JPH033931A - Throttle valve control means of engine - Google Patents

Abstract

PURPOSE:To finely improve combustibility and fuel consumption performance by setting the opening of a downstream side throttle valve lower than an upstream side throttle valve at the low load operation range, and by setting the opening of the upstream side lower than the downstream side at the high load operation range. CONSTITUTION:At combustion chambers 2 of a four-cycle engine 1, intake ports 3 and exhaust ports 4 are formed, respectively. The respective intake ports 3 are connected to a surge tank 6 through stand-alone intake passages 5, and a main intake passage 7 is connected to the upstream side. An upstream side throttle valve 8 is provided, which is supported with a valve shaft 11 at the main intake passage 7, and downstream side throttle valves 9 are provided at the stand-alone passages, respectively and interlocked with a common valve driving shaft 12. The throttle valves 9 and the throttle valves 8 are respectively connected at the low load and at the high load by a link mechanism 20 which decreases the openings. An EGR is controlled at the low load so as to improve combustibility, and pumping loss is lowered so as to improve fuel consumption at the high load.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a throttle valve control means for an engine having two throttle valves disposed in an intake passage one behind the other in the intake air flow direction.

(Conventional technology) Conventionally, in automotive engines, especially multi-cylinder engines, the Sarno tank Attempts have been made to provide throttle valves on the upstream and downstream sides of the
(See No. 3) (Problem to be Solved by the Invention) By the way, in general, in an engine, the opening periods of the intake valve and the exhaust valve overlap. Therefore, during this overlap period, exhaust gas from the exhaust passage side flows back to the intake passage side, resulting in an increase in internal EGR (exhaust gas directly introduced into the combustion chamber from the exhaust passage side). Become.

However, in a low load range of the engine, the amount of intake air itself is small, so if internal EGR increases, combustibility deteriorates, and response performance deteriorates, which is not preferable.

On the other hand, in the high load range of the engine, the amount of intake air is large and the combustibility itself is maintained relatively well even if the internal EGR increases. There is a need for engine control that focuses on reducing pumping losses and improving fuel efficiency.

As described above, the demand for internal EGR changes depending on the engine load condition, and therefore, in order to improve the overall engine performance, it is necessary to control internal EGR in accordance with the engine load.

However, from this perspective, internal EGR
No attempt has been made to actively control this, and technological development in this regard is required.

Therefore, the present invention reduces the internal EGR caused by the overlap in the opening periods of the intake valve and exhaust valve to the engine load by effectively utilizing the characteristics of the intake system that has two upper and lower throttle valves in the intake passage. It is an object of the present invention to provide an engine throttle valve control means that can control the throttle valve accordingly, thereby improving response performance in a low load range and improving fuel efficiency in a high load range.

(Means for Solving the Problems) In the present invention, as specific means for solving the problems, (1) In the invention set forth in claim 1, the intake passage communicating with the combustion chamber of the engine has an intake upstream side. In an engine that is provided with an upstream throttle valve located on the upstream side and a downstream throttle valve located on the downstream side, the upstream throttle valve and the downstream throttle valve are operated in conjunction with accelerator operation. In the load operation range, the opening degree of the downstream throttle valve is lower than the opening degree of the upstream throttle valve, and in the high load operation area where the valve opening is large, the opening degree of the upstream throttle valve is lower than the opening degree of the upstream throttle valve. (2) The invention according to claim 2 is characterized in that the opening degree is lower than that of the throttle valve. The invention described above is characterized in that the upstream throttle valve is configured to be fixedly held at a predetermined opening in a low load range.

(Function) In the present invention, the following effects can be obtained by having such a configuration.

(1) In the invention described in claim 1, the intake air amount is controlled by the downstream throttle valve in the low load range, and the intake air amount is controlled by the upstream throttle valve in the high load range.

In this case, the pressure within the intake passage is approximately atmospheric between the time when the intake valve was previously closed and the time when the intake valve is opened this time.

Furthermore, in the low load range, the pressure of exhaust gas is almost atmospheric pressure.

Therefore, when the intake air amount is controlled by the downstream throttle valve in the low load range, even if the intake and exhaust valves overlap, the intake pressure and exhaust pressure are almost balanced, so The inflow of internal EGR is suppressed as much as possible, and combustibility is maintained satisfactorily.

On the other hand, when the intake air amount is controlled by an upstream throttle valve in a high load range, the intake pressure in the intake passage downstream of the upstream throttle valve becomes negative pressure, while the exhaust pressure is higher than atmospheric pressure. Therefore, when the intake and exhaust valves overlap, a relatively large amount of exhaust gas flows into the combustion chamber. Therefore, during the intake stroke,
If the total intake air amount to the combustion chamber is constant, the amount of air introduced into the combustion chamber while being throttled by the downstream throttle valve will be reduced by the amount of internal EGR introduced into the combustion chamber at the time of overlap; Bumping loss will be reduced.

(2) In the invention set forth in claim 2, in addition to the effect described in (1) above, the upstream slow/torque valve is maintained at a predetermined opening in the low load range, so that the throttle valve opens as the downstream throttle valve opens. Even if the amount of air introduced into the combustion chamber via the downstream throttle valve increases, the increased amount is compensated for by the intake air introduced via the upstream throttle valve to maintain the intake pressure at t<atmosphere. This is a great thing because it stabilizes the internal EGR suppression effect in the low load range. 5° (Credit to the invention) Therefore, according to the engine throttle valve control means of the present invention, internal EGR can be suppressed as much as possible in the low load range to maintain good combustibility. , it becomes possible to improve the response performance of the engine, and in high load ranges, internal EGR is actively introduced to reduce engine pumping losses as much as possible, thereby improving the fuel efficiency of the engine. Effects such as being able to achieve the following can be obtained.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an intake system of a four-cylinder automobile engine l equipped with a throttle valve control means according to an embodiment of the present invention. Each combustion chamber 2.2 of this engine 1. ... includes an intake boat 3 that is opened and closed by an intake valve (not shown) and an exhaust boat 4 that is opened and closed by an exhaust valve (not shown), respectively. And each intake boat 3
,3. ... are connected to the surge tank 6 via independent intake passages 5, respectively. Also, this surge tank 6
A main intake passage 7 whose upstream end is open to the atmosphere is connected to the upstream side of the main intake passage 7 .

The main intake passage 7 is provided with an upstream throttle valve 8 supported on a valve shaft l. In addition, each of the independent intake passages 5.5. ... have downstream throttle valves 9, 9 . . . , respectively. ... is provided. The downstream throttle valves 939° are opened and closed in conjunction with each other by a common valve drive shaft 12. The upstream throttle valve 8 and the downstream throttle valve 9 are interconnected by a link mechanism 20, which will be described later, and are opened and closed in conjunction with each other according to predetermined characteristics. In FIG. 1, reference numeral 10 indicates each independent intake passage 5.5. It is an injector installed in...

The link mechanism 20 constitutes the main body of the throttle valve control means of the present invention, and as shown in FIG. 2, the valve drive M! A rotary plate 21 is supported relatively rotatably by the valve drive shaft 12 and has an accelerator wire 30 attached to its arcuate outer periphery. a second lever 25 fixed to the valve shaft 11 of the upstream throttle valve 8, one end of which is connected to the first lever 22 via a pivot pin 26; The engagement pin 27 provided at the end has a link par 24 that is freely engaged with the engagement elongated hole 28 of the second lever 25 (this figure 2 shows the upstream throttle valve). (indicates fully closed state).

The first lever 22 is a spring (not shown).
is always biased in the direction indicated by the arrow (ie, in the opening direction of the downstream throttle valve 9). Further, when the downstream throttle valve 9 is in the fully closed state as described above, the second lever 25 is attached to the rotary plate 21 in the biasing direction thereof.

By engaging with the bar 23, its rotation in the valve opening direction is restricted.

Furthermore, when the downstream throttle valve 9 is fully open, the upstream throttle valve 8 is set to a position open by a predetermined opening degree (opening degree α in FIG. 3), and in this state, the second lever 25 is opened. The relative positions of each member are set so that the engagement pin 27 comes into contact with the end 28a of the engagement elongated hole 28 closer to the downstream throttle valve 9.

The operation of each throttle valve 8.9 in the case of such a link configuration will be explained with reference to FIG.

In this embodiment, as shown in FIG. 3, the engine load area is divided into Area I, Area J, and Area ■ from the low load side, and this Area I is the low load area in the claims. This is true, and area (2) and area (2) correspond to the high load area in the claims. The operating characteristics are set so that the upstream throttle valve 8 becomes fully open at the end of region (2) (full throttle), and the downstream throttle valve 9 becomes fully open at the end of region (2).

To explain this operating characteristic in detail, the condition 1 shown in Fig. 2 is as follows.
When the accelerator wire 30 is pulled from 3 (in other words, the downstream throttle valve 9 is fully open and the upstream throttle valve 8 is opened by the initial opening degree α), the rotating plate 21 first rotates in the direction indicated by the arrow. However, since the restricting action of the stopper 23 of the rotating plate 2I on the second lever 25 is released, the downstream throttle valve 9 begins to open from the fully open position. At the initial stage of opening of the downstream throttle valve 8, the engagement pin 27 of the linker 24 moves freely within the engagement elongated hole 28 of the second lever 25 and maintains a non-engaged state with the second lever 25. Therefore, the upstream throttle valve 8 is maintained at the initial opening degree α. Then, when the operation amount of the accelerator wire 30 reaches point P (see FIG. 3), the opening degrees of the upstream throttle valve 8 and the downstream throttle valve 9 match. Therefore, in a load range lower than this point P, the opening degree of the downstream throttle valve 9 is smaller than that of the upstream throttle valve 8, and the amount of intake air into the combustion chamber 2 of the engine l is mainly determined by this downstream throttle valve 9. In addition, in a higher load range than this point P, the opening degree of the upstream throttle valve 8 becomes smaller than that of the downstream throttle valve 9, and the intake air amount is mainly controlled by this upstream throttle valve 8. become.

Further, when the accelerator wire 30 is pulled and reaches the end of the region I, the engagement pin 27 of the link par 24 comes into contact with the other end 28b of the engagement elongated hole 28, and the operating force of the accelerator wire 30 is applied to the second lever. 25 side. Therefore, when the accelerator wire 30 is pulled further, the upstream throttle valve 8 also moves in the valve opening direction in conjunction with the movement of the downstream throttle valve 9 (state in area H in FIG. 3).

Then, after the downstream throttle valve 9 is fully opened at the end of region (2), only the upstream throttle valve 8 is opened to its fully open position by pulling the accelerator wire 30 (state of region (2)).

Next, the surge tank 6 at the time of valve overlap when each throttle valve 8.9 opens with such characteristics.
The correlation between the intake pressure at the downstream side of the downstream throttle valve 9 and the internal EGR rate will be explained with reference to FIG.

First, the intake pressure of the surge tank 6 is brought to atmospheric pressure by the air introduced into the surge tank 6 through the upstream throttle valve 8 between the end of the previous intake stroke and the start of the current intake stroke.

Therefore, until the accelerator operation amount reaches point P, the atmospheric pressure is maintained as shown by curve III in FIG.

On the other hand, the intake pressure on the downstream side of the downstream throttle valve 9 is
Negative pressure is generated due to the pumping action of the piston (not shown), but since the intake air amount itself is low and the load is in a low load range, the pressure drop is small, and the pressure is maintained at approximately atmospheric pressure as shown by curve llt in FIG.

Further, in such a low load range, the gas pressure of the exhaust gas is also maintained at approximately atmospheric pressure. Therefore, from the point where there is almost no pressure difference between the intake side and the exhaust side, curve a is shown in Figure 4.
, the exhaust gas brought into the combustion chamber 2 at the time of valve overlap, that is, the internal EGR, is kept as small as possible. Therefore, in this region, the combustibility is made good, and the response performance especially during acceleration is improved.

Furthermore, in this case, since the upstream throttle valve 8 is set to a predetermined opening degree α, even if the intake air amount gradually increases and changes, air is smoothly introduced into the surge tank 6 side via the upstream throttle valve 8. and the surge tank 6
The intake pressure inside the tank is stably maintained at atmospheric pressure.

On the other hand, when the accelerator operation amount exceeds point P, the opening degrees of the upstream throttle valve 8 and the downstream throttle valve 9 are reversed, and the intake air amount is mainly controlled by the upstream throttle valve 8. Therefore, since the intake air is throttled by the upstream throttle valve 8, the internal pressure of the surge tank 6 and the downstream pressure of the downstream throttle valve 9 gradually decrease as the amount of accelerator operation increases, that is, the load increases. The maximum negative pressure is reached when the throttle valve 9 is fully opened (see curve L, ■). Thereafter, as the opening degree of the upstream throttle valve 8 increases, the pressure gradually approaches atmospheric pressure.

In this way, the intake pressure changes greatly in the direction of negative pressure in regions (■) and (2), especially in region H (medium load region);
On the other hand, the exhaust gas pressure increases. Therefore, in this region, as shown by curve a3, the internal EG into the combustion chamber 2
The amount of R will increase.

In this case, in this region, even if the amount of intake air is large and the internal EGR is relatively large, it not only has almost no effect on combustibility, but conversely, the pumping loss of the engine is reduced by this large amount of internal EGR introduced. This is an advantage. In other words, the ratio of the amount of fresh air (that is, the amount of intake air introduced while being throttled through the downstream throttle valve 9) to the total intake air amount to the combustion chamber 2 decreases by the amount of internal EGR, and the engine pumping level decreases accordingly. This results in a reduction in gross, which in turn contributes to improving the fuel efficiency of the engine.

The effect of reducing the pumping loss by introducing internal EGR is further increased by introducing exhaust gas directly into the combustion chamber 2 from the exhaust boat side as in this embodiment. That is, the combustion chamber 2 is directly used as internal EGR.
The temperature of the exhaust gas introduced into the exhaust gas can be maintained at a higher temperature than, for example, when the exhaust gas is introduced from the exhaust pipe side through a dedicated passage. In this way, when high-temperature exhaust gas is introduced into the combustion chamber 2 as internal EGR, the temperature inside the combustion chamber 2 becomes high and its internal pressure increases. Therefore, in order to draw intake air into the combustion chamber 2 which has reached such a high pressure, it is necessary to set the opening degree of the downstream throttle valve 9 to be large in advance. Bumping loss due to the throttling action of the throttle valve 9 is further reduced.

In the case of a configuration like this embodiment, as shown in FIG.
In this case, the intake pressure approaches atmospheric pressure and internal EGR decreases, making it possible for the engine to operate at high output.
This provides the advantage that the required output characteristics of the engine can be more closely matched.

Furthermore, although the above embodiments were directed to an intake system equipped with a surge tank, the present invention is not limited to this.
For example, it can be applied to an intake system that does not have a surge tank.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of an intake system of an engine equipped with a throttle valve control means according to an embodiment of the present invention, Fig. 2 is an explanatory diagram of the structure of the link mechanism shown in Fig. 1, and Fig. 3 is a diagram of each throttle valve. Figure 4 shows the intake pressure and internal EG for the accelerator operation amount in the intake system shown in Figure 1.
It is a correlation diagram with R rate. 1... 2... 3... 4... 5... 6... 7... 8... 9. ...... 11... 12... 20... 21... 22.25... 23... 24... 30... ・Engine・Combustion chamber・Intake boat, exhaust boat, independent intake passage, surge tank, main intake passage, upstream throttle valve, downstream throttle valve, valve shaft, valve drive shaft, link mechanism, rotating plate lever, stopper, link bar, accelerator wire No. 1 Figure Engine Combustion Chamber Intake Port Exhaust Port Independent Intake Passage Surge Tank Intake Main Passage Upstream Throttle Valve Downstream Throttle Valve Figure 3: Valve shaft: Valve drive shaft: Link machine 1: Rotating plate; Stopper: Link bar: Accelerator wire Figure 4

Claims (1)

[Scope of Claims] 1. In an engine in which an upstream throttle valve located on the upstream side of intake and a downstream throttle valve located on the downstream side are provided in an intake passage communicating with a combustion chamber of the engine, The throttle valve and the downstream throttle valve are connected to the accelerator operation so that in a low load operating range where the valve opening is small, the opening of the downstream throttle valve is lower than the opening of the upstream throttle valve, A throttle valve control means for an engine, characterized in that the opening of the upstream throttle valve is linked to be lower than the opening of the downstream throttle valve in a high load operating range with a large valve opening. 2. Claim 1, characterized in that the upstream throttle valve is configured to be maintained at a predetermined opening in a low load range.
Throttle valve control means for the engine described.