JPS59134326A - Device for controlling super-charged pressure of engine provided with turbo-supercharger - Google Patents

Abstract

PURPOSE:To control maximum super-charged pressure by a single signal source, by providing such an arrangement that, when the pressure of exhaust gas reaches a set vaue, the exhaust gas pressure is lowered to the set value in accordance with the exhaust gas pressure. CONSTITUTION:By means of selector valves, an engine 1 is operated with the assistance of a low speed turbo-supercharger 8 upon low speed operation, but is operated with the assistance of a high speed turbo-supercharger 9 upon high speed operation. When super-charged pressure produced in a downstream side intake-air passage 2d becomes maximum, the exhaust gas pressure of an upstream side exhaust gas passsage 3u also increasses accordingly, and therefore, a super-charging control valve 22 is operated to be opened since the exhaust gas pressure introduced into a positive pressure chamber 24c in a control diaphragm device 24 overcomes the set load of a coil spring 24f.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a plurality of turbo superchargers each comprising a turbine driven by engine exhaust gas and a blower connected to the turbine by a rotating shaft, and each of the turbines and the blower is connected to the turbine. This invention relates to an engine with a turbo supercharger arranged in parallel in an exhaust passage and an intake passage of the engine.

Conventionally, engine output performance has been improved by using a turbocharger to boost intake air pressure and improve charging efficiency.
The technical idea of achieving the second goal is well known, and there is currently a demand for improving output performance by supercharging not only when the engine is operating at high speeds but also when operating at low speeds.

By the way, it is actually extremely difficult to satisfy the above two requirements with a single turbocharger from the standpoint of turbocharger efficiency, and it is difficult to satisfy the requirements listed in the following paragraphs with a single turbocharger. A technical idea has been proposed to meet these requirements by doing so (see Japanese Utility Model Application Publication No. 56-15≦]626, and Japanese Patent Application Publication No. 56-15+'l-]18117).

Additionally, a turbocharger has the characteristic that the supercharging pressure increases almost in proportion to the increase in engine speed, but increasing the supercharging pressure unnecessarily is not desirable from the standpoint of engine reliability. , normally the boost pressure is less than a certain value - (ζ
It is necessary to control the maximum boost pressure so that it does not increase. The maximum boost pressure is controlled in the low speed range, as described above.
When supercharging is performed in both high speed ranges, it is necessary to prevent knocking not only in the high speed range but also in the low speed range.

Therefore, in an engine in which multiple turbochargers are installed in parallel as described above, the turbine and blower of each turbocharger must be arranged and connected in parallel to the exhaust passage and intake passage of the engine, respectively. In addition, the structure of the intake and exhaust passages is complicated, and there are differences in passage resistance between each intake passage and each exhaust passage where each turbocharger is arranged. In engines that use turbo superchargers by switching, there is a problem that the operating range of each turbo supercharger is different.
There is a problem in that controlling the boost pressure, especially the maximum boost pressure, becomes complicated and difficult. In other words, when a pressure sensor is simply installed downstream of a blower to detect the boost pressure, as in the case of an engine equipped with a single turbocharger (commercially available models have a pressure sensor integrated directly downstream of the blower), ) alone, the operating range of each turbocharger may be different, or even if the operating range is not different, the individual turbochargers (because of differences in performance, differences in passage resistance, etc.) , it becomes difficult to obtain an accurate control signal for the maximum boost pressure of the supercharge air actually supplied to the engine, and in order to obtain an effective control signal, it is necessary to correlate the boost pressures of each turbocharger. There may be problems with the control system, such as the need to take additional steps, which may complicate the control process.

The present invention has been made in view of such problems, and includes:
Exhaust pressure in the exhaust passage between the engine and the branch point where the exhaust passages upstream of each turbine of multiple turbochargers arranged in parallel diverge, and when this exhaust pressure reaches a set value, the exhaust A maximum boost pressure control device is provided that limits the boost pressure to the maximum boost pressure by reducing the exhaust pressure to an exhaust pressure equal to the set value in response to the pressure, and the maximum boost pressure is controlled by a single signal source. It is an object of the present invention to provide a supercharging pressure control device for a turbocharged engine that can effectively and reliably control.

Hereinafter, the present invention will be described in more detail with reference to ν1 based on the illustrated embodiments.

<First Embodiment> In FIG. 1, 1 is an engine, 2 is an intake passage of the engine 1, 3 is an exhaust passage of the engine 1, and 4 is the highest point of the intake passage 2 for measuring the momentary intake air amount of the engine 1. The air 70-sensor 5.6 interposed in the upstream portion is the first and second branch intake passages formed in parallel between the air 70-sensor 4 downstream of the intake passage 2 and the upstream of the throttle valve 7; 9 is the first. Blower 8 interposed between the second branch intake passages 5 and 6
a19a is formed by bifurcating the exhaust passage 3 into two parts. These are low-speed and high-speed turbo superchargers connected by rotary shafts 8c and 9c to turbines 8b and 9b, respectively, interposed in the second branch exhaust passage 10.11.

2. The low continuous use turbo supercharger 8 is a turbo supercharger that has good efficiency in the low speed range of the engine 1, and during low speed operation of the engine, the first branch exhaust passage 1 ( ) and the second branch With the exhaust switching valve 12 provided at the branch part 3a with the exhaust passage 11 closing the second branch exhaust passage 11, the exhaust gas flowing down the first branch exhaust passage 10 switches the turbine E.
')I] is driven, the blower 8a, which is linked to the rotation of the turbine 81], boosts the pressure of the intake air, thereby supercharging the ennon 1 at low speed.

, 1: Turbo supercharging for high speed (Iku 9 is a turbo supercharger having good efficiency in the high speed range of Ennon 1, and when the engine 1 is operated at high speed, the exhaust switching valve 1
2 and 1st. As shown by the dotted line in the figure, the intake switching valve 13 provided at the confluence section 2a of the second branch intake passage 5.6
When the branch exhaust passage 10 and the first branch intake passage 5 are closed, while the second branch exhaust passage 11 and the second branch intake passage 6 are opened, the turbine 9b is driven by the exhaust gas flowing down the second branch exhaust passage 11. Blower 9 linked to this
At step a, the pressure of intake air is increased and the engine 1 is supercharged via the second branch intake passage 6. In other words, when the engine 1 is operating at high speed, the high-speed turbocharging (Iku 9 performs supercharging instead of the low-speed turbocharging 8!8).

Reference numeral 14 uses the output signal of the air flow sensor 4 as a basic manual signal to determine the opening time of the fuel injection valve 15 installed downstream of the throttle valve 7 in the intake passage 2 and the exhaust and intake switching valves 12 and 13. As shown in FIG. 2, this is a control circuit that controls switching of the electromagnetically actuated actuators 16 and 17 provided respectively.As shown in FIG. While the fuel injection valve 15 is opened, the comparison circuit 1
9, the intake air amount and the set value are compared, and when the intake air amount does not reach the set value and the engine 1 is running at low speed, each of the actuators 16 and 17 is held inactive, and when it reaches the set value or more, each actuator 16+17 is is actuated via the amplifier circuit 20 to switch each switching valve 12, 13 from the solid line position to the dotted line position in FIG.

Again, in FIG. 1, 21 is the first . From the upstream exhaust passage 3u between the branch part 3a of the second branch exhaust passages 1o and ii and the engine 1, the downstream exhaust passage bypasses the turbines 8b and 9b of the low-speed and high-speed turbo superchargers 8 and 9. 3d side, an exhaust bypass passage 22, a supercharging pressure control valve that opens and closes a valve seat 23 provided in the middle of the exhaust bypass passage 21;
24 is a Guya 7 ram device for controlling the supercharging pressure control valve 22 supported by the Guyaflame 24b via a rod 24a, and 25 is a positive pressure chamber 24c of the Guyaflam device 24 for control, and an upstream exhaust This is an exhaust pressure introducing passage that introduces the exhaust pressure of the passage 3u. Another chamber 24d, which is separated from the positive pressure chamber 24c by the Gouya 7 ram 24b of the control Gouya 7 ram device 24, is formed as an atmospheric chamber communicated with the atmosphere through the atmosphere opening hole 24e, and this atmospheric chamber 24d
A coil spring 24f is compressed inside, and the set load of this coil spring 24f is set according to the exhaust pressure corresponding to the maximum boost pressure that is the control target.

As mentioned above, this maximum boost pressure is basically set in consideration of the reliability of Ennon 1.

With the above configuration, the supercharging pressure generated in the downstream intake passage 2d by the low-speed turbo supercharger 8 during low-speed operation of the engine 1 and by the high-speed turbo supercharger 9 during high-speed operation is as described above. When the maximum boost pressure is reached, the exhaust pressure in the upstream exhaust passage 3u increases accordingly, and the Z1 pressure introduced into the positive pressure chamber 24c of the control diaphragm device 24 exceeds the set load of the coil spring 24f. As a result, the Guya 7 ram 241J is displaced and the supercharging pressure control valve 22 is opened, thereby communicating the exhaust bypass passage 21 in series. Therefore, part of the exhaust gas bypasses each turbine 8b, 9b by the exhaust bypass passage 21 and flows into the downstream exhaust passage 3d, reducing the driving force of the turbines 8b, 9b, resulting in supercharging of the downstream intake passage 2d. Reduce the pressure to below the maximum boost pressure. Therefore, the supercharging air supplied to the engine 1 is maintained below the maximum supercharging pressure, and the engine 1 is operated satisfactorily without deteriorating its reliability, and exhibits good output performance due to supercharging.

That is, in the first embodiment, the first. second branch exhaust passage io,
By using the exhaust pressure of the upstream exhaust passage 3u between the branch part 3a of ii and the engine 1, the low-speed and high-speed turbo superchargers 8 and 9 are switched and used according to the operating state of the engine 1. Even in this case, the maximum supercharging pressure of the supercharging air actually supplied to the engine 1 can be accurately controlled without any complication of control.

In the above embodiment, the maximum boost pressure was controlled using the exhaust bypass passage 21, but as shown by the imaginary line in FIG. 1, the maximum boost pressure was controlled using the intake bypass passage 26. Let's do it ()I.

That is, a supercharging pressure control valve 27 that opens and closes the intake bypass passage 26 that communicates the intake passage 2d downstream of the intake switching valve 13 with the intake passages 2 and 1 upstream of each blower 8a and 9a is provided. It is supported by the same control Gouya 7 ram device 28 as described above, and the exhaust pressure of the upstream exhaust passage shaft is introduced into the positive pressure chamber of the control Gouya 7 ram device 28 through the exhaust pressure introduction passage 29, thereby achieving supercharging. The supercharging pressure may be controlled by bypassing the blower 8a or 9a and guiding a portion of the supercharging air to the upstream intake passage 2u when the pressure reaches a preset maximum supercharging pressure. <Second Embodiment> The second embodiment shown in FIG.
The secondary turbo superchargers 30 and 31 are installed in parallel, and when the engine 1 is running at low speed with a small intake air amount, when the primary turbo supercharging engine 1 is running at high speed, the primary and secondary turbo supercharging (multiple
The present invention is applied to a type of turbocharged engine that performs supercharging by sharing the intake air amount increased by 0.31.

For this reason, a check valve 32 is provided downstream of the blower in the second branch intake passage 6 in which secondary turbocharging is provided, while a turbine 31 for secondary turbocharging is provided.
An exhaust control valve 33 is provided upstream of the turbine in the second branch exhaust passage 11 in which the second branch exhaust passage 11 is interposed.
0-The intake air amount detection signal of the sensor 4 is compared with the set value, and when the intake air amount exceeds the set value, the comparison circuit 19 connects the actuator provided for the exhaust control valve 33 via the amplifier circuit 20; (4 is actuated to open the exhaust control valve 33, thereby opening the second branch gripping air path 11.

When the second branch exhaust passage 11 is opened, the exhaust gas flowing down this passage 11 drives the turbine 311 to perform secondary turbocharging. The secondary turbo supercharging and the check valve 32 are opened, and the first and second branch intake passages 5,
A downstream intake passage 2d downstream of the merging section 2a where 6 merges.
A composite pressure of the supercharging pressure given by the primary turbo supercharging and the supercharging pressure given by the secondary turbo supercharging is generated.

Therefore, when the engine 1 is operating at low speed, the primary turbo supercharging is applied, and when the engine 1 is operating at high speed, the combined supercharging pressure provided by the primary and secondary turbo superchargers 30 and 31 is the predetermined maximum supercharging pressure. When the supply pressure is reached, the exhaust pressure increases accordingly and reaches the set value, so the control Guya 7 ram device 2
4 opens the boost pressure control valve 22 to open the exhaust bypass passage 2.
1 and lowering the driving force of the turbines 30b and 31b, the boost pressure can be controlled to be below the maximum boost pressure.

That is, in a type of turbocharged engine that uses both primary and secondary turbocharging 130.31, the control gouya 7 ram 24 is controlled by a signal from a fixed location, regardless of whether it is used alone or in combination. Therefore, the passage resistance of the first and second branch intake passages 5 and 6 and the first and second branch exhaust passages 1o
, 1t, even if there is a difference in the path resistance of Ennon 1
It is possible to effectively and accurately control the maximum boost pressure of the supercharge air supplied to the engine.

Incidentally, in the same way as described for the first embodiment shown in FIG. 1, maximum boost pressure control may be performed using the intake bypass passage 26 also in this second embodiment.

Regarding the following second embodiment, the same reference numerals are given to those parts that are not different from the first embodiment, and redundant explanation will be omitted.

It goes without saying that the present invention can also be applied to a type of turbocharged engine that constantly uses two turbochargers arranged in parallel, regardless of whether the engine speed is low or high. .

As is clear from the above description, according to the present invention, ■;
The amount of supercharged air actually supplied to the engine is independent of the individual characteristics and operating ranges of the turbochargers arranged in the row, as well as the differences in passage resistance of the individual turbochargers. By extracting the supercharging pressure as exhaust pressure upstream of the branch of the wandering passage upstream of the turbine, the maximum supercharging pressure can always be controlled with high precision.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an engine system showing a first embodiment of the present invention, Fig. 2 is an explanatory block diagram of the control circuit of Fig. 1, and Fig. 3 is an explanatory diagram of an engine system showing a second embodiment of the invention. , 4th
The figure is a block diagram of a control circuit similar to that in FIG. 2. 1...Engine 2...Intake passages 5, 6...First and second branch intake passages 2a...Merge portion 3...Exhaust passages 10, 11...First. Second branch exhaust passage 3a...branch portion 8.9...low speed, high speed turbo supercharger 8a, 9a
... Blower, 8b, 91) ... Turbine, 8c,
9c... Rotating shaft 21... Exhaust bypass passage 22... Supercharging pressure control valve 24... Control diaphragm device 25... Exhaust pressure introduction passage

Claims (1)

[Claims] (1) Equipped with a plurality of turbo superchargers each consisting of a turbine driven by engine exhaust gas and a blower connected to the turbine by a rotating shaft; Turbocharging (in a geometric engine, turbocharging is provided in parallel with each turbine in response to the exhaust pressure in the exhaust passage between the branch part of the exhaust passage upstream of each turbine and the engine, and the exhaust pressure exceeds a set value) 1. A supercharging pressure control device for a turbocharged engine, comprising a maximum supercharging pressure control device that limits a maximum boost pressure by lowering exhaust pressure.