JP3490541B2 - Engine speed detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting an engine speed based on a pulse generated every predetermined crank angle in synchronization with the rotation of a crankshaft, and more particularly to a device for detecting four engine operation strokes (intake → compression). → Combustion → Exhaust) 1 of
An engine speed detecting device capable of calculating a stable engine speed by averaging the sparse / dense states of the number of pulses generated during one stroke by performing the cycle calculation limited to the number of pulses corresponding to the stroke. It is about.

[0002]

2. Description of the Related Art Generally, in an engine control device,
In order to grasp the operating condition and determine the control parameters,
The engine speed is constantly detected. For this reason, conventionally, for example, there has been proposed an engine speed detecting device which is provided with a sensor means related to a crankshaft and counts pulses from the sensor means to calculate an engine speed.

However, it is known that the count value of pulses generated in synchronization with the rotation of the crankshaft (corresponding to the engine speed) fluctuates with time according to the operation stroke of each engine cylinder. . This is because, when paying attention to one cylinder, the number of pulses within a certain period becomes maximum in the combustion stroke, and thereafter decreases in the order of exhaust stroke, intake stroke, compression stroke, and becomes minimum in the compression stroke.

FIG. 8 shows the number N of pulses counted within a fixed period.
It is a characteristic view which shows the time change of p (rotation speed information). Here, two strokes are performed for one rotation of the crankshaft.
The case of a cylinder diesel engine is shown.
The engine operation stroke is one cycle in four strokes, and the crankshaft makes two revolutions in one cycle.

In the case of a 4-cylinder engine, each cylinder is
Combustion stroke in the order of # 1 cylinder, # 3 cylinder, # 4 cylinder, # 2 cylinder (remaining cylinders are the other strokes out of 4 strokes)
Therefore, the pulse number Np shows a peak value for each stroke (one stroke corresponding to 1/2 reciprocation of each cylinder), and the pulse number Np shows a minimum value during the shift to the next stroke. Therefore, as shown in FIG. 8, the pulse number Np periodically fluctuates in accordance with the engine speed, and one stroke (crankshaft 1/2
During rotation, one peak value will be shown.

FIG. 9 is a block diagram schematically showing a conventional engine speed detecting device using a pulse number Np within a fixed period. In the figure, 1 is directly connected to an engine (not shown) and is rotationally driven. The crankshaft 1a is a projection made of a magnetic material, which is provided along the outer circumference of the crankshaft 1 at equal intervals (at predetermined crank angles). Reference numeral 2 denotes a sensor formed of an electromagnetic pickup or the like which is arranged so as to face the protrusion 1a.
A pulse P is output every time a is opposed to.

Reference numeral 30 denotes an ECU (electronic control unit) composed of a microcomputer for obtaining the engine speed Re based on the pulse P, and pulse counting means 301 for counting the number Np of the pulses P input within a fixed period, The engine speed calculation means 302 calculates the engine speed Re based on the pulse speed Np.

FIG. 10 is an explanatory view showing the operation of the pulse counting means 301 in FIG. 9, and FIG. 10 (a) shows the engine speed Re.
Is large (the number Np of generated pulses P is large),
(B) shows the case where the engine speed Re is small (the number Pp of generated pulses P is small).

In FIG. 10, T is a fixed period for counting the pulse number Np, and desired data (pulse number Np
The time is set in advance so that p) can be obtained. tc is a timing (minute time) for calculating the engine speed Re, and at each calculation timing tc, the engine speed Re is calculated based on the data (pulse number Np) counted within the immediately preceding constant period T. It

As is apparent from FIG. 10, the number of pulses Np (the frequency of occurrence of the pulse P) counted within the fixed period T is
When the engine speed Re is large (a), it is large, and when the engine speed Re is small (b), it is small.
Further, as shown in FIG. 10 (b), at low rotation speed, the rotation speed fluctuation during the engine operation stroke becomes large, and the pulse P
Occurrence frequency fluctuates during one stroke (see FIG. 8).

In particular, when the engine speed is low, the number of pulses Np counted within a certain period T is significantly reduced, and it may be less than one stroke (1/2 rotation of the crankshaft 1). Therefore, the count value of the pulse number Np increases / decreases depending on the count timing (constant period T). For example, as shown in FIG. 8, the count value becomes maximum during combustion control during each stroke, and becomes minimum during transition during each stroke. .

As described above, in the conventional device, the engine speed Re is calculated based on the count value of the pulse number Np. However, the pulse number Np changes at each calculation timing tc (operating stroke), and the counting is performed. Since the corresponding stroke of the target pulse P is unknown, the accurate engine speed Re
Can't ask. Especially at low speeds,
Since the fluctuation of the engine speed Re is large, a large error occurs in the calculated value of the engine speed Re.

[0013]

As described above, the conventional engine speed detecting device calculates the engine speed Re on the basis of the pulse number Np counted within the fixed period T. Since the engine speed (pulse number Np) during the operation stroke fluctuates, the number of pulses N is affected by the density of the pulses P during one stroke.
There is a problem in that the count value of p fluctuates, and eventually an error occurs in the calculated value of the engine speed Re.
Further, if the fluctuation of the pulse number Np is to be suppressed, a processing device for that purpose is further required, which causes a problem of cost increase.

The present invention has been made in order to solve the above problems, and the frequency of pulses during a stroke is generated by performing the periodic calculation by limiting the fixed number of pulses corresponding to one stroke. It is an object of the present invention to obtain an engine speed detecting device capable of averaging sparseness and denseness of the engine and calculating a stable speed.

[0015]

An engine speed detecting device according to claim 1 of the present invention is provided in association with a crankshaft of an engine, and has a frequency proportional to the engine speed in synchronization with the rotation of the crankshaft. Is provided for each predetermined crank angle, and an ECU that calculates the engine speed based on the pulse output from the sensor means. The ECU calculates the time difference of each pulse. Means, a sum total calculation means for summing a fixed number of time differences corresponding to one stroke of the engine operation stroke, and a rotation speed calculation means for calculating an engine speed based on the summed time difference calculation value. And the engine times based on the pulse
Judgment means for judging the low rotation number of rotations, and the judgment result
Data that fixes the engine speed data in response to the result
Including the fixing means, the rotation speed calculating means responds to the determination result.
Then, the calculation function is prohibited .

[0016]

[0017]

[0018]

According to a second aspect of the present invention, there is provided the engine speed detecting device according to the first aspect, wherein the determining means determines not only the low engine speed state but also the engine speed zero state. Has a threshold value, and the data fixing means is
In response to the determination result, the engine speed is switched to the low speed or 0 speed state.

[0020]

According to the first aspect of the present invention, a certain number of pulse detection periods corresponding to one stroke (1/2 rotation of the crankshaft) are calculated, and the frequency of pulse generation during the engine operation stroke is varied (rotation). A stable engine speed is obtained by averaging and suppressing the influence of (variation). Also, the time
If the difference data indicates a low rotation abnormal value, change the engine speed.
Unconditionally prevent wasted time as fixed data.

[0021]

[0022]

[0023]

Further, according to the second aspect of the present invention, the fixed data has a threshold value for determining an abnormal low rotation speed and the fixed data is switched to the low rotation speed state or the rotation speed 0 state to improve the reliability of the fixed data. .

[0025]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a functional block diagram showing a first embodiment of the present invention, 3 corresponds to an ECU 30, 1, 1a,
2, P and Re are the same as described above. In this case, the ECU 3 is composed of the following elements 31 to 39.

Reference numeral 31 is a time difference calculating means for calculating the time required between the pulses each time the pulse P is input, that is, the time difference Δt (i), and 32 is the latest data of the time difference Δt (i) which is always a fixed number. Secure a certain number of bytes secured as a column RA
M and 33 are pointers for sequentially moving addresses in the securing RAM 32 to secure a fixed number of time differences Δt (i).

Reference numeral 34 is a total sum calculating means for summing a fixed number of time differences Δt (i) corresponding to one stroke of the engine operation stroke, and 35 is a number counter for counting the total number of data operations in the total sum calculating means 34. , 36 is the time difference Δt
The engine speed Re based on the sum calculated value Ti of (i)
This is a rotation speed calculation means for calculating 1.

Reference numeral 37 is a judgment counter (judging means) for judging the low engine speed of the engine speed based on the pulse P, and 38 is data of the engine speed in Re2 in response to the judgment result D of the judgment counter 37. Data fixing means 39 for fixing is a data outputting means for outputting the calculated engine speed Re1 or the fixed engine speed Re2 as the final engine speed Re.

The rotation speed calculation means 36 has its calculation function prohibited in response to the determination result D indicating the low rotation state. Therefore, the data output means 39 normally outputs the calculated engine speed Re1 and outputs the fixed engine speed Re2 when the low rotation state is determined.

The judging means 37 has a judging threshold value (described later) for judging not only the low engine speed but also the engine speed of 0, and the data fixing means 38.
In response to the determination result D, the engine speed Re2 is switched to the low speed or 0 speed state.

2 to 5 are flowcharts showing the operation of the ECU 3 in FIG. 1, and FIG. 2 is a time difference calculating means 31 to 31.
Pulse P detection processing by the pointer 33, FIG. 3 is a calculation processing operation of secured data by the sum calculation means 34 and the number counter 35, FIG. 4 is a calculation processing operation of the engine speed Re1 by the rotation speed calculation means 36, and FIG. The determination processing operation of the low rotation state by the determination counter 37 and the data fixing means 38 is shown respectively.

FIG. 6 is an explanatory diagram schematically showing the operation of the time difference calculation means 31 to the number counter 35. FIG. 6A shows the case where the engine speed Re is large (the number Pp of generated pulses Np is large). b) shows the case where the engine speed Re is small (the number Pp of generated pulses P is small).

In FIG. 6, tc is the calculation timing similar to that described above, Ti11 and Ti12 are sum calculation values (a pulse cycle of a fixed number) when the engine speed Re is large, and Ti21 and Ti22 are engine speed R.
It is the sum operation value when e is small. Also here
Assuming that the crankshaft 1 is provided with 18 protrusions 1a, the fixed number (the number of protrusions 1a corresponding to 1/2 rotation of the crankshaft 1) is set to 9.

FIG. 7 is an explanatory diagram showing the memory space in the secure RAM 32 in association with the pointer 33, and Z is a pulse for one rotation of the crankshaft 1 corresponding to the number of protrusions 1a provided on the crankshaft 1. Number, Z / 2 is the pulse P for one stroke
, T (i-3), ..., T (i) are the detection times of each pulse P. At the time of detecting each pulse P, the pointer 33 stores the elapsed time from the previous detection time t (i-1) as the time difference Δt (i) in the memory space corresponding to the current address in the secured RAM 32, and It is designed to move to an address.

Next, the operation of the first embodiment of the present invention shown in FIG. 1 will be described with reference to FIGS. 6 and 7. First, the time difference calculation means 31 in the ECU 3 determines the time t
When the pulse P from the sensor 2 is detected in (i), the time required from the detection time t (i-1) of the immediately preceding pulse P is measured as the time difference Δt (i). At this time,
The time difference Δt (i) is represented by the following equation (1).

[0036] Δt (i) = t (i) -t (i-1) (1)

The measured amount of the time difference Δt (i) calculated by the equation (1) is sequentially stored in the address space in the secure RAM 32 designated by the pointer 33. Actually, as will be described later, the previous and current pulse detection times are the time RAM.
Time difference Δt (i) after being taken into (not shown)
Is calculated. Subsequently, the total sum calculation unit 34 calculates the required time between each pulse for one stroke, that is, the total sum calculation value Ti of the time difference Δt (i) by the sum of the data in the secured RAM 32 as shown in the following formula (2). Ask for.

Ti = Σ {Δt (k)} (2)

However, in the equation (2), the time difference Δt
(K) is a range of k = i−Z / 2 + 1, ..., I−1, i, where Z / 2 (constant number) of data are summed up.
The time difference Δt between the pulses is calculated by the time difference calculation means 31.
The processing operation of calculating (i) and storing it in the secured RAM 32 is
The calculation is performed every time the pulse P is generated, but the sum calculation means 3
The processing operation of 4 is performed at regular operation intervals. As a result, the total sum calculated value Ti always indicates a fixed number of pulse cycles corresponding to one stroke, and the density of the occurrence frequency of the pulse P that varies within one stroke is averaged, and the influence of the variation is suppressed. It

That is, when the engine speed Re is large, a small sum operation value Ti11 is obtained as shown in FIG. 6 (a).
And Ti12, and when the engine speed Re is small, a large sum calculation value Ti21 as shown in FIG.
And Ti22, and a stable value is calculated in any case. In particular, as shown in FIG. 6B, even when the engine speed Re is small and the frequency of occurrence of the pulse P is unstable,
Stable sum calculation values Ti21 and Ti regardless of fluctuations
22 is obtained.

Further, at this time, since the processing by the sum calculation means 34 is performed at a constant cycle as shown by the calculation timing tc, as shown in FIG. There is a possibility that Ti21 and the previous sum calculation value Ti22 overlap and meet. However, FIG.
As described above, since a fixed number of pieces of data are always stored in the secure RAM 32, there is no hindrance to the summing operation processing operation.

As described above, by averaging the pulse P for one stroke of the engine operation stroke (1/2 rotation of the crankshaft 1), it is possible to suppress the influence of the rotation fluctuation in the operation stroke. . In addition, since only a fixed number of data summing calculation processes are performed and it is not necessary to perform the filter processing calculation, the calculation accuracy can be improved.

Also, the time required for inputting each pulse P is secured R
When the data is stored in the AM 32, the pointer 33 is moved to always reserve a certain number of latest data strings, so that it is not necessary to move the data in the secured RAM 32, and the data movement processing time is shortened. be able to. In addition, in order to prevent the occurrence of a calculation abnormality, for example, secure R
During the summation processing of the data in the AM 32, the interrupt processing for detecting the pulse P is prohibited.

On the other hand, the judgment counter 37 refers to the generation interval of each pulse P, and outputs a judgment result D when the data abnormality (overflow state) in the securing RAM 32 is indicated, and the data fixing means 38 is used. , The engine speed is unconditionally fixed data Re2. That is, when the engine speed extremely decreases, the fixed data Re2 is positively set without calculating the abnormal speed.

Further, the judgment counter 37 has a judgment threshold value for detecting the generation interval of the pulse P, and depending on whether or not the judgment threshold value is exceeded, the fixed data is kept in the low rotation speed state and no rotation speed ( 0 rpm) state.

The specific control processing operation of the first embodiment of the present invention will be described below with reference to FIGS. First, the time difference calculation means 31 in the ECU 3 responds to the pulse P from the sensor 2 related to the crankshaft 1,
The interrupt processing routine (FIG. 2) at the time of pulse detection is executed.

That is, in step S210, prior to calculating the time difference Δt (i) between each pulse,
The previous pulse detection time t (i-
1) and the current pulse detection time t (i) are loaded into the time RAM in the time difference calculation means 31.

Further, in step S212, the secured R
A pointer 33 for moving an address to the AM 32 (see FIG. 7).
(Refer) by counting (incrementing)
Processing is performed to indicate the address in the secure RAM 32 that is shifted down by one. As a result, step S218 described below is performed.
Time difference Δt (i) (= t (i) −t
The data value of (i-1)) has a fixed number of bytes of secured RAM.
The pointer 33 is ready to be stored in the memory space of the address for the latest pulse indicated by the pointer 33.

As described above, the address position indicated by the pointer 33 is sequentially shifted downward to the address in the securing RAM 32 for the next pulse every time the pulse P is detected, and is changed to the lowest point of the securing RAM 32. When it reaches, it is set to return to the highest point and always cyclically instruct the memory space in the secure RAM 32.

Therefore, the moving step S of the pointer 33 is performed.
Subsequent to 212, in step S214, the count value of the pointer 33 (depending on the number of data at the pulse detection time) is the predetermined number of data in the secure RAM 32 (that is,
It is determined whether Z / 2) in FIG. 7 has been reached. If the determination result is NO and the count value is less than or equal to the number of bytes of the secure RAM 32 (that is, the lowest point Z / of the secure RAM 32).
2 or above), the process directly proceeds to step S218.

On the other hand, the determination result of step S214 is YE.
S, the count value of the pointer 33 is secured in the RAM 3
If it is below the lowest point Z / 2 of 2 (larger value),
In step S216, the pointer counter in the pointer 33 is cleared. As a result, the address position indicated by the pointer 33 next time is set as the highest point of the secure RAM 32,
In addition, after clearing a calculation prohibition flag (described later) in the minority pulse (low rotation) processing, the process proceeds to step S218. Through the above steps S210 to S216, the memory space for ensuring the data of the following time difference Δt (i) is surely allocated.

Subsequently, in step S218, from the current pulse detection time t (i) to the previous pulse detection time t.
(I-1) is subtracted, and this is taken as the required time between pulses, that is, the time difference Δt (i), and the above processing step S212.
The calculation result is stored in the address of the securement RAM 32 indicated by the pointer 33 counted by.

At this time, since the movable pointer 33 indicates an address for securing the time difference Δt (i) regarding the latest pulse every time the pulse P is detected, the latest data is always stored in the securing RAM 32 without fail. To be done. Also, secure R
The AM 32 always secures a time difference Δt (i) between the latest pulses of a fixed number of pulses (Z / 2 corresponding to one stroke).

Then, in step S220, in order to enable the time difference calculation at the next pulse detection,
The current pulse detection time t (i) is secured in the time RAM as the previous pulse detection time t (i-1). Further, in step S222, the time difference Δt (i) between the pulses is
Has been normally secured, a counter (described later) for determining a small number of pulses (low rotation) is cleared.

The time difference data calculation routine consisting of the above steps S210 to S222 is repeatedly executed by the interrupt processing of the time difference calculation means 31 each time the pulse P is detected, and the latest time difference data string is always secured in the RAM3.
Store in 2.

Next, an arithmetic processing routine (FIG. 3) of a constant cycle by the sum total operation means 34 will be described. First, when the interrupt process for pulse detection (FIG. 2) is performed during the total sum calculation process and the time difference data in the secure RAM 32 is updated, an abnormality occurs in the total sum calculation process. It is necessary to prohibit the interrupt processing of FIG.

Therefore, in step S310,
An interrupt prohibition process is performed so that the interrupt process (FIG. 1) by the pulse detection is not executed during the total calculation of the time difference data in the secure RAM 32. Then, step S31
2, a summing RAM (not shown) for storing sum total data of the time difference data in the secure RAM 32 is initialized,
In step S314, the number counter that counts the number of data in the secure RAM 32 is initialized.

The summing RAM for storing the data obtained by summing the time difference data (secured data) in the secured RAM 32 and the number counter for counting the number of secured data are both in the sum calculation means 34. It is assumed to be provided in.

Succeedingly, in a step S316, the secured data is added to the summing RAM, and in a step S318, the secured data number counter is counted (incremented). Then, in step S320, it is checked by referring to the count value of the secured data number counter whether or not all of the secured data numbers (Z / 2) have been added.

If the decision result in the step S320 is NO.
However, if the counting of all the secured data is not completed yet, the process returns to step S316 and the addition process of the secured data is repeated. On the other hand, the determination result of step S320 is Y
If it is ES and addition of all secured data is completed,
In step S322, since the sum calculation is completed, the interrupt prohibition process is canceled and the interrupt enabled state is restored.

In this way, the required time Ti (= ΣΔt (i)) between pulses for a fixed number of pulses (for one stroke) is obtained by obtaining the total calculated value of the secured data. At the end of the total sum calculation routine (FIG. 3), the total sum calculation means 3
The sum total time of all the secured data (that is, the required time from the pulse detection time before the fixed number of times to the current pulse detection time) is secured in the summing RAM in 4.

Next, the main arithmetic processing routine (FIG. 4) for obtaining the engine speed Re1 by the speed calculating means 36 will be described. First, in step S410, a calculation prohibition flag indicating whether or not the engine speed Re1 can be calculated is checked. The calculation prohibition flag is used when a small number of pulses (low rotation) is checked (described later).
In the case where the engine speed Re is set to the fixed data Re2, the value is set.

If the determination result of step S410 is YE.
If S and the calculation prohibition flag are set, the calculation of the engine speed Re1 is impossible, so the main routine of FIG. 4 is immediately terminated. On the other hand, step S4
If the determination result of 10 is NO and the calculation prohibition flag is cleared, in step S412, the required time Ti between pulses for a certain number of pulses (1 / the crankshaft 1 /
2 rotations) and the required time 2Ti for one rotation of the crankshaft 1 is calculated.

As described above, the number of secured pulses (Z /
2) is one stroke of the engine operation stroke (1 of the crankshaft 1
(/ 2 rotations). Then, step S4
In step 14, the reciprocal of the required time 2Ti for one rotation calculated in step S412 is calculated to obtain the calculated value of the engine speed Re1 as in the following expression (3).

Re1 = (1/2) / Ti (3)

The engine speed Re1 can be obtained by an operation using the required time Ti between pulses for a certain number of pulses as in the above equation (3). The engine speed Re1 thus calculated is the final engine speed R
It is output from the data output means 39 as e.

However, with only the arithmetic processing of FIG.
When the required time t (i) between pulses exceeds the measurement range of the free running counter in the ECU 3 and overflows (that is, when the engine speed to be detected is extremely reduced or becomes 0), a fixed number of Since each required time Δt (i) between the latest pulses is secured, there is a risk of causing a calculation abnormality. In order to prevent this, it is necessary to make a minority pulse determination on the number of detection pulses.

Therefore, the interrupt processing by the pulse P (FIG. 2) and the data sum processing in the secure RAM 32 (FIG. 3)
In addition to the engine speed calculation processing (FIG. 4), it is necessary to provide the minority pulse determination processing (FIG. 5) by the determination counter 37. The determination counter 37 that executes the minority pulse determination process has a counter that is cleared when the pulse P is detected in the determination process, and always counts until the next pulse P is detected.

Next, the processing routine (FIG. 5) at the time of determining a small number of pulses (low rotation state) by the determination counter 37 and the data fixing means 38 will be described. First, step S
At 510, the determination counter 37 for small number of pulses is counted (incremented) at a constant timing, and at step S512, it is checked whether or not the count value of the determination counter 37 exceeds the low rotation speed setting time. .

If the determination result D in step S512 is N
If it is O and the count value does not exceed the set time, the determination processing routine of FIG. 5 is immediately terminated. on the other hand,
If the determination result D in step S512 is YES and the count value exceeds the set time, step S514
At, it is checked whether the count value exceeds the second set time (determination threshold value) corresponding to the engine speed Re = 0.

If the determination result D in step S514 is Y
If ES and the count value exceeds the second set time, in step S516, the engine speed R
Fix e2 to 0. On the other hand, if the determination result D in step S514 is NO and the count value does not exceed the second set time, in step S518, the engine speed Re2 is set to a fixed low rotation speed value.

Subsequently, in step S520, the counter of the pointer 33 is initialized to store the secured data in the normal determination after the minority pulse (low rotation) determination.
At this time, the counter of the pointer 33 is the secure RAM 32.
Shows the uppermost point (corresponding to address 0) of the addresses in the table, and secures data between pulses after normal operation recovery
The data storage operation starts from the highest point of 32.

Finally, in step S522, after the normal operation is restored, the sum operation and the engine speed operation are prohibited until a predetermined number (one stroke) of Z / 2 data strings are prepared in the secure RAM 32. Operation prohibition flag is set. In this way, when the count number of the determination counter 37 reaches a certain value (set time), it is determined that the low rotation speed or no rotation speed (0), and the engine rotation speed R
By setting the data of e2 to fixed data of low rotation speed or 0, it is possible to prevent a dead time due to an overflow at the time of measuring the time difference Δt (i).

Further, by interrupting the calculation processing of the engine speed Re1 during the low rotation speed determination period and until the completion of data acquisition for one stroke after the normal detection return,
It is possible to prevent the abnormal calculation result from being output as the engine speed Re.

Example 2. In the first embodiment, the previous detection time t (i-1) and the current detection time t (i) of each pulse P are fetched into the time RAM in the time difference calculation means 31, and then the time difference is calculated. Although Δt (i) is calculated, the previous detection time t (i−1) is held and the time difference Δt (i) is secured simultaneously with the current pulse detection.
2 may be stored.

Example 3. Further, the count value of the judgment counter 37 is compared with the second set time (judgment threshold value), and 2
Although the low rotation state and the zero rotation speed state of the stage are determined, the fixed engine rotation number Re2 may be set to one stage by determining only the low rotation state.

[0077]

As described above, according to the first aspect of the present invention, a pulse provided at a crankshaft of an engine and having a frequency proportional to the engine speed in synchronization with the rotation of the crankshaft is used. Sensor means for outputting for each corner,
The ECU includes an ECU that calculates an engine speed based on a pulse output from the sensor unit, and the ECU includes a time difference calculation unit that calculates a time difference between the pulses and one of the operating strokes of the engine. A sum calculation means for summing a corresponding fixed number of time differences, and a rotation speed calculation means for calculating the engine speed based on the calculated sum of the time differences .
Determine low engine speed based on pulse
Determination means and engine rotation in response to the determination result
Including the data fixing means to fix the number data,
The calculation means is prohibited from the calculation function in response to the determination result.
As a result, the influence of rotation fluctuations during the engine operation process is averaged and suppressed , and stable engine rotation speed calculation accuracy can be achieved only by changing the system control without the need to modify the mechanical or circuit parts. If the time difference data shows a low rotation abnormal value,
Unnecessarily waste time as fixed data for engine speed
There is an effect that an engine speed detecting device that can prevent costs can be obtained.

[0078]

[0079]

[0080]

According to claim 2 of the present invention,
In the item 1 , the determination means has a determination threshold value for determining not only the low engine speed state but also the engine speed 0 state, and the data fixing means responds to the determination result by the engine speed. Since the engine speed is switched to the low rotation speed or the rotation speed of 0, there is an effect that an engine rotation speed detection device with improved reliability of fixed data can be obtained.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing a first embodiment of the present invention.

FIG. 2 is a flowchart showing an interrupt processing routine at the time of pulse detection according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing a routine for calculating a sum of secured data according to the first embodiment of the present invention.

FIG. 4 is a flowchart showing an engine speed main calculation routine according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing a minority pulse determination routine according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a pulse and a summation period according to the first embodiment of the present invention in a time series and diagrammatically, FIG.
Shows the state at the time of high rotation, and (b) shows the state at the time of low rotation.

FIG. 7 is an explanatory diagram showing a memory space of a secure RAM for storing a required time between pulses according to the first embodiment of the present invention together with a pointer.

FIG. 8 is an explanatory diagram showing a rotation speed fluctuation in a general engine operation stroke.

FIG. 9 is a configuration diagram schematically showing a conventional engine rotation speed detection device.

FIG. 10 is an explanatory diagram showing a pulse and a measurement period by a conventional engine speed detection device in a time-series and diagrammatic manner, where (a) shows a state at high rotation and (b) shows a state at low rotation. .

[Explanation of symbols]

1 crankshaft, 2 sensor, 3 ECU, 31 time difference calculating means, 32 securing RAM, 33 pointer, 34
Total calculation means, 36 rotation speed calculation means, 37 determination counter (judgment means), 38 data fixing means, D determination result, P pulse, Re engine rotation speed, Re1 calculated engine rotation speed, Re2 fixed engine rotation speed , Δt (i) time difference, Ti, Ti11, Ti1
2, Ti21, Ti22 Calculated value of total time difference, S21
2 Step of incrementing pointer, S218
Step for calculating time difference, step for inhibiting S310 interrupt operation function, step for step S316, step for calculating sum of time difference data, step S414 for calculating engine speed, steps S512, S514 step for determining low rotation state, step S516 for low speed Step S518, step S518 fixing step at 0 rpm.

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-6-93920 (JP, A) JP-A-1-273857 (JP, A) JP-A-59-28666 (JP, A) JP-A-59- 540 (JP, A) JP 63-241466 (JP, A) JP 58-150864 (JP, A) JP 60-262056 (JP, A) JP 63-235644 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F02D 45/00

Claims (2)

(57) [Claims] 1. A crankshaft of an engine provided in association with
The engine speed is synchronized with the rotation of the crankshaft.
Outputs a pulse with a proportional frequency at each predetermined crank angle
Sensor means, Based on the pulse output from the sensor means,
Engine rotation with ECU for calculating engine speed
In the number detection device, The ECU is Time difference calculating means for calculating the time difference of each of the pulses
When, The one corresponding to one stroke of the operation stroke of the engine
Summing operation means for summing a fixed number of the time differences, The engine based on the calculated value of the summed time difference
Rotation speed calculation means for calculating the rotation speed, Low rotation state of the engine speed based on the pulse
Determination means for determining In response to the determination result, the engine speed data is
Data fixing means for fixing, The rotation speed calculation means responds to the determination result by a calculation machine.
Noh is prohibited Engine speed detection device characterized by
Place 2.The determination means determines whether the engine speed is
Judgment for determining not only the low rotation state but also the 0 rotation state
Has a constant threshold, The data fixing means responds to the determination result with the
Switch the engine speed to low or zero speed
Eru The engine speed according to claim 1, characterized in that
Detection device.