JP4301982B2 - INTERNAL COMBUSTION ENGINE HAVING INJECTION PATTERN SWITCHING FUEL INJECTION DEVICE - Google Patents

Description

  The present invention relates to an internal combustion engine including an injection pattern switching type fuel injection device that can freely switch a combination of the number of injections and injection patterns of multi-stage injection and single-stage injection according to engine operating conditions and fuel injection states.

  As a means for improving engine performance and obtaining optimum exhaust gas performance, many multistage injections in which injection is performed a plurality of times in one cycle have been introduced. Such multi-stage injection is usually a small injection as a pilot injection before a main injection with a large injection amount, a small injection after a main injection, and a pre-injection and a post-injection of a main injection. However, there are three types of injection methods.

As an example of an internal combustion engine fuel injection device having an injection system that performs a small amount of injection for main injection before and after injection, there is a technique disclosed in JP-A-2002-213287.
In such a technique, a fuel injection device of a multi-stage injection system that performs a small amount of injection in main injection and pre-injection and post-injection of the main injection in one cycle of the engine, and control accuracy of the injection start timing of the fuel injection device The injection start time of the post injection can be calculated with high accuracy by using a two-dimensional map such as the main injection end delay time, the common rail pressure, the post injection start delay time, etc. It is configured to increase accuracy.

JP 2002-213287 A JP 2003-278549 A

  In a multi-stage fuel injection device that performs a small amount of injection in main injection and pre-injection and post-injection of the main injection, as disclosed in Patent Document 1, top dead center in one cycle of the engine In the vicinity of, the three stages of pre-injection, main injection, and post-injection are performed at regular time intervals, so that good exhaust gas performance can be obtained. At the time of injection, a situation occurs in which the fuel is not injected into the cavity of the piston but directly contacts the inner surface of the cylinder liner.

In such a situation, fuel adheres to the inner surface of the cylinder liner, the lubrication performance between the inner surface of the cylinder liner and the piston ring deteriorates, and seizure occurs between the piston ring and the inner surface of the cylinder liner. It tends to occur.
In order to avoid reaching such a situation, it is conceivable that the fuel injection direction is concentrated in the vicinity of the center of the cavity of the piston as disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 2003-278549). However, in this method, a lot of fuel adheres to the piston and the exhaust gas performance is suppressed, and there is a problem in terms of engine performance. This occurs when the engine is continuously operated with a single injection pattern determined during a certain steady operation.

  Therefore, in view of the problems of the prior art, the present invention is a fuel injection device for an engine that performs multi-stage injection including three stages of pre-injection, main injection, and post-injection. An internal combustion engine having a fuel injection device that prevents occurrence of seizure between the piston ring and the inner surface of the cylinder liner while maintaining performance and avoiding the occurrence of a situation in which the injected fuel directly contacts the inner surface of the cylinder liner The purpose is to provide.

To achieve the above object, the present invention provides an internal combustion engine (engine) having a fuel injection device that pressurizes fuel supplied from a fuel supply pump by a plunger and injects the fuel into a cylinder from a fuel injection valve. A multi-stage injection that performs a plurality of injections and a single-stage injection that performs a single injection in one cycle in which the spray from the fuel injection valve does not interfere with the cylinder liner are combined to constitute a plurality of cycles . Injection constituted by a plurality of cycles in which a multi-stage injection combining one repetitive injection pattern and a main injection performed at a predetermined injection interval from the previous injection is performed a plurality of times while changing the injection interval. to set corresponding multiple injection patterns to engine operating conditions of the engine speed and the engine load including a pattern, the A fuel injection pattern setting means, selecting a required injection pattern from the injection pattern setting means according to the engine operating condition detected from the engine, and controlling the fuel injection device to inject fuel according to the selected injection pattern A controller is provided.

According to this invention, there are multi-stage injection in which injection is performed a plurality of times in one cycle, and single-stage injection in which injection is performed once in one cycle in which the spray from the fuel injection valve is injected at a timing that does not interfere with the cylinder liner. Multi-stage injection combining one repetitive injection pattern composed of a plurality of cycles in combination and a pre-injection and a main injection performed at a predetermined injection interval from the pre-injection is performed a plurality of times at different injection intervals. A plurality of injection patterns including a plurality of cycles to be performed are set in the injection pattern setting means corresponding to the engine operating conditions of the engine speed and the engine load, and adapted to the engine operating conditions in the controller An injection pattern is selected and output to the fuel injection device, and the selected injection pattern is selected in the fuel injection device. It is possible to perform the fuel injection operation that. That is, even during operation in the steady state of the engine, the injection pattern is composed of one repeated injection pattern of a plurality of cycles, so it is not always constant for each cycle, and has a pattern in which a plurality of injection modes are combined. Driven.

Therefore, according to such an invention, among the many multi-stage injection patterns and the many injection patterns in which the multi-stage injection and the single-stage injection are combined, the multi-stage injection that can exhibit high engine performance and maintain good exhaust gas performance. The degree of freedom in selecting an injection pattern having three conditions so that the injected fuel does not directly contact the inner surface of the cylinder liner at the time of the multi-stage injection is increased, and the injection pattern of the multi-stage injection having both of the three conditions Or the injection pattern which combined this multistage injection and single stage injection can be easily set corresponding to an engine operating condition.
As a result, the engine can be operated with a fuel injection pattern that exhibits high engine performance, maintains good exhaust gas performance, and avoids direct contact of the injected fuel with the inner surface of the cylinder liner. It is possible to prevent the deterioration of the lubrication performance between the inner surface of the cylinder liner and the piston ring due to the direct contact with the inner surface of the liner, and the occurrence of seizure between the piston ring and the inner surface of the cylinder liner.

In this invention, the injection pattern is configured as follows.
(1) After performing the multistage injection once or a plurality of times, the single stage injection is performed once or a plurality of times.
In this way, even if the injected fuel contacts the inner surface of the cylinder liner during multistage injection including injection before the top dead center of the engine, the lubricating oil film is restored on the inner surface of the cylinder liner during the next single-stage injection. Thus, it is possible to prevent seizure from occurring between the piston ring and the inner surface of the cylinder liner while maintaining good lubrication performance.
(2) Multi-stage injection combining the pre-injection and the main injection performed at a predetermined injection interval from the pre-injection is performed a plurality of times while changing the injection interval.
In this way, by changing the injection interval between the pre-injection and the main injection in the multi-stage injection, the injection pattern changes with time, so the frequency of engine vibration and noise changes, and the noise feeling Improvement and noise reduction can be achieved. Further, it is possible to perform the fuel injection operation in which the optimal injection interval between the pre-injection and the main injection is selected to exhibit high engine performance and maintain good exhaust gas performance.
(3) After performing the multi-stage injection combining the pre-injection and the main injection once or a plurality of times, the multi-stage injection combining the main injection and the post-injection is performed once or a plurality of times.
In this way, the combustion performance can be improved by performing a small amount of post-injection and re-combustion during the post-burn period of main injection.

Further, the injection patterns (1), (2), and (3) can be combined as follows.
(4) After performing the multi-stage injection combining the pre-injection and the main injection performed at a predetermined injection interval from the pre-injection a plurality of times while changing the injection interval, the single-stage injection is performed once or a plurality of times.
(5) After performing the multi-stage injection combining the pre-injection and the main injection once or a plurality of times, performing the multi-stage injection combining the main injection and the post-injection once or a plurality of times, and then performing the single-stage injection once Or do it multiple times.
(6) Multi-stage injection combining the pre-injection and the main injection performed at a predetermined injection interval from the pre-injection is performed a plurality of times while changing the injection interval, and the main injection and the main injection are separated by a predetermined injection interval. The multi-stage injection combined with the post-injection performed at the same time is performed a plurality of times at different injection intervals.
(7) Multi-stage injection combining the pre-injection and the main injection performed at a predetermined injection interval from the pre-injection is performed a plurality of times while changing the injection interval, and the predetermined interval between the main injection and the main injection is increased. Multi-stage injection combined with post-injection performed in this manner is performed a plurality of times at different injection intervals, and single-stage injection is performed once or a plurality of times.

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  According to the present invention, among many multi-stage injection patterns and many injection patterns in which multi-stage injection and single-stage injection are combined, an injection pattern of multi-stage injection capable of exhibiting high engine performance and maintaining good exhaust gas performance. And the degree of freedom in selecting an injection pattern having three conditions so that the injected fuel does not directly contact the inner surface of the cylinder liner during the multi-stage injection increases, and the injection pattern of the multi-stage injection having the three conditions or An injection pattern in which the multi-stage injection and the single-stage injection are combined can be easily set corresponding to the engine operating conditions.

  As a result, the engine can be operated with a fuel injection pattern that exhibits high engine performance, maintains good exhaust gas performance, and avoids direct contact of the injected fuel with the inner surface of the cylinder liner. It is possible to prevent the deterioration of the lubricating performance between the inner surface of the cylinder liner and the piston ring due to the direct contact with the inner surface of the cylinder liner, and the occurrence of seizure between the piston ring and the inner surface of the cylinder liner.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  FIG. 1 is a configuration diagram including a partial cross section showing the overall configuration of an electromagnetic fuel injection device for a diesel engine according to an embodiment of the present invention. FIG. 2 is a control block diagram of an injection pattern in the embodiment. FIG. 3 is a timing diagram showing an embodiment of an injection pattern, and FIGS. 4A and 4B are cross-sectional views around the combustion chamber for explaining the operation.

In FIG. 1 showing the embodiment, reference numeral 100 denotes a fuel injection device, and in this embodiment, an electromagnetic unit injector is used. Such a unit injector 100 is well known. Briefly, the unit injector 100 includes a pump case 102, an injection nozzle 103 having an injection hole 104, a needle valve 105, a plunger 101, a tappet 110, It has a plunger spring 109, and further includes an electromagnetic valve device 120 having an armature 122 and a fixed iron core 121 for controlling the fuel injection timing and fuel injection amount, and an on-off valve device 123.
The plunger 101 is reciprocated up and down through a mechanism including a fuel cam 114, a cam follower 115, a push rod 113, a rocker arm 111, the plunger spring 109, a tappet 110, and the like. Reference numeral 108 denotes a high-pressure fuel passage that leads to the plunger chamber 106, and reference numeral 130 denotes a fuel inlet passage that leads to a fuel supply passage 128 described later. Reference numeral 131 denotes a leak passage through which fuel leaked from the gap between the plunger sliding portions is returned to the low-pressure fuel passage side.

  125 is a fuel tank in which fuel is stored, 128 is a fuel supply path connecting the fuel tank 125 and the fuel inlet passage 130 of the fuel injection device 100, 126 is a fuel supply pump, 127 is a filter, and 132 is the fuel injection. These are check valves that allow only the flow toward the device 100, and these constitute a fuel supply device to the fuel injection device 100.

1 is a controller that performs calculation and control, which will be described later, 3 is an engine speed detector that detects the engine speed, 4 is an engine load detector that detects the engine load, and 5 is a crank angle sensor that detects the crank angle of the engine. is there. Reference numeral 7 denotes an injection state detector for detecting the fuel injection timing and the fuel injection amount in the fuel injection device 100.
The detected value of the engine speed from the engine speed detector 3, the detected value of the engine load from the load detector 4, the detected value of the crank angle from the crank angle sensor 5, and the fuel injection from the injection state detector The detected values of timing and fuel injection amount are input to the controller 1.
6 is an injection pattern switching means for inputting an injection pattern switching signal in the fuel injection device 100 to the controller 1 described later.

Next, the operation of this embodiment will be described with reference to FIG.
The detected value of the engine speed from the engine speed detector 3, the detected value of the engine load from the load detector 4, the detected value of the crank angle from the crank angle sensor 5, and the fuel injection from the injection state detector The detected values of the timing and the fuel injection amount are input to the injection pattern selection unit 12 of the controller 1.
Reference numeral 11 denotes an injection pattern setting unit. In the injection pattern setting section, a multi-stage injection pattern in which injection is performed a plurality of times per cycle and a single-stage injection pattern in which injection is performed once per cycle correspond to the engine operating conditions such as the engine speed and the engine load. And it is set as follows.

That is, as shown in FIG. 3 (A), the first injection pattern is a multi-stage injection in which a pre-injection A having a smaller injection amount than the main injection B and a main injection B having a large injection amount are performed twice per cycle ( This is an injection pattern in which the single-stage injection C is performed twice (may be once or three times or more) after being performed once or three times or more.
In such a first injection pattern, during multistage injection A and B including injection before the top dead center of the engine, even if the injected fuel contacts the inner surface of the cylinder liner, The lubricating oil film is restored on the inner surface of the liner, and good lubrication performance is maintained, and the occurrence of seizure between the piston ring and the inner surface of the cylinder liner can be prevented.

As shown in FIG. 3 (B), the second injection pattern is a multi-stage injection in which the pre-injection A and the main injection B performed at a predetermined injection interval t from the pre-injection A are combined with the pre-injection A. The injection interval t with the main injection B is periodically changed such that the first time is t ₁ , the second time is t ₂ , the third time is t ₁ , and the fourth time is t ₂ .
In the second injection pattern, since the injection pattern changes with time by changing the injection interval t between the pre-injection A and the main injection B in the multistage injection, the frequency of engine vibration and noise changes. The noise feeling can be improved and the noise can be reduced. Further, it is possible to perform the fuel injection operation by selecting the injection interval t ₁ or t ₂ between the pre-injection A and the main injection B that is optimal for exhibiting high engine performance and maintaining good exhaust gas performance.

As shown in FIG. 3C, the third injection pattern alternately performs multi-stage injection combining the front injection A and the main injection B and multi-stage injection combining the main injection B and the post-injection D. Multi-stage injection combining the front injection A and the main injection B may be performed twice or more, and multi-stage injection combining the main injection B and the post-injection D may be performed twice or more.
In the third injection pattern, the combustion performance can be improved by performing a small amount of post-injection D during the post-burn period of main injection B and performing re-combustion.

Moreover, in the said injection pattern setting part 11, the injection pattern which combined the said 1st, 2nd, 3rd injection pattern as shown to following (1)-(4) is also set.
(1) After performing the multi-stage injection combining the pre-injection A and the main injection B performed at a predetermined injection interval t from the pre-injection A a plurality of times with the injection interval t changed, the single-stage injection C is performed. Perform once or multiple times.
(2) After performing the multi-stage injection combining the pre-injection A and the main injection B once or a plurality of times, the multi-stage injection combining the main injection B and the post-injection D is performed once or a plurality of times, and then a single stage The injection C is performed once or a plurality of times.

(3) The multi-stage injection combining the pre-injection A and the main injection B performed at a predetermined injection interval t from the pre-injection A is performed a plurality of times while changing the injection interval t, and the main injection B and the main injection Multi-stage injection combined with post-injection D performed at a predetermined injection interval t from B is performed a plurality of times while changing the injection interval t.
(4) The multi-stage injection combining the pre-injection A and the main injection B performed at a predetermined injection interval t from the pre-injection A is performed a plurality of times while changing the injection interval t, and the main injection B and the main injection Multi-stage injection combined with post-injection D performed at a predetermined injection interval t from B is performed a plurality of times while changing the injection interval t, and single-stage injection C is performed once or a plurality of times.

  Next, when an injection pattern switching signal in the fuel injection device 100 is input from the injection pattern switching means, the injection pattern selection unit 12 performs injection based on the detected value of the engine speed and the detected value of the engine load. The pattern setting unit 11 selects the multi-stage injections A, B, D and single-stage injection C set as described above and inputs them to the electromagnetic valve opening / closing control unit 13.

Further, in the injection pattern selection unit 12, based on the detected values of the fuel injection timing and the fuel injection amount input from the injection state detector 7, the multi-stage injections A, B, D and the single-stage injection C are The selected injection pattern based on the detected value of the engine speed and the detected value of the engine load is complemented.
Thus, by adding feedback control based on the detected values of the fuel injection state such as the fuel injection timing and the fuel injection amount, the fuel injection pattern can be made to exactly match the target injection pattern.

Further, the operation time of the multi-stage injection is detected and input to the injection pattern selection unit 12, and the injection pattern selection unit 12 sets the relationship between the operation time of the multi-stage injections A, B, and D and the engine speed. The multistage injection operation time corresponding to the engine speed detection value is selected from the value, and the selected injection pattern is complemented.
In this way, the multistage injection operation time corresponding to the engine rotational speed detection value is selected from various injection patterns of the multistage injections A, B, and D, and the feedback control that injects the fuel by the selected injection pattern enables high engine performance. As well as maintaining good exhaust gas performance, it is possible to set the operation time of multistage injection that can avoid the direct contact of the injected fuel with the inner surface of the cylinder liner.

  In the electromagnetic valve opening / closing control unit 13, an operation signal that results in the injection pattern selected by the injection pattern selection unit 12 is input to the electromagnetic valve driving circuit 2, and the electromagnetic valve driving circuit 2 switches the electromagnetic valve 120, The fuel injection device 100 opens and closes with the target injection pattern, whereby the fuel injection device 100 performs fuel injection with the selected injection pattern.

  According to this embodiment, the controller 1 combines the main injection B and the pre-injection A or the post-injection B having a smaller injection amount than the main injection B in accordance with the engine operating conditions such as the engine speed and the engine load. Multi-stage injection and single-stage injection C that performs injection once in one cycle are set by changing the injection patterns in the multi-stage injections A, B, and D, or the multi-stage injections A, B, and D When the combination mode with the injection C is set in various ways and an injection pattern switching command signal is input to the injection pattern selection unit 12 of the controller 1 by the injection pattern switching means 6, the injection pattern selection unit 12 receives the engine. An injection pattern adapted to the operating conditions is selected and output to the fuel injection device 100, and the selected injection pattern is selected in the fuel injection device 100. It can perform fuel injection operation by the made.

  Here, as shown in FIG. 4A, in one cycle of the engine, the fuel spray 134 by the multi-stage injection of the pre-injection A, the main injection B, and the post-injection D in the vicinity of the top dead center at a constant time interval. On the other hand, as shown in FIG. 4 (B), when the pre-injection A or the post-injection D, which is an injection at a time away from the top dead center, is obtained, the fuel spray 134 is applied to the piston 130. This causes a situation where the cylinder liner 131 directly contacts the inner surface of the cylinder liner 131 without being injected into the combustion chamber 133. The other members in FIG. 4A are the same as in the embodiment of FIG.

However, according to the embodiment, among the many multistage injection patterns and the many injection patterns in which the multistage injections A, B, D and the single stage injection C are combined, high engine performance and good exhaust gas performance are achieved. The injection pattern of the multistage injections A, B, and D that can be maintained, and the injection pattern that has three conditions so that the fuel spray 134 does not directly contact the inner surface of the cylinder liner 131 during the multistage injections A, B, and D as described above. The degree of freedom to select the engine is increased, and the injection pattern of the multi-stage injections A, B, D having the above three conditions or the injection pattern combining the multi-stage injections A, B, D and the single-stage injection C is used. It can be easily set according to the operating conditions.
As a result, the engine can be operated with a fuel injection pattern that exhibits high engine performance, maintains good exhaust gas performance, and avoids direct contact of the injected fuel with the inner surface of the cylinder liner. It is possible to prevent the deterioration of the lubrication performance between the inner surface of the cylinder liner and the piston ring due to the direct contact with the inner surface of the liner, and the occurrence of seizure between the piston ring and the inner surface of the cylinder liner.

  According to the present invention, in a fuel injection device for an engine that performs multi-stage injection including three-stage injection including pre-injection, main injection, and post-injection, the injection is performed while maintaining good exhaust gas performance and high engine performance in the entire operation range. It is possible to provide a fuel injection device that prevents occurrence of a situation in which fuel directly contacts the inner surface of the cylinder liner and prevents seizure between the piston ring and the inner surface of the cylinder liner.

1 is a configuration diagram including a partial cross section showing the overall configuration of an electromagnetic fuel injection device for a diesel engine according to an embodiment of the present invention. It is a principal part systematic diagram which shows the other Example of the path | route which adds the lubricity improver in the said 1st Example to a low-viscosity fuel. It is a control block diagram of the injection pattern in an Example. (A), (B) is sectional drawing of the combustion chamber periphery for demonstrating an effect | action.

100 Fuel injector (Electromagnetic unit injector)
DESCRIPTION OF SYMBOLS 101 Plunger 120 Electromagnetic valve apparatus 123 On-off valve apparatus 126 Fuel supply pump 128 Fuel inlet path 38 Variable throttle valve 1 Controller 2 Electromagnetic valve drive circuit 3 Engine speed detector 4 Load detector 5 Crank angle sensor 6 Injection pattern switching means 7 Injection Condition detector

Claims (2)

In an internal combustion engine (engine) including a fuel injection device that pressurizes fuel supplied by a fuel supply pump by a plunger and injects the fuel into a cylinder from a fuel injection valve.
A multistage injection for performing multiple injections in one cycle, by spraying are combined and a single-stage injection for performing one injection per cycle is injected at a timing that does not interfere with the cylinder liner plurality of cycles of the fuel injection valve Consists of a plurality of cycles in which a multi-stage injection combining a single repeated injection pattern configured and a main injection performed at a predetermined injection interval from the previous injection is performed a plurality of times at different injection intervals. the injection pattern includes a spray pattern setting means for setting in response to a plurality of injection patterns to engine operating conditions of the engine speed and engine load, by the engine operating condition detected from the engine comprising, an injection pattern A required injection pattern is selected from the setting means, and fuel is injected by the selected injection pattern. Engine with an injection pattern switching type fuel injection apparatus characterized by comprising a controller for controlling the fuel injection device. The injection pattern setting means further performs one or a plurality of times of multi-stage injection combining the pre-injection and the main injection, and then performs one or more times of multi-stage injection combining the main injection and the post-injection. 2. An internal combustion engine having an injection pattern switching type fuel injection device according to claim 1, wherein an injection pattern constituted by a plurality of cycles is set.

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