JPH033064B2 - - Google Patents

Description

Detailed Description of the Invention The present invention uses a valve that is operated by an electric command to control the timing and period of fuel injection in a pattern according to the engine speed, and the amount of fuel injection is controlled by the injection pressure. The present invention relates to a speed governor of a fuel injection control device for a diesel engine that controls the amount of fuel supplied.

Conventional fuel injection control devices for diesel engines often use a reciprocating motion function such as a plunger, but when such a motion mechanism is driven by the engine's crankshaft, the reciprocating motion itself is controlled independently of the engine speed. It is impossible to do so, and it is not easy to control by setting a phase difference with the engine speed. Therefore, it is necessary to control the fuel injection pressure and timing by varying the fuel injection pressure and timing in order to save energy and reduce pollution. It was difficult.

In order to carry out such complex fuel injection control, the timing and duration of fuel injection must be controlled by patterns using valves that are operated by electrical commands, and the amount of fuel injection must be controlled independently of this. Alternatively, there is a method of controlling by the related injection pressure, an example of which is disclosed in Japanese Patent Application No. 54-160286 (Japanese Unexamined Patent Publication No. 56-83530). However, in the above example, nothing is disclosed about the speed regulating function, which is essential for large and medium-sized diesel engines.

The present invention provides a fuel injection control device for a diesel engine that controls the amount of fuel supplied by controlling the injection pressure or both the injection pressure and the injection period. By directly applying the fuel supply control function that the engine has, that is, controlling the injection pressure or both the injection pressure and the injection period, it is possible to easily control the engine speed, regulate the engine speed, maintain the idling speed, and stall the engine. The purpose is to prevent over-rotation or, conversely, to prevent runaway.

Conventional methods for controlling the amount of fuel supplied by controlling the injection pressure or both the injection pressure and the injection period vary depending on the type of engine. In the examples described below, for ease of explanation, the injection period is constant regardless of the size of the fuel injector or engine speed, the fuel injection amount is controlled by increasing or decreasing the injection pressure, and the fuel injection starts. The timing of termination shall become earlier as the engine speed increases. FIGS. 1 and 2 show the relationship between the fuel injection period, injection start and end timing, injection pressure (fuel injection amount), and engine speed using such a method.

In Fig. 1, 1 indicates the fuel injection start point, and 2 indicates the end point.As shown in the figure, the start and end points rise in proportion to the engine speed, but the injection period (timing length) relative to the crank angle ) is constant as described above, and the injection period shown between the start point 3 and the end point 4 at the lowest rotation speed and the injection period shown between the start point 5 and the end point 6 at the highest rotation speed are the crank It is constant when viewed from an angle (however, time is different). When injection is performed at such timing, an example of pressure change when the same fuel is injected into the engine is represented by a pattern as shown in FIG. In the figure, curve 8 is a pattern at the so-called high injection command when a large number of fuel injections are performed.Injection is performed at low pressure at the lowest rotational speed, but if the pressure does not increase as the rotational speed increases. No. This is because the injection period is constant as shown in Figure 1, but this is constant with respect to the crank angle, and the required injection time is reduced in proportion to the increase in rotational speed, and within the thus reduced injection time. This is because, in order to inject the same amount of fuel, the injection pressure must be increased as shown in the figure. Curve 9 shows the same pattern when a lower amount of fuel is injected than curve 8. In order to control the fuel injection amount using this method, it is necessary to conduct tests in advance, create a pressure pattern group as shown in Figure 2 corresponding to the fuel to be injected, and perform pressure control based on this. become.

In addition, when the timing and period of fuel injection are performed in a fixed pattern and the injection amount is controlled by pressure, the fuel injection timing increases in proportion to the rotation speed, and the period is determined in terms of the crank angle. As I said, this is just one example. That is,
As mentioned at the beginning, the pattern that indicates the timing of fuel injection is not limited to this, and if the relationship between the timing of fuel injection and the rotational speed is constant, the corresponding predetermined amount of fuel can be applied to the injection pressure. Since the pressure pattern group required to inject fuel is also determined, it is only necessary to control the injection pressure according to that pattern.By using such a method, it is possible to implement a variety of fuel injection control methods other than those shown in this figure. It is.

This method can also be used to implement speed governing control by adding maximum and minimum speed governing functions to the fuel injection control device of a diesel engine that controls the fuel injection amount. By making the fuel injection pressure variable according to the method, fuel control can be performed, and thus the engine speed can be controlled.

Specifically, when the engine is overloaded and there is a risk that the engine will stop due to the externally commanded fuel injection amount, that is, when the engine rotation speed falls below a certain rotation speed (for example, the minimum rotation speed). In such a case, regardless of the commanded fuel injection amount from the outside (this command is performed using a pressure value in this fuel injection control device), the system will automatically stop the engine in response to the decrease in rotational speed , the fuel injection pressure is increased according to a predetermined pattern, and the fuel injection amount is increased to maintain engine rotation. If there is a risk of combustion, etc., the fuel injection pressure is lowered according to a predetermined pattern depending on the excess rate, thereby reducing the amount of fuel injected and preventing the engine from overspeeding. do it.

If the engine speed governor is controlled by such a method, it can be applied to the fuel injection control device described above without using the complex centrifugal governor, which has been widely used for a long time. By simply adding elements, it is possible to provide maximum and minimum rotational speed regulating functions.

The first embodiment of the present invention embodies the maximum/minimum rotational speed regulating function based on such a method, and the injection pressure pattern diagram shown in FIG.
This will be explained using the block diagram shown in FIG.

In Fig. 2, it is assumed that the engine is being operated under a certain amount of fuel injection from the outside and the injection pressure is as shown by curve 9. If the engine speed is gradually lowered and finally reaches the lowest rotational speed, and the commanded fuel injection amount is maintained, there is a risk that the engine will stop. In such a case, if the fuel injection amount is increased from this vicinity by increasing the injection pressure in the pattern shown by curve 51 as the engine speed decreases,
The amount of fuel injected into the engine increases dramatically as the engine cools down. This is because, as the engine speed decreases, if fuel injection is performed with a constant fuel injection period in terms of crank angle as shown in Figure 1, the time required for fuel injection will decrease as the engine speed decreases. This is because, in addition to this, the injection pressure increases, and as the engine decreases, the fuel injection amount increases rapidly due to the synergistic effect of both factors, that is, increases in injection time and injection pressure. Therefore, for the fuel injection pressure pattern shown by curve 51, the most preferable type is selected through testing etc. in advance in order to smoothly ensure the minimum engine speed, and if fuel injection is performed according to the pattern thus selected, For example, when there is an abnormal decrease in the engine speed, the fuel injection amount increases regardless of the command pattern 9 indicating the fuel injection amount from the outside,
As a result, the engine rotational torque also increases, and engine stoppage due to overload can be avoided.

When the engine is operated with a high fuel injection amount command, for example, the injection pressure will change to the curve 8 shown in Fig. 2.
Even when the engine rotation speed is carried out according to the pattern shown in , if the engine speed drops below the minimum rotation speed, it is sufficient to prevent the engine speed from decreasing by shifting to the above-mentioned curve 51. If necessary, a pattern shown by another curve 51' different from the curve 51 may be used. However, which method to use can be selected depending on the type of engine, etc., but the essence of the present invention is that when the engine speed decreases due to overload etc. Regardless, the predetermined injection pressure is shifted to a bank that increases as the engine speed decreases, thereby increasing fuel injection and thus maintaining the engine speed near the minimum rotation speed. The idea of doing so is the same.

Next, when the engine injects fuel according to the pattern shown by curve 9 in Fig. 2, and when the engine speed reaches near the maximum speed due to light load, the pattern shown by curve 52 will be applied based on the same concept. By shifting the injection pressure, the fuel injection amount can be reduced regardless of external commands, thereby preventing the engine from running. In this case, the pattern to be adopted is the same as that at normal rotation. A pattern indicating the injection pressure, for example, may be determined separately for curves 8 and 9 in FIG. 2, and in the case of this embodiment, the pattern indicated by 52' may be used.

Based on the above-mentioned concept, the third section describes a specific example in which the engine injects fuel with a specific injection pressure pattern within a specific rotation speed range, regardless of the fuel injection command from the outside. Let me explain this while quoting the diagram.

FIG. 3 is a block diagram showing an example for realizing the first embodiment, in which a tachometer TG and an angle detector TD for detecting the crank angle attached to a two-cycle diesel engine EN are connected to the engine EN.
The rotation speed information and the crank angle, that is, information indicating the stroke of the engine are output to an injection timing detector 21 that includes a known pattern generator and a comparator. The detector 21 has a built-in pattern with the same function as that described in FIG. When the fuel injection start point corresponding to the current engine speed is reached in each cycle, this is detected and an operation command is issued to the high speed switch SW made of a known semiconductor, and the injection end point is reached. When this happens, a non-operation command is issued to this switch as well. Fuel supplied from a tank (not shown) is compressed to high pressure by a fuel pump 27, and then passed through a servo valve 28, which is a known electric/hydraulic conversion valve controlled by an appropriate method, to a predetermined amount by the method described later. The pressure is regulated, and by the control of the hydraulic solenoid valve SV that responds at high speed to the opening and closing operations of the high-speed switch SW, the fuel is sent under predetermined timing to the injection nozzle N of the engine EN, and the nozzle N injects fuel. A predetermined amount of fuel is injected into the diesel engine, and the diesel engine is operated according to the commanded rotation speed.

Note that the pressure control of the high-pressure fuel oil supplied to the injection valve N via the above-mentioned servo valve is normally performed as follows:
This is done by the following method. That is, when the engine speed is in the normal operating range, the normal range fuel injection pressure pattern generator shown in FIG. 29 operates, and the fuel injection pressure pattern generator shown in FIG. A built-in comparator (not shown) determines and outputs the fuel injection pressure corresponding to the engine speed from the tachometer TG. The valve command to the servo valve 28 is as described in . The comparator 32 is used to select one of the outputs of pattern generators 30 and 31 to maintain the engine speed near the minimum or maximum, which will be described later. The fuel injection pressure obtained through the servo valve is converted into an optimal servo valve command by appropriately combining adjustment elements such as proportional, integral, and differential, and its output is amplified through a commonly known amplifier 34. After that, it is applied to the servo valve 28.

Next, when the engine speed is out of the operating range of the normal range fuel injection pressure pattern generator 29 mentioned above and is about to drop below the minimum speed, or conversely when it is about to increase above the maximum speed. Regardless of the previous external fuel injection amount command, the minimum rotational speed securing pattern generator 31 and the maximum rotational speed securing pattern generator 30 operate to ensure the minimum rotational speed and maximum rotational speed, respectively, and the above-mentioned engine rotational speed is maintained. Generates a fuel injection pressure pattern according to the information.

In other words, if the previous fuel injection amount command is left unchanged due to an overload or the like, the engine speed will suddenly decelerate and the engine will come to a stop, the pattern shown at 51 and 51' in Fig. This increases the torque of the engine EN, prevents the rotation speed from decreasing below that level, and maintains the rotation speed at a substantially constant minimum rotation speed. Similarly, if the engine speed exceeds the maximum value due to sudden unloading for some reason and there is a risk of engine damage or abnormal combustion, the maximum rotation speed securing pattern generator 30 is activated.
The injection pressure reduction pattern shown in Figures 52 and 52' is generated, the injection pressure is reduced, the torque of the engine EN is suppressed, the rotation speed is prevented from increasing further, and the rotation speed is maintained near the maximum rotation speed. In addition, each output of these minimum and maximum rotation speed ensuring pattern generators 31 and 30 is outputted by a comparator 3.
2 and the output of the normal rotation speed pattern generator 29, and the most appropriate one corresponding to the engine rotation speed is selected.

In the above example, when the operating state of the engine changes, the start and end points of fuel injection change based on a predetermined pattern for the rotation speed from the perspective of the stroke, but the control of the fuel injection amount is not based on the timing. In particular, in the embodiment shown in Fig. 3, the length of the fuel injection timing (injection period) from the perspective of the stroke remains unchanged; This is a method of moving the timing in parallel while keeping the length constant according to changes in the rotational speed.

However, with such a method, even if such a fuel injection method is the best for the engine from a timing standpoint, the length of the fuel injection will be limited when the engine is running at low speed. It may become too long in terms of time, and in order to perform proper fuel injection, in other words, to prevent excessive fuel injection, the injection pressure may have to be abnormally reduced. As is well known, there is a limit to the fuel pressure that a diesel engine must inject into a cylinder for proper ignition, and it is not allowed to fall below that limit. If the engine speed is low during low fuel injection, a situation may occur where the required injection pressure value is too low.
Even if measures such as improving the injection nozzle are taken to solve this problem, it becomes a problem if the problem cannot be improved.

FIG. 4 depicts curves with the same purpose at the same coordinates as in FIG. 2, where 8' shows the pattern when a high injection command is given, and 9' shows the pattern when a low injection command is given. In FIG. 4, assuming that the minimum value of the fuel injection pressure mentioned above is set as shown in the figure, even if there is a difference in the magnitude of the output, if the engine speed falls below a certain value, Fuel cannot be injected at rotations lower than this value. Curve 1, which is further lower than curve 9'
If a low injection pressure such as 0' is required for engine control, fuel injection will not occur at all in any rotational speed range, and governor control itself will also not be possible at all. . Therefore, for the group of curves showing appropriate injection pressures according to each command injection amount in FIG. 4, the range indicated by the broken line that falls below the minimum fuel injection pressure value is the range that does not fall below the minimum fuel injection pressure value. to inject with,
That is, the injection pressure must be maintained at the minimum injection pressure, and control for ensuring a predetermined fuel injection amount must be performed by controlling the length of the injection period. In such a case, if it is preferable for the engine to delay only the injection start point as a method of reducing the injection timing, then equal amount of fuel injection should be maintained even in this rotation speed range. In order to achieve this, the timing of fuel injection may be performed in the manner shown in FIG. Figure 5, similar to Figure 1, shows the engine speed of the engine on the horizontal axis and the crank angle (stroke) on the vertical axis from near the fuel injection start point at maximum rotation to near the fuel injection end point at minimum rotation. 4' indicates the fuel injection start point, 5' indicates the fuel injection end point, 8'' indicates the pattern at the time of high injection command, 9'' indicates the pattern at the time of low injection command, and 12 indicates the pattern at the lowest rotation. 13 indicates the fuel injection start point at the lowest rotation, and 14 indicates the fuel injection start point at the highest rotation. If there is no minimum injection pressure limit for the engine's fuel injection timing, the fuel injection start point changes linearly between the engine's minimum and maximum engine speeds, as shown in Pattern 1 in Figure 2. However, in this embodiment, there is a limit to the injection pressure value, so when the engine speed drops below a certain number,
Since the injection pressure value does not fall below the minimum pressure value, an excess of the required fuel injection amount is supplied to the engine. To prevent this, the redundant fuel injection timing will be corrected. That is, for example, when injection pressure control is performed using the pattern at the time of a low injection command as shown in FIG. 4, when the engine speed R is ₁ or more, the fuel injection pressure is varied in equal injection periods using the patterns shown by 4' and 5'. Although fuel injection is performed, when the engine is operated at a lower engine speed, the period of fuel injection is reduced as shown in FIG. 5 in proportion to the decrease in engine speed. In other words, in the rotation speed range below R ₁ where equal pressure injection is forced,
A method of shortening the delay of the fuel injection start timing according to the pattern shown in 9'' as the engine speed decreases. In other words, the tip of the injection period is set to 0 when the engine speed is 0. The temporal length of the injection may be made constant by injecting in a pattern as shown in .With this method, the injection with equal pressure and equal time length is performed below the rotation speed. In the figure, when equal-pressure fuel injection is performed and the rotation speed is changed, even if it is affected by changes in the internal pressure of the cylinder, etc., the change in the fuel injection amount per unit time of the engine can be ignored.Of course, it is assumed that the change in the fuel injection amount per unit time of the engine can be ignored. Generally, this is sufficient, but if this cannot be ignored, it is necessary to conduct a test in advance, create a pattern based on the data obtained from this, and control using this pattern. When the engine output changes, for example, when the injection pressure is controlled according to the high injection command pattern shown in Fig. 4, as shown in the figure, the fuel decreases when the engine speed drops below _R2 . By delaying the injection start timing according to the pattern shown in 8'', the injection period is shortened and a predetermined amount of fuel is injected.

What I just described is a method that maintains the same amount of fuel injection when the injection pressure falls below the reference value in a specific rotation speed range, but conversely, it ensures equal amount of fuel injection as the rotation speed increases. Therefore, even if you want to increase the injection pressure, if the hydraulic equipment used cannot withstand the fuel injection pressure below a certain pressure, you have no choice but to keep the fuel injection pressure at the upper limit, and from then on In order to secure the required amount of fuel injection, it is necessary to perform control by varying (in fact, extending) the injection period, but the basic concept of such a control method is the same as the control method described in Figure 5. are the same.

The above has described the "method for controlling the fuel injection amount" itself, which injects a predetermined amount of fuel while maintaining the fuel injection pressure within the permissible limit. decreases,
Conversely, when there is a risk of overspeeding due to a light load, the engine speed can be maintained within a predetermined range using the same concept as the method just described. Specifically, when there is a risk that the engine speed will not be maintained at the minimum speed, the reduced fuel injection period is temporarily increased according to a predetermined pattern, and thus the fuel injection amount is increased. Furthermore, in order to prevent overspeeding, the idea is to conversely reduce the fuel consumption by shortening the injection period near the maximum rotation speed. When implementing this method, a greater effect can be obtained if the fuel injection pressure is also controlled, and this method can also be implemented. A detailed explanation will be given based on the fuel injection timing and period pattern diagram shown in the figure and the block diagram shown in FIG.

In FIG. 5, pattern 61 is an example of a curve showing the starting point of fuel injection to maintain the minimum rotation speed, and pattern 62 is an example of a curve showing the end point of fuel injection to prevent the maximum rotation speed from being exceeded. To explain pattern 61, if the engine is in an abnormal overload condition and the engine speed exceeds the allowable minimum speed and continues to decrease, the fuel injection start point is advanced based on the pattern shown in curve 61. , and the curve 5' indicating the fuel injection end point, that is, the fuel injection period is increased to increase the engine rotational torque and prevent the rotational speed from decreasing.

Therefore, if the engine is currently being operated according to the fuel injection command 8' in FIG. 4, if the rotational speed is _R2 or more, the pattern 4' in FIG.
5', the fuel injection start and end points are determined, and if the injection pressure is lower than R ₂ and maintained at the lowest pressure, the start point will be delayed according to pattern 8'' in Figure 5, and the injection time will be Equal pressure with constant target length,
Injections of equal time length are carried out. However, if the engine speed decreases beyond the minimum speed due to overload, etc., the start point of fuel injection is advanced based on the pattern of curve 61, and as mentioned earlier, the fuel injection period is extended, and the engine speed is further increased. Prevents rotation speed from decreasing. On the other hand, the same thing can be said about patterns 62 and 62', and when the engine speed accelerates due to sudden light load or no load, etc. and exceeds the maximum speed shown in Fig. 5, it indicates the end point of fuel injection. Instead of pattern 5',
The above-mentioned patterns 62, 62' are newly generated, the fuel injection end point is brought forward, the fuel injection period is significantly shortened, and a further increase in the engine speed is suppressed.

The details of securing the minimum and maximum rotational speeds in the equal-pressure, equal-time-length injection control described in FIGS. 4 and 5 will be explained with reference to the block diagram shown in FIG. 6.

In FIG. 6, components common to those shown in FIG. 3 are given the same reference numerals. That is, the EN is a two-stroke diesel engine equipped with a tachometer TG and a crank angle detector TD, and outputs information from these tachometer TG and angle detector TD to the injection timing detector 36 according to this embodiment. This detector 36 is the fifth
The same function pattern as shown in the figure is built-in, and by inputting the above two information and the fuel injection command from the outside, the start and end points of fuel injection are determined, and the high-speed switch SW operation and malfunction are determined. It issues an operation command and determines the fuel injection period, which is similar to the embodiment shown in FIG. 3 above. However,
The detector 36 in this embodiment of FIG.
As explained in the figure, if the engine speed reaches the minimum speed and there is a risk that it will continue to decrease, the above problem is solved by increasing the fuel injection period while maintaining the fuel injection pressure at a constant value. The pattern 61 is formed to rapidly advance the fuel injection start point near the lowest engine speed, and conversely, the engine speed increases by shortening the fuel injection period near the highest engine speed. A pattern 62 is formed to advance the fuel injection end point. Of course, the formation of these patterns 61 and 62 is performed based on the engine speed information from the tachometer TG reaching the minimum and maximum speeds, and the crank angle detector TD information. If minimum and maximum values are set for the fuel injection pressure mentioned above, in order to maintain injection at the minimum and maximum injection pressure values, it is necessary to reduce the injection period while reaching the minimum and maximum rotation speeds, or Pattern for extension, e.g. 8″,
As shown in the figure, the rotation speed R ₁ at the lowest pressure value or the rotation speed R ₂ at the highest pressure value is determined based on the value of the fuel injection command.
Based on these rotation speeds R ₁ and R ₂ , the engine rotation speed is
This is done in order to obtain equal injection time regardless of whether R is reduced to below ₁ or increased to above R ₂ . Note that the patterns 61 and 62 for maintaining the minimum and maximum rotational speeds are the patterns 8'' and 62 for forming equal injection periods at a constant injection pressure value, respectively.
Of course it also covers 11", pattern 8", 1
1'', but if the rotational speed deviates from the specified rotational speed, the injection period is lengthened or shortened by the patterns 61 and 62, and the rotational speed is maintained at a constant minimum or maximum rotational speed.

Further, 27 and 28 are a fuel pump and a servo valve, respectively, and the fuel compressed to high pressure is delivered to the injection nozzle N of the engine EN at a predetermined timing via a hydraulic solenoid valve SV that responds at high speed to the opening/closing operation of the high-speed switch SW. As a result, the nozzle N performs fuel injection and the diesel engine is operated at the commanded rotation speed. Furthermore, the fact that 33 and 34 represent a controller and an amplifier, respectively, is the same as in the block diagram of FIG. 3, and the roles they play are also the same. Note that the fuel injection pressure pattern generator 35 corresponds to the pattern generator 29 in FIG. This can be achieved by making them equal, that is, by respectively delaying the start point of fuel injection or, conversely, the end point of fuel injection along pattern 8'' or pattern 11''. In addition, for some reason, the organization
If EN deviates from the specified rotation speed, as described in the explanation of the fuel injection timing detector 36, follow the patterns 61 and 62 to determine the fuel injection start point or fuel injection end point. However, the fuel injection period becomes longer in the former case, while it becomes shorter in the latter case, and both maintain the engine speed near the minimum and maximum speeds in the normal range. Note that this means that the pattern in the pattern generator 35 is
For example, in cases such as 11' and 8', even if the minimum and maximum rotational speeds are reached before the fuel injection pressure reaches the allowable pressure value, the injection pressure remains unchanged. The pattern 11',
8', and if the injection timing is adjusted according to the patterns 61 and 62, the engine speed is maintained approximately at the specified minimum and maximum speeds. .

As mentioned above, the pattern generator 35 generates a pattern in response to two input information: the fuel injection amount command from the outside and the engine speed from the tachometer TG, and this pattern information is transmitted to the controller. After being sent to 35 and adjusted to an appropriate value, it is passed through an amplifier 34 and given to the servo valve 28 as a valve command. On the other hand,
Similar to the pattern generator, the fuel injection timing detector 36 receives an external fuel injection amount command, a tachometer TG,
Input three pieces of information from the crank angle detector TD, form a pattern as shown in the figure, select an appropriate pattern in cooperation with the injection pressure pattern generator 35, and issue operation commands to the next stage high-speed switch SW. , issuing a non-operation command is exactly the same as the detector 21 in the block diagram of FIG.

In addition, in order to obtain the speed regulating function of the maximum and minimum rotation speeds, the first embodiment is a method of rapidly decreasing or rapidly increasing the injection pressure, and the second embodiment is a method of shortening or extending the injection period.
Although each has been explained as an example, it is of course possible to obtain a greater effect by using both together, and the explanation as an example has been omitted.
As shown in FIG. 4 or as shown in pattern diagram 35 in FIG. 6, which corresponds to the second invention, the injection pressure pattern is limited to a minimum value or a maximum value in the normal range of engine speed. In such a case, a speed regulating function can be obtained by controlling the injection pressure to suddenly decrease or rapidly increase when the engine speed deviates to the maximum/minimum rotational speed range.

As described above, the present invention relates to a fuel injection control device for a diesel engine that controls the timing and period of fuel injection in a pattern according to engine speed information, and controls the amount of fuel injection based on injection pressure. This is to prevent the engine speed from exceeding the allowable speed and, if left as it is, continuing to drop and stopping the engine, or conversely continuing to rise and causing some damage. Therefore, based on the engine speed information, the allowable value In the case of the above and below rotation speeds, a pattern is generated to suddenly decrease or rapidly increase the injection pressure, and a pressure command is output based on the injection pressure sudden decrease or sudden pattern, and the engine rotation torque is adjusted to bring the rotation speed close to the maximum value. , to maintain the injection pressure near the minimum value, or to maintain the injection pressure at a constant value and control the fuel injection timing and period, in place of the sudden decrease or rapid increase control of the injection pressure, i.e., to start fuel injection near the minimum rotation speed. By accelerating the engine speed and lengthening the injection period, and conversely shortening the injection period by advancing the end of fuel injection near the maximum rotation speed, the engine speed can be brought closer to the allowable minimum and maximum rotation speeds. It is also possible to maintain the injection pressure or to use both of the above in combination, to control the injection pressure to suddenly increase or decrease rapidly, and to increase or decrease the fuel injection period near the minimum or maximum engine speed. Also, of course, in the above control, the allowable minimum and maximum values for the injection pressure are determined, and even if the engine speed is in the normal operating range, the injection pressure is forced to perform isobaric injection with the minimum or maximum value. The fuel supply during this period can also be applied to the injection period side, that is, when the engine speed is adjusted and the engine speed is controlled by performing injection over an equal period of time. Sudden pressure increase, sudden decrease control, or longer injection period in the latter case,
Both control methods, including shortening control and a method that simultaneously controls injection pressure and injection period, can fully prevent accidents such as engine stoppage and damage, regardless of the operating situation. This allows stable operation at all times.

[Brief explanation of drawings]

Figure 1 shows the fuel injection starting point relative to the engine speed.
The end point pattern, as shown in Figure 2, is a graph showing the pattern of fuel injection pressure versus engine speed;
The figure is a block diagram of a fuel injection control device incorporating a pattern generator that generates the patterns shown in Figures 1 and 2 above, and Figures 4 and 5 are fuel injection pressure pattern diagrams of other embodiments. , pattern diagram of fuel injection timing and period,
FIG. 6 is a block diagram of a fuel injection control device incorporating a pattern generator that generates the patterns shown in FIGS. 4 and 5. FIG. 21...Fuel injection timing detector, 27...Hydraulic pump, 28...Servo valve, 29...Normal range fuel injection pressure pattern generator, 30...Maximum rotation speed range injection pressure pattern generator, 31...Minimum Rotation speed range injection pressure pattern generator, 33...Controller, 35...Fuel injection pressure pattern generator, 36...Fuel injection timing detector, EN...Engine, TD...Crankshaft detector,
TG...Rotation speed detector, SW...High speed switch,
SV...Hydraulic solenoid valve, N...Injection valve.

Claims (1)

[Claims] 1. By using a valve that is operated by an electric command, the timing and period of fuel injection are controlled in a pattern according to engine speed information, and the amount of fuel injection is controlled by injection pressure, In the fuel injection control device of a diesel engine that controls the amount of fuel supplied, the pattern indicating the fuel injection pressure value determined according to the engine speed reaches its maximum value when the engine's allowable minimum speed is around or below. It has a pattern generator set to the lowest value in more than a few neighborhoods,
Only when the engine speed is outside the range around the allowable speed, the fuel injection pressure is controlled by the output information from the pattern generator, regardless of the external fuel injection command information, A diesel engine fuel injection control device characterized by the addition of a maximum and minimum rotation speed regulating function. 2. When controlling the timing and period of fuel injection in a pattern according to engine speed information by using a valve that is activated by an electric command, and controlling the amount of fuel injection by the pressure of fuel injection, When operating within a specific engine speed range determined by In the fuel injection control device, the pattern indicating the fuel injection pressure value determined according to the engine speed reaches the maximum value when the engine's allowable minimum speed is around or below.
In addition, if the engine has a pattern generator set to the lowest value when the engine speed is around the maximum allowable speed or higher, and the engine speed is outside the range around the allowable speed,
Fuel for a diesel engine, characterized in that the fuel injection pressure is controlled by the output information from the pattern generator regardless of the fuel injection command information received from the outside, and a maximum/minimum rotation speed regulating function is added. Injection control device. 3 By using a valve that is operated by an electric command, the timing and period of fuel injection is controlled in a pattern according to engine speed information, and when controlling the amount of fuel by the pressure of fuel injection, Diesel engine fuel that maintains the fuel injection pressure within an acceptable range by controlling only the fuel injection period and the amount of fuel supplied when operating within a specific engine speed range. In the injection control device, the pattern indicating the timing and duration of fuel injection determined according to the engine speed increases when the engine's allowable minimum speed is below or below, and when it is near the engine's maximum allowable speed or above. has a pattern generator that is set to shorten and shorten the engine speed, and only when the engine speed is outside the range around the allowable speed, the pattern is generated regardless of the fuel injection command information received from the outside. 1. A fuel injection control device for a diesel engine, which controls the timing and period of fuel injection based on output information from a diesel engine, and is further equipped with a maximum and minimum rotation speed regulating function.