JPH0211732B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronically controlled fuel injection device for an internal combustion engine, and particularly to a fuel injection device having a control device with a safety mechanism in case a rotation angle sensor fails.

Various electronically controlled fuel injection devices have been proposed in the past. The most important sensor in injection control is the engine rotation angle sensor. Most commonly, a so-called electromagnetic pickup is often used as this rotation angle sensor. Detection of the engine rotation angle is fundamental to control, and control is impossible without it. However, in the previous models, only one rotation angle sensor was provided, and coil disconnection,
Failures such as disconnection of the wire harness and poor contact of the connectors were not sufficiently considered, and only attention was paid to improving reliability at the manufacturing stage. Even with particularly high-grade equipment, measures were only taken to stop the engine in the event of a failure.

If there is no control logic in case of a failure, the engine will become uncontrollable due to some kind of failure, and the engine will go into an uncontrolled state, and if the conditions are bad, it will end up in a dangerous situation such as overrun. In addition, if the engine is of high quality and has a logic system that stops the engine, the first danger such as overrun can be avoided. If such a situation occurs, a secondary danger arises in that it is impossible to escape, run under one's own power, or secure pressure, which can become a serious problem. However, this measure was not considered at all.

The present invention provides for a crank position sensor installed in an engine and a control device installed when the rotation angle sensor is out of order and accurate rotation angle information that should be obtained based on the output of the rotation angle sensor cannot be obtained. The purpose of this invention is to approximately generate rotation angle information using a clock device, and based on this information, keep the deterioration of control performance to a compromised level and enable continuous operation, thereby solving the above problem.

FIG. 1 shows an example of the overall configuration of an electronically controlled hydraulically driven diesel injection device according to an embodiment of the present invention. In the figure, 1 is an injector, 2 is a high pressure source, 3 is a low pressure source, and 4 is a control device. The injector 1 includes a spool valve 5, a plunger 8, a piston 9, a nozzle 10, and first, second, and third
It consists of electromagnetic valves 11, 12, 13, a throttle 22, and a check valve 24, and the pressure sources 2, 3 are pumps 201,
301, relief valve 202, 302, filter 2
03, 303, pressure accumulators 204, 304, and oil (fuel) tanks 205, 305 constitute a normal constant oil pressure source. 16 is a fuel tank. The control device 4 is also connected to various sensors (FIG. 2) and to the three electromagnetic valves 11, 12, and 13.

FIG. 2 shows an example of the configuration of a six-cylinder engine equipped with a fuel injection device according to an embodiment of the present invention. engine 100
The spool valve 5, plunger 8, piston 9, nozzle 10, and solenoid valves 11 and 1 shown in FIG.
The engine 100 is equipped with an engine rotation angle sensor 101, a top mark sensor 102, and other sensors 103 to 110, and is connected to a control device 4. On the other hand, pressure piping from the hydraulic power sources 2 and 3 shown in FIG. The control device 4 is composed of a microcomputer and a solenoid valve drive circuit, and detects the state of the engine using various sensors and performs control according to a program.

To describe the operation of the system configured as described above, control signals are output from the control device 4 to the solenoid valves 11, 12, and 13 in accordance with information from various sensors. The spool valve 5 is actuated by the electromagnetic valves 11 and 12, thereby controlling the hydraulic pressure applied to the piston 9 that drives the plunger 8. The plunger 8 and piston 9 increase the hydraulic pressure supplied from the pressure source 2 and supply it to the nozzle 10 to perform a fuel injection operation. Fuel for injection is introduced from the hydraulic source 3 by opening and closing the solenoid valve 13 in accordance with the electric signal calculated and output by the control device 4, and by controlling the opening and closing time of the solenoid valve 13. The fuel injection amount is then controlled. At this time,
A throttle 22 is provided to reduce the rate of change in the injection amount with respect to time. The injection timing is controlled by operating the solenoid valve 11 in accordance with the electrical signal calculated and output by the control device 4, and by moving the spool valve 5, the timing for applying the hydraulic pressure from the pressure source 2 to the piston 9 is controlled. Let's change it. Strictly speaking, injection begins with a certain mechanical delay. Therefore, it can be controlled by the electrical signal.

As is clear from the above explanation, all injection operations such as injection amount and injection timing are controlled by electrical signals based on calculations of the control device, and crank position information is essential to operating each electromagnetic valve.
Since the injection device shown here as an example is already common and its operation is well known, further detailed explanation will be omitted.

Next, the method of calculation and control carried out by the control device 4 will be explained with reference to the flowchart of FIG. The control device 4 reads each sensor information at an optimal cycle (step 351) and constantly grasps the state of the engine. In this case, it is always determined whether or not the rotation angle sensor is normal based on the output signal of the rotation angle sensor 101, which is the most important of these pieces of information (step 352). For example, if the rotation angle sensor is an electromagnetic pickup, you can check the output amplitude range, check the level within the permissible frequency range, or check whether there is an impossible change by comparing with the previous value. Are known. If it is determined that the engine is normal, the engine speed is calculated from the rotation angle information obtained based on the output of the rotation angle sensor (step 353), and then this engine speed and the accelerator position obtained from the accelerator sensor 110 are calculated. calculates the optimum injection amount by adding corrections based on various pressures and temperatures (step 35).
4). Further, the optimum injection timing is calculated in the same manner (step 355). Based on this information, the operation timings of the solenoid valves 11, 12, 13 of the injector 1 are calculated (step 356).
Then, an operation control signal is output for each solenoid valve of each cylinder that matches the operation timing with respect to the rotational position of the engine known from the rotation angle information and the output signal of the top mark sensor 102 (step 357). The process returns to step 351 to read each sensor, and this loop is repeated to perform the operation. By the way, the rotation angle sensor 10
1 is determined to be abnormal, the control goes into a failure mode, and according to the present invention, processing for switching and changing information related to the rotation angle, specifically input switching for sensor outputs related to the rotation angle, or parameters and calculation formulas is performed. The flag controlling the change is rewritten (step 358). As a result, the control device 4
The rotation angle information created approximately is used, and the fuel injection control calculations are also performed according to this approximate rotation angle information, and the calculations and outputs are performed sequentially in steps 359 to 364, which are the same as in normal times. Execute and repeat the loop to continue operation. At this time, it is desirable to turn on the indicator lamp 111 to notify the operator of the abnormality in the rotation angle sensor 101.

Next, an example of a method for creating approximate rotation angle information in failure mode will be described. Rotation angle sensor 10
Strictly speaking, there is no way to know the crank angle position of the engine when 1 becomes abnormal. However, the top mark sensor 102 senses the engine rotation, albeit very roughly. Top mark sensor 102 detects the top dead center (TDC) of at least one cylinder and outputs a pulse corresponding to TDC at a period dependent on the engine speed. Paying attention to this point, the input signal from the rotation angle sensor 101 is switched to the signal from the top mark sensor 102, and the parameters and arithmetic expressions are changed to obtain approximate rotation angle information. Thereafter, based on this approximate rotation angle information (top mark sensor signal, changed parameters and calculation formulas, calculation results, etc.), calculations of engine rotational speed, injection amount, etc. are performed. To explain the engine speed calculation in step 359, for example, in a system equipped with the top mark sensor 102 only for the TDC of the first cylinder, this one pulse is output per 720 degrees of crank angle.
The period is measured within the control device. It is built into the control device 4. When the pulse frequency of the clock signal of the clock device is 1KHz, and if there are 120 clocks in one pulse period of the top mark sensor output, the engine rotation speed is 720°/360° x 60/1/1000 x 120 = 1000 r. pm. In addition, in the case of six cylinders as shown in Fig. 2, the output of the solenoid valve control signal is based on the output of the top mark sensor for the first cylinder, and the output of the top mark sensor is used as the reference for the output of the solenoid valve control signal for the other cylinders.
The TDC timing of other cylinders is estimated every clock from the cylinder TDC, and based on this, a solenoid valve control signal is output (step 363). Of course, this may not be dynamically correct, but it is accurate enough to withstand emergency operation when there are no severe load fluctuations or rotational speed fluctuations. Accuracy can be improved if statistical processing is programmed by using a microcomputer, which has developed significantly in recent years and whose processing speed has become faster, as a control device. However, in several experiments so far, rather than dynamically measuring and setting the timing including explosion fluctuations, in the case of a 6-cylinder engine as in the above example, 20 was obtained by calculating 120/6 = 20. Estimating the TDC timing on an average for each clock and calculating the output timing of the solenoid valve control signal on the average based on this provides better controllability, at least in systems with mechanical delays such as solenoid valves. Since the calculation is complicated, it is sufficient to not perform high-level processing such as the above-mentioned statistical processing.
Here, "on average" means that, depending on the above-mentioned fluctuations, the TDC timing may be estimated to be every 21 clocks or every 19 clocks, but this is averaged to every 20 clocks.

Next, the top mark sensor 102 detects each cylinder.
The present invention can also be applied to a system that outputs a pulse every TDC. In this case, one pulse period is a crank angle of 120° for a 6-cylinder engine, so one pulse period includes 20 clocks, so the engine speed is 120°/360° x 60/1/1000 x 20 = It can be calculated as 1000 rpm, and it goes without saying that this accuracy is higher than the above example of 2 revolutions and 1 pulse. Furthermore, in this case, the signal from the top mark sensor can be used as it is as the reference for outputting the solenoid valve control signal, so that the timing accuracy can be almost the same as in normal times.

By parallel processing the rotation angle detection using the top mark as described above during normal operation,
It is also clear that more precise abnormality diagnosis can be made.

From another point of view, it is of course possible to create a program using interrupts using the control flow shown in Figure 3 in the same way as a general method, and it is also possible to assemble these programs using analog circuits without using a digital computer. Of course, it is also possible, and it goes without saying that a combination thereof is also possible.

The switching/changing process related to the above rotation angle information can be performed by information selection (selection by switching the information storage address), but it can also be done by hardware in the input circuit, or even manually by the driver. You can also use it as In this case, it is necessary to stop the engine once.

Further, the clock pulses may be counted by configuring a hardware counter in the control device, but the clock pulses may also be counted by software of a microcomputer.

It is clear that the present invention can be applied to systems in which the type of injector, configuration and number of hydraulic power sources, hydraulic oil, number and types of sensors, sensing items, etc. shown in the embodiment are changed.

According to the present invention, when the rotation angle sensor becomes abnormal, engine operation is maintained by approximately calculating rotation angle information using the signal of the crank position sensor and the clock signal in the control device. It is possible to obtain excellent effects such as:

Further, according to the present invention, the complicated sequential operation of the injector can be realized with high precision.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing an example of a fuel injection device according to an embodiment of the present invention, and FIG. 2 is a diagram showing an example of the configuration of a six-cylinder engine equipped with the fuel injection device shown in FIG. FIG. 3 is a flowchart illustrating the operation of the control device included in the fuel injection system of FIG. 1. Explanation of symbols 1... Injector, 2, 3...
Pressure source, 4...control device, 5...spool valve, 1
0... Nozzle, 11, 12, 13... Solenoid valve.

Claims (1)

[Claims] 1. A rotation angle sensor that detects the rotation angle of an engine, a crank position sensor that detects a reference crank position of at least one cylinder of the engine and outputs a pulse signal corresponding to the reference crank position, and an engine. a control device that operates based on the output signals of these sensors and outputs a fuel injection control signal; and a control device that operates in accordance with the output signals of these sensors and outputs a fuel injection control signal; In the fuel injection device for an internal combustion engine, the control device includes a clock means for generating a clock signal at regular intervals in order to measure time by operating at least when the rotation angle sensor is abnormal. and when the rotation angle sensor becomes abnormal, the control device estimates pseudo information in place of the information from the rotation angle sensor based on the output signal of the crank position sensor and the clock signal, A fuel injection device for an internal combustion engine, which outputs a fuel injection control signal based on the fuel injection control signal. 2. In claim 1, the control device determines the output timing of the fuel injection control signal when the rotation angle sensor is abnormal based on the output signal of the crank position sensor, the clock signal, and the number of cylinders of the engine. A fuel injection device for an internal combustion engine characterized by calculating an average value for each cylinder.