Time totaling meter for internal combustion engines

Description

[0001] This invention relates to a time totaling meter which can be used for maintenance and repair of working machines driven by an internal combustion engine such as chain saws, weed cutters and the like.

[0002] Heretofore, working machines such as chain saws and weed cutters driven by an internal combustion engine have not been installed with a time totaling meter or equivalent such as is being used for maintenance and repair of a four-wheeled vehicle, a motor bicycle and the like. Therefore, for said working machines or internal combustion engines, a cumulative operated time cannot be determined.

[0003] Maintenance and repair of said working machines and internal combustion engines are being made at an interval and frequency decided by its user or not being made at all. Consequently, there were several problems, due to inadequate maintenance and repair of said working machines and internal combustion engines; they cannot be used due to unexpected trouble, or broken parts causes accident involving human life, for example.

[0004] On the other hand, an attachable/detachable type of time totaling meter, which will be used attached to a working machine itself, was proposed e.g. in JP-U-24110/1992 in order to avoid inadequate or incomplete maintenance and repair as mentioned above. According to this proposal, total time from initiation of operation of working machines and internal combustion engines can be counted and stored in a memory and further can be displayed.

[0005] Such attachable/detachable type of time totaling meter may be intentionally or unintentionally removed from said working machines by their users. Therefore, in case such time totaling meter was detached and again attached to the working machine, total operation time of the working machine without the time totaling meter is not added to the actual cumulative operation time of the working machine, and therefore counted, stored and displayed cumulative operation time does not reflect the actual cumulative operation time of said working machines and internal combustion engine from their initial operation. This is a problem for the attachable/detachable type of time totaling meter.

[0006] US 5029188 describes an actuation counter for counting the number of operation cycles of a valve or other electrically actuated device. The device includes a series of external access jacks.

[0007] Patent Abstracts of Japan vol. 010, no. 198 (P-476), 11 July 1986 (1986-07-11) and JP 61040534 A (Tokyo Tatsuno Co. Ltd.), 26 February 1986 (1986-02-26) describes a device that comprises an antenna coil for detecting electromagnetic waves emitted by the spark of an ignition plug near to which the device is located.

[0008] EP 0319422 describes an hour meter which displays the number of hours of operation of an internal combustion engine near which it is located. The independent claim is characterised over this document.

[0009] US 4999820 describes an hour meter which is activated by stray magnetic flux leaking from a piece of equipment near to which it is located.

[0010] CH 672960 describes a wire antenna that detects if an electric fence is live near to which the operator is located.

[0011] According to the present invention, there is provided a time totaling meter as claimed in claim 1.

[0012] The preferred time totaling meter for internal combustion engines is capable of accurately counting, storing and displaying only total time during which an internal combustion engine of a working machine has been operated, allowing to do appropriate maintenance and repair of said working machine and internal combustion engine based on data of said cumulative operation time, and capable of being constructed simply and at low cost.

[0013] The time totaling meter is preferably capable of displaying total operation time of an internal combustion engine based on its revolution number by picking up electromagnetic wave from a high tension cable into an induction coil via an antenna lead and also capable of realizing treatment of said antenna lead in a small occupation space.

[0014] In a preferred time totaling meter for internal combustion engines, the end of the cables to be connected to the unit block can be housed inside the time totaling meter having pre-determined thickness. Because the connected part of the end of the cables does not significantly protrude toward the outside, the space occupied by this connecting part can be minimized, thereby package size for the time totaling meter can be compacted. Preferably the unit comprises a case to house the waveform shaping circuit, count memory means and display means together with the induction coil, wherein one corner of the case has different surface level from the upper and lower surfaces of other parts of the case so as to have pre-determined thickness, and several holes are provided so as to pass through said thinner part from the upper surface to the lower surface and an antenna lead can be inserted into the holes by bending the end part thereof.

[0015] In a preferred time totaling meter for internal combustion engines, ignition pulses supplied to an ignition plug can be electromagnetically detected by an induction coil via the high tension cable and the antenna lead and, by counting detected output pulses after waveform shaping, total operation time of the internal combustion engine can be simply and accurately measured.

[0016] Further, the end of said antenna lead can be coupled to said pulse treatment circuit containing said waveform shaping means inside of said thinner part formed on one corner of the case, thereby the space occupied by this connection part can be minimized and therefore the package size for the time totaling meter can be reduced.

[0017] A preferred embodiment of the present invention together with other arrangements given for illustrative purposes only will now be described by way of example only and with reference to the accompanying drawings in which:

Fig. 1 is a block diagram showing a time totaling meter for internal combustion engines;

Fig. 2 is an outside view as well as partial inside view showing detail construction of a time totaling meter for internal combustion engines;

Fig. 3 is a circuit diagram showing the connection relationship between a time totaling meter and an ignition circuit for internal combustion engines;

Fig. 4 is an outside view showing a chain saw provided with a time totaling meter for internal combustion engines;

Fig. 5 is a block diagram showing another time totaling meter for internal combustion engines;

Fig. 6 is a diagram showing connecting structure of a time totaling meter for internal combustion engines;

Fig. 7 is an outside view showing a time totaling unit for internal combustion engines;

Fig. 8 is an outside view showing a time totaling unit for internal combustion engines;

Fig. 9 is an outside view showing a preferred connecting embodiment of a time totaling meter according to the present invention;

Fig. 10 is an outside view showing another connecting example of a time totaling meter.

[0018] Fig. 1 is a block diagram showing a whole time totaling meter. In this arrangement numeral 1 is a time totaling meter and 2 is a remaining part of an ignition device connected to this time totaling meter 1. This time totaling meter l includes a part of the ignition device 3 connected to the remaining part of the ignition device 2.

[0019] In the time totaling meter 1, numeral 4 is pulse induction means comprising a printed electromagnetic induction coil, for example, and located near to a part of the ignition device 3 so as to have induced and to detect ignition pulses flowing in this part of the ignition device 3. Numeral 5 is waveform shaping means to shape the waveform of output pulses induced.

[0020] The waveform shaping means can be constituted, for example, so as to be able to clip the ignition pulses obtained by the pulse induction means 4 at a pre-determined level and then to convert this clipped pulse to a rectangular pulse having a constant time length by a monostable multivibrator (not shown in the drawings).

[0021] Further, numeral 6 is judging means to distinguish whether said waveform shaped output could be obtained or not; that is, whether the internal combustion engine is actually operated (working) or not. Internal combustion engines generate the same shaped pulse (having the same time length) at constant intervals, while all other pulses have different peak height and time length even after waveform shaping. Therefore the judging means can distinguish the pulses actually derived from the operating internal combustion engine, based on continuity in a unit time of the same shaped pulse output from the waveform shaping means. 7 is count memory means to count and store surely and accurately total operation time from the initial operation (from the first operation) of the internal combustion engine based on normal waveform shaped output selected by this judging means 6.

[0022] Numeral 8 is display means such as a liquid-crystal display to display counted results by said count memory means 7. 9 is a pulse treatment circuit comprising said waveform shaping means 5, judging means 6 and count memory means 7.

[0023] Fig. 2 is an outside view and partial inside view showing detail construction of a time totaling meter 1. In this drawing, a diode 10 comprising a part of the ignition device 3 is provided on the same printed wiring board 11 together with pulse induction means 4 and said pulse treatment circuit 9. However, as part of the ignition device 3 it is not always necessary to include the diode 10.

[0024] As shown in Fig. 2, the block of the pulse treatment circuit 9 is provided with said display means 8. 12 is a case of the time totaling meter 1 to house the part of said ignition device 3, pulse induction means 4, pulse treatment circuit 9, printed wiring board 11 and the like. An attachment piece 12b of this case 12 is provided with a screw hole 14 to insert an attachment screw 13. 12a is a window for the display means 8.

[0025] Numerals 15 and 15 are cables attached to both ends of the diode 10 comprising a part of said ignition device 3. 16 and 16 are two connectors attached to each cable 15 as connecting terminals. These connectors 16 are provided so as to be attachable or detachable to two connectors (detailed later) provided in the remaining part 2 in the ignition device.

[0026] Fig. 3 is a circuit showing detail of an arrangement for an ignition device for internal combustion engines. In this drawing, numeral 21 is a rotor having a magnet or magnetic poles and rotating synchronously with rotation of the internal combustion engine. 22 is an induction coil to induce voltage according to the approach and departure of said magnet by rotation of the rotor 21.

[0027] Further, 23, 24 and 25 are rectifier diodes, and 26 is a resistor to set an electric potential to trigger a gate of a thyristor (detailed later). 27 is a charge/discharge capacitor for ignition and 28 is an ignition coil serially connected via the charge/discharge capacitor 27 and the diode 10 which consists of said part 3 of the ignition device. This ignition coil 28 consists of a primary coil 28a and a secondary coil 28b and an ignition plug 29 is connected to the secondary coil 28b.

[0028] Further, 30 is the thyristor which is serially connected to the charge/discharge capacitor 27 and then to the primary coil 28a of the ignition coil 28 via said resistor 26. The gate of the thyristor 30 is connected to the resistor 26 via the diode 24.

[0029] Numerals 31 and 31 are a pair of cables provided so as to disconnect the circuit introducing induced voltage to the charge/discharge capacitor 27, and the end of each cable is provided with a connector 32 as a connecting terminal. And, each of these connectors 32 is attachable to each connector 16 in said time totaling meter 1 by one touch.

[0030] In this case, because the diode 10 consisting of a part of the ignition device 3 is directional, each of the connectors 32 must be properly connected to each of the connectors 16.

[0031] Therefore, it is desirable to form one connector as male and another as female, for example.

[0032] Furthermore, the remaining part of the ignition device as mentioned above is placed inside a chain saw 40 together with said internal combustion engine and said time totaling meter 1 is provided on the chain saw 40 in a freely attachable and detachable manner as shown in Fig.4, for example.

[0033] This chain saw 40 is provided with a saw chain 42 which can be rotated around a saw chain guide plate 41 by driving force of said internal combustion engine. On the other hand, the case 12 of said time totaling meter 1 is attached on the chain saw 40 near to a handle 43 by attaching screws 13 through screw holes 14 in a manner so as to be attachable and detachable. 44 is a halt switch which is provided on the chain saw 40 near to the handle 43 and used to bring to halt operation of the ignition circuit when it is turned on.

[0034] Next, the operation of the time totaling meter and the unit of the same according to an arrangement will be explained. When the internal combustion engine is fired and the rotor 21 starts rotating, magneto coil 22 generates induced voltage by 13 magnetic flux of the magnet provided on the rotor 21. Then, said charge/discharge capacitor 27 for ignition is charged by this voltage supplied via said diode 10 consisting of a part of the ignition device.

[0035] When the terminal voltage of said resistor 26 reaches the predetermined voltage, said thyristor 30 is turned on to supply the voltage of the charge/discharge capacitor 27 to the primary coil 28a of the ignition coil 28. Therefore, high voltage is induced at the secondary coil, and the ignition plug generates spark to fire a mixed gas containing fuel and air so that the internal combustion engine is continuously operated.

[0036] On the other hand, in the operation of such internal combustion engines, induced voltage of several hundreds volts is introduced into the charge/discharge capacitor 27 as well as into the part 3 of the circuit; that is, into the time totaling meter 1 having the diode 10 as the part 3 of the ignition device.

[0037] Therefore, ignition pulses are detected by said pulse induction means 4 during their passage through the diode 10 and then the waveform thereof is shaped by the waveform shaping means 5. Output of this shaped waveform is input into the judging means 6. This judging means 6 determines whether output signals from the waveform shaping means are obtained every unit time or not; that is, whether said pulses are those generated by operation of the internal combustion engine or not.

[0038] When said ignition pulses are determined that they were generated by operation of the internal combustion engine, the count memory means 7 count and store total operation time from the initial operation of the internal combustion engine (from the first operation of a working machine) based on the result thereof. Then, the total count obtained is displayed by the display means. Voltage induced by the magneto coil was used in this embodiment; voltage generated by the secondary coil 28b of the ignition coil, which has a larger electromagnetic induction effect, may be used.

[0039] On the other hand, to bring the internal combustion engine to a halt, said halt switch 44 is turned on. Thereby the magneto coil 22 is shorted, and charging of the charge/discharge capacitor 27 as well as supply of ignition pulses to said diode 10 are brought to a halt.

[0040] Consequently, the operation of the internal combustion engine is brought to a halt and total operation time of the internal combustion engine from start of operation is stored in the count memory means 7. The total operation time can be displayed always or as necessary.

[0041] Meantime, when the total operation time displayed on the display means 8 of the time totaling meter 1 exceeds 200 hours, the user can perform maintenance to check loosening of bolts and nuts, decreased power due to time lag of ignition, increase of exhaust gas and the like. Thus, safety and efficient operation of internal combustion engines and working machines can be realized afterward.

[0042] Furthermore, said time totaling meter 1 can be removed from working machines such as the chain saw 40 as shown in Fig. 4 to prevent theft and to avoid mischief by children.

[0043] Thus, at the same time when the time totaling meter is removed from the working machine, the diode 10 is also removed from the remaining part 2 of the ignition device. Therefore, charging of the charge/discharge capacitor 27 by induced voltage is inhibited so that the internal combustion engine cannot be operated. At the same time, the time totaling meter 1 is also brought to a halt.

[0044] That is, to operate the internal combustion engine (to use the working machine), the time totaling meter 1 must be attached to the working machine. Specifically, to operate the internal combustion engine, each of the connectors 16 shown in Fig. 3 is connected to corresponding connector 31 so that operation time afterward is accurately and automatically added to the actual total operation from the initial operation and this total value can be displayed on the display means 8.

[0045] In the embodiment described above, the time totaling meter 1 is attached onto an appropriate position of the main body of the chain saw 40 using attaching screw 13 and the like.

[0046] Alternatively, another structure in which the time totaling meter 1 is attached or detached by one touch or is screwed in may be used.

[0047] In the time totaling meter of the arrangement aforementioned, the diode 10 is mounted on the same printed wiring board 11 on which the pulse induction means 4 and the pulse treatment circuit 9 have been mounted. Thereby, the size and weight of the time totaling meter itself can be minimized. It is needless to say that separate printed wiring boards may be used due to reason of design.

[0048] In addition, although the ignition device having the condenser discharge type ignition circuit was shown in Fig. 3, the same can be applied to other types of ignition device having a circuit breaker type ignition circuit using a thyristor and power transistor for switching.

[0049] In this circuit breaker type ignition circuit, the primary short-circuit current induced in the ignition coil is introduced to the power transistor and then shorted at the pre-determined timing for example. Thereby, reverse electromotive force is generated at the primary side of the ignition coil and high voltage at the secondary side, then it can be output to the ignition plug.

[0050] Fig. 5 shows another arrangement. Different from the time totaling meter for internal combustion engines aforementioned, in this arrangement, the first count memory means 7A reliably and accurately count and store total operation time from the initial operation. Further, the second count memory means 7B reliably and accurately count and store total operation time from the arbitrary time point set by the user by manipulating re-setting means 50. According to this method, each count and stored value can be displayed by display means 8 by choice. Other operations and effects are the same as those obtained by the previous embodiment.

[0051] Fig. 6 shows a connecting diagram of a time totaling meter. This time totaling meter comprises a magneto coil 22, an ignition coil 28 and an ignition 17 device formed as a unit block B by aforementioned one-body molding. In this arrangement, a time totaling meter 1 is also molded in one-body. 61 is a magnet core coiled with the magneto coil 22 in the unit block 3. 65 is a cable to be connected to a halt switch, and 66 is a high tension cable to be connected to a plug cap.

[0052] That is, the ignition device in the unit block B is connected to a part 3 of the ignition device in the time totaling meter 1 placed outside the unit block 3 via cables 68 and 68, Further, in this time totaling meter 1, various cumulative pulse treatment circuits shown in Fig. 1 are provided.

[0053] This arrangement is more effective in case one-body molding of the time totaling meter 1 and the ignition device is not appropriate; in case operation and reliability of the time totaling meter are impaired due to effects of heat or noises generated by said ignition device or in case it is necessary to realize highly sensitive integration of sufficient level of ignition pulses directly picked up.

[0054] It is not necessary to say that the ignition device may be constructed as a condenser discharge type having a trigger coil to generate circuit breaker signals or may be constructed as a circuit breaker type having a power transistor to short the primary current of an ignition coil by switching a thyristor by output of the trigger coil or by the primary voltage of the ignition coil.

[0055] That is, a part or whole of the circuit breaker type or condenser discharge type ignition circuit can be formed in one-body as said unit block 3 and then attached to said working machine in a manner freely attachable and detachable, combined with the time totaling meter or independently.

[0056] Fig. 7 shows the structure of another time totaling unit for internal combustion engines. In this arrangement, the magneto coil 22, the ignition coil 28 and other parts of the ignition circuit are formed as one-body together with the time totaling meter 1 by injection molding of thermoplastic resin or built-in molding of thermoplastic resin so as to form one unit block B.

[0057] Therefore, this unit block 3 is assembled with the magnet core 61 having said magneto coil 22 as shown in Fig. 7. The rotor 21 provided with multiple magnets 64 along its peripheral surface at pre-determined intervals is provided near two magnetic poles 62 and 63 of this magnet core 61 so as to freely rotate. This rotor 21 synchronously rotates by driving force from a driving shaft of the internal combustion engine. Thereby, voltage of pulse form is induced at said magneto coil 22.

[0058] 65 is the halt switch cable extending from said unit block B and to be connected to said halt switch 44. 66 is the high tension cable connected to the secondary side of the ignition coil 28 in said unit block 3 and the plug cap 67 thereof is connected, to the ignition plug 29 of the internal combustion engine.

[0059] In the time totaling unit constructed in this way, the time totaling meter and the ignition device of the internal combustion engine can be formed in one-body and these can be handled as one unit block. Further, a whole ignition control system of the internal combustion engine can be formed in compact size and its operational reliability can be improved.

[0060] Fig. 8 shows another time totaling unit. In this structure, the time totaling meter 1 having the first count memory means 7A and the second count memory means 7B shown in Fig. 5 is formed in one-body as one unit block 3 together with the ignition device.

[0061] Further in Fig. 8, the re-setting means 50 as the re-set switch shown in Fig. 5 is provided on the time totaling meter 1. This re-setting means 50 is connected to said second count memory means 73 via the circuit molded in said unit block 3.

[0062] By manipulating this re-setting means 50, the second counter can be reset and restarted. By manipulating a selector switch of the display means, total operation time stored in each of the first count memory means 7A and the second count memory means 7B can be displayed selectively on the display means 8.

[0063] Therefore, the time totaling meter and the ignition device can be molded in one-body together with the circuit connection with the halt switch cable to bring ignition operation by this ignition device to a halt so that the ignition system having the function to halt the ignition control can be realized by one unit block and a whole system of said ignition circuit can be formed in smaller size and its operational reliability can be improved.

[0064] Fig. 9 shows a preferred embodiment of the time totaling meter. This time totaling meter 1A comprises the induction coil 72 provided in the case 71 formed from synthetic resin in an approximately square shape, wherein in the induction coil 72 is induced an electromagnetic wave generated from the ignition device.

[0065] Further in this case 71, the waveform shaping circuit (not shown in the drawing) to shape the output waveform of the induction coil 72, the count memory means to count pulses after waveform shaping, and the display means to display the result of counting and the cumulative operation time of the engine are provided.

[0066] Further, 73 is the display window of the display means provided on the case 71, and 74 and 75 are notched parts formed the upper and lower surfaces of the case 71 at one corner thereof near to said induction coil 72 so as to form a notch 76 having a predetermined thickness.

[0067] In said notch 76, multiple holes 77 (only two in Fig. 9) are formed in parallel. An antenna lead 78 is inserted into each hole 77 so as to bend one end thereof. 79 is a splicer such as crocodile clip connected to another end of this antenna lead 78. 80 is the high tension cable (ignition cap cable) connected to the ignition plug 81 via a plug cap 82, and said splicer 79 connects to the core of the tension cable 80 through a hole in the insulation thereof.

[0068] In such time totaling meter, the antenna lead 78 attached with the splicer 79 can be firmly connected to the notch 76 by inserting the end thereof into two holes 77 provided on the notch 76 so as to have the angle of 45a against the side face of the case 71.

[0069] By connecting the splicer 79 to the high tension cable 80, an electromagnetic wave can be obtained by the antenna lead 78 via the high tension cable 80 and then detected by the induction coil 72. Therefore, after treatment of this detected output by each circuit in the case 71, the operation time of the engine can be detected at highly sensitive level and can be displayed on the display window 73.

[0070] Further in this time totaling meter, the end of the antenna lead 78 inserted into said holes 77 is within the level of the notched parts 74 and 75 and housed within the level of the total thickness of the case 71. Thus, wiring of the antenna lead 78 is easier.

[0071] Furthermore, because no convex parts are formed to attach the antenna lead 78, space occupied by the case 71 can be minimized so that not only the size of outer and inner package boxes can be reduced and the cost for the package can be reduced, also the time totaling meter can be attached on a narrower space near the internal combustion engine.

[0072] Further, even if the separately prepared time totaling meter 1 is connected to the unit block 3 via the cables 68 as shown in Fig. 6, it is desirable to form the time totaling meter 1 as shown in Fig. 10.

[0073] That is, the notched part 83 is formed on one corner of the time totaling meter 1 to form a trapezoid notch 81 having a pre-determined thickness.

[0074] Then, said part 3 of the ignition device is provided on said notch 81 and each of the cables 68 is connected to this part 3. Thereby, the end of each cable 68 on said notch 81 can be housed within the level of said notched part 82 of the time totaling meter 1 so that wiring of each cable is easier.

[0075] In addition, because there is no lump formed on the main body of the time totaling meter 1 for attachment of each cable 68, space occupied by this time totaling meter 1 can be minimized, the size and preparation cost of the package can be reduced, and the time totaling meter can be easily attached on a narrower space.

Claims

1. A time totaling meter (1A) comprising:

an antenna to have induced therein an electromagnetic wave from a high tension cable (80) of an ignition circuit,

a waveform shaping means (5) to shape the output waveform from an induction coil (72);

count memory means (7) to count and store output pulses shaped by said waveform shaping means (5);

display means (8) to display the count output by said count memory means (7); and

a case (71) to house said induction coil (72), waveform shaping means (5), count memory means (7) and display means (8);

   characterised in that said time totaling meter further comprises:

an antenna lead (78) for connecting to a high tension cable (80) wherein said induction coil (72) is provided near an end of said antenna lead (78); and

a notch (76) having a predetermined thickness is formed on at least one corner of said case (71) and multiple holes (77) are formed in said notch (76) so as to penetrate said notch (76) and to be inserted through with the end of said antenna lead (78).

Ansprüche

1. Zeitzähler (1a) mit:

einer Antenne, um in dieser eine elektromagnetische Welle von einem Hochspannungskabel (80) eines Zündschaltkreises induziert zu haben,

einem Wellenverlauf formenden Mittel (5), um den Ausgabewellenverlauf von einer Induktionsspule (72) zu bilden,

Zählspeichermittel (7), um Ausgabeimpulse zu zählen und zu speichern, die durch die Wellenverlauf formenden Mittel (5) geformt sind,

Anzeigemittel (8), um die Zählausgabe durch das Zählspeichermittel (7) anzuzeigen, und

einem Gehäuse (71), um die Induktionsspule (72), die Wellenverlauf formenden Mittel (5), die Zählspeichermittel (7) und die Anzeigemittel (8) aufzunehmen,

dadurch gekennzeichnet, dass der Zeitzähler weiterhin aufweist:

einen Antennenleiter (78) zum Verbinden mit einem Hochspannungskabel (80), wobei die Induktionsspule (72) in der Nähe eines Endes des Antennenleiters (78) bereitgestellt ist, und

dass eine Nut (76) mit einer vorgegebenen Dicke auf zumindest einer Ecke des Gehäuses (71) gebildet ist, und dass mehrere Löcher (77) in der Nut (76) gebildet sind, um die Nut (76) zu durchdringen und durch die das Ende des Antennenleiters (78) einzuführen ist.

Revendications

1. Compteur de temps totalisateur (1A) comprenant :

une antenne dans laquelle est induite une onde électromagnétique depuis un câble à haute tension (80) d'un circuit d'allumage,

des moyens de formage d'onde (5) pour conformer la forme d'onde de sortie à partir d'une bobine d'induction (72);

des moyens de comptage à mémoire (7) pour compter et stocker les impulsions produites, conformées par lesdits moyens de formage d'onde (5);

des moyens d'affichage (8) pour afficher la sortie de comptage par lesdits moyens de comptage à mémoire (7); et

un boîtier (71) pour loger ladite bobine d'induction (72), les moyens de formage de forme d'onde (5), les moyens de comptage à mémoire (7) et les moyens d'affichage (8);

   caractérisé en ce que le compteur de temps totalisateur comprend en outre :

un conducteur d'antenne (78) pour connexion à un câble à haute tension (80), dans lequel ladite bobine d'induction (72) est placée à proximité d'une extrémité dudit conducteur d'antenne (78), et

un cran (76), d'une épaisseur prédéterminée, est formé sur au moins un angle dudit boîtier (71), et une pluralité de trous (77) sont formés dans ledit cran (76), de manière à pénétrer dans ledit cran (76) et à être insérée à travers avec l'extrémité dudit conducteur d'antenne (78).

Drawing