Signal generator for engine

Abstract

To facilitate setting for making a peak value of a pulse signal generated when a stator detects a first stage reluctor equal to the peak value of the pulse signal generated when the stator detects a second stage reluctor, in a signal generator for an engine having a stepped reluctor on a rotor side.SOLUTION: A signal generator for an engine includes a rotor 3 having a stepped reluctor 303 having a first stage reluctor 303A and a second stage reluctor 303B, and a stator 4 having a signal coil wound around a stator core having a magnetic pole section facing the reluctor at its tip. A portion deformed so as to play a role to suppress change in flux flowing through the stator core when the tip of the first stage reluctor 303A of the rotor 3 starts to face the magnetic pole section of the stator core 4a, is provided at a tip of the first stage reluctor 303A, and a peak value of a pulse signal generated when the stator 4 detects the first stage reluctor is limited to the peak value or less of the pulse signal generated when the second stage reluctor is detected.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an engine signal generator that generates a signal including crank angle information of an engine (internal combustion engine).

Background Art

[0002] In order to operate an engine, it is necessary to control the ignition timing and the fuel injection timing for each cylinder of the engine. In engine control, the timing for performing predetermined operations such as the ignition operation and the fuel injection operation is determined using the crank angle at the time of performing each operation. The crank angle is the rotation angle of the crankshaft measured with a specific position such as the position of the crankshaft when the piston of the engine reaches the top dead center (top dead center position) as the origin (0 degrees).

[0003] When controlling the ignition timing and the fuel injection timing of the engine, information on the crank angle of the engine is required. The crank angle information required when controlling the ignition timing and the fuel injection timing of the engine is, for example, information on the crank angle (usually 0 degrees) indicating the origin position set at or near the top dead center (TDC) of the piston of the engine, or the reference crank angle which is the crank angle giving the measurement start timing which is the timing for starting the measurement of the ignition timing and the fuel injection timing.

[0004] The engine signal generator outputs various signals necessary for engine control, such as a signal having crank angle information indicating the origin position of the crankshaft and a signal having reference crank angle information giving the timing for starting the measurement of the ignition timing and the fuel injection timing, in accordance with the rotation of the crankshaft of the engine. The engine control device obtains the crank angle information of the engine from the signals generated by the engine signal generator and controls the ignition timing and the fuel injection timing of the engine.

[0005] For example, when a control device for an engine controls the ignition operation of each cylinder of the engine, a signal generator detects the rotational speed of the engine from the interval at which a predetermined signal is generated, and using the crank angle when the piston of each cylinder reaches a position set to top dead center or the like as the origin position, the angle from the origin position to the crank angle that gives the ignition timing is defined as the ignition angle, and this ignition angle is calculated for various control conditions. The control device uses the crank angle that is more advanced than the most advanced ignition angle as the reference crank angle, and when it recognizes that the engine signal generator has generated a signal indicating the reference crank angle, it calculates the time required for the crankshaft to rotate from the reference crank angle to the ignition angle calculated at the rotational speed at that time, and sets the calculated time in a timer. The engine control device gives an ignition command to the ignition device to cause an ignition operation when the measurement of the time set in the timer is completed.

[0006] When the engine has a plurality of cylinders, it is necessary to control the ignition operation and fuel injection operation of the engine for each cylinder. Therefore, the signals generated by the engine signal generator include signals corresponding to each of the plurality of cylinders. Accordingly, when controlling the ignition operation and fuel injection operation of each cylinder of the engine, it is necessary to determine for which cylinder of the engine each signal generated by the signal generator is generated. Such determination performed on the signals generated by the signal generator is called cylinder discrimination.

[0007] As a signal generator for a multi-cylinder engine, as shown in Patent Document 1, there is widely used an inductor-type signal generator including a rotor yoke made of a ferromagnetic material and rotated together with the crankshaft of the engine, a rotor provided with a plurality of reluctor (inductors) respectively corresponding to a plurality of cylinders of the engine on the outer periphery of the rotor yoke, and a stator that generates a signal with a pulse waveform when each reluctor provided on the rotor is detected.

[0008] The stator has a stator core having a magnetic pole portion at its tip facing the surface where the rotor's reluctor is provided, a signal coil wound around the stator core, and a permanent magnet magnetically coupled to the stator core. When the reluctor of the rotor passes through the position of the magnetic pole portion at the tip of the stator core, it causes a change in the amount of magnetic flux flowing through the stator core, thereby inducing a pulse waveform signal in the signal coil.

[0009] In order to enable cylinder discrimination of signals, the signal generation device for an engine shown in Patent Document 1 is configured such that, among a plurality of reluctors provided on the rotor, one is a stepped reluctor having a stepped shape, and two cylinder discrimination pulses of the same polarity are continuously generated from the signal coil at a crank angle having a predetermined phase relationship with respect to a reference crank angle set at a position advanced from the origin position of the crankshaft.

[0010] If the signal generation device is configured as described above, since two pulse signals of the same polarity are continuously generated, it is possible to detect that a pulse signal for cylinder discrimination has been generated, and it is possible to determine that a pulse signal having a predetermined phase relationship with respect to any of the cylinder discrimination pulses is a signal generated at a reference crank angle set for a specific cylinder.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0012] If the signal generation device shown in Patent Document 1 is used, it is possible to perform cylinder discrimination of a signal including the rotation information of the crankshaft without separately providing cylinder discrimination means such as a camshaft sensor. When giving the pulse signal obtained from this type of signal generation device to an engine control device to control the engine, in order to prevent the engine control device from malfunctioning due to a noise signal, the pulse signal generated by the signal generation device is input to the engine control device through a signal input circuit having a function of removing noise.

[0013] The signal input circuit includes a capacitor in the input section that is charged by the input signal and generates a bias voltage at both ends. Among each part of the input signal, only the part exceeding the bias voltage is input to the engine control device as a signal including the rotation information of the engine. The capacitor that generates the bias voltage is charged by the pulse signal until the voltage value of the input pulse signal reaches the peak, and after the pulse signal reaches the peak, it is discharged through a discharge circuit with a certain time constant.

[0014] Referring to FIG. 10(A), an example of the shape of the stepped reluctor R' provided on the outer periphery of the rotor of the engine signal generation device is schematically shown. Referring to FIG. 10(B), an example of the waveforms of the pulse signals P1' and P2' induced in the signal coil wound around the stator core when the reluctor passes through the position of the magnetic pole portion (not shown) at the tip of the stator core is shown. FIG. 10(C) schematically shows an example of the waveform of the signal given from the signal input circuit to the engine control device.

[0015] The reluctor R' shown in FIG. 10(A) is provided so as to have a width dimension w1' and extend in an arc shape along the circumferential direction of the rotor, and has an arc-shaped first-stage reluctor Ra' with its tip Ra1' facing the front side in the rotation direction RD of the crankshaft, and a width dimension w2' larger than the width dimension w1' of the first-stage reluctor Ra'. It is provided so as to extend in the rotation direction of the crankshaft, with its tip Rb1' continuous with the rear end portion Ra2' of the first-stage reluctor Ra', and includes a second-stage reluctor Rb' with its rear end portion Rb2' facing the rear side in the rotation direction of the crankshaft.

[0016] In this signal generator, as the crankshaft rotates, when the tip Ra1' of the first-stage reluctor Ra' passes through the position of the magnetic pole portion of the stator core and when the tip Rb1' of the second-stage reluctor Rb' passes through the position of the magnetic pole portion of the stator core, the amount of magnetic flux flowing through the stator core changes in the same direction. Therefore, as shown in Fig. 10(B), when the tip of the first-stage reluctor passes through the position of the magnetic pole portion of the stator core and when the tip of the second-stage reluctor passes through the position of the magnetic pole portion of the stator core, pulse signals P1' and P2' of the same polarity are induced in the signal coil respectively. The peak values of the pulse signals P1' and P2' vary depending on the relationship between the width dimension of the first-stage reluctor Ra' and the width dimension of the second-stage reluctor Rb', the relationship between the width dimension of the magnetic pole portion at the tip of the stator core and the width dimension of the reluctor, etc.

[0017] In the example shown in Fig. 10(B), the peak value of the pulse signal P1' induced in the stator signal coil when the tip Ra1' of the first-stage reluctor Ra' of the rotor passes through the position of the magnetic pole portion at the tip of the stator core is higher than the peak value of the pulse signal P2' induced in the stator signal coil when the tip of the second-stage reluctor Rb' of the rotor passes through the position of the magnetic pole portion at the tip of the stator core. In Fig. 10(B), θ on the horizontal axis represents the crank angle.

[0018] To prevent the engine control device from malfunctioning due to noise, the signal shown in Fig. 10(B) is input to the engine control device through a signal input circuit provided with a capacitor in the input section that is charged by the input signal to generate a bias voltage. The capacitor that generates the bias voltage is charged by the input signal until the input signal reaches the peak, and is discharged at a constant time constant after the input signal has passed the peak. Therefore, as shown in Fig. 10(B), the waveform of the bias voltage Vb generated across the capacitor provided at the input section of the signal input circuit rises linearly during the period until the input signal reaches the peak, and then decreases at a constant slope after the input signal has passed the peak.

[0019] In the example shown in FIG. 10(B), while the pulse signal P1′ induced in the signal coil of the stator when the tip of the first-stage reluctor Ra′ of the rotor passes through the position of the magnetic pole portion at the tip of the stator core exceeds the bias voltage Vb, as shown in FIG. 10(C), a signal Q1′ is given to the engine control device, and the engine rotation information included in the signal P1′ is given to the engine control device.

[0020] On the other hand, since the pulse signal P2′ induced in the signal coil when the tip Rb1′ of the second-stage reluctor Rb′ of the rotor passes through the position of the magnetic pole portion of the stator core cannot exceed the bias voltage Vb, it is recognized as noise, and the engine rotation information included in the pulse signal P2′ is not given to the engine control device.

[0021] As described above, when the peak value of the pulse signal P1′ generated when the stator detects the first-stage reluctor is higher than the peak value of the pulse signal P2′ generated when the stator detects the second-stage reluctor, the engine rotation information included in the pulse signal P2′ generated when the second-stage reluctor is detected may not be given to the control device, so that the engine cannot be controlled accurately.

[0022] Patent Document 1 describes that by setting the width dimension W1′ of the first-stage reluctor Ra′ of the rotor to be smaller than the width dimension of the magnetic pole portion of the stator core and setting the width dimension W2′ of the second-stage reluctor Rb′ of the rotor to be larger than the width dimension of the magnetic pole portion of the stator core, the peak value of the pulse signal P1′ induced in the signal coil of the stator when the tip of the first-stage reluctor Ra′ of the rotor passes through the position of the magnetic pole portion at the tip of the stator core and the peak value of the pulse signal P2′ induced in the signal coil of the stator when the tip of the second-stage reluctor Rb′ of the rotor passes through the position of the magnetic pole portion at the tip of the stator core are made equal.

[0023] However, if set as described above, the width dimension W2' of the second-stage reluctor Rb' becomes large, causing the reluctor to become large-sized, and it may be difficult to adjust the balance of the rotor, which is not preferable. To prevent the reluctor from becoming large-sized, it may be considered to set the width dimension of the magnetic pole portion of the stator core to be small. However, if the width dimension of the magnetic pole portion of the stator core is set to be small, the width dimension of the first-stage reluctor becomes too small, resulting in a decrease in the strength of the first-stage reluctor, and there is a risk that the first-stage reluctor Ra' may be damaged when the rotor is attached to the engine, etc., which is not preferable.

[0024] An object of the present invention is to provide an engine signal generator that can prevent a situation where the wave height value of a pulse signal generated when the stator detects the first-stage reluctor is made less than or equal to the wave height value of a pulse signal generated when the stator detects the second-stage reluctor, without causing the reluctor with steps to become large-sized or the width dimension of the first-stage reluctor to become too small, resulting in a decrease in the strength of the reluctor, so as to prevent a situation where a signal generated later is not recognized by the engine control device.

Means for Solving the Problems

[0025] The present invention is applicable to a signal generating device for an engine, which includes a rotor that is provided to extend in the rotational direction of the crankshaft of the engine with a first width dimension and has a first-stage reluctor whose tip is directed forward in the rotational direction of the crankshaft, and a second-stage reluctor that is provided to extend in the rotational direction of the crankshaft with a second width dimension larger than the first width dimension and whose tip is integrated with the rear end of the first-stage reluctor, and is rotated together with the crankshaft of the engine; a stator core that has magnetic pole portions at its tip with which the first-stage reluctor and the second-stage reluctor of the rotor sequentially face each other during the rotation of the crankshaft of the engine, a signal coil wound around the stator core, and a permanent magnet that is magnetically coupled to the stator core and causes magnetic flux to flow through a magnetic path including the stator core and the reluctor of the rotor, and a stator that induces a first signal and a second signal of the same polarity in the signal coil due to changes in the magnetic flux that occur respectively when the tip of the first-stage reluctor starts to face the magnetic pole portion of the stator core and when the tip of the second-stage reluctor starts to face the magnetic pole portion of the stator core.

[0026] In the present invention, a deformed portion is provided at the tip of the first-stage reluctor of the rotor and / or at the magnetic pole portion of the stator core so as to function to suppress a change in the magnetic flux flowing through the stator core when the tip of the first-stage reluctor of the rotor starts to face the magnetic pole portion of the stator core, whereby the peak value of the first signal is limited to be equal to or less than the peak value of the second signal.

[0027] In one aspect of the present invention, a rounded portion is formed at the tip of the first-stage reluctor of the rotor, and this rounded portion constitutes the deformed portion.

[0028] The rotor of the signal generating device to which the present invention is applied may be manufactured by a method of forming a cup-shaped rotor yoke by performing press working on a plate made of a ferromagnetic material such as iron and then forming a reluctor by punching out a part of the peripheral wall portion of the rotor yoke outward in the radial direction, or may be manufactured by casting.

[0029] When manufacturing a rotor by a method of forming a rotor yoke by pressing and forming a reluctor by punching out a part of the peripheral wall of the rotor yoke radially outward, the rounded portion can be formed by performing an R chamfering process on the tip of the first-stage reluctor.

[0030] When manufacturing a rotor equipped with a reluctor by casting, since a portion having a rounded shape is inevitably formed at the tip of the first-stage reluctor, it is possible to provide a portion having a rounded shape at the tip of the first-stage reluctor without performing an R chamfering process on the tip of the first-stage reluctor.

[0031] In another aspect of the present invention, among the corners of the pole portion at the tip of the stator core, a rounded portion is formed at the portion where the tip of the first-stage reluctor first faces during the rotation of the rotor, and the rounded portion constitutes the deformed portion.

[0032] Also, when forming a rounded portion at the portion where the tip of the first-stage reluctor first faces during the rotation of the rotor among the corners of the pole portion at the tip of the stator core, a deformed portion having a rounded shape can also be provided at the tip of the first-stage reluctor of the rotor as needed.

[0033] The above rotor yoke may be provided exclusively for constituting the rotor of a signal generator, or may be provided for constituting the rotor of a generator attached to an engine or the like.

Effect of the Invention

[0034] In the present invention, a portion deformed so as to suppress a change occurring in the magnetic flux flowing through the stator core when the tip of the first-stage reluctor of the rotor starts facing the pole portion of the stator core is provided at the tip of the first-stage reluctor of the rotor and / or at the pole portion of the stator core. When the first-stage reluctor starts facing the pole portion of the stator core, the peak value of the first signal induced in the signal coil is limited to be equal to or less than the peak value of the second signal induced in the signal coil when the second-stage reluctor starts facing the pole portion of the stator core. Therefore, without causing the size of the second-stage reluctor of the stepped reluctor to increase and lead to an increase in the size of the reluctor, or without causing the width dimension of the first-stage reluctor to become too small and lead to a decrease in the strength of the first-stage reluctor, the peak value of the pulse signal generated when the stator detects the first-stage reluctor is made equal to or less than the peak value of the pulse signal generated when the stator detects the second-stage reluctor, preventing a situation where a signal generated later is not recognized by the engine control device.

Brief Description of the Drawings

[0035]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

[0036] Referring to FIG. 1, the configuration of an embodiment of a signal generator 1 for an engine according to the present invention is schematically shown. The illustrated signal generator 1 is composed of a rotor 3 attached to the crankshaft 2 of the engine and rotated together with the engine, and a stator 4. The stator 4 is attached to a stator mounting portion (not shown) provided on the engine case or a frame to which the engine is fixed, and is arranged in a state of being fixed to the engine case.

[0037] The rotor 3 includes a cup-shaped rotor yoke 301 attached to the crankshaft 2 of the engine. The rotor yoke 301 may be provided solely for constituting the rotor of the signal generator, or may be an accessory of the engine that is rotated together with the crankshaft 2, for example, a flywheel attached to the crankshaft of the engine, or a pulley attached to the crankshaft of the engine and connected to a fan for engine cooling via a belt.

[0038] In this embodiment, a flywheel attached to the crankshaft of the engine is used as the rotor yoke 301. The rotor yoke 301 may also serve as the rotor yoke of a magneto generator driven by the engine.

[0039] The illustrated rotor yoke 301 has a cup-shaped configuration integrally including a cylindrical peripheral wall portion 301a and a bottom wall portion 301b that closes one end side in the axial direction of the peripheral wall portion 301a. A boss portion 301c is formed at the center of the bottom wall portion 301b. By fitting the boss portion 301c onto the crankshaft 2 of the engine and keying it to the crankshaft, the rotor yoke 301 is attached to the crankshaft 2. The outer peripheral surface of the peripheral wall portion 301a of the rotor yoke 301 is a cylindrical surface 302 that shares the central axis with the crankshaft 2.

[0040] At least a portion near the outer periphery where the cylindrical surface 302 of the rotor 3 is formed is formed of a ferromagnetic material such as iron. On the portion formed of this ferromagnetic material, a first reluctor 303 and a second reluctor 304 that face the magnetic pole portions of the stator described later are formed.

[0041] In this embodiment, the engine has two cylinders, and the first reluctor 303 and the second reluctor 304 are provided corresponding to the first cylinder and the second cylinder of the engine, respectively. The first reluctor 303 and the second reluctor 304 are arranged at symmetric positions 180 degrees apart from each other.

[0042] Each reluctor is composed of arc-shaped protrusions extending in the circumferential direction of the rotor, and forms a closed magnetic circuit together with the stator core described later during the rotation of the rotor. Every time the rotation angle (crank angle) of the rotor 3 coincides with a set angle, a change is caused in the magnetic resistance of the closed magnetic circuit, thereby causing a change in the magnetic flux linked with the signal coil wound around the stator core, and outputting a signal including crank angle information from the signal coil. The structure of the stator will be described later.

[0043] In the example shown in FIG. 1, the entire rotor yoke 301 is formed of a ferromagnetic material such as iron. As shown in FIG. 2, the first reluctor 303 and the second reluctor 304 are formed on the cylindrical surface 302 of the rotor yoke 301. In the illustrated example, the reluctor 303 and 304 are formed at substantially the center of the width direction (the direction along the central axis of the rotor) of the cylindrical surface 302 of the rotor yoke. Note that the reluctor 303 and 304 do not necessarily have to be arranged at the center in the width direction of the cylindrical surface 302 of the rotor 3, and may be arranged offset to one side in the width direction of the cylindrical surface of the rotor 3.

[0044] The first reluctor 303 is a so-called stepped reluctor. As shown in FIGS. 3(A) and 3(B), the first reluctor 303 includes a first-stage reluctor 303A that extends in an arc shape in the circumferential direction of the rotor with a constant width dimension w1, and a second-stage reluctor 303B that extends in an arc shape in the circumferential direction of the rotor with a width dimension w2 larger than that of the first-stage reluctor 303A. The first-stage reluctor 303A and the second-stage reluctor 303B are provided in a state where the positions of the central portions in their respective width directions are aligned, with the tip 303A1 of the first-stage reluctor 303A facing the front side in the rotation direction RD of the rotor, and the tip 303B1 of the second-stage reluctor 303B being continuous with the rear end 303A2 of the first-stage reluctor 303A facing the rear side in the rotation direction RD of the rotor.

[0045] As shown in FIG. 2, the first-stage reluctor 303A and the second-stage reluctor 303B are positioned with their respective central portions in the width direction on the center line O extending in the circumferential direction of the rotor yoke, and are provided so as to be aligned in the circumferential direction of the rotor 3. Also, by giving the first-stage reluctor 303A and the second-stage reluctor 303B the same thickness dimension d, a step in the width direction (axial direction of the rotor) occurs at the boundary between the first-stage reluctor 303A and the second-stage reluctor 303B, but consideration is given so that no step occurs in the thickness direction (radial direction of the rotor). When manufacturing the rotor yoke by casting, when it is difficult to give the portions constituting the first-stage reluctor 303A and the portions constituting the second-stage reluctor 303B of the manufactured rotor yoke a uniform thickness dimension d, the portions constituting the first-stage reluctor 303A and the portions constituting the second-stage reluctor 303B are subjected to cutting, polishing, etc. to give both the same thickness dimension d, so that no step occurs in the thickness direction (radial direction of the rotor) at the boundary between the first-stage reluctor 303A and the second-stage reluctor 303B.

[0046] The second reluctor 304 is composed of a protrusion that extends in an arc shape in the circumferential direction of the rotor, having a width dimension W2 equal to the width dimension of the second-stage reluctor 303B of the first reluctor 304 and a thickness dimension equal to the thickness dimension d of the first reluctor 304.

[0047] The first reluctor 303 and the second reluctor 304 are arranged with the positions of the central portions in their respective width directions located on one circular center line O extending in the circumferential direction of the outer periphery of the rotor (in a state aligned in the circumferential direction of the rotor), and are arranged at symmetric positions with an angular interval of 180 degrees between them.

[0048] In the present embodiment, the rotation direction of the crankshaft 2 during the steady operation of the engine is defined as the positive rotation direction of the crankshaft 2. In FIG. 1, the positive rotation direction of the crankshaft is indicated by the arrow RD. Also, the direction along the central axis of the cylindrical surface 302 of the rotor 3 (the direction perpendicular to the paper surface of FIG. 1) is defined as the width direction of the cylindrical surface 302 and each reluctor.

[0049] Referring to FIGS. 5(A) and (B), an example of the configuration of the stator 4 that constitutes the engine signal generator 1 together with the above rotor is shown. The stator 4 includes a stator core 401 formed by laminating steel plates having a predetermined shape, a signal coil 402 wound around the stator core 401, a permanent magnet 403 that allows magnetic flux to flow through the stator core 401, and a magnetic path component 404 made of a ferromagnetic material such as iron. In the illustrated stator 4, the tip of the stator core 401 forms a magnetic pole portion 4a, and this magnetic pole portion 4a is opposed to the outer peripheral surfaces of the first reluctor 303 and the second reluctor 304 of the rotor with a gap therebetween.

[0050] The illustrated magnetic path component 404 includes a substrate portion 404a arranged in a state orthogonal to the radial direction of the rotor 3, and a side plate portion 404b that bends at a right angle from one end of the substrate portion 404a and extends toward the rotor 3 side. At the end of the side plate portion 404b near the substrate portion 404a, ear portions 404c, 404c protruding in opposite directions are formed, and mounting holes 404d, 404d are respectively formed in the ear portions 404c, 404c.

[0051] One magnetic pole (S pole in the illustrated example) of the permanent magnet 403 is coupled to the substrate portion 404a of the magnetic path component 404, and the rear end portion of the stator core 401 is coupled to the other magnetic pole (N pole in the illustrated example) of the permanent magnet 403.

[0052] The members constituting the stator 4 are coated with a molded portion made of insulating resin or housed in an appropriate case in a state where the magnetic pole portion 4a is exposed to the outside and at least a portion near the tip of the side plate portion 404b of the magnetic path forming member 404 and the ear portions 404c, 404c are exposed to the outside, and are arranged while maintaining a predetermined positional relationship.

[0053] The stator 4 is arranged in a state where the magnetic pole portion 4a at the tip of the stator core 401 is opposed to the region where the reluctor of the rotor 3 is formed with a gap therebetween, and the side plate portion 404b of the magnetic path forming member 404 is opposed to the portion where the reluctor of the rotor 3 is not provided with a gap therebetween. The ear portions 404c, 404c are fixed to a stator mounting portion (not shown) fixed to the engine case by bolts, whereby the stator 4 is attached to the engine.

[0054] In the present embodiment, the front end surface 404b1 of the side plate portion 404b of the magnetic path forming member 404 is opposed to the region where the reluctors 303, 304 near one end in the width direction of the cylindrical surface 302 of the rotor 3 are not formed, with an air gap therebetween. As a result, the magnetic path forming member 404 is magnetically coupled to the rotor yoke 301.

[0055] Note that the magnetic path forming member 404 may be magnetically coupled to the rotor 3 by opposing the tip of its side plate portion 404b to a portion near the outer periphery of the bottom wall portion 301b of the rotor 3, or may be magnetically coupled to the rotor 3 by being fixed to another appropriate member that is magnetically coupled to the rotor 3 with a gap therebetween.

[0056] In the illustrated engine signal generator 1, a magnetic path including a stator core and a rotor reluctance is formed between the rotor 3 and the stator 4, that is, a magnetic path consisting of a loop of permanent magnet 403 - stator core 401 - air gap - rotor 3 - air gap - magnetic path component 404 - permanent magnet 403. In the process of the rotation of the rotor 3, the reluctance changes the magnetic resistance of this magnetic path, thereby causing a change in the amount of magnetic flux flowing through the iron core and interlinking with the signal coil 402, and inducing a pulse signal in the signal coil 402.

[0057] Here, when the direction of the magnetic flux interlinking with the signal coil 402 changes in the increasing direction, the polarity of the pulse signal induced in the signal coil 402 is set as the positive polarity, and when the direction of the magnetic flux interlinking with the signal coil 402 changes in the decreasing direction, the polarity of the pulse signal induced in the signal coil 402 is set as the negative polarity. Then, the signal generator 1 shown in FIG. 1 outputs a series of pulse signals as shown in FIG. 6, for example, along with the change of the crank angle θ.

[0058] In FIG. 6, θ1 is the crank angle when the tip 303A1 of the first - stage reluctor (stepped reluctor) 303A of the first reluctor 303 starts to face the magnetic pole part 4a at the tip of the stator core 401, θ2 is the crank angle when the tip 303B1 of the second - stage reluctor 303B of the first reluctor 303 starts to face the magnetic pole part 4a at the tip of the stator core 401, θ3 is the crank angle when the rear end 303B2 of the second - stage reluctor 303B ends facing the magnetic pole part 4a at the tip of the stator core. Also, θ4 is the crank angle when the tip 304a of the second reluctor 304 starts to face the magnetic pole part 4a at the tip of the stator core, and θ5 is the crank angle when the rear end 304b of the second reluctor 304 ends facing the magnetic pole part 4a at the tip of the stator core.

[0059] When the tip of the first-stage reluctor 303A of the first reluctor 303 starts to face the magnetic pole portion 4a of the stator core at the crank angle θ1, the amount of magnetic flux flowing through the magnetic path increases, and the magnetic flux linking with the signal coil 402 increases. Therefore, a positive-polarity pulse signal P1 (first signal) is induced in the signal coil 402. When the tip 303B1 of the second-stage reluctor 303B of the first reluctor 303 starts to face the magnetic pole portion 4a of the stator core 401 at the crank angle θ2, the amount of magnetic flux flowing through the magnetic path increases again, and the amount of magnetic flux linking with the signal coil increases. Therefore, a positive-polarity pulse signal P2 (second signal) is induced in the signal coil 402. Also, when the rear end 303B2 of the second-stage reluctor 303B finishes facing the magnetic pole portion 4a of the stator core at the crank angle θ3, the magnetic flux flowing through the magnetic path decreases, and the amount of magnetic flux linking with the signal coil 402 decreases. Therefore, a negative-polarity pulse signal P3 (third signal) is induced in the signal coil.

[0060] When the rotor 1 further rotates and the crank angle θ reaches the crank angle θ4 and the tip 304a of the second reluctor 304 starts to face the magnetic pole portion 4a of the stator core, the amount of magnetic flux flowing through the stator core 401 increases, and the amount of magnetic flux linking with the signal coil 402 increases. Therefore, a positive-polarity pulse signal P4 (fourth signal) is induced in the signal coil 402. When the crank angle θ reaches the crank angle θ5, since the rear end 304b of the reluctor 304 finishes facing the magnetic pole portion of the stator core, the amount of magnetic flux flowing through the stator core decreases, and the magnetic flux linking with the signal coil 402 decreases. Therefore, a negative-polarity pulse signal P5 (fifth signal) is induced in the signal coil 402.

[0061] In a control device using the signal generation device as described above, in order to prevent malfunction due to noise, the signal output from the signal generation device is input to the microprocessor of the control device through a signal input circuit having a noise removal function. The signal input circuit includes a bias circuit including a capacitor charged by the signal input from the signal generation device and a resistor that discharges the charge of the capacitor with a constant time constant, and is configured to input only a pulse signal having a magnitude exceeding the bias voltage obtained at both ends of the capacitor to the control device.

[0062] Referring to FIG. 7, a configuration example of the apparatus is shown when the pulse signal output from the signal coil 402 of the stator is input to the engine control device through a signal input circuit provided with a bias circuit. In FIG. 7, 10 is a microprocessor provided in the engine control device, and 11 is a signal input circuit that inputs the pulse signal output from the signal coil 402 to ports A1 and A2 of the microprocessor 10.

[0063] The microprocessor 10 includes a CPU, a random access memory RAM, a read only memory ROM, a timer, etc., and performs various operations necessary for engine control using the information obtained from the pulse signal output from the signal coil 402.

[0064] The signal input circuit 11 includes NPN transistors TR1 and TR2 whose emitters are grounded and whose collectors are connected to ports A1 and A2 of the microprocessor respectively, a resistor R1 connected between the collector of the transistor TR1 and the output terminal of a power supply circuit (not shown) that outputs the power supply voltage Vc, a resistor R2 connected between the collector of the transistor TR2 and the output terminal of the power supply circuit (not shown), and a bias circuit provided between the signal coil 402 and the bases of the transistors TR1 and TR2.

[0065] The bias circuit includes diodes D1 and D2 whose cathodes are connected toward one end of the signal coil 402 between one end of the signal coil 402 and the ground potential portion and between the other end of the signal coil 402 and the ground potential portion, diodes D3 and D4 whose anodes are connected to one end and the other end of the signal coil 402 respectively, a capacitor C1 whose one end is connected to the cathode of the diode D3 and the other end is connected to the base of the transistor TR1 through a resistor R3, a capacitor C2 whose one end is connected to the cathode of the diode D4 and the other end is connected to the base of the transistor TR2 through a resistor R4, and resistors R5 and R6 connected in parallel to the capacitors C1 and C2 respectively.

[0066] In FIG. 7, when the signal coil 402 generates positive-polarity pulse signals P1, P2, and P4, current flows through the signal coil 402 - diode D3 - capacitor C1 - resistor R3 - the base-emitter circuit of transistor TR1 - diode D2 - signal coil 402. As a result, the transistor TR1 conducts and the potential of its collector decreases, and the potential of port A1 of the microprocessor 10 decreases. The microprocessor 10 recognizes that any one of the positive-polarity pulse signals P1, P2, and P4 has been generated when the potential of port A1 decreases. The transistor TR1 enters the cut-off state because the base current stops flowing when the charging of the bias capacitor C1 is completed.

[0067] When a base current flows through the transistor TR1, the bias capacitor C1 is charged with the polarity shown in the figure, so a bias voltage Vb is generated across its both ends, and the threshold value of the input circuit of the pulse signal increases. Thereafter, since the transistor TR1 conducts only when a positive-polarity pulse signal having a peak value exceeding the bias voltage Vb across both ends of the capacitor C1 is generated, only the pulse signal exceeding the bias voltage Vb is recognized as a normal pulse signal, and the pulse signal below the bias voltage Vb is excluded as a noise signal. The bias voltage Vb obtained across both ends of the capacitor C1 gradually decreases as the charge of the capacitor C1 discharges through the resistor R5.

[0068] When the signal coil 402 generates the negative-polarity pulse signals P3 and P5 shown in the figure, current flows through the signal coil 402 - diode D4 - capacitor C2 - resistor R4 - the base-emitter circuit of transistor TR2 - diode D1 - signal coil 402, causing the transistor TR2 to conduct and reducing the potential of port A2 of the microprocessor 10. The microprocessor recognizes that any one of the negative-polarity pulse signals P3 and P5 has been input by detecting the decrease in the potential of this port A2.

[0069] When the charging of the capacitor C2 in the bias circuit is completed, the base current of the transistor TR2 stops flowing, and thus it enters the cut-off state. Since the capacitor C2 is charged when the base current is flowing through the transistor TR2, a bias voltage Vb is generated across both ends of the capacitor C2. Thereafter, the transistor TR2 conducts only when a negative-polarity pulse signal having a peak value exceeding this bias voltage is generated. Therefore, only the negative-polarity pulse signal having a peak value exceeding the bias voltage is recognized by the microprocessor 10, and the negative-polarity pulse signal having a peak value below the bias voltage is excluded as a noise signal.

[0070] As described with reference to FIG. 10, when the peak value of the second signal P2' generated when the second-stage reluctor is detected is equal to or lower than the bias voltage Vb, the transistor TR2 cannot conduct. Therefore, the second signal P2' is excluded as noise, and the control device is not provided with the information carried by the second signal P2' generated when the stator detects the second-stage reluctor.

[0071] In order to prevent such a problem from occurring, as described above, Patent Document 1 proposes appropriately setting the relationship between the width dimension of the first-stage reluctor of the multi-stage reluctor and the width dimension of the magnetic pole portion of the stator core, and the relationship between the width dimension of the second-stage reluctor of the multi-stage reluctor and the width dimension of the magnetic pole portion of the stator core, so that the peak value of the pulse signal induced in the signal coil of the stator when the tip of the first-stage reluctor passes through the position of the magnetic pole portion at the tip of the stator core is made equal to the peak value of the pulse signal induced in the signal coil of the stator when the tip of the second-stage reluctor of the rotor passes through the position of the magnetic pole portion at the tip of the stator core. However, according to this proposal, there is a risk of problems such as the reluctor becoming larger in size, making it difficult to adjust the balance of the rotor, or the width dimension of the first-stage reluctor becoming too small, resulting in a decrease in the strength of the first-stage reluctor.

[0072] In order to prevent the occurrence of the above problems, in the present invention, a portion deformed so as to suppress a change occurring in the magnetic flux flowing through the stator core when the tip of the first-stage reluctor of the rotor starts to face the magnetic pole portion of the stator core is provided at the tip of the first-stage reluctor of the rotor and / or at the magnetic pole portion of the stator core, and the peak value of the first signal induced in the signal coil when the first-stage reluctor starts to face the magnetic pole portion of the stator core is limited to be equal to or less than the peak value of the second signal induced in the signal coil when the second-stage reluctor starts to face the magnetic pole portion of the stator core.

[0073] In the present embodiment, as shown in FIGS. 2, 3, and 4, a portion having a roundness is formed at the tip 303A1 of the first-stage reluctor 303A, and this portion having a roundness is used as the deformed portion.

[0074] As shown in FIGS. 3(A) and (B), the rounded portion may be provided such that the rounded shape is visible only when the tip 303A1 of the first-stage reluctor 303A is viewed along the radial direction of the rotor without changing the thickness d of the tip 303A1 of the first-stage reluctor. As shown in FIGS. 4(A) and (B), the rounded portion may be provided such that the rounded shape is visible only when the tip 303A1 of the first-stage reluctor 303A is viewed along the axial direction of the rotor without changing the width dimension of the tip 303A1 of the first-stage reluctor. Further, by combining the shape of the tip 303A1 of the first-stage reluctor shown in FIG. 3 and the shape of the tip 303A1 of the first-stage reluctor shown in FIG. 4, the tip 303A1 of the first-stage reluctor may be provided with a rounded shape such that the rounded shape is visible both when viewed along the radial direction of the rotor and when viewed along the axial direction of the rotor. As described above, when the rotor yoke is manufactured by casting and it is not possible to provide a uniform thickness to the portion constituting the first-stage reluctor and the portion constituting the second-stage reluctor on the outer periphery of the manufactured rotor yoke, grinding or polishing is performed on the portion that becomes the reluctor in order to give the first-stage reluctor 303A and the second-stage reluctor 303B the same thickness d. In this case, the rounded shape that is visible when the reluctor is viewed along the axial direction of the rotor and is naturally formed by casting may disappear depending on the degree of this processing.

[0075] The corner portion of the tip of the second-stage reluctor 303B is usually formed to have a shape without a rounded shape. However, when the width dimension of the stator core 401, particularly the magnetic pole portion 4a, is larger than the width dimension w2 of the second-stage reluctor 303B, the corner portion of the tip of the second-stage reluctor 303B may have a rounded shape. This is because the rounded portion is substantially located outside the magnetic path and the influence on the magnetic flux change becomes small.

[0076] As described above, if the tip 303A1 of the first-stage reluctor of the stepped reluctor is rounded, the amount of change in the magnetic flux flowing through the stator core can be suppressed when the tip 303A1 of the first-stage reluctor 303A begins to face the magnetic pole portion 4a at the tip of the stator core. Therefore, compared with the case where the tip 303A1 of the first-stage reluctor is not rounded, the peak value of the pulse signal (first signal) induced in the signal coil 402 when the tip 303A1 of the first-stage reluctor 303A passes through the position of the magnetic pole 4a at the tip of the stator core can be reduced.

[0077] Therefore, it is possible to prevent problems such as the width dimension of the second-stage reluctor 303B of the stepped reluctor becoming large and causing the reluctor to become large, or the width dimension of the first-stage reluctor 303A becoming too small and causing a decrease in the strength of the first-stage reluctor, and make the peak value of the pulse signal (first signal) generated when the stator detects the first-stage reluctor less than or equal to (preferably, equal to) the peak value of the pulse signal (second signal) generated when the stator detects the second-stage reluctor, thus preventing a situation where a later-generated signal is not recognized by the engine control device.

[0078] As a method of manufacturing a rotor having a reluctor on the outer periphery of a rotor yoke, a method of forming a cup-shaped rotor yoke by pressing a metal plate made of a ferromagnetic material and then forming a reluctor by punching a part of the peripheral wall of the rotor yoke from the inner side to the outer side in the radial direction, and a method of manufacturing a rotor having a reluctor on the outer periphery of the rotor yoke by casting can be considered.

[0079] In the case of the former method, after forming a reluctor by punching on the peripheral wall of the rotor yoke, an R chamfering process may be performed on the tip of the first-stage reluctor of the stepped reluctor. In this case, by simply adjusting the chamfering amount, it is possible to perform an adjustment to limit the peak value of the pulse signal generated when the tip of the first-stage reluctor passes through the position of the magnetic pole portion 4a of the stator core to be less than or equal to the peak value of the pulse signal generated when the tip of the second-stage reluctor passes through the position of the magnetic pole portion of the stator core.

[0080] In addition, when manufacturing a rotor having a reluctor on the outer periphery of the rotor yoke by casting, since a roundness is inevitably formed at the tip of the first-stage reluctor, it is possible to provide a portion deformed to have a roundness without performing an R chamfering process on the tip of the first-stage reluctor.

[0081] Referring to FIG. 8, a stepped reluctor to which the present invention is applied and waveforms of pulse signals induced in a signal coil by the stepped reluctor are shown. FIG. 8(A) is a developed view schematically showing the shape of the stepped reluctor. As already described, a portion having a roundness is formed at the tip 303A1 of the first-stage reluctor 303A.

[0082] FIG. 8(B) shows waveforms of pulse signals P1 and P2 induced in a signal coil wound around a stator core when the stepped reluctor 303 in FIG. 8(A) passes through the position of the magnetic pole portion at the tip of the stator core, and a waveform of a bias voltage Vb generated across the capacitor of the bias circuit when these pulse signals are input to an engine control device through a signal input circuit provided with the bias circuit.

[0083] When the present invention is applied to the stepped reluctance provided on the rotor, as shown in Fig. 8(B), the peak value of the pulse signal (first signal) P1 induced in the signal coil when the tip of the first-stage reluctance 303A of the stepped reluctance passes through the position of the magnetic pole portion 4a at the tip of the stator core, and the peak value of the pulse signal (second signal) P2 induced in the signal coil when the tip of the second-stage reluctance 303B passes through the position of the magnetic pole portion 4a at the tip of the stator core can be made substantially equal. Therefore, both the pulse signals P1 and P2 can exceed the bias voltage Vb. As shown in Fig. 8(C), the portions of the pulse signals P1 and P2 that exceed the bias voltage Vb can be input as signals Q1 and Q2 to ports A1 and A2 of the microprocessor of the engine control device. Accordingly, both the crank angle information of the pulse signal P1 and the crank angle information of the pulse signal P2 can be provided to the microprocessor, enabling the engine to be controlled without problems.

[0084] In the above embodiment, a portion deformed to have a rounded shape is provided at the tip of the first-stage reluctance of the stepped reluctance of the rotor of the signal generator. However, among the respective corner portions of the magnetic pole portion 4a at the tip of the stator core 401 facing the rear side in the rotation direction RD of the rotor, a portion having a rounded shape is formed in the portion facing the first-stage reluctance, and this portion having a rounded shape is made into a portion deformed so as to function to suppress the change in magnetic flux that occurs when the tip of the first-stage reluctance starts facing the magnetic pole portion at the tip of the stator core.

[0085] Figs. 9(A) and (B) show an example in which a portion is provided on the side of the pole portion 4a of the stator core 401, which is deformed so as to function to suppress a change in magnetic flux that occurs when the tip of the first-stage reluctor 303A starts to face the pole portion 4a at the tip of the stator core 401. In this example, among the respective portions of the corner portion 4a1 of the pole portion 4a at the tip of the stator core 401, a portion 401a having a rounded shape is formed in the portion where the tip of the first-stage reluctor first faces during the rotation of the rotor, and the portion having the rounded shape constitutes a portion that is deformed so as to function to suppress a change in magnetic flux that occurs when the tip of the first-stage reluctor starts to face the pole portion at the tip of the stator core.

[0086] As shown in Figs. 9(A) and (B), by providing a portion on the stator core side that is deformed so as to function to suppress a change in magnetic flux that occurs when the tip of the first-stage reluctor starts to face the pole portion at the tip of the stator core, it is also possible to make the peak value of the pulse signal generated when the stator detects the first-stage reluctor and the peak value of the pulse signal generated when the stator detects the second-stage reluctor equal in magnitude.

[0087] The present invention is not limited to the above-described embodiments, and by providing a portion deformed so as to have a rounded shape at both the tip of the first-stage reluctor and the tip of the pole portion of the stator core, it is possible to suppress a change in magnetic flux that occurs when the tip of the first-stage reluctor of the rotor starts to face the pole portion at the tip of the stator core, and to make the peak value of the first signal and the peak value of the second signal substantially equal in magnitude.

Explanation of Reference Numerals

[0088] 1 Signal generation device for engine 2 Crankshaft of engine 3 Rotor 301 Rotor yoke 301a Peripheral wall portion of rotor yoke 301b Bottom wall portion of rotor yoke 301c Boss portion of rotor yoke 302 Cylindrical surface on the outer periphery of rotor yoke 303 First Reluctor (Stepped Reluctor) 303A First-stage Reluctor 303A1 Tip of the First-stage Reluctor 303A2 Rear end of the First-stage Reluctor w1 Width dimension of the First-stage Reluctor 303B Second-stage Reluctor 303B1 Tip of the Second-stage Reluctor 303B2 Rear end of the Second-stage Reluctor w2 Width dimension of the Second-stage Reluctor d Thickness dimension of the First-stage Reluctor and the Second-stage Reluctor 304 Second Reluctor 304a Tip of the Second Reluctor 304b Rear end of the Second Reluctor O Center line RD Rotation direction of Rotor 3 4 Stator 401 Stator core 402 Signal coil 403 Permanent magnet 404 Magnetic circuit component 404a Substrate part of the Magnetic circuit component 404b Side plate part of the Magnetic circuit component 404c Ear part 404d Mounting hole 4a Magnetic pole part at the tip of the Stator core

Claims

1. A first-stage reluctor provided with a first width dimension and extending in the rotational direction of the crankshaft of the engine, with its tip directed forward in the rotational direction of the crankshaft, and a second-stage reluctor provided with a second width dimension larger than the first width dimension and extending in the rotational direction of the crankshaft, with its tip integrated with the rear end of the first-stage reluctor. A rotor having a reluctor on the outer periphery of the rotor yoke and being rotated together with the crankshaft, a stator core having magnetic pole portions at its tip that are sequentially opposed to the first-stage reluctor and the second-stage reluctor of the rotor during the rotation of the crankshaft of the engine, a signal coil wound around the stator core, and a permanent magnet magnetically coupled to the stator core and passing magnetic flux through a magnetic path including the stator core and the reluctor of the rotor. When the tip of the first-stage reluctor starts to face the magnetic pole portion of the stator core and when the tip of the second-stage reluctor starts to face the magnetic pole portion of the stator core, a stator that induces a first signal and a second signal of the same polarity in the signal coil due to the changes in the magnetic flux respectively. An engine signal generation device, An engine signal generation device, wherein a deformed portion is provided at the tip of the first-stage reluctor of the rotor and / or at the magnetic pole portion of the stator core, which functions to suppress the change in the magnetic flux that occurs when the tip of the first-stage reluctor of the rotor starts to face the magnetic pole portion at the tip of the stator core, and the peak value of the first signal is limited to be equal to or less than the peak value of the second signal.

2. The engine signal generation device according to claim 1, wherein a rounded portion is formed at the tip of the first-stage reluctor of the rotor, and the rounded portion constitutes the deformed portion.

3. The engine signal generation device according to claim 1, wherein a rounded portion is formed at a portion of the corner of the magnetic pole portion at the tip of the stator core, which is the first portion that the tip of the first-stage reluctor faces during the rotation of the rotor, and the rounded portion constitutes the deformed portion.

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