JP2692184B2 - Engine air supply - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air supply device for an engine, and more particularly to an air supply device suitable for compensating for a delay in air supply during acceleration and preventing incomplete fuel.

[Prior Art] Conventionally, in an automobile engine, in particular, in a turbocharged engine equipped with an exhaust turbine type turbocharger, black smoke is instantaneously emitted when the accelerator is suddenly stepped on for acceleration. . The reason for this is that when the accelerator is stepped on for acceleration, the lever of the injection pump is pulled by this, and the fuel injection amount increases, but the intake air amount does not immediately increase due to the delay in the rotation increase of the turbocharger, etc. It is thought to be caused by this. That is, instantaneously,
The amount of fuel injection is too large for the intake air amount,
As a result, black smoke is emitted. On the other hand, for example, ceramics are used for the rotor of the turbocharger to reduce the weight and reduce the delay in rotation increase, but the improvement by this is not sufficient.
Further, it is possible to prevent the black smoke from being generated by suppressing the maximum injection amount in the low rotation speed region in the fuel injection characteristic of the injection pump, but as a result, the engine output at low speed is reduced.

On the other hand, a pressure vessel connected to an air pump linked to the engine is provided, and a compressed air supply valve for injecting compressed air stored in advance in the pressure vessel is provided in the intake passage downstream of the throttle valve. An engine air supply device has been proposed in which the engine is opened and the air amount is increased according to the opening degree and the opening speed of the throttle valve (actual opening Sho 58-108249). According to this, the delay of the air supply during the transient operation is compensated for by the compressed air injected from the compressed air supply, and the temporary fluctuation of the air-fuel ratio is prevented.

[Problems to be Solved by the Invention] However, in the above air supply device, the compressed air pressure in the pressure vessel is always kept constant by the pressure regulating valve provided in the middle of the air escape pipe from the pressure vessel to the air cleaner. It is kept. Therefore, when the pressure in the cylinder of the engine fluctuates, the valve opening period for supplying compressed air deviates from the optimum value only by controlling the valve opening of the compressed air supply valve according to the opening degree and the opening speed of the throttle valve. I will end up. That is, if the valve opening period is too short, generation of black smoke, that is, harmful emissions such as unburned HC increases, and conversely, if it is too long, the cylinder pressure becomes too high, which causes problems such as noise and seizure.

An object of the present invention is to provide an air supply device for an engine capable of constantly supplying an appropriate amount of compressed air from both sides of generation of black smoke and in-cylinder pressure.

[Means for Solving the Problems] An engine air supply device of the present invention is an air guiding system for introducing compressed air in a pressure vessel to the vicinity of an intake valve based on signals from an engine speed sensor and an accelerator sensor during an intake stroke during engine acceleration. Control means for determining the basic opening period of the solenoid valve in the passage, and correction means for correcting the basic opening period by the signals from the pressure sensors of the air passage and the pressure vessel to make the amount of compressed air constant It is configured by.

[Operation] The solenoid valve is opened during the intake stroke at the time of acceleration to guide the compressed air from the pressure vessel to the vicinity of the intake valve of the cylinder. In this case, the control means determines the basic valve opening period from the engine speed and the accelerator opening degree, and the correction means determines the result depending on the difficulty level of the air supply into the cylinder which changes depending on the values of the air passage pressure and the pressure vessel pressure. The basic valve opening period is increased / decreased so that the amount of compressed air supplied becomes constant. As a result, the proper air supply amount, which was provisionally defined by the basic valve opening period to prevent the emission of black smoke and to prevent the cylinder pressure of the engine from becoming too high, does not fluctuate, and always matches the fuel injection amount during acceleration. Compressed air is supplied.

[Examples] The present invention will be described below with reference to the illustrated examples.

In FIGS. 1 and 2, 1 is a 4-cylinder diesel engine, 2 is an intake manifold (intake passage) connected to each cylinder of the engine 1, and 3 is an air tank (pressure vessel) connected to a compressor 4. . Compressor 4
Is driven by a belt 7 wound between the engine crankshaft 5 and a crank pulley 6, and the air tank 3 is always kept at an appropriate pressure by the compressor 4.

A number of compressed air supply conduits (air passages) 8 corresponding to the number of cylinders are drawn from the air tank 3, and are connected to the most downstream portion of the intake manifold 2 for each cylinder. By forming the pressurized air ejection port of the air passage from the air tank 3 near the intake valve 22 of each cylinder in this way, the loss in introducing air into the cylinder 23 can be minimized. As shown in FIG. 2, one electromagnetic solenoid valve 9 is provided in the middle of each of the compressed air supply conduits 8 so that the compressed air supply conduits 8 can be independently shut off or communicated with each other. It is like this.

10 is a controller with a built-in microprocessor that controls the on / off of each solenoid valve 9.
10, the compressed air of the air compressor 3 is supplied from the intake manifold 2 to the engine 1 in an appropriate amount in accordance with the intake stroke of each cylinder during acceleration. For this purpose, the accelerator opening APP from the stepped stroke of the accelerator pedal 12
An accelerator sensor 11 that measures the engine speed, a top dead center sensor 13 that functions as an engine speed sensor that measures the engine speed N,
A crank angle sensor 14 for determining the opening / closing timing of the solenoid valve 9, a negative pressure sensor 15 for measuring the pressure P1 of the intake manifold 2, and a pressure sensor 16 for measuring the pressure P2 in the air tank 3 are provided. The top dead center sensor 13 has two crankshafts 5.
A 1-pulse signal is output by rotation, and the crank angle sensor 14
Is 1 pulse per 1 degree of rotation of crankshaft 5 (36
0 pulse) signal is output.

FIG. 3 shows the timing of the opening period of each intake valve 17 of the engine 1 and the opening / closing timing of the solenoid valve 9 during that period.

(1) Whether or not to operate the solenoid valve 9 is determined by signals from the accelerator sensor 11 and the top dead center sensor (engine speed sensor) 13. The operating condition is basically the case where the measured accelerator opening degree APP is larger than a predetermined value and the engine speed N is within a predetermined range.

(2) The opening time and closing time of the solenoid valve 9 can be determined by the number of output pulses of the crank angle sensor 14 from the time when the output pulse is generated in the top dead center sensor 13.
When the solenoid valve 9 is actually opened and closed, that is, after the signal of the top dead center sensor 13 is detected, how many output pulses of the crank angle sensor 14 will open the solenoid valve 9 and how many times it will be closed, In association with the number of output pulses of the crank angle sensor 14, a plurality of types of data are stored in advance in the memory for each cylinder. When the condition of (1) above is satisfied and the solenoid valve 9 is to be operated, the accelerator opening APP and the engine speed N at that time
Appropriate data is selected from these data groups, and each solenoid valve 9 is turned on / off based on the data based on the signal from the top dead center sensor signal and the signal from the crank angle sensor 14.

Fig. 4 shows the optimum valve opening period for the solenoid valve 9
Indicates Tx.

The horizontal axis of FIG. 4 shows the valve opening period T as the pulse generation time of the top dead center sensor as the valve opening period T = 0, and the vertical axis shows the black smoke and the cylinder pressure. As can be seen from the curve A, when the opening period T of the solenoid valve 9 becomes shorter than T1,
The compressed air supplied from the air tank 3 becomes insufficient, and harmful emissions such as black smoke, that is, unburned HC increase beyond the allowable limit. On the contrary, as can be seen from the curve B, when the opening period T of the solenoid valve 9 is longer than T2, the compressed air supplied from the air tank 3 becomes too much, which in turn increases the cylinder pressure, which causes noise and noise. It causes problems such as image sticking. Therefore, the optimum valve opening period Tx must be between the above-mentioned T1 and T2 where the generation of black smoke is small and the cylinder pressure is not so high.

In this way, the optimum valve opening period Tx for the solenoid valve 9 is determined from the relationship between the cylinder pressure and the black smoke. However, this optimum valve opening period Tx is premised on that the compressed air supplied from the air tank 3 does not fluctuate per unit time. Therefore, for example, when the pressure in the cylinder of the engine fluctuates and the difference between the pressure in the air tank and the pressure in the cylinder becomes small, the compressed air supply becomes insufficient, and when the pressure difference becomes large, the compression Excessive air supply. Therefore, in actuality, in order to maintain the valve opening period for supplying compressed air at the optimum valve opening period Tx, it is necessary to correct the time lag from the optimum value. Controller 10 above
Is for determining the optimum valve opening period Tx as a result of taking this correction into consideration and controlling the opening / closing of each solenoid valve 9.

Now, referring to FIG. 5, the controller 10 includes an AD converter 16 for converting an analog signal from the accelerator sensor 11, the pressure sensor 16 and the negative pressure sensor 15 into a digital signal, and a unit time from the top dead center sensor 13. Counter that counts the number of pulses per hit and measures the engine speed N
18, a counter 19 for counting the number of pulses (1 pulse / 1 degree) from the crank angle sensor 14, a CPU 20, a memory ROM, and a microprocessor mainly including an output port 21 as memory ROM and RAM.

The CPU 20 calculates according to the control program stored in the memory ROM, based on the data of each parameter obtained from the AD converter 17 and the counters 18 and 19 and the data stored in advance in the memory RAM, and optimizes each solenoid valve 9 described above. Determine the optimum valve opening period length Tx of each solenoid valve 9 based on the center T01 (FIG. 4) of the valve opening period Tx,
Output the signal corresponding to this optimal valve opening period length Tx port 19
Is output to each solenoid valve 9 individually.

As will be described in detail, the memory RAM stores in advance various data to be determined by the above parameters and taken out. The first is engine speed N and accelerator opening APP
Is a data group relating to the basic valve opening period T0 that should be determined from, and the second is data regarding the correction value K1 that should be increased or decreased according to the actual intake manifold pressure P1. Basic valve opening period is the actual air tank pressure
It is data about the correction value K2 that should be increased or decreased according to P2.
Here, the intake manifold pressure P1 is a value obtained by previously converting the relationship between the intake manifold pressure P1 and the known cylinder pressure of the engine, which is representative of the cylinder pressure.

Next, referring to FIG. 6, a method of creating the optimum valve opening period Tx will be described.

In FIG. 6, the controller 10 reads data of each parameter obtained from the AD converter 17 and the counter 18, that is, engine speed N, accelerator opening APP, intake manifold internal pressure P1, and air tank 3 internal pressure P2 ( Step). Then, from the values of the engine speed N and the accelerator opening APP measured at the present time, first,
One of the data groups relating to the basic valve opening period T0 stored in the memory RAM is selected (step). This corresponds to selecting one of a plurality of curve groups drawn for the same valve opening degree in the step of FIG. If the corresponding data does not exist, it is not the case where the above-mentioned accelerator opening APP is larger than a predetermined value and the engine speed N is within a predetermined range, so that nothing is returned.

When the data of the corresponding basic valve opening period T0 exists, the correction calculation is performed based on the correction value K1 data stored in advance in the memory RAM based on the intake manifold internal pressure P1. That is, the correction value K1 at the standard set pressure P10 is set to K1.
= 1, and if the intake manifold internal pressure P1 is higher than this, it takes time to supply compressed air, so the correction value K1 is increased by that amount, and the optimum valve opening period of each solenoid valve 9 is increased. Increase the length Tx. Further, when the intake manifold internal pressure P1 is lower than the standard set pressure 10, the correction value K1 is reduced by that amount, and the optimum valve opening period length Tx of each solenoid valve 9 is shortened ( Step).

Next, based on the pressure P2 in the air tank 3, the memory RA
Correction calculation is performed based on the correction value K2 data stored in M in advance. That is, the correction value K2 at the standard set pressure P20
Is set to K2 = 1, and when the air tank internal pressure P2 is higher than this, the time required to supply the compressed air may be shortened accordingly. Therefore, the correction value K2 is reduced by that amount, and the solenoid valve 9 Shorten the optimum valve opening period length Tx. Further, when the intake manifold internal pressure P1 is lower than the standard set pressure 20, the correction value K2 is increased by that amount, and the optimum valve opening period length Tx of each solenoid valve 9 is lengthened (step). .

Finally, as shown in the step, the controller 10 determines the optimum valve opening period Tx according to the function shown by the following equation, and individually outputs a signal corresponding to this to each solenoid valve 9.

Tx = T0 (N, APP) K1K2 Thus, at the time of engine acceleration, an appropriate amount of compressed air commensurate with the fuel injection amount is given to each cylinder from the intake manifold as an appropriate time width within the intake stroke. Generation of smoke and excessively high internal pressure of each cylinder of the engine can be suppressed.

[Advantages of the Invention] As described above, according to the present invention, compressed air corresponding to the fuel injection amount is supplied to supplement intake air according to the degree of difficulty of air supply into the cylinder during acceleration, thus preventing the emission of black smoke. At the same time, the pressure inside each cylinder of the engine can be suppressed from being too high.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing its air supply system, FIG. 3 is a timing chart of valve opening / closing, and FIG. 4 is black smoke and cylinder interior of the present invention. FIG. 5 is a diagram showing an optimum valve opening period in relation to pressure, FIG. 5 is a block diagram of the controller, and FIG. 6 is a flow diagram showing control contents of the controller. In the figure, 1 is an engine, 2 is an intake manifold, 3 is an air tank, 8 is a compressed air supply line, 9 is a solenoid valve, and 10 is a solenoid valve.
A controller, 11 is an accelerator sensor, 13 is a top dead center sensor, 14 is a crank angle sensor, 15 is a negative pressure sensor, and 16 is a pressure sensor.

Claims (1)

(57) [Claims] 1. A control means for determining a basic opening period of an electromagnetic valve in an air passage for guiding compressed air in a pressure vessel to the vicinity of an intake valve based on signals from an engine speed sensor and an accelerator sensor during an intake stroke during engine acceleration. An air supply device for an engine, comprising: and a correction unit that corrects a basic valve opening period by a signal from each pressure sensor of an air passage and a pressure container to make a supply amount of compressed air constant.