JPS5946370A - Compression ratio variable type internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent knocking due to the delay of control on the lowering of compression ratios by using a system in which when acceleration is made by quickly opening a throttle valve, angular velocity retardation control is made during the ignition period in an interlocking manner with the acceleration in an internal combustion engine in which reciprocal movement is made by an oil pressure according to load of the engine for a subpiston inside a subcylinder. CONSTITUTION:An ignition time control circuit 31 has a function by which angular velocity retardation control is made for a proper period of time by a proper angle in the angular velocity retardation direction on the basis of output signals from a throttle valve opening speed detection circuit 32 with respect to ignition time. When the opening speed of the throttle valve 9 exceeds apreset value by the step-in operation of accel pedal, since the ignition time is properly subjected to an angular velocity retardation control in the direction of angular velocity retardation only for a proper period of time, the occurrence of knocking due to the delay of retraction of subpiston 13 in the early period of the acceleration of engine is suppressed, and at a time when the subpiston 13 goes back to a given position beyond a proper period of time from the acceleration of the engine, the angular velocity retardation control of the ignition time is released.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable compression ratio internal combustion engine in which the compression ratio is changed in accordance with the load of the engine.

In an internal combustion engine, increasing the compression ratio can improve output and reduce fuel consumption, but increasing the compression ratio causes knocking in high load ranges.

For this reason, in a conventional internal combustion engine with a constant compression ratio, the compression ratio must be set to a value that does not cause knocking in the high load range, so it is not possible to produce sufficient output at t6 in the low load range, and it also reduces fuel consumption. cannot be reduced sufficiently.

Therefore, Japanese Patent Application Laid-Open No. 56-88926 as a prior art proposes a system in which a sub-piston inserted into a sub-cylinder communicating with a combustion chamber is moved back and forth by supplying and discharging hydraulic pressure at a certain load range of the engine. , the present inventors proposed making the compression variable, and in the earlier patent application (Japanese Patent Application No. 57'-48295-Yu), the present inventors proposed a method to make the compression variable. It was proposed that the compression ratio j-Jljli be made variable in stages by moving the sub-piston rearward by hydraulic pressure in proportion to the engine load.

However, when the auxiliary piston in the auxiliary cylinder is moved back and forth by hydraulic pressure in accordance with the engine load, due to the flow of hydraulic pressure or the restriction resistance of each port, the amount of intake air changes due to the engine load. In Lucara, there is inevitably a response delay in the longitudinal movement of the sub-piston, and when accelerating by rapidly opening the throttle valve in the intake passage to the engine, the compression ratio is low as the amount of intake air increases. Due to this delay in controlling the compression ratio to low during acceleration, knocking occurs frequently at the beginning of acceleration, which not only reduces output but also reduces drivability. It is.

The present invention provides a secondary piston in the secondary cylinder as described above,
In engines that move backward by oil pressure according to the engine load, when the throttle valve is suddenly opened to accelerate, the ignition timing is retarded in conjunction with this to prevent knocking due to a delay in controlling the compression ratio to a low level. The second invention detects the presence or absence of knocking during acceleration by rapidly opening the throttle valve, and retards the ignition timing accordingly when knocking occurs. It is something.

The present invention will be explained below with reference to drawings of embodiments. In the drawings, (1) is a cylinder block, (2) is a cylinder head m (3) is a screw that reciprocates within the cylinder bore (4) of the cylinder block (1)!・N, (5) is 13i
Each of the combustion chambers formed by recessing the lower surface of the cylinder head (2) is shown, and the combustion chamber (5) has an ignition plug (6) screwed onto the cylinder head (2) located approximately in the center thereof. At the same time, an intake port (8) with an intake valve (7)' and an exhaust port (not shown) with an exhaust valve are opened, respectively, and the intake port (8) is provided with a throttle valve (9) that is opened and closed by an accelerator pedal (not shown). intake passage acb
is connected.

0υ is an auxiliary cylinder bored in the cylinder head (2), and the auxiliary cylinder (1) has its lower side opened into the combustion chamber (5) and its upper side opened into the upper chamber of the cylinder head on the upper surface of the cylinder head (2). A cover plate Q2 is provided at the opening 4 of the sub-cylinder (11) to the upper chamber of the cylinder head to close this J-L.

(13 is an auxiliary piston 11f (slidably inserted into the auxiliary cylinder OD, and the outer periphery of the auxiliary piston 03 is equipped with a piston ring 04), and this auxiliary piston 0.11 is installed in the combustion chamber (5). As the secondary piston moves forward in the direction, the volume of the combustion chamber decreases and the compression ratio increases, and as the secondary piston moves back away from the combustion chamber (5), the ?7-bond of the combustion chamber increases and the compression ratio increases. It is designed to be lower, and this sub piston 0
■ is urged in the backward direction by spring 00, and the sub piston (1
On the back surface of (the surface on the back side of the combustion chamber (5)) there is a stem 0 (which extends in the axial direction from the center of the secondary piston 0).
9 is integrally provided, and the stem (IQ) is slidably penetrated through the cover plate θ and protrudes outward, while a hydraulic chamber ( A check valve (la
Port with l (5++ continuously via 1 [phase]).

Further, the stem (10 is provided with a passage (a) connected to the hydraulic chamber α force, and the portion where the stem θQ protrudes outward from the cover plate ()) is provided with a passage (a) connected to the hydraulic chamber α force. Spill port Ql for draining hydraulic oil into the upper chamber of the cylinder head
) is drilled.

(A) shows a spill ring which is one embodiment of the spill body, and the spill ring (A) is slidably fitted onto the stem 0, and the spill ring (A) is inserted into the combustion chamber. (5
The spill ring (A) closes the spill port 12) when the spill ring (A) moves forward in the direction of ), and the spill port CD opens when the spill ring (A) moves backward in the direction away from the combustion chamber. In addition, ~(A) is a lever provided in the upper chamber of the cylinder head with its midway part pivotally attached to the shaft (C), and one end of the lever (C) is connected to the spill ring (A). On the other hand, the other end is connected to a diaphragm mechanism (a) which is one embodiment of an actuator. This diaphragm mechanism (c) has a built-in diaphragm (a) connected to the other end of the lever (a) via a rod (c), and a diaphragm chamber (to) divided by the diaphragm (c). Push the other end of the lever (C) downward in the figure (7F direction, that is, provide a biasing spring (E) in the direction of sliding the spill ring (A) backwards), and press the other end of the lever (C) downward in the figure. c) Negative pressure passage (to)
1) Throttle valve divided into 1 intake passage 00 through
9) Connected to the downstream side of the intake negative pressure guisephram chamber (
By introducing (c), when the intake negative pressure increases toward vacuum as the engine load decreases, the spill link (a) is configured to slide 1111 times in proportion to this.

0υ is an ignition timing control circuit that controls the ignition timing at the spark plug (6) according to the load and rotation speed of the engine, and the ignition timing control circuit (3]) controls the ignition timing of the spark plug (6) according to the load and rotation speed of the engine. Opening speed detection circuit (has a function to retard the ignition timing by an appropriate angle and time in the retard direction from the ignition timing determined by the load and rotation speed based on the output signal jj from () s1) !I Throttle valve opening speed detection circuit (
The system calculates the speed in the opening direction of the throttle valve (9) by detecting the opening angle of the throttle valve (9) every unit time using a rotary potentiometer (g) on the throttle valve (9). When this opening speed exceeds a preset speed, it is determined that the engine is accelerating, and an output signal for ignition timing retard control is output to the ignition timing side (yg circuit 0υ).

In this configuration, when the spill ring (a) is moved in the forward direction from the position shown by the solid line to the position shown by the two-dot chain line in Fig. The flow of water stops and the check valve (1, 8
) The pressure in the hydraulic chamber αη to which hydraulic oil is constantly supplied from the boat 0 increases, so the auxiliary piston 0 moves forward toward the combustion chamber (5), and this 1) oil advance causes the spill port Qυ to move forward. When you advance to the opening, Spielbo 1- (
Hydraulic oil starts to flow out from the hydraulic chamber (
When the supply amount to 17J is balanced, the advance of the sub piston θno stops. Furthermore, when the spill ring (A) is moved in the backward direction from the position indicated by the two-dot chain line to the position indicated by the solid line, the spill port (A) is fully opened, the amount of flow from the spill port increases, and the pressure in the hydraulic chamber a decreases. Therefore, the secondary piston α■ retreats as if separated from the combustion chamber by the pressure of the combustion chamber (5) and/or the spring 0, and when this retreat progresses to the point where the spill port ■υ closes at the spill link Q2, When the flow rate from the spill port Qυ decreases and the flow rate balances with the supply meter, the sub piston o3
By moving the spill ring @, the position of the secondary piston 0 can be changed arbitrarily, and the compression ratio can be changed arbitrarily.In this case, the spill ring (2) When the intake negative pressure gradually increases toward vacuum as the engine load decreases, the spill link (2) As the engine load advances, the compression ratio (Q) gradually increases as the engine load decreases, and as the engine load increases and the intake pressure decreases toward atmospheric pressure, the spill ring (A) retreats. , the compression ratio gradually decreases as the load increases by 7 Mm, so that compression can be automatically and steplessly controlled in accordance with the engine load.

In this case, the actuator for operating the spill ring (A) is not limited to the Guyafram type actuator, but other types of actuators such as electric type may also be used. It is also possible to automatically control the compression ratio so that it decreases as the load increases and increases as the rotational speed increases.

When accelerating by opening the throttle valve (9) by depressing the accelerator pedal 7, the intake negative pressure decreases toward atmospheric pressure (1), which causes spilling (a).
When the secondary piston 0 moves back and the hydraulic oil in the hydraulic chamber 07) flows out from the spill port aυ,
Due to the outflow resistance of the hydraulic oil, the backward movement of the secondary piston θ■ tends to be delayed compared to the decrease in intake negative pressure.In this case, when the throttle valve opening speed is slow, the backward movement delay of the secondary piston 03 hardly becomes a problem. If the opening speed of the throttle valve (9) is fast, knocking will occur due to the backward movement of the sub piston 03.

As described above, when the opening speed of the throttle valve (9) exceeds a predetermined value during the opening operation of the throttle valve (9), the ignition timing is retarded by an appropriate amount of time. Therefore, the ignition timing retard amount 1i111 can suppress the occurrence of knocking caused by the backward delay of the auxiliary piston 03 at the beginning of acceleration of the engine. When the sub-piston plate 12 has retreated to its predetermined position after a certain period of time has elapsed, the ignition timing retard control is canceled.

At the time of ignition 1 (11) during this acceleration
When the opening angle of the throttle valve per unit time is large, the retard amount and retard time are increased and the throttle valve opens slowly!・When the opening angle per unit time of the valve is small, it is more effective to reduce the amount of retardation and the retardation time by 1. To return the timing to retard one company zero after an appropriate time, set f within the relevant time.
It is also possible to return to a sequential or stepless slope.

Moreover, instead of directly retarding the ignition timing "C" based on the output signal from the throttle valve opening speed detection circuit 0 as in the above embodiment, as shown in FIG. Throttle valve opening speed detection circuit (32 and ignition timing control circuit 01)
A knock discrimination circuit (C) is interposed between the engine and the engine, and the knock discrimination circuit (7) receives the acceleration signal from the throttle valve 011 speed detection circuit 02. Then, it is possible to detect the presence or absence of knocking in the engine, issue a retard signal for the ignition timing only when there is knocking, and retard the ignition timing until the ignition timing stops knocking. Since the ignition timing retard control can be performed only when knocking occurs during acceleration of the engine, the reduction in output due to the ignition timing retard control can be minimized.

In addition, in the above embodiment, the hydraulic chamber 0'I) has 1! , 1.
As the hydraulic oil to be supplied, lubricating oil in an engine, hydraulic oil in a power steering system of an automobile, or hydraulic oil in an automatic transmission of an automobile can be used. Although a ring (A) is shown, as shown in FIG. 4, the stem (16a) is formed into a hollow shaft, and the spill rod (22a) is slidably inserted into the stem (16B). The spill boat (21a) may be configured to be opened and closed by sliding the spill boat (22a) using an actuator related to the load of the engine, or as shown in FIGS. 5 and 6. The spill boat in the stem (16b) is formed into an inclined or inclined spill boat (21b) with respect to the axis of the stem (16b).
It6b) has a float-style spill ring (221) on the outer periphery.
) is rotatably and slidably fitted on the spill ring (22
b) is pivotally supported on the cylinder head (2) by a bearing (not shown), and this spill ring (22b) has a stem (
16b) slides back and forth, its inclined spill port 1.
One missed ball 1- matching (21b)
In addition to installing 7 (g), this spill ring (22b)
In the evening (m+, Ii @), rotate the spill ring (22b) by sliding it in the direction of Nagai with the Stella (c), and release it against the inclined spill port I- (21b) of the stem (16b). The compression ratio may be automatically controlled by shifting the boat to the q) position or the q) position.

Although embodiments have been described above, the present invention is a variable compression ratio type in which a sub-piston is inserted into a sub-cylinder communicating with a combustion chamber, and the sub-piston is moved back and forth by hydraulic pressure according to the load of the engine. In an internal combustion engine, the ignition timing is retarded by an appropriate amount of time when the throttle valve in the intake passage to the combustion chamber is suddenly opened. When the secondary piston of the engine is moved back and forth by hydraulic pressure, it is possible to reliably prevent knocking from occurring due to a delay in controlling the compression ratio to low when the engine is accelerating. This means that there is no reduction in performance or deterioration of drivability.

Further, the second invention of the present application performs retard control of the ignition timing during acceleration in accordance with the actual knocking state during acceleration, so in addition to the first invention,
This has the effect of reducing the number of times the output is reduced due to ignition timing retard control.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional front view of the main parts of the engine, and FIG. 2 is a third view taken along line II-II in FIG.
The figure is a diagram of another example of the control system, FIGS. 4 and 5 are diagrams of another example of a spill body and a spill port, and FIG. 6 is a plan view of FIG. 5. (1)...Cylinder block, (2)...Cylinder head, (5)...Combustion chamber, (6)...Ignition plug, (
8)...Intake port, (10)...Intake passage, (
9)...Throttle valve, 111 units...Secondary cylinder, /ri,
θ■...Sub-piston, α...Hydraulic chamber, (161(
16a) (161)) ... Stem, 0υ (21a) (
21b) --- Spill port, <2J (22a) (22
b)... Spill body, (a)... Actuator, G1
)...Ignition timing control circuit, 0]...Throttle valve positioner, 0...Throttle valve opening speed detection circuit, ■...2 Knock sensor, (C)...Knock discrimination circuit. For patent +yr1 person Daihatsu Motor Co., Ltd. 21b
36 Figure 5

Claims (2)

[Claims] (1) The ignition timing of the auxiliary piston in the auxiliary cylinder communicating with the combustion chamber is retarded by an appropriate amount of time when the throttle valve in the intake passage to the combustion chamber is suddenly opened. A variable compression ratio internal combustion engine featuring: (2) The j14 angle jij and . Compression ratio i? J-variable internal combustion engine 3), a compression ratio in which an auxiliary piston is inserted into an auxiliary cylinder that communicates with the combustion chamber, and the auxiliary piston 42 is moved back and forth by hydraulic pressure according to the load of the auxiliary piston 42b'=1. In a variable internal combustion engine, knocking at the time of sudden opening of a throttle valve in the intake passage to the combustion chamber IX is detected, and the ignition timing of the engine is retarded in response to the knocking. A variable compression ratio internal combustion engine.