JP2543577Y2 - Internal combustion engine rotational speed measurement device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring a rotation speed of an internal combustion engine used as a parameter for controlling a fuel injection amount and a shift control of an internal combustion engine of an automobile.

2. Description of the Related Art A crank angle sensor provided in connection with an internal combustion engine derives a top dead center signal at every 180-degree crank angle when the internal combustion engine is, for example, a 4-cylinder 4-cycle internal combustion engine. A rotation signal is derived for every 30 degree crank angle. The pulse cycle of the top dead center signal and the rotation signal is measured by a clock signal having a cycle sufficiently shorter than the signal. The rotational speed of the internal combustion engine is calculated based on the measurement result, and is used for the fuel injection amount control, shift control, and the like.

In measuring the rotational speed of the internal combustion engine used as described above, the clock signal shown in FIG. 5 (1) is compared with the clock signal shown in FIG. 5 (2) in a typical prior art. As described above, the number of clock pulses is measured for each cycle W1 of the top dead center signal. In another conventional technique, the fifth
As shown in FIG. 3 (3), a method of measuring the number of clock pulses over a predetermined plurality (four in this example) of top dead center signal periods W2 is used.

According to the method of measuring the number of clock pulses for each cycle W1 of the top dead center signal, a rapid change in the rotation speed of the internal combustion engine, that is, a good response to the change in the cycle W1. The number of clock pulses can be measured. On the other hand, since the measurement cycle is short at the time of steady rotation of the internal combustion engine or the like, the cycle indicated by reference numeral W1a in FIG.
In spite of the fact that the measurement period is the same as the period indicated by, the number of measured pulses differs between 5 and 4, for example, as is apparent from FIG. Is inferior.

In the method of measuring the number of clock pulses over the cycle W2 of a plurality of top dead center signals shown in FIG.
The average value of the pulses over a relatively long period is obtained, and the measurement accuracy is improved. However, it is not possible to follow a rapid change in the rotation speed of the internal combustion engine, and the response is poor.

The purpose of the present invention is to measure the rotation speed of the internal combustion engine in a relatively short cycle with good responsiveness, and in a relatively long cycle with high measurement accuracy. It is an object of the present invention to provide an internal combustion engine rotational speed measurement device capable of measuring the internal combustion engine rotational speed by using a measurement result by a method according to a use.

Means for Solving the Problems The present invention provides a pulse generating means for generating a pulse at a constant crank angle of an internal combustion engine, a clock signal generating means for generating a clock signal of a constant cycle, and a pulse output from the pulse generating means. First measuring means for measuring the number of clock signals output from the clock signal generating means while the next pulse is output after the first pulse is output; and a plurality of predetermined pulses after the pulse is output from the pulse generating means. A second measuring means for measuring the number of clock signals output from the clock signal generating means while the clock signal is output; and a measured value corresponding to one cycle of the pulse measured by the first measuring means is an internal combustion engine. It is used for control that needs to follow a rapid change in the rotation speed of the motor, and the measured numerical value corresponding to a plurality of cycles of the pulse measured by the second measuring means is: Selecting means for selecting a measurement value suitable for the control content in accordance with the control content so that a high-precision one of the rotation speed of the internal combustion engine is used for the required control. It is a rotation speed measuring device.

According to the present invention, a pulse is generated from the pulse generating means at every constant crank angle of the internal combustion engine, and a clock signal having a constant period is generated from the clock signal generating means. The pulse from the pulse generating means and the clock signal from the clock signal generating means are commonly provided to the first measuring means and the second measuring means, and the first measuring means outputs the pulse from the pulse generating means. The number of clock signals output from the clock signal generating means is measured while the next pulse is output after that, and the second measuring means measures the number of clock signals output from the pulse after the predetermined number of pulses have been output since the pulse was output. The number of clock signals output from the clock signal generating means is measured.

The selecting means uses the measured value corresponding to one cycle of the pulse measured by the first measuring means for control which needs to follow a rapid change in the rotation speed of the internal combustion engine, and The measurement values corresponding to the plurality of cycles of the pulse measured in step (1) are selected according to the control contents so that the measurement values with high accuracy of the rotation speed of the internal combustion engine are used for the control. Therefore, regardless of the rotational speed of the internal combustion engine, the calculation of the fuel injection amount can always be performed with good responsiveness and high accuracy.

FIG. 1 is a block diagram showing an electrical configuration of an embodiment of the present invention. From the crank angle detector 1 serving as a pulse generating means, a pulse shown in FIG. 2B is generated at every constant crank angle of the internal combustion engine, for example, at each top dead center, and is derived to the line 2. This crank angle detector 1 detects the crank angle by, for example, fixing a permanent magnet piece to a crankshaft and detecting the magnetic force of the permanent magnet piece by a sensor attached to a fixed position of the internal combustion engine. Alternatively, an ignition signal derived according to the rotation of the crankshaft may be detected.

The pulse from the crank angle detector 1 is commonly input to the first counter 3 and the second counter 4 via the line 2. A clock signal from a clock signal generating circuit 6 is commonly input to the first and second counters 3 and 4 via a line 5. As shown in FIG. 2 (1), the clock signal generated by the clock signal generating circuit 6 is derived from a pulse having a period sufficiently shorter than the pulse from the crank angle detector 1.

The first counter 3 counts the number of pulses of the clock signal for each cycle of the pulse from the crank angle detector 1 indicated by reference numeral W1 in FIG. 2 (2). On the other hand, the second counter 4 counts the number of pulses of the clock signal over a predetermined period W2 of the pulse (for example, four times the period W1).

Thus, the count value indicating the rotation speed of the internal combustion engine measured by the first counter 3 is input from the line 7 to the fuel cut control unit 9 of the fuel injection control device 8. The count value of the second counter 4 is given from the line 10 to the fuel injection control device 8 and is input to the fuel injection amount control unit 11 for calculating the fuel injection amount based on the rotational speed measured with high accuracy. You.

The fuel injection amount control unit 11 operates the actuator 13 via the switch 12 to supply fuel to the internal combustion engine in accordance with the fuel injection amount obtained using the count value of the second counter 4. The fuel cut control unit 9 detects the opening of the throttle valve by a sensor (not shown), and in a state where the throttle valve is closed, the fuel cut rotation whose rotation speed obtained from the count value of the first counter 3 is predetermined. When the speed exceeds the speed, the switch 12 is shut off for reasons such as improved fuel efficiency. As a result, the operation control of the actuator 13 by the fuel injection amount control unit 11 is prohibited, and the supply of fuel is cut off. The counters 3 and 4 and the fuel injection control device 8
May be constituted by one microcomputer.

In the above-described configuration, when the rotation speed of the internal combustion engine decreases due to a decrease in the slope of the downhill, the rotation speed further decreases and the vehicle speed decreases while the fuel supply is cut off. At a time point when the predetermined lower limit value is reached, the switch 12 is turned on and the fuel supply is immediately restarted.

If the resumption of the fuel supply is delayed, a so-called stall phenomenon occurs, and therefore, particularly when the crankshaft and the wheels are connected by an automatic transmission, the internal combustion is caused by the slip of the automatic transmission. The engine has stopped, and despite running at a high speed of, for example, about 80 km / h,
There is a problem that the starter motor must be started. However, by determining the cutoff / supply of the fuel supply based on the count value from the first counter 3 having good responsiveness, the above-described problem can be solved.

FIG. 3 is a flow chart for explaining the counting operation of the first and second counters 3 and 4, and each time the pulse of the top dead center signal is derived from the crank angle detector 1, an interruption process is performed. It is performed as. In step n1, the input time t (i-1) of the previous pulse is subtracted from the input time ti of the current pulse from the crank angle detector 1, and the pulse period W1 is calculated. In step n2, the current interrupt time
ti is the previous interrupt time t (i-1) for the next calculation
Set as

At step n3, the count value C of the second counter 4 becomes 1
In step n4, it is determined whether or not the count value has become 0, that is, whether or not the top dead center signal has been inputted four times in advance. If not, this interrupt processing is terminated and the original It returns to operation, and if so, goes to step n5. At step n5, the second counter 4 updates the time t (i-1) updated at step n2.
From the time t (i-4) earlier by the predetermined number of pulses 4
Is subtracted to obtain the cycle W2. In step n6, the current interrupt time t (i-1) is set as the previous interrupt time t (i-4) for the next calculation. In step n7,
The first and second counters 3, 4 are reset and return to the original operation.

FIG. 4 is a flowchart for explaining the operation when the detection results of the counters 3 and 4 are selected and used. At step m1, it is determined whether or not the use of the measured count value requires accuracy, and if so, at step m2, the second counter measured over a relatively long period W2. A count value of 4 is selected,
Otherwise, in step m3, the count value measured by the first counter 3 is selected, and the operation ends.

As described above, in the method for measuring the rotation speed of the internal combustion engine according to the present invention, the count value of the first counter 3 having a good response to the fluctuation of the rotation speed of the internal combustion engine measured at every relatively short measurement cycle W1. And the count value of the second counter 4 with high measurement accuracy measured over a relatively long cycle W2, as appropriate, as shown in FIG. 4, depending on the application in which these count values are used. Thus, the count value on the side adapted to the purpose of emphasizing responsiveness or measurement accuracy can be used, and the functionality can be improved.

Effect of the Invention As described above, according to the present invention, the time of one cycle of the pulse from the pulse generation means having a cycle corresponding to the rotation speed of the internal combustion engine is measured by the first measurement means using the clock signal. In order to shut off fuel injection, so-called fuel cut control, etc., it is necessary to follow a rapid change in the rotation speed of the internal combustion engine, so that engine stall is always prevented regardless of the rotation speed of the internal combustion engine. It becomes possible. The second measuring means measures the time of a plurality of cycles of the pulse from the pulse generating means using a clock signal, and performs control such as control of the fuel injection amount which requires a high-precision internal combustion engine rotational speed. Therefore, the calculation of the fuel injection amount can always be performed with high accuracy regardless of the rotation speed of the internal combustion engine.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of an embodiment of the present invention, FIG. 2 is a waveform diagram for explaining the counting operation of a first counter 3 and a second counter 4, and FIGS.
FIG. 5 is a flowchart for explaining the operation, and FIG. 5 is a waveform diagram for explaining the counting operation of the prior art. 1 ... Crank angle detector, 3 ... First counter, 4 ...
2nd counter, 6 clock signal generating circuit, 8 fuel injection control device, 9 fuel cut control unit, 11 fuel injection amount control unit, 12 switch, 13 actuator

Claims (1)

(57) [Scope of request for utility model registration] 1. A pulse generating means for generating a pulse at every constant crank angle of an internal combustion engine, a clock signal generating means for generating a clock signal having a constant period, and a next pulse after a pulse is output from the pulse generating means A first measuring means for measuring the number of clock signals output from the clock signal generating means while the pulse signal is output, and a plurality of predetermined pulses being output after the pulses are output from the pulse generating means. A second counter for counting the number of clock signals output from the clock signal generator.
A measuring means, and a measurement value corresponding to one cycle of the pulse measured by the first measuring means is used for control necessary to follow a rapid change in the rotation speed of the internal combustion engine, and the second measuring means Measurement values corresponding to a plurality of cycles of the pulse measured in the above are selected in accordance with the control content so as to be used for control requiring a high-precision rotation speed of the internal combustion engine, and a measurement value suitable for the control content is selected. A rotation speed measuring device for an internal combustion engine, comprising: a selection unit.