JPH0315026B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of operating a diesel engine used in a vehicle such as an automobile, and particularly relates to a method of operating a diesel engine used in a vehicle such as an automobile, and particularly a method of operating a diesel engine that has a particle collector in the exhaust passage and an exhaust gas recirculation device. The present invention relates to an operating method for regenerating a particle collector of a diesel engine that recirculates exhaust gas.

[Prior Art] Exhaust gas recirculation has long been known to suppress the amount of NOx contained in the exhaust gas of internal combustion engines. It is known to install a particle collector with a filter structure in the middle of the exhaust passage in order to prevent particles such as carbon particles from being released into the atmosphere. In addition to incorporating the above-mentioned particle collector to prevent the release of A solution to the problems that arise during the control of circulation has been proposed in Japanese Patent Application No. 151130/1982 and Application No. 157868/1983 filed by the same applicant as the present applicant.

When the amount of particles trapped in the particle collector installed in the exhaust passage of a diesel engine increases,
JP-A-56-124619 discloses that by throttling the intake air of a diesel engine, the temperature of the exhaust gas is temporarily raised, and the particles accumulated in the particle collector are burnt out. It is proposed that

[Problem to be solved by the invention] As proposed in the above-mentioned Japanese Patent Application Laid-open Publication No.
Combustible particles, such as carbon particles, trapped and accumulated in particle collectors built into the exhaust passage of a diesel engine are burned out by increasing the temperature of the exhaust gas by throttling the intake air of the diesel engine. However, if the diesel engine is equipped with a particle collector and an exhaust gas recirculation system as proposed in the above-mentioned patent application, the intake passage will be throttled due to the above-mentioned particle burn-out. As the difference between the gas pressure in the exhaust passage and the intake pressure in the intake passage increases accordingly, the amount of exhaust gas recirculation increases significantly, making the operation of the diesel engine unstable. There is a risk of a decrease in output.

The present invention addresses the above-mentioned problems and, in a diesel engine equipped with a particle collector and an exhaust gas recirculation device, when the particle collector needs to be regenerated, the engine operation as described above is improved. The object of the present invention is to provide a method for operating a diesel engine that can regenerate a particle collector without causing instability or a decrease in output.

[Means for Solving the Problems] According to the present invention, the above-mentioned problems are solved by a particle trap for a diesel engine that has a particle collector in the exhaust passage and is equipped with an exhaust gas recirculation device to recirculate the exhaust gas. using an operating method that regenerates the collector, narrowing the intake passage in order to burn the particles captured by the particle collector;
Meanwhile, the opening degree of the exhaust gas recirculation control valve that controls the exhaust gas recirculation passage that recirculates the exhaust gas from the exhaust passage to the intake passage is decreased as the differential pressure of the exhaust gas at both ends thereof increases. This is achieved by an operating method that is characterized by controlling the vehicle so that it is small.

[Operations and Effects of the Invention] In a diesel engine which has a particle collector in the exhaust passage and is equipped with an exhaust gas recirculation device to recirculate exhaust gas as described above, particles captured by the particle collector When operation is performed to throttle the intake passage in order to combust the exhaust gas, the opening degree of the exhaust gas recirculation control valve that controls the exhaust gas recirculation passage that recirculates the exhaust gas from the exhaust passage to the intake passage is adjusted at both ends. If the exhaust gas pressure is controlled so that it decreases as the differential pressure increases, the exhaust gas will continue to decrease even while the diesel engine is operating with the intake air throttled to regenerate the particle collector. The recirculation amount is maintained at a predetermined normal value while the engine continues to operate in a stable manner producing a predetermined output.

[Example] The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 of the accompanying drawings is a schematic diagram showing a diesel engine equipped with a particle collector and an exhaust gas recirculation device for carrying out the particle collector regeneration operation method according to the present invention. In the figure, reference numeral 1 designates a diesel engine which slidably receives a piston 3 in a cylinder bore 2, the piston defining a combustion chamber 4 above it. The diesel engine 1 has a swirl chamber 5 communicating with a combustion chamber 4,
Liquid fuel for diesel engines is injected into the swirl chamber from a fuel injection nozzle 40.

The diesel engine 1 takes air into a combustion chamber 4 through an intake manifold 6 and an intake port 7, and discharges exhaust gas from the combustion chamber 4 through an exhaust port 8 to an exhaust manifold 9. The intake port 7 and the exhaust port 8 are each opened and closed by poppet valves, and only the exhaust poppet valve 10 is shown in the figure.

An exhaust pipe 11, a particle collector 12, and an exhaust pipe 13 are connected to the exhaust manifold 9 in this order.

An intake pipe 41 is connected to the intake manifold 6, and the intake pipe 41 is provided with an intake throttle valve 42 for controlling the flow rate of air taken into the combustion chamber 4. The intake throttle valve 42 is configured as a butterfly valve carried on a valve shaft 42a, and is connected via a lever 43 to a rod 45 of a diaphragm device 44, so as to be driven by the diaphragm device. The diaphragm device 44 has a diaphragm 46, and as the negative pressure introduced into the diaphragm chamber 47 increases, the diaphragm 46 moves downward in the figure against the spring force of the compression coil spring 48, thereby opening the intake throttle. The valve 42 is driven in the direction of closing the valve, that is, in the direction of throttling the intake air.

Negative pressure generated by a negative pressure pump (not shown) is selectively supplied to the diaphragm chamber 47 via conduits 28, 49, an on-off valve 50, and conduits 51, 52. The on-off valve 50 is configured as an electromagnetically actuated on-off valve, and is closed when the electromagnetic device is not energized, and opened when the electromagnetic device is energized. . In addition, the diaphragm chamber 47 has an on-off valve 53.
More atmospheric pressure is selectively supplied via conduits 54 and 52. The on-off valve 53 is configured as an electromagnetically actuated on-off valve, and is closed when the electromagnetic device is not energized, and opened when the electromagnetic device is energized. . When the on-off valve 50 is energized and the on-off valve 53 is not energized, negative pressure is introduced into the diaphragm chamber 47, thereby increasing the intake throttle degree of the intake throttle valve 42. When the on-off valves 50 and 53 are not energized and the on-off valves 53 are energized, the negative pressure in the diaphragm chamber 47 decreases, causing the intake throttle valve 42 to reduce its degree of restriction. When electricity is not being supplied, fluid pressure is sealed in the diaphragm chamber 47, and the intake throttle valve 42 is held at the opening position at that time.

The control device 3 energizes the on-off valves 50 and 53.
5. The control device 53 may be a well-known microcomputer including a CPU, ROM, RAM, etc., and controls the ROM to set an appropriate intake throttle valve opening (control target opening) according to the engine load and engine speed. I remember,
When the particle collector 12 is regenerated, the fuel injection pump 38
The control target opening corresponding to the engine load and engine speed measured by the pump lever opening sensor 36 and engine speed sensor 37 provided in the ROM is read out from the ROM, and the control target opening and intake throttle valve opening are The actual opening degree of the intake throttle valve 42 measured by the degree sensor 56 is compared with the actual opening degree of the intake throttle valve 42, and the energization of the on-off valves 50 and 53 is controlled based on the comparison result. That is, the control device energizes only the on-off valve 50 when the opening degree of the intake throttle valve measured by the opening degree sensor 56 is larger than the control target opening degree; When the opening is small, only the on-off valve 53 is energized, and when the opening is equal to the control target opening with a certain control tolerance, neither of the on-off valves 50 and 53 is energized. .

As a result, when the particle collector 12 is regenerated, the intake throttle valve 42 is brought to an appropriate intake throttle position according to the operating state of the engine at that time, which increases the exhaust gas temperature and traps it in the particle collector 12. The particles that have been removed are burned away. Note that when the intake pipe negative pressure detected by the negative pressure sensor 57 increases beyond a predetermined value, or when the exhaust gas temperature detected by the exhaust gas temperature sensor 58 increases beyond a predetermined value, the target as described above is reached. The intake throttle degree of the intake throttle valve 42 is reduced in excess of the opening degree control.

14 indicates an exhaust gas recirculation control valve. The exhaust gas recirculation control valve 14 has its inlet port 15 connected by a conduit 16 to an exhaust gas intake port 17 formed in the exhaust manifold 9, and its outlet port 18 connected by a conduit 19 to an exhaust gas intake port 17 formed in the exhaust manifold 6.
The exhaust gas injection port 20 is connected to the exhaust gas injection port 20 formed in the exhaust gas injection port 20 . Exhaust gas recirculation control valve 14 includes valve element 21
The valve element 21 cooperates with the valve seat 22 to open and close the outlet port 18 and to control its effective opening area. This valve element 21 is connected by a valve rod 23 to a diaphragm device 24 and is adapted to be driven by this diaphragm device. The diaphragm device 24 includes a diaphragm 25 which is driven upwards in the figure against the action of a helical compression spring 27 in response to an increase in the negative pressure introduced into its diaphragm chamber 26, and which is driven upwards in the figure against the action of a helical compression spring 27. 21 is moved upwardly to open the outlet port 18 and increase its effective opening cross-sectional area.

Negative pressure generated by a negative pressure pump (not shown) is supplied to the diaphragm chamber 26 through conduits 28, 29, an on-off valve 30, and conduits 31, 32, and atmospheric pressure is supplied through an on-off valve 33 and conduits 34, 32. supply is becoming available.

The on-off valve 30 is configured as a normally closed solenoid valve, and the on-off valve 33 is configured as a normally open solenoid valve. Open/close valve 3
0 and 33 are given pulse signals generated by the control device 35, whereby the on-off valves 30 and 33 are opened and closed at a predetermined time ratio according to the duty ratio of the pulse signals, respectively, and the duty ratio is applied to the conduit 32. It is designed to provide negative pressure according to the ratio. In this case, the larger the duty ratio of the pulse signal, the more the conduit 3
2, a large negative pressure is generated.

The control device 35 stores duty ratio control data corresponding to the engine load and engine speed in ROM in advance, and uses the engine load and engine speed sensor 37 measured by the pump lever opening sensor 36 of the fuel injection pump 38. Search for the duty ratio control data corresponding to the engine speed measured by
This duty ratio control data is read from the ROM and compared with the valve opening amount data measured by the valve opening amount sensor 39 provided in the exhaust gas recirculation control valve 14, and based on the comparison result, a predetermined duty ratio is set. A pulse signal of the ratio is output to the on-off valves 30 and 33. That is, when the duty ratio control data is equal to the valve opening amount data, the control device 35 outputs a pulse signal with the same duty ratio as before, and when the duty ratio control data is greater than the valve opening amount data, the control device 35 outputs a pulse signal with the same duty ratio as before. On the other hand, when the duty ratio control data is smaller than the valve opening amount data, the duty ratio of the output pulse signal is made smaller than before.

The duty ratio control data stored in the ROM is the exhaust gas when exhaust gas recirculation is being performed at a predetermined flow rate determined according to the engine speed and engine load when the intake throttle is not being performed. This is based on the opening amount of the recirculation control valve, and this is stored in the ROM so that it can be read out based on the engine load and engine speed as a target opening amount corresponding to the engine load and engine speed. There is. This target valve opening amount is determined by experiment or theoretical calculation.
Further, the control device 35 measures the differential pressure between the intake system pressure and the exhaust system pressure measured by the differential pressure sensor 60, and based on the correction coefficient as shown in FIG. Correction control is performed to reduce the target valve opening amount.

Therefore, when the particle collector 12 is regenerated, the intake throttle valve 42 throttles the intake air, thereby increasing the negative pressure in the intake pipe and increasing the differential pressure between the intake system pressure and the exhaust system pressure. However, by correcting and controlling the target valve opening amount as described above, the opening amount of the exhaust gas recirculation control valve 14 is reduced as the intake pipe negative pressure increases, so that an appropriate flow rate is maintained at this time as well. Exhaust gas recirculation takes place.

Correction control accompanying an increase in the intake pipe negative pressure during intake throttling may be performed based on a correction coefficient as shown in FIG. 3 in accordance with the intake pipe negative pressure detected by the negative pressure sensor 57. In addition, an appropriate target valve opening amount at the time of intake throttling is stored in advance in the ROM of the control device 35 according to the engine load and engine speed, and the exhaust gas recirculation control valve is controlled based on this stored data at the time of intake throttling. The valve opening amount may be controlled.

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

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a diesel engine equipped with a particle collector and an exhaust gas recirculation control device that implements the particle collector regeneration operation method according to the present invention, FIG. FIG. 3 is a graph showing the valve opening amount correction coefficient of the exhaust gas recirculation control valve. 1... Diesel engine, 2... Cylinder bore,
3...Piston, 4...Combustion chamber, 5...Swirl chamber,
6...Intake manifold, 7...Intake port, 8
...Exhaust port, 9...Exhaust manifold, 10
... poppet valve, 11 ... exhaust pipe, 12 ... particle collector, 13 ... exhaust pipe, 14 ... exhaust gas recirculation control valve, 15 ... inlet port, 16 ... conduit,
17... Exhaust gas intake port, 18... Outlet port, 19... Conduit, 20... Exhaust gas injection port, 21... Valve element, 22... Valve seat, 23...
Valve rod, 24...Diaphragm device, 25...
Diaphragm, 26...Diaphragm chamber, 27...
...Compression coil spring, 28, 29... Conduit, 30...
...Opening/closing valve, 31, 32... Conduit, 33... Opening/closing valve, 34... Conduit, 35... Control device, 36...
Pump lever opening sensor, 37... Engine speed sensor, 38... Fuel injection pump, 40... Fuel injection nozzle, 41... Intake pipe, 42... Intake throttle valve, 43... Lever, 44... Diaphragm Device, 45... Rod, 46... Diaphragm, 4
7...Diaphragm chamber, 48...Compression coil spring, 49...Conduit, 50...Opening/closing valve, 51, 52
... Conduit, 53 ... On-off valve, 54 ... Conduit, 56
...Opening sensor, 57...Negative pressure sensor, 58...
Exhaust gas temperature sensor, 60...Differential pressure sensor.

Claims (1)

[Claims] 1. An operating method for regenerating a particle collector of a diesel engine that has a particle collector in the exhaust passage and is equipped with an exhaust gas recirculation device to recirculate exhaust gas, and the particle collector is The opening of an exhaust gas recirculation control valve that controls an exhaust gas recirculation passage that throttles the intake passage to burn particulates, while recirculating the exhaust gas from the exhaust passage to the intake passage; An operating method characterized by controlling the differential pressure to decrease as the differential pressure increases.