JPS6312837A - Internal combustion engine with turbocharger having variable compression ratio device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of sudden fluctuation in engine output torque during switching of a compression ratio, by a method wherein a variable compression ratio device is forced to perform supercharging when it is actuated on the low compression ratio side, meanwhile, it is forced to stop supercharging or widely reduce supercharging when it is actuated on the high compression ratio side. CONSTITUTION:An eccentric bearing 6 is rotatably located between a piston insertion hole 5, formed in the end part of a connecting rod 3 through which a crank shaft and a piston 2 are interconnected, a piston pin 4. Through engagement of a lock pin 8 with a lock pin engaging hole 9 formed in the eccentric bearing 6, the piston 2 is displaced to a high and a low stage, and a compression ratio is formed so that it is switchable in 2 stages of the one being a high and the other being a low stage. In this case, when a low compression ratio is selected, a vacuum switching valve 47 is opened by means of an ECU 23 and an actuator 40 is driven to close a waist gate valve situated to a turbocharger 31 to perform turbocharging. Meanwhile, when a high compression ratio is selected, control is effected so that, reversely, supercharging is stopped or reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a turbocharger and compression ratio control structure in a turbocharged internal combustion engine equipped with a variable compression ratio device.

[Conventional technology]

There are two types of supercharging means for internal combustion engines: one is a turbocharger that uses exhaust gas discharged from the engine, and the other is a mechanical supercharger that uses the rotational driving force of a crankshaft.

Furthermore, as a device for varying the compression ratio in an internal combustion engine, a compression ratio variable mechanism using an eccentric bearing has been known (for example, Japanese Patent Application Laid-Open No. 58-91340 and Japanese Patent Application Laid-open No. 58-172431).

Examples of prior art related to turbocharged internal combustion engines related to the present invention include, for example, Japanese Patent Publication No. 47-43372;
Japanese Unexamined Patent Publication No. 55-164727 is known.

The engine disclosed in the above-mentioned Japanese Patent Publication No. 47-43372 divides the intake passage leading to the inlet of the compressor of the turbocharger and the intake passage connecting the compressor to the engine by a shunt on the upstream side of the throttle valve. A switching valve is provided at the branch point between the intake passage and the shunt passage, and this switching valve is linked to the throttle valve that adjusts the amount of intake air, so that when the throttle valve opens to a low degree, the passage on the compression ratio side is closed. is configured to do so.

Further, the engine disclosed in Japanese Patent Publication No. 55-164727 is provided with a passage that bypasses the compressor of the turbocharger and a passage that bypasses the turbine of the turbocharger, and in both bypass passages, Each valve is equipped with a valve whose opening degree is controlled based on the operating conditions of the engine.

However, all of the above-mentioned engines are turbocharged internal combustion engines, and are not engines equipped with a variable compression ratio device.

[Problem that the invention seeks to solve]

In a turbocharged internal combustion engine, output is required at high loads, so the supercharging is increased at high loads, and the supercharging pressure is reduced at light to medium loads. However, this turbocharged internal combustion engine has a problem in that as the load increases, the engine intake air amount and pressure increase, making knocking more likely to occur. Therefore, supercharging (
It is thought that non-king can be easily prevented by switching the compression ratio into two levels, high and low, depending on the load (load).

However, the problem is how to arrange the switching of the compression ratio and the supercharging characteristics. In other words, when changing the compression ratio in stages, if the boost pressure was simply changed continuously according to the load, there would be a problem that the output torque would fluctuate suddenly when the compression ratio was changed. Live. In other words, as shown in Fig. 8, while the supercharging pressure P2 changes smoothly, the compression ratio switches from a high compression ratio to a low compression ratio at a certain position ε2, so the engine output torque T2 smoothly changes. There is a problem in that the drivability is significantly deteriorated without any change in the drivability.

In order to solve the above problem, the present invention prevents sudden fluctuations in engine output torque that occur when switching the compression ratio by appropriately controlling supercharging according to the compression ratio in a turbocharged internal combustion engine. The aim is to significantly improve the driver's ability to take the ball.

[Means for solving problems]

A turbocharged internal combustion engine equipped with a variable compression ratio device of the present invention in accordance with this purpose is provided with a variable compression ratio device in the turbocharged internal combustion engine, and an electronically controlled bag of the variable compression ratio device is configured to provide a low compression ratio. It has a control function that sometimes performs supercharging and stops or significantly reduces supercharging when the compression ratio is high.

[Effect]

In a turbocharged internal combustion engine equipped with a variable compression ratio device configured as described above, the compression ratio is switched to a high compression ratio when the load is light. In this case, supercharging is stopped or significantly reduced. That is, even if supercharging is stopped, the compression ratio is increased, so combustion efficiency is improved and fuel consumption is reduced.

When the load is high, a large amount of air is introduced into the combustion chamber, so the compression ratio is switched to low compression to prevent knocking. Therefore, high output can be obtained while suppressing the occurrence of knocking.

Also, when the compression ratio is low, the supercharging is controlled by the command from the electronic side mW position to increase the output torque at the low compression ratio. iU
It becomes possible to make the magnitude of the torque just before switching the compression ratio and the torque immediately after switching the compression ratio match substantially the same value.

Therefore, as a result, large torque fluctuations at the time of compression ratio switching are prevented.

〔Example〕

Preferred embodiments of a turbocharged internal combustion engine equipped with a variable compression ratio device according to the present invention will be described below with reference to the drawings.

First Embodiment FIG. 1 shows a control system diagram of a turbocharged internal combustion engine equipped with a variable compression ratio device according to a first embodiment of the present invention. In the figure, a piston 2 is slidably fitted into a cylinder 1 of an internal combustion engine, and the piston 2 is connected to a connecting rod 3 via a piston pin 4.

The piston pin 4 is fixedly or rotatably supported in the piston pin hole of the piston 2.

Between the piston pin insertion hole 5 at the small end of the connecting rod 3 and the outer periphery of the piston pin 4, there is an eccentric bearing 6 whose wall thickness changes in the circumferential direction and whose inner and outer circumferential circles are eccentric from each other. is rotatably installed.

A lock pin storage hole 7 extending in the radial direction of the eccentric hair ring 6 is formed at a position of the connecting rod 3 corresponding to the eccentric bearing 6, and a lock pin 8 is slidably inserted into the cough hole 7 and is inserted into the hole 7. It is housed so as to be freely retractable from the eccentric bearing 8. On the other hand, in the eccentric bearing 6, a lock pin engagement hole 9 having a diameter that allows the lock pin 8 to move in and out is formed in a thicker portion in the radial direction. When the lock pin 8 engages with the lock pin engagement hole 9, the piston 2 is kept at a high position and a high compression ratio is achieved, and when the lock pin 8 is released, the eccentric hair ring 6 freely rotates and compresses. At top dead center, the piston is in a low position, creating a low compression ratio state. That is, in a turbocharged internal combustion engine equipped with this variable compression ratio device, the compression ratio can be switched between two levels, high and low.

Next, the drive structure of the lock pin 8 will be described. The lock pin storage hole 7 is connected to a lock pin locking hydraulic passage 10 and a lock pin unlocking hydraulic passage 11 with the lock pin 8 in between. Hydraulic passage 1
0 is opened at a position that urges the lock pin 8 in the direction of the eccentric bearing 6.

Further, a lock pin guide groove 12 is formed on the outer periphery of the eccentric bearing 6 at a position corresponding to the lock pin 8 and extends over the entire circumference in the circumferential direction, and the lock pin engagement hole 9 is provided in this groove 12. It is being

The hydraulic passage 1 provided in the connecting rod 3
0.11 are in communication with oil grooves 14 and 15 provided independently from each other on the circumference of the bearing at the large end of the connecting rod. The oil grooves 14 and 15 are connected to the crankshaft 1.
Oil grooves 18 provided independently from each other on the circumference of the journal bearing of the crankshaft/inner shaft
．． 19 so that they can communicate intermittently when the crankshaft 16 rotates.

The oil groove 18 can communicate with the lock pin locking hydraulic passage 10 via the oil groove 14, and the oil groove 19 can communicate with the lock pin unlocking hydraulic passage 11 via the oil groove 15.

A main oil passage 20 for high compression ratios and a main oil passage 21 for low compression ratios are provided in the cylinder block, and the main oil passage 20 for high compression ratios communicates with the oil groove 18, The main oil passage 21 communicates with the oil groove 19. The lubricating oil in the oil pan 132 is pumped up by the oil pump 26 and sent to either the high compression ratio main oil passage 20 or the low compression ratio main oil passage 21 via the switching valve 22.

The switching valve 22 is controlled by the ECU (electronic control unit) 2 according to the load.
When the load is medium or high, pressure oil is sent to the main oil passage 21 for low compression ratio, and when the load is light, pressure oil is sent to the main oil passage 20 for high compression ratio. controlled so that

The intake air iQ detected by the air flow meter 24 and the engine speed NE detected by the engine speed sensor 25 are input to the IECU 23, respectively. That is, the ECU 23 controls the intake air iQ and the engine speed NH.
The switching valve 22 is operated in response to an input signal to switch the compression ratio.

The ignition control device includes an igniter (ignition control circuit) 27 and an ignition coil (path shown), and the igniter 27 is connected to the output port of the ECU 23 to receive and receive ignition signals. The ignition coil is
It is connected to the center electrode of the distributor 28, and high voltage is distributed to the spark plugs 29 of each cylinder according to the rotation of the distribution shaft.

The ECU 23 also includes a waste gate pal 7, which will be described later.
'39wo fdl? A vacuum switching valve (VSV) 47 is connected.

A knock sensor 30 is attached to the cylinder block 1 to detect non-king occurring in the combustion chamber, and the knock sensor 30 is connected to an input port of the ECU 23.

FIG. 2 shows the boost pressure control mechanism of the turbocharger in the first embodiment. In the figure, 31 indicates that turbocharging is in progress, 32 indicates a compressor of the turbocharger 31, and 33 indicates a turbine. An air flow meter 24 and an air cleaner 35 are located upstream of the compressor 32. A throttle valve 36 is provided downstream of the compressor 32, and an engine main body 37 is located downstream of the throttle valve 36. The turbine 33 is bypassed by a bypass passage 38, and a wastegate valve 39 is provided in the bypass passage 38.

The waste gate valve 39 is driven to open and close by an actuator 40. Actuator 40 includes a diaphragm 42 to which rod 41 is attached, and rod 41 is connected to wastegate valve 39 . The actuator 40 has chambers 43 and 44 partitioned by the diaphragm 42, and the chamber 43 is connected to the compressor 32 and the throttle valve 36.
The air intake passage 45a is connected to the air intake passage 45a. A spring 46 in the chamber 44 pushes the diaphragm 42 back toward the chamber 43.
The chamber 44 is connected to a vacuum switching valve (VSV) 47. The vacuum switching valve 47 is connected to an intake passage 45b between the throttle valve 36 and the engine body 37 via a vacuum tank 48. The vacuum switching valve 47 is driven by the output signal from the aforementioned EC1J23, and the wastegate valve 39 closes when atmospheric air is introduced into the chamber 44 of the actuator 40.
It is configured to open when negative pressure is introduced.

The procedure for controlling the boost pressure of the turbocharger described above is as follows:
It is programmed in the CPU 23a of the ECU 23. The same applies to the embodiments described later.

FIG. 3 shows a flow diagram of compression ratio switching and boost pressure control in the first embodiment.

As shown in the figure, first, the CP in the ECU 23 is
An interrupt is made to U23a, and in step 51 the engine speed NE and intake air amount Q are input as engine operating conditions, and in step 52 the compression ratio is determined. Figure 4 shows
It shows a compression ratio map, and as shown in the figure, the horizontal axis shows the engine speed NB, and the vertical axis shows the ratio Q/NE between the intake air IQ and the engine speed NE. It has a boundary value C that separates the region A and the low compression ratio region B. Therefore, in step 52, when the signals from the engine speed sensor 25 and the air flow meter 24 are input, depending on whether the intersection of the corresponding maps is in the high compression ratio region A or the low compression ratio region 8, It outputs an output indicating whether a high compression ratio or a low compression ratio should be used.

Once the compression ratio ε is determined in step 52, the process proceeds to step 53 where it is determined whether the determined compression ratio ε is a high compression ratio or a low compression ratio. If the higher compression ratio is selected in step 53, the process proceeds to step 54, where the actual compression ratio is detected, and if the result is a high compression ratio, the process proceeds to step 55 and returns. If the high compression ratio is not reached, the process proceeds to step 56, where the high compression ratio is achieved.

When the compression ratio is switched to a high compression ratio, the process proceeds to step 57 and supercharging is stopped. That is, an actuation signal is output from the ECU 23 to the vacuum switching valve 47, and negative pressure is introduced into the chamber 44 of the actuator 40. the result,
For example, the waste gate valve 39 is fully opened, exhaust gas is bypassed, and supercharging is stopped. Then, in step 58, the ignition timing is changed to a high compression ratio, and in step 59, the compression ratio flag is set to F=-1, and then the process returns to step 55.

Note that if the lower compression ratio is selected in step 53, the process proceeds to step 60 and the actual compression ratio is detected. As a result, if the compression ratio is not high, the process returns to step 55, and if the compression ratio is high, the process proceeds to step 61, where a low compression ratio is achieved.

When the compression ratio is switched to a low compression ratio, the process proceeds to step 62 and supercharging is started. That is, the signal from the ECU 23 is turned off, and the atmosphere is introduced into the chamber 44 of the actuator 40 by operating the vacuum switching valve 47. Therefore, the diaphragm 42 is pushed back by the spring 46, and the wastegate valve 39 connected via the rod 41 is closed. Therefore, exhaust gas bypass is stopped and supercharging is started. Next, the process proceeds to step 63, where the ignition timing is changed to a low compression ratio, and in step 64, the compression ratio flag is set to F=O, and the process returns to step 55.

In this way, when the compression ratio is switched to a high compression ratio,
The wastegate valve 39 is fully open or close to fully open, most of the exhaust gas is bypassed, and supercharging is stopped or significantly reduced. Therefore, during light loads with a small amount of intake air, the occurrence of non-king is suppressed, combustion efficiency is increased, and fuel consumption can be kept low.

Furthermore, when the compression ratio is switched to a low compression ratio, the waste gate valve 39 is completely closed, so exhaust gas is not bypassed and supercharging is started. In this case, a large amount of air is taken into the combustion chamber, but the compression ratio is low, so the occurrence of knocking is suppressed and high output can be obtained.

Furthermore, as shown in FIG. 5, when the compression ratio is high, the supercharging pressure P1 is significantly suppressed or stopped by the wastegate valve 39, so the value of the output torque T immediately before switching the compression ratio ε1 is Output torque T immediately after switching the ratio ε
It becomes possible to set almost the same value as 1, and when switching the compression ratio, a torque characteristic that changes smoothly can be obtained.

Second Embodiment FIG. 6 shows a supercharging control mechanism for a turbocharger of a turbocharged internal combustion engine equipped with a variable compression ratio device according to a second embodiment of the present invention. The second embodiment differs from the first embodiment in that it has a drive mechanism for the waste gate valve and a bypass passage on the compressor side. Therefore, parts that are similar to those in the first embodiment are designated by the same reference numerals as those in the first embodiment, and the explanation thereof will be omitted.
Only the different parts will be explained.

In this embodiment, the air flow meter 42 and the compressor 3
An intake passage 45C between the compressor 32 and the throttle valve 36 and an intake passage 45a between the compressor 32 and the throttle valve 36 are communicated through a bypass passage 71. A bypass valve 72 is provided in the bypass passage 71. Bypass valve 72 is connected to actuator 40 , and actuator 40
is driven by a vacuum switching valve 47. Vacuum switching valve 47 is connected to surge tank 73 downstream of throttle valve 36 via vacuum tank 48 .

The wastegate valve 39 includes an actuator 75 having a diaphragm 74 that has been commonly used in the past.
is connected to. A chamber 76 defined by the diaphragm 74 of the actuator 75 is connected to the intake passage 45a.

FIG. 7 shows a flow diagram of compression ratio switching and supercharging pressure control in the second embodiment.

As shown in the figure, first, the CP in the ECU 23 is
An interrupt is made to U23a, and in step 81, the engine speed NB is set as the engine operating condition.

The intake air amount Q is input, and in step 82 the compression ratio is determined from the map shown in FIG. That is, in step 82, the engine speed sensor 25 and the air flow meter 24
When the signal from It's about to come out.

Once the compression ratio ε is determined in step 82, the process proceeds to step 83 where it is determined whether the determined compression ratio ε is a high compression ratio or a low compression ratio. If the higher compression ratio is selected in step 83, the process proceeds to step 84 where the actual compression ratio is detected, and if the result is a high compression ratio, the process proceeds to step 85 and returns. If the high compression ratio is not reached, the process proceeds to step 86, where the high compression ratio is achieved.

When the compression ratio is switched to a high compression ratio, the process proceeds to step 87 and supercharging is stopped. That is, an actuation signal is output from the ECU 23 to the vacuum switching valve 47, and negative pressure is introduced into the chamber 44 of the actuator 40. the result,
For example, the bypass valve 72 is fully opened, intake air is bypassed, and supercharging is stopped. Then, in step 88, the ignition timing is changed to one for a high compression ratio, and in step 89, the compression ratio flag is set to F=1, and then the process returns to step 85.

Note that if the lower compression ratio is selected in step 83, the process proceeds to step 90 and the actual compression ratio is detected. As a result, if the compression ratio is not high, the process returns to step 85, and if the compression ratio is high, the process proceeds to step 91, where a high compression ratio is achieved.

When the compression ratio is switched to a low compression ratio, the process proceeds to step 92 and supercharging is started. That is, the signal from the ECU 23 is turned off, and the atmosphere is introduced into the chamber 44 of the actuator 40 by operating the vacuum switching valve 47. Therefore, the diaphragm 42 is pushed back by the spring 46, and the bypass valve 72 connected via the rod 41 is closed. Therefore, bypassing of intake air is stopped and supercharging is started. Next, in step 93, the ignition timing is changed to a low compression ratio, and in step 94, the compression ratio is set to F-0, and the process returns to step 85.

In this embodiment, since the intake air is bypassed, the turbine 33 and compressor 33 are already rotating when the bypass valve 72 is closed, so that a quick response can be obtained. Other operations are similar to those in the first embodiment.

〔Effect of the invention〕

As explained above, when using a turbocharged internal combustion engine equipped with the variable compression ratio device of the present invention, the electronic control device of the variable compression ratio device performs supercharging at low compression ratios and supercharging at high compression ratios. Since the control function is provided to stop or significantly reduce the engine output torque, drastic fluctuations in the engine output torque when switching the compression ratio can be prevented, and drivability can be greatly improved.

Furthermore, since the compression ratio is low when the load is high, high output can be obtained by sufficient supercharging while suppressing non-king. Since the compression ratio is high when the load is low, combustion efficiency is increased and fuel consumption can be kept low.

[Brief explanation of drawings]

FIG. 1 is a control system diagram of a turbocharged internal combustion engine equipped with a variable compression ratio device according to a first embodiment of the present invention, and FIG. 2 is a boost pressure control mechanism for a turbocharger according to a first embodiment of the present invention. FIG. 3 is a flow diagram of compression ratio switching and boost pressure control in FIG. 1, FIG. 4 is a compression ratio switching map diagram, and FIG. A relationship diagram showing the relationship between compression ratio, boost pressure, and output torque. FIG. 6 is a schematic diagram of a turbocharger pressure control mechanism according to the second embodiment of the present invention. FIG. 7 is a diagram showing the relationship between compression ratio, boost pressure, and output torque. A flow diagram of compression ratio switching and boost pressure control in the embodiment. Figure 8 shows the relationship between compression ratio, boost pressure, and output torque with respect to load changes when supercharging control according to the compression ratio is not performed. Figure, is. 3・・・・・・・・・・Koname Tattingrod 6・
・・・・・・・・・・・・Eccentric bearing 8・・・・・・
......Lock bin 10......Hydraulic passage for locking the lock bin 11......Hydraulic passage for unlocking the lock bin 22... .........Switching valve 23...ECLJ (electronic control unit) 23a...CPU 24......・・・Air flow meter 25・
...... Engine speed sensor 27...
・・・・・・・・・Igniter (ignition control ■circuit) 2
8・・・・・・・・・・・・Distributor 29・
・・・・・・・・・・・・Spark plug 30・・・・・・
・・・・・・Knock sensor 31・・・・・・・・・・
...Turbocharger 38...Bypass passage 39...Wastegate valve 40...Actuator 47 .........Vacuum switching pulp 71......Bypass passage 72
......Bypass valve NE...
...Engine speed Q...Intake air type license application Person Toyota Motor Corporation Figure 3 Figure 4 Ratio of engine/revolutions to HE number Figure 5 Throttle 1 degree (negative 6゛i) Fig. 7 Fig. 8 Throttle opening degree (load)

Claims (1)

[Claims] (1) A turbocharged internal combustion engine is equipped with a variable compression ratio device, and the electronic control device of the variable compression ratio device performs supercharging at low compression ratios and stops or significantly reduces supercharging at high compression ratios. An internal combustion engine with a turbocharger equipped with a variable compression ratio device characterized by having a control function to control the compression ratio.