JPH089385Y2 - Engine intake timing control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to control of valve timing in an engine.

(Prior Art) The timing of opening and closing intake / exhaust valves in an engine, that is, the valve timing, is set to an optimum value in a predetermined operating state according to required operating performance such as fuel consumption and output
Usually, the set conditions are fixed, but in that case, it is inevitable that the operating performance is deteriorated because the optimum valve timing is not obtained in the region outside the set conditions. Therefore, as is well known, there has been conventionally proposed a system in which the valve timing of the engine is variable according to the engine speed and the load. According to this variable valve timing system, the opening / closing timing of the intake / exhaust valve or the valve overlap amount can be changed to an optimum value according to the operating state, and the operating performance can be improved over a wide operating range. it can. For example, when the engine output is important, the closing timing of the intake valve is early, that is,
By reducing the crank angle from when the piston sucking intake air into the cylinder passes through the bottom dead center until the intake valve is closed, it is possible to prevent the intake air from being blown back at low speed and improve the engine output. Further, by delaying the closing timing of the intake valve to some extent at the time of high rotation, it is possible to improve the charging efficiency and the output by the inertial effect of intake air. On the other hand, when importance is attached to fuel consumption, the intake valve closing timing is delayed at low rotation speed and low load to increase the required throttle opening for the required output, reduce pumping loss, and improve fuel consumption.

In this way, the control that makes the intake valve closing timing faster or slower depending on the operating state is
For example, it is disclosed in JP-A-60-119325.

(Problems to be solved by the invention) By the way, for example, when trying to reduce the pumping loss and improve fuel efficiency by delaying the closing timing of the intake valve at the time of low rotation and low load as described above, Vehicles equipped with the engine set to the timing,
When traveling in the lowlands, which is the standard state, the desired fuel efficiency is obtained, and the reduction in output at that time is not a problem, but when traveling in the highlands, the intake pressure is reduced due to the decrease in atmospheric pressure. Therefore, if the timing of closing the intake valve is the same, the influence of the output decrease becomes large, and the compression pressure becomes too low, which causes deterioration of combustion.

The present invention has been made in view of the above problems,
The purpose is to compensate for a decrease in intake air charge amount due to a change in atmospheric pressure, to secure engine output, and to prevent deterioration of drivability.

(Means for Solving the Problem) The present invention focuses on the fact that it is possible to correct the decrease of the intake charge amount due to the change of the atmospheric pressure by changing the closing timing of the intake valve according to the atmospheric pressure. The device is configured as follows. That is, as shown in FIG. 1, the intake timing control device for an engine according to the present invention receives atmospheric pressure detecting means for detecting atmospheric pressure and the output of the atmospheric pressure detecting means. And a variable valve timing mechanism for adjusting the phase of the intake camshaft so as to close the intake valve at the timing set by the valve timing setting means. Is characterized by.

(Operation) The closing timing of the intake valve is set to the advancing side as the atmospheric pressure is lower according to the atmospheric pressure, and the intake valve is opened / closed at the valve timing thus set. As a result, in the lowland, which is the standard state, the timing of closing the intake valve becomes relatively late, and the throttle is opened accordingly, and the effect of improving fuel efficiency by reducing pumping loss becomes remarkable. In high altitudes where atmospheric pressure is low,
The timing of closing the intake valve is relatively early, which compensates for the decrease in intake charge.

(Example) Hereinafter, an example will be described with reference to the drawings.

FIG. 2 is an overall system diagram of an embodiment of the present invention.
In this embodiment, an intake port 3 and an exhaust port 4 are opened in the combustion chamber 2 of the engine 1, and an intake valve 5 and an exhaust valve 6 are provided in the openings of the intake port 3 and the exhaust port 4, respectively. . And intake port 3
A surge tank 8 is formed in the upstream intake passage 7, and a throttle valve 9 is provided upstream of the surge tank 8. An injector 10 for injecting fuel toward the intake port 3 is provided downstream of the intake passage 7, and an air flow meter 11 for detecting the intake air amount is provided upstream of the intake passage 7, and The upstream side is connected to an air cleaner (not shown). When the piston 12 of the engine 1 operates, the air that has passed through the air cleaner is introduced into the intake passage 7 as shown by the arrow in the figure, and is sucked into the combustion chamber 2 via the intake valve 5. At that time, the amount of air taken in is controlled by the throttle valve 9. Further, the fuel injection amount is calculated in a known manner using the intake air amount and the engine speed as basic parameters, and the fuel is injected from the injector 10.

In the engine 1, a variable valve timing mechanism 14 of a helical spline type, which is known per se, is provided between the cam shaft 13 that drives the intake valve 5 and the drive pulley thereof. This variable valve timing mechanism
14 is controlled by the control unit 15.

An output signal of a rotation sensor 16 for detecting engine rotation and an intake air amount signal from the air flow meter 11 are input to the control unit 15. Also, an atmospheric pressure sensor 17 is provided, and its detection signal is a control unit.
Entered in 15. And the control unit 15
The engine speed (N) is calculated from the output of the rotation sensor 16, the fuel injection pulse width (T _p ), that is, the engine load is calculated from the engine speed (N) and the output of the air flow meter 11, and these N and As a function of T _p , a basic value of a crank angle (hereinafter referred to as an IC angle) from when the bottom dead center is passed to when the intake valve 5 is closed is calculated, and the IC angle is further corrected according to the atmospheric pressure. . here,
To correct the IC angle, multiply the ratio of the detected atmospheric pressure and the atmospheric pressure in the standard state (760 mmHg) by a constant K
This is done by multiplying the IC angle. Then, a control signal corresponding to the IC angle set in this way is output to the variable valve timing mechanism 14, and the phase of the camshaft 13 that drives the intake valve 5 is adjusted.

FIG. 3 shows the basic characteristics of the IC angle control in this embodiment with the engine speed (N) as the horizontal axis and the load (fuel injection pulse width: T _p ) as the vertical axis. As shown in this figure, in the low rotation / low load region where fuel economy is more important than output, the IC angle is increased, that is, the IC is retarded to delay the intake valve closing timing and reduce pumping loss. In addition, in the high rotation and high load areas where high output is required, the IC angle is made smaller (the amount of retard angle is suppressed) in order to reduce blowback. In the figure, a ₁ , a ₂ ,
The curves indicated by a ₃ and a ₄ are equal throttle opening curves in the standard state (lowland: 760 mmHg) when the IC angle is delayed as described above, of which a ₄ indicates when the throttle is fully open.
Also, the thick solid line (b) shows the throttle fully open in the standard state when the IC retardation is not performed as described above, and the dotted line (c) also shows the equal throttle full opening at high altitude when the IC retardation is not performed. An example of a curve is shown. Here, in the standard state, as shown in the figure with the throttle fully open as an example, the IC retards to T _P and reduces the output by Δ ₁ minute (however, the rotation speed is constant), but in the standard state However, since the output itself is large, this reduction does not matter.
However, at high altitudes, the intake charge amount decreases and the output itself decreases. Therefore, if the IC delay amount is the same, the output will decrease by Δ ₂ minutes as shown in the figure, and the drivability will deteriorate. There is a fear. Originally, the pumping loss is small in the highlands because the atmospheric pressure is low, and therefore it is not necessary to perform the IC retardation at the same level as in the lowlands. Therefore, the above correction is performed so that the IC angle set with the lowland as a standard is made smaller in the highland. FIG. 3 illustrates the correction characteristic.

Next, the above control of this embodiment will be described with reference to the flowchart of FIG.

When starting, first, the engine speed (N) is read. Then, the output of the air flow meter (AFM) is read, and then the fuel injection pulse width (T _p ) is calculated.

The IC angle is then determined from the map as a function of T _p and N.

Next, the atmospheric pressure is read and corrected for atmospheric pressure to obtain the final IC angle.

(Effect of the Invention) Since the present invention is configured as described above, it is possible to reduce the pumping loss of the engine by compensating for the decrease of the intake charge amount due to the change of the atmospheric pressure by controlling the intake timing.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of the present invention, FIG. 2 is an overall system diagram of an embodiment of the present invention, FIGS. 3 and 4 are characteristic diagrams of the same embodiment, and FIG. 5 is control of the same embodiment. It is a flowchart which performs. 1: Engine, 5: Intake valve, 11: Air flow meter, 13: Camshaft, 14: Variable valve timing mechanism, 15: Control unit, 16: Rotation sensor, 17: Atmospheric pressure sensor.
16: rotation sensor, 17: atmospheric pressure sensor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Arakawa 3-3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) References JP 59-162312 (JP, A) JP 58- 25538 (JP, A) JP-A-2-104946 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. An atmospheric pressure detecting means for detecting atmospheric pressure, a valve timing setting means for receiving the output of the atmospheric pressure detecting means, and setting the closing timing of the intake valve to the advanced side as the atmospheric pressure becomes lower, and the valve. An intake timing control device for an engine, comprising: a variable valve timing mechanism that adjusts a phase of an intake camshaft so that an intake valve is closed at a timing set by a timing setting means.