JPS6060355A - Toothed belt device - Google Patents

Abstract

PURPOSE:To reduce the maintenance of a car and to prevent a breakage of an engine due to slipping of a toothed belt by disposing means for optically detecting a gap at an engagement portion on both sides of the engagement portion of a pulley with a toothed belt. CONSTITUTION:Small holes are bored through a U-shaped bracket 11 on both sides of an engagement portion 44 of a cam pulley 2 with a toothed belt 4, and lead wires 15, 16 are inserted in the small holes 13, 14 and retained by adhesive hardening agents 21, 22 and pressing washers 23, 24. A photoelectric chamber 25 and a photoelectric element chamber 27 are connected to the other ends of the lead wires 15, 16. In this arrangement, when one tooth of the toothed belt 4 falls off, a gap is produced at an engagement portion 44 of the pulley 2 with the toothed belt 4 and the gap is detected by photo detecting means, which can easily indicate the time for replacing the toothed belt 4 to prevent an increase in the car maintenance cost and prevent a breakage of an engine due to slipping of the toothed belt 4.

Description

[Detailed description of the invention] (Technical field) The present invention relates to a toothed belt device.

(Prior art) For example, in an automobile internal combustion engine, the camshaft is driven by obtaining rotational force from the crankshaft, so it is necessary to transmit power between the camshaft and the crankshaft, and there are various power transmission devices. A toothed belt device is used to improve quietness.

Such a device is shown in FIG.
(See Publication No. 76343).

This example is applied to a diesel engine, and the crankshaft, camshaft, and tilt pump drive shafts are equipped with pulleys with teeth at a constant pitch on their outer peripheries as crank pulley 1, cam pulley 2, and pump pulley 3, respectively. A toothed belt 4 having teeth of the same pitch on the inner periphery is wound around these pulleys 1°2.3.

Therefore, when the crankshaft rotates, this rotational driving force is transmitted by the toothed belt 4.
In such a belt drive, the toothed belt 4 stretches due to the load, so a predetermined tension is applied to the toothed belt 4 by the belt tensioner.

That is, one of the two idler pulleys 5 and 6 presses the toothed belt 4 from the outside.

In addition, matching marks 7, 8, 9 are provided on the side surfaces of each of the pulleys 1 to 3 and on the side surface of the toothed belt 4, respectively, so that the camshaft and the injection pump are rotated synchronously by the crankshaft.

Therefore, as long as these matching marks 7 to 9 match, the opening/closing timing of the intake and exhaust valves and the fuel injection timing will be optimally controlled.

By the way, since the toothed belt 4 is usually made of rubber, it has a short lifespan compared to the metal chain used in the transmission device or the engine itself. Some of the teeth may become crooked,
This loose tooth causes slippage between the toothed belt 4 and the pulleys 1 to 3.

As a result, the matching marks 7 to 9 will be shifted, and the opening and closing timing of the intake and exhaust valves will be out of order, causing interference between the piston and the intake and exhaust valves, and in severe cases, the engine may be damaged.

Therefore, as a preventive measure, the toothed belt 4 is periodically inspected visually or replaced regularly.

However, visual inspection results in variations depending on the person in determining when it is time to replace the product, and replacing it early increases costs. On the other hand, if the vehicle is used beyond its limits, it may cause engine abnormalities as mentioned above, and even cause secondary disasters while the vehicle is being driven.

In addition, if it were to be replaced periodically, there was a problem in that due to variations in usage conditions, the safety factor had to be increased to replace it earlier, resulting in increased costs.

(Object of the Invention) Therefore, the present invention provides that, before the toothed belt slips,
By focusing on teeth falling off as a sign of this, and by detecting gaps in the meshing part due to teeth falling off, the permissible limits of toothed belts can be easily detected early. An object of the present invention is to provide a toothed belt device that prevents increases in vehicle maintenance costs due to periodic inspections and periodic replacements, and also prevents engine abnormalities due to toothed belt slip.

(Structure and operation of the invention) Therefore, in a toothed belt device that transmits power by winding a toothed belt having teeth of the same pitch around a pulley having teeth of a partial pitch on the outer periphery, the toothed belt Means for optically detecting a gap created in the meshing portion between the pulley and the toothed belt due to the tooth falling out is provided close to both sides of the meshing portion.

The failure process of a toothed belt begins with a crack forming at the bottom of one tooth, which causes the tooth to separate and fall off.

Therefore, when one tooth falls off, a gap is created between the meshing part of the pulley and the toothed belt, and this gap is detected by the optical detection means.For example, a signal from this detection means lights up an alarm lamp inside the vehicle. If you do this, you will easily know that a tooth has fallen off on the toothed belt.

(Example) The following description will be made based on the illustrated embodiments.

FIG. 2 is a partial sectional view of the first embodiment of the present invention, in which gap detection means is provided near the cam pulley 2. In FIG.

In other words, the meshing between the cam pulley 2 and the toothed belt 4)11
A small hole 13.14 is passed through the hole 13.14, one end of a lead wire 15.16 made of glass fiber is inserted from the outside, and an adhesive hardening agent 21.22 and a press-fit washer 23.24 are inserted into the small hole 13.14. It is held by the support bracket 11.

In this state, the axes of the ends of the lead wires 15 and 16 are aligned, and the teeth 40 of the toothed belt 4 (see FIG. 5) cross these axes.

FIG. 3 is a circuit configuration diagram, in which the other end of one of the lead wires 15 is introduced into the light source chamber 25, and the other end of the other lead wire 16 is introduced into the photoelectric element chamber 27.

In the medium of a glass fiber with a high refractive index, light travels in the fiber axis direction while being totally reflected, so when the light from the lamp 26 enters from one end surface 17 of the lead wire 15, this light will be transmitted even if the lead wire 15 is bent. The signal is transmitted to the other end surface 18.

If there is nothing blocking the light that has reached the other end surface 18 and one end surface 19 of the other lead wire 16 whose axes coincide with each other, the light travels straight and enters this end surface 19 .

This light is transmitted to the other end surface 20, and is converted into an electrical signal by a photoelectric element 28 provided opposite to the other end surface 2o.

That is, the optical transmission path formed between one lead wire end surface 18 and the other lead wire end surface 19 is blocked by the close meshing of the toothed belt 4 and the pulley 2 (the teeth of the toothed belt 4 40 and the teeth 42 of the pulley 2 alternately pass across each other without a gap), but if the teeth of the toothed belt 4 fall off, this will cause the gap 44 (in Figs. 2 and 3, the gap 44 to pass through the optical transmission path. light is transmitted through the

The amplifier 30 in the amplifier room 29 is connected at one end to the photoelectric element 28 and at the other end to the coil 32 of the relay 31, and transmits the weak signal converted into an electric signal by the photoelectric element 28 to the contact 3.
3 to an electrical signal that can be closed.

One side of the contact 33 of the relay 31 is connected to the power source 35 via the ignition switch 36, and the other side is connected to the alarm lamp 3.
Connected to 4. The alarm lamp 34 is attached to the instrument panel inside the vehicle like other alarm lamps.

Therefore, when current flows through the coil 32, the contact 33 closes and the alarm lamp 34 lights up.
2 and contact 33 are connected, and the relay 31 has a self-holding function. Note that the illuminated alarm lamp 34 is released from self-holding by opening the ignition switch 36.
Lights out.

The effect of the above configuration will be explained.

The process of damage to the toothed belt 4 is as follows: (1) a crack occurs in the tooth bottom 42 of one tooth 41, (2) this tooth 41 peels off (see FIG. 4), and (2) falls off. If this phenomenon occurs in other teeth as well,
It can be divided into various stages: many teeth fall out, and finally belt slip occurs.

Among these, if the tooth 41 falls out in the third stage, until then,
A gap 44 (FIG. 5) corresponding to the tooth 41 that fell off is created in the meshing portion that had been meshing without a gap.

When this gap 44 rotates and crosses the optical transmission path between the lead wire end faces 18 and 19 (as shown in FIGS. 2 and 3), light is transmitted through this gap 44, and the photoelectric element 28 detects this light. The signal is converted into an electric signal, and this electric signal causes current to flow through the coil 32 of the relay 31.

Therefore, the contact 33 of the relay 31 is closed, current flows from the power source 35 to the alarm lamp 34, and the alarm lamp 34 lights up, notifying the driver in the vehicle that the teeth of the toothed belt 4 have fallen off, and relaying 31 is self-held, the contact 33 is kept closed until the ignition switch 36 is opened, and the alarm lamp 34 continues to be lit.

On the other hand, even in the second stage of the damage process described above, the peeled tooth 41 may curl up and bite into the tooth tip 45 of the pulley 2, creating a gap 46 around the rolled tooth 41 (see Figure 6). ).

In this case as well, light is transmitted through the gap 46 and the alarm lamp 34 lights up.

Therefore, if a gap 44 is created in the meshing part due to the teeth of the toothed belt 4 falling off, the alarm lamp 34 lights up, so there is no need to open the engine room or perform regular inspections, and the teeth can be easily attached inside the vehicle. Know it's time to replace the belt.

Further, in this example, the lamp 26 as a light emitting part and the photoelectric element 28 as a light receiving part, together with the amplifier 30, are provided separately from the engine main body 10.

When detecting the gap 44 that occurs at the meshing part between the toothed belt 4 and the pulley 2, basically, a lamp 26 and a photoelectric element 28 are arranged facing each other on both sides of the meshing part as in the second embodiment shown in FIG. However, these 26.28 are the engine body 1.
If it is directly assembled near zero, it will be affected by the high temperature (100°C to 140°C) and severe vibration from the engine body 10, and the life of the toothed belt 4 is usually long (100,000 to 2
00,000 km), the lifespan of the lamp 26 and the photoelectric element 28 may be shorter.

However, glass fiber (covered with vinyl, etc.) is resistant to heat and vibration, and is easy to install.
On the other hand, the lamp 26 and the photoelectric element 28 can be installed in a place with a good usage environment.
The effect of improving the personnel requirements for the detection means can be obtained.

For this reason, in some cases the lamp 26 or the photoelectric element 28
Of course, it is also possible to assemble either one of them near the engine main body 10.

Furthermore, the mounting location of the detection means is not limited to the cam pulley 2, but may be any other pulley as long as it meshes with the teeth of the toothed belt 4, and the gap detection can be similarly applied even if ultrasonic waves are used in addition to light. be done.

Furthermore, when used in combination with a toothed belt with decoy teeth, in which at least one tooth of the toothed belt is provided as a decoy tooth that is more easily damaged than other teeth, the accuracy of detecting when it is time to replace the belt will be further improved. do.

(Effects of the Invention) As described above, according to the present invention, means for optically detecting the gap created in the meshing part of the toothed belt and the pulley due to the falling off of the tooth of the toothed belt is provided on both sides of the meshing part. Since they are installed in close proximity, if a warning lamp inside the vehicle is lit in conjunction with this detection means, it will be easy to know when the toothed belt should be replaced even from inside the vehicle, and periodic inspections of the toothed belt can be carried out. It is possible to reduce costs by preventing increases in vehicle maintenance costs due to periodic replacement, and it also has the effect of preventing damage to the engine due to the toothed belt being used until it slips. It will be done.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional toothed belt device. FIG. 2 is a partial sectional view of the first embodiment of the present invention, FIG. 3 is a circuit configuration diagram, FIGS. 4, 5, and 6 are action explanatory diagrams, and FIG. FIG. 2 is a circuit configuration diagram of a second embodiment. 1.2,3...Pulley, 4...Toothed belt, ll.
... Bracket, 15.16 ... Lead wire, 17.1
8゜19.20...Lead wire end face, 26...Lamp, 28...Photoelectric element, 30...Amplifier, 31...
Relay, 34...Alarm lamp, 40...Toothed belt teeth, 41...Peeled teeth, 44.46...Gap. Figure 3 Figure 4 Figure 1 Figure 5 Figure 6

Claims (1)

[Claims] In a toothed belt device that transmits power by wrapping a toothed belt with teeth of the same pitch around a pulley with teeth of a constant pitch on the outer periphery, the pulley and the toothed belt may fall off due to the teeth of the toothed belt falling off. A toothed belt device characterized in that means for optically detecting a gap generated in the meshing portion is provided close to both sides of the meshing portion.