JPS62170721A - Supercharged engine - Google Patents

Abstract

PURPOSE:To improve the transient torque characteristics of an engine in which, at the time of low-speed operation, the intake inertial effect is utilized to perform a natural air intake supercharging by providing a supercharger on the downstream side from a volume part for reflecting pressure along an intake passage and then providing a bypass provided with a closing valve taking a long way around said supercharger. CONSTITUTION:In the middle of an intake passage 3, extending from the intake downstream side to the upstream side air cleaner 4, are placed, in consecutive order, a rotary valve 6, a throttle valve 7, a supercharger 8, which are for obtaining an intake slow opening action at the time of natural air intake, and a volume part 9 for reflecting pressure at the time of natural air intake. In addition, the No.1 by-ass passage 10 is provided in such a manner as to detour the rotary valve 6, and in the middle of the passage 10 is placed the No.2 shutter valve 14. And further, in the operating range, where the natural air intake is performed, other than the operating range including the high-speed high-load operation, a control is performed so that the No.1 shutter valve 11 is closed and the No.2 shutter valve 14 is opened.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a supercharged engine.

(Prior art) In the past, in order to increase the output of an engine, it was supposed to be supercharged using a supercharger such as a turbocharger. This has been widely put into practical use.

In engines equipped with a supercharger such as the above-mentioned turbocharger, a configuration is generally adopted in which a surge tank for buffering negative pressure waves is installed in the intake passage downstream of the supercharger, and supercharging is performed by the supercharger. For example, Utsukai Showa 59-91422
(see publication).

However, in the above-mentioned supercharged engine, a time lag occurs due to the inertia of the turbine, especially when accelerating from a low speed state, and sufficient supercharging cannot be achieved to meet the acceleration request. Generally, the compression ratio is low to prevent knocking, so the output performance is inferior to that of a naturally aspirated engine, and there is a particular problem in that it lacks acceleration response.

Therefore, at the initial stage of acceleration, the supercharger is bypassed to perform natural intake, which takes advantage of the intake inertia effect to achieve efficient natural intake, but when a certain period of time has passed after acceleration. It is proposed that the output be improved by supercharging the engine using a supercharger.

However, when the intake inertia effect due to natural intake is combined as described above, the following new problem arises.

In other words, in order to increase the intake inertia effect (higher volumetric efficiency) due to natural intake at low engine speeds, it is necessary to increase the distance from the intake valve to the volume part that is the pressure reflection part. If this is combined with the effect of increasing negative pressure by slow intake closing ζJ using a rotary valve or the like, it becomes necessary to expand the volume section itself to a larger volume. Moreover, if the large negative pressure acts on the compressor of the supercharger, it will cause surging, so in order to avoid this, the supercharger must be placed further away from the intake valve than the intake valve. It must be installed on the flow side.

As a result, the length from the supercharger to the engine's intake valve becomes significantly longer, making it extremely difficult to mount the product on a vehicle, and at the same time, the volume part of the supercharger is located downstream of the compressor. As a result, the downstream volume is significantly expanded, which causes a problem in that the supercharging effect during supercharging is greatly reduced, and in particular, the torque characteristics during transient times are also significantly deteriorated. As a result, the response at high speeds and high loads becomes worse.

(Means for Solving the Problems) The present invention has been made with the aim of solving the above problems. , In a supercharger engine that performs naturally aspirated supercharging by utilizing the intake inertia effect due to the intake negative pressure generated during the intake stroke of the engine at low speeds, from the volume part of the intake passage. A bypass passage located downstream of the intake air and bypassing the supercharger and the supercharger described in - is provided respectively, and the bypass passage is closed at least in a predetermined operating range including at high speeds and high loads. This consists of installing an on-off valve that is opened in other operating areas.

(Function) According to the above method, a bypass passage for naturally aspirated air is provided in parallel to the turbocharger, and an on-off valve that closes at high speeds and high loads is installed in the same passage, so that the turbocharger does not operate at low speeds. In some cases, it is possible to perform efficient naturally aspirated supercharging using the intake inertia effect through the bypass passage, and it is possible to sufficiently improve the initial response during acceleration. It is possible to prevent intake negative pressure from directly acting on the supercharger. Therefore, it becomes possible to install the turbocharger on the downstream side of the above-mentioned volume section, greatly reducing the intake passage volume downstream of the compressor of the turbocharger, thereby reducing the overcharging response etc. The feeding characteristics can be improved. Moreover, the above bypass passage has high-speed
Since it is equipped with an on-off valve that closes when the load is high, it is possible to obtain sufficient supercharging action from the supercharger at high speeds and high loads when the supercharger is acting, and it also provides sufficient transient response under these conditions. It becomes possible to improve the performance.

(Example) FIGS. 1 to 5 show a supercharged engine according to an example of the present invention.

First, in FIG. 1, reference numeral I designates an engine body, and an intake manifold 2 is integrally connected to an intake port la provided with an intake valve 5 of the engine body 1. As shown in FIG. Further, one end of an intake passage 3 formed by an intake pipe is communicated with the intake manifold 2, and the other end of the intake passage 3 is extended in communication with the air cleaner 4. In the middle of the intake passage 3, from the intake downstream side to the upstream side air cleaner 4, there is a supercharger consisting of a rotary valve 6, a throttle valve 7, and a turbocharger for obtaining a slow intake closing action during natural intake. A compressor section) 8 and a volume section 9 for pressure reflection during natural intake are sequentially installed at predetermined intervals. A first bypass passage 10 that bypasses the rotary valve 6 is provided in the rotary valve 6 portion of the intake passage 3, and the first bypass passage 10 is opened and closed as desired by a predetermined engine control unit 20. A first shatter valve 11 is provided. In addition, a second bypass passage 12 is formed in a portion of the intake passage 3a upstream of the two-legged throttle valve 7 in which the supercharger 8 is provided, and a second bypass passage 12 is formed that bypasses the supercharger 8. A second shutter valve 14 is provided in the engine control unit 20.
The opening/closing is controlled under predetermined conditions, which will be described later.

On the other hand, the engine control unit 20 is configured mainly with a microprocessor, for example,
The control operations shown in FIGS. 2 to 4 are performed depending on the operating state of the engine to control the first and second yutter valves II and +4 as shown in FIG. 4.

That is, the flowchart in FIG. 2 shows a control operation for solving the conventional problems explained in the prior art section and improving responsiveness during acceleration using the configuration shown in FIG. 1 above. It is.

First, in step St, the throttle opening θ and the intake negative pressure P at that time are read into the memory of the engine control unit 20 as detection parameters for detecting the acceleration state in the operating state.

Next, in step S, the two parameters θ are determined.

P is compared with the previous data of a predetermined period t, and the above-mentioned θ, the amount of change dθ/dt of P and dP /dt within the time period are calculated. Then, the process further proceeds to step S3, and
The values of θ/di and dP/dt are set values C8 and C for determining the acceleration state as the first condition, respectively.
It is determined whether both are greater than 7. As a result, if YES, the second
The process advances to step S4 to determine the condition, while if the other answer is No, the process returns to steps 81 to S3.

'' When the process proceeds to step S4, it is further determined whether the absolute value of the intake negative pressure P is larger than a predetermined set value c3 as a second condition for determining the acceleration state. As a result, YES (
acceleration), the process proceeds to steps 85 to S7 to set a control time td for executing natural intake.

On the other hand, in the case of No, the above step S is performed again.

~Return to S4.

1. Setting of the control time td for executing natural intake is performed as follows.

That is, first, in step S5, the engine speed N is read into the memory of the engine control unit 20, then in step S8, the gear shift position of the transmission at the read engine speed N is detected, and finally, in step S7, the gear shift position of the transmission is detected. A natural intake execution time corresponding to the selected shift position is prepared in advance (a plurality of data is mapped as map data in the memory of the engine control unit 20 corresponding to each gear).
For example, the engine rotation speed N is read out from a corresponding map shown in FIG. 4 and set as a reference. In this case, the reason why the set time characteristics change depending on the gear shift position as described above even at the same engine speed is that the torque characteristics necessarily differ depending on the shift gear.

When natural intake is performed by the above control operation, the valve control section of the engine control unit 20 first operates at t4 at the initial stage of acceleration, as shown in FIG.
At the same time, the first shutter valve 11 is closed, and at the same time, the second shutter valve 14 is opened.

On the other hand, in this state, the rotary valve 6 is closed,
The intake valve 5 is opened a predetermined time later than when the intake stroke on the engine side is started and the intake valve 5 is opened. Therefore, when the low-return valve 6 is opened, the late closing of the intake air achieves natural intake supercharging with high intake efficiency due to the intake inertia effect due to the large intake negative pressure. As a result, it becomes possible to sufficiently improve the responsiveness at the initial stage of acceleration.

Then, when the set natural intake execution time td has elapsed, the first shutter valve I+ is opened, while the second shutter valve 14 is closed and the supercharger 8
The side bypass passage is brought into communication with the intake boat Ia of the engine 1, and the supercharger 8 comes into operation. In this case, as shown in -1-, the supercharger 8 is located on the intake downstream side of the volume portion 9, and the bypass passage 12 for natural intake is installed in a bypass state. As a result, the intake passage volume on the downstream side of the compressor of the supercharger 8 can be greatly reduced without fear of damage due to surging during natural intake, and as a result, transients at high speeds and high loads when the supercharger 8 acts are reduced. It becomes possible to further improve responsiveness.

Now, if we show this result in a graph, it will look like Figure 5.The supercharging effect of natural intake and turbocharger, as well as the slow intake closing effect of the low-return valve, can be combined, especially from low speed range to high speed range. It is clear that the transient torque characteristics of both are improved.

(Effects of the Invention) As explained in 2 below, the present invention provides a supercharger and a volume part for pressure reflection in the middle of the intake passage of an engine, and at low speeds, the intake negative pressure generated in the intake stroke of the engine is reduced. In a supercharged engine that performs naturally aspirated supercharging by utilizing the intake inertia effect of A bypass passage is provided to detour the vehicle, and the bypass passage is further provided with an on-off valve that is closed at least in a predetermined operating range including high speeds and high loads, and is opened in other operating ranges. It is characterized by:

Therefore, according to the present invention, a naturally aspirated bypass passage is provided in parallel to the turbocharger, and an on-off valve that closes at high speeds and high loads is provided in the same passage, so that the bypass passage is closed at low speeds when the turbocharger does not operate. Through this, efficient naturally aspirated supercharging can be achieved using the intake inertia effect, and the initial response during acceleration can be sufficiently improved, and the intake negative pressure during the naturally aspirated state can be Direct action on the supercharger can be avoided. Therefore, it becomes possible to install the turbocharger on the downstream side of the above-mentioned volume section, greatly reducing the intake passage volume downstream of the compressor of the turbocharger, thereby reducing the supercharging response and other problems. The feeding characteristics can be improved.

Moreover, since the above-mentioned bypass passage is equipped with an on-off valve that closes at high speeds and high loads, it
When the load is high, sufficient supercharging action by the supercharger can be obtained, and transient response under such conditions can also be sufficiently improved.

[Brief explanation of drawings]

Fig. 1 is an intake system diagram of a supercharged engine according to an embodiment of the present invention, Fig. 2 is a flowchart showing the control operation of the engine, and Fig. 3 is a flowchart used in the control operation of the same flowchart. FIG. 4 is a time chart showing the valve control operation in the engine control unit of the engine, and FIG. 5 is a transient torque characteristic chart of the engine showing the effects of the present invention. 1...Engine body 1a...Intake boat 2...Intake manifold 3...Intake passage 4...Air cleaner 6...Lower valve 7... - Throttle valve 8...Supercharger 9...Volume section 10...First bypass passage 11...First shutter valve 12...Second bypass passage 14...Second shutter valve 20...Engine control unit Figure 3

Claims (1)

[Claims] 1. A supercharger and a pressure-reflecting volume part are installed in the middle of the engine's intake passage, and at low speeds, natural intake supercharging is performed by utilizing the intake inertia effect due to the intake negative pressure generated during the intake stroke of the engine. In the supercharged engine, the intake passage includes the supercharger and a bypass passage that bypasses the supercharger and is located on the intake downstream side of the volume portion of the intake passage. - A supercharged engine characterized by being provided with an on-off valve that is closed in a predetermined operating range, including during high loads, and opened in other operating ranges.