JP2008197027A - Antenna device for engine tachometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To supply a tachometer body with high-level pulses having engine speed information on a prescribed level by eliminating variations in reception sensitivity depending on the cable length while preventing the entry of external noise. <P>SOLUTION: This antenna device is provided with: a wave receiving plate 11 for receiving an electromagnetic wave arising from an engine ignition system; a pulse input circuit part 21 for guiding the electromagnetic wave received by the receiving plate 11 to an induction coil 14 to take it therein as a pulse component of a prescribed frequency and level; and a waveform shaping circuit part 22 for waveform-shaping the pulse taken in the circuit part 21 to output it to the tachometer body via a cable 1 and a plug 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an antenna device for an engine tachometer that inductively receives electromagnetic waves generated in an ignition system of an engine and measures an engine speed based on a pulse obtained by the induction reception.

  In general, an engine ignition device uses a power generation coil provided in association with an engine drive system such as a camshaft, and the capacitor is charged with a high voltage current induced by the power generation coil, and then determined by an ignition control device. The spark plug is discharged at a predetermined timing.

  On the other hand, the engine speed may be measured using an engine tachometer for engine performance confirmation and inspection. In this case, if the distance from the generation site of electromagnetic waves from the engine to the engine rotation speed detection site, that is, the engine tachometer is increased, the loss of electromagnetic wave energy is greatly reduced. The number cannot be detected and measured accurately.

  In view of the above circumstances, the present applicant, an engine tachometer that can measure the engine speed while reducing the loss of electromagnetic waves, even when the distance from the generation site of the electromagnetic waves from the engine and the engine tachometer is long, For example, it is proposed in Patent Document 1.

  The engine tachometer has an electromagnetic wave receiving part that is used close to a site where electromagnetic waves from the engine are generated, and an antenna lead connected to the electromagnetic wave receiving part. The electromagnetic wave is taken in.

According to the antenna device of the engine tachometer, the electromagnetic wave generated from the vicinity of the ignition plug of the engine is received by a dedicated electromagnetic wave receiving unit, and the electromagnetic wave is converted into a high level electric signal, and the engine tachometer is passed through the antenna lead. It can be sent directly to the rotational speed calculation unit etc. in a low loss state.
JP 2006-262032 A

  However, in the conventional engine tachometer, although the antenna lead can be used to directly guide the current based on the electromagnetic wave to the engine tachometer while suppressing the energy loss of the received electromagnetic wave, the antenna lead As a result, the reception level of electromagnetic waves obtained by the engine tachometer, that is, the reception sensitivity varies. In addition, intrusion of external noise into the antenna lead cannot be avoided, and therefore an error may occur in the measured value of the engine speed by the engine tachometer.

  The present invention has been made paying attention to the conventional problems as described above, and incorporates the pulse obtained at the receiving portion of the electromagnetic wave generated from the engine into the cable end connected to the tachometer body. By providing an antenna unit that gives the waveform shaping function, the tachometer can be supplied with a pulse at a predetermined level that does not affect the reception sensitivity due to the cable length and can avoid the intrusion of external noise. An object is to provide an antenna device for a tachometer.

  In order to achieve the above object, an antenna device for an engine tachometer according to the present invention guides an electromagnetic wave generated by an ignition system of an engine to a receiving plate, and receives the electromagnetic wave received by the receiving plate in an induction coil. A pulse input circuit unit for taking out as a pulse of frequency and level, and a waveform shaping circuit unit for outputting waveform shaping of the pulse extracted by the pulse input circuit unit to the tachometer main body through a cable and a plug. It is characterized by.

  With the above configuration, electromagnetic waves generated in the ignition system of the engine received by the wave receiving plate can be supplied as a high-level pulse from one end side to the other end side of the cable without being affected by the length or routing of the cable. Therefore, the measurement accuracy of the engine speed by the engine tachometer can be improved.

  The antenna device for an engine tachometer according to the present invention is characterized in that the wave receiving plate, the pulse input circuit portion, and the waveform shaping circuit portion are resin-molded and housed in one case.

  With the above configuration, the case is brought into contact with or in contact with the measurement site for measuring electromagnetic waves, so that only the electromagnetic waves generated from the measurement site are not affected by external noise and are passed through the cable to the tachometer main body side. In addition to being able to send out, the antenna part can be made compact and circuit components in the antenna part can be protected.

  The antenna device for an engine tachometer according to the present invention is characterized in that the cable has a shielded cable structure in which an electromagnetic shielding member covers the periphery of a lead wire that outputs the pulse from the waveform shaping circuit unit. To do.

  With the above configuration, it is possible to efficiently guide the pulse from the antenna unit obtained from the electromagnetic wave to the engine tachometer without being affected by the external noise while reliably preventing the external noise from entering the lead wire.

  An antenna device for an engine tachometer according to the present invention includes: an induction coil provided in the tachometer body through the signal output plug constituting the plug unit and the output of the waveform shaping circuit unit in the plug unit; A dummy circuit switching plug for bypassing the signal and inputting the rotation number to the rotational speed calculation circuit section is provided in parallel with the signal output plug.

  With the above-described configuration, a pulse corresponding to the engine speed that has been subjected to signal processing different from the electromagnetic wave from the conventional antenna device side that does not have the wave receiving plate, the pulse input circuit unit, and the waveform shaping circuit unit is provided to the tachometer body. , Can be selectively input to the tachometer main body to measure the rotational speed with high accuracy and reliability.

  According to the present invention, the electromagnetic wave received by the wave receiving plate is guided to the electromagnetic induction coil, and is constituted by a pulse input circuit unit that extracts the pulse component as a pulse component, and a waveform shaping circuit unit that shapes the extracted pulse. The electromagnetic wave generated in the ignition system of the engine received by the wave receiving plate can be supplied as a high-sensitivity pulse from one end of the cable to the other end without being affected by the length of the cable. The measurement accuracy of the engine speed can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an antenna device of an engine tachometer according to an embodiment of the present invention, FIG. 2 is a front view showing the antenna device of the engine tachometer, and FIG. 3 shows the antenna device of the engine tachometer. FIG. 4 is a block connection diagram showing a circuit configuration of the antenna unit. The engine tachometer antenna apparatus shown in the drawings includes a cable 1, an antenna unit 2, and a plug unit 3. The antenna unit 2 is connected to one end of the cable 1, and the plug unit 3 is connected to the other end. .

  The cable 1 is provided with a signal output lead wire that has been subjected to electromagnetic shielding processing (shield processing). The cable 1 is configured as a flexible cable or a rigid cable for convenience of handling and use.

  The antenna unit 2 includes a wave receiving plate 11 in which a conductive plate such as a copper material is formed in a circular shape or other shapes, a circuit board 13 installed on a side surface of the wave receiving plate 11 via a spacer 12, and a circuit board. 13 is provided with an electromagnetic wave induction coil 14 connected and fixed on a circuit on 13. This circuit includes a pulse input circuit section and a waveform shaping circuit section described later.

  Conductive pins 15 that transmit electromagnetic waves received by the wave receiving plate 11 to the coil 14 through the central portion of the circuit board 13 are provided at the center of the wave receiving plate 11. The circuit board 13 is connected to each power line 16, signal line 17, and ground line 18 in the cable 1.

  The wave receiving plate 11, the spacer 12, the circuit board 13, the coil 14, the conductive pin 15 and the three lead wires 16, 17, 18 are accommodated in an insulating case 19 fixed to the end of the cable 1. The resin is molded with an insulating resin filled in the case 19. As a result, the electronic circuits in the antenna unit 2 can be integrated in a compact manner and the durability can be improved mechanically, electrically, and chemically.

  Further, a cover plate 20 made of an insulating material is fitted into the opening end of the case 19, and the resin mold body covered with the cover plate 20 can be isolated from the external environment, so that an internal electronic circuit is provided. Furthermore, it is fully protected.

  In the embodiment, the wave receiving plate 11 is made of, for example, a conductive metal disk so that when the wave receiving plate 11 is brought close to an electromagnetic wave generation source of an engine ignition system, the electromagnetic wave is concentratedly received within a wide surface of the disk. Function. The coil 14 functions to guide the electromagnetic wave received by the wave receiving plate 11 through the conductive pin 15.

  As shown in FIG. 4, the circuit board 13 in the antenna unit 2 includes a pulse input circuit unit 21 that takes in a pulse of a predetermined frequency and level from the electromagnetic wave induced in the coil 14, and a waveform shaping circuit unit that shapes the pulse. (Both not shown) 22 is provided.

  The power supply line 16 supplies a power supply voltage to the pulse input circuit unit 21, the waveform shaping circuit unit 22, and the like. The signal line 17 supplies the waveform-shaped pulse to the signal output plug 3 a of the plug unit 3. The ground line 18 holds a ground potential.

  The plug portion 3 has a dummy circuit switching plug 3b arranged in parallel with a certain distance from the signal output plug 3a. The signal output plug 3a and the circuit switching plug 3b can be inserted into each one signal input jack and circuit switching jack (both not shown) provided in the tachometer body (not shown).

  On the other hand, the circuit switching plug 3b is smaller in diameter and shorter than the signal output plug 3a and is not used for signal input / output. That is, the circuit switching plug 3b simply acts to mechanically switch the circuit connected to the jack on the tachometer body side.

  Therefore, when the plugs 3a and 3b are simultaneously inserted into the one jack, the waveform shaping circuit section in the antenna section 2 is bypassed by bypassing an electromagnetic wave induction coil (not shown) in the tachometer body. The pulse input from 22 can be switched and input. On the other hand, when a conventional plug having a simple structure in which an antenna lead is connected to the wave receiving plate is inserted into a signal input jack of the tachometer body, the conventional plug is used by the electromagnetic induction coil in the tachometer body. The electromagnetic wave from is induced and converted into a pulse in the main body of the tachometer.

  In the engine tachometer antenna device configured as described above, the signal output plug 3a and the circuit switching plug 3b constituting the plug portion 3 are inserted into each one of the jacks provided on the tachometer body side. Thus, the jack switch circuit on the tachometer body side is switched by the circuit switching plug 3b, and the pulse from the signal output plug 3a does not pass through the electromagnetic induction coil provided on the tachometer body side. It can be taken into the tachometer body.

  Therefore, following the insertion of the plugs 3a and 3b into the respective jacks, the antenna unit 2 is brought close to or in contact with an electromagnetic wave generation site of the engine. As a result, only the electromagnetic wave from the electromagnetic wave generation site is intensively taken into the wave receiving plate 11 and further guided to the electromagnetic wave induction coil 14 of the pulse input circuit unit 21 to be converted into a pulse having a predetermined frequency and level. . In the antenna unit 2, the waveform shaping circuit unit 22 performs waveform shaping of the pulse so as to be suitable for rotation speed calculation by an engine tachometer, and outputs the waveform to the signal output plug 3a.

  In the above case, the electromagnetic wave generated at or near the measurement site can be intensively received by bringing the antenna unit 2 close to or in contact with the measurement site of the electromagnetic wave. The pulse processed by the antenna unit 2 can be supplied to the tachometer body via the cable 1, the signal output plug 3a, and a signal input jack (not shown) in sequence. For this reason, even if there is a difference in cable length, the pulse is not affected by external noise and can be accurately measured as engine speed information.

  Further, by providing the cable 1 with a shield structure that avoids the disturbance of external noise, the cable 1 can be freely routed and the invasion of external noise can be avoided.

  Furthermore, when the cable 1 is made flexible, the ease of handling and operability at the time of electromagnetic wave measurement is improved, and the distance and position between the engine body and the measurer (operator) can be arbitrarily selected. Measurement work can be performed safely.

  On the other hand, when the cable 1 has a certain degree of hardness, it is possible to measure the engine speed in a state in which the antenna unit 2 is in contact with or in contact with the portion to be measured together with the tachometer body. Become.

  Further, the receiving plate 11, the pulse input circuit unit 21, and the waveform shaping circuit unit 22 constituting the antenna unit 2 are resin molded and housed in one case 19, so that the other than the antenna unit 2 Intrusion of extraneous noise and electrical, mechanical, and chemical external influences can be avoided, and a pulse having only information on the engine speed can be input to the tachometer body with high sensitivity.

  Further, the pulse after waveform shaping by the waveform shaping circuit unit 22 passes through the signal output plug 3a constituting the plug unit 3 and bypasses an induction coil (not shown) provided on the tachometer body side. Thus, the dummy type circuit switching plug 3b for inputting to the rotational speed arithmetic circuit section (not shown) is provided in parallel with the signal output plug 3a, thereby switching the jack on the tachometer main body side. Information on the engine speed can be supplied to the engine speed calculation circuit section on the engine speed side by automatically performing the bypass operation of the induction coil prepared for the conventional antenna device.

  As described above, the antenna device of the engine tachometer of this embodiment guides the electromagnetic wave received by the wave receiving plate 11 to the induction coil 14 and the wave receiving plate 11 that receives the electromagnetic wave generated by the engine ignition device. , A pulse input circuit unit 21 to be extracted as a pulse component of a predetermined frequency and level, and a waveform shaping circuit unit 22 which shapes the pulse extracted by the pulse input circuit unit and outputs it to the main body of the tachometer through the cable and plug. Are provided so that a pulse based on electromagnetic waves generated in the ignition system of the engine received by the wave receiving plate 11 is not affected by the length of the cable 1 and the routed state, and the other end side from the cable 1 side. Therefore, the measurement accuracy of the engine speed by the engine tachometer can be improved.

  The antenna device of the engine tachometer of the present invention can supply electromagnetic waves generated in the ignition system of the engine as a pulse with high sensitivity from one end of the cable to the other end without being affected by the length of the cable. An engine tachometer antenna that has the effect of improving the accuracy of measurement of the engine speed by the engine tachometer and measures the engine speed based on pulses obtained by induction reception of electromagnetic waves generated in the ignition system. Useful for devices and the like.

It is a perspective view which shows the antenna apparatus of the engine tachometer by embodiment of this invention. It is a front view of the antenna apparatus of the engine tachometer shown in FIG. It is sectional drawing of the principal part in the antenna apparatus of the engine tachometer shown in FIG. It is a block connection diagram which shows the circuit structure of an antenna part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cable 2 Antenna part 3 Plug part 3a Signal output plug 3b Circuit switching plug 11 Wave receiving board 13 Circuit board 14 Electromagnetic wave induction coil 19 Case 20 Cover plate 21 Pulse input circuit part 22 Waveform shaping circuit part

Claims (4)

A wave receiving plate that receives electromagnetic waves generated in the ignition system of the engine, a pulse input circuit that guides the electromagnetic waves received by the wave receiving plate to an induction coil and extracts the pulses as a predetermined frequency and level, and the pulse input circuit An antenna device for an engine tachometer, comprising: a waveform shaping circuit unit that shapes the extracted pulse and outputs the waveform to a tachometer body through a cable and a plug. The antenna device for an engine tachometer according to claim 1, wherein the wave receiving plate, the pulse input circuit unit, and the waveform shaping circuit unit are molded into a resin and housed in one case. 2. The engine tachometer antenna device according to claim 1, wherein the cable has a shielded cable structure in which a lead wire that outputs the pulse from the waveform shaping circuit unit is covered with an electromagnetic shielding member. In the plug section, the output of the waveform shaping circuit section passes through a signal output plug constituting the plug section and bypasses the induction coil provided in the tachometer body to the rotation speed calculation circuit section. The antenna device for an engine tachometer according to claim 1, wherein dummy circuit switching plugs for input are arranged in parallel to the signal output plugs.

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