JPS6118838A - Apparatus for detecting knocking of engine - Google Patents

Abstract

PURPOSE:To secure a sufficient signal sampling period without generating erroneous operation by valve closing vibration, by changing the end of the period performing the intake of the output of a vibration detector corresponding to the change in the valve closing timing of a valve apparatus taking variable valve closing timing. CONSTITUTION:The opening and closing timing of a suction valve 15 is controlled so as to be delayed corresponding to the increase in the speed of an engine and detected from the position of an operation rod 39 or the positions of revolving members 33a, 33b. The output of the vibration detector 49 of the engine is sampled for a predetermined period on and after the point of ignition time to judge the knocking state of the engine. At this time, the end of a sampling performing period is changed corresponding to the change in the valve closing timing of the valve apparatus 15 to prevent the a knocking judging means from receiving the effect of the vibration by the valve closing of the valve apparatus.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine knocking detection device. In particular, the present invention relates to a device for detecting knocking by engine vibration.

(Prior Art) A technology is known in which a vibration detector is attached to the cylinder of an engine to detect vibration in each cylinder after ignition and to determine whether or not there is engine knocking.
It is disclosed in Publication No. 2g39g.

By the way, in the case of a multi-cylinder engine, a vibration detector is attached to each cylinder, so after the ignition of one cylinder, vibrations occur in the next cylinder in the ignition order due to the seating of the intake valve, and this seating sensation is caused by Although it is detected by a vibration detector, the intake valve seating vibration is a high-frequency vibration that contains the same frequency components as the vibration caused by knocking, so it is difficult to distinguish the vibration caused by knocking from the intake valve seating vibration. It is difficult. Therefore, normally, an r-t is provided to sample the signal from the vibration detector between the ignition of one cylinder and the seating of the intake valve of the next cylinder in the firing order, and the influence of the intake valve seating vibration is detected. is prevented from entering the detection signal. The reason why only intake valve seating vibration is considered here is that vibration detectors are normally installed on the intake side to avoid interference from exhaust heat, and are not affected by exhaust valve seating vibration. This is because there are few. Therefore, depending on the placement of the vibration detector, 1. It is also necessary to consider the closing timing of the exhaust valve.

(Problem to be solved by the invention) Car engines are used over a very wide range of rotation speeds, so in order to achieve the required performance, valves must be opened and closed at low and high speeds. Timing requirements vary. For example, at low speeds, it is desirable to close the intake valve relatively early to prevent a drop in volumetric efficiency due to intake air blowback, but at high speeds, intake air blowback is not a problem, so the filling amount In order to increase this, it is desirable to close the intake valve relatively late. From this point of view, various mechanisms have been proposed to variably set the opening/closing timing of the valve. (For example, Tokko Sho 3!; g/6 publication, Tokko Sho, r, 2-
3gg1q publication). When a knocking detection device is installed in an engine with variable timing valves, the end of the signal sampling period can be determined according to the intake valve closing timing at low rotation speeds. enters the signal sampling period, and the seating vibration of the valve is sensed. Furthermore, if the end of the signal sampling period is determined according to the closing timing of the intake valve at low rotations, a problem arises in that the signal sampling period becomes too short at high rotations, making it impossible to accurately detect knocking vibrations.

Therefore, it is an object of the present invention to provide an engine knocking detection device that can provide a sufficient signal sampling period for detecting knocking vibration and is not affected by changes in valve closing timing in a variable timing valve mechanism. With the goal.

(Means for Solving the Problems) The present invention provides an engine in which at least one of the intake system and the exhaust system is provided with a valve device with variable valve closing timing.
When determining the knocking state of the engine by sampling the output of the vibration detector for a predetermined period after the ignition point,
The end of the above-mentioned period during which sampling is performed is changed in accordance with changes in the valve closing timing of the valve device so that the knocking determination means is not affected by vibrations caused by the closing of the valve device. In this case, the period during which the output of the vibration detector is sampled is
It is set between the ignition time of one cylinder and the closing timing of the valve device that closes earliest in another cylinder, and the end of the period is advanced when the closing timing of the valve device that closes earliest is earlier. do.

(Function) According to the present invention, the end of the period during which the output of the vibration detector is sampled is determined according to the valve closing timing during high-speed rotation, and as the valve closing timing advances as the engine rotation decreases, The end of the period may be brought forward. At low speeds, the time per cycle of the engine speed increases, so even if the end of the sampling period is brought forward in this way, a sufficiently long sampling period can be taken, and at low speeds, knocking vibration and other Since the level difference from the background vibration is large, there is no problem in detecting the knocking vibration.

(Description of Embodiments) In FIGS. 1 and 2, an engine 1 has a cylinder block 3 and a cylinder head 5 attached to the upper part of the cylinder block 3. Cylinder block 3 has 2 cylinders 3&.

3b, 3c, and 3d are formed in series, and each cylinder has a piston 7 disposed within the cylinder so as to be able to freely reciprocate. The cylinder head 5 has cylinder bores 3a*3b
, 3 a * 3 d, and an intake port 11 and an exhaust port 13 are formed to open into each combustion chamber recess 9 . Intake port 1
1 is combined with an intake valve 15, and the exhaust port 13 is combined with an exhaust valve 17.

The intake valve 15 has a valve stem 151 extending above the cylinder head 5, and is pushed in the valve closing direction by a spring 19 that engages with the valve stem 15a.Similarly, the exhaust valve 1
7 has a valve stem 17a, which is pushed in the valve closing direction by a spring 21 that engages with the valve stem 17m.

In order to periodically open the intake valve 15, a camshaft 23 is arranged parallel to the row direction of the cylinders 3a+3b, 3e, and 3d. Similarly, in order to periodically open the exhaust valve 17, the camshaft 25 The cylinders are disposed on the opposite side of the camshaft 23 and parallel to the camshaft 23, with the cylinders sandwiching the cylinders in between. Pulleys 27 and 29 are fixed to the ends of the camshaft 23.25, respectively, and the camshaft 23.25 is synchronized with the engine crankshaft by means of a tie belt 31 that is hooked onto these pulleys 27 and 29. It is driven by The cam 23 is attached to the cam shaft 23.
a, 23b, 23c, and 23d are cylinder Zea 3, respectively.
They are formed at positions corresponding to a, 3b, 3a, and 3d. Further, on the camshaft 23, a rotational member 33a is supported at a position between the cams 23a and 23b, and a rotational member 33b is supported at a position between the cams 23c and 2jd so as to be rotatable around the camshaft 23. ing. A rotating member 33a is shown in FIG. 1, and this rotating member 33& has a cylinder 73
Tappet 35m at the position corresponding to the intake valve 15 for a.
is arranged to be freely slidable in the axial direction, and the upper surface of the tappet 35& is in contact with the cam 23a, and the lower surface thereof is in contact with the end of the valve stem 15a of the intake valve 15, respectively. Therefore, the intake valve 15
is opened and closed by the cam 23a via the tappet 35m. Although not shown in the figure, a similar tappet is provided on the rotating member 33a at a position corresponding to the intake valve 15 of the cylinder bore 3b, and this intake valve is opened and closed by the cam 23b via the tappet. be done.

Similarly, the rotating member 33b has a cylinder there 3c.

Tappets are provided at positions corresponding to the intake valves 15 of 3d, and the intake valves 15 of these cylinder bores are connected to the cam 2.
It is opened and closed by 3c and 23d.

The upper parts of the rotating members 33a and 33b are connected to each other by a connecting rod 37 parallel to the camshaft 23, and the connecting rod 37 has a first
Actuation rod 39 is engaged as shown. Operating rod 39
extend perpendicularly to the camshaft 23, and by moving in the axial direction, the rotating members 33a, 33b can be rotated around the camshaft 23. An actuator 41 is provided for axially moving the actuating rod 39, which actuator 41 determines the axial position of the actuating rod 39 depending on the engine speed and accordingly moves the pivoting member 33.
It acts to determine the rotational position of a, '33b. In the illustrated mechanism, the rotating member 33a.

The opening/closing timing of the intake valve 15 changes depending on the rotational position of the intake valve 33b. In this example, the opening/closing timing of the intake valve 15 is controlled to be delayed as the engine speed increases. The opening/closing timing of this intake valve can be detected by detecting the position of the operating rod 39 or the rotating members 33a, 33b.

The camshaft 25 on the exhaust side has cylinders 3a, 3b, 3.
Cams 25a and 25b are placed at positions corresponding to c and 3d, respectively.
, 25c, 25d are provided, and these cams 25a, 25
b, 25c, and 25d open and close the respective exhaust valves 17 via tappets 43.As shown in FIG.
An intake passage 45 is connected to the intake port 11.
A fuel injection valve 47 is arranged at 5. On the upper part of the cylinder block 3, on the intake side, there are cylinder grooves 3a, 3.
．． Vibration detector 4 is placed at the position corresponding to each of b, 3c, and 3d.
9 is attached to detect vibrations generated in the cylinder block 3.

FIG. 3 shows a knocking detection circuit, in which the output of the vibration detector 49 is amplified by an amplifier 50 and filtered by a filter 51.
passed through. The output of the filter 51 is passed through a seventh dart circuit 53 to become a knocking signal on the one hand, and is passed through a back ground signal forming circuit 57 through a seventh dart circuit 55 on the other hand. The pack ground signal forming circuit 57 includes a rectifier circuit 57m that receives the output of the first Huguthe circuit 55, an integrator circuit 57b that integrates the output of the rectifier circuit 57m, and an amplifier 57a that amplifies the output of the integrator circuit 57b.
It consists of The knocking signal from the first gate circuit 53 and the background signal from the amplifier 57c are input to a comparator 59 and compared. Outputs a knocking determination signal. Comparator 5
The knocking determination signal from 9 is input to an integrator 61 where it is integrated, and the output of the integrator 61 is amplified by an amplifier 63.

A control circuit 65 consisting of a microcomputer is provided to determine the ignition timing of the engine, and the output of the knocking detection circuit is guided to this control circuit 65. The control circuit 65 receives as input an ignition signal, a crank angle signal from the crank angle sensor, an intake pressure signal, and an intake valve timing signal indicating the opening/closing timing of the intake valve 15, and outputs an ignition timing control signal to the ignition timing control circuit 67. do. Control circuit 65
The ignition signal inputted to the ignition signal indicates the point in time when ignition is performed, and the control circuit 65 calculates the engine rotation speed based on this ignition signal. A timer 69 is provided in combination with the control circuit 65, and this timer 69 is connected to the dart circuit 5.
In addition to performing opening/closing control of 3.55, an integral circuit 57b,
Reset circuit 71.73 for resetting 61
It also controls the

Figure D shows the opening/closing timing of the intake valve 15 and the exhaust valve 17 in the engine of this example, and shows the cylinders formed by cylinder bores 3aH3b+3c13d, respectively. No. 3. It is displayed as the second cylinder. In the figure, ignition is the first. In this example, the operation is carried out in the order of 3rd, 3rd and 3rd cylinders, where the solid line shows the opening period of the intake valve and the broken line shows the opening period of the exhaust valve. Ignition is shown by the arrow in the figure. For example, when ignition occurs in the first cylinder, it starts with a slight delay from the time of ignition, and then starts at the intake valve of the cylinder in the order in which ignition occurs, that is, the third cylinder. A period A that ends just before the valve closing timing is a sampling period in which the signal from the vibration detector 49 is captured. Here, if the engine speed decreases and the timing of the intake valve is advanced, for example, as shown by the dashed line in FIG. 1, the end of the sampling period is advanced as shown by B in the diagram. 1f-) circuit 53 and cogut circuit 5
5 may be opened at the same time, and the rectified and integrated signal may be used as the background signal.

Another method is to open the first dart circuit 55 in the first half of the sampling period and input the signal from the vibration detector 49 to the pack ground signal forming circuit 57, and open the first dart circuit 53 in the second half of the sampling period. It may be opened to pass the knocking signal to the comparator 59.

FIG. 5 is a 70-chart showing the operation of the control circuit 65, which is set to allow an interrupt by the output of the knocking detection circuit before starting the basic routine. This interrupt is performed immediately when the output of the knocking detection circuit exceeds a predetermined value.

In the basic routine, first, the ignition timing correction term ΔIg and the correction coefficient K are set to zero. Next, the intake valve timing Pv is read, and a sampling period GA corresponding to the engine crank angle is calculated based on the read value Pv. Thereafter, the engine rotational speed signal N obtained based on the ignition signal and the engine intake pressure signal (3) are read, and a sampling period Gt in units of time is calculated based on the read values.

Furthermore, the reset time interval Rt from the engine rotational speed signal
After calculating, the sampling time GA' and reset time Rt are set in the timer 69. Based on this setting, the timer 69 opens the first dart circuit 53 and the a-th gate circuit 55 in accordance with the aforementioned sampling period 7'. The reset time Rt is set at an appropriate time after the sampling period for one cylinder ends and before the next cylinder in the firing order starts firing.

The control circuit 65 includes a map 65& that stores the basic ignition timing Igo determined according to the engine operating conditions, and sets the basic ignition timing 1gO based on the engine speed signal N and intake pressure signal VB read in advance. Read. - then the formula Ig = igo-△rg
The ignition timing Ig is determined by calculation based on , the crank angle signal CA is read, and ignition is performed when the crank position and ignition timing are compared and the ignition timing matches the ignition timing. When ignition is performed, / is added to the correction coefficient k, and this newly set correction coefficient k
Then, the ignition timing correction term △1g is newly set by performing calculation based on the formula Δrg = ∆rg-e-''.Since the correction term ΔIg is initially set to zero, this correction term also changes by ignition. There is no change in Δrg, so the ignition timing remains unchanged as shown at a in FIG.

When knocking is detected, an interrupt routine is executed. In this interrupt routine, the output Vk of the knocking detection circuit is read, and the equation △Ig ; △rg
A correction term Δrg is obtained by calculation based on +c·Vk, and at the same time, the correction coefficient is set to zero. Since the above-mentioned basic routine is performed, the ignition timing Ig is delayed as shown by b in FIG. 6. If knocking does not occur in this state, the correction term ΔI
g decreases as the number of ignitions increases by a value determined by the formula ΔIg=ΔIg−e. Therefore, the ignition timing is gradually advanced as shown by C in the figure.

(Effect) In the present invention, the knocking determination means detects the vibration detector according to the change in the valve closing timing of the valve device with variable valve closing timing so that the knocking determination means is not affected by the vibration caused by the closing of the valve device with variable valve closing timing. Since the output is taken in and the end of the nine periods is changed, a sufficient signal sampling period can be ensured without causing malfunctions due to valve closing vibration.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of an engine equipped with a variable timing valve system, Fig. 1 is a horizontal sectional view thereof, Fig. 3 is a block diagram of the knocking detection circuit, and Fig. D is the relationship between valve timing and sampling period. 3(a) and 3(b) are flow charts showing the operation of the control circuit, and FIG. 6 is a diagram showing the ignition timing. 11...Intake port, 15...
...Intake valve, 23...Camshaft, 33a
・・・・・・・・・Rotating member, 35 &・・・・・・・・・
・Tappet, 49... Vibration detector,
53.55... Dirt circuit, 65...
...... Control circuit Figure 4 (a) Section 5 (b) Delay

Claims (3)

[Claims] (1) An engine knocking detection device comprising a vibration detector attached to the engine body and a knocking determination means for determining the knocking state of the engine based on the output of the vibration detector during a predetermined period after the ignition point, At least one of the intake system and the exhaust system is provided with a valve device with variable valve closing timing, and the knocking determination means adjusts the closing timing of the valve device so as not to be affected by vibrations caused by the closing of the valve device. An engine knocking detection device comprising means for changing the end of the predetermined period in accordance with a change. (2) In the knocking detection device of item 1, the engine is a multi-cylinder engine having a plurality of cylinders, vibration detectors are attached to all the cylinders, and the predetermined period in the knocking determining means is set at the ignition point of each cylinder. and the closing timing of the valve device that closes earliest in another cylinder, and the end of the predetermined period is advanced when the closing timing of the valve device that closes earliest is advanced. Device. (3) In the knocking detection device according to item 2, the variable valve closing timing valve device is provided in the intake system, the vibration detector is attached to the engine body on the intake system side, and the knocking determining means The knocking detection device is characterized in that the predetermined period is determined from the ignition time of each cylinder to the closing timing of the variable valve closing timing valve device that closes the other cylinder earliest.