JPS6036705A - Valve timing controlling apparatus for engine - Google Patents

Abstract

PURPOSE:To obtain a high charging efficiency separately for each engine and according to the atmospheric conditions at all times, by controlling the valve closing timing of an intake valve in response to the pressure at an intake port. CONSTITUTION:Operational conditions of an engine are detected by an engine- speed sensor 18, a crank-angle sensor, a throttle-opening sensor 13, etc., and the valve opening and closing timing of an intake valve 6 is controlled according to the operational conditions of the engine. Further, a pressure sensor 12 is attached to an intake port 4', and the valve closing timing of the intake valve 6 is corrected in response to the pressure at the intake port 4'. Thus, since the inertia of intake air is utilized effectively, the charging efficiency of the engine is raised. Further, even if the optimum valve closing timing of the intake valve for a plurality of engines differs from each other or it is varied according to the atmospheric conditions or the like, the optimum valve closing timing is corrected on the basis of the actual pressure at the intake port, so that an optimum valve closing timing can be obtained under any circumstances.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a control device for controlling engine valve timing, particularly the closing timing of an intake valve.

(Prior art) Generally, the opening/closing timing of the intake and exhaust valves of an engine is uniquely set by the profile of a cam that is rotationally driven in synchronization with the rotation of the crankshaft. In order to improve performance, it is desirable to variably control these timings depending on the operating conditions. For example, regarding the closing timing of the intake valve, at high speeds it is desirable to delay the closing timing and maximize the intake inertia to increase the intake air filling amount, and at low speeds, if the closing timing is too late, the intake valve closing timing is delayed. It is desirable to reduce the amount of delay since the blowback occurs.

As an example of a device for variable control of valve timing, there is an invention related to a variable timing valve lifter device disclosed in Japanese Patent Publication No. 1847-1847. A valve lifter with a variable effective length is interposed between the interlocking bushing rod, and at low speeds, the effective length of the lifter is shortened so that the valve opens later than the timing determined by the cam profile and closes earlier. Furthermore, at high speeds, the effective length is lengthened to control the opening/closing timing of the valve to the timing determined by the cam profile.

However, as mentioned above, the optimal opening and closing timing of the cam changes depending on the engine operating conditions (rotation speed and load).
), but especially the intake tt! The optimum closing timing of the intake valve in order to improve the filling efficiency to the limit by utilizing the l property varies slightly depending on outside air conditions such as outside air). Furthermore, even if the engine is of the same model, the optimum timing may differ slightly from engine to engine due to variations in the dimensions of each part.

(Object of the Invention) The present invention is intended to deal with the above-mentioned actual situation regarding engine valve timing, and in particular, in addition to controlling the closing timing of the intake valve according to the operating state of the engine, it also provides correction control. As a result, each engine has different outside air conditions.1. [Also, the timing is optimal for this purpose. The purpose of this is to improve the -L engine output by increasing the intake valve [fi as much as possible, especially at high loads.

-3- (Structure of the invention) The engine valve timing control device according to the present invention includes:
In order to achieve the above objectives, it is structured as follows.

That is, as shown in FIG. 1, the output of the operating state detection means A that detects the engine rotational speed, load, etc. is received by the intake valve closing timing adjusting means B. It operates to adjust the timing to correspond to the operating condition at the time of A. On the other hand, in the vicinity of the above-mentioned intake valve C in the intake bow 1-D, there is provided a pressure sensor for detecting the pressure on the bow 1, and in response to a signal from the sensor F, a valve closing timing correction means is provided. The closing timing of the intake valve C, which is adjusted by the adjustment means B, is corrected to match the change in pressure.

By the way, the boat pressure above shows a peak at the end of the intake stroke, but if the intake valve close timing is too early, the peak value will occur after the valve closes, and if the closing timing is too early, the peak value will occur after the valve closes. occur before. This peak value controls the action of pushing the intake air into the combustion chamber at the end of the intake stroke, and when this peak value passes, the intake air begins to blow back, so the intake valve is operated near the time when the peak value occurs. It is most preferable to close the valve at 200 mm to increase filling efficiency. In that case, the peak value depends on the variation of each engine, or
The timing of occurrence varies depending on outside air conditions, etc., but the boat pressure is detected by the pressure sensor F, and the opening timing of the intake valve C is corrected to match this pressure change l)+
This period is always considered to be the optimal timing for increasing filling efficiency.

(Example) The present invention will be explained below with reference to embodiments shown in the drawings.

As shown in FIG. 2, the engine 1 has an intake passage 4 leading from the air cleaner 2 to the combustion chamber 3, and an exhaust passage 5 leading from the combustion chamber 3 to the outside. An intake valve 6 and an exhaust valve 7 are provided at the openings of the combustion chamber 3, and a spark plug 8 is installed in the combustion chamber 3.

-5- There is one aflow meter 9 in the intake passage 4 from the air cleaner 2 side. A throttle valve 10 and a fuel Y1 nozzle valve 11 are provided, and a pressure sensor 12 for detecting boat pressure is installed in the intake boat 4' near the intake valve 6 in the intake passage 4. Further, the throttle valve 10 is provided with a throttle distance sensor 13.

On the other hand, the intake valve 6 is opened and closed by an intake cam 15 rotationally driven by a crankshaft 14, and the intake cam 15 is provided with a profile variable mechanism 17 operated by an actuator 16. There is. Then, a signal S1 from the engine rotation speed sensor 18 that detects the rotation speed of the engine 1, a signal @S2 from the throttle speed sensor 13, a signal S3 from the pressure sensor 12, and a signal S3 from the pressure sensor 12, A control circuit 20 is provided which receives a signal @S4 from a crank angle sensor 19 that detects the rotation angle of the shaft 14, and the acticoator 16 is operated in accordance with a control signal So output from the circuit 20. It's becoming a sea urchin.

-6- Next, to explain the specific structure of the intake cam 15 and the variable profile mechanism 17, as shown in FIG.
The camshaft 21 is rotatably supported by the camshaft 21 via a bearing member 23.
A piston 25 fitted in the cylinder 24 is provided at one end.
is fixed. The piston 25 or the camshaft 21 is biased rightward in the drawing by a spring 26, and in response to the fluid pressure Po introduced into the cylinder 24 from the control valve 27 via the fluid passage 28. It is designed to be slid to the left in the drawing against the spring 26.

The control valve 27 is connected to the pump 29 at a
and the fluid passage 28 through an orifice 31, a drain passage 33 branched from the main passage 32, and a needle 34 for adjusting the opening degree of the drain passage 33. The needle 34 is moved by the actuator 16 to adjust the fluid pressure Po introduced into the cylinder 24.

Here, the actuator 16 moves the needle 34 in response to the control signal So input from the control circuit 20 to adjust the fluid pressure Po, and the piston 25 or the camshaft 21 slides in response to the fluid pressure Po. Because I do,
The camshaft 21 slides in response to the control signal So.

The tip of the valve stem of the intake valve 6 is always in contact with the intake cam 15 located on the camshaft 21 by a spring 35, so that the rotation of the cam 15 drives the intake valve 6 to open and close. However, this cam 15 is a three-dimensional cam whose profile changes along the axial direction. That is, as shown in FIG. 4(a), if we take three cross sections II, Ir-IT, and In-III in the axial direction and compare the filters in each cross section, As shown in (b), in all cross sections, the point a where the lift amount rises from zero with respect to rotation in the X direction is the same, but the points c, d, where the lift amount returns to zero again are 8- The right side of the cam 15 is located at the rear with respect to the rotational direction X. Therefore, as shown in FIG. 3, the camshaft 21 slides to the left from the state in which the intake valve 6 is in contact with the left side of the cam 15, and the contact position of the cam 15 and the valve 6 is relative to each other. As the valve 6 moves to the right, the closing timing of the valve 6 gradually becomes later.

Next, the operation of the above embodiment will be explained.

The J control circuit 20 shown in FIG. 2 is constituted by, for example, a micro combi coater, and operates according to the flowchart shown in FIG. That is, the control circuit 20 first detects the engine speed and throttle opening based on the signals -81 and S2 from the engine speed sensor 18 and the throttle opening sensor 13 in steps 01 to Q3, and detects the engine speed and throttle opening according to these values. As shown in FIG. 6, the engine operating range n1. n2. Determine... Then, in step Q4, the control value θ0 (for example, the rotation angle of the crankshaft from the intake bottom dead center) -〇 - of the intake valve closing timing, which is stored in advance and corresponds to the operating region at that time, is read, and in step Q5 A control signal So corresponding to the control value θ0 is output to the actuator 16 of the cam profile variable mechanism 17.

The actuator 16 receives the input control signal S.

By moving the needle 34 of the control valve 27 in accordance with the control signal So, a fluid pressure Po corresponding to the control signal So is generated, and the intake cam 15 is moved in the axial direction together with the camshaft 21 in accordance with this fluid pressure Po. Ru. As a result, the closing timing of the intake valve 6 is set to the above ff1i fill value θ0 corresponding to the engine speed and throttle opening at that time.
It is said that

In this way, when the engine speed is high under high load, for example, the intake cam 15 is moved to the left in FIG. 3, and the closing timing of the intake valve 6 is delayed, thereby improving the filling efficiency. On the other hand, at low speeds, the intake cam 15 is positioned to the right as shown in FIG. 3, and the closing timing of the intake valve 6 is made relatively early, thereby preventing intake air from blowing back.

The control circuit 20 performs the basic control of the closing timing of the intake valve 6 corresponding to the engine operating condition as described above, and also performs correction control as follows in steps 06 and below. That is, first, in step Q6, a temporary crank angle θp at which the pressure in the intake boat 4' reaches a peak value is detected based on the signal S3 from the pressure sensor (J12) and the signal RS4 from the crank angle sensor (J19). Ru.

By the way, as shown in Fig. 7, the pressure 1~resistance temporarily becomes tenacous due to the residual pressure in the combustion chamber 3 immediately after the intake valve 6 asks, and then the negative pressure value increases as the piston descends. Then, around the time when the intake valve 6 closes, a peak occurs again at "-4". At this time, if the intake valve 6 closes while the intake flow passing through the intake boat 4' maintains sufficient momentum, the curve (A) in Fig. 7 (I) indicates J: Sea urchin boat pressure. The peak of the intake valve 6 occurs after the valve 6 is closed, and the peak of the intake valve 6 occurs after the intake flow declines.
When the valve 6 is closed, a peak occurs before the valve 6 closes, as shown by curve (b). In the former case, the closing timing of the intake valve 6 is too short and the intake inertia is not fully utilized, and in the latter case, there is a possibility that intake air blowback may occur. In case,
In either case, this is an undesirable state for improving filling efficiency.

Therefore, the control circuit 20 controls the baud 1 to baud in step Q6 above.
When the crank angle 0p when the pressure shows the peak value is detected, in step Q7, the crank angle θp is compared with the control value θ0 according to the basic control described above, and the difference between 1 and 2 is determined by the set value (for example, ± at the crank angle). 206) When ε or more, θ0>θ
If ρ, step Q8. Q9 sets the control value Oo to 00-α
〈α: predetermined correction value) and 0 (, If < θp, the control value θo @ Do 1 α
Correct to. In other words, by bringing the control value θ0 closer to the crank angle θp at which the peak value of boat pressure occurs,
In the next cycle, when outputting the control signal So in step Q5, the control signal So corresponding to the control value Qo corrected in 1] as described above is output.

As a result, the closing timing of the intake valve 6 is controlled to be near the timing when the peak value of the boat pressure occurs. As shown in c), when the timing when the intake valve 6 closes and the timing when the boat pressure reaches its maximum are approximately coincident, and this pressure forces the intake air into the combustion chamber 3 for 1 no. The intake valve 6 will be closed. In this way, the filling efficiency of the intake air is maximized in the range of 4 possible.
will be done.

(Effects of the Invention) According to the present invention, in the valve timing control device in which the closing timing of the intake valve is variable controlled 11 times according to the operating condition of the engine, the intake valve Further, the valve opening timing is corrected and controlled to the optimum timing in accordance with changes in the FF force within the intake boat. As a result, the intake air filling efficiency is made as high as possible, especially during high loads where high output is required, and the required output can be obtained. In particular, according to the present invention, even if the optimal intake valve closing timing differs from engine to engine or changes depending on outside air conditions, etc., the above correction control is performed according to the actual boat pressure, so it is always at the optimum closing timing. The opening timing of the intake valve is obtained = 13
-

Regarding the opening/closing timing of the intake valve, it is desirable to not only delay the valve closing timing at high speeds, but also to open the valves earlier than at low speeds. Therefore, in the present invention, the valve opening timings are also controlled at the same time. But J: No.

In addition, the valve closing time II f; It is also possible to adopt a configuration in which the adjustment is made manually.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of the present invention, FIG. 2 is a control system diagram showing an embodiment of the present invention, FIG. 3 is a longitudinal sectional view showing the configuration of the intake cam profile variable mechanism in the embodiment, and FIG.
Figures (a) and (b) are side and front views showing the external shape and profile of the intake cam, Figure 5 is a flow chart diagram showing the operation of this embodiment, and Figure 6 is stored in the control circuit of this embodiment. FIGS. 7(a) and 7(b) are a valve timing diagram and a pressure change characteristic diagram showing the operation of the 14th embodiment. A... Operating state detection means, B... Valve closing timing adjustment means, C... Intake valve, D... Intake port, E...
Pressure lens, F... +111 correction means when valve is closed, 1...
- Engine, 4'... Intake boat, 6... Intake valve, 12... Pressure sensor, 13... Throttle opening sensor, 15... Intake cam, 16... Acticoator, 17...・Profile variable mechanism, 18...Engine speed sensor, 1...Crank angle sensor, 20
... Control circuit applicant: Toyo Kogyo Co., Ltd. = 15 - Figure 1 ← Sorotoyo Yabuguchi + Kai - L Higashiya Ichino -

Claims (1)

[Claims] (1) A valve closing timing adjusting means for adjusting the opening timing of the intake valve according to the operating condition of the engine, and a valve closing timing adjusting means installed in the vicinity of the above-mentioned intake valve in the intake boat to detect the pressure from port 1 to Valve timing control for an engine, comprising: a pressure sensor; and valve-closing timing correction means that receives a signal from the pressure sensor and corrects the closing timing of the intake valve to match changes in boat pressure. Device.