JP2006038773A - Device for detecting rotation angle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for detecting rotation angle for reducing cost by means of simplification of a structure and suppression of the number of components. <P>SOLUTION: The rotation angle sensitive device comprises a rotation angle sensor 10 (a magnet 11, a first magnetoresistive element 12 and a second magnetic resistant element 13 changing resistant values due to change of magnetic fields, and a first comparator 15 and a second comparator 16 for binarizing an electrical signal (A point) by different thresholds), a gear 20 fixed on a crankshaft and having a number of teeth 21, and ECU 30 (an output pattern acquiring part 35 for continuously acquiring output patterns on the basis of a state (Hi or Lo) of each of binary signals output from the rotation angle sensor 10, a storing part 33 successively storing the output patterns, a substitution part 36 stored in the storing part 33 by substituting the output patterns at prescribed intervals from among successively storing output patterns for the other output patterns, and a rotation direction sensitive part 37 detecting a rotation direction of the crankshaft, on the basis of order of successively stored output patterns). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rotation angle detection device, and more particularly to a rotation angle detection device using a magnetoresistive element.

  In general, gasoline engines, diesel engines, and the like (hereinafter simply referred to as “engines”), which are internal combustion engines mounted on passenger cars, trucks, and the like, are controlled by an ECU, and therefore, as engine operating state information, Rotation speed and crank angle are required. Therefore, a rotation angle sensor is attached to the engine so that the ECU can acquire the engine speed and the crank angle. The rotation angle sensor outputs a pulse signal to the ECU based on the rotation angle of the crankshaft as the crankshaft rotates. The ECU detects the rotation angle of the crankshaft based on this pulse signal. Here, the ECU also detects the position of the piston of each cylinder of the internal combustion engine (that it is located at the top dead center of the piston of each cylinder) by this pulse signal. However, since the output of the conventional rotation angle sensor is weak when the internal combustion engine is running at a low speed, it is difficult for the ECU to detect the exact rotation angle of the crankshaft and the exact position of the piston of each cylinder. . Therefore, when the conventional rotation sensor is used, there is a problem that the ECU cannot determine the exact position of the piston of each cylinder, that is, the cylinder when starting the engine. In an internal combustion engine equipped with a conventional rotation angle sensor, as described above, since cylinder discrimination cannot be performed when the internal combustion engine is started, the ECU detects the rotation of the crankshaft by a pulse signal from the rotation angle sensor. The startability of the internal combustion engine is ensured by performing fuel injection control that injects fuel into all cylinders in response to an injection signal from the engine.

  Therefore, in order to solve the above problems, as shown in Patent Document 1, the ECU can accurately detect the rotation angle of the crankshaft and the position of the piston of each cylinder even when the internal combustion engine is rotating at a low speed. A rotation angle sensor that outputs a pulse signal has been proposed. This rotation angle sensor outputs a pulse signal to the ECU based on a change in a magnetic field, and includes a gear that is a detection target made of a magnetic material, a magnet that faces the gear, a gear and a magnet And an element (magnetoresistive element, Hall element) that changes electrically due to a change in magnetic field, and a comparator that converts an electric signal into a pulse signal. The gear is fixed to the crankshaft, and a magnetic field is generated between the gear and the magnet. This magnetic field changes as the crankshaft rotates and the gear rotates with it. Specifically, the magnetic field changes as the distance between the teeth of the same shape formed on the outer peripheral surface of the gear at equal intervals and the magnet changes. For example, the magnetic field increases as the distance between the teeth and the magnet approaches. When you leave, the magnetic field becomes weaker. The element is electrically changed by the change of the magnetic field, and an electric signal corresponding to the change of the magnetic field is output to the comparator. The comparator binarizes the input electrical signal with a threshold value and outputs a pulse signal to the ECU. The ECU detects the rotation angle of the gear, that is, the rotation angle of the crankshaft, based on this pulse signal. That is, in the conventional rotation angle sensor, the magnetic field changes even at a low speed of the internal combustion engine, so that the ECU can detect an accurate rotation angle of the crankshaft and an accurate position of the piston of each cylinder.

JP-A-10-170533

  By the way, the ECU needs to detect the rotation direction of the crankshaft in order to prevent damage to the internal combustion engine. However, in the rotation angle detection device, since the waveform of the pulse signal output to the ECU is the same during both forward and reverse rotation of the crankshaft, the rotational direction of the gear that the ECU is to be detected There is a problem that the rotation direction of the crankshaft cannot be detected, and the reverse rotation of the crankshaft cannot be detected. In addition, by using two rotation angle sensors, two pulse signals having a phase difference are output from each comparator to the ECU, and the ECU may detect the reverse rotation of the crankshaft from the phase difference between the two pulse signals. It is done. However, two rotation angle sensors are required, and there is a problem of cost increase due to complicated structure and an increased number of parts.

  The present invention has been made in view of the above, and an object of the present invention is to provide a rotation detection device capable of reducing the cost by simplifying the structure and suppressing the number of parts.

  In order to solve the above-described problems and achieve the object, in the present invention, in the rotation angle detection device for detecting the rotation angle of the detection target, the detection target having a large number of teeth formed at equal intervals in the rotation direction. And a first magnetoresistive element and a second magnetism whose resistance value changes due to a change in a magnetic field generated between the magnet to be detected and the magnet. A first comparator and a second comparator for inputting an electrical signal between a resistance element and the first magnetoresistive element and the second magnetoresistive element, and binarizing the electrical signal based on different threshold values; Output pattern acquisition means for continuously acquiring output patterns based on the Hi state and Lo state of the binarized signals output from the first comparator and the second comparator, Storage means for sequentially storing output patterns obtained successively; replacement means for replacing output patterns at predetermined intervals among the output patterns to be sequentially stored with other output patterns and storing them in the storage means; Rotation direction detecting means for detecting the rotation direction of the detection target based on the order of the output patterns sequentially stored.

  According to the present invention, in the rotation angle detection device, the rotation angle of the detection target is determined based on the Hi state and the Lo state of the binarized signal output from at least one of the first comparator and the second comparator. A rotation angle detection unit for detecting the rotation direction of the detection target when the rotation number of the detection target based on the detected rotation angle of the detection target is equal to or less than a predetermined rotation number; It is characterized by detecting a direction. Here, the predetermined number of rotations refers to the number of rotations at which the rotation direction of the detection target starts to be reversed.

  In the present invention, the rotation angle detection device further includes reference position detection means for detecting a reference position of a detection target based on the continuously acquired output pattern, and the storage means includes the detection target. The condition is that the output patterns obtained continuously are sequentially stored on condition that the reference position of the object is detected.

  According to these inventions, when the output patterns based on the Hi state and the Lo state of the binarized signals output from the two comparators having different threshold values are sequentially stored in the order in which they are successively acquired, Of the output patterns that are acquired automatically, the output patterns at predetermined intervals are replaced with other output patterns. That is, the order of the stored output patterns is different from the order of the output patterns actually acquired continuously. Therefore, the order of the output patterns that are continuously acquired is the same regardless of the rotation direction of the detection target, but when the rotation direction of the detection target is reversed, the output pattern stored immediately before is reversed. The order of the output pattern obtained after the output is different from the order of the stored output patterns. Thereby, the rotation direction of the detection target can be detected by one rotation angle sensor including two comparators.

  According to the present invention, in the rotation angle detection device for detecting the rotation angle of the detection target, the detection target having a large number of teeth formed at equal intervals in the rotation direction and the position facing the detection target teeth A first magnetoresistive element and a second magnetoresistive element whose resistance values change due to a change in a magnetic field generated between the magnet to be detected and the magnet, the first magnetoresistive element and the A hysteresis comparator configured by a Schmitt circuit that receives an electrical signal from the second magnetoresistive element and binarizes the electrical signal, and a Hi state period of the binarized signal output from the hysteresis comparator, Rotation direction detecting means for detecting the rotation direction of the detection target based on the ratio to the period of the Lo state.

  In the rotation angle detecting device, the tooth to be detected is formed such that the width of the tooth is wider than the width of the tooth gap.

  According to these inventions, the binarized signal output from one hysteresis comparator having different thresholds when the voltage of the input electric signal rises and falls is the period of the Hi state in the rotation direction of the detection target. And the Lo period are different. That is, the ratio between the period of the Hi state and the period of the Lo state differs depending on the rotation direction of the detection target. Thereby, the rotation direction of the detection target can be detected by one rotation angle sensor including one hysteresis comparator.

  In the rotation angle detecting device, the initial resistance value of the first magnetoresistive element is different from the initial resistance value of the second magnetoresistive element.

  According to the present invention, the voltage change of the electrical signal output to the hysteresis comparator can be kept long on the low voltage side, and even if the width of the tooth to be detected and the width of the tooth gap are the same, the hysteresis comparator The difference between the period of the Hi state and the period of the Lo state of the pulse signal output from can be widened. Therefore, even if the width of the tooth to be detected and the width of the tooth gap are the same, the ratio between the period of the Hi state and the period of the Lo state during the normal rotation of the object to be detected and the state of the Hi state during the reverse rotation The difference between the ratio of the period and the period of the Lo state can be widened. Thereby, the rotation direction detection means can detect the rotation direction of the detection target.

  In the above rotation angle detection device, the width of the tooth gap is 1.5 times or more the width of the tooth.

  According to the present invention, the difference between the output period of the Hi state and the output period of the Lo state of the pulse signal output from the hysteresis comparator can be reliably widened. Accordingly, the difference between the ratio of the Hi state period to the Lo state period during the forward rotation of the detection target and the ratio between the Hi state period and the Lo state period during the reverse rotation can be reliably widened. it can. Thereby, the rotation direction detection means can reliably detect the rotation direction of the detection target.

  The rotation angle detection device according to the present invention can detect the rotation direction of the detection target by using two rotation comparators having different threshold values or one hysteresis comparator having different threshold values by using the rotation angle sensor. As compared with the case where the rotation direction of the object to be detected is detected by using one of them, the structure can be simplified and the cost can be reduced by suppressing the number of parts.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the following Example. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same. In the following embodiments, a case where the rotation detection device is attached to an engine and a gear to be detected is a rotating body that rotates with a crankshaft will be described, but the present invention is not limited to this. Any object can be used as long as the object to be detected rotates.

  FIG. 1 is a diagram illustrating a configuration example of the rotation angle detection device according to the first embodiment. FIG. 2 is a partial enlarged view of the rotation angle detection device according to the first embodiment. As shown in FIGS. 1 and 2, the rotation angle detection device 1-1 according to the first embodiment is based on the rotation angle sensor 10, the gear 20 that is the detection target, and the rotation angle of the detection target 20. The ECU 30 is configured to detect the rotation angle of the shaft 40.

  The rotation angle sensor 10 is disposed in the vicinity of the gear 20, and includes a magnet 11, a first magnetoresistance element 12, a second magnetoresistance element 13, a power supply 14, a first comparator 15, and a second comparator 16. It is comprised by. The magnet 11 generates a magnetic field toward the gear 20 described later, and is disposed at a position facing the teeth 21 of the gear 20. The first magnetoresistive element 12 and the second magnetoresistive element 13 are electrically changed by the change of the magnetic field, that is, the resistance value is changed. The first magnetoresistive element 12 and the second magnetoresistive element 13 are located between the magnet 11 and the teeth 21 of the gear 20 and are arranged in the rotational direction of the gear 20. Here, the first magnetoresistive element 12 and the second magnetoresistive element 13 have the same initial resistance value. Therefore, by arranging as described above, the change in the resistance value due to the change in the magnetic field generated between the magnet 11 and the tooth 21 of the gear 20 becomes the same, and the resistance value at the constant magnetic field strength becomes the same. . The first magnetoresistive element 12 and the second magnetoresistive element 13 are connected in series, and both ends thereof are connected to the power source 14 to form a series circuit.

The first comparator 15 and the second comparator 16 are respectively connected between the first magnetoresistive element 12 and the second magnetoresistive element 13 (point A in FIG. 2). The first comparator 15 and the second comparator 16 input a voltage change between the first magnetoresistive element 12 and the second magnetoresistive element 13 as an electric signal, and binarizes the electric signal. A pulse signal as a signal is output to the ECU 30. In the first comparator 15 and the second comparator 16, different threshold values V _A and V _B are set in order to binarize the electrical signal. The threshold V _A and the threshold V _B are lower than the center voltage so that one is higher than the center voltage of the voltage change between the first magnetoresistive element 12 and the second magnetoresistive element 13. Is set to

  The gear 20 is an object to be detected, is made of a magnetic material, and is fixed to the crankshaft 40 of the engine. Therefore, when the crankshaft rotates, the gear 20 also rotates in the same direction. A plurality of teeth 21 are formed on the outer peripheral surface of the gear 20 at equal intervals in the rotation direction of the crankshaft. The width W1 of the tooth 21 is set wider than the width of the first magnetoresistive element 12 and the second magnetoresistive element 13 in the rotation direction of the crankshaft 40. Further, the width W2 of the tooth gap 22 formed between the teeth 21 is set to be larger than the width W1 of the teeth 21, and preferably 1.5 times or more. Here, reference numeral 23 denotes a missing tooth portion for detecting a reference position of the gear 20 which is a reference for obtaining an accurate position (for example, being located at the top dead center) of the piston of each cylinder of the engine. .

  Based on the pulse signals output from the first comparator 15 and the second comparator 16, the ECU 30 rotates the crankshaft necessary for obtaining the piston position, engine speed, and crank angle of each cylinder (not shown). Information necessary for engine operation control, such as the angle and the rotation direction of the crankshaft, is acquired, and engine operation control (fuel injection control, ignition control) is performed based on this information and a map stored in the storage unit. Etc.).

  Specifically, the input / output port (I / O) 31 for inputting / outputting the input signal and the output signal, a processing unit 32, and the storage unit 33 for storing the map and an output pattern described later. ing. The processing unit 32 includes a reference position detection unit 34, an output pattern acquisition unit 35, a replacement unit 36, a rotation direction detection unit 37, and a rotation angle detection unit 38. The rotation angle detection device includes a memory 32 and a CPU (Central Processing Unit), and loads and executes a program based on an operation method of the rotation angle detection device 1-1 according to the first embodiment. The operation method 1-1 may be realized. The storage unit 33 is a non-volatile memory such as a flash memory, a volatile memory such as a ROM (Read Only Memory) that can only be read, or a volatile that can be read and written such as a RAM (Random Access Memory). The memory can be configured by a combination of these. In the first embodiment, the operation method of the rotation angle detection device 1-1 is realized by the ECU 30, but is not limited to this, and may be realized by a control device formed separately from the ECU 30. good.

  The reference position detection unit 34 detects the reference position of the gear 20 by detecting the missing tooth portion 23 of the gear 20 based on the output pattern continuously acquired by the output pattern acquisition unit 35. The output pattern acquisition unit 35 generates an output pattern based on the Hi state and Lo state of the two pulse signals from the first comparator 15 and the second comparator 16 that are input via the input / output port 35. The output pattern is obtained continuously. When the replacement unit 36 sequentially stores the output patterns continuously acquired by the output pattern acquisition unit 35 in the storage unit 33, among the stored output patterns, the replacement unit 36 outputs an output pattern for each predetermined interval as another output pattern. And is stored in the storage unit 33. The rotation direction detection unit 37 detects the rotation direction of the gear, that is, the rotation direction of the crankshaft 40 based on the order of the output patterns sequentially stored in the storage unit 33. The rotation angle detection unit 38 detects the rotation angle of the detection target based on the Hi state and Lo state of the two pulse signals output from the first comparator 15 and the second comparator 16 input via the input / output port 35. That is, the rotation angle of the crankshaft 40 is detected.

  Next, an operation method of the rotation angle detection device 1-1 according to the first embodiment will be described. FIG. 3 is an operation flow of the rotation angle detection apparatus according to the first embodiment. FIGS. 4A to 7 are explanatory diagrams of the operation of the rotation angle detection device 1-1 according to the first embodiment. Here, an operation method in the case of detecting the rotation direction of the crankshaft 40 in the rotation angle detection device 1-1 according to the first embodiment will be described. The detection of the rotation angle of the crankshaft 40 and the detection of the reference position of the gear 20 will be described as appropriate during the following operation method.

  First, the operation of the rotation angle sensor 10 including the two first comparators 15 and the second comparator 16 will be described. As shown in FIG. 4A, when the crankshaft 40 rotates in the forward direction, the gear 20 also rotates in the same direction, and the distance between the tooth 21 of the gear 20 and the magnet 11 (not shown) changes. Thereby, the magnetic field generated between the magnet 11 and the gear 20 becomes stronger as the distance between the magnet and the tooth 21 becomes shorter, and becomes weaker as the distance becomes longer. Therefore, the first magnetoresistive element 12 and the second magnetoresistive element 13 located between the magnet 11 and the tooth 21 of the gear 20 have a resistance value between the magnet 11 and the gear 20 when the energized state. The resistance value changes according to the change in the generated magnetic field. That is, the first magnetoresistive element 12 and the second magnetoresistive element 13 change in resistance value according to the distance from the gear 20 to the tooth 21, and as shown in FIG. And the voltage between the 2nd magnetoresistive element 13 changes. This voltage change is output to the first comparator 15 and the second comparator 16 as an electrical signal.

The first comparator 15 binarizes the input electrical signal shown in FIG. 4B with the threshold value V _A and outputs a pulse signal to the ECU 30. Pulse signal output from the first comparator 15, as shown in Figure 4-3, the Hi state when voltage is less than the threshold value V _A of the electrical signal, when is lower than the threshold V _A becomes Lo state. The second comparator 16 binarizes the input electrical signal shown in FIG. 4B with the threshold value V _B and outputs a pulse signal to the ECU 30. Pulse signal output from the second comparator 16, as shown in Figure 4-4, the Hi state when voltage is less than the threshold value V _B of the electrical signal, is is lower than the threshold value V _B becomes Lo state.

  In the operation of the rotation angle detection device 1-1 according to the first embodiment, as shown in FIG. 3, it is first determined whether or not the processing unit 32 of the ECU 30 has output an engine stop signal (step ST101). Specifically, the ECU 32 outputs a signal for ending the operation control of the engine to the engine, and determines whether or not the crankshaft 40 is idling. This step ST101 is repeated until an engine stop signal is output.

  Next, when the processing unit 32 determines that the engine stop signal has been output, the rotation angle detection unit 38 of the processing unit 32 detects the rotation angle of the gear 20, that is, the rotation angle of the crankshaft 40. The engine speed Ne is acquired based on the rotation angle (step ST102). Specifically, the rotation detection unit 38 changes the timing of the change between the Hi state and the Lo state of any one of the pulse signals output from the first comparator 15 and the second comparator 16 (from the Lo state to the Hi state and / or Hi state). From the state to the Lo state), the rotation angle of the gear 20 is detected based on this count number, and the rotation angle of the crankshaft 40 is detected. Then, the engine speed Ne is acquired from the rotation angle of the crankshaft 40.

  The rotation angle detection unit 38 detects the rotation angle of the crankshaft 40 in the Hi state and the Lo state of both pulse signals output from the first comparator 15 and the second comparator 16 as well as both pulse signals. You may go from the change. In this case, the number of counts during one rotation of the gear 20 can be increased by counting the timing of the change between the Lo state and the Hi state from the two pulse signals. Therefore, the rotation angle of the crankshaft 40 can be detected finely, and the engine speed Ne can be acquired with high accuracy. Here, it is preferable to detect the rotation angle of the crankshaft 40 based on one of the two pulse signals at the time of high engine rotation. Thereby, the burden of ECU30 at the time of high engine rotation can be reduced.

  Next, the processing unit 32 of the ECU 30 determines whether or not the acquired engine speed Ne is equal to or less than a predetermined speed Ne1 (step ST103). Here, the predetermined rotational speed Ne1 is reduced due to engine friction in which the rotational speed of the crankshaft 40, which is idling with the engine operation control stopped, acts in the direction opposite to the forward rotation direction of the crankshaft 40, This is the rotation speed (for example, 400 rpm) at which the crankshaft 40 may start to reverse from the normal rotation due to the friction of the engine. That is, it is determined whether or not the engine rotational speed Ne based on the rotational angle of the crankshaft 40 detected by the rotational angle detector 38 is a rotational speed at which the crankshaft 40 may reverse from the normal rotation. Note that steps ST102 and ST103 are repeated until the acquired engine speed Ne becomes equal to or less than the predetermined engine speed Ne1.

  Next, when it is determined that the engine speed Ne acquired by the processing unit 32 is equal to or less than the predetermined rotational speed Ne1, the output pattern acquisition unit 35 of the processing unit 32 outputs 2 from the first comparator 15 and the second comparator 16. Acquisition of an output pattern based on the Hi state and Lo state of the two pulse signals is started (step ST104). The output pattern acquisition unit 35 generates a plurality of output patterns based on the Hi state and Lo state of the two pulse signals. Specifically, as shown in FIG. 4-6, an output pattern is generated by combining the Hi state and Lo state of the pulse signal from the first comparator 15 and the Hi state and Lo state of the pulse signal from the second comparator 16. To do. For example, if the pulse signal from the first comparator 15 is in the Lo state and the pulse signal from the second comparator 16 is in the Hi state at this time, an output pattern of “LH” is generated. When the pulse signal from the first comparator 15 is in the Lo state and the pulse signal from the second comparator 16 at this time is in the Lo state, an output pattern of “LL” is generated. Furthermore, when the pulse signal from the first comparator 15 is in the Hi state and the pulse signal from the second comparator 16 at this time is in the Hi state, an output pattern of “HH” is generated.

  Here, since the pulse signal from the first comparator 15 and the pulse signal from the second comparator 16 repeat the Hi state and the Lo state at regular intervals (except in the case of a reference position described later), the output pattern generated is Change periodically. Specifically, the output pattern periodically changes in the order of “LL”, “LH”, “HH”, and “LH”. The output pattern acquisition unit 35 continuously acquires a plurality of output patterns that change periodically.

  Next, the reference position detection unit 34 of the processing unit 32 determines whether or not the reference position of the gear 20 has been detected (step ST105). The reference position of the gear 20 is detected using a missing tooth portion 23 formed on the gear 20. Specifically, when the gear 20 rotates with the rotation of the crankshaft 40 and the missing tooth portion 23 passes near the rotation angle sensor 10, the tooth gap 22 passes near the rotation angle sensor 10. In comparison, the state in which the first magnetoresistive element 12 and the second magnetoresistive element 13 and the tooth 21 are separated from each other is maintained for a long time. Therefore, as shown in FIG. 4-1, when the distance between the chipped portion 23 and the first magnetoresistive element 12 and the second magnetoresistive element 13 is maintained constant and long, as shown in FIG. The portion corresponding to the missing tooth portion 23 of the electric signal output to the first comparator 15 and the second comparator 16 is in a state where a constant voltage is maintained for a long time.

  The output pattern acquisition unit 35 generates a portion corresponding to the missing tooth portion 23 of the electrical signal as an output pattern “LH” based on the pattern signals output from the first comparator 15 and the second comparator 16. The output pattern “LH” generated corresponding to the missing tooth portion 23 is longer than any output period of the output pattern in which the output period changes periodically. Therefore, the reference position detection unit 34 detects the reference position of the gear 20 by detecting the output pattern “LH” having the longest output period among the output patterns continuously acquired by the output pattern acquisition unit 35. This step ST105 is repeated until the reference position of the gear 20 is detected.

  Next, when the reference position detection unit 34 detects the reference position of the gear 20, the processing unit 32 stores the output pattern continuously acquired by the output pattern acquisition unit 35 in the storage unit 33 (step ST106). That is, the processing unit 32 starts storing the output pattern in the storage unit 33 on the condition that the reference position of the gear 20 is detected, that is, as a trigger. Therefore, as shown in FIG. 4-5, when the storage unit 33 starts storing, the order of the output patterns continuously acquired by the output pattern acquisition unit 35 is generated corresponding to the missing tooth portion 23. The output pattern “LH” is 0, and the output patterns “LL”, “LH”, “HH”, and “LH” for one cycle are repeated.

  Next, the replacement unit 35 of the processing unit 32 replaces the output pattern at predetermined intervals among the output patterns continuously acquired from the reference position with another output pattern (step ST107). The output pattern acquisition unit 35 repeats the four output patterns “LL”, “LH”, “HH”, and “LH” after the output pattern “LH” generated corresponding to the missing tooth portion 23. The output pattern is acquired. Here, the predetermined interval may be set according to the number of output patterns for one cycle. For example, the order of output patterns to be acquired is counted, and the order is 4 (the number of output patterns for one cycle). The output pattern “LH” in the order (No. 2, No. 6, No. 10...) That becomes 2 when divided is replaced with another output pattern “LL” and stored in the storage unit 33. As a result, as shown in FIG. 4-6, the order of the output patterns after replacement actually stored in the storage unit 33 is the same as the output pattern “LL” and the output pattern in the order of the output patterns shown in FIG. The output pattern “LH” between “HH” is replaced with another output pattern “LL”. That is, the order of the stored output patterns shown in FIG. 4-6 is different from the order of the output patterns actually acquired continuously shown in FIG. 4-5.

  Next, the rotation direction detection unit 37 of the processing unit 32 compares the order of the output pattern stored immediately before and the acquired output pattern with the order of the stored output patterns (step ST108). Here, for example, when the output pattern “LH” acquired corresponding to the missing tooth portion 23 is number 0, the output shaft “LH” acquired by the output pattern acquisition portion 34 is the 12th output pattern “LH”. Assume that 40 changes from forward rotation to reverse rotation. In this case, as shown in FIG. 4-7, the output pattern acquisition unit 34 causes the output patterns “LL”, “LH”, “HH”, “ Output patterns (No. 12, No. 13, No. 14,...) Are successively acquired in the order in which “LH” is repeated. That is, the order of the output patterns obtained continuously during the forward rotation of the crankshaft 40 is the same as the order of output patterns obtained continuously during the reverse rotation. However, since the order of the output patterns sequentially stored in the storage unit 32 shown in FIG. 4-6 is after the replacement, adjacent outputs different from the order of the output patterns continuously acquired at the time of reverse rotation. There is a pattern order. That is, the rotation direction detection unit 37 of the processing unit 32 combines the output pattern acquired continuously and the output pattern stored in the storage unit 32 immediately before the output pattern is acquired (the stored output pattern, A comparison is made between a combination of the obtained output patterns in order and a combination of adjacent output patterns stored in the storage unit.

  Next, the rotation direction detection unit 37 of the processing unit 32 determines whether or not the same order as the order of the output pattern stored immediately before and the acquired output pattern is the order of the output pattern stored in the storage unit. Judgment is made (step ST109). If there is the same order, the crankshaft 40 is rotating forward, so steps ST106 to ST109 are repeated. On the other hand, if the same order is not found, it can be determined that the crankshaft 40 is rotating in reverse, and therefore the rotation direction detector 37 detects that the crankshaft 40 has been reversed (step ST110).

  As described above, the rotation angle detection device 1-1 according to the first embodiment uses the one rotation angle sensor 10 including the two comparators (the first comparator 15 and the second comparator 16) to detect the gear 20 that is the detection target. The rotation direction, that is, the rotation direction of the crankshaft 40 can be detected. Moreover, since the rotation direction detection part 37 of the process part 32 detects the rotation direction of the crankshaft 40 for every acquired output pattern, it can detect reverse rotation of the crankshaft 40 instantaneously.

  The rotation direction detection unit 37 of the processing unit 32 can also detect the rotation direction of the crankshaft based on the output period of the output pattern continuously acquired by the output pattern acquisition unit 35. As shown in FIG. 4-5, the output pattern continuously acquired by the output pattern acquisition unit 35 changes periodically. Here, two identical output patterns “LH” are included in one cycle. The output period of the same output pattern “LH” can be varied by making the width W 2 of the tooth gap 22 wider than the width W 1 of the tooth 21. This is because the width W2 of the tooth groove 22 is made wider than the width W of the tooth 21 so that the first magnetoresistive element 12 and the second magnetoresistive element 13 are closest to the tooth 21 and the tooth 21 This is because the difference with the most distant period can be widened, and this difference becomes the difference between the output periods of the same output pattern “LH”.

  The replacement unit 35 of the processing unit 32 replaces the output pattern “LH” having the shorter output period among the same output pattern “LH” with another output pattern “LL”. In this case, during forward rotation of the crankshaft 40, as shown in FIG. 4-5, the output pattern stored immediately before the acquired output pattern “LH” to be replaced is “LL”. On the other hand, at the time of reverse rotation of the crankshaft 40, as shown in FIG. 4-7, the output pattern stored immediately before the acquired output pattern “LH” to be replaced is “HH”. Then, the rotation direction detection unit 37 of the processing unit 32 determines whether the output pattern stored immediately before the acquired output pattern “LH” to be replaced is the output pattern “LL” or the output pattern “HH”. To do. Thereby, the rotation direction detection unit 37 of the processing unit 32 can detect the rotation direction of the crankshaft 40. That is, the rotation direction detection unit 37 of the processing unit 32 determines that the output shaft “HH” is stored immediately before the acquired output pattern “LH” to be replaced. To detect.

  FIG. 5 is a diagram illustrating a configuration example of the rotation angle detection device according to the second embodiment. FIG. 6 is a diagram illustrating a circuit configuration example of the hysteresis comparator. The rotation angle detection device 1-2 shown in FIG. 5 differs from the rotation angle detection device 1-1 shown in FIG. 1 in that one hysteresis having hysteresis instead of the two first comparators 15 and the second comparator 16 is used. This is the point where the comparator 17 is used. The basic configuration of the rotation angle detection device 1-2 shown in FIG. 5 is the same as the basic configuration of the rotation angle detection device 1-1 shown in FIG.

The hysteresis comparator 17 receives an electrical signal between the first magnetoresistive element and the second magnetoresistive element, binarizes the electrical signal, and outputs a pulse signal that is a binarized signal to the ECU 30. As shown in FIG. 5, the hysteresis comparator 17 is connected between the first magnetoresistive element 12 and the second magnetoresistive element 13, and the first magnetoresistive element 12 and the second magnetoresistive element 13 are connected to each other. The change in voltage is input as an electrical signal. As shown in FIG. 6, the hysteresis comparator 17 includes an operational amplifier 17a, two resistors 17b and 17c, a reference power supply 17d, and a Schmitt circuit (hysteresis circuit). The hysteresis comparator 17 has a characteristic that the threshold value V _C when the voltage of the input electric signal rises and the threshold value V _D when the voltage drops are different.

  Next, an operation method of the rotation angle detection device 1-2 according to the second embodiment will be described. FIG. 7 is an operation flow of the rotation angle detection apparatus according to the second embodiment. FIGS. 8-1 to 4 are operation explanatory diagrams of the rotation angle detecting device 1-2 according to the second embodiment. In the rotation angle detection device 1-2 according to the second embodiment shown in FIG. 5, the rotation angle detection unit 38 of the processing unit 32 detects the rotation angle of the crankshaft 40 and the reference position detection unit 34 determines the reference position of the gear 20. Since this is the same as that of the rotation angle detector 1-1 according to the first embodiment shown in FIG. 1, the description thereof is omitted.

  First, the operation of the rotation angle sensor 10 including one hysteresis comparator 17 will be described. As shown in FIG. 8A, when the gear 20 rotates in the same direction as the crankshaft 40 rotates forward, the change in the magnetic field generated between the magnet 11 and the gear 20 changes, and the first magnetoresistive element 12 and the second magnetoresistive element 13 change, and the voltage between the first magnetoresistive element 12 and the second magnetoresistive element 13 changes as shown in FIG. This voltage change is output to the hysteresis comparator 17 as an electrical signal.

The hysteresis comparator 17 binarizes the input electrical signal shown in FIG. 8B with the threshold value V _C and the threshold value V _D , and outputs a pulse signal to the ECU 30. As shown in FIGS. 8-3 and 8-4, the pulse signal output from the hysteresis comparator 17 is in a Hi state when the voltage exceeds the threshold value V _C when the voltage of the electrical signal rises, and the voltage becomes the threshold value when the voltage drops. When V _D or higher, the Lo state is entered.

In the operation of the rotation angle detection device 1-2 according to the second embodiment, as shown in FIG. 7, first, the rotation direction detection unit 37 of the processing unit 32 acquires the pulse signal output from the hysteresis comparator 17 ( Step ST201). Then, the rotation direction detection unit 37 acquires the duration T _Lo period T _Hi and Lo states of the Hi state of the obtained pulse signal (step ST 202).

Next, the rotation direction detection unit 37 determines whether or not the ratio T _Hi / T _Lo between the acquired period T _{Hi of the Hi} state and the period T _{Lo of the} Lo state is equal to or greater than a predetermined value T1 (step ST203). ). As shown in FIGS. 8-3 and 8-4, the pulse signal acquired by the rotation direction detection unit 37 is in a Hi state depending on the rotation direction of the gear 20 to be detected, that is, the rotation direction of the crankshaft 40. The difference between the period T _Hi and the period T _{Lo in the} Lo state is different. Specifically, as shown in FIG. 8C, in the pulse signal acquired when the crankshaft 40 is rotated forward, the period T _{Hi in the} Hi state is longer than the period T _{Lo in the} Lo state. On the other hand, as shown in FIG. 8-4, in the pulse signal acquired when the crankshaft 40 rotates in the reverse direction, the period T _{Hi in the} Hi state is shorter than the period T _{Lo in the} Lo state. Accordingly, the rotation direction detection unit 37 calculates the ratio T _Hi / T _Lo between the Hi state period (Lo state period) of the acquired pulse signal and the Lo state period (Hi state period) stored immediately before. Then, the calculated ratio T _Hi / T _Lo is compared with the predetermined value T1.

Here, the predetermined value T1 is such that the ratio T _Hi / T _Lo is 1 or more during forward rotation of the crankshaft 40, and the ratio T _Hi / T _Lo is less than 1 during reverse rotation of the crankshaft 40. To do. As shown in FIG. 5, the gear 20 has a width W2 of the tooth gap 22 wider than a width W1 of the tooth 21, so that the first magnetoresistive element 12 and the second magnetoresistive element 13 have teeth 21. The difference between the period closest to the tooth 21 and the period farthest from the tooth 21 can be widened, and this difference is the difference between the Hi state period and the Lo state period of the pulse signal output from the hysteresis comparator 17. It is because it becomes. In addition, in the said gear 20, it is preferable that the width W2 of the tooth gap 22 is set so that it may become 1.5 times or more of the width W1 of the tooth | gear 21. FIG. Thereby, the difference between the period of the Hi state and the period of the Lo state of the pulse signal output from the hysteresis comparator can be widened, and the ratio T _Hi / T _Lo at the time of forward rotation of the crankshaft 40 can be increased. The difference from the ratio T _Hi / T _Lo can be surely widened.

Then, since the rotational direction detection unit 37, if the ratio T _Hi / T _Lo of the period T _Lo period T _Hi and Lo states of the Hi state is equal to or greater than the predetermined value T1, the crankshaft 40 is rotating forward, Step ST202 to step ST203 are repeated. On the other hand, if the ratio T _Hi / T _Lo is less than T1, it can be determined that the crankshaft 40 is rotating in reverse at that time, so the rotation direction detection unit 37 detects that the crankshaft 40 has been reversed. (Step ST204).

  As described above, the rotation angle detection device 1-1 according to the second embodiment uses one rotation angle sensor 10 including one hysteresis comparator 17 to rotate the rotation direction of the gear 20, that is, the rotation of the crankshaft 40. The direction can be detected. Further, since the rotation direction detection unit 37 of the processing unit 32 detects the rotation direction of the crankshaft 40 for each of the Hi state or Lo state of the acquired pulse signal, the reverse rotation of the crankshaft 40 can be detected instantaneously. .

  In the above embodiment, by setting the width W2 of the tooth groove 22 of the gear 20 to be wider (1.5 times or more) than the width W1 of the tooth 21, the Hi state of the pulse signal output from the hysteresis comparator 17 is set. Although the difference is widened between the period and the period of the Lo state, the present invention is not limited to this. For example, the initial resistance value of the first magnetoresistive element 12 may be different from the initial resistance value 13 of the second magnetoresistive element. In this case, the voltage change of the electrical signal output to the hysteresis comparator 17 is maintained on the low voltage side for a long time. Therefore, even if the width W2 of the tooth groove 22 of the gear 20 and the width W1 of the tooth 21 are the same, the difference between the Hi state period and the Lo state period of the pulse signal output from the hysteresis comparator 17 is widened. Can do.

  As described above, the rotation angle detection device according to the present invention is useful for a rotation angle detection device that detects the reverse rotation of the crankshaft, and in particular, since one rotation angle sensor detects the reverse rotation of the crankshaft, It is suitable for cost reduction by simplification and suppression of parts count.

It is a figure which shows the structural example of the rotation angle detection apparatus concerning Example 1. FIG. It is a figure which shows the elements on larger scale of the rotation angle detection apparatus concerning Example 1. FIG. 2 is an operation flow of the rotation angle detection apparatus according to the first embodiment. It is a figure which shows the relationship between a 1st magnetoresistive element and a 2nd magnetoresistive element, and the gear to rotate. It is a figure which shows the electric signal output to a 1st comparator and a 2nd comparator. It is a figure which shows the pulse signal output to ECU from a 1st comparator. It is a figure which shows the pulse signal output to ECU from a 2nd comparator. It is a figure which shows the output pattern order at the time of forward rotation of a crankshaft. It is a figure which shows the output pattern order after replacement. It is a figure which shows the output pattern order at the time of reverse rotation of a crankshaft. It is a figure which shows the structural example of the rotation angle detection apparatus concerning Example 2. FIG. It is a figure which shows the circuit structural example of a hysteresis comparator. It is an operation | movement flow of the rotation angle detection apparatus concerning this Example 2. FIG. It is a figure which shows the relationship between a 1st magnetoresistive element and a 2nd magnetoresistive element, and the gear to rotate. It is a figure which shows the electric signal output to a hysteresis comparator. It is a figure which shows the pulse signal output to ECU from the hysteresis comparator at the time of forward rotation of a crankshaft. It is a figure which shows the pulse signal output to ECU from the hysteresis comparator at the time of reverse rotation of a crankshaft.

Explanation of symbols

1-1, 1-2 Rotation angle detection device 10 Rotation angle sensor 11 Magnet 12 First magnetoresistive element 13 Second magnetoresistive element 14 Power supply 15 First comparator 16 Second comparator 17 Hysteresis comparator 20 Gear (detection target)
21 teeth 22 tooth gaps 23 missing teeth 30 ECU
31 Input / Output Port 32 Processing Unit 33 Storage Unit 34 Reference Position Detection Unit 35 Output Pattern Acquisition Unit 36 Replacement Unit 37 Rotation Direction Detection Unit 38 Rotation Angle Detection Unit 40 Crankshaft

Claims (7)

In the rotation angle detection device for detecting the rotation angle of the detection target,
A detection target having a large number of teeth formed at equal intervals in the rotation direction;
A magnet disposed at a position facing the tooth to be detected;
A first magnetoresistive element and a second magnetoresistive element whose resistance values change due to a change in a magnetic field generated between the object to be detected and the magnet;
A first comparator and a second comparator for inputting an electrical signal between the first magnetoresistive element and the second magnetoresistive element, and binarizing the electrical signal based on different threshold values;
Output pattern acquisition means for continuously acquiring output patterns based on the Hi state and Lo state of the binarized signals output from the first comparator and the second comparator;
Storage means for sequentially storing the continuously acquired output patterns;
Of the output patterns to be sequentially stored, a replacement means for replacing the output pattern for each predetermined interval with another output pattern and storing it in the storage means;
A rotation direction detecting means for detecting a rotation direction of the detection target based on the order of the output patterns stored in sequence;
A rotation angle detection device comprising: A rotation angle detecting means for detecting a rotation angle of the detection target based on a Hi state and a Lo state of the binarized signal output from at least one of the first comparator and the second comparator;
The rotation direction detection means detects the rotation direction of the detection target when the rotation number of the detection target based on the detected rotation angle of the detection target is equal to or less than a predetermined rotation number. Item 2. The rotation angle detection device according to Item 1. A reference position detecting means for detecting a reference position of the detection target based on the continuously obtained output pattern;
The rotation angle detection device according to claim 1, wherein the storage unit sequentially stores the continuously obtained output patterns on condition that the reference position of the detection target is detected. In the rotation angle detection device for detecting the rotation angle of the detection target,
A detection target having a large number of teeth formed at equal intervals in the rotation direction;
A magnet disposed at a position facing the tooth to be detected;
A first magnetoresistive element and a second magnetoresistive element whose resistance values change due to a change in a magnetic field generated between the object to be detected and the magnet;
A hysteresis comparator configured by a Schmitt circuit that receives an electrical signal between the first magnetoresistive element and the second magnetoresistive element and binarizes the electrical signal;
A rotation direction detecting means for detecting a rotation direction of the detection target based on a ratio between an output period of the Hi state and an output period of the Lo state of the binarized signal output from the hysteresis comparator;
A rotation angle detection device comprising:   The rotation angle detection device according to claim 4, wherein the tooth to be detected is formed such that a width of the tooth is wider than a width of a tooth gap.   The rotation angle detection device according to claim 4, wherein an initial resistance value of the first magnetoresistive element is different from an initial resistance value of the second magnetoresistive element. The rotation angle detection device according to claim 5, wherein a width of the tooth gap is 1.5 times or more of a width of the tooth.

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