JPH0658102B2 - Internal combustion engine rotation angle detection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation angle detection device for an internal combustion engine, and more particularly to a device for detecting a rotation angle of a pump shaft of a fuel pressure pump by a rotor and a transmitter. It is used to detect

2. Description of the Related Art There are various types of internal combustion engine rotation speed detection devices. In an internal combustion engine that uses a fuel injection pump, the rotation speed detection device is used as the fuel injection pump becomes electronically controlled. A rotation speed detection device of a type that is integrated with the above, that is, a type that detects the rotation speed of the pump shaft of a fuel injection pump driven by the crank shaft of an internal combustion engine has been widely used (for example, the actual development number 51). -3106
6). As such a rotational speed detection device for an internal combustion engine, for example, an electromagnetic pickup coil 1 having a configuration shown in FIG.
And a gear (pulsar) 3 are combined. FIG. 1 is a sectional view in a direction perpendicular to the axis of the fuel injection pump 4,
The gear (pulsar) 3 is attached to the pump shaft 5 that makes one revolution for every two revolutions of the crankshaft, and the electromagnetic pickup coil 1 installed opposite to the gear 3 is shown in FIG. 2B by the rotation of the gear 3. The voltage signal Vp as shown is generated. Since the cycle of the voltage signal Vp corresponds to the rotation speed of the internal combustion engine, the detection of the voltage signal Vp means that the rotation speed of the internal combustion engine is detected, and the waveform is obtained at the reference level Vs. Shaped, Figure 2C
If a rectangular wave such as the above is used and the period of the voltage signal Vp is measured by a known method, the rotational speed of the internal combustion engine can be obtained.

However, the internal combustion engine rotation speed detection device configured as described above has the following problems because the rotation speed of the internal combustion engine is detected using the rotation speed of the pump shaft. That is, when the pressurization of the fuel is started in the fuel pressure pump driven by the pump shaft (the timing is shown in FIG. 2A), the pump reaction force causes the pump shaft to twist and Since the rotational angular velocity changes, the voltage signal Vp generated in the electromagnetic pickup coil 1
2B is disturbed as indicated by a portion in FIG. 2B, and the revolution speed of the internal combustion engine converted from the pulse width (cycle) of the signal C whose waveform is shaped becomes an abnormal value. In FIG. 2, D indicates the rotation speed of the internal combustion engine converted from the pulse width τ0 of the signal B.

To solve this problem, for example, a measure such as increasing the level of the reference voltage Vs for waveform shaping with respect to the output voltage Vp of the electromagnetic pickup coil 1 can be considered, but if the rotation speed of the internal combustion engine changes, the electromagnetic pickup coil 1 Since the amplitude of the voltage signal Vp generated at the same time also changes, if the rotational speed of the internal combustion engine is to be accurately detected when it changes, the reference level must be changed accordingly. In addition to being complicated, it is difficult to obtain sufficient accuracy because the ability to follow changes in the rotational speed of the internal combustion engine deteriorates. That is, in order to accurately detect the rotational speed of the internal combustion engine with a simple configuration, the reference level Vs needs to be set at the center of the amplitude of the signal (generally at 0 volt).

Further, such a problem does not occur only in the rotation speed detection device of the internal combustion engine by the combination of the gear electromagnetic pickup coils given as an example, and basically, the rotation speed of the internal combustion engine is detected by the pump shaft receiving the injection reaction force. It is common to the rotational speed detection devices for internal combustion engines of this type.

[Object of the Invention] The present invention has been made in view of the above points, and an object of the present invention is to accurately determine the rotation angle of an internal combustion engine even when the rotational angular velocity of the pump shaft changes due to the pumping reaction force of the fuel pressure pump. An object of the present invention is to provide a rotation angle detection device for an internal combustion engine that can detect the above.

[Structure of Invention]

In order to achieve the above-mentioned object, the present invention is characterized in that a characteristic portion is formed for each predetermined angle, and a rotor that rotates in response to rotation of a pump shaft of a fuel pressure pump, and a rotor that is provided so as to face the rotor and that rotates the rotor. An oscillator that sequentially detects the characteristic portions that move in accordance with, and generates an electric signal whose signal level changes each time the characteristic portions are detected; and a signal level of the electric signal from the transmitter is a predetermined reference. And a waveform shaping means for outputting a rectangular wave signal corresponding to the electric signal, the signal level of the electric signal from the transmitter being the reference level. The mounting position of the rotor or the transmitter with respect to the pump shaft is set so that the fuel pressure pump is in a pressure stroke at a time when the level is far from the value. Adopt the technical means of the angular detector.

[Action]

In the present invention configured as described above, the pump shaft of the fuel pressure pump is rotationally driven by the internal combustion engine, and the rotor is rotated.
Then, the signal level of the electric signal from the oscillator changes in accordance with the movement of the characteristic portion accompanying the rotation of the rotor. Then, the waveform shaping means detects the intersection of this electric signal and a predetermined reference value and outputs a rectangular wave. Here, the rotation fluctuation of the rotor that occurs when the fuel pressure pump is in the pressure stroke appears as noise in the signal level of the electric signal from the oscillator, but in the present invention, the output level of the electric signal from the oscillator is waveform shaped. Since the mounting position of the rotor or the transmitter with respect to the pump shaft is set so that the fuel injection pump is in the pressure stroke at the time when the level is far from the reference value of the means, noise generated when the fuel injection pump is in the pressure stroke is This occurs at a time distant from the intersection determination timing in the waveform shaping means, and the influence on the determination in the waveform shaping means is reduced. Therefore, in the rectangular wave output from the waveform shaping means, the error due to the rotation fluctuation of the fuel pressure pump is reduced,
The exact rotation angle is detected.

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 3 is a partial cross-sectional view showing a schematic structure of a well-known row-type fuel injection pump which is used in the internal combustion engine rotation speed detection apparatus according to the embodiment of the present invention, and FIG. 4 is a cross-section taken along the line AA 'in FIG. It is a figure.

In the figure, 10 is a column-type fuel injection pump for injecting fuel into a 6-cylinder engine (not shown), 13 is a pump shaft of the fuel injection pump, and 15 is a rotor fitted in the pump shaft 13 by a key 18 and having 12 teeth. A pulsar, 20 is an electromagnetic pickup coil that detects a pulse corresponding to the number of teeth of the pulsar 15 per revolution of the pump shaft 13, and 22 is the pulsar 15 screwed into a screw portion provided at the end of the pump shaft. A round nut fixed to 13 and a waveform shaping circuit 24 for shaping the signal detected by the electromagnetic pickup coil 20 are shown. Further, 33 is a control rack for changing the pressurizing time (fuel injection amount) of the pressurizing pump (driven by the pump shaft 13) provided for each cylinder in the column-type fuel injection pump 10, and 34 is movable. A rack position detector that detects the position of the control rack 33 that is controlled by the iron core type linear solenoid 35, and 36 indicates oil that serves as lubricating oil for the pump shaft and the like, respectively. Completion of fuel injection to each cylinder performed by the row-type fuel injection pump 10 is controlled by a control circuit (not shown).
It is determined according to the operating state of the engine. The control circuit reads the signal from the rack position detector 34,
The movable iron core type linear solenoid 35 is driven, the position of the control rack 33 is controlled, and the well-known fuel injection amount control for realizing the fuel injection with the required fuel amount for each cylinder is performed.

The pulsar 15 is made of a magnetic material, for example, ferrite, and the twelve protrusions 15a are configured to pass near the detection end 20a of the electromagnetic pickup coil 20 by the rotation of the pump shaft 13. The pump shaft 13 has a fuel injection pressure of several hundred kg / c in the row type fuel spray pump 10.
It drives a fuel injection pump that pressurizes at an injection pressure of m ² or more, and receives an injection reaction force at the start and end of pressurization. The reaction force works to decrease the rotation angle of the pump shaft at the start of pressurization and increase it at the end of pressurization.

In the present embodiment, the pulsar 15 and the pump shaft 13 are such that one of the protrusions 15a of the pulsar 15 is just the electromagnetic pickup coil 20 when pressurization starts in the fuel pressure pump.
The position of the key groove of the pulsar 15 with respect to the key groove of the pump shaft 13 is determined so as to come close to the position where the highest voltage is generated, and the key 18 is used to fix the positional relationship. That is, when the cam (not shown) attached to the cam shaft 13 is in one of the positions where the plunger (not shown) is at the bottom dead center in the fuel pressure pump, the corresponding position of the pump shaft 13 is uniquely designed. Since the position of the pulsar 15 is fixed, the pulsar 15 is positioned so that the edge of the protrusion 15A of the pulsar 15 just passes over the detection end 20a of the electromagnetic pickup coil 20 at the position of the cam shaft 13 (corresponding to the position where the pressurization starts). It will be fixed to the pump shaft 13. When the edge of the protruding portion 15a of the pulsar 15 crosses over the detection end 20a of the electromagnetic pickup coil 20a, the change in the magnetic flux density in the magnetic field formed by the electromagnetic pickup coil 20 becomes almost maximum, so that the electromagnetic pickup coil 20 is generated. The power is almost maximum. Since the start of pressurization of the fuel pressure pump, that is, the fuel injection start timing is slightly changed depending on the operating state of the engine, the pump shaft is adjusted so that the highest voltage is generated in the electromagnetic pickup coil 20 completely in synchronization with the start of pressurization. Although the positions of the pulsar 13 and the pulsar 15 cannot be fixed, if the position of the pulsar 15 is optimally fixed with respect to the pump shaft 13 in synchronization with the fuel injection start timing at the time of steady operation in medium / high speed. It is possible to make one of the protrusions 15a of the pulser 15 just near the position where the highest voltage is generated in the electromagnetic pickup coil 20 when the pressurization starts in the fuel pressure pump over the entire operating state.

Next, the principle of pulse signal detection by the electromagnetic pickup coil 20 and the protrusion 15a of the pulsar 15
This will be described with reference to FIGS. FIG. 5 is a schematic configuration diagram of an electric system of the electromagnetic pickup coil 20 and the waveform shaping circuit 24. As shown, the electromagnetic pickup coil 20
Has a structure in which a coil is wound around a magnetized iron core 20a, and a magnetic flux penetrating the iron core 20a is led out from one end face of the iron core 20a to the outside to form a magnetic field returning to one end face. There is. When the protrusion 15a of the pulsar 15 made of a magnetic material crosses this magnetic field, the magnetic flux density changes, and an electromotive force is generated in the coil so as to prevent the change in the magnetic flux density. The electromotive force captured as the voltage Va at point a in FIG. 5 is shown as A in FIG.

The waveform shaping circuit 24 is a circuit centered on a well-known comparator 24a that operates by receiving the supply of the power supply voltage Vcc, and when the voltage Va input to the circuit is 0 volt or less, its output, that is, at the point b. The voltage Vb is configured to have a high level, as indicated by B in FIG. The waveform shaping circuit 24 shown in FIG. 5 is provided with resistors, capacitors, zener diodes, etc., which are represented by normal symbols, for the purpose of protection against noise and overvoltage input.

As shown by B in FIG. 6, if the pulse interval (ti) of the output signal of the waveform shaping circuit 24 is counted and accurately measured by an external timer (not shown), the rotational angular velocity of the pulsar 15 can be known. Therefore, the rotational speed of the pump shaft, that is, the rotational speed of the crankshaft of the internal combustion engine connected to the pump shaft can be detected.

In the present embodiment configured as described above, when the electromotive force generated in the electromagnetic pickup coil 20 due to the rotation of the pulsar 15 caused by the rotation of the pump shaft 13 becomes close to the peak value, the pressurization of the fuel pressure pump is started. It is configured to be. Therefore, the output of the electromagnetic pickup coil 20 at the timing when the pump shaft 13 receives the injection reaction force is not near the reference level Vs (here, 0 volt) of the waveform shaping circuit 24, and the erroneous pulse interval is caused by the disturbance of the waveform. Will never produce the output of. That is, the seventh
As shown in FIG. A, the pump shaft 13 receives a total of six injection reaction forces for each fuel injection in each cylinder from the fuel start timing P of the first cylinder to one cycle of the engine.
Even if the rotational angular velocity changes due to the injection reaction force, the output voltage level of the electromagnetic pickup coil 20 at that time is a high level as shown in FIG. b, the reference voltage Vs
The signal after waveform shaping using is as shown in FIG. 7C, and no error occurs in the pulse interval ti.

Therefore, by using the internal combustion engine rotation speed detection device configured as described above, the rotation speed of the engine is not affected by the injection reaction force from the rotational angular velocity of the pump shaft 13 of the fuel injection pump 10 with a simple configuration. You can measure the number accurately.

In the present embodiment, the pump shaft 13 that drives the cam
The relationship between the position and the phase of the output voltage is determined by setting the mounting position of the pulser 15 on the pump shaft 13, but the mounting position of the electromagnetic pickup coil 20 can be varied along the circumference of the pulser 15. If the structure is adopted, the electromagnetic pickup coil 20 is arranged with respect to the position of the pump shaft 13.
It does not matter at all to determine the mounting position of. Since the pulsar 15 is housed in the main body of the fuel injection pump 10, it is generally impossible to adjust the mounting position after assembly, but if the mounting position of the electromagnetic pickup coil 20 is adjusted, the position of the pump shaft 13 can be relatively easily adjusted. This is preferable because the phase of the output voltage of the electromagnetic pickup coil 20 can be adjusted with respect to.

Further, in this embodiment, the positional relationship between the pump shaft 13 and the pulsar 15 is determined so that the output voltage of the electromagnetic pickup coil 20 is disturbed by the injection reaction force in the vicinity of the positive peak value of the output voltage. , The disturbance of the output voltage occurs near the negative peak value of the output voltage, that is,
When a pulsar having 12 teeth is used as in the present embodiment, the pulsar 15 may be attached at a position displaced by about 15 ° from the position with respect to the pump shaft 13 of the present embodiment. Also, pump shaft 1
The position of the pulsar 15 with respect to 3 does not necessarily have to be adjusted to a position where the output voltage of the electromagnetic pickup coil 20 has a peak value. That is, the pump shaft 1 by the injection reaction force
It is sufficient that the disturbance caused by the change in the rotational angular velocity of 3 in the output voltage of the electromagnetic pickup coil 20 occurs at a level with a sufficient margin with respect to the reference level Vs of the waveform shaping circuit 24, including the peak value. The position of the pulsar 15 with respect to the pump shaft 13 may be determined so that the output voltage of the electromagnetic pickup coil 20 is disturbed by the injection reaction force within a predetermined range or outside a predetermined range including the reference level. As described above, in the fuel injection pump of the type that adjusts the fuel injection start timing, it may be difficult to always adjust the output of the electromagnetic pickup coil 20 to the peak just at the fuel injection start timing. The positioning as described above has an advantage that a wide margin can be secured in adjusting the device.

Further, in the present embodiment, the pump shaft 13 and the pulsar 15 have the key groove and are fixed by the key 18. However, a method of fixing the pump shaft 13 and the pulsar 15 by using a plurality of grooves in which the shaft circumference is equally divided ( 8
Other methods such as (Fig.) And screwing can be used. It is often preferable to use such a configuration that the positions of the pump shaft 13 and the pulsar 15 can be adjusted in the sense that an error in connecting the crank shaft of the engine and the pump shaft can be adjusted.

Further, in this embodiment, as the rotor of the present invention, the pulsar 15 having the protrusion as the characteristic portion is used. Further, in this embodiment, as the transmitter of the present invention, the electromagnetic pickup coil 20 whose signal level changes in the positive and negative directions each time the protrusion of the rotor passes is used. In addition, ferrite is used as the pulser 15,
Although the shape has 12 protruding portions, the number of protruding portions may be any integral multiple of the number of injection cylinders, and the configuration is such that the magnetic field formed by the electromagnetic pickup coil 20 varies depending on the rotation of the pump shaft 13. Any material can be used as long as it has alternating magnetic permeability portions, as shown in FIG. 9 (A).
As shown in FIG. 9, the magnetic material 101 may be embedded in the disk-shaped non-magnetic material 100, or as shown in FIG.
It may be configured such that a magnetic body (for example, a magnetic tape) 111 magnetized to have poles or N poles is attached. In addition, a hall element or the like is used as the electromagnetic pickup coil 20, and further, the outer peripheral portion of the rotor is a reflecting surface having alternating optical differences, and the transmitter optically detects this. The pulsar 15 having the same shape as the pulsar 15 in the example may be configured to optically detect the passage of the protruding portion 15a by blocking the transmitted light by the protruding portion 15a. An optimum method may be used according to the mode of the fuel injection pump in which the engine speed detection device is used.

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and it is needless to say that the present invention can be implemented in various modes without departing from the scope of the present invention.

[Advantages of the Invention] As described above, according to the present invention, a rotational fluctuation may occur due to the pressurizing reaction force of the fuel pressure pump, and this rotational fluctuation may cause noise to be mixed in the electric signal from the transmitter. Even if the output level of the electric signal from the transmitter becomes a level away from the reference value of the waveform shaping means, the roke or the mounting position of the transmitter with respect to the pump shaft is set so that the fuel injection pump enters the pressure stroke. Therefore, the noise generated when the fuel pump is in the pumping stroke is generated at a time distant from the crossing determination time in the waveform shaping means, and the influence on the determination in the waveform shaping means is reduced. For this reason,
With the rectangular wave output from the waveform shaping means, the error due to the rotation fluctuation of the fuel pressure pump is reduced, and the accurate rotation angle can be detected.

[Brief description of drawings]

FIG. 1 is a transverse cross-sectional view of a pump shaft showing a schematic configuration of a conventional internal combustion engine rotation speed detecting device, FIG. 2 is an explanatory view similarly showing how the rotation speed is detected, and FIG. 3 is a row of an embodiment of the present invention. Type fuel injection pump partially sectional view, FIG. 4 is an AA ′ sectional view of FIG. 3, FIG. 5 is a schematic configuration diagram of an electric system of the electromagnetic pickup coil 20 and the waveform shaping circuit 24, and FIG. Is an explanatory diagram showing input / output signals of the waveform shaping circuit 24, FIG. 7 is an explanatory diagram showing a state of rotation speed detection in the embodiment, and FIG. 8 is a pulser 1.
5 is a perspective view showing an example of a method for fixing 5 to the pump shaft 13;
9A and 9B are plan views showing other shapes and configurations of the rotor. 10 ... Fuel injection pump 13 ... Pump shaft 15 ... Pulser 15a ... Projection 18 ... Key 20 ... Electromagnetic pickup coil 24 ... Waveform shaping circuit

Claims (3)

[Claims] 1. A rotor having a characteristic portion formed for each predetermined angle and rotating in response to rotation of a pump shaft of a fuel injection pump; and a rotor provided facing the rotor, wherein the rotor moves with the rotation of the rotor. A transmitter that sequentially detects the parts and generates an electric signal whose signal level changes each time the characteristic part is detected; and a signal level of the electric signal from the transmitter that crosses a predetermined reference value. And a waveform shaping means for outputting a rectangular wave signal corresponding to the electric signal, wherein the signal level of the electric signal from the transmitter is different from the reference value. A rotation angle detecting device for an internal combustion engine, wherein a mounting position of the rotor or the transmitter with respect to the pump shaft is set so that the fuel injection pump is in a pressure stroke at a certain time. 2. The waveform shaping means determines an intersection between a signal level of the electric signal and a reference value which is set substantially at the center of the change width of the signal level of the electric signal from the oscillator,
The rotation angle detection device for an internal combustion engine according to claim 1, wherein a rectangular wave signal corresponding to the electric signal is output. 3. The mounting position of the rotor or the transmitter with respect to the pump shaft is set so that the fuel injection pump is in the pressure-feeding stroke when the output level of the electric signal from the transmitter reaches a substantially peak value. The rotation angle detection device for an internal combustion engine according to claim 2, wherein