JPS6278440A - Mechanical supercharged engine with variable compression ratio device - Google Patents

Abstract

PURPOSE:To prevent acceleration response from becoming worse by making compression ratio for a supercharger set at On lower than that set at OFF, and if knocking tends to occur at time of shifting from OFF to ON, setting the supercharger at ON after the compression ratio has been reduced. CONSTITUTION:The above mentioned engine is provided with a mechanical supercharger 3 continuously rotated through an engine 1 and a belt 5 in its suction path 2, and a bypass path 6 provided with a bypass valve 7 is formed around the supercharger 3, and in addition, a variable compression ratio device 10 is mounted facing on a combustion chamber 9. In case of controlling the above engine by a control computer 13, the engine is first judged of its operating under which of heavy, half and light loads, and then the supercharger 3 is set at ON in the case of the heavy load. In this case, if knocking caused by the temperature of suction or water tends to occur, the supercharger 3 is set at ON after the engine 1 has been given a low compression ratio by the variable compression ratio device 10. On the other hand, in the case of the half or light load, the supercharger 3 is set at OFF, and the engine 1 is controlled to increase its compression ratio.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides variable compression ratio control for the supercharger and compression ratio of mechanically supercharged engines. U'g'ru.

[Conventional technology] Engine supercharging is achieved by using a turbo supercharger that uses the heat of lost air, 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, knocking is likely to occur because the engine intake air amount and pressure increase during supercharging, so the compression ratio is set low to prevent knocking (Japanese Patent Application Laid-Open No. 106724 @ Public notice,
(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. Therefore, it is desirable to switch the compression ratio between supercharging and non-supercharging. When changing the compression ratio between supercharging and non-supercharging, there is a risk that the compression ratio will be delayed and knocking will occur the moment the transition from non-supercharging to supercharging occurs. For this reason, it is conceivable to adopt a system in which the compression ratio is first lowered and then supercharging is performed. However, in this case, a non-supercharging state occasionally occurs due to a decrease in the compression ratio, and since supercharging is delayed in response to depression of the accelerator, the problem often arises that the acceleration response deteriorates.

In a mechanically supercharged engine, the present invention changes the compression ratio between supercharging and non-supercharging, and maintains a low compression ratio during supercharging, and also reduces transients when transitioning from non-supercharging to supercharging. The objective is to achieve both the occurrence of knocking and the prevention of deterioration of acceleration response.

[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. In addition, when the turbocharger is on, the compression ratio is lowered than when it is off, and in an atmosphere where knocking is likely to occur when switching from off to on, the control function lowers the compression ratio and then turns on the supercharger. It is made up of things that have lasted.

[Function] In the above mechanical supercharged engine with variable compression ratio device,
When the load is high (11.1), the output is increased by turning on supercharging, 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.

In addition, when switching the turbocharger from off to on, the load is first determined, and if the load is high, it is also determined whether the atmosphere is likely to cause knock due to the intake temperature, etc., and if the intake temperature is high, in other words, the knock If this is unlikely to occur, first reduce the compression ratio and then turn on the supercharger after a predetermined period of time to prevent knocking during transient times.

On the other hand, if the intake air temperature is low, that is, when knocking is unlikely to occur, the intake air temperature will not rise immediately even after supercharging, so knocking will not occur even if the compression ratio is high for a while. Therefore, by first turning on the supercharger and then lowering the compression ratio, it is possible to prevent deterioration in acceleration response.

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

FIG. 1 shows a system of an apparatus according to an embodiment of the present invention. In the figure, a mechanical supercharger 3 is provided in the intake passage 2 of an engine 1 (the figure shows a gasoline engine, but a diesel engine may also be used), and the mechanical supercharger 3 is connected 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).

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

The drive of the variable compression ratio device 10 is controlled by a control computer 13. The control computer 13 includes a rotation speed sensor 14 that detects the engine rotation speed, and an intake passage 2.
A signal is input from an intake air amount sensor 15, which is provided with an air flow meter or the like installed at C and 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 superchargers 3 and VSVA 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 screw 1~, parts 16~
Reference numeral 20 is 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 10 according to the signal from the intake air amount sensor 15 and the engine rotation speed N according to the signal from the rotation speed sensor 14.Subsequently, in block 22, The load (Q/N> is stored in advance in the computer 13, and it is determined whether the engine requires an output load, (Q/N)s or not. (Q/N)
> is (Q/N)s or more, that is, when the load is high,
At block 23, it is determined whether the intake air temperature, water temperature, etc., are greater than or less than the preset intake air temperature, water temperature, etc.
The compression ratio η is first set to a low compression ratio η1, and then the process is reached to block 25, where it is determined whether the elapsed time 11 after switching the compression ratio η to η1 is greater than a predetermined time ts1, and the predetermined time is If ts1 has elapsed, it reaches block 26 and turns on the supercharger (3); if it has not elapsed, then it goes to block 27 without turning on the supercharger 3 and ENDs to repeat the routine.Also, block 23 Intake temperature, water temperature, etc.
is lower than the predetermined temperature Ts, that is, when knocking is difficult to occur, the process proceeds to block 28, where the supercharger 3 is first turned on, and then the process proceeds to block 29, where the supercharger 3 is turned on. It is determined whether or not the elapsed time 12 is longer than a predetermined time tS2, and if the predetermined time ts2 has elapsed, the process proceeds to block 30 and the compression ratio η is switched to the low compression ratio η1. If T2 is smaller than ts2 in block 29, the process directly advances to block 27 and repeats the ENDL routine.

If (Q/N") is smaller than (Q/N)S in block 22, that is, in the case of light or medium load, no output is required, so the supercharger 3 is turned off in block 31. At the same time, in block 32, the compression η is increased to a high compression ratio ηO to improve fuel efficiency.

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

The computer 13 operates at predetermined time intervals to perform the routine shown in FIG.

First, in block 22, it is determined whether the load is high, medium, or light, and if the load is high, supercharging is applied. however,
When switching the turbocharger 3 from oat to on, block 23 judges whether or not the atmosphere is likely to cause knocking. If the atmosphere is such that knocking is likely to occur, the process proceeds to block 24, where the compression ratio is first set to a low level and the engine is turned on for a certain period of time. After the elapse of time, the supercharger 3 is turned on, and if the atmosphere is such that knocking is difficult to occur, the process proceeds to block 28, where the supercharger 3 is first turned on, and after a certain period of time has elapsed, the compression ratio is switched to a low compression ratio.

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. In addition, in an atmosphere where knocking is unlikely to occur,
Turning on the supercharger 3 and switching to the low compression ratio may be performed at the same time.

[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. By increasing the fuel consumption, fuel efficiency can be improved, and by lowering the compression ratio during supercharging, knocking can be prevented and output can be improved.

Furthermore, when switching supercharging from off to on, if the atmosphere is such that knocking is likely to occur, the compression ratio is first set to a low one, and then supercharging is turned on, which reliably prevents knocking from occurring. When the atmosphere is difficult, the turbocharger is turned on at the same time or first, and the compression ratio is then reduced to a low compression ratio, improving acceleration response, thereby preventing the occurrence of knock and improving acceleration response. .

[Brief explanation of drawings]

FIG. 1 is a system diagram of a mechanical supercharged engine with a variable compression ratio device according to an embodiment of the present invention, and FIG. 2 is a flow diagram of the functions of a control computer in the device of FIG. 1.

Claims (1)

[Claims] (1) A mechanical supercharged engine is equipped with a variable compression ratio device,
The control computer of the variable compression ratio device is programmed to lower the compression ratio when the turbocharger is on than when it is off, and to reduce the compression ratio before supercharging in an atmosphere where knocking is likely to occur when switching from off to on. A mechanical supercharged engine with a variable compression ratio device, which is characterized by having a control function to turn on the engine.