JPS59119008A - Suction and exhaust valve lift control device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To precisely control the lifts of suction and exhaust valves by a method wherein actual values are approached to the target value by feedback control in a device, in which the lifts of suction and exhaust valves are variably controlled by means of a hydraulic gear. CONSTITUTION:The lifts of suction and exhaust valves 1 are controlled by changing the location of the support of a rocker arm 3 in response to the running conditions of an engine by means of a hydraulic gear. The valve lift is detected at the location of a lifter 10 by a sensor 13 and compared with the target value calculated based upon the various running conditions of the engine by means of a microcomputer 17 so that a rack 12 is driven in order to control the location of the lifter 10 so as to nullify the deviation between the target value and the actual value of the valve 1. The decision of the result of comparison between the detected value and the target value is performed every lapse of the oil pressure response lag of the drive gear, resulting in enabling to control the lift highly accurately and consequently contriving to increase the output and to improve the fuel consumption of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for variably controlling the lift amount of intake and exhaust valves of an internal combustion engine.

Conventional valve mechanisms that open and close intake and exhaust valves in synchronization with engine rotation, for example in the case of O, H, C, (overhead cam) engines, operate the rotational movement of the crankshaft via a timing gear or timing belt. After being transmitted to the camshaft, the rotational motion of the camshaft is transmitted to one end of the rocker arm, and by swinging the rocker arm around the rocker shaft, the intake and exhaust valves engaged with the other end are opened and closed.

By the way, in such a conventional general valve train, the lift amount of the intake and exhaust valves is constant and is set according to the medium speed rotation range of the engine, so there are the following problems. Ta. In other words, in the low speed rotation region of the engine, the intake inertia is small, so the pumping loss of intake air due to intake air leaking into the intake passage from the gap between the intake valve and the intake port, which is not yet fully closed at the beginning of the compression stroke, is large and the intake filling efficiency is reduced. This caused a drop in output. Conversely, in the high-speed rotation range, the intake inertia increases, so it is desired to increase the intake air filling efficiency by utilizing the action of pushing the intake air into the combustion chamber near the end of the intake stroke. In terms of volume, the valve closes early and the opening area is small, making it impossible to fully utilize the intake inertia.In addition, the flow velocity of the intake air also increases, which increases the throttle resistance at the intake port throughout the intake stroke, which reduces the intake air filling efficiency. was decreasing. Furthermore, in the high-speed rotation range, the lift amount of conventional exhaust valves was insufficient to increase the scavenging efficiency due to inertia.

Furthermore, if the overlap period is increased by increasing the ref1 amount of the intake and exhaust valves, so-called self-EGR occurs, in which the exhaust gas recirculates into the combustion chamber at the beginning of the intake stroke, but in the low-speed range where the exhaust inertia is small, the amount of EGR decreases. This caused combustion to become unstable.

In order to solve these problems, we have conventionally detected the engine operating state by changing the lift amount of the intake and exhaust valves and the fulcrum position of the rocker arm using a hydraulic drive device.
A method that performs variable control according to the detection result has also been proposed.

However, this type of conventional system does not have an effective means to correct any discrepancy between the actual intake/exhaust valve lift amount of the hydraulic drive system and the target value, so it cannot be used with high accuracy. Lift amount control could not be performed.

The present invention was developed in view of these conventional problems.The present invention detects the actual lift amount of the intake/exhaust valve, and determines the actual lift amount based on the actual lift amount and the detection results of other engine operating conditions. Comparing and determining the lift amount with the target value, the hydraulic drive device is driven and corrected so that the actual lift amount approaches the target value, and the actual lift amount and the target value are compared and determined based on the hydraulic response delay time elapsed. By controlling the lift amount with high accuracy, the suction and
An object of the present invention is to provide an exhaust valve lift amount control device.

The present invention will be described below based on an embodiment shown in FIGS. 1 to 4. In the following explanation, since the lift amounts of the intake valve and the exhaust valve are controlled separately, these control means are provided separately, but for the sake of simplicity, the intake and exhaust valves will be explained together.

In FIG. 1, intake and exhaust valves 1 of an internal combustion engine are each urged to close by a valve spring 2, and a base end engages with one end of a rocker arm 3. As shown in FIG. The other end of this rocker arm 3 is in contact engagement with a cam 5 of a camshaft 4 that rotates in synchronization with engine rotation. Further, the rocker arm 3 is swingably supported by a rocker shaft 6 at the center thereof, and as the cam 5 rotates, the rocker arm 3 swings around the rocker shaft 6 and engages one end thereof. The exhaust valve 1 is opened and closed.

In addition, a valve lifter 7 is provided with one end rotatably attached to the engine body, and a U-shaped groove 8 is formed approximately in the middle of the valve lifter 7.
The rocker shaft 6 is engaged within the spring 9 via the spring 9. Further, a hydraulic lifter 10 is attached to the other end of the valve lifter 7.
By contacting and engaging the lower end surfaces of the valve lifter 7 and changing its protrusion amount, the swinging position of the valve lifter 7 is changed, thereby changing the position of the center lift 6 of the rotor, thereby controlling the lift amount of the intake/exhaust valve 1. There is. A control rack 12, which is moved by the electromagnetic force of a linear solenoid 11, is engaged with the hydraulic rack 10, and by controlling its rank position, the amount of oil injected is changed, and the amount of protrusion of the lower end of the hydraulic lifter 10 is controlled. Further, a lid position sensor 13 for detecting the lift amount of the intake/exhaust valve 1 based on the position of the valve lifter 10 and a rank position sensor 14 for detecting the position of the control rack 12 are provided.
Based on the signal from the intake/exhaust valve 1 as shown below
control the amount of lift. That is, FIG. 2 shows the configuration of the control circuit, in which the ignition signal as the engine rotational speed signal is waveform-shaped by the waveform shaping circuit 15 and then sent to the rack position sensor 1.
The rack position signal from 4, the lid position signal from the lifter position sensor 13, and the accelerator opening signal detected by the accelerator opening sensor (not shown) are sent to A/D converter 16.
/D converted and then input to the microcomputer 17.

The control operation of the microcomputer 17 will be explained with reference to the flowchart in FIG. 3 and the time chart in FIG. 4.

A memory (not shown) of the microcomputer 17 stores lift amounts and corresponding rank position target values according to engine operating conditions such as engine speed and accelerator opening. The difference ΔL between the target value of the lift amount read from the memory based on signals such as the accelerator opening degree and the actual lift amount based on the lid position signal is determined (Slap 1). Next, according to this ΔL, the target value to be corrected for the control rack 12 is read from the memory, compared with the current rank position detected by the rank position sensor 14, and a correction signal is output to the linear solenoid 11 to control the The rack 12 is driven and corrected to the target position (slump 2).

Next, when the control rack 12 is moved by the correction control and the actual rank position detected by the rack position sensor 14 reaches the vicinity of the target value of the rack position read from the memory, the hydraulic pressure by the correction control is The hydraulic response delay time of the lifter 10 is determined as a function of ΔL, Ne (engine speed), and T (engine load such as throttle valve opening) (this is also read from the memory in advance), and this is calculated from that point. The wait time Td is set until the next time the lift amount is detected by the lid position sensor 13 (step 3). That is, in step 3, the comparison between the actual lift amount and the target value is performed at the stage when the previous lift amount correction control is completed, taking into account the hydraulic pressure delay time of the hydraulic lifter. The occurrence of hunting based on the determination can be prevented, and the lift I can be corrected and controlled stably and with high precision.

By controlling the lift amounts of the intake and exhaust valves 1 with high precision in this manner, it is possible to increase the intake air filling efficiency over the entire operating range of the engine, and to obtain stable combustion performance by adjusting the self-EGR. This is possible. Note that 18 is a drive circuit for the linear solenoid II.

As explained above, according to the present invention, in a device that variably controls the lift amount of an intake/exhaust valve using a hydraulic drive device, the difference between the control target value of the lift amount and the actual lift amount is compared and determined, and the two are brought closer together. Feedback control is performed in this manner, and the comparison judgment is performed every time the hydraulic response delay time of the hydraulic drive device elapses, so it is possible to detect the lift amount with high accuracy, thereby increasing the output by improving the intake air filling efficiency.
It is possible to improve engine operating performance as much as possible, such as improving fuel efficiency, stabilizing combustibility by adjusting self-EGR, and improving exhaust characteristics.

[Brief explanation of drawings]

1 to 4 show an embodiment of the present invention, FIG. 1 is a schematic diagram of a variable lift amount control device, FIG. 2 is a control circuit diagram, FIG. 3 is a flowchart, and FIG. 4 is a time chart. It is. 1... Intake/exhaust valve 3... Rocker arm 6.
...Rocker shaft 7...Valve lifter lO...
・Hydraulic lifter 11...Linear solenoid 12...
・Control rack 13...Rack position sensor 14...Rack position sensor 17...Microcomputer patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Fujio Sasashima

Claims (1)

[Claims] Intake/exhaust valve reflux control for internal combustion engines that variably controls the lift amount of the intake/exhaust valves by variably controlling the fulcrum position of the rocker arm for opening/closing the intake/exhaust valves using a hydraulic drive device depending on the operating state of the engine. In the device, a lift amount detection means for detecting the lift amount of the intake/exhaust valve, and a detection signal from the lift amount detection means and other detection means for detecting the engine operating state are inputted and an actual lift amount detection value is obtained. The lift amount is determined by comparing the set lift amount target value based on the detection results of other engine operating conditions, and drives the hydraulic drive device to correct the stiffness lift amount so that the actual lift amount approaches the target value. An internal combustion engine characterized in that it is provided with a correction means and a judgment timing control means for operating a comparison judgment between an actual lift amount detection value by the correction means and a target value every time the hydraulic response delay time of the drive device elapses. intake/exhaust valve lift control device.