JPS6260935A - Mechanical supercharge engine with variable compression ratio device - Google Patents

Abstract

PURPOSE:To prevent knocking at the time of switching a supercharger or altering the compression ratio by giving a different compression ratio at the time of supercharging a mechanically supercharged engine from the time with no supercharging, and by sinking the compression ratio before turning on the supercharger. CONSTITUTION:In an engine equipped with a mechanical supercharger 3 and a compression ratio varying device 10, a control computer 13 inputs signals from a revolving speed sensor 14 and a suction air amount sensor 15, and when the load is over a specified value, the supercharger 3 is driven, and the compression ratio is sunk by said compression ratio varying device 10. At this time, the compression ratio shall be sunk before the supercharger 3 is turned on. This will prevent knocking at the time of switching the supercharger.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a supercharger and compression ratio control structure for a mechanical supercharged engine equipped with a variable compression ratio device.

[Conventional technology] Engine supercharging is achieved by using a turbo supercharger that uses heat from exhaust gas, or by using a mechanical supercharger that mechanically links the rotation of the crank and the rotation of the supercharger. There is.

In a mechanically supercharged engine, output is required on the high load side, so the supercharger is connected to the crank only when the load is high, and is turned freely when the load is light or medium. In a mechanically supercharged engine, the amount and pressure of engine intake air increases during supercharging, which tends to cause knocking, so it is necessary to set the compression ratio low to prevent knocking (Japanese Patent Application Laid-Open No. 1973-1999). 106724@publication,
(Japanese Patent Application Laid-open No. 165541/1983).

[Problems to be Solved by the Invention] For this reason, even at light loads without supercharging, the compression ratio is set low from the beginning, resulting in poor fuel efficiency during medium and light loads. In addition, this compression ratio is selected under the conditions that produce the highest amount of supercharging in order to prevent abnormal combustion such as knocking and plave, so there is a problem that the output will deteriorate under conditions other than these even during supercharging. Ta. Further, even if the compression ratio can be lowered during supercharging compared to when no supercharging is performed, if the compression ratio is lowered after the supercharger is turned on, there is a risk that knocking will occur.

In a mechanical supercharged engine, the present invention changes the compression ratio between supercharging and non-supercharging, and also maintains a low compression ratio during supercharging and changes the compression ratio when switching the supercharger on and off. The purpose is to prevent knocking from occurring when making changes.

[Means for Solving the Problems] A mechanical supercharged engine with a variable compression ratio device of the present invention in accordance with the above object includes a mechanical supercharged engine equipped with a variable compression ratio device, and a control computer for the variable compression ratio device. It also has a control function that lowers the compression ratio when the supercharger is on compared to when it is off, and also lowers the compression ratio before the supercharger is turned on.

[Function] In the above-mentioned mechanical supercharged engine with variable compression ratio device,
When the load is high, the supercharger is turned on to increase output and the compression ratio is lowered to prevent knocking. Furthermore, while supercharging is not required, when the load is light, the supercharger is turned off, resulting in no supercharging, and the compression ratio is increased to improve fuel efficiency.

Also, by lowering the compression ratio before turning on the supercharger,
There is no possibility of knocking occurring when switching the supercharger on and off or when changing the compression ratio.

[Embodiment] Hereinafter, a preferred embodiment of a mechanical supercharged engine with a variable compression ratio device according to the present invention will be described with reference to the drawings.

First Embodiment FIG. 1 shows a system of an apparatus according to an embodiment of the present invention. In the figure, a mechanical supercharger 3 is installed in the intake passage 2 of an engine 1 (the figure shows a gasoline engine, but a diesel engine may also be used), which is linked to the rotation of a crank 4. and is rotated via a belt 5.

A bypass passage 6 is provided in the intake passage 2 so as to bypass the supercharger 3, and a bypass valve 7 for turning the bypass passage 6 on and off is provided in the bypass passage 6. The bypass valve 7 is turned on and off by a vacuum switching valve 8 (VSV).

On the engine, a variable compression ratio device 1 is installed facing the combustion chamber 9.
o is provided. The compression ratio variable device 10 is composed of, for example, a variable volume piston 11 that is driven stepwise by a servo motor 12.

The variable compression ratio device 10 is driven by a control computer 13. The control computer 13 receives input signals from a rotational speed sensor 14 that detects the engine rotational speed, and an intake air amount sensor 15 that is provided in the intake passage 2 and includes an air flow meter that detects the amount of intake air. The output of the control computer 13 is sent to the variable compression ratio device 10 and also to the supercharger 3 and VSV 8 to control supercharging.

In addition, in Fig. 1, 16 is a throttle valve;
7 is a surge tank, 18 is an air cleaner, 19 is an intake valve, 20 is an engine piston, and parts 16~]
Reference numeral 9 consists of a member having the same structure as the conventional one.

FIG. 2 shows the configuration of the control computer 13 in a flowchart.

Operation of the computer 13 starts at block 21,
In block 22, the load (Q/N> is calculated from the intake air amount Q based on the signal from the intake air amount sensor 5 and the engine rotation iN based on the signal from the rotation speed sensor 14.Next, in block 23, The load (Q/N) is stored in advance in the control computer 13, and it is determined whether the load (Q/N>S) at which the engine requires an output is determined (Q/N).
If N) is equal to or greater than (Q/N)s, the flag f is initially set to O, so the process passes through block 24 and reaches block 25. In block 25, the motor 12 is driven to reduce the compression ratio of the engine from ηO to η2, and in block 26 it is confirmed whether the compression ratio has definitely decreased to η2. Next, proceed to block 27 and supercharge 1 (
Turn on S/C:)3 and switch vsvs. As a result, supercharging of the engine 1 is started. and,
Block 28 sets the flag f, i.e. f=1
Then, the process reaches block 29, and the first routine ends. After a predetermined period of time, which is sufficiently short compared to the change in engine operating conditions, the routine is restarted from block 21.

If (Q/N) is still larger than <Q/N> s in block 23, it means that supercharging is in progress, so in block 30 the load (Q/N) is
/N), and calculates a predetermined compression ratio η according to block 31
The motor 12 is controlled so that the compression ratio η is obtained. (
If Q/N> is smaller than (Q/N)S, that is, light,
For medium loads, output is not required, so
In block 32, the supercharger 3 is turned off, and in block 33, the flag f is set to O, and in block 34, the compression η is set to η.
○ to improve fuel efficiency.

In FIG. 2, block diagram A shows an example of the relationship between the load (Q/N> and the compression ratio η in block 30, and it is determined that the larger (Q/N) is, the lower the compression ratio η is. Further, block diagram B shows the relationship between the load (Q/N> and on/off of the supercharger 3, and shows an example of control characteristics in block 23.

Next, the operation of the mechanical supercharged engine with a variable compression ratio device configured as described above will be explained.

1 control computer 13 operates at predetermined time intervals to
Perform the routine shown.

First, in block 23, it is determined whether the load is high, medium, or light, and if the load is high, the compression ratio is set to ηO in block diagram A.
The compression ratio is changed to η1 from /N
> Calculate the compression ratio η according to
2, it is controlled to η. After this compression ratio change, supercharging is started and knocking is prevented from occurring.

On the other hand, in the case of medium or light loads, no supercharging is performed in block 31 and the compression ratio is set to high compression ratio ηO in block 33 to improve fuel efficiency.

Compression ratio change (Means for turning on the supercharger for barley include a type in which the computer 13 detects the end of the motor 12 drive signal and turns on the supercharger, as in the Komi case, as well as a timer to change the compression ratio. The same effect as in the Kinotsu case can be obtained even in the case of a type in which the supercharger is turned on after setting a constant light time delay.

Second Embodiment FIGS. 3 and 4 show a second embodiment of the present invention. In the second embodiment, the parts that are similar to the first embodiment include the first
The same reference numerals as those in the embodiment are given, and the explanation thereof will be omitted, and different parts will be explained.

Second. In the embodiment, similarly to the variable compression ratio device 1o, the fuel injection pipe 40 also has its fuel injection (2) controlled by the $ control computer 13.

In Figure 4,! The flowchart shows the configuration of the computer 13.

The operation of the computer 13 starts at block 21,
In block 22, load (Q/N> is calculated, and if (Q/N> is greater than or equal to (Q/N>s), block 24 is passed to block 25, where the compression ratio is reduced from ηO to η2. On the other hand, at the same time as block 25 is reached, information is also transmitted to block 41, and the fuel is injected by △Gf more than the injection ■f <af> for the normal load (Q/N>, thereby eliminating the output drop.Subsequently, From block 25 and block 4, proceed to block 27 via block 26, and proceed to supercharging v1 (
Supercharging of the engine 1 is started by turning on S/N>3 and switching VSV8.

(When Q/N> is smaller than (Q/N>S, that is, when the load is light or medium, no output is required. Therefore, the supercharger 3 is turned off in block 32, and the supercharger 3 is turned off in block 33. The flag f is set to ○, the injection port is returned to normal f (Gf) in block 42, and the compression ratio η is set to ηO in block 34.
and improve fuel efficiency.

In the apparatus of this embodiment, since the injection amount is increased according to the load, a decrease in output due to a decrease in the compression ratio can be avoided. Therefore, after reducing the compression ratio, the supercharger (S
Even if /C>3 is turned on, the output will no longer change suddenly, and the torque difference will become smaller, resulting in less shock.

[Effects of the Invention] When using a mechanical supercharged engine with a variable compression ratio device of the present invention, the compression ratio is changed between supercharging and non-supercharging, and the non-supercharging compression ratio is changed. In addition to improving fuel efficiency by increasing the pressure, when supercharging, it is necessary to lower the compression ratio before turning on and off the turbocharger, so when switching the turbocharger or changing the compression ratio. It is possible to prevent knocking and improve output.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a variable compression ratio mechanical passage-fed engine according to an embodiment of the present invention, FIG. 2 is a flow diagram of the functions of the control computer in the device shown in FIG. 1, and FIG. FIG. 4 is a system diagram of a mechanical supercharged engine with a variable compression ratio device according to a second embodiment of the present invention; FIG. 4 is a flow diagram of the functions of the control computer in the device of FIG. 3; 1・・・・・・・・・・・・・・・・・・・・・・・・
Engine 3・・・・・・・・・・・・・・・・・・
・・・・Supercharger 10・・・・・・・・・・・・・・・・
...Compression ratio variable device 13...
・・・・・・・・・Control wholesale computer Q/N・・・・
・・・・・・・・・・・・Load △Gf・・・・・・
・・・・・・・・・・・・Increase in fuel (1 other person)

Claims (2)

[Claims] (1) A mechanical supercharged engine is equipped with a variable compression ratio device,
A variable compression ratio characterized in that the control computer of the variable compression ratio device is provided with a control function to lower the compression ratio when the supercharger is on than when it is off and to lower the compression ratio before the supercharger is turned on. Mechanical supercharged engine with equipment. (2) The mechanical supercharged engine with a variable compression ratio device according to claim 1, wherein the control computer has a control function to increase and inject fuel at the same time as the compression ratio decreases.