EP0225528B1 - Angular pulses identifying arrangement - Google Patents

Abstract

A timing arrangement incorporates a timing disk having absolute marks arranged about a circle and serving for the identification of the angular position of the shaft of an internal combustion engine. The marks include a code track havig code marks and absolute marks, each absolute marks being preceded by a code element comprising a number of code marks. Each absolute mark is identified by a code section preceding and consisting of two or more code elements.

Description

The invention relates to an arrangement according to the preamble of claim 1.

Such an arrangement is known from US Pat. No. 4,284,052. An electronic control unit is described there, which - in particular in connection with a microprocessor - determines the start of fuel injection and / or ignition. As a basis for the calculation, this control unit needs information about the current status of the crankshaft coupled to the individual cylinders. This is therefore coupled to an encoder arrangement in the form of an encoder disk, which has angular marks on its circumference, which are scanned by an impulse transmitter which delivers an angular pulse for each angular mark.

In order to assign the angle mark that caused this angle pulse to a single angle pulse, it is necessary to assign at least one of the angle pulses (absolute pulse) a defined position of the shaft with respect to a fixed point by means of an additional identity identifier. In the known case, a code element is arranged in front of each angle mark, the identity identifier of which is the number of code marks contained in it. The code marks are also scanned by the pulse generator and generate a code pulse. Each angular pulse is therefore determined by the number of preceding code pulses.

The largest number of code marks per code element and thus the length of the largest code element is determined by the number of angle marks to be distinguished: It has been shown that it is not possible to distinguish enough angle marks on an encoder disk with a given small diameter and with the usual size of the teeth.

The invention is therefore based on the object of finding an arrangement according to the preamble of claim 1 in which, with a given size and number of code marks, significantly more angle marks than absolute marks can be identified.

In the solution to this problem according to the invention, characterized in claim 1, a code section of two or more code elements - number of elements E - is assigned to each angle mark to be identified, the code angles of which are equal to the sector angles of those E sector elements that precede the absolute mark in the direction of rotation, whereby also the Code angles of the code elements are arranged in the same order as the sector angles of the E sector elements. This makes it possible to use the angular and absolute pulses to differentiate the number of code pulses from the individual code elements. With a basic set T of different code elements, T ^E (E number of elements) minus 1 absolute marks can then be distinguished. Conversely, a required total number of marks M of absolute marks includes a basic set T of different code elements which is equal to the logarithm of the total number of marks M plus 1, the base of the logarithm being equal to the number of elements E belonging to each code section.

For example, if you choose two code elements (E = 2) per code section, you need a basic set T of four different code elements for a total number of marks M = 5. These can be code elements with 0, 1, 2, 3 or with 1, 2, 3, 4 etc. code marks.

In these cases, however, all permutations of the four different code elements must be used, including the combination of the two longest code elements. If one assumes in the simplest case that all code marks enclose the same basic angle a between them - equidistant arrangement - then the total length of the largest code section is equal to 2 x 5 a.

A more favorable use of the space on the encoder disk can be achieved according to a development of the invention with the same total number of brands M, if one starts from a total quantity A of basic sizes that is larger than the previously calculated basic quantity T. In this case, one can then to form the Select code sections from the total number of different possible combinations of code elements as short as possible combinations. In addition, the scope for designing the distribution of the angle marks over the circumference of the encoder disk increases considerably. Furthermore, the size of the blind spot per code section decreases with the number of angle marks.

In principle, the individual code marks can be arranged as desired in the code elements. However, preferably all code marks - code mark number Z - form a code track in which the code marks include the same basic angle a between them. In this case, the individual sector angles of the sector elements and the total angles of the code sections are also so large that they can be divided without remainder by this basic angle.

The main track with the angular and absolute marks and the code track with the code marks and the associated sensors can be arranged such that the angular pulses separating the code pulses of adjacent code elements lie between two code pulses. In a particularly simple embodiment of the invention, however, the arrangement is selected such that each angular pulse overlaps with a code pulse.

As in the prior art, the code track can preferably lie on a separate code disk which is coupled to the encoder disk turns synchronously with the encoder disc. However, the code track can also be arranged on the encoder disc itself next to the main track. Correspondingly, a code sensor for the code track with the sensor for the main track can also be accommodated in the same housing.

The sensors can work in a known manner optically, magnetically or inductively in connection with corresponding brands. Teeth on the circumference of a metallic disc, which are scanned with an inductive sensor, have proven particularly useful as code and / or angle marks.

A particularly advantageous embodiment of the invention results in connection with the Hartig pulse generator known from US Pat. No. 4,121,112: This works with a sensor disk which has teeth Z of equidistantly arranged from ordinary iron with relatively high eddy current losses on its circumference Z. Those teeth that are supposed to serve as an absolute brand - brand teeth - have much lower eddy current losses. In particular, they have a slot transverse to the direction of rotation, which is filled with a material of higher permeability. The associated sensor evaluate the ratio of the magnetic conductivity (permeability µ) to the electrical conductivity of each individual tooth. This ratio is significantly different for slotted and unslit teeth. As a result, the sensor delivers one pulse per tooth, but the angular pulse caused by a slotted tooth has a significantly larger amplitude; this function is independent of the speed.

In a four-stroke engine, such an encoder disk is preferably arranged on the camshaft rotating at half the speed of the crankshaft. However, it is also possible in this case to connect the encoder disc directly to the crankshaft and also to use an additional signal generator on the camshaft. The latter only needs to deliver an H signal during a first revolution and an L signal during the following one. With these signals, a clear distribution of the pulses from the encoder disk to the individual cylinders is then possible. In addition, the code pulses can be used to determine the respective speed.

According to a further variant of the invention, the main track with the angle marks and absolute marks can also be arranged on an encoder disk connected to the camshaft and the code track with the code marks can be arranged on a code disk connected to the crankshaft.

• Fig. 1 den grundsätzlichen Aufbau des Signalgebers,
• Fig. 2 die Verteilung der Winkel- und Codemarken auf die Zähne,
• Fig. 3 ein detailliertes Ausführungsbeispiel für den Decoder und
• Fig. 4 ein zugehöriges Impulsdiagramm zeigen.

The invention is explained in more detail using an exemplary embodiment, wherein

• 1 shows the basic structure of the signal generator,
• 2 shows the distribution of the angle and code marks on the teeth,
• Fig. 3 shows a detailed embodiment for the decoder and
• Fig. 4 show an associated timing diagram.

In Fig. 1, 1 denotes a sensor arrangement with a circular sensor disk 11 made of ordinary iron, which is rotatable about an axis 10 and which is coupled to the camshaft of an internal combustion engine. 54 teeth 12/13 are arranged equidistantly on the circumference of the encoder disk 11, of which individual teeth 12 have transverse slots 120 which are filled with a material of higher magnetic conductivity: these teeth also have the function of an absolute mark 121 and are referred to as mark teeth 12. The distance between adjacent teeth - from center to center - is determined by a basic angle α, which is 6 ° 40 'for 54 teeth.

Two successive absolute marks 121 delimit a sector element 122, 123 with the sector angle β1 or β2. Each sector element coincides with a code element of the same size (code angle = sector angle). Two successive code elements (number of elements E-2) each form a code section with a total angle y1 or y2: each absolute mark 121 therefore has a code section with the two preceding absolute marks and code elements. Each sector angle β, code angle and total angle y is divisible by the basic angle a without a remainder.

The distribution of the code sections over the circumference of the encoder disk 11 depends on the respective application and is explained schematically with reference to FIG. 2 for a six-cylinder engine: the numbers of all 54 teeth are listed there in the second line. In the third line below each tooth number, a 1 denotes a tooth with an absolute mark 121 - marker tooth 12 - and a 0 denotes a simple tooth code tooth 13 serving as a code mark. In the first line marked with P, the number of the assigned one is above the marker teeth 12 Absolute pulse (P1 to P15) specified.

In the fourth and fifth lines of FIG. 4, four code sections with two successive code elements each with an associated total angle y1 to y4 are specified. A total set A of five different code elements of 1, 2, 3, 4 or 5 code teeth (0; 00; 000; 0000; 00000) is provided.

The encoder disk 11 is assigned a pulse generator 14, which contains a sensor 141 and a discriminator 142. The sensor 141 scans the teeth of the encoder disk 11 and evaluates the different ratio of electrical to magnetic conductivity of the teeth 12, 13, as is described in more detail in US Pat. No. 4,121,112. The sensor delivers Sensor signal S - cf. the pulse diagram in Fig. 4 - in the form of a pulse per tooth, however, the angular pulse caused by a marker tooth 12 has a significantly larger amplitude than the code pulses caused by code teeth 13. The discriminator 142 distinguishes these amplitudes and supplies as encoder signal H a code pulse C at a first output per code tooth and an angular pulse W at a second output per marker tooth.

The encoder signal H is fed to a decoder 2, which consists of an element decoder 21 and a section decoder 22 and which supplies the absolute pulses at different decoder outputs P1 to P15 assigned to the individual absolute marks.

The basic function is explained on the basis of the worst case: This is the case if, at the start of the rotary movement of the encoder disk 11, the gap between the marker tooth with the number 12 in FIG. 2 and the following code tooth with the number 13, that is to say the beginning of the longest code element (6a) under sensor 141. As soon as tooth number 18 with the following absolute mark passes sensor 141, the angle pulse thereby triggered starts a counter in decoder 2 and determines the number of code pulses between this absolute mark and the following one, which is assigned to tooth 21. This value (2 - 3a) is saved by the following angular pulse. When the encoder disk is turned further, the following code pulses from the code teeth 22 to 25 are counted and the value (4 = 5a) is also stored by the angle pulse from the tooth 26. From these two stored values, the decoder then forms an absolute pulse at a decoder output P assigned solely to the marker tooth 26. Thus, in the worst case, the axis 10 must rotate through a blind spot of 93 ° and 20 '(∞ 14a) before the first absolute pulse is present. With this, a clear assignment of the first injection and / or ignition pulse to the correct cylinder of the internal combustion engine is then possible. Above all, sequential injection can be carried out - without injection into the exhaust stroke of a cylinder.

An embodiment of the decoder 2 with easily integrable components is shown in detail in FIG. 3, the discriminator 142 of the pulse generator 14 of FIG. 1 being shown again to facilitate the overview. This is followed by the element decoder 21, which essentially consists of a decoding counter 210 with five data outputs (corresponding to the maximum number of code teeth per code element). The counter is switched on by the negative edges of a counting signal C210 supplied via input C and supplies an element signal at the data outputs that represents the number of code marks per code element and that consists of an H signal at one of the data outputs and the rest of L signals consists. The counter receives an erase signal R210 via the input R. To form the count signal C210, the code pulses C and the angle pulses W are processed with the aid of two RS flip-flops 211, 212, the set and reset inputs of which are each connected upstream of an AND gate. Each flip-flop is implemented in a known manner with the help of two NOR gates.

Since in the present exemplary embodiment each code section consists of two code elements, the section decoder 22 has as many latch elements 221, 222, which are connected in series and connected to the counter 210 of the element decoder 21: With the positive edge of a clock signal Q211 present at a clock input L, this is done element signal applied to the data inputs and passed on to the outputs by the negative edge of the clock signal.

The outputs of the two latch elements are connected to one another in a matrix-like manner via AND gates G1 to G15, in such a way that at the end of each clock signal another AND gate supplies an absolute pulse which is thus uniquely assigned to an absolute mark 121.

The inputs and outputs of the flip-flops 211, 212 of the element decoder 21 are directly linked to one another and via the OR-elements 214, 215 and a NOR-element 216 to the counter 210 in the manner shown. The purpose of this combination is essentially to generate the clock signal Q211 with the occurrence of each angular pulse W and then an erase signal R210 for the counter 210.

When starting up, care must also be taken to ensure that only complete code elements are evaluated: For this purpose, the RS flip-flop 213, which supplies the delete signal R210 at its output 0 when the operating voltage U _B is applied, which is sent via the OR gate 215 at the reset input R of counter 210 lies. This signal remains until the flip-flop 213 is reset by the first angular pulse W, so that the code pulses fed to the counter 210 via the OR gate 214 are not taken into account. The counter 210 therefore only counts the negative edges of the code pulses C after the first angle pulse W. With the subsequent angle pulse - time t1 in FIG. 4 - the clock signal C1211 is then set, by means of which each latch element 221, 222 receives the respective element signal at its input takes over.

With the end of the angular pulse W at the time t2, the counter 210 is reset by the erase signal R210 which the NOR gate 216 supplies when neither the angular pulse W nor the signal C1210 is present.

The negative edge of the code pulse C coinciding with the angle pulse W must not be counted in this exemplary embodiment: this is achieved in that the clock signal 0211 - via OR gate 214 am Counter input C - is only cleared with the positive edge of the following code pulse C - time t4.

This state of the flip-flops then remains until t5, the time of the next angular pulse W. In the meantime, counter 210 is enabled and counts the negative edges - two - of count signal C210. At time t5, that output of the counter then has an H signal whose number corresponds to the number of code pulses in the preceding code element. A clock signal Q211 is generated again with the leading edge of the angular pulse, and the count of counter 210 from first latch element 221 and the count at the output of first latch element 221 are thus taken over by second latch element 222. With the trailing edge of the angular pulse, the counter 210 is then cleared again and detects the number of code pulses of the following code element.

The latch element 221 therefore always indicates at its output the number of code pulses of the first code element and the latch element 222 the number of code pulses of the second code element of each code section. The combination of these two numbers changes after each code element and is therefore an identity identifier for each code section and the absolute mark assigned to it; it is therefore evaluated via AND gates G1 to G15 to generate 15 different absolute pulses.

List of terms

• 1 encoder arrangement
• 10 axis
• 11 encoder disc
• 12 brand tooth
• 120 cross slot
• 121 absolute mark
• 122,123 sector element
• 13 code tooth / code mark
• 14 pulse generator
• 141 sensor
• 142 discriminator
• 2 decoders
• 21 element decoder
• 210 counters
• 211 RS flip-flop
• 212 RS flip-flop
• 213 RS flip-flop
• 214 OR gate
• 215 OR gate
• 216 NCR link
• 22 section decoder
• 221 latch element
• 222 latch element
• G1-G15 AND gate absolute pulse absolute mark code section code element
• C code pulse
• Z Code mark number Code sensor Code track Code angle Data input
• P decoder output
• E Number of elements signal
• H encoder signal
• A total
• y total angle
• T basic quantity
• a basic angle main sensor main track identity identifier
• R210 delete signal
• M total number of brands
• β sector angle
• S sensor signal
• L clock input
• Q211 clock signal
• W angular momentum
• C210 count signal

Claims (5)

1. An arrangement for identifying angle pulses comprising a pick-up arrangement (1) which includes a pick-up disc (11) and at least one code element,

- where the pick-up disc (11)

- is rotatable about an axis (10) and is coupled to the shaft of an internal combustion engine,

- bears a total number (M) of angle marks (121) which are distributed on a circle about the axis (10), form a main track, and enclose sector elements (122,123) each with a sector angle β),
where each code element

- is arranged in a circular code track about an axis which is coupled to the axis (10) of the pick-up disc (1),

- is rigidly assigned to an angle mark (121) which is to be identified, referred to as an absolute mark,

- extends at the maximum over a code angle which is equal to the sector angle (β) of the sector element which precedes this absolute mark (121) in the direction of rotation,

- contains a digital identity code in the form of no code mark (13) or at least one code mark (13),
with a pulse generator (14)

- which is arranged to be stationary in relation to the pick-up arrangement (1) and which scans the pick-up arrangement,

- which supplies a pick-up signal (H) with an angle pulse (W) for each angle mark (121) and with a code pulse (C) for each code mark (13),
and with a decoder (2) which includes a counter (210) for the code pulses (C) between in each case two angle pulses (W) and which at the end of each code element supplies an absolute pulse which identifies the absolute mark (121) at the end of the code element,
characterized in that all the angle marks are absolute marks (121), each of which is assigned an individual code section which comprises E code elements - number of elements E greater than 1 - with different combinations of identity codes and

that the code angles of the code elements of each code section are identical in respect of magnitude and sequence with the magnitude and sequence of the sector angles of those E sector elements which precede the absolute mark (121) in the direction of rotation.

2. An arrangement as claimed in claim 1, characterised in that a total quantity (A) of different code elements is provided which is equal to or greater than a basic quantity (T) which is determined by the logarithm of the total number of M of absolute marks plus 1 to a base which is equal to the number of elements (E) of the code elements assigned to each code section.

3. An arrangement as claimed in claim 2, characterized in that the pulse generator

has an individual code sensor for the code marks of the code track and

has a main sensor for the angle marks on the main track.

4. An arrangement as claimed in claim 2, characterised in that

the pick-up disc (11) of the pick-up arrangement (1) is provided on its periphery with equidistant teeth (12; 13) which are equal in width, consist of ferromagnetic material and serve as code marks,

individuals of these teeth - mark teeth (12) - serve as absolute marks (121) and for this purpose have lower eddy current losses than the remaining teeth, and

the signal generator (14)

- includes one single sensor (141) which analyses the ratio of the magnetic to the electrical conductivity of each tooth (12; 13) and supplies a pulse as sensor signal (S) in respect of each tooth, where the pulses produced by mark teeth (12) have a significantly greater amplitude than the pulses triggered by the other teeth (12),

- includes a discriminator (142) which separates the sensor signal (S) into angle pulses (W) and code pulses (Z).

5. An arrangement as claimed in claim 4, characterized in that

the decoder (2) includes an element decoder (21) and a section decoder (22),

the element decoder (21) includes a counter (210) for the code pulses (C) between two consecutive angle pulses (W)

the section decoder (22) includes latch elements (221, 222)

the number of which is equal to the number of elements (E) of the code sections,

the counter (210) of the element decoder (21) and the latch elements (221, 222) of the section decoder are connected in series in such manner that each angle pulse (W) triggers the forwarding

- of the count of the counter (210) of the element decoder (21) to the first latch element (221) and

- of the count of each latch element (221) of the section decoder (32) to the repsective following latch element (222) and

that the outputs of all the latch elements (221, 222) are logic-linked in the manner of a matrix via AND-gates (G1 to G15) to produce an absolute pulse assigned to each absolute mark (121).

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