JPH02308909A - Valve opening/closing control device for engine - Google Patents

Abstract

PURPOSE:To improve engine efficiency in a wide range of operating condition by providing a control means for receiving outputs of a valve opening/closing timing detecting means and a valve opening/closing timing command means to output a control signal to a rotational phase angle changing means. CONSTITUTION:An opening/closing timing detecting circuit 70 receives an electric signal from a detecting circuit unit 60 to output a pulse signal when an inlet valve 2 is opened or closed. An opening/closing timing command circuit 90 receives information on the operating conditions from an engine operating condition detecting means 100 to determine an optimum valve opening/closing timing to generate a target-value signal. A comparison control circuit 80 compares a signal from the detecting circuit 70 to a signal from the opening/ closing timing command circuit 90 to send out a control signal to a drive control circuit included in a phase angle changing means 22 so that the difference between both the signals becomes zero. Thus, since the rotational phase angle of a cam driving shaft 11 can be changed and controlled so that a detected timing and a desired timing of opening/closing timing of the valve during operation coincide with each other, engine efficiency can be improved in a wide range of operating condition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a valve opening/closing control device for an engine installed in an automobile or the like.

[Conventional technology]

Generally, the timing of opening and closing the intake and exhaust knobs in an internal combustion engine has a large effect on the efficiency of filling intake air into the cylinder, and must be selected appropriately depending on the rotational speed of the engine and the conditions of the intake pipe and exhaust pipe.

For this reason, in an internal engine equipped with a conventional cam-driven valve mechanism, the knob is adjusted so that it can operate at an optimal state (maximum efficiency) at a specific engine speed and torque, for example, at rated output. The opening/closing timing is set fixedly.

However, such a fixed setting has the disadvantage that when the engine is operated at low load, exhaust gas blows back, reducing the efficiency of the engine and causing a deterioration of the fuel consumption rate and exhaust components. This problem can be avoided by shortening the over-ramp period of the intake and exhaust valves, but this results in the inconvenience that the scavenging efficiency and intake efficiency decrease under high load or high speed rotation.

Therefore, as a solution to these problems, two intake valves are provided, and the cams that drive each of these intake valves are made to have different expansion and softness, so that opening and closing with a large overlap with the exhaust valve and opening and closing with a small overlap are achieved. A device has been proposed which is equipped with a switching mechanism for setting and switching the two intake valves so that they are selectively driven, and switching the two intake valves according to the load.

In addition, by using a variable valve timing device such as that disclosed in, for example, Japanese Unexamined Patent Publication No. 59-160016 or Japanese Utility Model Application No. 59-133704, it is possible to adjust the valve timing to any value within a predetermined range depending on the operating state of the engine. A device has been proposed that can open and close an intake valve or an exhaust valve at timings of 1 to 1, thereby improving engine efficiency.

[Problem to be solved by the invention]

However, in conventional valve opening/closing devices, in the former device using two intake valves, the valve opening/closing timing for each of the two intake valves is fixed, and depends on all engine operating conditions. However, there is a problem in that it is difficult to set the optimal opening/closing timing. In addition, in the case of a device like the latter device, which can set arbitrary opening/closing timing, there is no problem such as having two parts, but it is necessary to directly detect the opening/closing timing of a variably set valve. ,
Since the drive is set indirectly based on the variable setting of the operating oil pressure of the mechanical part and the position of the movable part +2, there is a problem with accuracy, especially when the valve opening/closing timing changes due to changes in the various parts of the mechanism over a long period of use. Setting errors become an unavoidable problem. In addition, due to variations in the parts used, in order to maintain the accuracy of the final valve opening/closing timing, it is necessary to strictly control the precision of each part, which increases costs.

This invention was made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a valve opening/closing control device that can improve engine efficiency under a wide range of operating conditions and is also low-cost and highly accurate. With the goal.

[Failure to solve the problem]

An engine valve opening/closing control device according to the present invention includes a cam that opens and closes an intake valve or an exhaust valve of an engine, a cam drive shaft that rotates the cam in synchronization with engine rotation, and a rotation of this cam drive shaft. a phase angle changing means for changing the phase angle; a valve opening/closing timing detecting means for detecting the opening/closing timing and closing timing of the intake valve or exhaust valve; An opening/closing timing command means for commanding the opening/closing timing, and a control signal to the phase angle changing means so that the opening/closing timing of the valve is at the commanded timing in response to the output of this command means and the output signal of the valve opening/closing timing detection means. The invention is characterized by comprising a control means for outputting.

[For production]

In this invention, while detecting the opening/closing timing of the valves in operation so as to set the opening/closing timing of the intake and exhaust valves of the engine to the optimum timing according to the operating condition of the engine, at the time of this detection, the
The rotational phase angle of the cam drive shaft that opens and closes the valve can be changed and controlled so that ll coincides with a desired timing.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram of the valve opening/closing control device for an engine according to the present invention, FIGS. 2 and 3 are schematic diagrams of the main parts of the valve opening/closing control device, and FIG.

FIG. 3 is a schematic diagram of main parts of the exhaust mechanism. In each of these figures, the reference numeral 1 has the engine crankshaft, and the intake/exhaust valves 2 and 2 driven by this crankshaft 1 are
3 is a cylinder tab and is arranged in the second part of the dock 4.

These intake and exhaust valves 2 and 3 are connected to an intake pipe 7 and an exhaust pipe 8 that communicate with a combustion chamber 6 formed above the piston 5.
It is provided on the edge of the opening so that it can move forward and backward. Reference numerals 9 and 10 indicate cams that drive the intake and exhaust valves 2 and 3, respectively. These cam drive shafts], ], +' 1.2 and cam 9.
Reference numeral 10 constitutes an intake/exhaust knob mechanism that drives the valve. 13 is a throttle valve, and 14 is a spark plug.

] 5 is a pulley mounted on one end of the force J/drive shaft, in the embodiment, the cam drive shaft 11; 16 is a boolean mounted on one end of the other cam drive shaft 12; A timing belt 18 is passed between the side pulley 16 and a pulley 17 mounted on the crankshaft 1, and the cam drive shaft 12 is connected to the crankshaft 1 via this timing belt 18. There is. The pulley 15 to the timing belt 18 constitute a rotation transmitting section 21 in the block diagram of FIG.
2 has been proposed in the past, and examples of specific means are shown in FIGS. 2 and 5. In these figures, 19 is the pulley 1 on the intake side.
The timing belt 19 is attached to the pulley 15 and the differential gear 20. The differential gear device 20 includes a central shaft 33 supported by a bearing 21, and a pair of bevel gears 23, 24 rotatably provided on the central shaft 33 to face each other.
It is comprised of pinions 26 and 27 rotatably provided on a pinion shaft 25 that meshes with these bevel gears 23 and 24 and extends transversely through the center shaft 33. Said pinio 7.
Both ends of the heel 25 are formed into an annular shape, as shown in FIG.
is fixed to a pulley 28 to which is attached. Further, teeth 23 constituting spur gears are provided on the outer peripheral surface of the bevel gears 23 and 24.
The teeth 23a of the bevel gear 23 are engaged with a gear 29 that is mounted on the end of the crankshaft 1 and rotates in the same phase as the crankshaft 1, and the teeth 24a of the bevel gear 24 are
is meshed with a gear 32 mounted on a rotating shaft 31 of the actuator 3o.

This actuator 3o is activated by the gear 32 by an electric signal.
By rotating the bevel gear 24 with respect to the bevel gear 23, the phase of the pulley 28 is controlled to be out of phase with the phase of the crankshaft 1.

That is, the cam drive shaft 11 and the actuator 30
It is connected to the crankshaft 1 via a differential gear device 20 that is controlled by the rotation of the crankshaft 1. The differential gear device 20 is configured to use the rotation of the gear 29 and the rotation of the gear 32 as original motions, and output the resulting slave motion from the pulley 28 to the cam drive shaft 11. A drive control circuit 36 generates a drive signal for driving the actuator 30, and responds to an output signal from a comparison control circuit, which will be described later.

FIG. 3 is a schematic diagram of the I/Lux detection section in FIG.
The intake valve 2 is opened when the eccentric protrusion of the cam 1i comes into contact with the valve tappet surface. Reference numeral 40 is a bearing that rotatably supports the cam drive shaft 11, and 50 and 60 constitute a detection circuit section that detects torque changes in the rotational direction of the cam drive shaft 11 and outputs an electric signal. Of these, 50 are strain detection units that detect stress and strain due to the rotational driving force on the cam drive shaft 11.
As disclosed in Japanese Patent No. 2-182713, etc., a device that detects the stress strain of a rotating shaft with high sensitivity in a non-contact manner is suitable. 51a and 51b are magnetostrictive materials in the form of thin plates or thin films provided on the circumferential surface of the cam drive shaft 11 by bonding or plating, and 52a and 52b are magnetostrictive materials that resist stress and strain caused by the torque applied to the cam drive shaft 11. This is a detection coil that detects the amount of change in magnetic permeability of the magnetostrictive material that changes accordingly, and consists of a coil wire and a bobbin around which the wire is wound. 5
38 to 53c, the above two detection coils 52a and 52b
The lead wires connect the detection circuit section 60 and the detection coils 52a, 5.
2b is electrically connected.

The detection circuit section GO consists of an oscillation circuit, a drive circuit that drives the current flowing to the detection coil, a differential amplifier circuit, a phase detection circuit, etc. Study group materials, document number M
A, G-88-158J, etc., so a detailed explanation will be omitted.

Reference numeral 70 denotes a valve opening/closing timing detection circuit which receives an electric signal from the detection circuit section 60 and outputs a pulse signal when the intake valve 2 is opened or closed. In FIG. 1, 80 indicates a signal from the two-part opening/closing timing detection circuit 70 and a valve opening/closing timing command circuit 90.
This is a comparison control circuit which sends a control signal to the drive control circuit 36 in FIG. 5 included in the phase angle changing means 22 so that the deviation becomes zero by comparing the signals from the phase angle changing means 22. The valve opening/closing timing command circuit 90 receives operating information from the engine operating state detecting means 100, determines the optimum valve opening/closing timing, and generates a target value signal related to the valve opening/closing timing in the comparison control circuit 80. A specific method for determining this is, for example, by storing an optimal value determined in advance according to the engine speed and load, and then sequentially selecting the above value upon receiving information regarding the engine speed and load when the engine is running. A map method that reads and outputs the data stored in the engine, or inputs information related to the cylinder pressure of the engine as engine operating status information, so that combustion within the engine cylinders is performed at maximum efficiency for each operating status. This is achieved by using a program to quickly calculate or learn the optimum value for the opening or closing timing of the intake or exhaust valve, and then sequentially determining the optimum valve opening/closing timing based on this learned value.

Next, the operation of the apparatus shown in FIG. 1 will be explained with reference to FIGS. 6 to 8. Here, in order to make the operation easier to understand, the opening/closing operation of the intake valve of one cylinder in the engine will be explained.

Similar operations are performed for other cylinders and exhaust valves of the engine one after another on the time axis. FIG. 6 schematically shows, on the time axis, one operation of the main parts during the control operation regarding the opening time 71i of the intake valve. Here, the sixth
Figure fa+ shows a command signal for the valve opening timing, and Figure (b) shows a target command pulse for the intake valve opening timing generated inside the comparison control circuit 80 with reference to the crank angle pulse signal corresponding to the fat diagram. . +Cl diagram shows the intake valve opening timing detection pulse output from the valve opening/closing timing detection section 70.

First, the operation until the above detection pulse is obtained will be explained. FIG. 7 is a diagram (a) showing the change in lift amount of the intake valve or exhaust valve when the rotation angle of the cam drive shaft 11 (equivalent to /2 of the rotation angle of the crankshaft) is plotted on the horizontal axis, and the detection circuit section 60 2 is an example of an output signal fbi diagram and an operation waveform of an output signal of the valve opening/closing timing detection circuit 70. Valve opening/closing timing detection circuit 70
For example, (receive a signal as shown in figure b1, calculate the temporal rate of change of this signal, and if the result is greater than a predetermined value,
Outputs a pulse with a predetermined time width. As shown in Fig. 7 (b) above, corresponding to the large change in I/rook of the cam drive shaft 11 when the valve starts to lift and the large change in torque when the valve is seated, Fig. (By outputting a pulse signal such as C1, the opening/closing timing of the valve is detected.The torque signal waveform shown in the above diagram Cb1 is based on the engine operating condition (rotation speed and load size), engine temperature, Although the magnitude and average level change depending on the properties of the lubricating oil, the rate of change in torque when the valve starts to lift or seats is considerably different from the rate of change in torque during other operating states of the valve. There is a difference, and there is no problem in detecting the opening/closing timing of the valve.

In addition, the peak point of the torque output is considered to be the point at which the lift of the valve starts as the opening/closing timing of the valve, and the lift amount of the valve reaches approximately 1/2 of the maximum value (Fig. 7 fa), [b)).
It is also possible to detect this and output a pulse signal (FIG. 7(d)) as the valve opening timing and valve closing timing. In this way, the detection pulse of the opening timing of the intake valve (Fig. 6 (C)
) is obtained.

Next, the operation of the comparison control circuit 80 in response to the intake valve opening timing command signal R8P will be explained. The control output ■ is as shown by the solid line in FIG. 8 as an initial setting value corresponding to the target command signal R8. p is stored in the comparison control circuit 8o, and a control output signal I is sent to the phase angle changing means 22 according to the relationship between the two. P is sent out, and the rotational phase angle of the cam drive shaft 11 with respect to the crankshaft is changed according to this signal, and as a result,
The opening timing of the intake valve is changed according to the target command value. However, as the engine progresses, the actual opening timing deviates from the target value as shown in FIG. 6(C) due to changes in the valve opening/closing mechanism over time as described above. For example, the deviation amount EOP is set as the deviation amount EOP in correspondence with the target command value R8 at that time. , R84 and I in FIG. , is added or subtracted as the amount of correction of the correspondence relationship. Therefore, the initial setting (solid line in Figure 8) is corrected by comparative control as shown by the broken line, and the actual operation uses this corrected relationship to determine the opening timing of the valve. The opening and closing operations of the valve will be performed in accordance with the opening timing of the target command. Therefore, R8. The relationship between and ror is stored in the comparison control circuit, and the storage method may be electrical or mechanical. It is best to configure the system with a microcomputer or the like. In addition, in that case, ``R
It is desirable to remember the relationship between 6P and 1° even when the power is cut off.

〔Effect of the invention〕

As explained above, according to the present invention, there is provided a phase angle changing means for changing the rotational phase angle of a cam drive shaft that rotationally drives a cam that opens and closes an intake valve or an exhaust valve of an engine; The output of the valve opening/closing timing detecting means and the opening/closing timing commanding means is provided with a valve opening/closing timing detecting means for detecting the valve opening/closing timing, and an opening/closing timing commanding means for commanding the opening/closing timing of the intake and exhaust valves according to the operating state of the engine. The structure is configured so that the opening and closing timing of the intake and exhaust valves is adjusted according to the command through the rotational phase angle changing means by receiving the LJ, so engine efficiency can be improved in a wide range of operating conditions, and accuracy can be achieved at low cost. It is possible to obtain a valve opening/closing control device that is high in price and has little deterioration over time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a valve opening/closing control device according to an embodiment of the present invention, FIGS. 2 and 3 are schematic diagrams of the main parts of the valve opening/closing control device, and FIG. 4 is a main part of the intake and exhaust mechanism. Fig. 5 is a schematic diagram of the phase angle changing means; Fig. 6 is a schematic diagram of the phase angle changing means;
The figure is a control operation diagram for the opening timing of the intake valve, Figure 7 is a diagram of the output signal and pulse signal of the valve opening/closing timing detection circuit with respect to the rotation angle of the cam drive shaft, and Figure 8 is a diagram of the command signal R81 and the pulse signal for the opening timing of the intake valve.
and control output ■. , is a relationship diagram. 2... Intake valve, 9... Cam, 11... Cam drive shaft, 22... Phase angle changing means, 70... Opening/closing timing detection circuit, 80... Comparison control circuit, 90... Opening/closing timing command circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] A cam that opens and closes the intake or exhaust valve of the engine,
A cam drive shaft that rotationally drives the cam in synchronization with the rotation of the engine, a phase angle changing means that changes and drives the rotational phase angle of the cam drive shaft, and opening timing and closing timing of the intake valve or exhaust valve. a valve opening/closing timing detection means for detecting the opening/closing timing of the valve, an opening/closing timing commanding means for commanding the opening/closing timing of the intake valve or the exhaust valve according to the operating state of the engine, an output of the commanding means, and an output of the valve opening/closing timing detection means. A valve opening/closing control device for an engine, comprising: a control means for receiving a signal and outputting a control signal to the phase angle changing means so that the valve opening/closing timing is at the commanded timing.