JP2007278875A - Encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encoder capable of precisely detecting an absolute angle of a rotating body. <P>SOLUTION: A magnetic pole part 12 provided to a rotary shaft 10 includes a plurality of magnetic pole parts, wherein each magnetic pole part is constituted of either a first magnetic pole type having an area of an N-pole larger than that of a P-pole or a second magnetic pole type having an area of the an N-pole narrower than that of a P-pole. A combination of sequence trains of the first magnetic pole type and the second magnetic pole type is different in a first area and a second area along a circumference of the rotating body. The angle of the rotating body is determined on the basis of the combination of the sequence train. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an encoder that detects an angle and a rotational position of a rotating body.
In particular, the present invention relates to an encoder that determines an absolute angle and a rotational position of a rotating body.
The present invention also relates to an encoder suitable for a crank angle detection encoder, a cam angle encoder, and the like.

As an encoder, a crank angle detection encoder that detects the rotational position of the crankshaft of the vehicle will be described as an example.
The crank angle detection encoder controls the ignition timing and fuel injection timing of the internal combustion engine (engine), and is used for detecting the rotation angle of the crankshaft, detecting the rotation speed of the engine, detecting the rotation direction of the engine, and the like. Yes.
That is, in order to determine the ignition timing, fuel injection timing, and the like from the rotational position of the crankshaft, a crank angle detection encoder is used for detecting the top dead center (TDC) and detecting the rotational angle of the crankshaft. .

  When the engine is started, the engine rotation is unstable. For this reason, the ignition timing and the fuel injection timing may be shifted, leading to a reduction in fuel efficiency. For this purpose, early detection of the rotation angle of the crankshaft is desired.

  Patent Document 1 discloses an invention for early detection of a rotation angle at the time of engine start. However, there are points to be improved in the present invention, and various proposals have been made.

Patent Document 2 discloses a technique for discriminating a track zone by combining outputs of a plurality of encoders in which a sensor and a gear cutter are combined.
However, this technique has a problem that a structure is complicated because it is necessary to provide a large number of encoders configured by combining a sensor and a gear cutter. As a result, the price increases, it may be difficult to secure a place where a large number of encoders are provided, or the surrounding space may be adversely affected by the provision of a large number of encoders. Furthermore, if this technique is used, the burden of arithmetic processing is large.

Patent Document 3 relates to the technology of an encoder having a top dead center (TDC) starting portion, and the TDC starting portion has a signal output portion having a width two to three times the normal width, and the rotation is performed in this wide portion. The technique which shows a reference point and shows the position and rotation angle of a rotation angle direction in the other part is disclosed.
However, this technique has a disadvantage that it must pass through a wide part in order to detect the reference point. For example, it cannot be detected unless it is rotated by one rotation (360 degrees) at the maximum.

By the way, there are a method of providing a gear cutter and a method of providing a multipolar magnet on the rotating shaft for crank angle detection.
The method using a multipolar magnet has advantages such as no need for machining, miniaturization, high detection accuracy, and no deterioration due to wear.

Patent Document 4 discloses a technique for detecting the absolute angle of a rotating body by a combination of pitch intervals of multipolar magnets using metal.
However, in this technique, when a rubber magnet is used, the formation of an extremely wide magnetic pole leads to a decrease in magnetic force accuracy, and a problem that the practicality is low is assumed.

Japanese Patent No. 3395518 Japanese Patent Laid-Open No. 11-229948 JP 11-294217 A Japanese Unexamined Patent Publication No. 5-040004

Each of the above-described conventional techniques has a problem in detecting the absolute angle of the rotating body, and further, there are many matters to be improved in terms of detection accuracy and practicality.
In particular, there is a problem to be improved in terms of detecting an arbitrary angle of the rotating body, for example, early detection of the rotation angle at the time of starting the engine.

  In the above example, the encoder for detecting the crank angle is described as the encoder. However, the rotating body is not limited to the crankshaft, and it is desired to accurately detect the absolute angle of the cam angle encoder and other ordinary rotating bodies. Yes. In that case, there is a problem to be overcome similar to the above.

An object of the present invention is to provide an encoder capable of accurately detecting the absolute angle of a rotating body at an arbitrary position of the rotating body.
Another object of the present invention is to provide a low-cost encoder that is practical and easy to manufacture.
Furthermore, this invention is providing the encoder which can detect the rotational speed of a rotary body.

Another object of the present invention is to provide an encoder suitable for use as a crank angle detection encoder.
Another object of the present invention is to provide an encoder suitable for use as a cam angle encoder.

The encoder of the present invention is provided with a plurality of magnetic pole portions along the circumference of the rotating body.
Each magnetic pole portion is composed of a first magnetic pole (for example, N pole) and a second magnetic pole (for example, S pole), and the area of the first magnetic pole is wider than the area of the second magnetic pole (the occupation ratio is high). Either the first magnetic pole type or the second magnetic pole type in which the area of the first magnetic pole is narrower than the area of the second magnetic pole (occupation ratio is low) is configured.
Furthermore, the plurality of magnetic pole portions in arbitrary different regions along the circumference of the rotating body are configured so that the combinations of the order rows of the first magnetic pole type and the second magnetic pole type are different. That is, the magnetic pole portions are arranged over the rotating body so that the combination of the magnetic pole types of the plurality of magnetic pole portions in a certain region is different from the combination of the magnetic pole types of the plurality of magnetic pole portions in the other region. As a result, the absolute angle of the rotating body at that time can be uniquely determined from the combination of magnetization detection data of a plurality of magnetic pole types.
The certain area and the other area may partially overlap or may be completely separated from each other.
The magnetic detection sensor detects the magnetization state of the plurality of magnetic pole portions arranged on the rotating rotator, and outputs a time-series pulse signal corresponding to the rotation of the rotator.
The angle detection circuit outputs a corresponding angle signal defined based on the combination of the first magnetic pole type and the second magnetic pole type, which is output from the magnetic detection sensor.

The magnetic detection sensor and the plurality of magnetic pole portions may be in a relative positional relationship. For example, as described above, a plurality of magnetic pole portions may be disposed on the rotating body, and a magnetic detection sensor may be disposed on the fixed portion. Conversely, a magnetic detection sensor may be disposed on the rotating body. A plurality of magnetic pole portions may be disposed on the fixed portion.
Further, the magnetic pole part can be pre-manufactured with the magnets magnetized in the first and second magnetic pole types described above and fixed to the rotating body, or can be rotated. It is also possible to form a magnetization forming portion in the body with a magnetic material and magnetize the magnetization forming portion in the first and second magnetic pole types described above along the circumference of the rotating body.

In the present invention, the absolute angle of the rotating body can be uniquely determined with an accuracy that is an integral multiple of the angle occupied by one magnetic pole portion (the angle occupied by a plurality of magnetic pole portions that define a combination of the above-mentioned sequence). As a result, an arbitrary absolute angle of the rotating body can be detected early.
Moreover, according to this invention, the rotational speed of a rotary body can also be calculated | required using the said angle detection.

  The encoder of the present invention can be realized with a simple configuration. As a result, it is possible to provide a low-cost encoder that is practical, easy to manufacture.

Each magnetic pole portion includes a first magnetic pole type in which the region of the first magnetic pole (for example, N pole) is wider (the occupation ratio is higher) than the region of the second magnetic pole (for example, S pole), and the region of the first magnetic pole is first. Since it can be configured with any of the second magnetic pole types that are narrower than the area of the two magnetic poles (occupation ratio is low), and a certain area can be configured by appropriately combining a plurality of magnetic pole portions of the first magnetic pole type and the second magnetic pole type. Various combinations can be taken, and the angle discrimination is high.
Using high discrimination, the angular resolution can be increased. As a result, the accuracy can be improved and the angle can be detected at an early stage.

The encoder of the present invention is suitable for a crank angle detection encoder, a cam angle encoder, and the like.
For example, if this encoder is used as a crank angle detection encoder, the rotation angle of the engine can be detected quickly at an early timing when a predetermined magnetic pole portion rotates from the start of engine rotation.
The same applies to the cam angle detection encoder.

First Embodiment A crank angle detection encoder will be described as an embodiment of the encoder of the present invention.
A crank angle detection encoder according to a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a diagram showing a configuration of an encoder apparatus according to the present invention. FIG. 1A is a schematic configuration diagram of an encoder device. FIG. 1B is a cross-sectional view showing the positional relationship between the magnetic pole portion 12 provided on the rotating shaft 10 illustrated in FIG. 1A and the first and second magnetic detection sensors.
The rotating shaft 10 is, for example, a crankshaft of a vehicle and rotates according to the rotation of the engine.
The rotating shaft 10 is provided with a magnetic pole portion 12 along its circumference.
A first magnetic detection sensor (hereinafter referred to as a first detection sensor) 1 and a second magnetic detection sensor (hereinafter referred to as a second detection sensor) are brought close to the magnetic pole portion 12 so that the magnetization state of the magnetic pole portion 12 can be detected. 2 is arranged so that the magnetization of the magnetic pole portion 12 can be detected.
The angle detection circuit 100 uses the first sensor detection pulse PLS1 obtained from the detection signal S1 of the first sensor 1 and the second sensor detection pulse PLS2 obtained from the detection signal S2 of the second sensor 2 to Detect absolute angle. Details thereof will be described later.

Pole unit Figure 2 is a diagram illustrating a pattern and the determination result of the magnetic pole portion 12 that is illustrated in FIG.
FIG. 2A is a diagram illustrating the magnetic pole portion 12 shown in FIG.
In this example, 36 magnetic pole portions are provided on one circumference of the rotating shaft 10. Therefore, in this example, the resolution of one magnetic pole part is 10 degrees.
Each magnetic pole portion is composed of a pair of magnets, that is, a magnet having an N pole (first magnetic pole) and an S pole (second magnetic pole) facing the first detection sensor 1 and the second detection sensor 2. It is composed.
However, the occupation ratios of the N pole and S pole of each magnetic pole portion are different. As illustrated in FIG. 2A as “A” and “B”, and the details thereof are illustrated in FIG. 2C, two types of occupation ratios of the N pole and the S pole are set. The magnetic pole types are called A magnetic pole type and B magnetic pole type.
The A magnetic pole type corresponds to the second magnetic pole type of the present invention, and the B magnetic pole type corresponds to the first magnetic pole type of the present invention.

In the A magnetic pole type, the occupied area of the S pole in one magnetic pole part is wider than the occupied area of the N pole. Therefore, when the magnetization state of this magnetic pole part is detected by the first detection sensor 1 or the second detection sensor 2, the period for detecting the S pole is long and the period for detecting the N pole is short. Thus, the difference in the occupation ratio between the S pole and the N pole is a difference in the duty ratio of the signal detected by the first detection sensor 1 or the second detection sensor 2.
On the other hand, in the B magnetic pole type, the occupied area of the N pole in one magnetic pole part is wider than the occupied area of the S pole. Therefore, when the magnetization state of this magnetic pole part is detected by the first detection sensor 1 or the second detection sensor 2, the period for detecting the N pole is long and the period for detecting the S pole is short. As described above, the difference in the occupation ratio between the S pole and the N pole is the difference in the duty ratio of the signal detected by the first detection sensor 1 or the second detection sensor 2.

A method for forming the magnetic pole portion will be described.
In the first method, a magnetic pole portion having magnets magnetized in the above-described first and second magnetic pole types can be manufactured in advance and fixed to a rotating body.
As a second method, a magnetization forming portion is formed of a magnetic material on a rotating body, and the above-described first and second magnetic pole types are magnetized along the circumference of the rotating body on the magnetization forming portion. You can also.

An example of the occupation ratio will be described.
In the A magnetic pole type, for example, the occupation ratio of the N pole is 30 to 40% of one magnetic pole part, and the occupation ratio of the S pole is 70 to 60% of one magnetic pole part. On the other hand, in the B magnetic pole type, for example, the occupation ratio of the N pole is 60 to 70% of one magnetic pole part, and the occupation ratio of the S pole is 40 to 30% of one magnetic pole part.
The occupation ratio (duty ratio) between the N pole and the S pole in one magnetic pole can be arbitrarily determined as long as one is larger than the other. However, the separation interval (pitch) between the first magnetic detection sensor 1 and the second magnetic detection sensor 2, the rotation speed of the rotary shaft 10 that rotates at high speed, and the first magnetic detection sensor 1 and the second magnetism with respect to the rotary shaft 10. Considering the detection limit of the detection sensor 2 and the like, the determination is made with some tolerance.
Hereinafter, in this embodiment, the A magnetic pole type has an N pole occupation ratio of 40% of one magnetic pole part, the S pole occupation ratio of 60% of one magnetic pole part, and the B magnetic pole type has an N pole occupation ratio. The case where 60% of one magnetic pole part and the occupation ratio of the S pole are 40% of one magnetic pole part will be described as an example.

In the present embodiment, the combination of the A magnetic pole type and the B magnetic pole type magnetic pole parts and the order of the six consecutive magnetic pole parts are arranged so as not to have the same pattern throughout the entire circumference of the rotating body. Designing.
For example, the magnetic pole types of six magnetic pole portions and their order are exemplified below.

[Table 1]
(1) The range of 0 to 60 degrees, “AAAAAAA”
(2) Range of 10 to 70 degrees, “AAAAAAB”
(3) Range of 20-80 degrees, “AAAAABA”
(4) 30-90 degree range, “AAABAA”
(5) A range of 40 to 100 degrees, “AABAAA”
(6) A range of 50 to 110 degrees, “ABAAAA”
(7) 60-120 degree range, “BAAAAB”
(8) A range of 120 to 180 degrees, “BAAABA”
(9) 180-240 degree range, “BAAABB”
(10) Range of 240-300 degrees, “BAABAA”
(11) 300 to 360 degree range, “BBBBBBB”
(12) Range of 330 to 030 degrees, “BBBAAA”

As will be described later, in the angle detection circuit 100, from the detection signal S1 of the first sensor and the detection signal S2 of the second sensor, for example, the B magnetic pole type is logical 1 and the A magnetic pole type is logical 0. When determined, a time-series pulse signal as illustrated in FIG. 2B is obtained according to the rotation of the rotating body 10.
Describing the above example, for example, when six pulse trains of “0, 0, 0, 0, 0, 0” are obtained, it can be seen that the angle of the rotating shaft 10 is 60 degrees. Similarly, when six pulse trains “0, 0, 0, 0, 0, 1” are obtained, it can be seen that the angle of the rotating shaft 10 is 70 degrees.
As described above, an angle corresponding to the width of one magnetic pole part, in this example, a resolution of 10 degrees, which is the minimum angle, and an angle in a range occupied by a plurality of consecutive magnetic pole parts in this example. It can be detected uniquely. That is, when the magnetic pole type of the six continuous magnetic pole portions is detected, the angle of the rotating body 10 at that time can be detected.
This angle detection means that the absolute angle of the rotating body 10 can be uniquely (uniquely) made instantaneously.

In the present embodiment, the magnetic pole type in the region of 0 to 60 degrees and the magnetic pole type in the region of 300 to 360 degrees are distinguished so that the end of one rotation of the rotating shaft 10 is clearly distinguished from the beginning. “AAAAAAA” and “BBBBBBB” are set.
For example, when magnetized in this way, it is easy to determine the order sequence of the magnetic pole type when performing maintenance and inspection. Therefore, detection of the reference position of the rotating body 10, for example, the position of the top dead center, etc. Convenient to.

3A and 3E show the positional relationship between a part of the N pole and the S pole in the magnetic pole part when the A magnetic pole type magnetic pole part is detected by the first detection sensor 1 and the second detection sensor 2. FIG. 4 is a diagram showing the waveforms of magnetic flux change, first sensor detection pulse PLS1 and second sensor detection pulse PLS2.
FIGS. 3B and 3E show the positional relationship between some N poles and S poles in the magnetic pole part when the B magnetic pole type magnetic pole part is detected by the first detection sensor 1 and the second detection sensor 2. FIG. 4 is a diagram showing the waveforms of magnetic flux change, first sensor detection pulse PLS1 and second sensor detection pulse PLS2.
In the angle detection circuit 100, the first sensor detection pulse PLS1 and the second sensor detection pulse PLS2 are obtained by using the reference level REF as the zero cross position of the magnetic flux for the detection signal S1 of the first sensor and the detection signal S2 of the second sensor. The magnetic flux detection value above the level REF is illustrated as “high level”, and the magnetic flux detection value below the reference level REF is illustrated as “low level”.

The first detection sensor 1 and the second detection sensor 2 are, for example, arranged with a width p / 2 that is half of the width (pitch) p of one magnetic pole portion so as to detect the magnetization region (N pole, S pole). Yes. In addition, the space | interval of the 1st detection sensor 1 and the 2nd detection sensor 2 should just be arrange | positioned by the space | interval which can detect the wide magnetic pole area | region in each magnetic pole part.
Specifically, the first detection sensor 1 and the second detection sensor 2 theoretically have a first magnetic pole portion of the second magnetic pole type (A magnetic pole type in this example) having a width (pitch) p of one magnetic pole portion. It is wider than the width obtained by multiplying the occupancy ratio of N pole in this example, and the pitch p is multiplied by the occupancy ratio of the first magnetic pole part (N pole in this example) of the first magnetic pole type (B magnetic pole type in this example). It may be installed in a range narrower than the width. For example, when the occupation ratio of the N pole of the A magnetic pole type in this example is 40% of the width of one magnetic pole part and the occupation ratio of the N magnetic pole of the B magnetic pole type is 60% of the width of one magnetic pole part, the theoretical 2 The distance d between the two detection sensors 1 and 2 is [0.4p <(distance d between two sensors) <0.6p]. However, if the distance d between the two sensors approaches the theoretical critical value, it becomes easier to introduce an error in the determination based on the magnetic flux detection in the second detection sensor 2 positioned after the first detection sensor 1. The distance d is preferably about a width p / 2 ± 2% which is half the width (pitch) p of one magnetic pole part. In this example, the distance d between the two sensors is p / 2.
In the present invention, the distance d between the two sensors may be set to a value obtained by adding an arbitrary multiple of the sensor width p in one magnetic pole portion. Specifically, in the case of this example, [(0.4p + n × p) <(sensor interval d) <(0.6p + n × p), where n is an arbitrary integer less than the total number of magnetic pole portions. ]. In this case, since the two sensors 1 and 2 are not arranged within the width of one magnetic pole part, for example, even when the width of one magnetic pole part is narrower than the dimension of the sensor element, there is a restriction on the dimensions. In addition, the present invention can be implemented, and has an advantage that the magnetic pole portion is designed and the flexibility (degree of freedom) of the sensor element to be used is excellent.

The magnetic flux changes according to the rotation of the rotating shaft 10, but the change in the magnetic flux is shown in FIG. 3A. The level of the detection signal S1 of the first sensor goes from minus to plus (from low level to high level). On the other hand, when the reference level REF is exceeded (when 0 crossing is performed), it indicates that the detection signal S2 of the second sensor is below the reference level REF (low level).
On the other hand, in FIG. 3B, when the level of the detection signal S1 of the first sensor goes from minus to plus (from low level to high level) and exceeds the reference level REF (when zero crossing), The detection signal S2 of the two sensors also indicates a high level that exceeds the reference level REF.

In the present embodiment, the angle detection circuit 100 detects that the level of the detection signal S1 of the first sensor goes from minus to plus (from low level to high level) and exceeds the reference level REF (first level). When it is detected that the level of the detection signal S1 of the sensor has crossed zero), the level of the detection signal S2 of the second sensor is checked, and when the level of the detection signal S2 of the second sensor exceeds the reference level REF, It is determined that the N pole (high level) has been detected. In this case, in this embodiment, logic 1 is set as the first logic. On the other hand, when the angle detection circuit 100 detects that the level of the detection signal S1 of the first sensor goes from minus to plus (from low to high) and exceeds the reference level REF, the detection signal of the second sensor When the level of S2 is less than or equal to the reference level REF, it is determined that the S pole (low level) has been detected. In this case, in this embodiment, logic 0 is set as the second logic.
FIG. 2B shows a logical state obtained by the determination in the angle detection circuit 100 in this way.

  In addition, when a digital signal output type sensor is used as the first detection sensor and the second detection sensor, the detection signal S1 of the first sensor and the detection signal S2 of the second sensor to the angle detection circuit 100 are: For example, since it is sent as a digital pulse illustrated in FIGS. 3A and 3C, the detection signal S1 of the first sensor in the angle detection circuit 100 goes from minus to plus (from low level to high level) to the reference level REF. It is preferable to use a digital signal output type sensor as the first detection sensor and the second detection sensor, since the recognition of the time point exceeding the threshold value and the determination of the detection signal of the second detection sensor are facilitated.

Angle Detection Circuit The processing content of the angle detection circuit 100 will be described.
(1) Logic determination As described above, the angle detection circuit 100 detects that the level of the detection signal S1 of the first sensor is from minus to plus (from low level to high level) and exceeds the reference level REF, for example. When it is recognized, it is determined whether or not the detection signal S2 of the second sensor exceeds the reference level REF. The angle detection circuit 100 generates a logic 1 pulse when the detection signal S2 of the second sensor exceeds the reference level REF (when it is high). On the other hand, when the detection signal S2 of the second sensor is equal to or lower than the reference level REF (when it is low level), a logic 0 pulse is generated.

(2) Processing of Pulse Train The angle detection circuit 100 is provided with, for example, a serial register, and every time the angle detection circuit 100 makes the above determination for each magnetic pole part, a logical 1 or a logical 0 of the determination result Are input to the serial register.
The serial register holds the latest 6 consecutive pulses. That is, the magnetic pole detection results of six consecutive magnetic pole portions in the magnetic pole portion 12 are held.

(3) Angle calculation The angle detection circuit 100 has a memory, in which six time-series pulses and angles at that time are stored.
For example, in the example of Table 1 described above, the following pulse train and corresponding angle data are stored in the memory.

[Table 2]
(1) Range of 0 to 60 degrees, “000000”, 60 degrees (2) Range of 10 to 70 degrees, “000001”, 70 degrees (3) Range of 20 to 80 degrees, “000010” , 80 degrees (4) 30-90 degrees range, "000100" 90 degrees (5) 40-100 degrees range, "001000" 100 degrees (6) 50-110 degrees range , "010000", 110 degrees (7) 60 to 120 degrees, "100001", 120 degrees (8) 120 to 180 degrees, "100010", 180 degrees (9) 180 to 240 degree range, “10011”, 240 degree (10) 240-300 degree range, “100100”, 300 degree (11) 300-360 degree range, “111111”, 360 degree ( 2) from 330 to 030 degrees in the range, the time of "111000", 30 degrees

The angle detection circuit 100 reads the corresponding angle from the memory by using the 6-bit held data of the serial register, that is, the 6-bit pulse train data, as an address of the memory, for example.
For example, the binary number “000000” is decimal address data, and the binary number “111111” is decimal number 63 address data. In this example, 0 to 64 pieces of angle data are stored in the memory.

As described above, the absolute angle of the rotating body 10 can be detected by the angle detection circuit 100.
That is, in the present embodiment, the absolute angle of the rotating body at an arbitrary position with an accuracy of an angle that is an integral multiple of the angle occupied by one magnetic pole part (the angle occupied by a plurality of magnetic pole parts that define the combination of the above-mentioned sequence). Can be determined uniquely. As a result, an arbitrary absolute angle of the rotating body can be detected early. Therefore, the crank angle detection encoder of the present embodiment can quickly detect an arbitrary position of the crankshaft, for example, a top dead center starting point.
The angle detection circuit 100 has a simple logic determination, uses a simple circuit called a serial register, has a small memory capacity, and can be easily configured as a whole.

Application to Rotational Speed Detection The rotational speed of the rotating body 10 can also be detected using the encoder of the present embodiment described above. A case where the rotational speed of the rotating body 10 is detected using the encoder of the present embodiment will be described.
In this example, when the detection signal S1 of one sensor formed by equal distribution goes from minus to plus (low level to high level) and exceeds the reference level REF (starting position of the first magnetic pole portion) is sequentially detected. Then, the rotational speed of the rotating body 10 can be obtained from the time interval of the detection points.

Experimental Example An experimental example performed for use as a crank angle detection encoder will be described.
The magnetic pole portion 12 formed on the encoder rotating shaft 10 is usually separated from the first magnetic detection sensor 1 and the second magnetic detection sensor 2 by a gap (gap) of about 1 to 2 mm.
In this embodiment, since the occupation ratios of the N pole and the S pole in one magnetic pole portion are different, the magnetization distributions of the N pole and the S pole in one magnetic pole portion are not uniform. Therefore, for example, a magnetic pole pattern capable of detecting the magnetic flux of each magnetic pole portion under the gap is required.
4A and 4B, EMF analysis was performed on the magnetic field of the magnetic pole portion 12 when the gap was set to 1.5 mm and when the gap was set to 2.0 mm, and the accuracy of the magnetic force and the pitch of the magnetic pole portion was calculated. It is a graph which shows that.

The maximum value of the magnetic force transitions to the N-pole side when shifting from the A-pole type pattern to the B-pole type pattern at a position of 70 degrees. The pitch accuracy at that time deteriorates before and after that.
From the above example, it can be seen that in this experimental example, the pitch accuracy is maintained even when the gap is 2.0 mm. In this example, the occupation ratios of the N pole and the S pole are 40% and 60%, respectively.
For example, it has been found that the accuracy decreases when the occupation ratios of the N pole and the S pole are 30% and 70%, respectively. On the other hand, if the occupation ratio between the N pole and the S pole is small, the gap and pitch accuracy are advantageous. However, for example, when the occupation ratio is 45% or 55%, the S pole and the N pole are almost half of the occupation ratio, and there are variations in the position accuracy and angle detection accuracy of the first detection sensor 1 and the second detection sensor 2. May occur.
As described above, in the example, a gap of 1 to 2 mm and an occupation ratio of 40 ± 3% and 60 ± 3% were preferable.

  Needless to say, there are optimum values different from the above-described occupation ratio if conditions such as the size of the rotating shaft 10, the number of magnetic poles, and the gap are different. Therefore, the above experimental example is only one example.

Second Embodiment In the first embodiment, as illustrated in FIG. 1, the case where two magnetic detection sensors 1 and 2 are used has been described.
However, even with one magnetic detection sensor, the absolute angle of the rotating shaft 10 can be detected. An example thereof will be described as a second embodiment.
The number of magnetic pole portions of the magnetic pole portion 12 provided on the rotating shaft 10 and the magnetic pole types in each magnetic pole portion, that is, the A magnetic pole type and the B magnetic pole type are the same as those in FIG.
In the angle detection circuit 100, the time from the rise to the fall of the detection of the N pole is measured from the detection signal from one magnetic detection sensor. This measurement time indicates the duty ratio between the N pole and the S pole of the magnetic pole part, which is the same as the duty ratio of the first sensor detection pulse PLS1 in the first embodiment.
The angle detection circuit 100 processes the case where the duty ratio is large, for example, as a magnetic pole part of the B magnetic pole type, and sets it to logic 1, for example.
Hereinafter, the angle detection circuit 100 can detect the angle of the rotating shaft 10 by the same processing as in the first embodiment.

  Note that when one magnetic detection sensor is used, it is assumed that the rotating body 10 is rotating at a constant speed. Therefore, when the rotation speed at which the rotating shaft 10 starts to rotate is not stable. It is accurate to detect the angle using a plurality of continuous pulses in which the rotation of the rotating body 10 thereafter is stable, for example, 6 pulses, by invalidating about 1 to 2 pulses at the beginning of rotation. It is suitable for angle detection.

Third Embodiment With reference to FIG. 5, a cam angle encoder will be described as a fourth embodiment of the encoder of the present invention.
FIG. 5A is a diagram showing an example of a magnetization pattern of the magnetic pole portion 12 used in the crank angle detection encoder, and FIG. 5B is a diagram of the magnetization pattern of the magnetic pole portion 12 used in the cam angle encoder. It is a figure which shows an example. The crank angle detection encoder of FIG. 5A is shown as an example in order to show a comparison with the cam angle encoder.

  The combustion control of the engine is performed according to the position of the piston for each cylinder, that is, the crank angle. For example, in a four-cycle engine, the cylinder is burned every two revolutions of the crank. For example, in the case of a four-cylinder engine, the crank angle is burned every 180 degrees between 0 and 720 degrees. For this reason, in order to burn all four cylinders, it is necessary to rotate the crank twice, but the distinction between the first and second rotations is made based on the angle of the cam that rotates synchronously with a half cycle of the crank. Judgment based on.

Such a cam angle encoder that detects the cam angle can be configured based on the same technical idea of the present invention as the crank angle detection encoder described in the first to second embodiments. That is, as follows.
(1) A magnetic pole part is composed of two magnetic pole distribution patterns having different occupation ratios within one magnetic pole part, that is, the magnetic poles of the A magnetic pole type and the B magnetic pole type.
(2) For one rotation of the rotating shaft 10, as illustrated in FIG. 5B, the magnetic pole portion is disposed in each half of the crank angle detection encoder illustrated in FIG. FIG. 5A is substantially the same as that illustrated in FIG.
(3) Two magnetic detection sensors may be used as in the first embodiment, that is, the first magnetic detection sensor 1 and the second detection sensor 2, or as in the second embodiment. One magnetic detection sensor may be used.
(4) As the angle detection circuit 100, one that performs the above-described processing can be used.

  With such a cam angle encoder, it is possible to detect a half of one rotation of the rotating shaft 10, that is, a two-divided region.

  The encoder of the present invention is not limited to the crank angle detection encoder and the cam angle encoder described above, but can be used as various encoders for detecting the absolute angle of the rotating body. The resolution, the occupation ratio of the A magnetic pole type, and the B magnetic pole type are appropriately set according to the application.

  Further, for example, a non-magnetized portion can be provided between the N pole and the S pole in one magnetic pole portion. In this way, a non-magnetized portion appears between the N pole and the S pole, and the distinction between the two magnetization regions becomes clear.

Note that the magnetic detection sensor and the plurality of magnetic pole portions need only be in relative positions.
For example, as described above, the rotating body 10 may be provided with a plurality of magnetic pole portions, and the magnetic detection sensors 1 and 2 may be provided on the fixed portion. 1 and 2 may be provided, and a plurality of magnetic pole portions 12 may be provided in the fixed portion.

  The above-described embodiment and illustration are merely examples, and do not limit the present invention.

FIG. 1 is a diagram showing a configuration of a crank angle detection encoder as an embodiment of an encoder device of the present invention. FIG. 1 (A) is a schematic configuration diagram of the encoder device, and FIG. 1 (B) is a diagram of FIG. 2) is a diagram showing a positional relationship between the magnetic pole portion provided on the rotating shaft illustrated in FIG. FIG. 2 is a diagram showing the pattern of the magnetic pole part illustrated in FIG. 1 and its determination result. FIG. 2 (A) shows the magnetic pole pattern of the magnetic pole part shown in FIG. 1, and FIG. A result is shown and FIG.2 (C) is a figure which shows a magnetic pole type. 3A and 3B are diagrams showing the detection of the magnetization state and the logic determination result. 4A and 4B show that the magnetic field of the magnetic pole part when the gap is 1.5 mm and 2.0 mm is analyzed by EMF, and the accuracy of the magnetic force and the pitch of the magnetic pole part is calculated. It is a graph which shows. FIGS. 5A and 5B are diagrams showing a cam angle encoder as a fourth embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 1st magnetic detection sensor, 2 ... 2nd magnetic detection sensor 10 ... Rotary shaft, 12 ... Magnetic pole part 100 ... Angle detection circuit

Claims (3)

A plurality of magnetic pole portions disposed or formed along the circumference of the rotating body;
A magnetic detection sensor for detecting a magnetization signal from the magnetic pole portion;
An angle detection circuit, and
Each of the plurality of magnetic pole portions is either a first magnetic pole type in which a first magnetic pole region is wider than a second magnetic pole region or a second magnetic pole type in which a first magnetic pole region is narrower than a second magnetic pole region. Configured,
The plurality of magnetic pole portions are configured such that combinations of the sequence of the first magnetic pole type and the second magnetic pole type of the plurality of magnetic pole portions are different along the circumference of the rotating body. And
The angle detection circuit holds data indicating correspondence between a combination of the sequence of the first magnetic pole type and the second magnetic pole type and the angle of the rotating body at that time, and is detected by the magnetic detection sensor An angle of the rotating body is determined based on a combination of the ordered sequences of signals.
Encoder. A magnetic detection sensor provided on the rotating body;
A plurality of magnetic pole portions disposed or formed at positions corresponding to the rotation of the rotating body, relative to the rotation position of the magnetic detection sensor provided on the rotating body,
An angle detection circuit, and
Each of the plurality of magnetic pole portions is either a first magnetic pole type in which a first magnetic pole region is wider than a second magnetic pole region or a second magnetic pole type in which a first magnetic pole region is narrower than a second magnetic pole region. Configured,
The plurality of magnetic pole portions are configured such that combinations of the sequence of the first magnetic pole type and the second magnetic pole type of the plurality of magnetic pole portions are different along the circumference of the rotating body. And
The angle detection circuit holds data indicating correspondence between a combination of the sequence of the first magnetic pole type and the second magnetic pole type and the angle of the rotating body at that time, and is detected by the magnetic detection sensor An angle of the rotating body is determined based on a combination of the ordered sequences of signals.
Encoder. The magnetic detection sensor has a first magnetic detection sensor and a second magnetic detection sensor arranged at intervals capable of detecting a wide magnetic pole region in each magnetic pole portion,
The angle detection circuit has a first logic pulse signal indicating whether each magnetic pole portion is the first magnetic pole type or the second magnetic pole type based on detection signals from the first magnetic detection sensor and the second magnetic detection sensor. Otherwise, a second logic pulse signal is generated, and the angle of the rotating body is detected based on a sequence of these pulse signals.
The encoder according to claim 1 or 2.

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