JPS5852323Y2 - Catalyst protection circuit - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a circuit for protecting a catalyst provided in the middle of an exhaust pipe for purifying engine exhaust gas.

In automobiles that are equipped with a catalytic converter such as an oxidation catalyst or three-way catalyst in the middle of the exhaust pipe to remove harmful components from engine exhaust gas, the engine is placed on the drive wheel side when combustion does not occur within the engine. When the piston is operated by being driven in the opposite direction, fuel is taken in and discharged, and raw gas flows into the catalytic converter.

Then, if the catalytic converter was at a high temperature due to the heat of the exhaust gas, there was a risk that the raw gas flowing in would cause combustion and burn out the catalyst.

This idea was made in view of the above points, and aims to protect the catalyst by using a warning device such as a buzzer to notify when there is a risk of raw gas flowing into the catalytic converter.

Hereinafter, the content of this invention will be explained with reference to embodiments of the accompanying drawings.

In the figure, Sl is a first switch that is turned off only when the transmission is in the neutral position and turned on when it is in other positions, and is operated by the transmission lever or a member interlocked therewith.

S2 is a second switch that is turned on when the vehicle is running and turned off when the vehicle is stopped, and may be a switch that is activated by the rotation of a wheel or a member linked thereto.

S2 is a switch that is turned off when the ignition switch is on and turned on when it is off, and has a switch that is turned on and off by the ignition key in the opposite direction to the ignition switch, or has a normally closed contact that is turned off when the ignition circuit is energized. A relay coil may be inserted and its normally closed contacts may be used.

1 is a battery power source, 2 is a warning device such as a buzzer or a lamp, and the first to third switches S□.

S2. S3 and warning device 2 are connected in series to battery power source 1.

On the other hand, 3 is an ignition coil, 4 is a detection circuit that detects the energization state of the ignition coil 3, and 5 is a relay controlled by this detection circuit 4, which has a normally closed relay contact S4. It is connected in parallel to the third switch S3 as a fourth switch.

The detection circuit 4 includes a detection coil, a diode D, a capacitor C, a comparison circuit 6 using an operational amplifier, a switching transistor TR, and resistors R□ to R5.

The voltage of power supply 1 is connected to the inverting input terminal of comparator circuit 6 through resistor R2.
A low reference voltage F divided by and R3 is applied.

The transistor TR is connected in series with a collector resistor R5 and a relay coil Ry between the positive side of the power supply 1 and the ground, and is controlled on/off by the blade of the comparator circuit 6 via the base resistor R4.

Therefore, when the ignition coil 3 is not energized, no current is generated in the detection coil L, so the input voltage Vc input to the non-inverting input terminal of the comparator circuit 6 is zero.
Since the output of the comparator circuit 6 is at a low level (O or negative potential), the transistor TR is off, and the relay coil Ry is not energized, so the normally closed relay contact S4 is on.

When the ignition coil 3 is energized, an intermittent alternating current is generated in the detection coil L due to mutual induction.

The current is rectified by diode D, and capacitor C
Charge and smooth.

Thereby, the input voltage V which is the terminal voltage of capacitor C
c becomes higher than the reference voltage vF, and the output of the comparator 6 is inverted and becomes a high level (positive potential).

Therefore, transistor TR is turned on, relay coil Ry is energized, and its relay contact S4 is turned off.

According to this embodiment configured in this way, the first switch S1 is turned on when the transmission is in a position other than the neutral position, and the second switch S2 is also turned on when the vehicle is running. It has become.

Therefore, when the ignition switch is turned off, the third switch S3 is turned on and the warning device 2 is activated to issue a warning.

In other words, at this time, the ignition switch is off, so the engine is not ignited and no fuel is burned, but since the engine is driven in reverse from the driving wheels, fuel is taken in and exhausted, and raw gas is sent to the catalytic converter (not shown). This is because there is a risk that it will flow in.

If you put the transmission in neutral or apply the brakes to stop the vehicle, the warning will stop and the catalyst can be protected.

In addition, the ignition switch is on, so even when the third switch S3 is off, the ignition coil may not be energized due to a malfunction in the ignition circuit, but even in such a case, the ignition will not ignite and the ignition coil will not ignite. Raw gas that is not combusted may flow into the catalytic converter.

In that case, the input voltage Vc is not generated in the detection circuit 4, and the transistor TR is turned off, so the relay coil R
y is not energized, normally closed relay contact (fourth switch)
S4 is turned on.

Therefore, even in such a case, the warning device 2 is energized and a warning is issued.

Furthermore, when the transmission is in the neutral position, the drive wheels and engine crankshaft are disconnected, so the engine is not driven quickly from the drive wheels side, and raw gas is not exhausted, which is a problem. There isn't.

As explained in the embodiments above, according to this invention, when the transmission is in a position other than neutral and the vehicle is running, the ignition coil is no longer energized due to the ignition switch being turned off or due to a malfunction in the ignition circuit. Since a warning is sometimes issued, a warning is always issued when there is a risk of raw gas flowing into the catalytic converter, and it becomes possible to take immediate countermeasures.

Therefore, the raw gas undergoes combustion in the catalytic converter,
It is possible to prevent the catalyst from burning out and protect the catalyst.

[Brief explanation of the drawing]

The figure is a circuit diagram showing an embodiment of this invention. 1...Battery power supply, 2...Warning device, 3...Ignition coil, 4...
-Detection circuit, 5...Relay, S...
First switch, S2...Second switch,
S4... Normally closed relay contact (fourth switch)
, S3...Third switch.

Claims (1)

[Scope of utility model registration request] A first switch that is off only when the transmission is in the neutral position and on when the transmission is in any other position, a second switch that is on when the vehicle is moving and off when the vehicle is stationary, and a second switch that is on when the ignition switch is on. The third switch is off when the ignition switch is off and turns on when the ignition switch is off.
A switch and a warning device such as a buzzer are connected in series to the power source, and a detection circuit is also provided to detect the energization state of the ignition coil.When the ignition coil is energized by the detection circuit, the ignition coil is turned off and the energization is turned off. A catalyst protection circuit comprising: a fourth switch that is controlled to be turned on when the switch is not turned on in parallel with the third switch.