JPS60230526A - Variable compression-ratio type engine - Google Patents

Abstract

PURPOSE:To eliminate the output shortage by making the mixed gas rich by increase-correcting the fuel injection amount when the compression ratio is varied in deceleration, in an engine in which the compression ratio is varied by varying the capacity of a combustion chamber. CONSTITUTION:The capacity of a combustion chamber 5, namely the compression ratio is varied by moving a piston 19 vertically by revolving a cam 20 by a motor 24. A compression-ratio position sensor 32 as compression-ratio detecting means is provided. Further, the operation-state detecting means such as air flow meter 10 and crank-angle sensor 33 are provided. Each output of these detecting means is input into a microcomputer 27, and an aimed compression ratio is set into the microcomputer 27 according to the engine operation state, and a motor 24 is controlled according to the deviation of the actual compression ratio from the aimed compression ratio. Further, in order to make the mixed gas rich for a prescribed time when the compression ratio is reduced in deceleration, the opening degree of an air bypass control valve 17 is reduced, and the fuel injection amount supplied from an injection valve 12 is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a variable pressure/i ratio engine in which the compression ratio of the engine can be changed by changing the volume of the combustion chamber, and in particular to a variable pressure/i ratio engine. The present invention relates to a variable compression ratio engine whose compression ratio changes according to operating conditions.

(Prior art) In order to improve output and reduce fuel consumption in internal combustion engines, increasing the compression ratio is effective because it improves thermal efficiency. A problem arises in that knocking occurs in certain areas. In order to solve this problem, an engine is known in which the compression ratio is changed by changing the volume of the combustion chamber depending on the rotational speed and load of the engine. moreover,
In such a variable compression ratio engine, a hydraulic chamber is formed on the back side of the piston for varying the volume of the combustion chamber, which also functions as a hydraulic cylinder, simplifying the hydraulic mechanism and making the device more compact. The improved version achieved was published in Japanese Unexamined Patent Publication No. 58-
It is described in No. 197439. However, in these conventional devices, when the compression ratio is changed from small to large during deceleration, for example, a delay in the operation of the compression ratio control system causes problems such as insufficient output and engine stalling.

(Objective of the present invention) Therefore, an object of the present invention is to provide a variable compression ratio engine that can effectively prevent the occurrence of insufficient engine output, engine stalling, etc. even when the compression ratio is changed during deceleration. The goal is to provide the following.

(Configuration of the present invention) In order to achieve the above object, the present invention is configured as follows. That is, the variable compression ratio engine of the present invention includes an operating state detecting means for detecting the operating state of the engine, a variable compression ratio means for changing the combustion chamber volume of the engine, and a signal from the operating state detecting means as input. compression ratio control means for outputting a control signal to the compression ratio variable means so that the compression ratio becomes a target compression ratio; It is characterized by being equipped with an air-fuel ratio correction to make it rich. In the present invention, for example, engine rotational speed, engine load, engine temperature, air-fuel ratio, transmission gear position, acceleration/deceleration state, intake air temperature, etc. are detected by the engine operating state detection means.

(Effects of the Present Invention) According to the present invention, when the compression ratio is increased during deceleration, the air-fuel ratio is corrected so as to enrich the air-fuel mixture. Therefore, high output can be obtained through combustion with a rich air-fuel mixture, and it is possible to effectively prevent a decrease in output due to the delay in operation of the compression ratio control system as described above. Therefore, problems such as engine stalling do not occur.

(Description of Embodiments) Referring to FIGS. 1 and 2, an engine E to which the present invention is applied includes a cylinder bore 2 in which a piston 1 reciprocates, and the cylinder 2 is connected to a cylinder block. 3 and a cylinder head 4. A combustion chamber 5 is formed in the upper part of the cylinder bore 2, and an intake port 6 opens into the combustion chamber 5. An intake valve 7 is combined with the intake port 6, and a spark plug 14 faces the opposite side of the intake boat 6 of the combustion chamber 5. An intake passage 8 is connected to the intake boat 6, and the intake passage 8 is provided with an air cleaner 9, an air flow meter 10, and a throttle valve 11 to form an intake system. Further, a fuel injector 12 is arranged near the intake port 6 of the intake passage 8. Further, an exhaust port (not shown) is opened in the combustion chamber 5 in a conventional manner, and an exhaust passage 13 is connected to the exhaust port to form an exhaust system. Further, a valve train system including a cam 15 for operating the liquid valve 7 engages with the intake valve 7 . A bypass passage 16 that bypasses the throttle valve 11 is connected to the intake passage 8, and an air bypass control valve 17 that controls opening and closing of the bypass passage 16 is provided. Furthermore, a sub-cylinder 18 that protrudes upward is continuously formed in the upper part of the combustion chamber 5, and a sub-piston 19 that slides inside the sub-cylinder 18 is disposed. has been done.

A stem 19a of the piston 19 projects outward from the sub-cylinder 18, and its tip abuts against the circumferential surface of the cam 20.

A disk 21 is attached near the tip of the stem 19a, and a spring 22 is in contact with this disk 21.
As a result, the piston 19 is urged upward in the figure. The cam shaft 23 of the cam 20 is connected to a drive motor 24
This causes the piston 19 to move up and down, thereby changing the volume of the combustion chamber 5, that is, the compression ratio, thereby forming a compression ratio variable means. .

Further, the lead wire 14a of the spark plug 14 is connected to one terminal of the distributor 25, so that a voltage signal from the ignition coil 26 is applied to the spark plug 14 at a predetermined timing. The device of this example includes a microcomputer (hereinafter referred to as microcomputer) 27 to control factors governing combustibility. Various information representing the operating state is input to the microcomputer 27. The intake temperature sensor 28 is attached to the air cleaner 9, detects the intake temperature, and sends a signal to the microcomputer 27. The microcomputer 27 also receives a signal from the air flow meter 10 manually. Further, the opening degree of the flow nottle valve 11 is detected by a throttle opening sensor 29 and similarly inputted to the microcomputer 27.

Furthermore, an air bypass control valve 17 is connected to an air bypass control valve 17 that detects the opening of the liquid valve 7.
A has a cooling water temperature sensor 31, a compression ratio position sensor 32 as compression ratio variable means for detecting the position of the piston 19 is located near the cam 20, and a crank angle sensor for detecting the crank angle is mounted on the crankshaft. 33, the transmission 34 is provided with a gear position sensor 35 that detects the gear position of the transmission, that is, a gear position, and an atmospheric pressure sensor 38 that detects atmospheric pressure. All signals are input to the microcomputer 27. Further, a signal from the ignition switch 36 is also input to the microcomputer 27 . The microcomputer 27 performs predetermined calculations on the input information representing these operating conditions, and controls the EGR valve 37, injector 12, ignition coil 26, and air bypass control solenoid 17.
a, a predetermined command signal is output to the drive motor 24 for compression ratio control and the transmission control motor 34a. As the transmission, for example, a belt type continuously variable transmission can be used, and as the control motor 34a, a normal type as described in Japanese Patent Application Laid-open No. 161346/1983 can be used. can.

Further, as shown in FIG. 3, a crank angle sensor 33
The signal is passed through a waveform shaping circuit 39, shaped into a waveform, and sent to a central processing unit (hereinafter referred to as CPU) 40. Signals from other various sensors are sent to the A/D converter 41
The signal is converted into a digital signal and input to the CPU 4'0.

A signal Si from an ignition switch 36 is also manually input to the microcomputer 27, and when the switch 36 is ON, the signal Si becomes 1, and when it is OFF, the signal Si becomes 0. The microcomputer 27 is a ROM in which predetermined constants are written.
41, and a RAM 42 for writing and reading information representing the operating state, calculation results, etc. from each sensor.

Further, the microcomputer 27 includes a counter 1 (43) that constantly counts the time, and can use the time as information as necessary. The CPU 40 determines whether the E, C, and R controls should be performed 71 based on various human power information, and outputs the EGR signal Se. The EGR signal Se is sent to the solenoid of the EGR valve 37 via the solenoid drive circuit 44 to control the opening and closing of the liquid valve. When the signal Se is 1, EGR control is performed and the signal S
e power (EGR control is stopped when it is 0. Microcomputer 27
is equipped with a counter 2 (45) for controlling fuel injection timing and injection time, and the injection (word Ti is
The injector drive circuit 4 via the counter 2 (45)
6, the injector 12 is operated manually. moreover,
The microcomputer 27 has a counter 3 for controlling ignition timing.
(, 47), and the ignition timing signal Ts is sent to the counter 3 (47), which sends an ignition signal to the spark plug 14 at a predetermined timing via the ignition circuit 48, ignition coil 26, and distributor 25. It's starting to happen. The CPU 40 also determines whether or not to supply air to binomass the throttle valve 11, and its control signal Pb is
The solenoid drive circuit 49 is operated manually. The solenoid drive circuit 49 operates the solenoid 17a of the air pressure control valve 17 in accordance with the control signal Pb.
Outputs valve opening/closing command signals. In this case, the signal p
When b is 1, the bypass air increases, and when b is 0, it decreases. The microcomputer 27 also includes a motor drive circuit 50 to control the operation of the drive motor 24 for compression ratio control, and this motor drive circuit 50 receives two control signals M1.
, M2. signal,
The values of Ml and M2 and their control details are shown in Table 1.

Table 1 Also, the gear ratio control motor 34a of the transmission 34 is operated by a motor drive circuit 51, and this motor drive circuit 51 is controlled by control signals M3 and M4. ing. The relationship between the values of signals M3 and M4 and the gear ratio is as shown in Table 2.

Table 2 Also, the control signal Sp is manually inputted to the controller, that is, the power supply circuit 52 of this microcomputer 27, so that the controller is turned ON the first time the signal S1 from the ignition switch 36 is turned on. However, unless the signal Sp is set to O, it will not turn off.

In the compression ratio control device having the above configuration, one of the compression ratio control
Let's discuss an example.

The programs shown in the flowcharts of FIGS. 3A to 3E are basic programs that are normally repeatedly executed when the ignition switch 36 is ON and the engine is in a complete combustion state, that is, under normal engine operating conditions. This program controls the compression ratio change, calculates the correction amount of ignition timing, fuel injection timing and injection amount, transmission gear ratio deviation, bypass air valve opening deviation, and also calculates the transmission gear ratio deviation. , generates a command signal for changing the bypass valve opening degree and the EGR valve opening degree. The program shown in the flowchart of FIG. 5 is an included routine that is executed by interrupting the above basic program every time the crank angle reaches TDC, and calculates the TDC period of the engine and gives instructions for fuel injection and ignition. Generate a signal.

In the figures, the following symbols are used to represent constants or variables.

In the basic program, the engine rotation speed Ne is calculated from the TDC period T and flr (SS'2) calculated in the included routine (S4).

Then, various data representing the operating state are read (35 to S9). Next, the ratio Qa/Ne of the engine speed Ne to the intake air amount Qa and the engine speed Ne
The basic quantities of the compression ratio and other combustibility governing factors corresponding to the operating state are read out from the map created in relation to the above (810-512). This map is
For example, the position value PC[l of the piston 19 that provides the basic compression ratio is as shown in FIG. According to this map, the area below the output characteristic curve a is divided into a plurality of small areas, and the basic compression ratio position value PCB is set according to each area. This value P. Basically, B is set to increase as the rotational speed increases, and to decrease as the load increases. In the diagram! The area indicated by is the value P. B is relatively small, the area indicated by h is relatively large, and the area indicated by m is set to an intermediate value. A similar map is prepared for the basic fuel injection amount Tj8 and the basic ignition timing TSH, and these basic amounts are set based on them. Next, after a correction operation is performed on the basic compression ratio position value Pcn set by the above map (813-523), a position value Pco of the piston 19 that provides the target compression ratio is calculated (S24). The correction is based on the engine coolant temperature Tw, the presence or absence of EGR control indicated by the EGR signal Se, the atmospheric pressure Pt, and the intake air temperature T.
This is done by giving different correction coefficients depending on a.

In this case, the engine temperature correction coefficient Cpcw changes with the characteristics shown in FIG. 6 in relation to the engine cooling water temperature Tw. Similarly, the altitude correction coefficient Cpcp has the characteristics shown in Fig. 7 in relation to the atmospheric pressure Pt, and the intake air temperature correction coefficient Cpca has the characteristics shown in Fig. 8 in relation to the intake air temperature Ta. Given. Therefore, when the intake air temperature Ta, that is, the outside air temperature is high, and when the cooling water temperature Tw is high, the value Pco becomes smaller, and the lower the atmospheric pressure Pt, that is, the higher the altitude, the value Pco becomes smaller.
co becomes larger. Further, when EGR is performed, the value of the target compression ratio position value Pco becomes small. In this example, the target compression ratio position value Pco has three different values, P cl and P c2, depending on the magnitude of the calculated value.
, Pc3. Furthermore, the engine speed Ne, the intake air amount Qa and the engine speed Ne
The air bypass control valve 17 in the operating state is determined from a map prepared in advance based on the ratio Qa/Ne.
The basic opening degree, that is, the basic air bypass valve position value Pan is calculated (S31). Furthermore, a basic value for setting the gear position of the transmission 34, ie, a basic T/M gear position value Pgn, is calculated using the same map (S32). Next, the position of the piston 19 that provides the actual compression ratio, that is, the deviation ΔPc between the actual compression ratio position value Pc and the target compression ratio position value Pco is calculated (S33). According to the value of this deviation ΔPc, the compression ratio change control signals M1 and M2 are set to predetermined values and output (S35.541). When the target compression ratio position value Pco is positive, that is, when increasing the compression ratio, the control signals are set to M1=1 and M2=1, and a correction value is given so that the ignition timing is advanced. (S36), and a correction value is given to increase the bypass air (S3'i').

Furthermore, a correction value is given to increase the fuel injection amount (338). On the other hand, when the target compression ratio position value Pco is negative, the control signals are set to Ml-1, M2-0,
Unlike the case of increasing the compression ratio, a correction value is given so that the ignition timing is delayed, and a correction value is given so that the bypass air is decreased (543). Then, a correction value that increases the fuel injection amount is given. The position of the transmission gear is set to the low speed side (S45).

Next, considering such a correction command signal, the transmission 34
A target position value Pgo of the bypass air valve is calculated (398), and a target position value Pao of the bypass air valve is calculated (S9
9). Further, the ignition timing Ts and the injection amount Ti are calculated (S100, 5IOI).

In this case, although the control signals M1 and M2 for changing the compression ratio are output to the drive motor drive circuit 50, the compression ratio is in a transitional state where it has not yet reached the target compression ratio.

Next, the deviation from the target value of gear 1-hi of the transmission 34 is calculated (5102). Based on this result, the gear ratio is corrected (3103-S10.6.).

Then, regarding the opening degree of the air bypass control valve 17 that determines the amount of air that bypasses the throttle valve 11, the deviation between the target opening degree PaO and the actual opening degree Pa is calculated (S107), and based on the result, the opening degree is calculated. The degree is corrected (3108-5Lio).

When the actual compression ratio matches the target compression ratio, that is, when the compression ratio change is completed, the flammability governing factors, ignition timing, fuel injection amount, etc., are changed depending on whether the compression ratio has decreased or increased. A predetermined correction value is given to the amount of bypass air for a certain period of time. That is, when the compression ratio increases, the ignition timing is shifted to the advanced side, the amount of bypass air is decreased, and a correction amount is given that reduces the amount of injection (856 to 558). Also, when the compression ratio decreases, the opposite correction amount is given (859~
561).

These correction values are designed to attenuate over time (846-856).

Furthermore, when the compression ratio is changed in an acceleration/deceleration state, corrections are made to the flammability governing factors for a certain period of time in a certain operating region (863 to 584); , corrections are made to reduce bypass air, increase fuel injection amount, and shift ignition timing to the retarded side. Furthermore, a correction amount is given to change the gear position of the transmission to a lower speed side. On the other hand, during deceleration, a correction amount is given that increases the amount of bypass air and fuel injection and changes the ignition timing to the advanced side.

Finally, the combustibility governing factors are determined by comprehensively taking into account the basic amount from the map, the correction amount due to compression ratio change, and the correction amount due to acceleration/deceleration (S100-5102).

The ignition timing signal TS and fuel injection signal T1 thus determined serve as command signals for the spark plug 14 and the injector 12 when the included routine is executed.

Then, when the ignition switch 36 is turned OFF, the target compression ratio position is set to the low compression ratio position at the time of starting (5ill), and an operation is performed to lower the compression ratio until it reaches the 1 target value (S10 to 5102). When the ratio falls to the starting position, the compression ratio control motor is stopped (S115), and the controller power supply,
That is, the power of the control system is turned off (S1
16).

According to this example, as described above, if the wind/frost ratio changes during deceleration, a correction is made to increase the fuel injection amount. As a result, the air-fuel mixture is enriched, and high output can be obtained using the fuel. Therefore, even in the case described above, that is, even if there is an operation delay in the compression ratio control system, the shortage of output can be resolved. by this,
Problems such as engine stalling can also be solved at the same time.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of an engine to which the present invention is applied, Fig. 2 is an explanatory diagram of a microcomputer according to an embodiment of the present invention, Fig. 3A,
3B, 3C, 3D, 3E, and 4 are flowcharts showing the details of control according to one embodiment of the present invention, and FIG. Graph showing the relationship with compression ratio, Figure 6 is a graph showing the relationship between cooling water temperature and compression ratio position engine temperature correction coefficient, and Figure 7 is a graph showing the relationship between atmospheric pressure and compression ratio position altitude correction coefficient. , FIG. 8 is a graph showing the relationship between intake air temperature and compression ratio position intake temperature correction coefficient. ■... Piston, 3... Cylinder block, 4... Cylinder head, 5...
・Combustion chamber, 8...Intake passage, 10...
Air flow meter, 18...Sub cylinder, 1
9...Sub-piston, 27...Microcomputer, 33...Crank angle sensor, 40...
・CPU, 41...A/D converter. Figure 3E Figure 4 Figure 5 Figure 7 Figure 8

Claims (1)

[Claims] an operating state detecting means for detecting the operating state of the engine; a compression ratio variable means for changing the combustion chamber volume of the engine; Compression ratio control means for outputting a control signal to the ratio variable means; and air-fuel ratio correction means for enriching the air-fuel mixture for a predetermined period of time in response to a change in the compression ratio when the compression ratio is increased during deceleration. A variable compression ratio engine.