JPS61108817A - Control device for opening and closing valve in internal combustion engine - Google Patents

Abstract

PURPOSE:To assure optimum timing of opening and closing a valve by driving a rotary shaft being a cam drive shaft by means of a differential gear device employing as a primer movement rotation of a rotary shaft rotating in the same phase as a crank shaft and rotation of a rotary shaft driven by a stepping motor. CONSTITUTION:Cam drive shafts 12 13 being a second rotary shaft serving to drive any of a suction valve or an exhaust valve for opening and closing them are driven by a crank shaft 14 of an internal combustion engine via a differential gear device 20. The differential gear device 20 employs as a prime mover a gear 21a mounted on a first rotary shaft 21 rotating in the same phase as the crank shaft 14 and a gear 22a mounted on a third rotary shaft 22 integrally therewith driven by a stepping motor 23 controlled in its phase and rotated by a signal from a control circuit 33 and drives a timing belt 19 by making use of a driven gear thereof. Hereby, the cam drive shafts 12, 13 forwardly or backwardly in response to an operation state of the engine for achieving a prescribed object.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a valve opening/closing control device for controlling the opening/closing timing of the intake and exhaust valves of an internal combustion engine to an optimal state depending on the operating condition of the engine. be.

[Conventional technology]

In conventional cam-driven valve train mechanisms, the opening and closing timing of the intake and exhaust valves is fixedly set so that the engine can operate in the optimal state (maximum efficiency) at a specific engine speed and torque, such as at rated output. are doing.

[Problem that the invention seeks to solve]

Therefore, in the above-mentioned valve operating mechanism, when the engine is operated at a low load, exhaust gas blows back and the efficiency of the engine decreases, leading to a worsening of the fuel consumption rate and exhaust components. This problem can be avoided by shortening the overlap period of the intake and exhaust valves, but this will reduce the scavenging efficiency at high loads and high speeds.
This creates a new problem of reducing intake efficiency. For this reason, it has two intake valves, and a cam with a different shape is set for each intake valve.
A method has been proposed in which a switching mechanism is added to operate or stop one of the two valves depending on the high load. However, with this method, an additional intake valve is added, and a cam valve mechanism that drives the valve is also added, and a device to operate the valve mechanism is also required, which means that the existing engine cannot be operated. There is a drawback that structural changes are required not only to the valve mechanism but also to the engine body.

Further, since the opening/closing timing is fixed for the two valves, it is impossible to set the optimal opening/closing timing for all operating conditions.

This invention was created in view of the above problems, and continuously adjusts the optimal opening/closing timing of the intake valve or exhaust valve according to the operating condition of the engine without changing the existing cam and valve drive mechanism. An object of the present invention is to obtain a valve opening/closing control device for an internal combustion engine that can control the valve opening and closing of an internal combustion engine.

[Means for solving problems]

The valve opening/closing control device for an internal combustion engine of the present invention uses rotation of a first rotating shaft that rotates in the same phase as the crankshaft and rotation of a third rotating shaft that is driven by a stepping motor as original motions. A second rotation shaft, which is a cam drive shaft for an intake or exhaust valve, is driven by a differential gear device.

[Effect]

In this invention, the phase of the second rotary shaft is advanced or retarded by manipulating the rotation angle of the stepping motor according to the operating state of the engine, the opening/closing timing of the valve is continuously variably controlled, and In some cases, the valve opening timing is initialized by the initial angle position setting means. 2 is a combustion chamber defined and formed by the cylinder block 1 and piston 3; 4 is a spark plug located at the top of the combustion chamber 2; 5 is an intake pipe 6
An intake valve 7 opens and closes a flow path between the combustion chamber 2 and the combustion chamber 2, and a throttle valve 7 is disposed within the intake pipe 6. Also,
8 is an exhaust valve that opens and closes a flow path between the exhaust pipe 9 and the combustion chamber 2, 10.11 is a cam that drives the intake valve 5 and the exhaust valve 8, respectively, and 12.13 is each of the above-mentioned cams i.
This is the cam drive shaft which is the second rotating shaft that drives the cams.

FIG. 3 shows a configuration in which the cam drive shafts 12 and 13 are driven by the crankshaft of an internal combustion engine. In the figure, 12 and 13 are the cam drive shafts, and 14 is the crankshaft. Numeral 15 is a pulley that rotates together with the crankshaft 14 and drives a timing belt 16. A boo 9-117 is driven by this timing belt 16 and rotates a cam drive shaft. Further, 18 is a pulley attached to the cam drive shaft 12, 19 is a timing belt that drives this pulley 18, and 20 is a differential gear device, which is attached to the first rotating shaft 21 that rotates in the same phase as the crankshaft 14. gear 2
1a and a gear 22a integrally attached to a third rotating shaft 22 driven by a stepping motor 23 whose rotational phase and speed can be controlled by electrical signals from a control circuit 33, which will be described later. The timing belt 19 is configured to drive the timing belt 19 with its slave motion gear.

FIG. 1 shows the details of the configuration of the differential gear device 20, including its surroundings. In the figure, 19 to 23 have the same structure as shown in FIG. 3, so the same reference numerals are given and the explanation thereof will be omitted. A sensor 24 is provided on the outer periphery of a gear 21a that rotates in the same phase as the crankshaft 14, and is used to detect the rotational speed of the crankshaft 14. This sensor is an electromagnetic pickup or the like that electromagnetically detects unevenness of the teeth of the gear. can be used and needed. 25
26 are bevel gears, each rotatable around the central axis 27, and gears 21a and 2 on the outer periphery of each.
A gear that meshes with 2a is formed.

The central shaft 27 is rotatably supported by a bearing 28, and a pinion shaft 29 is fixed so that the axial direction of the pinion shaft 29 can be directly fired. The pinion shaft 29 has this pinion shaft 2.
Small bevel gears 30.31 are mounted which are rotatable about 9, and each small bevel gear 30.31 meshes with the bevel gears 25 and 26. Both ends of the pinion shaft 29 are fixed by pulleys 32 that drive the timing belt 19. 33 is a control circuit that determines the opening timing of the intake valve 5 so as to maximize the efficiency of the engine using parameters indicating the operating state of the engine, such as the rotational speed or the pressure of the intake air-fuel mixture as input information, and controls the stepping motor 23 to open the intake valve 5. It outputs a control signal that sets the rotation angle. 34.35 is the bevel gear 2 which is the initial angle position setting means.
In the rotation limiting member 6, 34 is a protrusion fixed to the bevel gear 26, and 35 is fixed to the cylinder block 1.

Next, the operation of the valve opening/closing control device for an internal combustion engine having the above configuration will be explained. The rotation of the crankshaft 14 is controlled by the gear 21a
, bevel gear 25 , small bevel gear 30 , 31 It is transmitted to the pulley 32 via the pinion shaft 29 . At this time, the bevel gear 26 is held at a fixed position by the stepping motor 23 via the gear 22a so as not to rotate. In this case, if the rotational speed of the bevel gear 25 is n, the pulley 32 rotates in the same direction as the bevel gear 25 at a rotational speed n/2 and with a constant phase relationship. Furthermore, when the stepping motor 23 rotates the bevel gear 26 in the same direction as the bevel gear 25 by a certain angle θ during the above operation, the pulley 32 rotates with a phase advance of θ1/2 from the original phase, and the stepping motor 23 When rotated by θ in the opposite direction, θ is greater than the original phase.
It rotates with a delay of 2/2. Incidentally, in order to maintain the rotation angle position of the stepping motor 23 at a desired position, it is necessary to supply a current of a certain value or more. When the engine is not running, there is usually no current supplied to the stepping motor 23 as described above, so when starting the engine again, the stepping motor 23
The rotational angular position of the bevel gear 26, that is, the angular position of the bevel gear 26 is indefinite. The operation of this embodiment including such a case will be explained with reference to FIGS. 4 and 5.

Fig. 4 is a diagram showing the change in the lift amount of the intake valve 5 with respect to the crank angle, and Fig. 5 is a diagram showing the change in the rotation angle of the stepping motor 230 with respect to the passage of time from the start when the engine is started and a certain operation is performed. These diagrams show changes, and A to D in these diagrams correspond to each other. In Figure 5 (
4) shows the state in which the bevel gear 26 changes from an unstable angular position to its rotation being restricted by the rotation limiting members 34 and 35 immediately after the start of operation. That is, in this period (4), since the control circuit 33 is not supplying a control signal to the stepping motor 23, the holding force of the stepping motor 23 is small, and therefore the bevel gear 26 is moved from the indefinite angular position before starting.
Due to the rotational force of the crankshaft 14, the crankshaft 14 rotates counterclockwise in the drawing via the gear 21a, the bevel gear 25, and the small bevel gears 30 and 31, and this rotation continues until it is restricted by the rotation limiting members 34 and 35. If this limited rotation angle position is taken as an initial value, the intake valve 5 after initial setting starts to open from a phase position of 25 degrees after top dead center, as shown in FIG. 4 (4). After that, the control circuit 33 determines when to start opening and closing the valve according to the operating state, for example, 10 degrees after top dead center.
If you specify the phase position of stepping motor 2
3 rotates the bevel gear 26 by 20 degrees, and the valve timing changes as shown in FIG. 4(C).

Furthermore, the control circuit 33 controls the rotation angle of the stepping motor 23 as shown in FIG.
). The control circuit 33, which performs such operations optimally according to the operating state of the internal combustion engine, is specifically composed of an electronic control circuit such as a microcomputer with memory and calculation functions, and is configured to control the intake valve 5. The opening timing of the engine is determined by a predetermined program based on the input operating parameters or by calculating the optimum value of efficiency based on the output torque of the engine.

In the above embodiment, an example of opening/closing control for the intake valve 5 was shown, but the same is possible for the exhaust valve 8 as well.

〔Effect of the invention〕

As described above, according to the present invention, the second rotary shaft, which is the cam drive shaft, is driven by the differential gear device whose original motion is the third rotary shaft driven by the chipping motor. Because it is configured to drive, there is no need to change the structure of the existing cam and valve mechanism, and the optimal valve opening/closing timing can be continuously controlled over a wide range of engine operating conditions. . Furthermore, since the initial angular position setting means is provided, highly accurate angular setting is possible without feedback regarding the angular position.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are diagrams showing the configuration of main parts of a valve opening/closing control device for an internal combustion engine according to an embodiment of the present invention,
Fig. 2 is a block diagram of the main parts of a general internal combustion engine, Fig. 3 is a block diagram schematically showing an embodiment of the present invention, and Figs. 4 and 5 are operational waveform diagrams of the embodiment device, respectively. It is. 5... Intake valve, 8... Exhaust pal 7", 12.1
3... Second rotating shaft (cam drive shaft), 14... Crankshaft, 20... Differential gear device, 21... First rotating shaft, 22... Third rotating shaft , 2°3...Stepping motor, 33...Control circuit, 34.35...Rotation limiting member. In addition, the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] A first rotating shaft that is driven by the crankshaft of the internal combustion engine and rotates in the same phase as the crankshaft, a second rotating shaft that opens and closes either the intake valve or the exhaust valve, and the operating state of the internal combustion engine. A control circuit that receives a parameter signal indicating the internal combustion engine as input and outputs a predetermined control signal according to the operating state of the internal combustion engine, and is driven in forward and reverse rotation by a stepping motor that is controlled by the control signal output by this control circuit. a third rotating shaft driven by the stepping motor; a differential gear device in which the rotation of the first and third rotating shafts is the original motion and the rotation of the second rotating shaft is output as the slave motion; 3. A valve opening/closing control device for an internal combustion engine, comprising initial angular position setting means for setting a reference position for operating the rotation angle of the rotating shaft.