JPS5814012A - Device for detecting rotary angle of distributor - Google Patents

Abstract

PURPOSE:To detect the angle highly accurately by a simple constitution, by providing angle detecting slits, long slits corresponding to the number of cylinders, reference position slits for a specified cylinder, and the like in a rotary disk which is synchronized with an engine. CONSTITUTION:The rotary disk 8 is formed on the shaft of the distributor which is rotated in synchronization with the engine as a unitary body. In said rotary disk 8, the detecting slits 8a... which are arranged at an equal angular interval on the same circumference, the slits 8b... which are arranged at an equal angular interval in correspondence with the number of the cylinders and longer than the slits 8a, a plurality of slits 8b which are in common with said slits 8b and used as the reference position for the specified cylinder, and the like are provided. By a pair of photoelectric pickups, the different types of the slits are detected, and the rotary angle for controlling fuel injection is determined. Therefore, in the simple constitution wherein only one pair of the photoelectric pickups are used, the rotary angle detecting device for the distributor which can detect the angle highly accurately is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a rotation angle detection device for a power distributor for an automobile engine.

The ignition timing of an internal combustion engine has a large effect not only on engine drivability, but also on the exhaust gas composition and fuel consumption rate, so in order to set it to the optimum value, the crankshaft, which rotates in synchronization with the engine, is required. It is necessary to accurately detect the rotational speed of the power distributor, and to control the ignition timing using a centrifugal advance mechanism and a negative pressure advance mechanism installed in the power distributor.

However, since the conventional advance angle mechanism is based on a mechanical control system, its accuracy and responsiveness are insufficient. Recently, improved control systems using electronic circuits have been attempted. In the case of electronic control, calculations are made by inputting data from various detection devices, and one of the data is the rotation angle of the power distributor, which is detected and supplied to the control circuit.

As an example of this rotation angle detection device, the following method is used. That is, a disc is rotated in synchronization with the crankshaft, and changes in the magnetic flux of a magnetic pickup facing a protrusion provided in the circumferential direction of this disc are extracted as an alternating voltage.
This is a method to obtain a predetermined pulse signal. However, since this method directly detects the rotation angle of the crankshaft, it requires a considerable amount of installation space in an appropriate location. Further, there is a problem in that malfunctions are likely to occur due to the influence of an external magnetic field, for example, changes in magnetic flux due to large current flowing through a starting motor at the time of starting, and leakage magnetic flux from a generator or an electromagnetic clutch for a car cooler.

In order to overcome these drawbacks, attempts have been made to incorporate a photoelectric pickup into a rotating plate that rotates in synchronization with the crankshaft to extract a predetermined pulse signal.

Conventional pulse signals pass through, for example, slits for angular position signals that divide the circumference of the rotating plate into 360 equal parts, and slits for reference position signals that are proportional to the number of cylinders and formed inside the slits for angular position signals. Since we need to detect light,
It is necessary to install multiple photoelectric pickups in the power distribution device. Therefore, it is difficult to find a place to install multiple Kouno pickups in a narrow space within a power distribution device, and the assembly process is difficult and costly.

On the other hand, fuel injection control may be performed with high precision using a signal that detects, for example, the position of the first cylinder of the engine. The above reference position signal is generated 21 times per crankshaft rotation (every 180 degrees) if the number of engine cylinders is 4, and one of these is used as a signal to detect the position of the first position. If it can be used as a device, it has the advantage of not requiring a special detection device, but this has not been used in power distributors that have been attempted in the past.

As mentioned above, the angular position signal and the reference position signal have conventionally been extracted using a plurality of photoelectric pickups, which has complicated the interior of the power distributor and increased costs. Furthermore, since a detection signal for the first cylinder position cannot be obtained, the fuel injection timing is insufficiently set.

An object of the present invention is to provide a rotation angle detection device for a power distributor that is capable of highly accurate detection with a relatively simple and inexpensive configuration.
Its features include a first group of slits for rotation angle detection that are provided on the rotary plate at small angular pitches on the same circumference, and a first group of slits that are arranged at equal angular intervals corresponding to the number of engine cylinders. A second slit group is provided on the same circumference and has the same gap and is vertically elongated for detecting cylinders, and this second slit group has the same gap and length and is a slit group for detecting a reference position corresponding to a specific cylinder. A third slit group is formed, and the light passing through each slit group is detected by one set of photoelectric pickups.

FIG. 1 is a screen diagram of the main parts of a power distributor that is an embodiment of the present invention. A shaft 1 that rotates at half the engine speed is installed at the center of a nohesing 2 via a bearing 3, and a collar 4 is fixed to its tip.

The rotary plate 8 and the flange portion 6a of the collar 6 are placed on the flange portion 4a of the collar 4, and the rotary plate 8 is held between the pins 5.
A spring washer is interposed at the bottom of the center hole of the collar 6, and the collar 6 is fixed to the shaft 1 with a screw 9. Further, an insulating plate 7 is fitted into the upper end of the collar 6 and fixed integrally therewith.

The stepped portion 1a of the shaft 10 locks the collar 4,
A base 10 is installed on the outer periphery of the shaft 1. The ball bearing 3 etc. is accommodated and the screw 14a is attached to the 9-1 housing 2.
It is fixed using. Further, a connector 11 is attached to the right side of the base 10 and connected to a power source. A circumferential protrusion is provided on the upper surface of the housing 2 to engage a synthetic resin cap 19, and a screw 14b is inserted into the female threaded portion of the housing 2 through a bushing 20 embedded therein to prevent removal. They are screwed together to form a power distribution device. Note that (d) a shield plate 15 is attached to the upper surface of the housing 2 to surround the lower end of the insulating plate 7 and cover the accommodation chamber of the rotary plate 8.

An annular printed board 12 is fixed on a base 10 in the housing 2, an electronic circuit is provided on the printed board 12, and photoelectric pickups 13 are installed above and below a rotary plate 8 on the left side thereof. This photoelectric pickup 13 has a light emitting element and a light receiving element facing each other, and detects light passing through a slit provided at the periphery of the rotary plate 8.

Further, the center electrode 1B of the cap 19 is in contact with the power distribution electrode 17 of the insulating plate 7, and the end of the power distribution electrode 17 is connected to the side electrode 16.
are closely facing.

FIG. 2 is a plan view of the rotating plate of FIG. 1. A large number of relatively short slits 8a for detecting the angular position are provided near the periphery, and slits 8b for detecting the reference position signal, which are approximately three times as long as the slits 8a, are provided every 90 degrees. It is being Furthermore, two sulins 8b are arranged at equal intervals in one place. The angle θ between these adjacent slits
Since 2 corresponds to 1 degree, the long and short slits 8
It is fractionated into 60 fractions. Note that the hole 8d provided at the center of the rotary plate 8 is a fitting hole for the collar 4, and a pair of pin holes 8C near it are holes through which the pin 5 shown in FIG. 1 passes.

Figure 3 is an explanatory diagram of the photoelectric pickup in Figure 1.
The same parts as in FIG. 1 are given the same reference numerals. 21 is a light emitting element, 22 is a light receiving element, two fixed slit plates 23 are installed between them, and the rotary plate 8 is rotated between these fixed slit plates 23. In other words, the light from the light emitting element 21 approaches the fixed slit plate 23)
23a, the slit 2 of the other slit plate 23
3b and is detected by the light receiving element 22, but the required signal is obtained only when the short slit 8a and the long slit 8b of the rotary plate 8 pass.

FIG. 4 is a plan view of the self-propelled slit plate of FIG. 3. Slits 23a and 23b are provided which are longer than the slits ga and 8b of the rotating plate 8 shown in FIG. The width of the slit 23b is T1, the length is A1, the width of the slit 23a is T2, and the length A is twice that of A.
The angle formed by the slit 23b and the slit 23b is assumed to be 10.

FIG. 5 is a circuit diagram provided on the printed board of FIG. 1. VCC is a power supply, R1-R18 are resistors, and C1-C6 are capacitors. The photoelectric pickup 13 is a light emitting element 2
1 and a light receiving element 22, the light emitting element 21 uses, for example, an infrared light emitting diode, and the light receiving element 22 uses, for example, a photodiode. When the light receiving element 22 is sensitive to light, if a reverse bias is applied to the cathode due to the photovoltaic force between the anode and the cathode, a current flows through the resistor R2.
A voltage is generated across it. 24.25 is a differential amplifier fi, and 26.27 is a comparator. Note that 28 is a transistor.

FIG. 6 is a time chart of the circuit shown in FIG.

A forward current flows from the power supply VCC to the light emitting element 21 via the resistor R1, and when the light receiving element 22 facing this receives light, a photocurrent flows. 8a, 8b of the rotating plate 8 and the slit 23a of the fixed slit 23.

23b repeats facing and non-facing, the light receiving element 22 receives a change in brightness and a voltage change occurs at both ends of the resistor R2.
This is amplified by the differential amplifier 24.

This is shown in FIG. 6 as the output at point a. The amplified voltage change is taken out by AC coupling between capacitor C1 and resistor R7, and resistors R6 and R7 are connected to the power supply voltage V C
A voltage change is obtained at point a with reference to the potential Vig obtained by dividing c.

The voltage v due to the change in brightness due to the angular position signal Surin) 8a
In addition to obtaining a change of 1, a voltage 2 is obtained due to the brightness change by the reference position signal Surin) 8b.

As shown in FIGS. 2 and 4, the slit 8b for the reference position signal is long and thin, and the amount of light received when the fixed slit 23a and the rotating slit 8a match is higher than when the other slits match. becomes large.

Therefore, the output current of the light receiving element 22 increases and the voltage change at point a becomes constant.

Next, a method of detecting the angular position signal 29 will be explained.

The potential at point b in FIG. 5 is adjusted to be the same potential as point a by resistor R8, resistor R9, and RIO.
The potentials at points and points b are applied to the positive and negative input terminals of the comparator 26, and a resistor R12 is inserted between the comparator 26 and the power supply VCC. The resistors R and 11 are used to give the input signal a hysteresis characteristic to prevent chattering of the output signal.

As shown in FIG. 6, as tm at point a changes, the angular position signal 29 is taken out as a change between 1" and 0" using the positive input voltage Vnw of the comparator 26 as a reference.

The reference position signal is applied to the positive input of the -C differential amplifier 25 via the resistor R13, and also to the capacitor 03.
It is inserted between this positive input and ground. Therefore, by forming a kind of integrating circuit with the resistor R13 and the capacitor C3, and setting the time constant appropriately, the voltage is smoothed and the potential VR can be obtained. That is, this potential vR is approximately equal to the value obtained by dividing the peak (1) of the waveform portion for detecting the angular position signal into two.

Potential VR is given to the positive input of the differential amplifier 25, and a value obtained by dividing the output potential by resistors R14 and R15 (11) is given as the negative input, so a potential v1 which is a predetermined times the potential VR is outputted. can get. This output V.

is higher than the peak V1 of the waveform portion for the angular position signal, and higher than the peak v2 of the waveform portion for the reference position detection signal I! !
l:<setting.

By applying the above output (1) to the positive input of the comparator 27 at the subsequent stage and applying the voltage change at point a to the negative input, the peak (2) of the reference position detection signal waveform can be detected.

As shown in Figure 2, there are 3 cylinders in the position corresponding to the first cylinder.
Since the slits 8b are successively provided, three reference position signals are successively extracted from this portion only. This output is inverted by a transistor 28 to obtain a reference position signal pulse 30. The number of pulses of the angular position signal 29 existing in the section from the first rising edge of the first cylinder signal to the last rising edge 11) is different from that of the other reference position signal 30 by '1''.
Since the number of pulses is greater than the number of pulses of the angular position signal 29 in the interval, it is easy to extract only the reference position signal of the first cylinder.

(12) The rotational speed detection device of this embodiment uses a photoelectric pickup using one light-emitting element and one light-receiving element in the power distribution device to detect the reference position signal and the angular position signal. At the same time, one of the reference position signals can be used as the first cylinder detection signal 9, and the accuracy of detecting the crank angle can be greatly improved. Furthermore, although a plurality of sets of photoelectric pickups have conventionally been used, in this embodiment, one set is sufficient, resulting in effects such as lower cost and shorter assembly time.

In the above embodiment, the reference position signal for detecting the first cylinder position is generated three times in succession, but this number is not limited to three, and the same effect can be obtained by providing a plurality of signals. It will be done.

The rotation angle detection device for a power distributor of the present invention can reduce the number of conventional photoelectric pickups to one set of photoelectric pickups, and can provide a simple, inexpensive, and high-precision rotation angle detection device. It has this effect.

[Brief explanation of drawings]

(13), . FIG. 1 is a cross-sectional view of the main parts of a power distributor that is an embodiment of the present invention.
Fig. 2 is a plan view of the rotary plate shown in Fig. 1, Fig. 3 is an explanatory diagram of the photoelectric pickup shown in Fig. 1, Fig. 4 is a plan view of the fixed slit plate shown in Fig. 3, and Fig. 5 is a plan view of the rotating plate shown in Fig. 1. The circuit diagram provided on the printed board shown in the figure, and FIG. 6 is a time chart of the circuit shown in FIG. 1... Shaft, 2... Housing, 3... Pair link, 4.6... Collar, 5... Pin, 7...
Insulating plate, 8... Rotation L9, 14... Screw, 10...
・Base, 1 construction... Connector, 12... Printed board, 13... Photoelectric pickup, 15... Shield plate, 16... Side electrode, 17... Distribution electrode, 18...
... center electrode, 19 ... cap, 20 ... bushing, 21 ... light emitting element, 22 ... light receiving element, 23 ...
・Fixed slit plate, 24.25 ・Differential amplifier, 2
6.27...Comparator, 28...Transistor, 29
...Angle position signal, 30...Reference position signal. Agent Patent attorney Hiroo Nagasaki' (1 other person) (14) 10th Condolence 40

Claims (1)

[Claims] 1. A photoelectric pickup that detects changes in the amount of light passing through a rotary plate that is integrated with the shaft of a power distributor that rotates in synchronization with the output shaft of the engine, and a slit provided in the rotary plate. , an electronic circuit for processing the output signal of the photoelectric pickup, and a printed board on which the electronic circuit is installed, and a combination of the photoelectric pickup and the printed board is set on a synthetic resin base. In the rotation angle detection device for a power distribution device mounted on the bottom of the housing, the rotating plate has a first group of rotation angle detection slits provided on the same circumference at small angular pitches, and a group of slits corresponding to the number of engine cylinders. The first slit group is provided at equal angular intervals on the same circumference as the first slit group, and the second slit group for cylinder detection, which is vertically elongated, has the same gap and length. and a third slit group for detecting a reference position corresponding to a specific cylinder, and a set of the photoelectric pickups detects light passing through each of the slit groups. rotation angle detection device. 2. The photoelectric pickup is a photointerrupter that detects light passing through each slit group of the rotating plate rotating between two fixed slit plates installed between the light emitting element and the light receiving element (-1). A rotation angle detection device for a power distributor according to claim 1.