JPS6270633A - Mechanical supercharge engine with variable compression ratio device - Google Patents

Abstract

PURPOSE:To reduce fuel consumption and improve an output, by a method wherein a varying compression ratio device is mounted to a mechanical super charge engine, during operation of a supercharger, a compression ratio is re duced over that prevailing during inoperative state, and a compression ratio is changed depending upon the presence of the occurrence of knocking. CONSTITUTION:A mechanical supercharger 3 rotated in linkage with a crank 4 is mounted in a suction passage 2 through a belt 5, and a bypass passage 6, which runs around the supercharger 3 and in which a bypass valve 7 is located, is provided. Meanwhile, a compression ratio varying device 10 is placed in an engine 1 in a manner to face on a combustion chamber 9, and is so constituted as to drive a piston 11 for varying volume with the aid of a servo motor 12. When the compression ratio varying device 10 is controlled by a control computer 13, a servo motor 12 is controlled so that the supercharger 3 is turned ON when an engine load is increased to higher than a given value, and a compressed pressure is reduced in a state in that the bypass valve 7 is closed. Thereafter, a compression ratio is varied depending upon the presence of the occurrence of knocking.

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 exhaust heat, and by using a mechanical supercharger that mechanically links the rotation of the crank and the rotation of the supercharger. There is something.

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 amount and pressure of the engine intake air increases during supercharging, so the compression ratio is set low to prevent knocking (Japanese Patent Laid-Open No. 106724/1986). No. Publication,
(Japanese Patent Application Laid-open No. 165541/1983).

[Problems to be Solved by the Invention] For this reason, at light loads without supercharging: (b) Since the compression ratio is set low from the beginning, fuel efficiency at medium and light loads deteriorates. In addition, even during supercharging under high load, the amount of supercharging changes depending on the engine operating conditions, so the compression ratio must be selected based on the conditions with the largest amount of supercharging, so the output during supercharging The problem is that it also gets worse. For example, even if the compression ratio is continuously changed according to the load (Q/N) value, if the compression ratio is determined regardless of the presence or absence of knock, it is necessary to It is necessary to set the compression ratio low with some margin in consideration of variations in the engine speed, etc., and this may result in a loss in terms of output and fuel efficiency.

In a mechanical supercharged engine, the present invention changes the compression ratio between supercharging and non-supercharging, and maintains a low compression ratio during supercharging, and uses the knocking control function of the control computer after supercharging is turned on. The purpose is to optimally change the compression ratio.

[Means for Solving the Problems] A mechanical supercharged engine with a variable compression ratio device of the present invention in accordance with this object includes a variable compression ratio device provided in the mechanical supercharged engine, and a control computer for the variable compression ratio device. In addition, it has a knocking control function that lowers the compression ratio when the supercharger is on compared to when it is off, and then changes the compression ratio depending on whether or not knocking occurs and/or as the ignition timing retard width increases. Become.

[Function] In the above-mentioned mechanical supercharged engine with variable compression ratio device,
When the load is high, supercharging 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.

In addition, during supercharging, the compression ratio can be optimally controlled by changing the compression ratio depending on the presence or absence of knocking and/or the width of the ignition timing retardation, further improving output and preventing deterioration of fuel efficiency. It can be measured.

[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.

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 Ganlin engine, but a diesel engine may also be used), and is linked to the rotation of a crank 4. The belt 5 is rotated by the 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 (VS).

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

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.
In addition to inputting a signal from an intake air amount sensor 15, which is provided in the engine 1 and includes an air flow meter or the like, and which detects the amount of intake air, a signal from a knock sensor 18, which is installed in the engine 1, and which detects the presence or absence of knocking is inputted. The output of the control computer 13 is sent to the variable compression ratio device 1o and also to the supercharger 3 and vsva to control supercharging.

In addition, in FIG. 1, 16 is a slot valve, 17
19 is a fuel tank, 19 is an intake valve, 20 is an engine piston, and parts 16, 17, 19, and 20 are made of members having the same structure as conventional ones.

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, negative 7i? i(Q/N> is calculated by h1. Next, in block 23, the load (Q/'N
) is stored in the computer 13 in advance, and it is determined whether the load (Q/N)s is such that the engine requires an output. If (Q/N) is greater than or equal to (Q/N)S, the flag f is initially set to OG, : so block 2
4 and reaches block 25, supercharger (S/C) 3
is turned on, and the vsvs is switched so that the bypass valve 7 is closed. As a result, supercharging of the engine 1 is started. Next, the process proceeds to block 26, where the flag r is set, that is, f=1, and the process proceeds to block 27. In block 27, the motor 12 is driven to reduce the compression ratio of the engine 1 from ηO to η1 to prevent knocking. Then, the process reaches block 28, 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. In block 23 (Q/N
> is still greater than (Q/N)S, block 24
At block 35, the control computer 13 determines the presence or absence of knocking based on the signal from the knock sensor]8, and at block 36 or block 37, the compression ratio η is changed up or down by Δη.

When (Q/N) is smaller than (Q/N)s, that is, when the load is light or medium, no output is required, so the supercharger 3 is turned off in block 31 and the In block 32, the flag f is set to O, and in block 33, the compression η is increased to ηO 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 27. 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.

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

First, in block 23, it is determined whether the load is high, medium, or light, and if the load is high, supercharging is applied, the compression ratio is changed from ηO to η1 in block diagram A, and the compression ratio is switched to a low compression ratio. For each routine, the presence or absence of knocking is determined in block 35. If there is no knocking, the compression ratio η is increased by Δη in block 36, and if there is knocking, the compression ratio η is increased by Δη.
7, the compression ratio η is lowered by Δη to control knocking.

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.

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.

In the second embodiment, the compression ratio η is changed by the control computer 13 in accordance with the ignition timing retard width θK.

FIG. 4 shows the configuration of the control computer 13 in a flow chart.

If supercharging continues, block 40 determines whether the ignition timing retard width θK, which controls knocking, is larger or smaller than a predetermined value a, and if it is larger, block 41 changes the compression ratio to the current compression ratio. It is lowered by b than ηi. If the ignition timing retard width θK is smaller than the predetermined value, the process advances to block 42 as shown in block diagram C, and it is determined at lυ whether 0K=O, and θ
If K is not O, the process ends. If θ = O, it is determined in block 43 whether the compression ratio ηi at that time is η1,
If ηi=η1, the process ends; if ηi=η1, the compression ratio is increased by b from ηi in block 44.

In such an embodiment device, it is determined whether the compression ratio is optimal by detecting whether the ignition timing retard width θK, which controls knocking, is larger or smaller than a predetermined value a, and the engine 1
Improves fuel efficiency and output by adjusting the compression ratio to the optimum compression ratio that changes depending on the operating conditions.

[Effects of the Invention] The mechanical supercharged engine with variable compression ratio device of the present invention changes the compression ratio between supercharging and non-supercharging in a mechanical supercharged engine, thereby reducing the non-supercharging compression ratio. Increasing the fuel consumption can improve fuel efficiency, and during supercharging, by changing the compression ratio depending on whether knocking occurs and/or the width of ignition timing retardation, knocking can be prevented and output can be improved. be able to.

[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; 3 is a system diagram of a mechanical supercharged engine with a variable compression ratio device according to a second embodiment of the present invention, and FIG. 4 is a flow diagram of the functions of the control computer in the device of FIG. 3.

Claims (2)

[Claims] (1) A mechanical supercharged engine is equipped with a variable compression ratio device,
The control computer of the variable compression ratio device is characterized by having a knocking control function that lowers the compression ratio when the supercharger is on compared to when it is off and then changes the pressure claw ratio depending on whether or not knocking occurs. Mechanical supercharged engine with variable compression ratio device. (2) The mechanical supercharged engine with a variable compression ratio device according to claim 1, wherein the control computer has a knocking control function that changes the compression ratio according to the ignition timing retard width.