FR2458812A1 - ENGINE TOWER COUNTER - Google Patents

Abstract

SYSTEM FOR MEASURING THE ROTATION SPEED OF A MOTOR INCLUDING A PART 62 WHICH MOVES AT A SPEED REPRESENTATIVE OF THE MOTOR SPEED, PART 62 INCLUDING AT LEAST ONE INDEX 63 AND THIS SYSTEM INCLUDING A DETECTOR 61 LIKELY TO BE MOUNTED ON THE MOTOR IN THE NEARBY OF THE MOBILE PART 62. ACCORDING TO THE INVENTION, THIS SYSTEM IS CHARACTERIZED IN THAT DETECTOR 61 INCLUDES TWO SENSITIVE ELEMENTS 71 AND 72 SPACES, DETECTOR 61 BEING SUITABLE TO BE MOUNTED SO THAT ITS TWO ELEMENTS 71 AND 72 ARE SPACED FROM ONE OF THE OTHER IN THE DIRECTION OF MOVEMENT OF THE INDEX 63 WHEN THE SAID PART MOVES EACH OF THE SAID ELEMENTS GENERATING A SIGNAL WHEN THE INDEX 63 PASSES IN FRONT OF IT, AND A CIRCUIT 22 CONNECTED TO THE SAID ELEMENTS 71 AND 72 AND RESPONDING TO THE INTERVAL OF TIME BETWEEN SAID SIGNALS. MEASURING INSTANT MOTOR SPEED.

Description

l Many systems are known for measuring rotational speed

  a moving part such as the crankshaft of an engine. For example, an ordinary tachometer gives an indication of the average rotational speed of the engine. However, in some cases it is necessary to have an indication of the instantaneous speed of the engine and the systems described in US Pat. No. 4,055,993 and British Patent 1,400,614 are provided for performing such a measurement. Briefly, a system described in these two patents comprises a magnetic sensor mounted in the vicinity of the teeth of the ring gear of the flywheel of an engine and each

  tooth passing in front of the sensor generates a pulse.

  A circuit connected to the sensor is responsive to the pulses and provides an indication of the time interval between successive teeth passing in front of the sensor, and this time interval is a function of the speed of the ring gear and the motor. Since there are many teeth on the crown each time interval provides a substantially instantaneous indication

  the speed of rotation of the engine.

  Such a system has proved in practice unsatisfactory,

  first because the crown is not a

  precisely and that the system requires

  substantially identical teeth in order to perform

  precise sures. The size and spacing of the teeth, or not, are not always constant and some

  areas of the crown are more prone to wear and

  than others. Indeed, sometimes a complete tooth may be missing. This results in an erroneous indication of

  engine speed, which in turn results in

  misstates in other controls based on the

  instantaneous rotation speed of the motor.

  The general object of the present invention is to provide a new and improved system for measuring the

  rotation speed of an engine, which eliminates the

mentioned above.

  The device for measuring the speed of rotation according to

  the invention comprises a sensor consisting of two ele-

  spaced detector elements. The sensor is mounted in the

  swimming around the periphery of the rotating part of an engine

  and said elements are spread towards the movement

  marked index on said rotating part. The two elements are used to determine the time interval required for the index to move from one element to the other, and this time interval is a function of the rotational speed of the index and therefore the rotating part that carries it. Both elements detect the same index by measuring the time interval. The rotating part can have a large number

  separate index and the detector can detect

  its successive points and therefore be used to determine the instantaneous speed of rotation of the

  rotating part on a total or partial cycle.

  The figures of the appended drawing will make it clear

  how the invention can be realized.

  Figure 1 shows an engine equipped with a compliant

me to the present invention.

  Figure 2 is a block diagram of the system according to

the invention, more detailed.

  FIG. 3 is a timing diagram of signals, illus-

  the operation of the system according to the invention.

  Figures 4A and 4B are block diagrams of the

  operation of the system according to the invention.

  In Figure 1, there is shown a motor 10 which may be a conventional internal combustion engine, for example six-cylinder in-line, NH diesel type manufactured by the applicant. Such an engine comprises a cylinder head 11, an engine block 12, an oil sump 13 and a rocker housing 14 fixed to the upper part of the cylinder head 11. The pistons (not shown) of the engine are driven by a movement of back and forth inside the cylinders (also not shown) and are connected to drive a crankshaft 66 in rotation. A flywheel is mounted on this crankshaft and comprises a ring gear 62, the teeth 63 of which can selectively be engaged by the starter (not shown) in order to

start the engine.

  A plurality of fuel injectors 16 inject measured amounts of liquid into the cylinders after the air admitted into the cylinders has been sufficiently compressed to cause combustion of the resulting mixture. Injectors 16 may be of the type described in US Pat. No. 3,351,288.

  caOnone 17 fuel supply connects the injectors

  16 to the fuel system

  as a pump 18 for example of the type described in the

  U.S. Patent 3,139,875. Pump 18 draws fuel from

  in a reservoir 21 and forms a regular source

  A throttle valve 1 & a is incorporated in the pump 18 and allows the operator operating the engine to regulate the fuel pressure delivered to the injectors. A return line 24 is also connected to each of the injectors 16,

  1 This line reducing the fuel from the injectors 16 to the fuel

see 21.

  The engine 10 has a lubrication system for circulating a lubricant such as oil through the various moving parts of the engine. The lubrication system comprises a pump 41 which draws lubricant contained in a tank of the housing 13 and circulates it under pressure through a passage 42 of the engine block. The pressure in the passage 42 is regulated

  by a regulating valve 43, mounted in a drift line

  44, which is connected in parallel to the

pump 41.

  A plurality of mechanical couplings, illustrated by the

  dashed lines in Figure 1 and referencing

  67 and 69, connect the crankshaft 66 to the pump

  18 and the lubricant pump 41,

  tively. A system according to the present invention is provided and it comprises a detector 51 which is preferably mounted

  in the rocker housing14 and is sensitive to

  a moving part of the engine. For example, the sensor 51 may be of the magnetic coil proximity sensor type which is mounted in the vicinity of the rocker arm which actuates the injector 16 of the cylinder

  number 1; This rocker arm pivots during the injection

  which occurs towards the end of the piston stroke of the piston number 1 cylinder and this movement allows the detector 51 to generate a signal corresponding to the end of the compression stroke of the piston of the number 1 cylinder. signal

  is used as one of the engine parameters.

24588 12

  The system further includes a plurality of detectors including a fuel pressure sensor 27 connected to line 17, a lubricant pressure sensor 46 connected to the passage 42 and an air pressure sensor 34 connected to the collector. admission. The detector 51 is connected to a time counting module 22 and the detectors 27, 34 and 46 are connected to an AC-DC converter 23, the components 22 and 23 being connected to the processor 29. The processor 29 has outputs in the direction reading device 70 which can provide, for example, visual indications and

permanent records.

  The engine further comprises a system for measuring the

  speed of rotation of the engine according to the present invention.

  tion, which is particularly useful in combination with

  the engine test systems that use the detec-

  27, 34 and 46. This system measures the rotational speed of a moving part of the engine, this part carrying at least one and preferably a series of identifiable indexes. In the example shown, this part

  mobile is the ring gear of the engine flywheel 10.

  As is known, the ring gear 62 is relatively

  large and has a plurality of teeth 63 to

  its periphery, the teeth forming the series of indexes.

  As will be seen later, the system of measurement of the speed of rotation comprises a detector 61 which responds to the movement of the teeth 63 which pass in front of

  he and the detector 61 generates signals which appear

  on a line connecting the detector 61 to the module

  time counting 22 and the processor 29.

  As shown in Figure 2, according to the present invention

  detector 61 comprises two spaced apart sensitive elements which in the present example are poles or

2 458812

  1-magnetic cores 71 and 72 on which are wound coils 73 and 74. The coils 73 and 74 are mounted between conductors 76 and 77 and a ground connection or ground 78. The detector 61 is mounted so that the one of the ends of each of the elements 71 and 72

  positioned in the vicinity of the outer periphery

  The ring 62 is made of a magnetic material such as steel and when one of the teeth 63 passes one of these elements, it modifies the magnetic field through the coil.

  of this element which generates an electrical impulse.

  As shown in FIG. 2, the detector 61 is mounted so that the two elements 71 and 72 are spaced in the direction of the movement of the tooth 63 when the ring gear 62 rotates, and consequently when each tooth 63 passes in front of the detector 61, this generates an electrical pulse or a signal first in the coil 73 and then dahs the coil 74, assuming that the ring 62 rotates in the direction of

  clockwise when looking at Figure 2.

  The two conductors 76 and 77 are respectively connected to the inputs of two shaping circuits 81 and 82 which

  convert pulses into slots. Looking back

  3, the signals A and B represent the outputs of the coils 73 and 74, respectively, and the

  signals C and D represent the outputs of the two circuits

  Thus, the circuits A, B, C and D of FIG. 3 represent the voltage variations with respect to the time at the inputs and the outputs of the circuits 81 and 82 when the ring gear 62 turns in the direction of rotation. clockwise. As can be seen in FIG. 3, the signal generated in the coil 74 is out of phase with the signal generated in the coil 73. This phase shift 1 is indicated by the symbol At on the Figure 3 and is equal to. the time difference between the rising edges 83 and 84 of the signals at the outputs of the circuits 81 and 82, respectively, when a single tooth 63 first passes the element 71 and then in front of the element 72. The measurement system of the rotational speed further comprises a clock oscillator 86 which generates a signal

  of fixed frequency designated by the signal E in FIG.

  It will be noted that the frequency of the oscillator 86 is much greater than that of the pulses of the signals A, B, C and D. The signal coming from the oscillator 86 is transmitted to the input of a register-counter 87 which operates under the control of a time control circuit 88. The circuit 88 has two inputs 91 and 92 connected to the outputs of the shaping circuits 81 and 82 and the control circuit 88 generates turn-on and turn-on signals. stopping on the outputs 93 and 94 which are connected to the counter 87. When an "on" signal appears on the output 93, the counter 87 receives and counts the pulses of the oscillator 86 and when a "stop" signal appears on exit 94, the counter 87

  stops counting the pulses of oscillator 86.

  The circuit 88 generates a signal "on" on the line 93

  in phase with the rising edge 83 of signal C and

  dre a stop signal at the output 94 in phase with the falling edge 84 of the signal B. As illustrated by the signal F, we see that the counter 87 receives and

  account of the portions of cycles or groups of pulses

  oscillator 86, each of these groups of pulses being indicated by the reference 96 on the signal F. Since the duration of a group 96 is equal to the interval of time At, it is seen that the counting of the counter 87 is a direct function of the duration of the time interval Δt and of

  the frequency of the oscillator 86 (which is known).

  The count of the counter 87 is transmitted to the processor 29 at the end of this count by an edge 84 and the counter 87 is reset after each reading. As will be described with reference to the diagram of FIG. 4, the processor 29 calculates the speed of rotation Vr of the crankshaft in revolutions per minute and also generates a signal representative of the time interval Δt, and

  these parameters are used in the various

  such as fuel and lubricant systems

  the power balance of the cylinders and the performance of the turbocharger. The processor 29 can calculate the speed of the machine according to two methods (1) using the indications of the counter 87, the radius R separating the center of the ring 62 and the elements 71 and 72 and the space X between the two elements 71 and 72, the parameters X and R being known and entered into the processor by the system operator, or (2) using the time slot count and a factor that is automatically calculated by the processor 29 based on the counting time interval and

signals received from the detector 51.

  As mentioned above, the detector 51 is responsive to a rotating part of the cyclically moving motor such as a rocker arm for the injector of one of the cylinders. The rocker arm moves to inject fuel once each cycle of the engine, for a four-stroke engine, i.e.

  twice for two revolutions of the crown 62.

  As shown in Figure 2, another counter 98 is

  in module 22, and this counter 98 also counts

  the cycles of the clock oscillator. In the present example, the output of the oscillator-86 is connected to a divider 99 and then to the counter 98. The signals from the detector 51 are transmitted to a shaping circuit 101 and a control circuit 102 and controls the start and stop of the counter 98. Read and reset lines connect the counter 98 to the processor 29. A pulse from the detector 51 causes the counter 98 to read by the processor 29, which immediately resets the counter 98. Thus, the counting of the counter 98 represents the time interval between the signals of the detector 51 which concerns the speed of rotation of the motor. This count is also, of course, a function of the frequency of the oscillator 86 and

  of the divisor factor 99, which are well known.

  As shown in FIG. 4A, at the beginning of step 106, a plurality of parameters are defined. The parameters are described below. During step 107 the system questions whether the engine is running and this can be determined by whether readings are read at the output of the counter 87. If the engine does not work, step 108 causes the engine to operate. operator to start the engine and to

operate empty.

  A hand-held device or operator interface (not shown) that forms part of the reader system 70 may be provided to indicate the incentives and other data and to receive operator instructions, the hand-held device being of a known type. If the engine runs idle, the process proceeds to step 109 where it is determined whether the CALFLAG has been established. CALFLAG is established when a conversion factor (CNVNFAC) is available in the system, this factor being a constant used in the calculation of the instantaneous engine rotation speed, such as

it will be described below.

24.58812

  1 The constant CNVNFAC can be determined automatically

  by the system or from information provided

  to the system by the operator.

  Assuming first the situation where CALFLAG has been established, the process proceeds to step 111 where a PPCNTR read series are taken from counter 87 which measures the interval A t for the passage of a tooth 63 from a element 73 to another element 74. During step 111, output signals representing A t are also generated, these signals preferably being in binary form that can be used by processor 29. The counting of A t then goes to step Where the instantaneous speed of the engine is calculated by dividing the factor CNVNFAC by A t read in the register 37. The notation PP COUNT indicates that this reading is derived from the pole-pole count. The value of the rotational speed is displayed during step 113, for example on a single visual screen of the device

held by hand.

  If the CALFLAG has not been established indicating that the CNVNFAC is not in the system, the process proceeds to step 116 where the operator is prompted to enter either the X and R dimensions (see Figure 2), either NULL The system reads the response from the operator during step 117 and at step 118 the system queries whether the operator response was NULL. If the decision is NOthe system proceeds to manual calibration step 119 o CNVNFAC is calculated from the X and R values entered by the operator at step 116. CNTRFRQ is the frequency of oscillator 87. The system establishes then CALFLG in step 120 and returns to step 109, and the rotational speed is calculated in steps 111,

112, and 113.

  1 If the operator response is NUL, the process proceeds from step 118 to an automatic calibration routine, starting at step 122, where CEMCTR starts. It's the

  counter 98 (FIG. 2) which counts the pulses

  divider 99 that appear during the

  51. The counter 98 also includes

  a register for these signals which records a count, while the next count is done and when a count is recorded, the register generates a ready signal which appears at the instant of reception of a signal from the detector 51. This signal ready is detected in steps 123 and 124 and a calibration routine is performed during step 124 by emptying said register and making an index I equal to zero. At the stage

  126, the counter PPCNTR 87 is started to perform

  to kill successive successive readings of the oscillator cycles during A t. During the steps 127 to 130, a series of counts A t are read and the number I of reading is counted between two successive signals of the detector 51, the counts A t being stored in a TIMINT memory. The readings begin at a signal from the detector 51 and the system is looped through steps 127 through 130 until the second signal from the detector 51 is received, indicating that the crankshaft has made two revolutions or a

complete engine cycle.

  In step 132, the CEMCNTS from register 98

  is read, which indicates the time of a motor cycle.

  In step 133, the average value AT (AVGCTS) for

  the engine cycle is calculated by totaling the

  their A t and dividing by the number I of reading between two signals of the detector 51. During the step 134 the factor CNVNFAC is calculated by the equations 1 indicated. The pulse frequency from divider 99 is CNTRFRQ2. At the next step 135, the CALFLG is

  established and the system proceeds to step 109.

  The module 22 and the processor 29 may be com-

  usual posers. The processor 29 is programmed according to standard programming techniques from the

  diagrams and description indicated.

  The system has been described according to a variant of

  the two elements 71 and 72 are spaced a distance less than the distance between two successive teeth 63 of the ring 62. Elements are preferably placed very close to obtain a closer instantaneous speed. The elements 71 and 72 could, however, have a spacing greater than the pitch of the teeth 63, and in this case one could use several counters and multi-vibrators, so that the counters are started and stopped by the first and the second of the signals from a

  particular tooth. In the different forms of

  vention, the time required for each tooth to move from one element to another is detected and measured to derive the instantaneous speed of rotation of the engine. While magnetic proximity sensors have been described, it is obvious that other types of detectors could be used, for example photocells could be used. The detector could be used with a motor part other than the starter ring and it would only be necessary to provide at least one index on this part. In addition, one could fix a part on the engine such as a disc having a series of holes

or brands.

1 3

  1 It will be clear from the previous description

  that a new and effective system for measuring the instantaneous speed of an engine has been created. Since each of the elements 71 and 72 of the detector 61 generates a signal in response to the passage of a single index, the measurements are relatively insensitive to the variations between the successive points. Moreover, even if

  index of a series of points was missing, the system provided

  a precise measure of the instantaneous speed of the

engine.

  In this description and / or drawings, the

  abbreviations EMC, CALFLAG and CEMCNTS have the following meanings EMC means the event marking signal

  Cycle emitted by the detector 51.

  - CEMCNTS is an abbreviation for

  counting of the EMC signal, carried out by the counter 98.

  - CALFLAG refers to the calibration of the identification indicator

the microprocessor.

-14-

Claims (7)

R E V E N D I C A T IO N S   A system for measuring the rotational speed of an engine (10) comprising a portion (62) traveling at a speed representative of the engine speed, the portion (62) having at least one index (63) and said system comprising a detector (61) capable of being mounted on the motor in the vicinity of the movable portion (62), characterized in that said detector (61) comprises two spaced sensitive elements (71) and (72), said detector 61) being adapted to be mounted so that its two elements (71) and (72)   spaced apart from each other in the direction of movement   the index finger (63) when said part moves, each of said elements generating a signal when the index (63) passes in front of it, and a circuit (22) connected   (71) and (72) and is sensitive to   time interval between said signals.   2. System according to claim 1, characterized in that each of said elements comprises a detector magnetic proximity.   3.- System according to claim 1, characterized in that said circuit comprises an oscillator (86), a computer (87) connected to said oscillator to count oscillator cycles, and counting means and control (88) sensitive to said signals and controlling the operation of said counter, said control means (88) starting a count cycle in response to a signal from one of said elements (71), (72) and stopping the counting cycle in response to the signal from the other of said elements (71), (72), said index (63) passing first in front of the first of said elements and then in front of the second.   4. A system according to claim 1, characterized in that said movable portion (62) is integral in rotation with the engine flywheel and has a plurality of spaced indexes (63). 5.- System according to claim 1, characterized in that said portion (62) is the ring cooperating with the starter and in that said index (63) are the teeth of the crown.   6. System according to claim 3, characterized in that the number counted in said counting means (87) is a function of said time interval and   in that there is further provided a processor (29) sensi-   audited number counted for speed calculation of the motor.   7. System according to claim 6, characterized in that said portion (62) rotates about an axis and in that said elements (71) and (72) are spaced apart by a distance R from said axis and are spaced at a distance X from each other and in that said processor (29) calculates the motor speed from said count and dimensions R and X. 8.The system of claim 7, wherein said portion (62) rotates with the motor, characterized in that said system further comprises sensor means (51) responsive to a cyclically moving part of the motor for generating EMC signals and in that the processor (29) ) calculates engine speed from said count and average engine speed between two successive EMC signals.   9. A method for obtaining an indication of the rotational speed of an engine comprising a movable part (62) provided with at least one index (63), characterized in that the moment or the index (63) passes a first element (71), in that it is detected when the index (63) passes a second element (72) which is spaced from said first element (71) and in that an indication is given of the time interval for said index to move from the first element to the second.   10. A process according to claim 9, characterized in that the engine speed is calculated from said time interval.