JP2016217850A - Rotational speed detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotational speed detector that can calculate amplitude increasing duration accurately when rotational speed of an output shaft of an engine is comparatively low.SOLUTION: A rotational speed detector comprises: a crank rotor that rotates along with an output shaft of an engine; a crank sensor that outputs a voltage waveform of which amplitude becomes smaller when rotational speed of the crank rotor becomes low; a calculation part that calculates the rotational speed of the output shaft on the basis of the voltage waveform; a motor that has a rotary shaft connected to the output shaft; a resolver that detects a rotation angle position of the rotary shaft and then outputs a detection signal corresponding to the rotation angle position; a measurement part that measures the rotational speed of the rotary shaft on the basis of the detection signal; and an amplification part that increases amplitude of the voltage waveform. When the rotational speed of the output shaft is equal to or less than prescribed speed, the calculation part calculates duration of increase in the amplitude of the voltage waveform by the amplification part, on the basis of the rotational speed of the rotary shaft to be measured by the measurement part.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a rotational speed detection device.

  2. Description of the Related Art Conventionally, a rotational speed detection device that detects a rotational speed of an axle by installing a rotor that rotates integrally with an axle in a magnetic field and detects a change in the magnetic field due to the rotation of the rotor is known (for example, Patent Document 1). See).

  Further, when the output shaft of the engine and the rotation shaft of the motor are connected, instead of a crank sensor that detects the angular position of the output shaft of the engine, a resolver that detects the angular position of the rotation shaft of the motor is used. A technique for calculating an angular position of an output shaft of an engine is known (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 07-84655 JP 2001-20797 A

  FIG. 1 is a diagram illustrating an example of a crank rotor 11 that rotates together with an output shaft of an engine. In order to calculate the rotational speed of the output shaft of the engine, a crank sensor is used which detects a change in the magnetic field generated by the movement of the teeth 12 due to the rotation of the crank rotor 11 by a coil and outputs a voltage waveform corresponding to the change in the magnetic field. There is a case. In this case, for example, as shown in FIG. 2, the crank sensor signal C input when the voltage waveform output from the crank sensor crosses the threshold value every cycle is detected, and the input interval time of the crank sensor signal C is detected. The rotational speed of the engine output shaft can be calculated.

  However, for example, as shown in FIG. 3, the amplitude of the voltage waveform output from the crank sensor decreases as the rotational speed of the crank rotor 11 decreases due to a decrease in the rotational speed of the output shaft of the engine. As a result, the voltage waveform easily crosses the threshold due to minute voltage fluctuations due to noise or the like. Therefore, if the voltage waveform crosses the threshold value due to such a minute voltage fluctuation, the crank sensor signal C is generated at a timing different from the actual state, and therefore the rotational speed of the engine output shaft cannot be calculated correctly. .

  Therefore, when the rotational speed of the output shaft of the engine is relatively low, the amplitude of the voltage waveform is kept constant by supplying current to the coil of the crank sensor in order to prevent the voltage waveform from crossing the threshold due to minute voltage fluctuations. There is a case where a measure for lifting by time P is taken (see the broken line in FIG. 3).

  The time for lifting the amplitude of the voltage waveform such as the fixed time P (amplitude lifting time) can be calculated based on the rotational speed of the output shaft of the engine. However, when the rotational speed of the output shaft of the engine is relatively low, if the amplitude lifting time is calculated based on the rotational speed of the engine output shaft, the calculated value may be incorrect. An example of this case will be described with reference to FIG.

FIG. 4 is a diagram illustrating an example of a method for calculating the amplitude lifting time based on the rotation speed of the output shaft of the engine. The rotational speed of the output shaft of the engine is equivalent to the input interval time of the crank sensor signal C. Therefore, this calculation method predicts the next input interval time T ₁ based on the average value of the two input interval times T ₋₁ and T ₀ immediately before the crank sensor signal, and according to the input interval time T ₁ . Calculate the amplitude lifting time for a given length.

However, in this calculation method, if the rotational speed of the crank rotor 11 is suddenly reduced due to a rapid decrease in the rotational speed of the output shaft of the engine immediately after the input interval time T ₀ has elapsed, the actual value as shown in FIG. input interval time T ₁ is expected much shorter than. Therefore, the amplitude lifting time shorter than the originally required length is calculated. That is, the amplitude lifting time cannot be calculated correctly.

  Therefore, an object of the present invention is to provide a rotational speed detection device that can correctly calculate the amplitude lifting time when the rotational speed of the output shaft of the engine is relatively low.

One idea is that
A crank rotor that rotates with the output shaft of the engine;
A crank sensor that outputs a voltage waveform whose amplitude decreases as the rotational speed of the crank rotor decreases;
A calculation unit that calculates a rotation speed of the output shaft based on the voltage waveform;
A motor having a rotating shaft coupled to the output shaft;
A resolver that detects a rotation angle position of the rotation shaft and outputs a detection signal according to the rotation angle position;
Based on the detection signal, a measurement unit that measures the rotational speed of the rotary shaft;
An amplification unit that raises the amplitude of the voltage waveform,
The calculation unit calculates a time for the amplification unit to increase the amplitude of the voltage waveform based on the rotation speed of the rotation shaft measured by the measurement unit when the rotation speed of the output shaft is equal to or lower than a predetermined speed. A rotational speed detection device is provided.

  Since the output shaft of the engine and the rotation shaft of the motor are connected, the rotation speed of the output shaft can be substituted with the rotation speed of the rotation shaft. Therefore, when the rotation speed of the output shaft is relatively low, even if the rotation speed of the output shaft cannot be used to calculate the amplitude lifting time of the voltage waveform, the voltage waveform The amplitude lifting time can be calculated correctly.

It is a figure which shows an example of the crank rotor rotated with the output shaft of an engine. It is a figure which shows an example of a voltage waveform when the rotational speed of a crank rotor is comparatively high. It is a figure which shows an example of a voltage waveform when the rotational speed of a crank rotor is comparatively low. It is a figure which shows an example of the method of estimating an amplitude raising period. It is a figure which shows an example of a structure of a rotational speed detection apparatus. It is a figure which shows an example of the flow of the process performed by the calculation part of a rotational speed detection apparatus. It is a timing chart which shows an example of the flow of processing performed by a calculation part. It is a timing chart which shows an example of an amplitude raising determination process.

  Hereinafter, an embodiment of a rotation speed detection device will be described with reference to the drawings. The “rotation speed” may be “the number of rotations per unit time” or “angular speed”. The unit of the number of rotations per unit time is, for example, [rpm (rotation per minute)], and the unit of angular velocity is, for example, [rad / s (radian per second)].

  FIG. 5 is a diagram illustrating an example of the configuration of the rotation speed detection device 1. The rotational speed detection device 1 is an example of a device that detects the rotational speed of the output shaft 14 of the engine 10. The rotational speed detection device 1 includes, for example, a crank rotor 11, a crank sensor 20, a control unit 30, a motor 50, a power split mechanism 40, a resolver 60, and a measurement unit 70.

  The crank rotor 11 is fixed to the output shaft 14 of the engine 10 and rotates together with the output shaft 14. For example, as shown in FIG. 1, the crank rotor 11 has a plurality of teeth 12 arranged at regular intervals, and a missing tooth portion 13 where the teeth 12 are not arranged. The missing tooth portion 13 represents a reference position (for example, 0 °) of the rotation angle position of the output shaft 14. The engine 10 is an example of an internal combustion engine that drives a vehicle by rotating an output shaft 14.

  The crank sensor 20 is an example of a rotation angle sensor that outputs a voltage waveform W whose amplitude decreases as the rotation speed of the crank rotor 11 decreases. The crank sensor 20 has a coil that detects a change in the magnetic field generated by the movement of the teeth 12 due to the rotation of the crank rotor 11 by a magnet pickup method, and generates a voltage waveform W corresponding to the change in the magnetic field detected by the coil. Output.

  The control unit 30 is an engine control device that executes engine control for rotating the output shaft 14 of the engine 10, and is, for example, an electronic control device (so-called ECU) including a calculation unit 32 and an amplification unit 33.

  The calculation unit 32 calculates the rotation speed of the output shaft 14 based on the voltage waveform W. For example, the calculation unit 32 detects a crank sensor signal that is input when the voltage waveform W crosses a predetermined threshold every cycle, and the rotational speed of the output shaft 14 of the engine 10 is determined from the input interval time of the crank sensor signal. Is calculated. The calculation unit 32 is, for example, a microcomputer including a central processing unit.

  The amplifying unit 33 increases the amplitude of the voltage waveform W when the rotation speed of the output shaft 14 is equal to or lower than a predetermined speed. For example, when the calculation unit 32 calculates that the rotation speed of the output shaft 14 is equal to or lower than the predetermined speed Vth, the amplification unit 33 supplies a current to the coil of the crank sensor 20 to increase the amplitude of the voltage waveform W. It is a supply circuit.

  The motor 50 has a rotating shaft 51 connected to the output shaft 14 via the power split mechanism 40. The motor 50 is, for example, a motor generator that functions as an electric motor that drives the vehicle by rotating the rotation shaft 51, while functioning as a generator driven by the vehicle wheel or the output shaft 14.

  The power split mechanism 40 is an example of a mechanism that divides or connects the output shaft 14 and the rotary shaft 51. When the output shaft 14 and the rotary shaft 51 are separated by the power split mechanism 40, the rotation of the output shaft 14 is not transmitted to the rotary shaft 51, and the output shaft 14 and the rotary shaft 51 are connected by the power split mechanism 40. If the output shaft 14 rotates, the rotation shaft 51 rotates as the output shaft 14 rotates.

  The resolver 60 detects a rotation angle position of the rotation shaft 51 of the motor 50 from 0 ° to 360 °, and outputs an analog detection signal corresponding to each rotation angle position.

  The measuring unit 70 measures the rotational speed of the rotating shaft 51 at a predetermined measurement cycle T by detecting a temporal change in the rotational angle position of the rotating shaft 51 based on, for example, a detection signal output from the resolver 60. Electronic control device (so-called ECU). For example, based on the detection signal output from the resolver 60, the measurement unit 70 calculates a digital value of the resolver rotation speed R [rpm], which is an example of the rotation speed of the rotating shaft 51, for a predetermined calculation period (that is, the measurement period T ). A specific example of the measuring unit 70 includes a motor control device that performs motor control for rotating the rotating shaft 51 of the motor 50.

  When the rotation speed of the output shaft 14 connected to the rotation shaft 51 via the power split mechanism 40 is equal to or lower than the predetermined speed Vth, the calculation unit 32 is based on the rotation speed of the rotation shaft 51 measured by the measurement unit 70. The time for the amplification unit 33 to raise the amplitude of the voltage waveform W is calculated.

  Since the output shaft 14 of the engine 10 and the rotation shaft 51 of the motor 50 are connected, the rotation speed of the output shaft 14 can be substituted with the rotation speed of the rotation shaft 51. Therefore, when the rotational speed of the output shaft 14 is equal to or lower than the predetermined speed Vth, the rotational speed detection device 1 does not require the rotational speed of the rotational shaft 51 even if the rotational speed of the output shaft 14 cannot be used for calculating the amplitude lifting time of the voltage waveform W. Based on the rotation speed, the amplitude lifting time of the voltage waveform W can be calculated correctly.

  For example, in the above-described calculation method shown in FIG. 4, since the amplitude lifting time shorter than the originally required length is calculated, the amplitude of the voltage waveform cannot be sufficiently raised to the originally required voltage. When the amplitude of the voltage waveform is not sufficiently raised as shown in FIG. 4, the voltage waveform may cross the threshold at a timing different from the original timing due to the back electromotive force generated in the coil of the crank sensor. If the voltage waveform crosses the threshold at a timing different from the original timing, the rotational speed of the engine output shaft cannot be correctly calculated from the input interval time of the crank sensor signal C.

On the other hand, the rotational speed detection device 1 of the present embodiment is configured so that the rotational speed of the crank rotor 11 suddenly decreases due to a rapid decrease in the rotational speed of the output shaft of the engine immediately after the input interval time T ₀ has elapsed. Based on the rotational speed of the rotating shaft 51, the amplitude lifting time of the voltage waveform W can be calculated correctly. As a result, the amplitude of the voltage waveform W can be sufficiently increased to a necessary voltage. Therefore, the voltage waveform can be prevented from crossing the threshold at a timing different from the original timing, and the rotation speed of the engine output shaft can be correctly calculated from the input interval time of the crank sensor signal C.

  FIG. 6 is a diagram illustrating an example of a flow of processing executed by the calculation unit 32 of the rotation speed detection device 1. FIG. 7 is a timing chart illustrating an example of the flow of processing executed by the calculation unit 32. Each process of FIG. 6 is demonstrated with reference to FIG.

  In step S <b> 10, the calculation unit 32 determines whether the current rotation speed of the output shaft 14 is in a high rotation area exceeding a predetermined speed Vth or in a low rotation area having a predetermined speed Vth or less. For example, the calculation unit 32 determines whether or not the current rotation speed of the output shaft 14 calculated based on the voltage waveform W is equal to or lower than a predetermined speed Vth.

  When the calculation unit 32 determines that the current rotation speed of the output shaft 14 is in a high rotation region exceeding the predetermined speed Vth, the calculation unit 32 increases the amplitude of the voltage waveform W (steps S20, S30, S40, and S50). ) Is not executed. On the other hand, when the calculation unit 32 determines that the current rotation speed of the output shaft 14 is in a low rotation region equal to or less than the predetermined speed Vth, the calculation unit 32 increases the amplitude of the voltage waveform W (steps S20, S30, S40). , S50).

  The calculation unit 32 is a resolver calculated in step S42, which will be described later, when the voltage waveform W crosses a predetermined threshold every cycle (that is, in step S20 when the crank sensor signal is input to the calculation unit 32). The rotational speed integrated value S is initialized at step S30. In the case of FIG. 7, the calculation unit 32 initializes the resolver rotation speed integrated value S at timings t1, t2, t3, and t6.

  After initialization of the resolver rotation speed integrated value S, the calculation unit 32 repeatedly executes the regular processing of step S40 in the order of steps S41, S42, and S43. For example, the calculation unit 32 executes the periodic process in step S40 with a timer mounted on the microcomputer.

  In step S <b> 41, the calculation unit 32 acquires the rotation speed of the rotation shaft 51 (for example, the digital value of the resolver rotation speed R [rpm]) from the measurement unit 70 at the measurement cycle T. The measurement period T is shorter than one period of the voltage waveform W.

  In step S <b> 42, the calculation unit 32 calculates the resolver rotation speed integrated value S based on the rotation speed of the rotation shaft 51 measured by the measurement unit 70 and the measurement cycle T. The resolver rotation speed integrated value S represents the angle at which the crank rotor 11 has rotated since the previous crank sensor signal was input to the calculation unit 32, and its unit is [CA (crank angle)].

  For example, according to the calculation formula described in step S42 in FIG. 6, the calculation unit 32 integrates the digital value of the resolver rotation speed R [rpm] acquired for each measurement cycle T for each measurement cycle T, thereby resolving the resolver. The rotational speed integrated value S can be calculated. In this calculation formula, the previous value indicates a value one measurement cycle T before the current value.

  Note that the rotation angle is calculated by adding the digital value of the rotation speed from the time when the previous crank sensor signal is input to the calculation unit 32. The rotation angle is calculated from the time when the previous crank sensor signal is input to the calculation unit 32. This is equivalent to calculating the rotation angle by integrating the analog value of the speed.

  In step S43, the calculation unit 32 determines whether or not the resolver rotation speed integrated value S calculated in the previous step S43 is within a rotation angle range (amplitude lifting angle range) corresponding to the amplitude lifting time of the voltage waveform W. To determine whether or not to perform amplitude lifting. When the resolver rotation speed integrated value S calculated in the immediately preceding step S43 is outside the amplitude increase angle range, the calculation unit 32 does not increase the amplitude of the voltage waveform W. On the other hand, the calculation unit 32 increases the amplitude of the voltage waveform W when the resolver rotation speed integrated value S calculated in the immediately preceding step S43 is within the amplitude increase angle range.

  FIG. 8 is a diagram illustrating an example of the amplitude lifting determination process in step S43. The amplitude lifting angle range is, for example, “S (Max) / 2 <S <S (Max) × 3/4”. S (Max) represents the rotation angle of one tooth of the crank rotor 11, and corresponds to 360/36 = 10 [CA] in the case of the crank rotor 11 having 36 teeth 12, for example.

  Therefore, the calculation unit 32 increases the amplitude of the voltage waveform W when “S (Max) / 2 <S <S (Max) × 3/4” is satisfied, so that the timing from timing t4 to timing t5 is satisfied. The amplitude of the voltage waveform W can be increased during the amplitude increase time. Timing t4 represents the time when a half cycle of the voltage waveform W has elapsed from timing t3 when the previous crank sensor signal was input to the calculation unit 32, and timing t5 represents the time when three quarters of the cycle has elapsed from timing t3. Thus, the calculation unit 32 can increase the amplitude of the voltage waveform W even at a timing shorter than one cycle of the voltage waveform W (that is, even when the crank sensor signal is interrupted).

  In step S50 in FIG. 6, the calculation unit 32 periodically executes the periodic process in step S40 until the next crank sensor signal is input. When the next crank sensor signal is input during the execution of the process of step S40, the calculation unit 32 interrupts the process of step S40 and starts again from the process of step S20.

  The rotation speed detection device has been described above by way of the embodiment, but the present invention is not limited to the above embodiment. Various modifications and improvements such as combinations and substitutions with some or all of the other embodiments are possible within the scope of the present invention.

  For example, the crank sensor signal may be input when the voltage waveform straddles the threshold value from the top to the bottom, or may be input when the voltage waveform straddles the threshold value from the bottom to the top.

DESCRIPTION OF SYMBOLS 1 Rotational speed detection apparatus 10 Engine 11 Crank rotor 14 Output shaft 20 Crank sensor 30 Control part 31 Estimation part 32 Calculation part 33 Amplification part 40 Power split mechanism 50 Motor 51 Rotation shaft 60 Resolver 70 Measurement part W Voltage waveform

Claims (1)

A crank rotor that rotates with the output shaft of the engine;
A crank sensor that outputs a voltage waveform whose amplitude decreases as the rotational speed of the crank rotor decreases;
A calculation unit that calculates a rotation speed of the output shaft based on the voltage waveform;
A motor having a rotating shaft coupled to the output shaft;
A resolver that detects a rotation angle position of the rotation shaft and outputs a detection signal according to the rotation angle position;
Based on the detection signal, a measurement unit that measures the rotational speed of the rotary shaft;
An amplification unit that raises the amplitude of the voltage waveform,
The calculation unit calculates a time for the amplification unit to increase the amplitude of the voltage waveform based on the rotation speed of the rotation shaft measured by the measurement unit when the rotation speed of the output shaft is equal to or lower than a predetermined speed. Rotation speed detection device.

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