JPH023021B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection device for an engine, and in particular, it injects fuel sequentially into each cylinder of an engine using a fuel injection pump, and the timing of this injection is controlled by a drive device for the fuel injection pump. The present invention relates to an engine fuel injection device that is adjusted by a timer provided on the input side.

Conventionally, diesel engines have been provided with fuel injection pumps, which inject fuel into each cylinder of the engine in a predetermined order. In order to adjust the timing of this fuel injection,
A timer is provided on the input side of the camshaft of the fuel injection pump, and the timer adjusts the phase of the camshaft to change the injection timing. In general, when the timing of fuel injection by the fuel injection pump is advanced, that is, when the timer is advanced, the maximum combustion explosion pressure within the cylinder increases, so that the output of the engine increases. Conversely, if the timing of fuel injection is delayed, the maximum combustion explosion pressure will be lowered, resulting in a reduction in engine output.

From this point of view, it is better to inject fuel as early as possible, but engines are designed to withstand a certain maximum combustion explosion pressure, and this value should not be exceeded. Can not. Furthermore, engines usually include a plurality of cylinders, and there are variations in the maximum combustion and explosion pressures of each cylinder, and even if fuel is injected under the same conditions, the maximum combustion and explosion pressures in each cylinder are not necessarily equal. Therefore, in the past, the timer was adjusted to take into account the variation in maximum combustion explosion pressure among the cylinders and to allow a margin so that the largest value of the maximum combustion explosion pressures did not exceed the allowable pressure of the engine. Therefore, with such conventional engines, the output has sometimes been forced to be low.

The present invention has been made in view of these problems, and provides a fuel injection device for an engine that improves the output of the engine by making the most effective use of the pressure allowed by the engine. The purpose is to

In order to achieve the above object, the present invention sequentially injects fuel into a plurality of cylinders using a fuel injection pump, and sets the timing of this injection to a timer provided on the input side of the drive device of the fuel injection pump. In this apparatus, a pressure sensor is provided to detect the maximum combustion explosion pressure of each cylinder of the engine at each predetermined cycle, and the maximum value of the maximum combustion explosion pressure detected by these pressure sensors is provided. A hold means is provided for holding the value until a new maximum value is detected. Then, based on the maximum value held by the holding means, the maximum value of the maximum combustion explosion pressure detected via the pressure sensor and newly held by the holding means is set to be less than or equal to a permissible value and within the permissible value. The present invention is characterized in that means is provided for controlling the timer so that the timer approaches the timer.

With this configuration, even if there is variation between cylinders, the fuel injection timing can be controlled to be as advanced as possible depending on the state of the cylinder with the highest maximum combustion explosion pressure. Therefore, even if there are variations between cylinders, the fuel injection timing can be advanced as much as possible to achieve maximum combustion without any possibility that the maximum combustion explosion pressure will exceed the allowable value. It is possible to bring the explosion pressure close to an allowable value, and it is possible to improve the output without deteriorating the fuel efficiency and durability of the engine. FIG. 1 shows a diesel engine 1 according to this embodiment, and this engine 1 includes six cylinders 2. As shown in FIG. A piston 3 is slidably disposed within each of these cylinders 2, and an output is produced by the sliding movement of the piston 3 accompanying combustion and explosion. Furthermore, this engine 1 is equipped with a fuel injection pump 4 on the side thereof, and this pump 4 sequentially injects fuel into each cylinder 2 of the engine 1 in a predetermined order. A timer 6 is attached to the input side of the camshaft 5 of the fuel injection pump 4, and by adjusting the phase of the camshaft 5 using the timer 6, the timing of fuel injection by the fuel injection pump 4 is adjusted. is being done. Note that the timer 6 is driven by a gear 7 based on the output of the engine 1.
Further, the fuel injection pump 4 is provided with a mechanical governor 8 to adjust the load on the engine 1.

The timer 6 for adjusting the injection timing of the fuel injection pump 2 is provided with an actuator 9, and the actuator 9 is adapted to operate based on instructions from a microcomputer 10. To the microcomputer 10,
Rotation detection sensor 1 that detects rotation of engine 1
1. The detection outputs of a phase detection sensor 12 that detects the phase of the camshaft 5 and a load sensor 13 provided on the governor 8 are input. Therefore, the actuator 9 controls the microcomputer 1 according to the rotational speed and load of the engine 1.
0, and the output of the timer 6 is fed back to the microcomputer 10 by a phase detection sensor 12.

Furthermore, in this diesel engine 1,
Each cylinder 2 is provided with a pressure sensor 14, respectively. These pressure sensors 14 are connected to the cylinder 2
cylinder head 15 for closing the upper opening of
The maximum combustion explosion pressure within each cylinder 2 is detected. The detection outputs of these sensors 14 are input to a converter 16. The converter 16 is adapted to convert the maximum combustion explosion pressure of each cylinder 2 detected by the sensor 14 into an electrical signal. Furthermore, the converter 16 extracts the largest value among the maximum combustion explosion pressures of each of the six cylinders 2 and supplies this value to the sample hold circuit 17. The sample and hold circuit 17 is reset, for example, every cycle of the engine 1, and always supplies the microcomputer 10 with the largest value of the maximum combustion explosion pressures of each cylinder 2 of the engine 1.

In the above configuration, the injection timing of the fuel injection pump 4 for injecting fuel into the diesel engine 1 is adjusted by the timer 6, and the adjustment of the injection timing is performed by the rotation detection sensor 11 and the injection timing. Based on the detection of the load sensor 13, the microcomputer 10 and the actuator 9
It is now being carried out by Furthermore, according to this engine 1, the maximum combustion explosion pressure of each cylinder 2 is detected by the pressure sensor 14, and the maximum value is detected by the converter 16.
The sample and hold circuit 17 reads out the data and holds the sample and hold circuit 17. This held value is then stored in microcomputer 1.
The microcomputer 10 compares the maximum value of the maximum combustion explosion pressure of each cylinder 2 with the pressure allowed for the engine 1, and the maximum value above is input as the pressure allowed for the engine. The timer 6 is adjusted via the actuator 9 so that the pressure is below the threshold value and close to the permissible value.

Generally, the relationship between the timing of fuel injection by the fuel injection pump 4 and the maximum combustion explosion pressure in each cylinder 2 is as shown in FIG. Note that the engine rotation speed is used here as a parameter. As is clear from this graph, when the timing of injection by the fuel injection pump 4 becomes earlier, that is, when the phase of the timer 6 advances, the maximum combustion explosion pressure increases, and conversely, the phase of the timer 6 lags. If this happens, the maximum combustion explosion pressure will be lower. Therefore, by adjusting the injection timing of the fuel injection pump 4 using the timer 6, it becomes possible to control the maximum combustion explosion pressure in each cylinder 2 of the engine 1.

As mentioned above, in the engine 1, the largest value of the maximum combustion explosion pressures of each cylinder 2 is held, and the largest value held is below the engine's allowable pressure and approaches the allowable pressure. , microcomputer 1
Since the phase angle of the timer 6 is adjusted by the engine 0 and the actuator 9, it is possible to output the maximum output while maintaining the strength of the engine 1. Moreover, in this engine 1,
Since the timer 6 is adjusted according to the largest value of the maximum combustion explosion pressures of each cylinder, even if there is variation in the maximum combustion explosion pressure of each cylinder 2, the engine 1 will not be damaged. disappears.

As described above, the present invention provides each cylinder of an engine with a pressure sensor that detects the maximum combustion explosion pressure, and also provides a hold means that holds the largest value of the maximum combustion explosion pressure of each cylinder, The timer of the fuel injection pump is adjusted so that the largest value held is below the allowable pressure and approaches the allowable pressure. Therefore, according to the present invention, even if there are variations in the maximum combustion explosion pressure of each cylinder of the engine, it is possible to improve the output by utilizing the allowable pressure to the limit without damaging the engine.
It becomes possible to improve engine output without deteriorating fuel efficiency.

[Brief explanation of drawings]

FIG. 1 is a side view of an engine equipped with a fuel injection device according to an embodiment of the present invention, and FIG. 2 is a graph showing changes in maximum combustion explosion pressure with respect to the timing of fuel injection by the fuel injection pump of this engine. be. In addition, in the symbols used in the drawings, 1... Diesel engine, 2... Cylinder, 4... Fuel injection pump, 5... Camshaft, 6... Timer, 9
... Actuator 10 ... Microcomputer, 14 ... Pressure sensor, 16 ... Transducer, 17
...This is a sample and hold circuit.

Claims (1)

[Claims] 1. A device in which fuel is sequentially injected into a plurality of cylinders by a fuel injection pump, and the timing of this injection is adjusted by a timer provided on the input side of the drive device of the fuel injection pump, A pressure sensor that detects the maximum combustion explosion pressure of each cylinder of the engine at each predetermined cycle, and a maximum value of the maximum combustion explosion pressure detected by these pressure sensors until a new maximum value is detected. a holding means for holding, and a maximum value of the maximum combustion explosion pressure detected via the pressure sensor based on the maximum value held by the holding means and newly held by the holding means, such that the maximum value is below a permissible value; Moreover, a fuel injection device for an engine is provided with means for controlling the timer so that the timer approaches the permissible value.