JPS61137071A - Revolution speed detector of multi-cylinder engine - Google Patents

Abstract

PURPOSE:To measure accurately revolution speed of an engine regardless of fluctuation of rotating speed of a cam shaft, by detecting the revolution speed from the time required for revolution of (720/N)Xn deg. CA for the higher revolutions and for 720/N deg. CA for the lower revolutions. CONSTITUTION:In a multi-cylinder engine with an independent plurality of pairs of cam shafts for operating suction and/or discharge value (s) when a number of cylinders of the engine is assumed N a number of pairs of cam shafts (n), at the higher revolutions of the engine, a number of revolutions of the engine V is obtained from the time required T1(sec) for an angle of revolution of the cam shaft corresponding to the revolution of crankshaft, (720/N)Xn deg. CA, i.e. one half of the angle of revolution of the crankshaft by the equation V=60.720.n/360NT1. For the lower revolutions, from the time required T2(sec) for rotation of the crank shaft, 720/N deg. CA, i.e. 360/N deg. of the cam shaft by the equation V=60.720/360 NT2.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for detecting the rotational speed of a multi-cylinder engine,
Particularly suitable for use in 7C multi-cylinder engines, such as V-type engines, horizontally opposed engines, W-type engines, foot-type engines, etc., which have multiple sets of independent camshafts for driving intake valves and/or exhaust valves. The present invention also relates to an improvement in a method for detecting the rotational speed of a multi-cylinder engine when detecting the engine rotational speed from the rotational state of the camshaft.

[Conventional technique vFI] Conventionally, when detecting the rotational speed of a multi-cylinder engine, emphasis was placed on the rotational variation of the crankshaft due to the combustion interval of the engine.
For a 4-cylinder engine, the crank angle is 720'/4-180° (hereinafter abbreviated as OA), and for a 6-cylinder engine, it is the time required for the crank to rotate by 720''/6-120°CA. The average speed was detected to suppress variations in the detected rotational speed (for example, Japanese Patent Laid-Open No. 55-82965). [Problem to be solved by the invention 1] However, the In a multi-cylinder overhead camshaft (hereinafter referred to as OHC) engine with two or more rows of cylinder blocks, each cylinder block is independent to drive the intake valve and/or exhaust valve; engine rotation from the camshaft is When detecting speed, for example, in a 6-cylinder engine, the driving force of the cams of both banks fluctuates at the same period of 240° CA, and the rotation fluctuation period is longer than 720° CA/cylinder failure, so conventional detection methods cannot However, there were problems in that the detected rotational speed varied greatly and errors in ignition timing and injection mm increased. OBJECT OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and is aimed at improving the speed of a multi-cylinder engine equipped with a plurality of independent sets of camshafts for driving intake valves and/or exhaust valves. speed,
It is an object of the present invention to provide a method for detecting the rotational speed of a multi-cylinder engine that can accurately detect the rotational state of a camshaft.

[Means to solve the problem]

The present invention is a multi-cylinder engine equipped with a plurality of independent sets of camshafts for driving intake valves and/or exhaust valves. When the number of sets of camshafts is n, as shown in Figure 1, when the engine is running at high speed, the camshaft is (720/N)Xn''C of the crankshaft.
fMIT at lc required to rotate by a rotation angle corresponding to A rotation, that is, 1/2 rotation angle of the crankshaft rotation.
1 (seconds) to the engine rotation speed V(
rps), and when the engine is running at low speed, the camshaft is rotated by 720/N''CA of the crankshaft, that is, the camshaft is 36
From the W#1lfiT2 (seconds) required to rotate 0/N', the engine rotation speed V(rl)I) is calculated using the following formula (2).
This is a combination of the above objectives. ■-60・720・n/36ONT+...(1)V=
60 ・720/36ONT2 = (2>

[Function] In the case of a multi-cylinder engine equipped with a plurality of independent sets of camshafts for driving intake valves and/or exhaust valves, such as a V-type 6-cylinder engine, the state of fluctuation in the shaft speed of the crankshaft and left and right camshafts. is as shown in Fig. 2, and while the crankshaft speed always fluctuates with a 120° cycle, the camshaft shaft speed changes with a 240° CA cycle when the engine is running at high speeds, and when the engine is running at low speeds. During rotation, it fluctuates at a 120° CA cycle. This is because at high engine speeds, the influence of the mass of the intake and exhaust valves is large, and while the left and right camshafts move independently,
This seems to be because the movements of the left and right camshafts are unified by, for example, a timing belt when the engine is running at low speeds. Therefore, when detecting the engine rotational speed from the rotational state of the camshaft, as in the present invention, when the engine is at high rotational speed, it is (720/N), Xn' CA, and in the case of a 6-cylinder engine, it rotates by 240°CA. Measure the time required for this and calculate the engine speed from this. On the other hand, the delay in the detected rotational speed with respect to the actual rotational speed becomes large, and the fuel injection tlI
720/N when the engine is running at low speeds, which may result in improper engine speed or ignition timing, resulting in decreased engine response.
'CA, that is, in the case of a 6-cylinder engine, the engine rotation speed is detected by measuring between 120@CA. Embodiments Hereinafter, an actual IVA of a V type 6-cylinder single overhead camshaft (hereinafter abbreviated as SOHC) engine to which the present invention is adopted will be explained in detail with reference to the drawings. Electronically controlled fuel injection type V type 6 cylinder 5 to which the present invention is applied
The oda engine is configured as shown in FIG. In FIG. 3, the air sucked from the air cleaner 12 is delivered to the T aflow meter 14 and the accelerator pedal 15.
throttle valve 16, surge tank 18, left and right bank intake boats 20A, 20B, and intake valves 22A, 22B
The combustion chamber 10 of the engine body 10 via an intake passage including
A. Sent to 10B. The combustion chambers 10A, 10B are divided by the left and right banks of cylinder heads IOC, 10D1 cylinder blocks 10E, and pistons nA, nB, and the exhaust gas generated by combustion of the air-fuel mixture is passed through the left and right banks of exhaust valves 2.
4A, 24B, exhaust boats 26A, 28B1, exhaust pipes 28A, 28B, and exhaust pipes 30A, 30B to the atmosphere. The rotation of the crankshaft 40 of the engine is controlled by a crank pulley 42 directly connected to the crankshaft 40, including a timing belt 44, a tensioner 46, and a camshaft pulley 48A.
, is transmitted to the left camshaft 50A and right camshaft 50B via the right camshaft pulley 48B. Camshaft 50A, 50B
The intake valve 22A and the exhaust valve 24A or the intake valve 22B and the exhaust valve 24B are driven to open and close by a cam (not shown) disposed on its shaft. The right camshaft 50B is
It drives the shaft 52A of the destroyer 52, and distributes the high-voltage ignition secondary signal generated by the ignition coil 54 to the spark plugs 56 of each cylinder of the engine. The air flow meter 914 is provided with an intake air temperature sensor 62 that detects the air intake air temperature. The throttle valve 16
is provided with a throttle sensor 64 that detects its opening degree. The cylinder block 10E includes a water temperature sensor 6 that detects the engine cooling water temperature, that is, the engine temperature.
6 are arranged. The exhaust manifold 28A, 2
At the collecting part of 8B, there is an oxygen concentration sensor (hereinafter referred to as o2) that detects the residual oxygen concentration in the exhaust gas for the purpose of detecting the air-fuel ratio.
(referred to as sensors) 68A and 68B are provided. ,
A crank angle sensor 70 is disposed inside the distributor 52 to detect the crank angle of the crankshaft 40 from the rotational state of the distributor shaft 52A. These sensors 14.62.64.66.68A, 68
The output of B, 70 and the voltage of battery 72 are input to an electronic control unit (hereinafter referred to as ECLJ) 74. M
The ECU 74 calculates the fuel injection amount using input signals from each sensor as parameters, and sends an electric pulse having a pulse width corresponding to the calculated fuel injection amount to the injector 80. The injectors 80 are provided in the vicinity of the intake ports 2OA and 20B, corresponding to each cylinder, and fuel from a fuel tank 82 is pumped into the injectors 80 via a fuel pump 84. ECU74 is also
It controls the ignition coil 54. The ECU 74, as shown in detail in FIG.
A central processing unit (hereinafter referred to as CPU) 74A consisting of a processor, a read-only memory (hereinafter referred to as ROM) 74B, a random access memory (hereinafter referred to as RAM) 74C, and an analog-to-digital converter that performs a multiplexer function. (hereinafter referred to as A/D converter)
74D and an input/output boat with a buffer function (hereinafter ■
10 ports) 74E, and a common bus 74F that connects the respective component devices. The air flow meter 14, the intake air temperature sensor 62, and the water temperature sensor 6
6.02 The outputs of the sensors 68A, 68B and the battery 72 are input to the input/D converter 74D. Further, the outputs of the throttle sensor 64 and crank angle sensor 70 are input to the I10 boat 74E. Further, the ignition coil 54 and the injector 80 are connected to the r10 boat 7.
A control command is input from the CPU 74A via 4E. The operation of the embodiment will be explained below. The crank angle sensor 70 detects 1 for every 30 degrees of crank angle.
It is configured to output a pulse signal, and the
The E CtJ 74 uses a routine that generates an interrupt for each pulse according to the flowchart shown in FIG.
When the crank angle is 240 degrees, 1ffiT240cA (
The engine rotation speed NE is determined from the elapsed time T12OCA (when the engine rotates at high speed) or the elapsed time T12OCA when the crank angle is 120 degrees (when the engine rotates at low speed). That is, first, in step n0, the time (in μSaC) of a free run timer (not shown) in the CPU 74A is read. Next, the process proceeds to step n2, and the timer value of rTJ times is read from the RAM 74C, and in step n4, the current timer value is stored in the RAM 74G. Next, the process proceeds to step n6, where the value obtained by subtracting the previous timer value from the current timer value, that is, the time T3 required to move the crank angle of 30 degrees is calculated.
Calculate 0CA (μsec). Then step n8
Proceed to T30CA RAM1i for the past 8 times! [,
All T30CA1-8 are updated once. Next, the process proceeds to step 120, where it is determined whether the previously calculated engine rotational speed NE is equal to or higher than a set value, for example 3000 r91. At high engine speeds when the judgment result is positive,
Proceed to step 122, calculate the total of T30CAI~8, and calculate the time T: 24 required to move the crank angle 240 degrees.
Find 0CA < usea ). Then step 12
Proceed to step 4, and calculate the engine rotational speed NE (rpm) by dividing the constant C obtained by the following equation by 7240OA. C-6Ox (1000) 2x (24G/ 360
)...(3) Here, the coefficient 60 on the right side is a coefficient for converting seconds into minutes, and the coefficient 1000 is μsec
This is a coefficient for converting units into seconds. On the other hand, when the engine speed is low and the determination result in step 120 is negative, the process proceeds to step 126, and T30CA1
~4 is calculated, and the time required to move the crank angle of 120 degrees (fjQT 120CA <useC) is determined. Next, the process proceeds to step 12, and the constant C- shown in the following equation is
The engine rotational speed NE (rpw) is calculated by dividing by Tl20CA. Q= -60x (1000) 2x (120/ 3
60) = (4) After step 124 or 128,
Proceeding to step 130, the calculated engine rotation speed N
E is stored in the RAM 74C, and this routine ends. In this embodiment, when determining T24OCA or T120CA, the latest value is determined every 30 degrees of crank angle, so the detection delay is very small. In addition, T
The method for determining 240CA or T12OCA is not limited to this. In addition, in the illustrated embodiment, T240CA and T12OCA are uniformly switched once depending on the engine rotation speed, but the method of switching between T240CA and T12OCA is not limited to this. For example, hysteresis may be provided by separating the switching rotational speeds when the rotation increases and decreases, or depending on the force n-axis vibration mode, for example, 1000 rpm+ or less (T240CA, 10
00~3000ru Tl 2OCA, 3000rpm
Again, as in T24OCA, it is also possible to switch the rotational speed multiple times. In the above embodiment, the present invention was applied to an evenly spaced explosion type 6-cylinder 5OHC engine, but the scope of application of the present invention is not limited to this, and may be applied to an unevenly spaced explosion engine, a horizontally opposed engine, It is clear that the present invention is equally applicable to W-type engines, foot-type engines, and even double overhead camshaft engines. In addition, T120CA can be used directly without depending on the conventional engine rotation speed.
For items that were controlled using T240CA
It is clear that the scope of the present invention also includes control using TI 2OCA (at high engine speeds) or TI 2OCA (at low engine speeds). (Effects of the Invention) As explained above, according to the present invention, when detecting the engine rotation speed from the rotational state of the camshaft in a multi-cylinder engine equipped with a plurality of independent sets of camshafts, it is possible to Regardless of the engine speed, the variation in detected rotational speed at high engine speeds is reduced, and at low engine speeds, the camshaft speed is 720/N"CA, and the same cycle camshaft rotation angle is 360/N.
720/N' C
The engine rotation speed is determined from the required rotation time of A, and the detection delay when the engine rotates at low speeds can be reduced, making it possible to accurately measure the engine rotation speed regardless of the engine rotation speed. That is, as something similar to the present invention, Japanese Patent Application Laid-Open No. 59-28
In 666, it has been proposed to calculate the rotation speed from the time required to rotate 720'/number of cylinders OA or its multiple angle, but this method does not take into account rotational fluctuations of the camshaft. Variations in the detected value of the engine rotation speed may occur depending on the number of pairs of camshafts, but since the present invention takes into account fluctuations in the rotation of the camshaft, variations in the detected value of the engine rotation speed can be suppressed regardless of the number of pairs of camshafts. be able to. Therefore, it is possible to eliminate variations in fuel injection amount and ignition timing due to variations in engine speed and detection delays, and improve exhaust gas purification performance, fuel efficiency, and responsiveness.
It is possible to prevent engine torque fluctuations, vehicle surges, and knocks. Furthermore, since the variation in ignition timing is reduced, there is no need to provide a margin for knocking, etc., so that the engine output can be improved. In addition, the tension of the timing belt, etc. is extremely strengthened, and the left and right camshafts and crankshaft are integrated, and the phase shift between the camshafts is reduced, making the camshaft rotation fluctuation period 120° CA. Compared to conventional technology, it has the effect of not impairing the durability of the timing belt or increasing engine friction. Furthermore, since both the crank angle sensor and the cylinder discrimination sensor can be disposed on the camshaft, the structure is smaller and cheaper than the previous technology in which the cylinder discrimination sensor was disposed on the camshaft and the crank angle sensor was disposed on the crankshaft. What you can do with such excellent effects.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the gist of the method for detecting the rotational speed of a multi-cylinder engine according to the present invention, and FIG. Fig. 3 is a miniature diagram showing an example of the state of change in the shaft speed of
FIG. 4 is a 4-sectional view showing the overall configuration of an embodiment of the engine.
FIG. 5, which is a block diagram showing the configuration of the electronic control unit used in the embodiment, is a flowchart showing a procedure for calculating the engine rotation speed in the embodiment. DESCRIPTION OF SYMBOLS 10... Engine body, 14... Air flow meter, 16... Throttle valve, 22A, 22B... Intake valve, 24A, 24B... Exhaust valve, 40... Crankshaft, 44... Timing belt, 50A, 50B... camshaft, 54... ignition coil, 64... throttle sensor, 70... crank angle sensor, 74... electronic control unit (ECU), 80... injector .

Claims (1)

[Claims] (1) In a multi-cylinder engine equipped with a plurality of independent sets of camshafts for driving intake valves and/or exhaust valves, when detecting the engine rotational speed from the rotational state of the camshafts,
When the number of engine cylinders is N and the number of camshafts is n, when the engine is at high speed, the camshaft is (720/N) x n
The engine speed is determined from the time required for the camshaft to rotate by 720/N°CA when the engine is running at low speed. A method for detecting the rotational speed of a cylinder engine.