JPH02140446A - Top dead center detecting device for engine - Google Patents

Abstract

PURPOSE:To detect an accurate crank angle to a top dead center by providing at least four protrusions at a preset angle at the position corresponding to the top dead center of a revolving element on a crank shaft and a top dead center sensor opposite thereto to measure an interval between pulses of sensor signals. CONSTITUTION:Four pulse generating protrusions 3 have the first protrusion 3a fitted nearly in position at 15 deg. to a top dead center, the second protrusion 3b at 5 deg. to the same, the third protrusion 3c at 5 deg. past the same and the fourth protrusion 3d at 15 deg. past the same. Pulses detected by a top dead center sensor 4 are fed to an arithmetic means 6. Pulse periodical data read by the counter 61 of the arithmetic means 6 are computed at a rotational speed in a CPU 62 by an arithmetic algorithm stored in a memory 63 and a crank angle to a top dead center is enumerated. It is thus possible to determine the angle of the first protrusion 3a to the top dead center. By such constitution that a preset crank angle is detected at which the revolving speed of a crank angle gets zero, adjustment and compensation are not necessary and a crank angle to the top dead center is detectable regardless of engine speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for detecting the top dead center of the crank angle of a rotating engine.

[Conventional technology]

During engine operation, accurately detecting the crank angle or "second dead center" is especially important for electronically controlled engines, as it is important to accurately detect the ignition or injection timing.
<11, (Extremely important to become a cow!)

As shown in Fig. 5, a well-known top dead center detection device for an engine since ancient times has a stamp 9 on the circle +511- of a pulley 8 attached to the crankshaft 7, indicating the top dead center position of the crankshaft 7. One protrusion 11 is provided, a top dead center sensor 12 is attached opposite the position of the protrusion II when the crankshaft 7 reaches the top dead center position, and a pointer is attached to the engine body (not shown). 10 indicates the position when the stamp 9 reaches the top dead center. Further, the top dead center sensor 12 can be finely adjusted in position, and the generated pulses are transmitted via a controller 14 and connected to a timing light 15 so as to emit light.

In operation, when the protrusion 11 passes in front of the second dead center sensor I2, a pulse is generated from the sensor I2, which causes the timing light 15 to emit light via the controller 14 to illuminate the pointer 10 and the marking 9. . If pointer io and marking 9 appear misaligned, top dead center sensor 1
2 is installed by adjusting the position so that the pointer 10 and the marking 9 appear aligned.

In order to perform such work on the I11 vertical line, it is necessary to install the sensor and make fine adjustments, and the distance between the sensor and the protrusion changes due to vibration, making it difficult to perform accurate detection. There was a drawback.

For this reason, a device as shown in Japanese Unexamined Patent Publication No. 59-87277 has been proposed. This device, as shown in Figure 6,
71- to the ring gear 17 in the clutch housing I6;
Part 1'? a is provided, and the 2Hy sensor 18 is disposed opposite to the tooth portion 17a.

Electromagnetic sensor 18 generates a ring gear signal and amplifier 19
It is sent to the top dead center detection device main body 20 via.

An ignition timing meter 21 is connected to the first dead center detection device main body 20 as a seat value device, and an idle roughness meter 22 as an evaluation device is connected in parallel with the ignition timing meter 21. History 1-The ignition signal from the ignition sensor 25 is input manually to the dead center detection device main body 20 via the amplification 2323, and the signal from the top dead center detection device main body 20 is inputted via the amplification 'J'i24. timing light 2
6 outputs illumination light toward an ignition timing mark provided on the engine body.

The ring gear signal generated from the electromagnetic sensor 18 has a waveform as shown in FIG.
The signal is shaped into a rectangular signal as shown in FIG. This ring gear signal indicates that ring gear 17 is 1
While rotating, a corresponding number is output due to the teeth, and the counter circuit generates a pseudo top dead center signal every time it counts a predetermined number of ring gear signals and a clock for fine adjustment, and outputs a timing light. Output to 26.

When a deviation occurs between the generated pseudo-hi dead center signal and the ignition time mark provided on the engine body, a ring gear (No. 3 switch (not shown) for correcting the predetermined count) is activated. , and a switch (not shown) for correcting a predetermined count of the clock, the fine adjustment pulse shown in FIG. 7(c) is generated and the fine adjustment pulse shown in FIG.
When the dead center signal occurs as shown in the figure! 111 is shifted.

[Problem to be solved by the invention]

The problem with this type of dead center detection device is that it requires troublesome engineering work to correct the deviation between the top dead center detection signal and the top dead center crank angle. was there.

Therefore, one object of the present invention is to realize a top dead center detection device for an engine that does not require adjustment for detecting the top dead center crank angle.

[Means to solve the problem]

At least four protrusions provided at a predetermined angle at a position corresponding to the dead center of the rotating body on the crankshaft; a top dead center sensor attached opposite to these protrusions; and a top dead center sensor. and calculation means for measuring the inter-pulse interval of the pulse signal generated by the engine and detecting a predetermined top dead center crank angle at which the change in crank angular velocity becomes zero.

(Function) In the present invention, the angular velocity (rotational speed) of the engine crankshaft is changed every 11 rotations 180° as shown in FIG.
F Definitely changes. Therefore, it can be seen that by detecting this change in angular velocity, the top dead center crank angle can be detected at 11Efft.

For this reason, a top dead center sensor that faces at least four protrusions provided at positions corresponding to the dead center of the rotating body of the crankshaft 1- emits 4! : The generated pulses are manually input to the calculation means.

The calculation means measures the inter-pulse interval of the pulses, determines the angular velocity of the crankshaft from this inter-pulse interval, and further calculates the point in time when the change in the angular velocity of the crankshaft becomes zero,
It is detected as the top dead center crank angle, which is unrelated to the rotation speed.

〔Example〕

FIG. 1 shows an example of an F dead center detection device according to the present invention. In this embodiment, a crankshaft l, a rotating body 2 connected to the crankshaft l, and a rotating body 2 connected to A protrusion 3 consisting of four protrusions 3a to 3d is provided, a dead center sensor 4 is provided opposite to the protrusion 3 and generates pulses, and a frame 5, which holds the top dead center sensor 4, is attached to the frame 5, The counter 61 connected to the point sensor 4, the CPIJ 62 and the memory (RO
M/RAM) 63, and a calculation means 6 for calculating the input pulses and detecting the top dead center crank angle.

The operation of this embodiment will be explained below.

As shown in FIG. 2, the engine during operation exhibits a minimum angular velocity, with the angular velocity changing precisely every 180° half revolution. If we focus on one piston, this point will occur twice during one rotation, at the dead center at - and at the bottom dead center, but as for the crankshaft 1, one of the pistons will always be at the dead center at -. , it is sufficient to detect this point. In this embodiment, four pulse generating protrusions 3 are attached at positions corresponding to the top dead center, the first protrusion 3a is located at i5° before the top dead center, and the second protrusion 3b is attached at a position corresponding to the top dead center.
- The third protrusion 3C is attached at 5 degrees before the top dead center, the fourth protrusion 4d is attached at 15 degrees after the top dead center.

The pulses detected by the top dead center sensor 4 are sent to the means 6 of FIG. In the calculation means 6, as shown in the flowchart of FIG. 3, the counter 6! Pulse frequency loaded into! The S1 data (ST, S1) is processed by the CPU 62 using an arithmetic algorithm that is stored in the memory 63 and will be described later.
The rotational speed is calculated (step 32), and the top dead center crank angle is calculated (step S3).

Next, to explain the above calculation algorithm using FIG. 4, the crank angle between each protrusion is equal to d 1datX
L+, the inter-pulse interval of the pulses that are in contact with L and K, respectively.
, Lz, L:l 1sec, and the rotational speed of the protrusion 3 between M contact pulses is Vl, respectively.
V2, V:+1rev/5ecl, it is expressed as, and the speed v9. v2. Since ν is the average rotational speed between each pulse, the crank angle at that time can be considered to be at the center between each pulse.

In the equations written in (1) and (-), the rotary speed is expressed as the same rotational speed, but this is exactly the same even if expressed as the angular velocity.This is to avoid indicating that the top dead center is independent of the rotational speed, as will be described later.

Therefore, the angle between each pulse is d, and the crank angle from the first pulse of Ia (intermediate position between pulses) is XI, XI, If Xz, these crank angles at intermediate positions between each pulse are as follows.

v-a x21-bx +C, and in order to find the coefficients a, b, and c, the following continuous equations can be solved using the constants v1 to V and x1 to X.

Vl -ax, ” + bx, I-c
...1llVz -a xt ” 10b XI
+C--(2)vx -a xff'L b XI4-
c -- (3) In such a quadratic function, finding the minimum point of the crank rotation speed is equivalent to finding the second dead center, so we can find X when the -order differential d v / d x -0. All you have to do is ask.

When calculating d v / d x from the general formula of the order number, the crank angle is Xl + when the rotational speed is V,
! + When it is v3, it becomes X. As can be seen from FIG. 4, the angular velocity at top dead center, that is, the rotational speed, is approximately a quadratic function, so if the crank angle X and the rotational speed V are known, the coefficients of the quadratic function can be determined. That is, if both are expressed by a general formula of a quadratic function, it becomes x. Therefore, from (1) to (3) 2, coefficients a, b
, c and then -b/2a, the top dead center crank angle X can be found.

Therefore, X, = (1/2. XI =: (d/2.
Since X:l -5d/2, these can be expressed as (1) to (
3) Substituting it into the equation and subtracting it gives the equation fia,
The equation of only b, c and angle d is given.

V2-V, =2 a d" + b d =...
・(5) Vz″′Vz=4ad″Ibd---(
6) Then, from equations (6)-(5), the following equation is obtained.

V, -2V2 tv, = 2ad” Therefore, Further, by transforming equation (5), the next generation can be obtained.

By substituting equation (7) into (8)2, the following equation is obtained.

2av, -2vz+V+ Here, from equation (4), x = -b/2a, so the dead center crank angle X can be found by the following equation.

That is, the top dead center crank angle Using V2°V, C
I) It can be seen that if tJ 62 is calculated using equation (9) stored in the memory 63, the angle X from the first protrusion 3a to 1-dead center can be determined.

In Equation (9) for determining top dead center in this manner, the demensicons of the numerator and denominator are the rotational speeds, so the top dead center crank angle can be determined regardless of the engine rotational speed.

In the present invention, as long as the numerical value of the spacing between the protrusions is known in advance, the spacing between the protrusions may not be equal. Furthermore, in order to increase the detection accuracy, the number of protrusions may be increased and the approximation may be performed using a higher-order function. It is also possible to increase the number of protrusions and calculate by the least squares method.

Furthermore, the above methods can also be combined.

[Effects of the Invention] As described above, according to the present invention, at least four shafts are provided at a predetermined angle at a position corresponding to the dead center of the rotating body of the crankshaft.
The two protrusions measure the inter-pulse heat of the pulse signal when they pass the top dead center sensor placed opposite each other, and detect the predetermined crank angle at which the rotational crank angular velocity becomes zero. Without the need for correction, ■- Dead center crank angle can be detected regardless of rotation, and when igniting! 11
Evaluation of 1 can also be done in the cage.

[Brief explanation of the drawing]

1 is a diagram showing an embodiment of the engine dead center detection device according to the present invention. FIG. 2 is a graph showing the relationship between the crank angle and angular velocity (rotational speed) of the engine. FIG. 4 is a flowchart of a program executed by the calculation means of the present invention; FIG. 4 is a diagram showing the angular velocity near top dead center used in the calculation means of the invention; FIG. Dead point sensor: A diagram showing the configuration of η. FIG. 6 is a diagram showing the configuration of a conventional dead point detection device according to Japanese Patent Application Laid-Open No. 59-87277. FIG. 2 is a waveform diagram illustrating the operation of the conventional top dead center detection device according to the above publication. In FIG. 1, 1 is a crankshaft, 2 is a rotating body, 3 is a protrusion, 4 is a top dead center sensor, [j is 6ii'r, and the γL stage is not shown.

Claims (1)

[Claims] At least four protrusions provided at a predetermined angle at a position corresponding to the top dead center of the rotating body on the crankshaft, a top dead center sensor attached opposite to the protrusions, and the top dead center sensor. A top dead center detection device for an engine, comprising: arithmetic means for measuring the interval between pulses of a pulse signal to detect a predetermined top dead center crank angle at which a change in crank angular velocity becomes zero.