JPS6367141B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a small and inexpensive speed detection device for a rotating machine that can obtain a voltage proportional to the rotation speed at a rotation angle of 360 degrees.

For most rotating machines used to control the rotation angle of various devices, such as stepping motors, which rotate less than 360 degrees, it is sufficient to detect the speed within the rotation angle. There is no need to use a conventional speed detection device such as a tachogenerator, that is, a large and expensive device for the purpose of detecting speed in 360° rotation. For this reason, various speed detection devices that meet the above requirements have been proposed, but these devices are complicated and expensive to manufacture, or have performance problems such as a narrow angle range for taking out voltage proportional to speed. It has its drawbacks and is not satisfactory.

Therefore, the present inventors have proposed a speed detection device based on the principle described below, which solves the above-mentioned drawbacks (see Japanese Patent Application No. 56-30524). This device is shown in Figure 1a.
As shown in the plan view shown in Fig. 1, a permanent magnet disk a is magnetized, for example, to the north pole at an angle corresponding to the required speed detection angle, and the remaining part is magnetized to the south pole.
As shown in the plan view and vertical cross-sectional view shown in Fig. 2, it is installed opposite to a fixed disk c having a generating coil b wound in a toroidal shape at one point, and is coaxially It is designed to rotate. In this device, the magnitude and polarity of the magnetic flux linked to the fixed generator coil b change in accordance with the magnetization angle and rotational speed (angular velocity) of the N and S poles of the permanent magnet disk a. Taking advantage of the fact that the strength of the magnetic flux in the magnetic part is constant, a voltage as shown in Figure 2 a and b is obtained from the generator coil b (Figure a shows the magnetization range of the N pole is 180°, b The diagram is
This is the case at 270°. ), the speed is detected by extracting a voltage proportional to the rotational speed within the magnetization angle range of the N pole, that is, the rotational angle of the speed-detected rotating machine, as shown by the shaded areas in Figure 2 a and b. . Therefore, by adjusting the magnetization angle of the N pole according to the rotation angle to be detected, it is theoretically possible to extract a speed signal within any desired rotation angle. However, in practice, it is impossible to wind the generator coil b so that it has no width, and it is impossible to avoid simultaneous interlinkage of the magnetic fluxes from the N and S poles of the permanent magnet disk a. . As a result, as shown in the waveform diagrams shown in Figure 2 a' and b', the waveform becomes dull at the exchange points from N to S and from S to N, so the range in which the voltage is proportional to the rotational speed is 180°. When the angle is 150°, and when the angle is 270°, it is about 240°, and it is not possible to extract a voltage proportional to the speed in a range of about 15° before and after. It is not possible to extract a voltage proportional to . Furthermore, since it is impossible in principle to eliminate the magnetization of the S pole, the maximum magnetization angle of the N pole must be 360° or less, and in practice it is around 330°. Therefore, if the rounding angle of the waveform is 15 degrees, the maximum rotation angle at which a voltage proportional to speed can be extracted is 315 degrees or less, and anything larger than that cannot be detected. Therefore, this device is more effective than conventional ones.
Although it is true that speed can be detected over a wide rotation angle range of 360° or less, it is still insufficient.

The present invention applies the speed detection principle described above to realize a small and inexpensive speed detection device that can extract a voltage proportional to the speed during 360° rotation. Explain.

FIGS. 3a and 3b are longitudinal cross-sectional views and circuit diagrams showing one embodiment of the device of the present invention, and FIGS. 4a and 4b are plan views of a permanent magnet rotating disk, a plan view of a fixed disk, and a permanent magnet rotating circle. It is a plan view showing the installation position of an element for detecting the magnetic pole of a plate, and its features are as follows. That is, first and second power generation coils are provided on a fixed disk at an angle of 180 degrees, and are formed so as to obtain first and second speed detection voltages with a phase difference of 180 degrees. A control signal generating circuit for selectively acquiring only a voltage portion proportional to the rotational speed over a range of 180 degrees from the first and second speed detection voltages in synchronization with the rotation of the plate, and the selective acquisition voltage thereof. The point is that a composite circuit is provided to extract a voltage proportional to the speed over the entire rotation angle of 360 degrees.

In FIG. 3, reference numeral 1 denotes a rotating shaft, which is supported by bearings 4 and 5 provided in parts 2 and 3 forming the case, and its protruding end is connected to a speed-detected rotary machine shaft (not shown). 6 is a donut-shaped permanent magnet rotating disk, for example, as shown in Figure 4a, the north pole is magnetized in an angular range of 270°, and the remaining 90° range is magnetized as a south pole; It is fixed to the rotating shaft 1 by a yoke disk 7 made of a high magnetic permeability material. 8 is a donut-shaped fixed disk made of high magnetic permeability material. 9 and 10 are the first
A second generating coil is wound in a toroidal manner at two points separated by an angle of 180 degrees on the fixed disk 8, as shown in FIG. 4b. The fixed disk 8 is fixed on the case portion 3 so as to coaxially face the permanent magnet rotating disk 6 with a small gap between them 11 and 12.
(12 is hidden and cannot be seen) are first and second magnetically sensitive elements that detect the magnetic poles of the permanent magnet rotating disk, and for example, a magnetically sensitive element such as a Hall element is used. If the magnetization angle of the N pole is 270° as described above with reference to FIG. 4a, then as shown in FIG. It is fixed on the case part 3 in close proximity to the permanent magnet rotating disk 6 so as to be located at a point of 45 degrees clockwise, and the installation angle is when the magnetization angle of the N pole is θ. , generally given by θ−180°/2. Also, in Figure 3, 13,
14 is a first and second phase detection circuit, 15 is a voltage selection and synthesis circuit, and the first and second phase detection circuit 1
The outputs of the magnetically sensitive elements 11 and 12 are added to 3 and 14, and the outputs are connected so as to be ANDed. The AND output is then applied to a voltage selection and synthesis circuit 15 to which the outputs of the first and second generator coils 9 and 10 are added. 16 is an output terminal for a voltage signal proportional to speed.

Next, the operation of this device will be explained with reference to the waveform diagram shown in FIG. The permanent magnet rotating disk 6 is the rotating shaft 1
Assume that it is rotated in the direction of arrow A in FIG. 4a. Then, according to the above _- described principle, the first generating coil 9 sends out a voltage E ₁ with the waveform shown in FIG. Different output voltages of E ₂
are sent out, and each of them is applied to the voltage selection and synthesis circuit 15. On the other hand, the first and second magnetically sensitive elements 11 and 12 are magnetized to the north pole in response to the magnetic flux from the permanent magnet rotating disk 6 within an angular range of 270 degrees, for example, with a positive polarity voltage S pole magnetization. In the angular range of 90 degrees, the voltage is converted to negative polarity and detected, but as described above, the first and second magnetically sensitive elements 11 and 12 are centered around the first generating coil 9.
They are set at points that have advanced 45 degrees and points that have delayed 45 degrees. Therefore, as shown in FIG. 5c, a voltage E ₃ is obtained from the first magnetic sensing element 11 in synchronization with the output voltage E ₁ of the first generating coil 9 and whose phase is 45° ahead of the output voltage E 1 .
Further, the second magnetically sensitive element 12 outputs a voltage _E4 shown in FIG. 5d, which is delayed by 45 degrees from _E1 . These E ₃ and E ₄ are the first and second phase detection circuits 13 and 14.
5 e, whose output becomes "1" when E ₃ and E ₄ have positive polarity, and "0" when they have negative polarity.
Phase detection outputs E ₃ ′ and E ₄ ′ of f are transmitted. These are ANDed to obtain the voltage selection acquisition control signal _{E 5} shown in FIG. It leads the output voltage E ₁ by 45°, and E ₄ ′ lags E ₁ by 45°.
Therefore, the AND output E ₅ becomes E ₁ as shown in Figure 5g.
The angular width formed by the high level and low level signals rises at a point 45 degrees later than that, falls at a point of 225 degrees and becomes zero, rises again at 405 degrees, falls at 585 degrees and becomes zero. are respectively 180° selective acquisition control signals. In this way, the AND circuit of the outputs of the magnetically sensitive elements 11 and 12 and the phase detection circuits 13 and 14 becomes a selection acquisition control signal generation circuit. Therefore, in the voltage selection and synthesis circuit 15, when the high level signal H is applied, the output _E1 of the first generating coil 9 is sampled, and when the low level signal L is applied, the output E1 of the first generating coil 9 is sampled.
If the output E ₂ of the generator coil 10 is sampled, the output E ₁ of the first generator coil 9 will be obtained as shown in FIG. 5h.
A voltage E A is obtained which is correctly proportional to the rotational speed between 45° and 225°, and a voltage E _A which is correctly proportional to the rotational speed between 225° and 405° is obtained at the output E ₂ of the second generating coil 10. _B is obtained. Thereafter, sampling operations are performed in the same manner, and a speed detection voltage signal _E6 that is correctly proportional to the rotational speed is obtained continuously over 360 degrees.

Therefore, according to the present invention, the first generator coil can be replaced with a simple structure by adding a second generator coil and an electronic processing circuit that can be formed sufficiently small according to current technology.
Like the one proposed by the present inventors shown in the figure, it is a small and inexpensive device that does not create a dead zone when detecting speed, and can also detect speed at a rotation angle of 360° in the same way as a conventional tachoze generator. A detection device can be provided. Furthermore, since the permanent magnet rotating disk 6 can be made lightweight, its inertia can be reduced compared to a conventional tachometer generator, and there is less risk of excessive control due to the large inertia of the speed-detected rotary machine.

The present invention has been described above with reference to an example in which the N pole of the permanent magnet rotating disk 6 is magnetized at an angle of 270 degrees and the rest is magnetized at S poles.However, theoretically, if the magnetization angle of the N pole is 180 degrees or more, , it is possible to obtain a voltage signal proportional to the speed over a 360° angle (the closer to 180°, the greater the output), but due to manufacturing accuracy and speed detection rotating machine described later. When consideration is given to eliminating the adverse effects of vibration, the magnetization angle of the N pole is preferably around 270°. Further, in the above description, the magnetization angle of the N pole was set to be 180° or more, but the angular widths of the N and S poles may be reversed.

In addition, in the detection device of the present invention, when the speed-detected rotating machine is one that easily generates vibrations such as a pulse motor, when the vibration occurs at the time of switching between the voltage signals E _A and E _B shown in Fig. 5h, the speed is detected. Voltage signal E ₆
generates noise voltage inside. For example E ₆
When attempting to perform feedback control of the speed of the pulse motor using the above-mentioned method, there is a risk that the control may be over-controlled and the control accuracy may be reduced. That is, since vibrations are transmitted to the permanent magnet rotating disk 6 through the rotating shaft 1, the output voltages E ₁ and E ₂ of the first and second generator coils 9 and 10 and the first and second phases are changed in response to the vibrations. Since the AND output E ₅ (selection acquisition control signal) of the detection circuits 13 and 14 also oscillates at its falling point, a noise voltage E _N is generated as shown by the dotted line in Fig. 5h, and as described above. This will result in significant drawbacks. However, this is because the first and second phase detection circuits 1
This can be prevented by providing the AND outputs of 3 and 14 with a hysteresis characteristic having an angular width greater than the vibration angular width, for example, a hysteresis characteristic of 10 degrees. For example, in the embodiment described above, the output voltage E ₁ of the first generator coil 9 is sampled between 45° and 225° when the rotating shaft 1 rotates in either the left or right direction.
The output voltage E ₂ of the second generating coil 10 between 225° and 405°
I tried to sample it. However, as shown in Figure 5g, by providing a hysteresis of 10°, the first
The output voltage E ₁ of the generator coil 9 is sampled, and the output voltage E ₂ of the second generator coil 10 is sampled between 230° and 410°, and during counterclockwise rotation, the output voltage E ₁ is sampled between 40° and 220°. By sampling E ₂ between 220° and 400°, the influence of pulse motor vibration can be removed.

Moreover, although an example in which a magnetically sensitive element is used as the selective acquisition control signal generating circuit element has been shown above, the present invention can also be implemented using a photosensitive element such as a phototransistor. In this method, for example, the diameter of the yoke disk 7 is set to the diameter of the permanent magnet rotating disk 6, as shown in the side view and plan view of the main parts shown in FIGS. Larger than that, the surrounding area
At the same time, the light source 18 and the photosensitive element 19 are provided facing each other so as to sandwich the notch 17 provided over a range of 180 degrees (without providing the notch 17, a corresponding mirror is provided, and the light source (The light from the magnetic field may be reflected and applied to the photosensitive element), and when the photosensitive element is installed at the same position as the magnetically sensitive element, and the magnetization angle of the N pole is set to, for example, 270 degrees, As shown in FIG. 6b, the coil is fixed at a point delayed by 45 degrees from the installation point of the first generating coil 9, and the same effect as using a magnetic sensing element is produced. That is, the permanent magnet rotating disk 6 is moved from the position shown in FIG. 6b.
When the light from the light source 18 reaches the photosensitive element 19 through the notch 17 by rotating in the direction of the arrow, the fifth
As shown in Figures a and g, the output of the photosensitive element changes from "1" to "0" at 180° intervals from a point delayed by 45° with respect to the output voltage E ₁ of the first generating coil 9. The signal E will be obtained as ₅ . Therefore, as shown in the circuit diagram shown in FIG. 7, this is added to the voltage selection and synthesis circuit 15, and the output voltage is
If E ₁ and E ₂ are sampled and synthesized, Figure 5 h
A voltage signal E ₆ proportional to the speed can be obtained over a rotation angle of 360° as shown in FIG. Therefore, according to this method, only one photodetection element is required and no phase detection circuit is required, so the speed detection device can be constructed more compactly and inexpensively than when a magnetically sensitive element is used.

As is clear from the above description, according to the present invention, it is possible to provide a speed detection device with a simple structure, small size, and low cost that can detect the rotation speed at a rotation angle of 360 degrees, and the practical effects are remarkable.

[Brief explanation of drawings]

Figures 1 a, b, and c are a plan view of a permanent magnet disk, a plan view, and a vertical sectional view of a fixed disk, showing a conventional speed detection device, and Figures 2 a, b, a', and b' are its operation. FIGS. 3a and 3b are a vertical cross-sectional view and a circuit diagram of a device showing an embodiment of the present invention, and FIG. 4 is a waveform diagram for explaining the
Figures a and b are a plan view of the permanent magnet fixed disk and a plan view of the fixed disk, Figure 5 is a waveform diagram of each part in the circuit diagram of Figure 3 b, and Figures 6 a and b are examples using photosensitive elements. FIG. 7 is a circuit diagram of the device shown in FIG. 6. DESCRIPTION OF SYMBOLS 1... Rotating shaft, 2, 3... Case part, 4, 5... Bearing, 6... Donut-shaped permanent magnet disk, 7... Yoke disk, 8... Donut-shaped fixed disk, 9, 10... First,
Second power generation coil, 11, 12...first and second magnetic pole position detection elements (magnetic sensitive elements), 13, 14...first,
Second phase detection circuit, 15... Voltage selection synthesis circuit, 1
6... Output terminal, 17... Notch, 18... Light source, 19
...Photosensitive element.

Claims (1)

[Claims] 1. A high magnetic permeability fixed disk on which first and second generating coils are wound in a toroidal shape at an angle of 180°, and a speed-detected rotating disk coaxially corresponding thereto. A permanent magnet rotating disk is rotated by a rotating shaft connected to the machine and magnetized with an angular range of 180° or more as N pole (or S pole) and the remaining angular range as S pole (or N pole). so that voltages having a phase difference of 180° are induced in the first and second power generation coils based on the interlinkage magnetic flux caused by the rotation of the permanent magnet rotating disk, and the first and second power generation coils A control signal generating circuit for selectively obtaining a voltage portion proportional to the rotation speed over an angular range of 180° from each output voltage of the
Speed detection of a rotating machine, characterized in that a circuit for synthesizing selectively obtained voltages from the output of the second generating coil is provided so that a signal proportional to the rotational speed of the rotating shaft can be obtained at a rotation angle of 360°. Device. 2 In the invention described in claim 1,
The control signal generation circuit is constituted by a combination circuit of voltages respectively induced in first and second magnetically sensitive elements fixed at a predetermined angle in front and behind the generator coil in close proximity to the permanent magnet rotating disk. A rotating machine speed detection device featuring: 3 In the invention described in claim 1,
The control signal generation circuit is fixed at a position delayed by a predetermined angle from the power generation coil, and is composed of a photosensitive element circuit configured to receive light only within that 180° angular range when the permanent magnet rotating disk rotates. A rotating machine speed detection device featuring: 4. The invention set forth in claim 1 is characterized in that the output of the control signal generation circuit has a hysteresis characteristic to avoid noise contamination due to vibration of the speed-detected rotating machine at the output voltage switching position. Speed detection device for rotating machines.