JPS6235028A - Exhaust turbo supercharger - Google Patents

Abstract

PURPOSE:To reduce the turbo-lag in the following acceleration time by controlling a passage area variable means during the acceleration in such a manner that the exhaust gas passage area becomes small after a predetermined time elapses, thereby preventing the surging from occurring and at the same time keeping the turbine speed high. CONSTITUTION:Intake air quantity signal value Vs, which is sent from an air-flow meter 31, is compared with intake air quantity Vc, which is set inaccordance with both engine speed and the throttle valve opening. In the case of Vs>=Vc, the engine output is judged high, and a two position valve 20 is opened to open the second passage 19. In the case of Vs<Vc but not steep deceleration, the two position valve 20 is closed to close the second passage 19. In the case of both Vs<Vc and steep deceleration, it is judged that in the previous speed-change the engine moved into a decelerating state only when it is Vs>Vc, and after the predetermined (delay) time in accordance with the engine speed have elapsed the second passage 19 is closed and moreover a passage area variable means 26 is controlled in such a way that the exhaust gas passage area becomes small.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust turbo supercharging device that performs supercharging by driving a compressor disposed in an intake passage by a turbine disposed in an exhaust passage. The present invention relates to an improvement in preventing a delay in increasing the turbine rotational speed during operation.

(Prior art) Conventionally, in an exhaust turbocharger, since the rotating part has inertia, it is necessary to accelerate this rotating part during a transient period. Therefore, the turbine rotation speed increases during acceleration. There was a problem with this, resulting in so-called turbo lag, resulting in poor acceleration response. In particular, at low speeds and low loads, the exhaust gas energy is low, so the rotational speed of the rotating parts is very low, and when rapidly accelerating from this state, there is a significant delay, and the rise in boost pressure, that is, the rise in output, is delayed, resulting in poor acceleration performance. cannot be obtained sufficiently.

Therefore, conventionally, in order to deal with this problem,
As disclosed in Japanese Patent No. 1230, the exhaust gas passage area variable means is provided to vary the exhaust gas passage area upstream of the turbine, and the exhaust gas passage area variable means is controlled according to the engine operating state to control low speed and low speed. By reducing the exhaust gas passage area and increasing the exhaust flow velocity under load, the turbine rotation speed at low speeds and low loads is maintained at a high level in preparation for the next acceleration, and during subsequent accelerations the compressor is quickly turned to high rotation speed. A system has been proposed that reduces turbo lag and improves acceleration.

(Problem to be Solved by the Invention) However, when maintaining the turbine speed at a high level in preparation for the next acceleration as described above, during deceleration when the throttle valve is fully opened, the exhaust gas is If the passage area is immediately reduced, the pressure in the intake passage upstream of the throttle valve will remain high as the turbine rotational speed remains high, and the intake air volume will rapidly decrease, causing the turbo characteristics to cross the surging line. I exceeded it (
(see Fig. 5), phenomena such as generation of abnormal noise and reverse rotation of the turbine occur, which adversely affects the durability of the supercharger and poses a problem in terms of reliability. In particular, experiments have shown that this surging noise becomes louder when decelerating from a high engine speed range.

The present invention has been made in view of this point, and its purpose is to delay the exhaust gas passage area during deceleration without immediately reducing it, so that the turbine rotation speed is maintained to a certain extent so that the turbo characteristics do not exceed the surging line. follows the decrease in intake air volume to ensure the reliability of the exhaust turbo supercharger, while maintaining the turbine rotation speed as high as possible during acceleration to shorten the turbo lag during the next acceleration and improve acceleration response. It is about improving sexuality.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention provides exhaust turbo supercharging 4! a passage area variable means for varying the area of the exhaust gas passage upstream of the turbine; a deceleration detecting means for detecting when the engine is decelerating; and a control means for controlling the two-passage area variable means so as to reduce the area.

(Function) With the above configuration, in the present invention, the exhaust gas passage area upstream of the turbine of the exhaust turbocharger is kept large during a predetermined period at the beginning of deceleration, and is then reduced to a small value, so that Sometimes, the turbine speed is kept as high as possible within a range where the turbo characteristics do not exceed the surging line. As a result, the compressor rotates quickly at a high speed during the next acceleration without impairing the reliability of the exhaust turbo supercharger, reducing turbo lag and providing good acceleration performance.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows the overall schematic configuration of an engine equipped with an exhaust turbocharging device of the present invention. In the figure, 1 is an engine body, 2 is a combustion chamber formed above a piston 3 of the engine body 1, and the combustion chamber 2 has an intake port 6 that is opened and closed by an intake valve 4 and an exhaust valve 5, respectively. and the exhaust boat 7 is open. The intake port 6 has an intake passage 8 for supplying intake air to the combustion chamber 2, and an exhaust boat 7.
are connected to exhaust passages 9 for discharging exhaust gas from the combustion chamber 2, respectively. The upstream end of the intake passage 8 is open to the atmosphere via an air cleaner 10, and in the middle of the intake passage 8, a throttle valve 11 for controlling the amount of intake air and a surge valve as an intake expansion chamber are located in the middle of the intake passage 8. Tanks 12 are respectively provided.

16 is an exhaust turbo supercharger, and the exhaust turbo supercharger 16 includes a turbine 16a interposed in the exhaust passage 9, and a shaft disposed upstream of the throttle valve 11 in the intake passage 8 and connected to the turbine 16a. The compressor 16b is drivingly connected to the compressor 16b via the exhaust gas flow, and the compressor 16b is driven by the turbine 16a rotated by the exhaust gas flow to supercharge the intake air.

The exhaust passage 9 upstream of the turbine 16a of the exhaust turbocharger 16 is divided into a first passage 18 and a second passage 19 by a partition wall 17. The upstream end of a bypass passage 14 for regulating maximum boost pressure, which allows the fuel to flow down bypassing the turbine 16a, is open. Also.

A two-position valve 2o that opens and closes the second passage 19 is disposed at the upstream end of the second passage 19. A diaphragm device 21 as an actuator is connected to the two-position valve 20, and a three-way solenoid valve 23 is connected to the diaphragm device 21 through a pressure passage 22. , by opening the pressure passage 22 to the atmosphere via the atmospheric pressure passage 24 or by applying negative intake pressure downstream of the throttle valve 11 in the intake passage 8 through the negative pressure passage 25, the diaphragm device 21 The third position valve 20 is selectively switched between the closed position and the open position shown in the figure. Therefore, the second passage 1 by the three-position six-position valve 20
9 constitutes a passage area variable means 26 that changes the exhaust gas passage area upstream of the turbine 16a of the exhaust turbocharging 1fi16 in two stages. The operation of the three-way solenoid valve 23 is controlled by a control unit 30 comprising a CPU or the like. The control unit 30 receives a signal from an air meter 31 that detects the amount of intake air immediately downstream of the air cleaner 10, a signal from a throttle opening sensor 32 that detects the throttle valve opening, and a signal from the engine. A signal from an engine rotational speed sensor 33 that detects the rotational speed can be input. still,
In the figure, 34 is a waste gate valve that opens the bypass passage 2o.

Next, the third place purchase 2 by the control unit 30
0 position switching control will be explained based on the flowchart of FIG. After starting, in step S+, first, the intake air amount signal 1+ (IVs) from the air flow meter 31, the throttle angle signal value TV from the throttle opening surface sensor 32,
O and the engine rotational speed signal value E rpm from the engine rotational speed sensor 33 are read respectively.

After that, in step S2, the intake air amount signal value VS is set to the third value.
As shown in the figure, the magnitude is compared with the corresponding intake air IVc on the position switching line 9 of the third position valve 20 set according to the engine speed and the throttle valve opening, and in the case of No of Vs≧VC, It is determined that high output is required, and in step S3, the third position valve 20 is controlled to the open position to open the second passage 19, and the process returns.

On the other hand, in the above Stella 7Sz, Vs < Vc (7) YE
In the case of S, it is determined that it is deceleration and further step $4 is performed.
It is determined whether or not the engine is in the rapid deceleration range from the high engine speed shown in FIG.
At 9, the second passage 19 is closed by controlling the third valve 20 to close, thereby maintaining the turbine rotational speed at a high level, and returning. Then, in step S4 above, YE is in the rapid deceleration region.
In the case of S, it is determined that the frequency of surging is high, and first, in step S5, it is determined whether or not the previous high output request was Vs > Vc, and deceleration is performed only if VS > VC is YES. Immediately after the transition to the state, in step S6, since the higher the engine speed, the louder the surging sound, a delay time T proportional to the increase in the engine speed is set, as shown in FIG. After that, in step S7, "1°° is subtracted from the delay time T, and in step S8
It is determined whether the delay time T has reached the ll OII value or not, and in the case of No (T≠○), it is determined that the turbo characteristics exceed the surging line, and the process returns to step S3 to control the closing of the third position valve 20. Continues to maintain the open state of the second passage 19 and return, while in the case of YES at T=O, it is determined that the surging line will not be crossed, and the third position valve 20 is placed in the closed position for the first time in step S9. The control closes the second passage 19 and returns.

Therefore, in the operation flow shown in FIG. 2 above, step S
2, S4 constitutes a deceleration detecting means 36 that detects when the engine 1 is decelerating. Further, in steps 85 to S9, the passage area variable means 26 is controlled to close the second passage 19 and reduce the exhaust gas passage area after a predetermined time (delay time T) at the beginning of deceleration according to the engine speed has elapsed. It constitutes a control means 37.

Therefore, in the above embodiment, in the graph of the intake air amount ■C of the engine and the pressure P of the intake passage 8 upstream of the throttle valve 11 shown in FIG. When the second passage 19 is open, the amount of intake air Q is as shown by the solid line (thick line) in the figure.
The turbine 16a and compressor 16b of the exhaust turbo supercharger 16 are
The rotational speed increases, and the pressure P upstream of the throttle valve increases.

When the throttle valve 11 is suddenly closed from this state and the throttle valve 11 is suddenly decelerated, the second passage 19 is kept open for a delay time T (see Fig. 4) corresponding to the engine speed, and then the third passage valve 20 is opened. is controlled to the closed position and the second passage 19 is closed, so that the pressure P upstream of the throttle valve 11 does not exceed the surging line S (shown by the thin line in the figure) as shown by the solid line (very thick line) in the figure. Along the surging line, the intake air ff1Qa decreases as the intake air ff1Qa decreases.As a result, for example, when the second passage 19 is immediately closed during deceleration, the turbo characteristic crosses the surging line as shown by the broken line in the figure. This prevents phenomena such as abnormal noise and reverse rotation of the turbine 16a, and also prevents the second
The rotational speed of the turbine 16a is kept as high as possible, and the turbo efficiency is improved, compared to the case where the passage 19 is still kept open and the pressure upstream of the throttle valve immediately decreases as shown by the chain line in the figure. Therefore, during the next acceleration, the rotation of the compressor 16b increases quickly and has excellent responsiveness, and the supercharging pressure increases early to improve output, reducing turbo lag and achieving good acceleration response. It will be done. Therefore, it is possible to prevent surging during deceleration and maintain high reliability of the exhaust turbo supercharger 16, while improving acceleration response during the next acceleration.

FIG. 6 shows another embodiment of the present invention, in which, instead of setting the delay time 1- (see FIG. 4) according to the engine speed in the above embodiment, the pressure upstream of the throttle valve 11 is set. The second passage 19 is kept open for a predetermined period of time until the surging generation pressure reaches the set value of non-vortex.

That is, in the overall schematic configuration of the engine with an exhaust turbo supercharging device shown in FIG. 6, in addition to the configuration shown in FIG. , the pressure signal is input to the control unit 30.

In addition, in the operation flow of the controller 30 in FIG. 7, in step S+', the intake air signal value Vs is
- Lecture opening signal value TVO, engine rotational speed signal value E rp
In addition to m, the pressure signal value P6 from the pressure sensor 40 upstream of the throttle valve 11 is read.

Then, in step 82', VS≧V as in the above embodiment.
When a high output is required for NO of C, the third position valve 20 is controlled to the closed position in step 83', the second passage 19 is opened, and the process returns.

On the other hand, when the deceleration is YES (VS < VC) in step $2', the pressure signal 1 mPa upstream of the throttle valve 11 is set to the pressure upstream of the throttle valve corresponding to the intake air ff1Qa on the surging line S in FIG. 5 in step S4'. The magnitude is compared with the set value pc which is less than the value (surging generation pressure value), and if it is in the surging generation region where Pa>PC (No), the process returns to step S3' and the second passage 19 is maintained in the open state, while pB If the surging generation region of YES of <pc is exited, the throttle valve opening T is changed in step Ss'.
VO is not set value Tc FI14 (TVO<Tc) After confirming the deceleration state of YES, step 86'
Then, the third position valve 20 is controlled to close, one second passage is closed, and the process returns. Then, in the fifth step 85', TVO≧
When the NO acceleration request reaches Tc, the process proceeds to step S3' and controls the third position valve 20 to the closed position to open the second passage 19 and prepare for generation of high output. Therefore, step 84 above
'~Ss' controls the passage area variable means 26 to close the second passage 19 and reduce the exhaust gas passage area after a predetermined time has elapsed until the pressure Pa upstream of the throttle valve 11 becomes less than the set value 10. ] constitutes IIJ til1 means 37'.

Therefore, in this example as well, as in the above example,
The turbine speed is increased as much as possible within a range where the turbo characteristics do not exceed the surging line, ensuring reliability of the exhaust turbo supercharger 16, and reducing turbo lag during the next acceleration to improve acceleration response. can be achieved. Further, as another embodiment, the valve may be simply closed when the number of rotations has decreased to a predetermined number.

In the above embodiment, the passage area variable means 26 was constructed by opening and closing the second passage 19 by the third position direct push 20.
Alternatively, it may be configured to be continuously variably controlled by a movable plate or the like disposed in the volute chamber of the turbine 16a of the exhaust turbocharger 16.

(Effects of the Invention) As explained above, according to the exhaust turbocharging device of the present invention, during deceleration, the exhaust passage upstream of the turbine is narrowed after a predetermined period of time has elapsed, thereby preventing the occurrence of surging and providing reliable It is possible to maintain the turbine rotation speed as high as possible while ensuring performance, reduce turbo lag during acceleration, and improve acceleration response.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, in which Fig. 1 is a general schematic diagram of an engine equipped with an exhaust turbo supercharging device, Fig. 2 is a flowchart showing the operation of the control unit, and Fig. 3
The figure shows the output demand range, deceleration range, and sudden deceleration range of the engine operating state. Figure 4 shows the continuous time characteristics of exhaust passage throttling control with respect to engine speed. Figure 5 shows the intake air amount. FIG. 4 is a diagram showing an example of turbo characteristics during acceleration, steady running, and deceleration in relation to the pressure upstream of the throttle valve. 6 and 7 show other embodiments, FIG. 6 being a diagram corresponding to FIG. 1, and FIG. 7 being a diagram corresponding to FIG. 2. DESCRIPTION OF SYMBOLS 1...Engine body, 8...Intake passage, 9...Exhaust passage, 11...Throttle valve, 16...Exhaust turbo supercharger, 16a...Turbine, 16b...Combrella 2 -118...first passage, 19...second passage,
20... Third position direct push, 26... Passage area variable means, 3
o...Control unit, 36...Deceleration detection means, 37.37'...Control means. Patent applicant Mazda Motor Corporation Representative
Person Patent Attorney Mae 1) Hiroshi, +:゛・-゛II

Claims (1)

[Claims] (1) In an exhaust turbo supercharging device that performs supercharging by driving a compressor disposed in an intake passage by a turbine disposed in an exhaust passage, the passage area is variable by varying the area of the exhaust gas passage upstream of the turbine. a deceleration detecting means for detecting when the engine is decelerating; and a control means for receiving the output of the deceleration detecting means and controlling the passage area variable means to reduce the exhaust gas passage area after a predetermined period at the beginning of deceleration. An exhaust turbo supercharging device characterized by being equipped with.