JPS62142859A - Ignition timing control device for variable compression ratio internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent the occurrence of shock due to switching of a compression ratio, by a method wherein, in a device in which the magnitude of a compression ratio is varied with an operating condition, and an ignition timing is mapped, an ignition timing prevailing during switching of a compression ratio is corrected based on a demand. CONSTITUTION:An internal combustion engine 1 has a control mechanism 2 which varies a compression ratio depending upon an operating condition. In this case, a signal responding to the compression ratio of the internal combustion engine 1 is generated by means of a means 3, the set value of an ignition timing responding to the compression ratio of an internal combustion engine 1 is computed by a means 4, and a switching point of time is detected according to the magnitude of a compression ratio through the working of a means 5. A demand ignition timing set by the means 4 is corrected at the switching point of time of a compression ratio by means of a means 7, and ignition is effected at an ignition timing set by a control device 8. This constitution corrects an ignition timing prevailing during switching of a compression ratio is corrected based on a demand to prevent the occurrence of shock due to switching of a compression ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ignition timing control device for an internal combustion engine in which the compression ratio is variable according to operating conditions.

[Prior Art] In an automatic cycle internal combustion engine, increasing the compression ratio improves combustion efficiency, improves fuel consumption rate, and increases output. However, when the compression ratio is increased, knocking becomes more likely to occur.

Therefore, the compression ratio is made as high as possible within a range where non-king does not occur. When the compression ratio changes, the required value of the ignition timing also changes, so the ignition timing is controlled according to the compression ratio. Although there are various methods of varying the compression ratio, there is one that mechanically changes the stroke of the piston itself (for example, see Japanese Patent Laid-Open No. 58-91340).

[Problem that the invention seeks to solve]

In devices where the compression ratio is made variable by mechanically changing the stroke of the piston, switching of the compression ratio occurs in steps between high and low set compression ratios.

Therefore, the engine torque suddenly changes at the time of switching, which may cause a shock.

An object of the present invention is to prevent the occurrence of shock when switching the compression ratio in an internal combustion engine having a variable compression ratio. In addition, as related technology to this invention, Japanese Patent Application Laid-open No. 1983
There is No.-230522.

[Means for solving problems]

In FIG. 1, an internal combustion engine 1 includes a compression ratio control mechanism 2 that varies the compression ratio depending on operating conditions.

The ignition timing control device for an internal combustion engine according to the present invention includes a compression ratio detection means 3 that generates a signal according to the compression ratio of the internal combustion engine, and a compression ratio detection means 3 that is connected to the compression ratio detection means 3 and adjusts the ignition timing according to a request for the compression ratio of the engine. An ignition timing setting means 4 that calculates a set value, a means 5 connected to the compression ratio detection means 3 and detecting the point at which the compression ratio changes between high and low, and a means 5 that detects when the compression ratio changes from high to low; The ignition timing control device 8 includes an ignition timing correction means 7 that corrects the ignition timing at the point in time, and an ignition timing control device 8 that causes ignition to occur at the set ignition timing.

[For production]

The compression ratio detection means 6 detects whether the compression ratio of the internal combustion engine 1 is a high compression ratio or a low compression ratio. The ignition timing setting means 7 sets the ignition timing according to the detected compression ratio request. The compression ratio switching detection means 5 detects the point in time when the compression ratio is switched between high and low levels. The ignition timing correction means 7 corrects the ignition timing upon request when switching the compression ratio. The ignition timing control device 8 controls the engine so that a set ignition timing is obtained.

〔Example〕

In FIG. 2, 10 is the main body of a four-cylinder internal combustion engine, and 12
14 is a combustion chamber, 14 is a spark plug, 16 is an intake pipe, and 18 is an air flow meter. 19 is a distributor.

FIG. 3 shows a detailed longitudinal section of the engine of one cylinder, with 20 being a cylinder block, 21 being a cylinder head, 22 being a piston, 23 being a connecting rod, and 2
4 indicates a piston pin, and 25 indicates a crankshaft.

This internal combustion engine has a variable compression ratio mechanism which will be described below. That is, an eccentric bearing 27 is rotatably fitted into an opening 23a formed at the upper end of the connecting rod 23, and the piston pin 24 is inserted into the eccentric bearing 27. The eccentric bearing 27 has a wall thickness that changes in the circumferential direction. A radial lock pin retaining hole 28 is formed in the thickest portion of the eccentric bearing 27. On the other hand, a lock pin storage hole 29 is opened in the radial direction in the opening 23a at the upper end of the connecting rod 23 that accommodates the eccentric bearing 27. The lock pin engagement hole 28 of the eccentric bearing 27 and the lock pin storage hole 29 at the upper end of the connecting rod 23 are located in the illustrated position where the thickest part of the eccentric bearing faces below the connecting rod axis. They are based on each other. lock pin 3
0 is fitted into the lock pin storage hole 29 and can freely move in and out of the lock pin engagement hole 28.

Two hydraulic passages are installed to move the lock pin 30 into and out of the lock pin engagement hole 28. That is, two arcuate oil grooves 31 and 32 are formed at intervals in the circumferential direction on the inner surface of the opening 23d through which the crankshaft 25 is inserted at the lower end of the connecting rod 23. One oil groove 31 communicates with the lower part of the lock pin storage hole 29 via an oil hole 23e in the connecting rod 23. The other oil groove 32 opens into an arcuate oil groove 34 on the inner peripheral surface of the opening 23a at the upper end of the connecting rod through an oil hole 23f formed in the connecting rod 23 independently of the oil hole 23e. The oil groove 34 is formed in the radial hole 2 formed in the eccentric bearing 27.
It communicates with the upper part of the lock pin retaining hole 28 via 7b.

An oil hole 25a is formed in the crankshaft 25.
One end 25a-1 of a extends to an opening 23d at the lower end of the connecting rod. Therefore, during rotation of the crankshaft 25, the oil holes 25a are alternately communicated with the oil grooves 31 and 32. The other end 25a-2 of the oil hole 25a extends to the opening 20a of the journal portion 201 of the cylinder block 20. Two independent arcuate oil grooves 37 and 38 in angular directions similar to those described above are formed in the opening 20a, and the oil hole 25a is inserted into the oil groove 37 while the crankshaft 25 is rotating.
．． 38 alternately. And oil hole 2
The position of 5 is set as follows: crankshaft 2
5, the oil hole 25a alternately communicates between the oil groove 37 of the journal portion and the oil groove 31 of the connecting rod, and the oil groove 38 of the journal portion and the oil groove 32 of the connecting rod.

The oil grooves 37 and 38 are connected to a high compression ratio oil passage 40 via oil holes 20b and 20c formed in the cylinder block 20.
and a low compression ratio oil passage 41.

In FIG. 2, the population 40 of the high compression ratio oil passage 40 is
a and the inlet 41a of the low compression ratio oil passage 41 are connected to a solenoid-driven hydraulic switching valve 45 via hydraulic piping 43.44.
connected to. The hydraulic switching valve 45 is connected to the high compression ratio oil passage 4
Hydraulic pressure from the oil pump 46 is selectively supplied to the 0 or low compression ratio oil passage 41. 47 is an oil tank. The hydraulic switching valve 45 is driven as follows by a control circuit that will be described later. When the solenoid 45a is demagnetized, the oil pressure from the oil pump 46 is transferred to the pipe 43.
The high compression ratio oil passage 41 is introduced into the high compression ratio oil passage 4° through a pipe 44, while the low compression ratio oil passage 41 is communicated with an oil tank 47 through a pipe 44.

Therefore, the oil pressure is transmitted from the oil hole 20b (Fig. 4) to the oil groove 37 of the journal portion 20'.
5a communicates with the oil groove 31 of the connecting rod 23, the oil hole 23 in the connecting rod 23
e acts on the lower end of the lock bin 30. On the other hand, the oil pressure at the upper end of the lock bin 30 escapes to the oil tank 47 through the following path. That is, the lock bin engagement hole 28 is the oil hole 27b,
23f, the oil groove 32 of the connecting rod 23
When the oil is communicated with the oil groove 38 of the journal part through the oil hole 25a of the crankshaft 25, it is communicated with the oil hole 20c, and from there, it is communicated with the tank 47 via the passage 41, the piping 44, and the switching valve 45. In this way, the hydraulic pressure acts on the lower end of the lock bin 30, and the pressure is released at the upper end, so the lock bin 3o is urged upward toward the lock bin retaining hole 28, and is fitted into the lock bin 28. 30
is maintained in this state by In this state, the maximum eccentric part of the eccentric bearing 27 is in the lower position, so the position of the piston pin 24 is relatively high.This increases the effective length of the connecting rod 23, so a high compression ratio can be set. be done.

When a low compression ratio is to be selected, the solenoid 45a of the hydraulic switching valve 45 is energized. Then, the hydraulic pump 46 is in turn communicated with the low compression ratio hydraulic passage 41 via the piping 44, while the high compression ratio hydraulic passage 40 is communicated with the oil tank 47 via the piping 43. The hydraulic pressure introduced into the low compression ratio hydraulic passage 41 passes through the oil hole 20c, and when the oil groove 38 is communicated with the oil groove 32 by the oil hole 25a of the crankshaft,
It communicates with the oil hole 23f of the connecting rod, and the oil hole 2
7b and acts on the upper surface of the lock bin 30 from the lock bin engaging hole 28. On the other hand, the oil pressure in the lock bin storage hole 29 is communicated from the oil hole 23e to the oil hole 20b when the oil groove 31 is connected to the oil groove 37 by the oil hole 25a, and from there the piping 43 and the oil pressure switching valve 45 are connected. Intermediate oil tank 4
Hydraulic pressure is released at 7. In this way, hydraulic pressure is applied to the upper end of the lock bin 30 and pressure is reduced at the lower end, so the lock bin 30
0 descends and exits from the lock bin retaining hole 28. In this manner, the eccentric bearing 27 is in a stable state, with the maximum eccentric portion located on the upper side near the top dead center where the most force is applied. Thus, the position of the piston pin 24 is relatively lowered, which reduces the effective connecting rod length and results in a lower compression ratio setting.

As described above, in this embodiment, by providing the eccentric bearing 27 and making the lock bin 30 freely engageable and detachable, a desired high and low compression ratio can be obtained. Note that the compression ratio control mechanism is not limited to this embodiment, and may be any other known mechanism.

According to this invention, the variable compression ratio mechanism is driven to obtain the optimum compression ratio by detecting the operating conditions of the engine, and the ignition timing is controlled to the ignition timing required by the compression ratio by detecting the compression ratio. , and a control circuit 50 that controls the ignition timing at the time of switching the compression ratio to be modified according to a request.
will be installed (Figure 2). This control circuit 50 is configured as a microcomputer system, and has a central processing unit (
CPU) 51 and read-only memory (ROM) 52
, a random access memory (RAM) 53, an input/output board 54, an A/D converter 55, and a bus 57 connecting these elements.

The following sensor groups are provided to detect engine operating conditions. The distributor 19 is provided with a first crank angle sensor 56 and a second crank angle sensor 57.

The first crank angle sensor 56 is connected to the distributor shaft 19
The second crank angle sensor 57 is installed facing the detection piece 58 on the top a and generates a pulse signal NE every 30'' of the crankshaft 15, for example, and this is used to know the engine rotation speed. Detection piece 5 on distributor shaft 19a
9, and the crank angle shaft 15, for example, 720
A pulse signal G is generated every degree, and this serves as a reference signal.

The aforementioned air flow meter 18 generates an analog signal Q corresponding to the amount of intake air introduced into the engine.

Although other sensors are also provided, they are not directly related to this invention, and therefore their description will be omitted.

The control circuit 50 executes necessary calculations based on the operating conditions detected by each sensor, and outputs a compression ratio control signal and an ignition signal from the input/output boat 54. Ignition control device 6
6 consists of an ignition control circuit (igniter) and an ignition coil, and the ignition control circuit is connected to an input/output boat 54 to receive and receive ignition signals. On the other hand, the ignition coil is connected to the center electrode of the distributor 19, and high voltage is distributed to the spark plugs 14 of each cylinder according to the rotation of the distribution shaft 19a. The input/output boat 54 is further connected to a solenoid 45a of a hydraulic switching valve 45, and compression ratio switching control is executed in accordance with a compression ratio control signal.

The operation of the control circuit 50 will be explained below using a flowchart. The program to realize this operation is in ROM5.
2 is stored in a predetermined area.

FIG. 5 shows a compression ratio control routine. This routine may be a time interrupt routine that is executed at predetermined time intervals. In step 70, the engine rotational speed NE and the intake air amount to rotational speed ratio Q/NE, which is a representative value of the engine load, are input. Engine speed NE is the 1st
It is assumed that calculation is performed using a well-known method from the interval of pulse signals every 30'' of crank angle from the crank angle sensor 56, and that the intake air amount to revolution speed ratio Q/NE is also calculated in a separate routine.

In step 71, the compression ratio to be set is determined from the engine rotational speed NE and the intake air amount to rotational speed ratio Q/NE.

That is, in a predetermined area of the ROM 52, there is a map indicating which compression ratio, high or low, should be set for the combination of the rotation speed NB and the intake air amount-to-rotation speed ratio Q/NE. The CPU 51 selects a desired compression ratio from the input actually measured NE and Q/NE.

In step 72, it is determined whether the compression ratio determined in step 71 is a high compression ratio. When the compression ratio to be selected is a high compression ratio, the process advances from step 72 to step 73, and the signal level applied from the input/output boat 54 to the solenoid 45 of the hydraulic switching valve 45 is turned OFF. Therefore, the hydraulic switching valve 4
5 assumes the right position in FIG. 2, and supplies hydraulic pressure to the inlet 40a of the high compression ratio hydraulic passage 40, and the inlet 41a of the low compression ratio hydraulic passage 41 is communicated with the tank 47.

Therefore, as described above, the lock pin 30 is urged upward, and the lock pin 30 engages with the lock pin retaining hole 28.
The eccentric bearing 27 is held in a position where its maximum eccentric portion faces downward, the effective length of the connecting rod 23 is increased, and the compression ratio is set to be large. At step 74, flag F is set.

As a result of the map search, if the compression ratio to be selected is a low compression ratio, the process proceeds from step 72 to step 75, where an ON signal is applied from the output port 54 to the solenoid 45a of the hydraulic pressure switching valve 45. Therefore, the switching valve 45 takes the left position in FIG.
7. Therefore, the lock bin 30 is urged downward and is separated from the lock pin retaining tag 28. As a result, the eccentric bearing 27 is released from the restraint state, and the maximum eccentricity, which is a stable state, is located on the upper side. In this way, the effective length of the connecting rod 23 is shortened and the compression ratio is set small. At step 76, flag F is reset.

Figure 6 shows the ignition timing control routine, and this routine is performed at T
This is a crank angle interrupt routine that is started when the crank angle sensors 56 and 57 detect the angle from DC. In step 77, it is determined whether the current operating conditions are such that the engine should be operated at a high compression ratio. Is this determination step more detailed than the step in Figure 5? 0,71.72
It is determined by map search whether the high compression ratio condition or the low compression ratio condition exists. When it is determined in step 77 that the low compression ratio condition exists, the process proceeds to step 78, where a basic ignition timing θBASE is calculated based on the ignition timing map for low compression ratio. As is well known, the basic ignition timing is a map of ignition timing values suitable for low compression ratios for combinations of rotational speed NE and intake air amount to rotational speed ratio Q/NE, and is actually measured. NE and Q
The calculation of θBASE for /NE is performed.

In step 79, the ignition timing θ is determined by subtracting the retardation correction amount Δθ″ from the basic ignition timing θBASE. Since it is not related to this, the explanation will be omitted.

In step 80, an ignition command is output from the output port 54 to the ignition control circuit 66. Therefore, as is well known, ignition is executed at the calculated ignition timing θ.

If it is determined in step 77 that the high compression ratio condition is present, the process proceeds from step 77 to step 81, in which basic ignition timing θBASH is calculated from the ignition timing map for high compression ratio. As mentioned above, the basic ignition timing is a map of ignition timing values suitable for high compression ratios for combinations of rotational speed NE and intake air amount to rotational speed ratio Q/NE, and is actually measured. The calculation of θBASE for NE and Q/NE is performed.

In step 82, it is determined whether flag F=1. The flag F is set so that the solenoid 4 of the switching valve 45 takes a high compression ratio.
This is a flag that is set when 5a is turned off. Therefore, when F=0, it means that the engine is switching from a low compression ratio condition to a high compression ratio condition. At this time, the process proceeds to step 83, and an initial value C is entered into the ignition timing retardation correction amount Δθ at the time of switching the compression ratio. In step 84, the basic deepening timing θBASE minus Δθ is the ignition timing θ.
It is said that That is, at the time when the compression ratio is switched from a low compression ratio to a high compression ratio, the ignition timing is retarded by Δθ from the required ignition timing.

FIG. 7 shows a routine for reducing the retard angle correction amount when switching the compression ratio, and this routine is a time interrupt routine that is executed at predetermined time intervals. In step 90, Δθ is decremented by α. In step 90, it is determined whether Δθ has decreased to O. If it has decreased to 0, Δθ is fixed to O in step 92, and if it is determined in step 91 that it has not decreased to 0, step 92 will be detoured. Each time the routine shown in Figure 7 is passed, the retard angle correction amount gradually becomes smaller, and finally Δθ=0, and when a predetermined period of time has elapsed since the compression ratio was switched from a low compression ratio to a high compression ratio. , the ignition timing will take a value that meets the requirements of the engine.

FIG. 8 schematically shows the ignition timing control operation in the above embodiment. Assuming that the engine is initially under operating conditions suitable for a low compression ratio, the required ignition timing at that time is assumed to be θ0. Assuming that the operating conditions change to operating conditions suitable for a high compression ratio at time tA, at the moment of the change, the ignition timing is controlled to a value delayed by Δθ from the required ignition timing θ1 at the high compression ratio. Then, as time passes, Δθ decreases by α (step 90 in Figure 7),
The ignition timing gradually approaches the required value θ1 during high compression ratio operation, and is finally controlled to θ1 (time tB). The step width of the retard angle correction is selected to be an optimum value.

In this embodiment, when the operating conditions switch from a low compression ratio to a high compression ratio, shock is prevented by setting the ignition timing to a value on the delayed side of the value suitable for the high compression ratio and then gradually advancing it to the optimum value. be able to. In other words, operation at a high compression ratio corresponds to when the engine is under low load, but when the compression ratio is switched, there is a temporary increase in torque, which causes a shock. to suppress coming out. be able to.

In the embodiment, the ignition timing is corrected in stages at the time of switching, but it may be fixed to one intermediate value as indicated by the broken line l in FIG.

〔Effect of the invention〕

According to the present invention, in a system in which the compression ratio is varied high or low depending on the operating conditions and the ignition timing is map-controlled under each compression ratio condition, the ignition timing at the time of switching the compression ratio is corrected according to the request. It is possible to prevent shock from occurring due to ratio switching and improve drivability.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of this invention. FIG. 2 is a configuration diagram of an embodiment in which the compression ratio is detected at the maximum combustion pressure. FIG. 3 is a detailed longitudinal sectional view of the combustion chamber portion of one cylinder. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. 5, 6 and 7 are flowcharts showing the operation of the control circuit in FIG. 2. FIG. 8 is a timing chart showing the operation of the control circuit. 10... Engine body 12... Combustion chamber 14... Spark plug 18... Air flow meter 19... Distributor 22... Piston 23... Connecting rod 24... Piston pin 25... Crankshaft 27... Eccentric bearing 29... Lock bin engagement hole 30... Lock pin 40... Hydraulic passage for high compression ratio 41... Hydraulic passage for low compression ratio 45... Hydraulic switching valve 50 ...Control circuit 56,57...Crank angle sensor 66...Ignition circuit Fig. 5 Fig. 6 Fig. 7 Fig. 8

Claims (1)

[Claims] In an ignition timing control device for an internal combustion engine having a compression ratio control mechanism that varies the compression ratio high or low according to operating conditions, a compression ratio detection means that generates a signal according to the compression ratio of the internal combustion engine;
ignition timing setting means connected to the compression ratio detection means to calculate a set value of ignition timing in accordance with a request for the compression ratio of the engine; means connected to the compression ratio detection means to detect when the compression ratio switches between high and low; An ignition timing control device for an internal combustion engine, comprising an ignition timing correction device that corrects the required ignition timing set by the ignition timing setting device at the time of compression ratio switching, and an ignition timing control device that causes ignition to occur at the set ignition timing. .