JPS6253711B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention automatically searches for optimal ignition timing characteristics that provide high output and low fuel consumption over the entire operating range of a spark-ignition internal combustion engine. The present invention relates to a device for measuring.

[Conventional technology and its problems]

In general, there is an optimum ignition timing in a spark-ignition internal combustion engine that can maximize the engine's output and achieve a low fuel consumption rate. This varies depending on various conditions such as the turbulence state of the intake air mixture, charging efficiency, air-fuel ratio, atmospheric pressure, and the temperature of the engine and the intake air mixture. In other words, the pattern of optimal ignition timing characteristics obtained by actually measuring the intake pressure and engine speed while varying the intake pressure and engine speed is expressed as the vacuum related to the intake pressure. It is well known that the engine's ignition timing is controlled by setting a centrifugal advance mechanism and a centrifugal advance mechanism that is related to the rotational speed.

On the other hand, as is generally known, the average effective pressure (or engine output) and fuel consumption rate when changing the ignition timing are curves E and F shown in Figure 1, and any point E on curve E Since the point where the gradient at ′ becomes zero, that is, the point where the maximum value is taken, is the optimal ignition timing (MBT),
To measure the most suitable ignition timing characteristics for an internal combustion engine, set the engine to an operating condition with a desired intake pressure and rotation speed, and then manually shift the ignition timing in this operating condition until the output is maximized. The ignition timing, that is, the optimal ignition timing, is searched, and this search operation can be performed under any atmospheric conditions such as standard atmospheric conditions (atmospheric pressure 760 mmHg, temperature 20 degrees Celsius, humidity 60%), and engine rotation. While changing the number from the highest value to the lowest value every 25 to 50 equal intervals, the intake pressure is changed from the intake pressure at no load to the intake pressure at maximum load by about 10 minutes. The measurement must be performed for each of the 250 to 500 different operating conditions at different intervals, and each point must be plotted, so it takes a great deal of time to measure the optimal ignition timing over the engine's entire operating range. This was because it required a lot of work.

An object of the present invention is to provide a device that can automatically measure the optimal ignition timing in the entire operating range of an internal combustion engine.

[Means for solving problems]

For this reason, the present invention relates to a spark ignition system in a spark ignition internal combustion engine, and detects the internal cylinder pressure of the engine or the output of the engine at a certain crank angle position intermittently, and detects the engine output according to the difference in detection before and after that. An ignition timing control device that changes and controls ignition timing so that the average effective pressure or engine output is maximized; The apparatus includes an operation control device that maintains the rotation speed and intake pressure for a certain period of time, and adjusts the optimum ignition timing at that time in response to changing the rotation speed and intake pressure by the operation control device. The apparatus is equipped with a recording means that detects the optimum ignition timing and records the optimum ignition timing as a map using the rotational speed and intake pressure as parameters.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, reference numeral 1 indicates a spark ignition type internal combustion engine for measuring the optimum ignition timing corresponding to the intake pressure and rotation speed over the entire operating range. The engine 1 is installed in a measurement chamber (not shown) in which air pressure, temperature, and humidity are controlled by an air conditioning control device 2, and an output shaft 4 from a transmission 3 directly connected to the internal combustion engine 1. is connected to a dynamometer 5.

Reference numeral 6 refers to the throttle valve 8 for adjusting the amount of intake air in the intake passage 7 of the internal combustion engine 1 and the dynamometer 5, which arbitrarily sets the intake pressure and rotation speed, and controls the set intake pressure. and an operation control device that maintains the rotation speed only for a certain period of time.

Reference numeral 9 indicates an operating state in which intake pressure and rotation speed are arbitrarily combined over the entire operating range of the internal combustion engine 1;
For example, as mentioned above, while changing the rotation speed from the highest value to the lowest value at every 25 to 50 equal intervals, the intake pressure can be changed from the intake pressure at no load to the intake pressure at maximum load. This figure shows a program controller that sequentially instructs the operation control device 6 to operate in a total of 250 to 500 different operating states, changing the period up to 10 at equal intervals.

Reference numeral 10 indicates an optimum ignition timing search device, and the optimum ignition timing search device 10 includes an ignition timing control device 11, a storage circuit 12, and a central control device 13.

The ignition timing control device 11 is related to the ignition system in the internal combustion engine 1, as will be described in detail later,
In any operating state set by the program controller 9 and the operation control device 6, the ignition timing at that time is automatically controlled to the optimum ignition timing for that operating state, and the memory circuit 12 includes: The optimal ignition timing obtained by the ignition timing control device 11 is temporarily stored together with the operating state at that time, that is, the intake pressure and rotation speed. Furthermore, the central control device 13 controls the program controller 9 to set the operating state of the internal combustion engine 1 to a certain combination, and then the ignition timing control device 11 to control the ignition timing to the optimal ignition timing at that time, When this is stored in the memory circuit 12, a command is issued to the program controller 9 to move to the next operating state.

The air conditioning control device 2 includes the central control device 13
The atmospheric pressure, temperature, and humidity inside the measurement chamber can be controlled arbitrarily according to instructions from the operator.

And the ignition timing control device 1 used here
1 is configured as follows.

That is, the average effective pressure (or output of the internal combustion engine) when the ignition timing is changed in the spark-ignition internal combustion engine 1 becomes the curve E shown in FIG. By shifting the ignition timing to the retard direction in the upper left region of the curve E in the advance direction, the curve E
The curve E can be approached to the point where the slope becomes zero, that is, the optimum ignition timing, while the curve E is determined in relation to the combustion pressure that accurately reflects the combustion state in the internal combustion engine, that is, the in-cylinder pressure. This is then used to control the ignition timing to the optimum ignition timing.

More specifically, since the explosion interval in each cylinder of the internal combustion engine 1 is an extremely short time interval, the combustion state at the n-th explosion time in a certain cylinder and the combustion state at the n-1th explosion time are different. can be considered almost the same (where n is a natural number).
Therefore, the cylinder pressure P of a certain cylinder is detected, for example, at a certain appropriate crank angle Q position, and the n-th cylinder pressure Pn and the (n-1)th cylinder pressure P _{o are} detected.
_-1 (Pn-P _o-1 = ΔP), and
When ΔP>0 when the n-th ignition timing (θig) is advanced compared to the n-th ignition timing (θig), or
The n-th ignition timing (θ
When ΔP<0 in the case where ignition timing (θig) is retarded, the n+1st ignition timing (θig) is controlled in the advance direction, and conversely, the nth ignition timing (θig) is When ΔP<0 when the ignition timing (θig) is advanced, or when ΔP>0 when the n-th ignition timing (θig) is retarded compared to the n-1st, the n+1st ignition timing (θig) is advanced. The ignition timing (θig) of the engine is automatically controlled in a retarded direction to bring it closer to the optimum ignition timing.

An embodiment of this ignition timing control device 11 is shown in FIG. 3 in terms of a block diagram. Here, numeral 14 is a pressure sensor such as a piezoelectric element for detecting the cylinder pressure P, numeral 15 is a signal processing device from the pressure sensor 14, and numeral 16 is
1 is a comparator, 17 is an ignition timing control circuit, and 1 is a comparator.
8 is an ignition circuit, 19 is an ignition coil, 20 is a spark plug, 21 is a crank angle signal generator, 22 is an ignition reference signal generator, and 23 is a knocking analyzer.

The signal processing device 15 intermittently detects the cylinder pressure P at a constant crank angle (Q) using a pulse signal from the crank angle signal generator 21, and inputs the detected value to the comparator 16. This signal processing device 15 performs necessary processing such as averaging or integrating the cylinder pressure P in appropriate sections during the explosion stroke, and performs necessary processing on the cylinder pressure P in appropriate sections during the explosion stroke.
6 inputs may also be used. The comparator 16 compares and calculates the signal from the signal processing device 15 with the values before and after it, and issues an advanced or retarded ignition timing signal to the ignition timing control circuit 17 from two output terminals 16a and 16b. Then, from the comparator 16, the nth
- When the first ignition timing signal issued is an advance signal, the difference in cylinder pressure between the n-th and (n-1)th cylinders detected by the signal processing device 15 (Pn- _{Po- 1} = ΔP) is negative (ΔP < 0), in other words, when the cylinder pressure has decreased from the previous time,
Retard signal from the other output terminal 16b, ΔP>0
In other words, when the cylinder pressure increases from the previous time, the advance angle signal is sent from one output terminal 16a.
When ΔP=0, in other words, when there is no change in the cylinder internal pressure, a stop signal is issued, and when the ignition timing signal issued from the n-1st ignition timing signal from the comparator 16 is a retard signal. , when ΔP<0 and the cylinder pressure tends to decrease, an advance angle signal is sent from one output terminal 16a, and when ΔP>0
When the cylinder pressure tends to increase, a retard signal is generated from the other output terminal 16b, and when ΔP=0, a stop signal is generated.

The ignition timing control circuit 17 includes the comparator 16
An advance signal from one output terminal 16a of the comparator 16 is used to advance the ignition timing by an appropriate angle α (for example, 1 to 3 degrees), and a retard signal is sent from the other output terminal 16b of the comparator 16. The ignition timing is appropriately controlled to be retarded by an angle β (for example, 1 to 3 degrees). At this time, the appropriate angles α and β are
When the absolute value of ΔP determined by the signal processing device 15 becomes smaller than a certain value, that is, when it approaches the optimum ignition timing, the advance angle amount α or the retard angle amount β is decreased to reach the optimum ignition timing. It is also possible to improve the convergence to the ignition timing.

In this way, the ignition timing control circuit 17 maintains the operation of shifting the ignition timing in the advance direction while the advance signal from one output terminal 16a of the comparator 16 is input thereto. As a result, the average effective pressure increases, and when this reaches its maximum value, that is, when the ignition timing reaches the optimum ignition timing, the ignition timing advance control stops, and conversely, the comparator 16
The ignition timing is retarded by the retard signal from the other output terminal 16b of the The retard control stops.

Further, the ignition timing control circuit 17 is associated with an ignition timing signal generator 22, and controls the ignition timing to an arbitrary angular position (for example, top dead center) based on a signal from the ignition timing signal generator 22 when starting the engine. Previous 20
The knocking analyzer 23 is configured to improve the startability of the engine by setting the pressure waveform of the cylinder pressure P input through the signal processing device 15 to If the ignition timing is likely to change (for example, if a slight knock occurs), this is analyzed and detected, a signal is sent to the comparator 16, and the output from the signal processing device 15 is sent to the ignition timing control circuit 17. Regardless of the signal, a retard signal is given priority, and if knocking is about to occur, the ignition timing is forcibly controlled to the retard side until there is no knocking, and the ignition timing is It is possible to control the ignition timing so that it approaches the optimum ignition timing under conditions where no ignition occurs.

FIG. 4 shows the signal processing device 15 and the comparator 16.
This is a flowchart of an example of a program for operating the arithmetic processing unit of a microcomputer consisting of the ignition timing control circuit 17 and the like, and in this flowchart, P is the cylinder pressure (or engine output), θ is the ignition timing, n represents a natural number, and θ
₀ and _P0 indicate the initial values of the ignition timing and cylinder pressure (or engine output), respectively, and S indicates whether the previous (n-1th) ignition timing was advanced or retarded. When S=1, it indicates an advance angle, and when S=0, it indicates a retard angle. α and β are 1
This indicates the amount of advance and retardation per cycle, and the relationship is α≧β.

While the optimum ignition timing (MBT) detected under one operating state in this way and the operating state at that time, that is, the intake pressure B and the rotational speed N, are temporarily stored in the memory circuit 12, In response to instructions from the program controller 9, the optimal ignition timing under different operating conditions is stored together with the intake pressure and rotational speed at that time for the entire operating range of the internal combustion engine 1.

The data stored in the storage circuit 12 is controlled by the central controller 13.
MBT map chart 25 output to the blotter 24, with the rotation speed N on the horizontal axis and the optimum ignition timing (MBT) on the vertical axis, with intake pressure B and rotation speed N as parameters.
.

In this case, the optimal ignition timing may be displayed using the intake pressure B and the rotational speed N as parameters, and may also be stored as a map on a magnetic tape. When detecting the timing, a case has been shown in which the cylinder pressure P is measured in order to utilize the average effective pressure curve E, but the output curve in an internal combustion engine is similar to the average effective pressure curve E. Therefore, the output of the internal combustion engine may be measured by the dynamometer 5, and the above-mentioned control may be performed in accordance with this measurement.

[Action/effect of the invention]

As described above, according to the configuration of the present invention, the spark ignition internal combustion engine is maintained in an operating state corresponding to an arbitrary intake pressure and rotational speed, while the cylinder pressure or output is maximized in this operating state. The ignition timing is shifted to the optimal ignition timing, and this is done for the entire operating range of the internal combustion engine. can be recorded in the entire operating range of the internal combustion engine.
It is possible to accurately and reliably detect the optimal ignition timing that includes all the variable factors that affect combustion in an internal combustion engine, and it can also be done by automatically changing the operating state of the internal combustion engine. Therefore, the optimum ignition timing can be detected quickly and fully automatically.

Furthermore, the present invention measures the optimal ignition timing for the entire operating range of an internal combustion engine as a map using intake pressure and rotational speed as parameters, and this map is based on the vacuum advance mechanism and centrifugal advance mechanism described above. Since it can be used as is when setting the advance angle characteristics in the advance angle mechanism, the advance angle characteristics in the vacuum type advance angle mechanism and the centrifugal type advance angle mechanism can be set.
It also has the effect of being extremely simple and accurate.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a diagram showing the relationship between ignition timing, average effective pressure, and fuel consumption rate, FIG. 2 is a block diagram of the measuring device, and FIG. 3 is a diagram of the ignition timing control device. The block diagram, FIG. 4, is a flowchart of the ignition timing control system. DESCRIPTION OF SYMBOLS 1... Internal combustion engine, 5... Dynamometer, 6... Operation control device, 9... Program controller, 10...
...Optimum ignition timing search device, 11...Ignition timing control device, 12...Storage circuit, 13...Central control device, 12...Air conditioning control device, 24...X-Y plotter.

Claims (1)

[Claims] 1 In connection with the spark ignition system in a spark-ignition internal combustion engine, the engine cylinder pressure or engine output is intermittently detected at a certain crank angle position, and the average effective pressure or engine output is determined according to the difference in detection before and after that. An ignition timing control device that changes and controls the ignition timing so that the output is maximized; is provided with an operation control device that maintains the same for a certain period of time, and
The optimum ignition timing at that time is detected as the rotational speed and the intake pressure are changed by the operation control device, and the optimum ignition timing is recorded as a map using the rotational speed and the intake pressure as parameters. 1. An apparatus for measuring optimal ignition timing in a spark-ignition internal combustion engine, characterized in that it is equipped with a recording means according to the invention.