-3, wherein the combustion cycle sensor is a knock sensor.

9. A method (10) according to any of claims 1-3, wherein the combustion cycle sensor is a cylinder pressure sensor.

10. An apparatus (20) for implementing a control method (10) for the start of a combustion engine according to any one of claims 1 to 9, characterized in that said apparatus (20) comprises at least one cylinder (205), a combustion cycle sensor (210) and a counter (215).