PROCESS OF DETERMINATION OF THE POSITION ENGINE AND CORRESPONDING DEVICE

The present invention relates to a method for determining the motor position and a corresponding device. More particularly, it is synchronize a control computer of the engine to the actual engine cycle as soon as the rotation of the crankshaft.

An internal combustion engine generally includes a motor shaft called crankshaft rotated by the movement of pistons each associated with a cylinder.

A second shaft, called camshaft, is loaded open and close the exhaust and inlet valves of each cylinder for introducing a mixture for explosion or for the exhaust of burned gases.

Of course, for the engine operates optimally, it is of the utmost importance that these two shafts synchronized.

This synchronization, between the camshaft and the crankshaft, is carried out mechanically and will not be detailed herein because it is well known.

The control computer engine utilizes a calculation algorithm that should, also, be synchronized with the real cycle of the engine to operate effectively.

The second timing also known as "software synchronization" is to be performed at each time the engine is resumed. This synchronization involves arranging for the engine cycle or in correspondence with the algorithm of the control computer of the engine.

The present invention relates to this second timing (software synchronization).

To this end, a target gear having a singularity (for example on 60 teeth distributed uniformly over the circumference of the target, two consecutive teeth are missing (singularity also known as long teeth)) is rotated integrally with the crankshaft. Target A each revolution of the crankshaft, the latter passes a suitable sensor which emits a signal tooth to a computer. Teeth After analysis of this signal, the computer generates a signal having a singularity at each passage of the long crankshaft tooth past the sensor. This is used to identify a predetermined position on the crankshaft.

Correspondingly, and also known per se, the camshaft is provided with a target. The target is rotated with the camshaft and has two levels (a low level and a high level). When the target camshaft is rotated, a suitable sensor detects each time if it is in front of the high level or low level.

In a known manner, the crankshaft and the camshaft are interconnected in such a manner that each time the camshaft makes one rotation, the crankshaft in fact two.

Therefore, each time the crankshaft singularity is detected, it is determined what is the level (low or high) of the target camshaft on the opposite side of the camshaft sensor.

It is then determined according to the level of the camshaft signal (high or low) in which position the motor at the time of the passage of the singularity crankshaft. However, with the devices known in the art, the exact determination of the motor position is acquired by worse than at the end of 360° crankshaft (i.e. one turn crankshaft).

This time is judged too long and it is desired to provide a method (and a device) for determining the motor position that is faster, without however requiring the use of additional sensors.

To this end, the present invention relates to a method for determining the phase of each of the cylinders of an internal combustion engine, said engine having a crank shaft integral in rotation with a toothed target associated with a sensor generating a signal representative of the teeth of the target, a calculator is adapted to analyse the signal teeth and generating a signal having singularities crankshaft, and a camshaft which is fixed in rotation to a target camshaft associated with a sensor that generates a signal representative of the level of the target, said method being characterized in that it uses a crankshaft having at least two target singularities, and in that it consists in:

-monitoring the occurrence of a transition of the camshaft signal, as soon as the rotation of the crankshaft,

-detecting the occurrence of a singularity on the signal crankshaft,

-determine if the singularity has been preceded of teeth for a period determined by a signal transition camshaft and,

-deducing the phase in which is each of the cylinders of the engine by taking into account the level of the signal from the target camshaft timing and the presence or absence of a transition of the camshaft signal, during the interval of teeth determined.

Therefore, upon first detection of a feature, it is possible to determine to be accurately and precisely the position of each of the cylinders in the engine cycle (intake, compression, explosion, exhaust). The first detection of a singularity is carried out (in the worst case), 180° after rotating the crankshaft and non 360° after, as was the case in the art. Subsequently the synchronisation is faster without additional sensor is required. The use of a target crankshaft having at least two singularities is still.

According to the invention, by taking into account both the occurrence of a transition on the signal camshaft in a predetermined time prior to detection of a feature on the crankshaft signal, and the level of said signal, it is possible to accurately judge which cylinder will be compressed after the singularity. Therefore, it is possible to supply properly such cylinder and cause explosion of the mixture that it contains timely.

Advantageously, the tooth spacing (during which monitors whether a signal transition camshaft occurred), prior to detecting signal of a feature on the crankshaft, is centered on a signal transition camshaft a stroke on two.

The present invention also relates to a device for implementing the method according to the invention.

Other objects, features and advantages of the present invention, shall become apparent also of the description that follows, by way of non-limiting example, and with reference to the accompanying drawings in which:

Figure 1a-, represents, schematically, the signal camshaft during one turn of the shaft,

Figure 1b-, is a schematic view representing the signal crankshaft, during one rotation of the camshaft,

Figure 1c-, shows a schematic of the TDC (Points Morts Hauts) of each of the cylinders of a four-cylinder engine, during a turn of camshaft,

Figure 1d-, represents the pairs of values (T, N) according to the invention, at the time of each detection signal of singularity of the crankshaft, and

Figure 2- , is a schematic view representing the different means used in the method according to the present invention.

The present invention is explained below by taking as an example an internal combustion engine having four cylinders.

However, the invention could be applied to an internal combustion engine having a different number of cylinders.

In a way known per se, the internal combustion engine to which is applied the present invention has four cylinders arbitrarily referenced C1 to C4 (Figure 1c). Each of the cylinder is associated with the drive axle or crankshaft so as to cause rotation thereof.

Each of the cylinder has at least one intake valve and an exhaust valve. These valves are adapted to admit to the interior of the cylinder the combustion mixture, and for out the mixture when the combustion has taken place.

The displacement of the valves is managed by a camshaft 10 (Figure 2) in a known manner (and not detailed herein).

The drive shaft 11 (crankshaft) and the camshaft are provided with toothed target 12, 14.

The target camshaft 12 (Figure 2) has two sectors: a sector of high level H, and a sector low level sensor 13 B. A camshaft is adapted to detect the passage of each of these sectors in front of it. AAC The signal generated by the sensor is shown in Figure 1a. As noted, the first signal has a high level (H) (in the example shown) during one turn of the crankshaft (360°), and a low level (B) tower also during a crankshaft.

The target crankshaft 14, itself has two singularities (long teeth) on its periphery. A crankshaft sensor 15 is adapted to detect the passage of teeth of the target and to generate a signal tooth S sent to a computer 16. The computer system analyzes the sensor signal and derives the presence of long teeth (or singularities) I. The signal analyzed by the computer is represented in Figure 1b (Vil signal). As may be noted on each revolution of the crankshaft, the signal has singularities Vil

(I). Since the crankshaft rotates two times faster than the camshaft, four include singularities (I) (long teeth) during one revolution of the camshaft (or during 720° crankshaft).

It is understood that the two target singularities of the crankshaft are arranged one opposite the other, i.e. 180°.

The aim of the invention is to accurately assess the phase in which is each cylinder upon the occurrence of the first crankshaft singularity.

In a known manner, a fixed angular offset exists between the time when a singularity (I) is detected and when one of the cylinders is in compression. The offset is for example attached to 90 ° (case shown in Figure 1c).

In the prior art, the target crankshaft were that a singularity. When a singularity was detected, it was necessary to wait at worst 360° for synchronization.

In contrast in the present invention, there are two singularities per revolution crankshaft. Furthermore, according to the invention, each time a singularity is detected, it is checked whether in a tooth spacing t determined (generally eight teeth-schematized in shaded area in Figure 1a-) before the pulse, there has been a transition of the camshaft signal (Figures 1a and 1b). Therefore, it is checked in each shaded area in Figure 1a if there is or there has been no signal transition T of the camshaft. Transition When there has been (or a high to a low, or a low level to a high level), the value of T is 1. If there has been no transition, the value of T is zero (see Figure 1d). Simultaneously, it is checked for each singularity (I) signal detected the state of the camshaft at that time. Either the signal is at a low level and the level N is B, or it is at a high level and the level N is H.

Therefore, at each singularity (I), it is possible to link a unique pair of values (T, N) (Figures 1d and 2)

In the example represented, the first corresponds to a singularity torque (T, N) value (1, H) respectively. Or, the value indicates that it is the listed 1 cylinder which is in compression after the singularity 90°.

Each of the cylinders has a torque (T, N) single. Thus (Figure 1d):

-whether the torque (T, N) is equal to (1, H), the cylinder 1 will be in compression,

-whether the torque (T, N) is equal to (0, H), the cylinder 2 will be in compression

-whether the torque (T, N) is equal to (1, B), the cylinder 3 will be in compression, and

-whether the torque (T, N) is equal to (0, B), the cylinder 4 will be in compression.

Therefore, as soon as the torque (T, N) is known, it is possible to know with accuracy the phase of each cylinder of the engine during the engine cycle and thus send a synchronization signal to the computer 17 Syn (ECU-Electronic Control Unit) motor control.

The determination of this phase is rapid since, in the worst case, it takes only 180° to be acquired.

Thus taking into account when each singularity

(I) detected:

-of the occurrence of a transition (T) signal of the camshaft in a range preceding the singularity t detected and,

-level signal (N) of the camshaft at the time of the singularity,

accurately determine the phase of each cylinder.

Preferably, the tooth spacing (t) during which it is checked whether a signal transition on the camshaft is centered on a transition on two such a shot. Indeed, as seen in Figures 1a and 1b, a singularities (I) is attached shortly after a transition and following singularity occurs in the middle of a high or low level signal for the camshaft. The interval (t) is therefore time at the time of a transition t.

The invention also relates to a device for implementing the method described above.

The target crankshaft 14 according to the invention has at least two singularities (long teeth). The target camshaft can have more than two transitions, but only two of these transitions are required for the present invention. In fact, the target camshaft must have at least two transitions and two distinct stable levels in corresponding windows to the interval t. Outside these windows, the target camshaft can have any configuration.

The device according to the present invention comprises, in addition to the target camshaft and crankshaft and their associated sensors (13, 15), a unit 16 for determining the phase in which there is in each engine cylinder. The unit takes into account the occurrence of a transition (T) of the camshaft signal occurrence during an interval of teeth (t) previously determined the occurrence of a feature (I) signal of the crankshaft, and the level (N) signal of the camshaft at the time of occurrence of the singularity. The unit 16 then derives torque information (T, N) the position of the motor (the phase of each of the cylinders at the time of the singularity (I)) and outputs a timing signal to the computer 17 Syn to synchronize the calculation algorithm content into this computer 17 with the actual engine cycle.

It should be noted that according to the invention, for each of the singularities detected (I) is associated with a single torque (T, N) values representative of the phase of each cylinder.

Of course the present invention is not limited to the embodiment described above and includes variant within the reach of the skilled in the art. In particular, the number of cylinders of the engine may be different from four.

Indeed, in the case of an engine of more than four cylinders, one always obtains an synchronization algorithm computation on the engine cycle at the end of 180° crankshaft. The present invention is independent of the number of cylinders of the engine.

In the case of a four-cylinder engine, this synchronization is always performed before a TDC (top dead center). In the case of an engine of more than four cylinders, this synchronization is not always performed before a TDC (which is hardly disturbing) but still at the end of 180° crankshaft.

In a known manner, the angle values indicated (180° and 360° crankshaft) are not fair values. Indeed, if eight teeth (conventional value, but not required) to the computer are required to be sure that the crankshaft is rotating, these values of 180° and 360° can be hit +66 uncertainty; the synchronization according to the present invention taking place at worst after 246 °, while previously it had been broadcasted at worst after 426°.