JPS5875066A - Rotating speed detector - Google Patents

Abstract

PURPOSE:To obtain a high detection precision without electrical contact and without making the structure and the shape large-sized, by using a rotating plate and an electrode formed on this plate to detect the change of an electrostatic capacity. CONSTITUTION:When a shaft 150 is rotated to rotate a rotating plate 140 to a position where the first electrode 141 and the second electrode 142 face to the first electrode 121 and the second electrode 122 of a fixed plate 120, respectively, a signal having the same phase as a waveform 10 is transmitted as a signal 30 by a capacitor consisting of electrodes 121 and 141 and a capacitor consisting of a ring-shaped electrode 141' of the rotating plate 140 and ring-shaped electrode 131 of the fixed plate 130, and a signal 20 transmitted to the electrode 122 is transmitted as a signal 40, and a large current is flowed to the output terminal of a detecting circuit part. When the electrode 141 faces to the electrode 122, a small current is flowed to this output terminal. The rotation of the shaft is detected by the magnitude of this current.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotational speed detection device used in a vehicle speed sensor that detects the speed of a vehicle. The objective is to obtain high display accuracy without increasing the size of the shape.

To this end, the invention is characterized by the use of relatively rotating plates and a cleverly shaped electrode configuration thereon to detect changes in capacitance.

(2) The present invention will be described below with reference to embodiments shown in the drawings.

FIG. 1 shows the structure of the device of the present invention. A first fixing plate 120 made of an insulator on which electrodes are printed, a second fixing plate 130, and a circuit plate 260 on which a detection circuit 300 is arranged are arranged in a housing. The detection circuit 300 is fixed to the housing 100 with screws 240 through collars 210, 220, and 230.
Signal lines 250, 253 and 251°2 (not shown) from
52. 110 is a cover and is fixed to the housing 100 by a screw (not shown). The shaft A 150 and the shaft B 160 are bushes A that are driven into the housing 100 and clamp and fix the rotary plate 140 made of an insulator on which electrodes are printed.
170, and a bushing 8 that is driven into and fixed to the cover 110.
It is rotatable via 180. Bush A17
Nut part 200 and cover 110 rotatable through 0
The threaded part 110" provided on the vehicle transmission shaft 8160 can also be used as a replacement driven gear for the vehicle transmission.
is connected to the speedometer cable wire.

190 is a cord bushing that protects the lead wire from the detection circuit 300.

FIG. 2(A) is a view showing the surface of the first fixed plate 120 facing the rotating plate 130, and the signal lines 250, 251 are connected to the second fixed plate 13017, which will be described later.
) It is connected to connection portions 120 a and 120 b made of thin metal films through through holes 130 a and 130 b. Connection part 1
20a and 120b are first electrodes 121 made of metal thin films;
and a second electrode 122, and the electrodes are arranged alternately in the circumferential direction at predetermined intervals. 1st
A plurality of through holes 123 and 124 provided through the first fixing plate 12G allow each electrode 121° 122
are electrically connected by connecting thin metals 111121' and 122'.

FIGS. 2(C) and 2(D) show the rotary plate (4) 140, and (C) is the surface facing the first fixed plate 120, which rotates in circles alternately at predetermined intervals. Electrodes 141 and 142 made of thin metal films are arranged in the circumferential direction. (D) is +( from the metal thin film on the surface facing the second fixing plate 130, which will be described later).

The electrodes 142 and 1421 are electrically connected through a plurality of through holes 143 and 144 provided through the rotary plate 140.

FIGS. 2(E) and (F) show the second fixing plate 130 (
E) shows the surface facing the rotating plate 140. 131
, 132 are through-holes 133 and 134 penetrated by the metal thin film (a ring-shaped electrode, as shown in FIG. 2 (F), the second fixed plate) 130 and a metal thin film 11131 for connection. , 132'' to the connection parts 130c and 130d, and the signal line 2
It is connected to the detection circuit section 300 by 52.253.

FIG. 3 shows an electrical wiring diagram of the detection circuit section 300. 310 is a well-known OCR oscillation circuit (5), 320 is a reference signal generation circuit, and 330 is the electrodes 121, 122, 141, 142 of the first fixed plate 120, rotating plate 140, and second fixed plate 130.
．． 1411.142", 131.132, 340 is a comparison circuit, 350 is a phase detection circuit, 36
0 is an output circuit.

Terminal 301 is a power supply terminal and an output terminal. 302 is a ground terminal, 303 is a recacitor 37 from the ground terminal 302
0 to the housing.

Next, the operation of the above configuration will be explained.

In FIG. 3, inverter gates 311, 312, 313, resistors 314, 315,
The fifth
Obtain the oscillation waveform 1° shown in the figure (al).This oscillation waveform 1o
is transmitted to the reference signal generation circuit 320, where a signal having the same phase as the oscillation waveform lO and a signal 2o having the opposite phase as shown in FIG. 5(b) appear.

Here, as shown in Fig. 4 (al), the shaft is 150°1
60 (shown in Figure 1) causes the rotary plate (6) 140 to rotate so that its first electrode 14.1 is in a position opposite to the first electrode 121 of the first fixed plate 120, and the rotary plate A case will be described in which the second electrode 142 of the first fixed plate 140 is rotated to a position facing the second electrode 122 of the first fixed plate 120. A signal having the same phase as the oscillation waveform lO is transmitted to the first fixed plate 120 by the signal line 250.
When applied to the first electrode 121 of
and the first electrode 141 of the rotating plate 140 (331 in FIG. 3)
A signal having the same phase as the oscillation waveform 10 appears on the ring-shaped electrode 141' electrically connected to the first electrode 141 of the rotary plate 140 through the through hole 143, and the ring-shaped electrode 141' of the rotating plate 140 and the second A capacitor (332 in FIG. 3) consisting of a ring-shaped electrode 131 of a fixed plate 130
As a result, the fifth
The signal is transmitted as a signal 30 shown in FIG.

Similarly, the first fixing plate 12 is fixed by the signal cotton 251.
The signal 20 (7) transmitted to the second electrode 122 of the rotary plate 140 is connected to the capacitor (333 in FIG.
), the ring-shaped electrode 1 is electrically connected to the second electrode 142 of the rotating plate 140 via the through hole 144.
42' appears as a signal with the same phase as the signal 20, and a capacitor (334 in the iJ3 diagram) composed of the ring-shaped electrode 1421 of the rotating plate 140 and the ring-shaped electrode 132 of the second fixed plate 130 connects the connection part 130C. The signal is then transmitted to the comparison circuit 340 as a signal 40 shown in FIG. 5 (Td). However, the signals 30 and 40 have waveforms based on the voltage Va shown in FIG.

Now, the signals 30 and 40 are connected to an operational amplifier (hereinafter simply referred to as OP amplifier) 346 and a resistor 345 of the comparison circuit 340.
The waveform shown in FIG. 5 (81) delayed by the oscillation waveform 10 and the time ΔT appears as the signal 50. Here, the time Δ and T are the response delay of the capacitor ( 8) The signal 50 is the phase detection circuit 3.
The waveform shaped by the inverter gates 351 and 352 of 50 and having the same phase as the signal 50 is input to the clock terminal of the D type flip-flop 354, and the waveform of the signal 50
A waveform having a phase opposite to that of the D-type flip-flop 355 is input to the clock terminal of the D-type flip-flop 355.

Furthermore, a signal having the same phase as the oscillation waveform 10 is inputted from the CR oscillation circuit 310 to the data terminals of the D type flip-flops 354 and 355, and the output terminal QL of the D type flip-flop 354 is set to 0''. The output terminal Q of 355 becomes "1".Then, N
A signal ``1'' shown in FIG. 7(f) appears on the signal line 60 by the AND gates 356, 357, 35 and 8, 359. This signal is transmitted to the output circuit 360, the transistor 362 is turned on via the resistor 361, and a current 1t+I flows through the terminal 301.

In addition, as shown in FIG.
When the second electrode 142 of the rotating plate 140 faces the first electrode 121 of the first fixed plate 120, a signal having the same phase as the signal 20 appears at the first electrode 141 of the rotating plate 140, and as described above, Va is Signal 3 shown in FIG. 5 (0) as a reference
1 appears on the ring-shaped electrode 131 of the second fixed plate 130, and a signal with the same phase as the oscillation waveform lO appears on the second electrode 142 of the rotating plate 140, and a signal with the same phase as the oscillation waveform lO appears on the ring-shaped electrode 132 of the second fixed plate is the fifth value based on Va.
A signal 41 shown in figure (d) appears.

Then, at the output terminal of the comparator circuit 340, the signal shown in FIG.
) appears at the output terminal of the phase signal detection circuit 350, and the signal 61 shown in FIG. Current! , flows.

The first electrode 1 arranged on the rotating plate 140 in this way
41 and the second electrode 142 are driven into and fixed to the shirt) A150 and the shaft A (10).By the rotation of the shaft B160, the first fixing plate 1
When passing over the first electrode 121 and second electrode 122 installed at the terminal 301, the terminal 301
A current appears alternately, and by detecting the magnitude of this current by a detection circuit (not shown), the rotating plate 140
The rotation of the shaft A150 and the shaft B160 can be detected.

The housing 100 and cover 110 are connected to GND via a capacitor 370 to protect against noise and to prevent direct current from flowing between the body and the body ground.

In the above-described embodiment, the first and second electrodes arranged alternately in the circumferential direction are divided into eight parts as shown in FIG. 2, and a signal of eight pulses per revolution is obtained. The number of pulses per rotation may be increased or decreased by increasing or decreasing the number of electrode divisions. Also, the first and second
, the third and fourth electrodes do not have to completely coincide with the radial direction, but may have a certain inclination or curvature in the radial direction.

Further, in the embodiment, it is used as a vehicle speed sensor of a vehicle, but by changing the structure of the shaft portion, it may be used as a rotation detector for detecting the rotation speed of an industrial motor, etc., for example.

As described above, in the present invention, by increasing the number of divisions of the first to fourth electrodes arranged on the first fixed plate and the rotating plate, the number of pulses per rotation can be increased. This has the excellent effect of being able to detect the rotational speed with high accuracy and also being able to be miniaturized. Furthermore, by forming a capacitor between the rotating plate, the second fixed plate, and the second fixed plate to transmit signals, rotation can be detected without contact.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment in which the device of the present invention is applied to a vehicle speed sensor, and Fig. 2 is an explanatory view showing the electrode shape of each plate. top surface,
(C), (D) are the top and bottom surfaces of the rotating plate, (E),
(F) shows the upper and lower surfaces of the fixing plate in Fig. 2, Fig. 3 is a wiring diagram of the electric circuit, Fig. 4 is an operation explanatory diagram showing the positional relationship of each electrode and signal waveform, and Fig. 5 is a time chart of signals of each part for explaining the operation. 120...first fixed plate, 130...second fixed plate), 140...rotating plate), 150°1
60...Shaft, 121.122...1st. Second
electrode, 141.142...3rd. Fourth electrode. 141", 142'... 5th. 6th electrode, 131° 132. 4. 7th. 8th electrode, 300... detection circuit. Patent attorney Takashi Okabe (13) Figure 1 Figure 2 (C) (D) Figure 4 (a) td)" (b) Figure 5 0 Vaj" °1°・-

Claims (2)

[Claims] (1) It has a plurality of electrodes arranged radially at predetermined intervals, and the electrodes are electrically connected alternately. Second
a first fixed plate serving as an electrode; and a first fixed plate of the first fixed plate. The third electrode is arranged radially opposite to the second electrode. A fourth electrode is provided on one surface, and a concentric fifth electrode is provided on the other surface. a rotating plate having a sixth electrode, electrically connecting a third electrode and a fifth electrode, and electrically connecting a fourth electrode and a sixth electrode; No. 5 on the plate. A concentric seventh electrode facing the sixth electrode. a second fixed plate on which an eighth electrode is arranged; and the first. a mechanism for relatively rotating the rotating plate between the second fixed plates; and the first. A signal of a predetermined period is supplied to the second electrode in opposite phases to (1), and the supplied signal and the seventh. A rotational speed detection device comprising: means for detecting a phase state with a signal generated at an eighth electrode. (2) The rotating plate is driven and fixed between a shaft connected to the driven gear of the vehicle transmission and a shaft connected to the speedometer cable, and rotates with the rotation of the driven gear. A rotation speed detection device according to claim 1, wherein the rotation speed detection device is configured as follows.