JPH08177536A - Valve timing control method and control device - Google Patents

Abstract

PURPOSE: To improve thermal efficiency by making the opening/closing timing of a rotary valve and intake-exhaust valves variable according to engine operating conditions in a Miller cycle engine or an engine with a rotary valve interposed at the intermediate part of an intake pipe. CONSTITUTION: An intake valve opening/closing timing control means for rotating the camshaft 19a of a driving cam 19 for an intake valve 15 by an actuator 4' such as a stepping motor is provided including a valve timing control means for making the opening/closing timing of a rotary valve 3 quicker-closing than the normal opening/closing timing of intake-exhaust valves 15, 16 by an actuator 4 such as a stepping motor on the basis of input information from a rotation sensor 7, a load sensor 8, a crank angle sensor 9, an intake pressure sensor 2a and an exhaust pressure sensor 18a, and the valve opening/closing timing is controlled to the optimum in correspondence with an operating state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing control of an engine in which a rotary valve is provided in the middle of a Miller cycle or an intake pipe.

A Miller-cycle engine is a rotary valve installed in the intake pipe before the intake valve is closed, for example, by "early closing" to increase the expansion ratio with respect to the compression ratio. By varying the stroke from intake to compression, the energy of the combustion gas is fully expanded and taken out.

[0003]

Rotary valves are used in Miller cycle or engines that do not have a throttle valve.
However, the rotary valve is variable depending on the output, but the intake / exhaust valve timing is constant.

[0004]

The following points are problems in the above-mentioned Miller cycle.

(1) If the rotary valve is closed earlier than the intake valve, the amount of intake air is reduced, which limits the output. (2) Since the overlap of the intake / exhaust valves cannot be changed, it is not possible to operate in the optimum state depending on the load, that is, when the load is low, the overlap is small and when the load is high, the overlap is large. . (3) If the boost pressure is too high, the waste gate is opened to bypass the supercharger and the exhaust energy is discarded to the exhaust pipe.

The present invention has been proposed in view of the above problems of the prior art. In a Miller cycle engine or an engine in which a rotary valve is provided in the middle of an intake pipe, the rotary valve and the intake valve are arranged in accordance with the output of the engine. An object of the present invention is to provide a valve timing control method and a control device for improving thermal efficiency by making the opening / closing timing of an exhaust valve both variable.

[0007]

According to the valve timing control method of the present invention, in the valve timing control method for an engine having a rotary valve, the rotary valve is closed earlier than the normal opening / closing timing of the intake valve. A rotary valve timing control step and an intake valve timing control step of changing the opening / closing timing of the intake valve in response to opening / closing of the rotary valve in order to reduce the compression ratio without changing the intake air amount are included.

Here, the relative relationship between the intake valve operating crank and the exhaust valve operating crank can be adjusted,
During low load operation, the phase is changed to accelerate the opening and closing of the exhaust valve so that the valve overlap is reduced to suppress exhaust blowback, and during high load operation, the valve overlap is increased to effectively use the exhaust interference. As described above, it is preferable to change the phase in a direction that delays the opening and closing of the exhaust valve. Alternatively, in the engine, the relative relationship between the intake valve operating crank and the exhaust valve operating crank can be adjusted, and the intake valve opening / closing is performed to reduce the valve overlap in order to suppress exhaust blowback during low load operation. Change the phase to delay
During high load operation, it is preferable to change the phase in a direction to accelerate the opening and closing of the intake valve so as to increase the valve overlap in order to effectively use the exhaust interference.

Further, the engine is an engine with a supercharger, and preferably includes a phase control step of changing a phase in a direction of delaying opening / closing of an exhaust valve when boost pressure (supercharging pressure) is too high. .

Furthermore, the valve timing control method of the present invention is a valve timing control method for an engine in which a rotary valve is interposed, in which the phase is changed in a direction that accelerates the opening and closing of the intake valve during low speed operation, and the intake valve The phase is changed to delay opening and closing.

The valve timing control device of the present invention is an engine valve timing control device in which a rotary valve is interposed, and an actuator for driving an intake / exhaust valve, a rotation sensor, a load sensor, a crank angle sensor,
Based on various input information from the intake pressure sensor and exhaust pressure sensor, the opening / closing timing of the rotary valve can
A rotary valve timing control means for early closing with respect to the opening / closing timing of the exhaust valve, and an opening / closing timing of the intake valve in response to opening / closing of the rotary valve in order to reduce the compression ratio without changing the intake air amount. And an intake valve timing control device.

Here, in the engine, the relative relationship between the intake valve operating crank and the exhaust valve operating crank can be adjusted, and the control means and actuator control the valve over to suppress exhaust blowback during low load operation. The phase is changed to accelerate the opening and closing of the exhaust valve so as to reduce the wrap, and in order to effectively utilize the exhaust interference during high load operation, the phase is changed to delay the opening and closing of the exhaust valve to increase the valve overlap. It is preferable to change. Alternatively, in the engine, the relative relationship between the intake valve operating crank and the exhaust valve operating crank can be adjusted, and the control means and the actuator reduce the valve overlap in order to suppress exhaust blowback during low load operation. In this way, changing the phase in the direction that delays the opening and closing of the intake valve, and changing the phase in the direction that accelerates the opening and closing of the intake valve to increase the valve overlap in order to effectively use exhaust interference during high load operation. preferable.

Further, the engine is an engine with a supercharger, and preferably includes a phase control means for changing the phase in a direction of delaying the opening / closing of the exhaust valve when the boost pressure (supercharging pressure) is too high.

Further, the valve timing control device of the present invention is an engine valve timing control device in which a rotary valve is interposed, and an actuator for driving intake and exhaust valves, a rotation sensor, a load sensor, a crank angle sensor, an intake pressure sensor, and An intake / exhaust valve timing control device that changes the phase in a direction that accelerates the opening and closing of the intake valve during low-speed operation, and changes the phase that delays the opening and closing of the intake valve during high-speed operation based on various input information from the exhaust pressure sensor , And.

[0015]

According to the valve timing control method of the present invention, the intake air amount is changed by changing the opening / closing timing of the intake valve in response to opening / closing of the rotary valve in, for example, a so-called mirror cycle using the rotary valve. The compression ratio can be improved without changing. As a result, the thermal efficiency can be improved.

Further, in the case of an engine in which the relative relationship between the intake valve operating crank and the exhaust valve operating crank can be adjusted, the range of overlap can be adjusted to achieve optimum operation for the load. It is possible to adjust the phase of the intake valve opening and closing to achieve optimum operation for rotation. For example, when the load is low, the overlap of the intake / exhaust valve is reduced to suppress the blowback of exhaust gas, and by increasing the overlap of the intake / exhaust valve at high rotation / high load, the intake inertia effect is used to take in the intake air. The effect is improved. In this way, the thermal efficiency is improved with the optimum valve timing depending on the operating conditions.

Further, according to the present invention, the phase is changed in a direction to accelerate the opening / closing of the intake valve during the low speed operation to suppress the blowback of the intake air, and the phase is changed in the direction to delay the opening / closing of the intake valve during the high speed operation. The supercharging effect can be brought out.

[0018]

Embodiments of the present invention will be described below with reference to FIGS. In the illustrated embodiment, the engine indicated by reference numeral 1 is an engine in which the relative relationship between the intake valve operating crank and the exhaust valve operating crank can be adjusted.

In FIG. 1, an engine 1 has a cylinder 11 on which an internal wall is slidable by a piston 13, a cylinder head 12 located above the cylinder and having an intake port 17 and an intake port 18, the intake port 17 and the cylinder head 12. An intake valve 15 and an exhaust valve 16 that open and close the respective openings of the exhaust port 18 on the cylinder side, and an intake pipe 2 in which a rotary valve 3 that opens and closes a pipeline is provided in the middle.

Further, the engine 1 is provided with a rotation sensor 7, a load sensor 8, a crank angle sensor 9, an intake pressure sensor 2a, and an exhaust pressure sensor 18a, and a control unit based on input information from them. Reference numeral 6 designates the drive of the actuator 4 ′ for driving the rotary valve 3 and the actuator 4 ′ for rotating the cam shaft 19a of the drive cam 19 for the intake valve 15, that is, the valve opening / closing timing is optimized for the operating condition at that time. Control.

Next, the valve timing control flow of FIG. 3 will be described with reference to FIGS. 1 and 2.

First, at step S1, the engine speed is detected by the rotation sensor 7 and the load sensor 8 is detected.
The engine load is detected by and the routine proceeds to step S2, where the intake pressure sensor 2a detects the intake pressure and the exhaust pressure sensor 18a detects the exhaust pressure. Further, the process proceeds to step S3, the crank angle is detected by the crank angle sensor 9, the respective input information is read into the control unit 6, and the operating condition at that time is confirmed. on the other hand,
The operating condition map that has been read in advance is called (step S4), compared with the operating condition at that time point, and the process proceeds to step S5, in which the actuator for optimally controlling the rotation angle (phase) and the opening / closing speed of the rotary valve 3. A controlled variable of 4 is determined and executed.

That is, as shown in the valve lift diagram of FIG. 2, when the engine is operating in the low load region or low compression ratio, the opening / closing timing of the rotary valve is advanced as indicated by line c '.

Next, in step S6, the exhaust valve 16
The control amount of the actuator 4'is determined and executed so as to optimally control the opening / closing of the intake valve 15 with respect to the opening / closing of.

That is, when the load is low, the opening and closing of the intake valve 15 is delayed as shown by line a in FIG. 2 (to reduce the overlap), and when the rotation speed is high and the load is high, the opening and closing of the intake valve 15 is accelerated to prevent the overlap. Not only does it take a large value, but also the reduction of the intake air amount due to the change of the opening / closing timing of the rotary valve from c to c ′ is improved. Then control returns to the original.

In FIG. 4, as an embodiment of other valve operating mechanisms for the intake valve and the rotary valve in the middle of the intake pipe, and means for adjusting the valve timing of the valve, an exhaust turbine driven type upstream of the intake manifold 2'is shown. In an engine 1'having a supply system 20, a rotary valve 3 is arranged in the intake manifold 2'which is connected to an intake port as a control valve driven from a crankshaft of the engine via a gear transmission mechanism. The rotary valve 3 is fixed to a drive shaft 31, and the drive shaft 31 is provided with an adjusting piece 35 of valve timing adjusting means on a rotary shaft 34 driven by a gear 33 that is transmission-coupled to a crank shaft via a gear mechanism. Are connected through.

Next, regarding the structure of the opening / closing timing adjusting means of the rotary valve 3, helical splines 31a and 34a are formed in opposite parts of the drive shaft 31 and the rotary shaft 34, respectively, with twists in opposite directions. Protrusions (not shown) formed on the inner periphery of the adjustment piece 35 mesh with the helical splines, and the drive shaft 31 is moved relative to the rotary shaft 34 by moving the adjustment piece 35 to the left in FIG. Is angularly displaced in the direction of and is moved to the left to be angularly displaced in the opposite direction. In this way, the rotation timing of the drive shaft 31 is changed by the axial movement of the adjustment piece 35, and the opening / closing timing of the rotary valve 3 is adjusted.

The movement of the adjustment piece is carried out by moving the adjustment lever 36 on the actuator 41 side, one end of which is engaged with an annular locking groove 35c formed on the outer circumference of the adjustment piece. Further, the method of adjusting the valve timing of the intake valve is exactly the same as the method of adjusting the valve timing of the rotary valve 3 described above, and a description thereof will be omitted.

[0029]

As described above, according to the valve timing control method of the present invention, the opening / closing timing of the intake valve is suitably controlled, and the compression ratio relative to the expansion ratio is achieved by the so-called mirror cycle early closing effect of the rotary valve. The thermal efficiency can be improved by reducing the ratio of.

Further, when the load is low, the overlap of the intake / exhaust valves is reduced to suppress exhaust blowback,
The intake effect can be increased by utilizing the exhaust inertia effect by increasing the overlap between the intake and exhaust valves at high load.

Further, during low speed operation, the phase is changed in such a direction as to accelerate the opening and closing of the intake valve to suppress the blowback of intake air,
During high-speed operation, the phase can be changed in the direction that delays the opening and closing of the intake valve to bring out the inertia supercharging effect.

[Brief description of drawings]

FIG. 1 is a diagram showing a system configuration according to an embodiment of the present invention.

FIG. 2 is a valve opening characteristic diagram including a rotary valve.

FIG. 3 is a valve timing control flow according to an embodiment of the present invention.

FIG. 4 is a diagram showing a system configuration according to another embodiment of the present invention.

[Explanation of symbols]

 1, 1 '... Engine 2 ... Intake pipe 3 ... Rotary valve 2a ... Intake pressure sensor 3a ... Rotary valve shaft 4, 4' ... Actuator 6 ... Control unit 7 ... ..Rotation sensor 8 ... Load sensor 9 ... Crank angle sensor 11 ... Cylinder 12 ... Cylinder head 13 ... Piston 15 ... Intake valve 16 ... Exhaust valve 17 ... Intake Port 18 ... Exhaust port 18a ... Exhaust pressure sensor 19 ... Cam 19a ... Cam shaft 20 ... Supercharger 41, 42 ... Actuator

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location F02B 29/08 G 37/00 302 A

Claims (10)

[Claims] 1. A valve timing control method for an engine including a rotary valve, wherein a rotary valve timing control step of closing the rotary valve earlier than a normal intake valve opening / closing timing and an intake air amount are changed. A valve timing control step of changing the opening / closing timing of the intake valve in response to the opening / closing of the rotary valve in order to reduce the compression ratio. 2. In the engine, the relative relationship between the intake valve operating crank and the exhaust valve operating crank can be adjusted, and the exhaust gas is reduced so that the valve overlap is reduced in order to suppress exhaust gas blowback during low load operation. 2. The valve according to claim 1, wherein the phase is changed in a direction to accelerate the opening / closing of the valve, and the phase is changed in a direction to delay the opening / closing of the exhaust valve so as to increase the valve overlap in order to effectively utilize the exhaust interference during high load operation. Timing control method. 3. The engine is capable of adjusting a relative relationship between an intake valve operating crank and an exhaust valve operating crank, and intake valves are designed to reduce valve overlap in order to suppress exhaust blowback during low load operation. 2. The valve according to claim 1, wherein the phase is changed in a direction that delays opening and closing of the valve, and the phase is changed in a direction that accelerates opening and closing of the intake valve so as to increase valve overlap in order to effectively utilize exhaust interference during high load operation. Timing control method. 4. The engine according to claim 1, further comprising a phase control step of changing a phase in a direction of delaying opening / closing of an exhaust valve when the supercharging pressure is too high. The valve timing control method according to item 1. 5. A valve timing control method for an engine including a rotary valve, wherein a phase is changed in a direction to accelerate opening / closing of an intake valve at a low speed operation, and a phase is changed to delay opening / closing of an intake valve in a high speed operation. A valve timing control method comprising: 6. An engine valve timing control device equipped with a rotary valve, wherein various input information from an actuator for driving an intake / exhaust valve, a rotation sensor, a load sensor, a crank angle sensor, an intake pressure sensor and an exhaust pressure sensor. Based on the above, the rotary valve timing control means for opening and closing the rotary valve earlier than the normal intake and exhaust valve opening and closing timing, and the rotary valve for reducing the compression ratio without changing the intake air amount. An intake valve timing control device for changing the opening / closing timing of an intake valve in response to opening / closing of the valve, and a valve timing control device. 7. The engine is capable of adjusting a relative relationship between an intake valve operating crank and an exhaust valve operating crank, and the control means and the actuator have a valve overlap for suppressing exhaust blowback during low load operation. To change the phase so that the opening and closing of the exhaust valve is accelerated to make it smaller, and to change the phase to delay the opening and closing of the exhaust valve to increase the valve overlap in order to effectively use the exhaust interference during high load operation. Item 6
Valve timing control device. 8. The engine is capable of adjusting a relative relationship between an intake valve operating crank and an exhaust valve operating crank, and the control means and the actuator have a valve overlap to suppress exhaust blowback during low load operation. Change the phase in a direction that delays opening and closing of the intake valve to make it smaller, and change the phase in a direction that accelerates opening and closing of the intake valve so as to increase valve overlap in order to effectively use exhaust interference during high load operation. Item 6
Valve timing control device. 9. The engine according to claim 6, further comprising a phase control means for changing a phase in a direction of delaying opening / closing of an exhaust valve when the supercharging pressure is too high. The valve timing control device according to item 1. 10. A valve timing control device for an engine having a rotary valve, wherein actuators for driving intake and exhaust valves and various input information from a rotation sensor, a load sensor, a crank angle sensor, an intake pressure sensor and an exhaust pressure sensor. And an intake / exhaust valve timing control device that changes the phase in a direction that accelerates opening and closing of the intake valve during low-speed operation, and changes the phase that delays opening and closing of the intake valve during high-speed operation. Valve timing control device.