JPS63988Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a control device for an intake throttle valve in a diesel engine, and more specifically, to burn out particles trapped in an exhaust particle collector installed in an exhaust system. The present invention relates to a control device for an intake throttle valve that throttles the intake air.

It has long been known that the exhaust system of a diesel engine can be equipped with a particle collector that captures combustible particles such as carbon particles in the exhaust gas and prevents them from being released into the atmosphere. There is.

The particle collector has a heat-resistant filter structure, and as the amount of trapped particles increases, the filter structure becomes clogged and interferes with normal exhaust gas flow. Therefore, in order for the particle collector to be used without interfering with the normal flow of exhaust gas, the particles trapped in the particle collector must be periodically removed from the particle collector. Regeneration needs to occur.

Particle collector regeneration can be accomplished in a variety of ways, one of which is to reduce the flow rate of air into the diesel engine.
That is, the intake air is throttled to raise the exhaust gas temperature above the combustion temperature of the particles captured by the particle collector,
A method has already been proposed in which the particles are burned away in a particle collector by the heat of the exhaust gas.

Intake throttling for regeneration of the particle collector allows the exhaust gas temperature to rise to the temperature required for regeneration of the particle collector, without significantly impairing the drivability of the diesel engine. This must be done in accordance with the engine operating condition so as not to emit a large amount of black smoke, and the opening degree of the intake throttle valve must be variably set depending on the engine operating condition.

An object of the present invention is to provide a control device that can control an intake throttle valve to an appropriate opening depending on the operating state of the engine in response to the above-mentioned requirements.

According to the present invention, the purpose is to provide a control device for an intake throttle valve that throttles the intake air in order to burn out particles captured in an exhaust particle collector installed in the exhaust system of a diesel engine. A diaphragm device that drives the intake throttle valve to close in response to an increase in fluid pressure introduced; and an electromagnetic control valve that connects the diaphragm chamber to a fluid pressure source when energized and opens the diaphragm chamber to the atmosphere when not energized. a load measuring means for measuring the load of the diesel engine; a rotational speed measuring means for measuring the rotational speed of the diesel engine; and an increase in the engine load measured by the load measuring means and an increase in the engine load measured by the rotational speed measuring means. and control means for reducing the duty ratio of the pulse signal applied to the electromagnetic control valve in response to each increase in engine rotational speed. .

According to the above-described configuration, the opening degree of the intake throttle valve during regeneration of the particle collector is variably set according to the engine load and engine speed, and thereby particle capture can be performed without impairing engine operability. Intake throttling is performed to regenerate the collector.

The opening degree of this intake throttle valve is controlled according to the fluid pressure introduced into the diaphragm chamber of the diaphragm device, and the fluid pressure introduced into the diaphragm chamber is controlled by an electromagnetic control valve, which controls the duty ratio of the pulse signal. The fluid pressure supplied to the diaphragm chamber is controlled by alternately communicating the fluid pressure source with the atmosphere at a time ratio corresponding to The opening of the intake throttle valve also varies in a small range around the control target opening based on the duty ratio, and as a result, the particle collector A better intake throttling condition for regeneration and a better intake throttling condition for engine drivability occur alternately and repeatedly, and each intake throttling condition does not occur continuously for a long time, so the effects of both conditions are This makes it possible to regenerate the particle collector reliably in a short period of time without impairing engine operability.

Furthermore, as mentioned above, in the control device according to the present invention, the higher the load and the higher the speed of operation of the diesel engine, the smaller the duty ratio becomes. As a result, during high-load, high-speed operation, the excess air ratio of the diesel engine decreases and the amount of oxygen in the exhaust gas decreases, but the exhaust gas flow rate remains slightly higher and lower. As a result, a state in which the oxygen required for regeneration of the particle collector is obtained and a state in which the exhaust gas temperature necessary for regeneration of the collector is obtained are alternately and repeatedly generated. Therefore, the particle collector can be regenerated well even during high-load and high-speed operation.

Due to failures such as disconnection of the control means or solenoid control valve,
Alternatively, when fluid pressure is no longer supplied to the diaphragm chamber due to a failure in the fluid pressure source, the intake throttle valve will be in the fully open position, even if the particle collector is no longer regenerated. Melting of the particle collector and deterioration of engine drivability due to excessive intake throttling are avoided, and a so-called fail-safe is achieved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram showing one embodiment of a diesel engine incorporating a control device according to the present invention. In the figure, reference numeral 1 indicates a diesel engine, and the diesel engine 1 sucks air into a combustion chamber (not shown) from an intake manifold 2, and injects fuel into the combustion chamber from a fuel injection nozzle (not shown). The exhaust gas is injected into the exhaust manifold 3, the exhaust pipe 4, and the particle collector 5.
The gas is then discharged into the atmosphere through an exhaust pipe 6. The amount of fuel injected into the combustion chamber from the fuel injection nozzle is controlled by a fuel injection pump 7, thereby controlling the load on the diesel engine 1.

The particle collector 5 has a heat-resistant filter structure and is designed to trap combustible particles such as carbon particles in the exhaust gas while allowing the exhaust gas to freely flow.

The intake manifold 2 is provided with an intake throttle valve 8 that controls the flow rate of air taken into the combustion chamber. The intake throttle valve 8 is configured as a butterfly valve supported on a valve shaft 8a, and is connected to a rod 11 of a diaphragm device 10 via a lever 9.
It is adapted to be driven by the diaphragm device. The diaphragm device 10 has a diaphragm 12, and as the negative pressure introduced into the diaphragm chamber 13 increases, the diaphragm 12 moves to the right in the figure against the spring force of the compression coil spring 14, thereby increasing the intake air. The throttle valve 8 is driven in the valve closing direction, that is, in the direction in which intake throttle is performed.

The negative pressure generated by the negative pressure pump 15 is transferred to the diaphragm chamber 13 through a conduit 16, a negative pressure control valve 17, and a conduit 1.
8 and is selectively supplied.
The negative pressure control valve 17 is configured as an electromagnetically operated three-way switching valve, and when the electromagnetic device is energized, the port a connected to the conduit 18 is connected to the port b connected to the conduit 16, On the other hand, when the electromagnetic device is not energized, port a is connected to air intake port c instead of port b. A constant frequency pulse signal is given from the control device 19 to the electromagnetic device of the negative pressure control valve 17, so that port a is connected to port b and port c.
The pulse signal is repeatedly connected to the pulse signal at a predetermined time ratio according to the duty ratio of the pulse signal. As a result, a large negative pressure is generated at port a in response to an increase in the duty ratio of the pulse signal applied to the electromagnetic device of the negative pressure control valve 17, and in response to an increase in this negative pressure, the intake throttle valve 8 The degree of aperture increases. An example of the opening characteristic of the intake throttle valve 8 with respect to the duty ratio of the pulse signal is shown in FIG. In the graph shown in Figure 2, the intake throttle valve 8 is fully opened when the duty ratio is 0.2 or less, and when the duty ratio is between 0.2 and 0.8, it is closed in proportion to the increase in the duty ratio. , it is designed to be fully closed when the duty ratio is 0.8.

When the air intake is throttled by the intake throttle valve 8 and the flow rate of air taken into the combustion chamber is reduced, the excess air in the combustion chamber is reduced, causing the exhaust gas temperature to rise, which reduces particle capture. The particles trapped in the collector 5 are burned out, and the particle collector is regenerated. The intake air throttle during particle collector regeneration must be done so as not to significantly impede the drivability of the diesel engine at this time, and to prevent the diesel engine from emitting large amounts of black smoke due to lack of intake air. Therefore, the appropriate opening degree of the intake throttle valve 8 varies depending on the engine load and engine speed, and increases as the engine load and engine speed increase.

The control device 19, as shown in FIG.
The optimum duty ratio corresponding to the appropriate intake throttle valve opening according to the engine load and engine speed is stored in the storage device, and when the particle collector 5 is regenerated, the engine load ratio provided in the fuel injection pump 7 is stored. The optimum duty ratio corresponding to the engine load and engine rotation speed measured by the sensor 20 and the engine rotation speed sensor 21 is read from the storage device, and a pulse signal of a duty ratio corresponding to the optimum duty ratio is sent to the negative pressure control valve 17. It is designed to output to an electromagnetic device.

Further, the control device 19 is adapted to determine the regeneration timing of the particle collector 5 according to the pressure measured by the pressure sensor 22. The pressure sensor 22 is connected to the exhaust pipe 4 via a conduit 23 and is connected to the particle collector 5.
The exhaust gas pressure generated in the exhaust passage on the more upstream side is measured. The control device 19 is
As shown in FIG. 4, when the amount of particles captured by the particle collector 5 is substantially 0, the exhaust gas generated in the exhaust passage upstream from the particle collector 5 under each engine speed. The exhaust gas pressure generated in the exhaust passage upstream of the particle collector 5 at each engine speed when the gas pressure, that is, the initial exhaust gas pressure B and the amount of particles captured by the particle collector 5 reach a predetermined value. (Comparison predetermined value) A is stored in each storage device, and the memory value corresponding to the engine rotation speed measured by the rotation speed sensor 21 is compared with the exhaust gas pressure measured by the pressure sensor 22, and the pressure sensor When the exhaust gas pressure measured by 22 is equal to or higher than a predetermined comparison value determined according to the engine speed, it is determined that it is time to regenerate the particle collector.

Next, the operation of the control device of the present invention will be explained with reference to the flowchart shown in FIG.
Note that the routine shown in this flowchart is repeatedly executed at predetermined times or every predetermined crank angle.

First, in step 1, the engine load sensor 2
0, the engine speed N measured by the engine speed sensor 21, and the exhaust gas pressure EP measured by the pressure sensor 22 are read. In step 2, a comparison predetermined value A is determined according to the engine speed N as shown in FIG. In the next step 3, it is determined whether the exhaust gas pressure EP measured by the pressure sensor 22 is greater than a predetermined comparison value A. When EP≧A, that is, when the exhaust gas pressure EP is less than the predetermined comparison value A, the process proceeds to step 4, and in step 4, it is determined whether the particle collector regeneration execution flag F is 1 or not. It will be done. When the flag F is 1, it means that the particle collector is being regenerated. Therefore, if the regeneration of the particle collector is not being executed at this time, the process proceeds to step 5, where the flag F is set to 0, and in step 6, an off signal is output to the electromagnetic device of the negative pressure control valve 17. . As a result, port a of negative pressure control valve 17 is continuously connected to port c, and as a result, atmospheric pressure is introduced into diaphragm chamber 13, and intake throttle valve 8 is maintained at the fully open position.
In other words, intake throttling is not performed.

In step 3, when EP≧A, that is, when the exhaust gas pressure EP is equal to or higher than the comparison predetermined value A, it is determined that it is time to regenerate the particle collector 5, and the process proceeds to step 7. The particle collector regeneration execution flag F is set to 1, and then in step 8, the duty ratio D is determined according to the engine load R and the engine speed N as shown in FIG. That is, the duty ratio D is determined to decrease in response to an increase in the engine load R and an increase in the engine speed N, respectively. Then step 9
In this case, a pulse signal having a duty ratio corresponding to the duty ratio D is outputted to the negative pressure control valve 17. As a result, a negative pressure corresponding to the duty ratio is introduced into the diaphragm chamber 13, and the intake throttle valve 8 moves from its fully open position to the valve closing direction and starts intake throttle. The intake throttle valve 8 changes its opening degree according to the engine load and engine speed by controlling the duty ratio as described above, and the opening degree becomes larger when the engine load is low and when the engine speed is low. Conversely, the diesel engine 1 throttles the intake air with a smaller throttle degree as the engine load becomes larger or as the engine speed increases.
By restricting the intake air in this way, the temperature of the exhaust gas discharged from the diesel engine 1 increases without significantly impairing the drivability of the diesel engine 1 and without causing the diesel engine 1 to emit a large amount of black smoke. However, the particles captured in the particle collector 5 are burned away by the heat of the exhaust gas, and the particle collector 5 is regenerated.

Under the execution of regeneration as described above, the negative pressure control valve 1
Since the negative pressure that 7 gives to the diaphragm chamber 13 fluctuates in a wave-like manner depending on the frequency of the pulse signal given to the negative pressure control valve 17, the intake throttle valve 8 changes accordingly.
The opening degree also fluctuates in a small range around the control target opening degree depending on the duty ratio. Good intake throttling conditions occur repeatedly, and each intake throttling condition does not continue for a long time, so the effects of both conditions coexist, and the engine drivability is maintained for a short period of time without impeding engine drivability. The particle collector 5 is reliably regenerated.

When the particle collector 5 is regenerated in this way, the exhaust gas pressure EP decreases, and therefore, when the particle collector 5 is regenerated and a predetermined time elapses, the exhaust gas pressure EP decreases. The value becomes smaller than the predetermined value A, and therefore, in the next routine, the process proceeds to step 4 after step 3. At this time, flag F is set to 1, so next step 10
In this step, the exhaust gas pressure EP
A determination is made as to whether or not the initial pressure B is greater than the initial pressure B. In this step, when EP≧B, the process proceeds to step 8; on the other hand, when EP≧B is not the case, the process proceeds to step 5, and as a result, the exhaust gas pressure EP
Regeneration of the particle collector continues until B falls to the initial pressure B.

When negative pressure is no longer supplied to the diaphragm chamber 13 due to a failure in the control device 19 or the negative pressure control valve 17 or a failure in the negative pressure supply system, the intake throttle valve 8 is located at the fully open position, and the particle collector 5 Even if regeneration is no longer performed, erosion of the particle collector 5 and deterioration of engine operability due to excessive intake throttling are avoided.
A so-called failsafe is performed.

Although the present invention has been described in detail with respect to specific embodiments above, it will be appreciated by those skilled in the art that the present invention is not limited thereto and that various embodiments are possible within the scope of the present invention. It should be obvious.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing one embodiment of a diesel engine incorporating an intake throttle valve control device according to the present invention, Fig. 2 is a graph showing intake throttle valve opening characteristics with respect to duty ratio, and Fig. 3 4 is a graph showing the optimum duty ratio according to the engine load and engine speed, FIG. 4 is a graph showing the comparative predetermined value and initial pressure according to the engine speed, and FIG. 5 is a flowchart. 1... Diesel engine, 2... Intake manifold, 3... Exhaust manifold, 4... Exhaust pipe, 5... Particle collector, 6... Exhaust pipe, 7... Fuel injection pump, 8... Intake throttle Valve, 8a... Valve shaft, 9... Lever, 10... Diaphragm device,
11...Rod, 12...Diaphragm, 13...
...Diaphragm chamber, 14...Compression coil spring, 1
5... Negative pressure pump, 16... Conduit, 17... Negative pressure control valve, 18... Conduit, 19... Control device, 20
...Engine load sensor, 21 ... Engine rotation speed sensor, 22 ... Pressure sensor, 23 ... Conduit.

Claims (1)

[Scope of utility model registration request] A control device for an intake throttle valve that throttles the intake air in order to burn out particles trapped in an exhaust particle collector installed in the exhaust system of a diesel engine. A diaphragm device that drives the intake throttle valve to close, an electromagnetic control valve that connects the diaphragm chamber to a fluid pressure source when energized and opens the diaphragm chamber to the atmosphere when not energized, and a load that measures the load of the diesel engine. a measuring means; a rotational speed measuring means for measuring the rotational speed of the diesel engine;
control means for reducing the duty ratio of the pulse signal applied to the electromagnetic control valve in response to an increase in the engine load measured by the load measurement means and an increase in the engine rotation speed measured by the rotation speed measurement means; An intake throttle valve control device comprising: