JPH0689674B2 - Exhaust turbocharger - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exhaust turbocharger installed in an automobile engine, in particular, a plurality of exhaust passages are provided, and at least one of these passages can be opened and closed. The exhaust turbocharger.

(Prior Art) An exhaust turbocharger uses the energy of exhaust gas discharged from an engine to supercharge intake air,
Although it improves intake charge efficiency or engine output, this type of exhaust turbocharger uses the above engine output when it is applied to an engine with a wide normal operating range such as an automobile engine. There is a drawback that the improvement effect of is obtained only in a limited area. That is,
By setting the dimensions and shape of the exhaust passage and turbine nozzle so that the required boost pressure can be obtained in the high rotation and high output range of an engine with a large amount of exhaust gas, the turbine can be used in the low rotation and low output range with a small amount of exhaust gas. The flow rate of the exhaust gas supplied is slow and the required supercharging pressure cannot be obtained, and the exhaust passage is disconnected so that the required supercharging pressure can be obtained by increasing the flow rate of the exhaust gas in the low rotation and low power range. If the area or the opening area of the turbine nozzle is made small, the exhaust pressure is remarkably increased and the engine output is rather decreased in the high rotation and high output region where the exhaust gas amount is large.

In order to address the above-mentioned drawbacks of the exhaust turbocharger, the exhaust passage for supplying the exhaust gas to the turbine is divided into a plurality of independent passages, as disclosed in Japanese Utility Model Publication No. 60-1230. In addition, some of the passages are provided with an on-off valve for opening and closing the passage. According to this, in the operating region of an engine with a small amount of exhaust gas, the on-off valve is closed and the exhaust gas is supplied to the turbine from only a part of the passage, so that the flow velocity of the exhaust gas is increased and the required supercharging effect is obtained. In addition, in the operating region where the exhaust gas amount is large, the on-off valve is opened and the exhaust gas is supplied to the turbine from all passages, whereby it is possible to prevent the engine output from decreasing due to the increase in exhaust pressure.

However, in such an exhaust turbo supercharger, in order to prevent malfunction due to exhaust pressure in the opening direction when the on-off valve is in the closed state, as employed in the supercharger disclosed in the above publication, The on-off valve may be configured so that the exhaust pressure acts in the closing direction. However, according to such a configuration, the clutch provided in the power transmission system of the engine is released to rapidly accelerate the vehicle, and the transmission is downshifted. There is a problem that the opening operation of the on-off valve becomes difficult when shifting to a region of high rotation and high output side where the opening operation is performed. In other words, during such rapid downshift acceleration, the accelerator pedal is depressed with the clutch disengaged, causing the engine speed to rise rapidly, or when the clutch is engaged after the downshift operation, the engine speed increases rapidly. As a result, the exhaust pressure acting on the on-off valve rises sharply prior to the opening operation of the on-off valve.
As a result, the opening operation of the on-off valve becomes difficult. If the opening / closing valve does not open even after the shift to the high rotation / high power side region, the exhaust pressure is further increased, which causes a malfunction such as engine misfire or knocking. On the other hand, it is sufficient to increase the driving force of the actuator that operates the on-off valve, but in this case, there is a problem that the actuator becomes large and the cost becomes high.

(Object of the Invention) The present invention addresses the above-described problems in an exhaust turbocharger in which at least one of a plurality of exhaust passages is provided with an opening / closing valve that opens against a discharge pressure. When the transmission is downshifted to rapidly accelerate the engine, the opening / closing valve can be reliably opened without increasing the size of the actuator or the like even when the engine speed or exhaust pressure rapidly increases. Accordingly, it is an object of the present invention to prevent an abnormal increase in exhaust pressure due to the opening / closing valve not opening when the operating region of the engine enters the high rotation and high output region, and the engine malfunction associated therewith.

(Structure of the Invention) The exhaust turbocharger according to the present invention is characterized by having the following structure in order to achieve the above object.

That is, at least one of the plurality of exhaust passages is provided with an opening / closing valve that is opened against the exhaust pressure, and the opening / closing valve is opened on the high rotation and high output side of the engine operating region to open on the low rotation and low output side. In an exhaust turbocharger that is closed by means of a clutch release detecting means for detecting a released state of a clutch means provided in a power transmission system for transmitting an output of an engine to driving wheels of the vehicle, and the detecting means. When the clutch release means detects the released state of the clutch means, the correction means is provided to open the on-off valve for a predetermined period even if the operating region of the engine is in the low rotation and low output side region.

According to this structure, when the clutch means is released to perform the downshift operation of the transmission in order to rapidly accelerate the vehicle in the low rotation and low output range of the engine, the on-off valve is opened when the clutch means is released. Will be opened. Therefore, thereafter, even if the engine speed rapidly increases due to the shift down operation of the transmission or the connection operation of the clutch means after the operation, and the exhaust pressure rapidly increases accordingly, the on-off valve is already open. Since the opening operation is started at least, the opening / closing valve is surely opened when the operating region of the engine enters the high rotation and high output region by the operation for the rapid acceleration.

By the way, if the opening / closing valve is opened at the time when the clutch means is released as described above, the opening / closing valve is opened not only when the transmission is downshifted but also when the transmission is upshifted.
However, since the shift-up operation associated with normal acceleration is performed at a time when the engine speed becomes higher than a certain level, that is, after entering the high rotation and high output range, the on-off valve is already open when the clutch means is released, Therefore, even if the control for opening the on-off valve is performed again, there is no particular problem. Further, during a shift-up operation in the low rotation and low output region, that is, in the region where the on-off valve is originally closed, the supercharging effect is reduced due to the opening operation of the on-off valve accompanying the release of the clutch means. When the shift-up operation is performed in the region, it is a case where the engine output is not originally requested, and therefore there is no problem even in this case.

As described above, according to the present invention, at least one of a plurality of exhaust passages is provided with an opening / closing valve that is opened against resistance to exhaust pressure, so that a low rotation and low output of an engine with a small exhaust gas amount is provided. In the region, the opening valve is closed to increase the flow rate of exhaust gas to ensure the required supercharging effect, and in the high rotation and high output region where the amount of exhaust gas is large, the on-off valve is opened to prevent a significant increase in exhaust pressure. In the exhaust turbocharger, the opening / closing valve is opened by a sudden increase in engine speed or exhaust pressure during sudden acceleration of the vehicle due to downshifting of the transmission without the need to increase the size of the actuator. It is possible to avoid the problem that it becomes difficult. As a result, an abnormal increase in exhaust pressure due to the opening and closing operation of the on-off valve in the high rotation and high output range, and a malfunction of the engine associated therewith are prevented.

(Example) Hereinafter, the Example of this invention is described.

As shown in FIG. 1, the engine 1 has an intake passage 4 for supplying the air sucked from the air cleaner 2 to the combustion chamber through the intake ports 3 ... 3 of each cylinder, and the exhaust port 5 from the combustion chamber.
An exhaust passage 6 that guides the exhaust gas discharged to the outside to the outside 5 is provided. The intake passage 4 is provided with a flow rate detector 7 for detecting the intake amount in the upstream portion, a throttle valve 8 and a surge tank 9 in the downstream portion, and the exhaust passage 6 is not shown. An exhaust emission control device and a silencer are provided.

Further, the engine 1 is provided with an exhaust turbocharger 10 across the intake passage 4 and the exhaust passage 6. The supercharger 10 includes a blower 11 arranged in the intake passage 4,
The turbine 12 arranged in the exhaust passage 6 is connected via a turbine shaft 13, and the turbine 12 is driven by the energy of the exhaust gas passing through the exhaust passage 6, so that the blower 11 is moved to the air cleaner 2 described above. The air sucked from is pressurized and supplied to the combustion chamber of each cylinder.

However, in this supercharger 10, the spiral exhaust passage leading to the turbine nozzle 14 opening around the turbine 12 is provided in the main passage 16 and the sub passage 17 by the partition wall 15 provided along the passage direction. An opening / closing valve 18 for opening and closing the passage 17 is provided at the entrance of the sub passage 17 while being divided. The on-off valve 18 is provided so as to receive the exhaust pressure in the exhaust passage 6 in the closing direction, and therefore operates to oppose the exhaust pressure at the time of opening operation, and an actuator for opening and closing the on-off valve 18. 19 are equipped. The actuator 19 is connected to a negative pressure introducing passage 22 led from the surge tank 9 in the intake passage 4 via a check valve 20 and a control valve 21. Then, the control valve 21
When the downstream portions 22a and 22b communicate with each other on the negative pressure introducing passage 22, the surge tank 9 is inserted into the pressure chamber 19a of the actuator 19.
When the negative pressure is introduced from the diaphragm 19b is displaced in the a direction against the spring 19c, the on-off valve 18 is closed via the rod 19d, and the control valve 21 causes the negative pressure introduction passage. The upstream portion 22a of 22 is blocked and the downstream portion 22b
When the valve is communicated with the atmosphere release port 21a, the atmosphere is introduced into the pressure chamber 19a of the actuator 19 and the diaphragm 19b is displaced in the b direction, so that the opening / closing valve 18 is opened. Here, the check valve 20 prevents the positive pressure from flowing into the actuator 19 when the surge tank 9 is in the positive pressure state. Even when the control valve 21 is closed to the atmosphere after the state, the negative pressure trapped between the check valve 20 and the actuator 19 causes the diaphragm 19 of the actuator 19 to be closed.
The b is kept displaced in the a direction.

Further, the exhaust turbocharger 10 is provided with a bypass passage 23 for directly communicating the main passage 16 with a turbine downstream portion of the exhaust passage 6, and an opening portion of the bypass passage 23 to the main passage 16. A bypass valve 24 for opening / closing the bypass valve 24 and an actuator 25 for opening / closing the bypass valve 24 are provided. The pressure chamber 25a of the actuator 25 is connected to a supercharging pressure introducing passage 26 led from the blower downstream portion of the intake passage 4, and when the supercharging pressure exceeds a predetermined value, the diaphragm 25b resists the spring 25c. By displacing in the c direction, the bypass valve 24 is opened. As a result, a part of the exhaust gas flowing into the main passage 16 is directly discharged through the bypass passage 23, the amount of exhaust gas supplied to the turbine 12 is reduced, and the supercharging pressure is reduced accordingly. By doing so, the bypass valve 24 is closed in the d direction, and as a result, the supercharging pressure is maintained at a predetermined value.

In addition to the above-mentioned structure, the exhaust turbocharger is provided with a control signal e to the control valve 21 to introduce a negative pressure or an atmospheric pressure into the actuator 19 to open / close the valve.
A controller 27 for closing or opening the 18 is provided. This control device 27 connects a clutch (not shown) provided in a power transmission system that transmits the intake air amount signal f output from the flow rate detector 7 and the output of the engine 1 to the drive wheels of the automobile, Clutch sensor 28 for detecting the released state
The clutch signal g output from the input terminal is input, and the control signal e is output based on these signals f and g. That is, as shown in FIG. 2, the intake air amount is set to a predetermined value Q _{0 in} the operating region of the engine with the rotation speed and the load as parameters.
When the engine operating condition is on the low rotation and low load side of this line X, that is, when the intake air amount Q indicated by the intake air amount signal f is below a predetermined value Q ₀ , the control valve is controlled by the control device 27. In order to introduce a negative pressure into the actuator 19 (to close the on-off valve 18) with respect to 21, the operating state is on the high rotation and high load side of the line X, and the intake air amount Q is equal to or more than the predetermined value Q _0. At the time of, the control signal e is output so as to introduce the atmospheric pressure into the actuator 19 (to open the on-off valve 18). Then, when a signal indicating the disengagement of the clutch is input as the clutch signal g, the control device 27 determines that the operating state of the engine 1 is on the low rotation / low load side of the line X (the intake air amount Q is a predetermined value). For a predetermined period, the control signal e is output to the control valve 21 so as to open the on-off valve 18 via the actuator 19 even if Q ₀ or less).

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. 3 showing the above operation of the control device 27.

First, the control device 27 reads the actual intake air amount Q on the basis of the intake air amount signal f in step S ₁ of the flowchart, and in step S ₂ , whether the intake air amount Q is below a predetermined value Q ₀ or more, that is, the engine 1 The operating state of the intake air is a constant intake line X shown in FIG.
The low rotation low load side or the high rotation high load side of is determined. When the intake air amount Q is equal to or greater than the predetermined value Q ₀ , a predetermined control signal e is output to the control valve 21 in step S ₃ , and the opening / closing valve 18 is opened via the control valve 21 and the actuator 19. As a result, the exhaust gas flows from both the main passage 16 and the sub passage 17 to the turbine of the supercharger 10 at high rotation and high load with a large amount of exhaust gas.
As a result, the required supercharging effect can be obtained without causing an excessive increase in exhaust pressure. Also,
When the intake air amount Q is less than or equal to the predetermined value Q _{0 and the} clutch is engaged, the control device 27 executes steps S ₂ to S ₄ and S ₅ to control the on-off valve 18 to close. The signal e is output. As a result, the on-off valve 18 is closed and the exhaust gas is supplied to the turbine 12 with the flow velocity increased only from the main passage 16 at the time of low rotation and low load where the exhaust gas amount is small. Will be obtained.

However, when the operating region of the engine 1 crosses the line X in FIG. 2 and shifts from the low rotation / low load side to the high rotation / high load side, when the open / close valve 18 is opened from the closed state, the open / close valve 18 is The opening operation is performed against the exhaust pressure in the exhaust passage 6, but when the transition of the operating region is rapid, the rising speed of the exhaust pressure is fast, and moreover, the opening operation of the on-off valve 18 is started. Is the atmospheric release port 21a of the valve 21 after the control valve 21 is activated.
Since there is a slight time delay from when the atmospheric pressure is introduced to the actuator 19, the opening / closing valve 8 must be opened against a large exhaust pressure. In particular, when performing a shift down operation of a transmission connected to the engine 1 via a clutch to rapidly accelerate the vehicle, the accelerator pedal is depressed with the clutch released, that is, with no load. As a result, the engine speed or exhaust pressure rises rapidly, which makes it difficult to open the on-off valve 18. Therefore, in such a case, the control device 27 controls the opening / closing valve 18 for a predetermined period according to steps S ₄ and S ₆ of the flowchart at the time when the clutch disengagement operation is performed prior to the downshift operation of the transmission. A control signal e for opening the valve is output to open and close the on-off valve 18 before the engine speed or exhaust pressure rises due to the downshift operation.
To open. Therefore, when the exhaust pressure rises, the on-off valve 18 is already open, or at least the atmospheric pressure is introduced into the actuator 19 and the opening operation of the on-off valve 18 is already started. The open / close valve 18 will open reliably even during downshifts due to such sudden acceleration, and problems such as abnormal rise in exhaust pressure due to the open / close valve 18 not opening in the high rotation and high load region can be avoided. Will be done.

If the opening / closing valve 18 is opened when the clutch is released as described above, the opening / closing valve 18 is opened not only when the transmission is downshifted but also when the transmission is upshifted. Normally, the shift-up operation associated with is performed in the high rotation and high-load region, and the on-off valve 18 is originally open, and the shift-up without acceleration is performed without the engine output being required. It does not matter if the supercharging effect drops due to the opening of. In other words, by opening and closing the on-off valve 18 when the clutch is released, there is no adverse effect when the transmission is upshifted, and the on-off valve 18 is reliably protected against a sudden increase in engine speed or exhaust pressure during downshift. It can be opened.

[Brief description of drawings]

1 is a control system diagram, FIG. 2 is a map showing a control region, and FIG. 3 is a flow chart diagram showing control contents. 10 …… Supercharger, 12 …… Turbine, 14 …… Turbine nozzle, 16,17 …… Exhaust passage (16 …… Main passage, 17 …… Sub passage), 18 …… Open / close valve, 27 …… Correction means (Control device), 28
...... Clutch release detection means (clutch sensor).

Claims (1)

[Claims] 1. An at least one of a plurality of exhaust passages is provided with an opening / closing valve that is opened against a discharge pressure, and the opening / closing valve is opened at a high rotation and high output side of an engine operating region and has a low rotation. An exhaust turbocharger that is closed on the low output side, and clutch release detecting means for detecting the released state of clutch means provided in a power transmission system for transmitting the output of the engine to the drive wheels. Exhaust gas, characterized in that when the detection means detects the disengaged state of the clutch means, it has a correction means for opening the on-off valve for a predetermined period even in the operating region on the low rotation and low output side. Turbocharger.