JPH04301140A - Controller for engine - Google Patents

Abstract

PURPOSE:To solve the trouble that the combustion stability is deteriorated with trouble, by compulsorily switching to the first intake state, by freely selecting the intake state where intake is completed at a prescribed crank angle and the intake state where intake is delay-closed. CONSTITUTION:A two-cylinder type rotary piston engine E is equipped with a communication port which is closed in delay in comparison with an intake port for each cylinder, in order to reduce pumping loss. The first intake state where intake is completed at a prescribed crank angle and the second intake state where intake is completed at the delayed crank angle in comparison with the first intake state can be selected by an intake state selecting means A. The selecting means A is controlled by a selection control means B on the basis of the prescribed condition. In this case, a trouble detecting means C for detecting the trouble in the intake state selection control is installed. When trouble is detected, the selection to the first intake state is compulsorily carried out by a trouble control means D.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine control device.

0002

2. Description of the Related Art As fuel supply modes for supplying fuel to an engine, two methods are considered: one is to supply fuel to an intake passage using a fuel injection valve, and the other is to supply fuel directly into a cylinder. While supplying fuel to the intake passage is preferable in terms of promoting fuel vaporization and atomization, it is not fully satisfactory in terms of responsiveness and combustion stability under light loads. Further, when fuel is directly supplied into the cylinder, although it is preferable in terms of combustion stability and responsiveness due to stratification of the fuel, it is not fully satisfactory in terms of vaporization and atomization of the fuel.

[0003] From the above-mentioned viewpoint, Japanese Patent Application Laid-Open No. 1-318
No. 725 proposes switching between a mode of supplying fuel to an intake passage and a mode of supplying fuel directly into a cylinder, depending on the operating state of the engine. This publication also states that in order to reduce pumping loss in a two-cylinder rotary piston engine, a communication port that closes later than the intake port is provided for each cylinder, and the communication port is closed later than the intake port. There has also been disclosed a device in which the two ports are communicated with each other through a communication path, and a control valve consisting of an on-off valve that substantially switches the intake end timing is disposed in the communication path.

0004

[Problems to be Solved by the Invention] As mentioned above, in an engine that performs late intake closing, the operating range in which this late intake closing is performed is determined by the parameters of engine speed and engine load, for example. Normally, this is carried out only in a predetermined operating range set as a controller. In other words,
Switching control as to whether or not to execute late intake closing is performed based on predetermined conditions.

However, for some reason, it is conceivable that a failure may occur in which switching control as to whether or not to perform intake late closing is not performed normally. If such a failure occurs, the intake air will be closed late in an operating range in which it would normally not be closed, resulting in a problem that combustion stability will be extremely deteriorated.

[0006] Therefore, an object of the present invention is to perform switching control on whether or not to perform intake late closing based on predetermined conditions, and to appropriately respond to the occurrence of a failure in which this switching control is no longer performed normally. An object of the present invention is to provide an engine control device that allows the engine to control the engine.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention has the following first structure. That is, as shown in the block diagram in FIG. 6, there are a first intake state in which intake ends at a predetermined crank angle, and a second intake state in which intake ends at a crank angle later than in the first intake state. an intake state switching means for switching the intake state switching means; a switching control means for controlling the switching of the intake state switching means based on a predetermined condition set in advance; and a failure in which the switching control for the intake state switching means is not performed normally. failure detection means for detecting that the first intake state The configuration includes a failure control means for setting the state.

The second configuration of the present invention is as follows. That is, as shown in a block diagram in FIG. 7, there are a first intake state in which intake ends at a predetermined crank angle, and a second intake state in which intake ends at a crank angle later than in the first intake state. an intake state switching means for switching the intake state switching means; a switching control means for controlling switching of the intake state switching means based on a predetermined condition set in advance; and a switching control means for switching the intake state switching means while the intake state switching means remains in the second intake state. a failure detection means for detecting that a failure has occurred, and a failure control means for changing a control value of the engine in a direction that stabilizes combustion when the failure occurrence is detected by the failure detection means. It is configured as follows.

[0009]

[Effects of the Invention] By adopting the above-mentioned first configuration, when a failure occurs, the intake state in which the intake air is closed late is prohibited, and it is possible to prevent extreme deterioration of combustion in the operating region where the intake air late closing is not performed. . In other words, when the intake air is closed late, combustion tends to be worse than when the intake air is not closed late, and the switching conditions are set with a balance between such combustibility and the effect of reducing pumping loss. It is normal to Therefore, executing late intake closing in a region where intake late closing is not originally intended would result in extremely poor combustion, but according to the present invention, such a problem can be solved.

It is conceivable that a failure may occur in which the intake state switching means becomes stuck in the second intake state in which the intake air is closed late, making it impossible to switch to the first intake state. In this case, extreme combustion deterioration would be unavoidable in the operating range where intake late closing would not normally be performed, but by adopting the second configuration, the engine control value can be adjusted in the direction of combustion stabilization. Even in this case, extreme combustion deterioration can be prevented. Examples of setting engine control values in the direction of combustion stabilization include an increase in cooling water temperature, enrichment of the air-fuel ratio, and increase in idle speed.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, the engine E has a first cylinder R
It is a Wankel type two-cylinder rotary piston engine having an E1 and a second cylinder RE2. Each cylinder RE1
and RE2 have similar configurations, so the first cylinder R
The structure will be explained focusing on E1, and the second cylinder RE2 will be given the same reference numerals as those used in the explanation of the first cylinder, thereby omitting redundant explanation.

First, the cylinder RE1 is connected to the rotor housing 1.
It has a rotor 2 housed within the cylinder, and three working chambers 3, 4, and 5 are defined within the cylinder by the rotor 2. Each of the working chambers 3, 4, and 5 periodically repeats suction, compression, expansion (explosion), and exhaust strokes in accordance with the planetary motion of the rotor. In the state of FIG. 1, for the first cylinder RE1, the working chamber 3 is in the intake stroke, the working chamber 4 is at the compression top dead center, and the working chamber 5 is in the exhaust stroke, and the second cylinder RE1 is in the exhaust stroke.
2 shows the case where the working chamber 3 is in the compression stroke, the working chamber 4 is in the expansion stroke, and the working chamber 5 is in the final stage of the exhaust stroke.

Three spark plugs 6, 7 and 8, first to third, are provided for one cylinder. The first spark plug 6 is located on the slightly advanced side of the trochoid short axis (rotor 2
The second spark plug 8 is located on the leading side of the rotational direction (the same applies hereinafter), the second spark plug is located slightly on the lag side with respect to the trochoid short axis, and the third spark plug 8 is located on the most lag side end of the working chamber at compression top dead center. Located nearby. Then, when the engine speed is high (a predetermined speed or higher), the ignition of the third spark plug 8 is stopped, and the ignition of the first and second spark plugs 6 is stopped.
, 7 only, and in other operating conditions, all spark plugs 6, 7, and 8 ignite. The ignition timing is sequentially advanced from the ignition plug located on the lag side in the rotational direction of the rotor to the ignition plug located on the advance side.

An intake port 11 and a communication port 12 that closes later than the intake port 11 are formed in the side housing 9 of each cylinder R1 and RE2. The timing of the communication port 12 is set so that when one cylinder is in the compression stroke, the other cylinder is in the intake stroke. More specifically, the opening timing of the communication port 14 is, for example, in the range of 85 degrees to 110 degrees after the intake top dead center (85 degrees in the embodiment), and the closing timing of the communication port 14 is, for example, 110 after intake top dead center
It can be set in the range of 130 degrees to 130 degrees (130 degrees in the embodiment). These communication ports 12 communicate with each other through a communication passage 13 (the communication passage 13 is actually formed in the intermediate housing), and this communication passage 13 is opened and closed by a control valve 14.

Reference numeral 21 in FIG. 1 is an intake passage extending from the air cleaner 20, and its downstream end is branched into two, with one branched intake passage 21A connecting to the intake port 11 of the first cylinder RE1. The other branch intake passage 21B is connected to the intake port 11 of the second cylinder RE2. Two exhaust turbo superchargers 22 and 23 are connected to this intake passage 21. The supercharger 22 is a primary supercharger that always performs supercharging, and the supercharger 23 is a secondary supercharger that performs supercharging only in a predetermined operating state.

The compressor 22a of the primary supercharger 22 is
It is connected to the intake passage 21 so that intake air always passes through the compressor 22a. The intake passage 21 also has a bypass passage 21C that bypasses the compressor 22a of the primary supercharger 22, and the bypass passage 21C has a bypass passage 21C that bypasses the compressor 23a of the secondary supercharger 23.
is connected. And in the bypass passage 21C,
An on-off valve 24 is provided downstream of the compressor 23a. In addition, upstream of the on-off valve 24 and the secondary supercharger 23
The intake recirculation passage 2 communicates with the upstream side of the compressor 23a.
1D, and an on-off valve 25 is provided in this recirculation passage 21D.

The turbine 22b of the primary supercharger 22 is connected to the exhaust passage 32 extending from the exhaust port 31 of each cylinder RE1, RE2, and the exhaust gas is constantly supplied to the turbine 22.
It is set to pass b. The exhaust passage 32 is
Wastegate passage 32 bypassing turbine 22b
A, and a wastegate valve 33 is disposed in this wastegate passage 32A.

[0018] The exhaust passage 32 further includes a primary supercharger 22.
The engine has a bypass passage 32B that bypasses the turbine 22b and the wastegate passage 32A, and a turbine 23b of the secondary supercharger 23 is connected to the bypass passage 32B. This bypass passage 32B is branched into two passages with different sizes of opening area near the inlet of the turbine 23b, and one branch passage having a small opening area is provided with an on-off valve 34, and has a large opening area. An on-off valve 35 is provided in the branch passage.

The operation of the superchargers 22 and 23 is as follows. Now, when all the valves 24, 33, 34, and 35 are closed, supercharging is performed only by the primary supercharger 22 (the secondary supercharger 23 is stopped). When the supercharging pressure increases, the on-off valve 34 is eventually opened and the secondary supercharger 23 is pre-rotated. If the boost pressure is further increased after this pre-rotation, 2
The rotation of the secondary supercharger 23 is greatly increased, and the discharge pressure from the secondary supercharger 23 is increased. When the discharge pressure from the secondary supercharger 23 becomes the same as the supercharging pressure downstream of the primary supercharger 22, the on-off valve 24 is opened, and thereby supercharging by both superchargers 22 and 23 is started. It is done. When the supercharging pressure exceeds a predetermined value, the waste gate valve 33 is opened to prevent the supercharging pressure from increasing above the predetermined pressure. Also, during pre-rotation of the secondary supercharger 23, an on-off valve 2 provided in the recirculation passage 21D is installed to prevent surging of the compressor 23a.
5 is open, and the on-off valve 25 is closed while both superchargers 22 and 23 are supercharging. Incidentally, since the operation of such a so-called sequential turbo is known, further detailed explanation will be omitted.

Exhaust passage 3 downstream of turbines 22a, 22b
2 is connected to a three-way catalyst 36, and a muffler 37 is connected downstream of the catalyst 36. This muffler 37 has two exhaust pipes 37A and 37B, one of which is
An on-off valve 38 is connected to 7A. This on-off valve 38 is closed during low rotation or low load, and is open during other operating conditions.

An air pump 41 is provided for the exhaust system. This air pump 1 is driven by the engine E via an electromagnetic clutch (not shown), and is connected to an air passage 42 led out from the intake passage 21 downstream of the compressors 22a and 23a of the superchargers 22 and 23. . A switching valve 43 is connected to the air passage 42.
3, the branch air passage 42A is connected to the middle part of the catalyst 36 (for split air supply), and the branch air passage 42B is connected to the exhaust air of each cylinder RE1, R2. It is opened to port 31 (for port air supply). The switching valve 43 supplies secondary air to the exhaust port 31 at low rotation speeds and in a rotation range where fuel feedback control is performed, which will be described later, and in a lower load range than this feedback range. . In addition, the switching valve 43 is configured to control the catalyst 3 in the feedback region.
6 is supplied with secondary air. In other operating states than those mentioned above, the operation of the air pump 41 is stopped or
The secondary air is relieved by a relief passage (not shown), and no secondary air is supplied.

A first fuel injection valve 51 serving as a first fuel supply means for injecting fuel into the branch intake passages 21A, 21B is disposed for the branch intake passages 21A, 21B. Further, each cylinder RE1, RE2 is provided with a second fuel injection valve 52 serving as a second fuel supply means for injecting fuel directly into the cylinder. This second fuel injection valve 5
A fuel passage 53 is formed in the side housing 9 for supplying fuel from the fuel tank 2 . The downstream end of this fuel passage 53 is opened into the cylinder at a timing position such that it is opened during the compression stroke and slightly before the communication port 12 is closed. And fuel passage 5
3, the fuel from here flows into the first and second spark plugs 6,
The position is set so that it flows toward around 7. The second fuel injection valve 52 is attached to the side housing 9 so as to inject fuel into the fuel passage 53.

An air pump 61 is provided for the intake system. This air pump 61 is driven by the engine E via an electromagnetic clutch (not shown), and is connected to an air passage 62 led out from the intake passage 21. It is connected. The air passage 62 is branched into two, one branch air passage 62A is supplied to the second fuel injection valve 52 of the first cylinder RE1, and the other branch air passage 62B is supplied to the second cylinder RE2.
The second fuel injector 52 is supplied with the second fuel injector 52 . The air supplied to the second fuel injection valve 52 is used to promote vaporization and atomization of the fuel injected from the second fuel injection valve 52, and
It functions to clean the fuel passage 53. Note that the air pump 61 is operated only in a region where fuel is injected from the second fuel injection valve 52.

From the intake passage 21, there is further an air passage 63.
has been derived. This air passage 63 is branched into two, one branch air passage 63A is connected to the first fuel injection valve 51 in the first cylinder RE1, and the other branch air passage 63A is connected to the first fuel injection valve 51 in the first cylinder RE1.
3B is connected to the first fuel injection valve 51 in the second cylinder RE2. Of course, the air from this air passage 63 is
This serves to promote vaporization and atomization of the fuel injected from the first fuel injection valve 51.

The intake passage 21 includes a branch intake passage 21A,
A sensor 71 that detects intake pressure as an engine load is connected at a position immediately upstream of 21B, and a throttle valve 72 is disposed immediately upstream of the sensor 71. Further, the exhaust passage 32 includes a turbine 22b.
, 23b, an air-fuel ratio sensor 73 and an exhaust temperature sensor 74 for detecting exhaust gas temperature are connected.

Next, the basic manner of supplying fuel and the basic manner of operation of the control valve 14 for reducing pumping loss will be explained based on FIG. 2. This Fig. 2 is a map set with engine load and engine speed as parameters. In the figure, R1 to R3 indicate the boundaries of engine rotation, B1 to B8 indicate the boundaries of engine load, and indicates the no-load line. First, regarding the air-fuel ratio relationship of fuel, an increase correction as shown in FIG. 2 is performed. Also,
Feedback correction (F/B correction) of the air-fuel ratio using the output of the air-fuel ratio sensor 73 is performed in a predetermined region.

Regarding fuel cut, when the load is relatively high, only one cylinder is cut, and when the load is low, all cylinders are cut. Fuel restoration is performed in the same way; in the region shown as one-sided fuel cut in Figure 2, fuel is restored only to some cylinders; When the range is reached, fuel is returned to all cylinders.

Next, the control valve 14 is basically opened in the region hatched with broken lines in FIG. The control valve 14 is opened in the rotation range between the rotation lines R1 and R3 and below the engine load line B8, except for the entire fuel cut area. In the rotation range between rotation lines R1 and R3,
The control valve 14 opens in the one-sided fuel cut region when the control valve 1
This is to reduce the frequency of opening and closing of No. 4 and to prevent torque shock when switching between deceleration and end of deceleration. rotation line R
The reason why the control valve 14 is closed in the entire fuel cut region in the rotation range between 1 and R3 is to increase the effective compression ratio and obtain sufficient engine braking. In the idle area,
Although the control valve 14 is closed, it may be opened. The control valve 14 is closed in areas other than the open area of the control valve 14 described above.

FIG. 3 shows which fuel injection valves 51 and 52 are used for fuel injection. 3 corresponds to FIG. 2, and in the hatched area in FIG. 3, fuel is injected only from the two fuel injection valves 52. As understood from the hatching in FIG. 3, in the rotation range between the rotation speed lines R1 and R3 and the engine load line B
In the low load region below 8, fuel is injected only from the second fuel injection valve 52, except in the entire fuel cut region.

Furthermore, regardless of the engine speed, fuel is injected only from the second fuel injection valve 52 in all one-sided fuel cut regions. This is to concentrate the supplied fuel only on one cylinder and stratify the fuel with the fuel injected from the second fuel injection valve 52, thereby sufficiently improving combustion stability. Of course, the fuel injection timing of the second fuel injection valve 52 is set after the communication port 12 is closed.

Further, during idling, fuel is injected only from the first fuel injection valve 51, but the second fuel injection valve 5
Fuel injection may be performed only from 2. In all operating ranges other than those described above, fuel is injected from both the first and second fuel injection valves 51 and 52 (ensuring a sufficient amount of fuel injection) except for the entire fuel cut range.

FIG. 4 shows a control system, and U in the figure is a control unit constructed using a microcomputer. This FIG. 4 shows the input/output relationship to each of the above-mentioned components, and in this FIG. A sensor 80 for detecting the number is a switch that is turned on only when the control valve 14 is opened (or closed) to detect the open/closed state of the control valve 14. Further, reference numeral 81 denotes an alarm consisting of a lamp, a buzzer, etc., which is activated when a failure occurs to notify the driver that a failure has occurred.

Of the control contents of the control unit U shown in FIG. 4, FIG. 5 shows a focus on control related to the occurrence of a failure.
It is. The flowchart shown in FIG. 5 will be explained below, and in the following explanation, S indicates a step. First, in S1, signals from each sensor are inputted, and then in S2, it is determined whether or not the switching control of the control valve 14 is not performed normally.

[0034] Examples of the types of fail determined in S2 are as follows. That is, if each sensor used for switching control of the control valve 14, especially the sensors 79 and 75 that detect engine speed and engine load, fails (output voltage abnormality), or if the control unit U is abnormal (CPU self-control), diagnosis or mutual monitoring between multiple CPUs), there may be a mismatch between the opening/closing signal of the control valve 14 from the control unit U and the operating state of the switch 80. In particular, it can be easily determined by using the switch 80 whether or not the control valve 14 has failed, such as being stuck open.

If the determination in S2 is NO, it is normal, so in S3 the control valve 14 is set to open or close according to the map shown in FIG.

When the determination in S2 is YES, the alarm 81 is activated in S4, and then in S5 it is determined whether the type of failure is that the control valve 14 is stuck open. . If the determination in S5 is YES,
In S7, the engine control value is changed in the direction of combustion stabilization, and subsequently in S8, the supply of secondary air to the exhaust system is prohibited.

To change the engine control value in the direction of combustion stabilization, for example, enrich the air-fuel ratio, increase the cooling water temperature (
(Ignition timing retardation and thermostat setting temperature change)
, all the first to third spark plugs 6 to 8 may perform ignition. Further, the reason why the secondary air supply is prohibited in S9 is to protect the catalyst. Note that the change in the engine control value may be limited to only the operating range in which the control valve 14 is normally closed in reference to the map shown in FIG.

If the determination in S5 is NO, the control valve 14 is forcibly closed in S6.

Although the embodiments have been described above, the present invention can be similarly applied to reciprocating engines.

[Brief explanation of drawings]

FIG. 1 is an overall system diagram showing one embodiment of the present invention.

FIG. 2 is a map showing opening/closing regions of a control valve 14 for reducing pumping loss.

FIG. 3 is a map showing a setting range for determining which fuel injection valve is used to inject fuel out of a first fuel injection valve and a second fuel injection valve.

FIG. 4 is a control system diagram showing the input/output relationship to the control unit.

FIG. 5 is a flowchart showing a control example of the present invention.

FIG. 6 is a block diagram showing a first configuration of the present invention.

FIG. 7 is a block diagram showing a second configuration of the present invention.

[Explanation of symbols]

U Control unit E engine RE1 1st cylinder RE2 2nd cylinder 11 Intake port 12 Communication port 13. Communication path 14 Control valve 21 Intake passage 21A Branch intake passage 21B Branch intake passage 51 First fuel injection valve 52 Second fuel injection valve 53 Fuel passage 75 Engine load sensor 70 Engine speed sensor 80 Control valve 14 position detection switch 81 Alarm

Claims (3)

[Claims] Claim 1: A first engine that terminates intake at a predetermined crank angle.
an intake state switching means for switching between an intake state and a second intake state in which intake ends at a crank angle later than that in the first intake state; a switching control means for controlling the switching of the intake state switching means; a failure detection means for detecting a failure in which the switching control for the intake state switching means is no longer performed normally; and a failure detection means when the occurrence of a failure is detected by the failure detection means. . A control device for an engine, comprising: failure control means for controlling the intake state switching means with priority over the switching control means to forcefully set the intake state to the first intake state. [Claim 2] A first engine that terminates intake at a predetermined crank angle.
an intake state switching means for switching between an intake state and a second intake state in which intake ends at a crank angle later than that in the first intake state; a switching control means for controlling the switching of the means; a failure detection means for detecting a failure in which the intake state switching means remains in the second intake state and cannot be switched; 1. A control device for an engine, comprising: failure control means for changing engine control values in a direction that stabilizes combustion when the engine is detected. 3. In claim 1 or 2, the engine is a rotary piston engine, and the working chamber of each cylinder has a communication port that closes later than an intake port to which the intake passage is connected. is opened, the communication port of one cylinder and the communication port of the other cylinder are communicated with each other by a communication passage, and the control valve for opening and closing the communication passage is the intake state switching means of the engine. Control device.