JP2932187B2 - Control device for engine with mechanical supercharger - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device for an engine having a mechanical supercharger driven by an engine output.

(Prior Art) Conventionally, a mechanical supercharger driven by a driving force of an engine output shaft is provided, and in a low-load and low-rotation state, driving loss is reduced and fuel efficiency is improved. Japanese Patent Application Laid-Open No. Sho 59-60029 and Japanese Utility Model Application Laid-open No. Sho 62-111938 disclose a technique in which the drive of the engine is stopped and a passage for supplying intake air is bypassed to the turbocharger. It is known as such.

The supercharging bypass passage is low-speed when the supercharger is not driven, and supplies the intake air in a fully open state in a low-load state, while the engine speed and the load are increased and the supercharger is driven, The opening and closing control is performed so as to gradually close and increase the supercharging pressure.

As the mechanical supercharger, various types have been proposed and put into practical use, such as those based on a roots blower system and those using an internal compression system such as a screw system.

(Problems to be Solved by the Invention) However, in the above-described engine with a mechanical supercharger, the opening degree of the supercharging bypass passage is adjusted according to the engine speed or the load. When the supply bypass air passage diameter is the same, the pressurized air discharged from the supercharger increases as the rotation speed increases, and excess air passes through the supercharge bypass passage. And the pressure downstream of the supercharger rises. As a result, the amount of air introduced into the cylinder increases, the engine output increases, and when trying to obtain the same torque,
The throttle valve will be further throttled. Then, the pressure on the upstream side of the turbocharger decreases and the pressure difference between the front and rear of the turbocharger increases, and the work amount of this supercharger is determined by the front and rear pressure difference.
The supercharger drive loss increases, and particularly in the case of an internal compression type supercharger, the pump work is large, resulting in a decrease in fuel efficiency due to an increase in drive loss.

By the way, in order to drive the mechanical supercharger and control it by the amount of air that bypasses the supercharger so that the engine load becomes a predetermined state, the bypass amount is increased as the engine speed increases, and the supercharger is increased. It is necessary to return the air discharged from to the upstream side.

In addition, when driving by switching the connection of the mechanical supercharger in the load direction to the low and middle rotation range, in order to reduce the torque fluctuation corresponding to the driving resistance, it is necessary to narrow the bypass passage and increase the engine load. preferable. On the other hand, as described above, as the engine speed increases and the load decreases, the flow area of the bypass passage needs to be increased to increase the flow air amount, and the torque at the time of switching the connection of the supercharger is required. Unlike the requirement for the amount of bypass air to reduce fluctuations, if any requirement is met, the other will be unsatisfactory. In particular, when the supercharger is in a connected state in a high-rotation state in a low-load region and the supercharge bypass passage is narrowed, there is a problem that the driving load of the supercharger increases.

In view of the above circumstances, the present invention is designed to reduce the driving load of the turbocharger at low load and high rotation by adjusting the flow area of the bypass passage accompanying the switching of the connection state of the mechanical supercharger. It is an object of the present invention to provide a control device for a supercharged engine.

In order to achieve the above object, a control apparatus for an engine with a mechanical supercharger according to claim 1 of the present invention provides a control device for an engine with a mechanical supercharger in an operating region where the engine speed is equal to or higher than a predetermined speed. In a mechanically-charged engine provided with a supercharging bypass passage for bypassing the mechanical supercharger while providing a coupling means for coupling to the output shaft to perform supercharging, a flow area of the supercharging bypass passage is provided. A passage adjusting means for adjusting
Based on the change in the connection state of the supercharger accompanying the change in the engine speed by the connecting means exceeding the predetermined speed, the flow area of the supercharging bypass passage to the passage adjusting means is set to It is configured to be set to be large at the time of connection, and to have a control means for setting the ratio of increasing the flow area of the supercharging bypass passage at the time of connection from the time of non-connection of the mechanical supercharger to be larger as the load is lower. is there.

Further, the control device for an engine with a mechanical supercharger according to claim 2 of the present invention connects the mechanical supercharger to the engine output shaft in an operating region where the engine rotational speed is equal to or higher than a predetermined rotational speed. In a mechanical supercharged engine provided with a supercharging bypass passage for bypassing the mechanical supercharger while having a connecting means for supercharging, a passage adjustment for adjusting a flow area of the supercharge bypass passage. Means for controlling the flow area of the supercharging bypass passage with respect to the passage adjusting means based on a change in the connection state of the supercharger caused by a change in the engine speed exceeding the predetermined speed by the connecting means. The control device is configured to be set to be larger at the time of connection than at the time of connection, and to have a control means for setting the flow area of the supercharging bypass passage to be larger at higher rotations.

(Operation) In the control device for an engine with a supercharger as described above, the supercharger is performed by connecting the mechanical supercharger to the engine output shaft in an operation region where the engine speed is equal to or higher than a predetermined speed.
The flow area of the supercharging bypass passage that bypasses the mechanical supercharger is adjusted in accordance with the change in the connection state, and the flow area is controlled by the control means from the time when the mechanical supercharger is not connected to the time when the mechanical supercharger is connected. In a state where the supercharger is connected and the supercharger is connected but the supercharger is not substantially supercharged, the supercharger bypass passage is set at a high speed due to an increase in the engine speed in a low load state. The flow area is increased to reduce the pressure difference before and after the turbocharger, thereby reducing the driving load.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

Embodiment 1 FIG. 1 shows a schematic configuration of an engine with a mechanical supercharger of this embodiment.

In the intake passage 2 for supplying intake air to the cylinder 1a of the engine 1, an air cleaner 3, an intake air sensor 4, and a throttle valve 5 are interposed from the upstream side, and a mechanical supercharger 6 is disposed downstream of the throttle valve 5. Have been. For example, the mechanical supercharger 6 is configured such that two screw-shaped rotors 6a are combined in a state where their respective protrusions and recesses are meshed with each other and rotate in the opposite direction, and between the recesses of the rotor 6a and the inner wall of the casing. As the space moves in the axial direction, the volume of the space gradually decreases,
2. Description of the Related Art An internal compression type supercharger of a screw type (Richorom type) which compresses air inside and pressure-feeds the air is used.

Further, an intercooler 8 is interposed in the intake passage 2 on the downstream side of the mechanical supercharger 6, and a downstream side of the surge tank 7 is formed in an independent intake passage 2a connected to each cylinder 1a. An injector 9 for injecting fuel into the passage 2a is provided.

Further, the turbocharger 6 is bypassed to bypass the supercharger bypass passage.
A first supercharging bypass valve 12 that opens and closes in accordance with the intake pressure downstream of the throttle valve 5 is interposed in the supercharging bypass passage 11. The supercharging bypass passage 11
Has one end connected upstream of the supercharger 6 and downstream of the throttle valve 5, and the other end connected to the downstream of the intercooler 8. The first supercharging bypass valve 12 provided in the supercharging bypass passage 11 includes a valve body 12a for opening and closing the passage and a diaphragm actuator 12b for lifting the valve body 12a, and a pressure chamber 12c of the actuator 12b. When the intake pressure downstream of the throttle valve 5 is introduced through the pressure introduction passage 13 and the intake pressure (negative pressure) increases beyond the set load of the spring 12d, the opening corresponding to the magnitude of the negative pressure is increased. And the opening operation of the supercharging bypass passage 11 is performed.

In the supercharger 6, a driving force from a pulley 17 of an engine output shaft 16 is transmitted via a belt 18 by a pulley 15 having an electromagnetic clutch 14 as a connecting means E, and a control means 20 (controller ) Is output, and the connection between the supercharger 6 and the engine 1 is controlled to perform the drive control.

A throttle bypass passage 21 is provided to bypass the throttle valve 5 and connect the intake passage 2 upstream and downstream of the throttle valve 5. In the middle of the throttle bypass passage 21, a linear solenoid for adjusting the amount of air flowing through the passage 21 is provided. The throttle bypass valve 22 is interposed. A control signal for controlling the idle speed is output from the control means 20 to the throttle bypass valve 22.

Further, a second supercharging bypass valve 24 as a passage adjusting means F is interposed in the supercharging bypass passage 11 in series with the first supercharging bypass valve 12. The second supercharging bypass valve 24 includes a valve element 24a for opening and closing the passage, and a solenoid actuator 24b for driving the valve element 24a to open and close, and controls the solenoid actuator 24b to adjust the opening from the control means 20. A signal is output. The substantial passage area of the supercharging bypass passage 11 is defined by the smaller opening area of the first supercharging bypass valve 12 or the second supercharging bypass valve 24.

The control means 20 includes an intake air amount signal from an intake air amount sensor 4 for detecting an intake air amount, an engine speed and an engine speed in order to control the connection operation of the electromagnetic clutch 14 and the opening degree of the second supercharging bypass valve 24. , An engine speed signal from a rotation sensor 25 for detecting the throttle valve, a throttle opening signal from a throttle sensor 26 for detecting the opening of the throttle valve 5, a water temperature signal from a water temperature sensor 27 for detecting the temperature of the engine cooling water, and the like. Is done.

The control means 20 determines the operating area (see FIG. 4) of the electromagnetic clutch 14 corresponding to the current operating state based on the engine load (for example, throttle opening) and the engine speed, and sets the electromagnetic clutch 14 The opening degree of the second supercharging bypass valve 24 is obtained by comparison with a set rotation number corresponding to the engine rotation number to be switched to the connection state, and a corresponding control signal is output to control the drive of the supercharger 6 and perform the second supercharging. It controls the opening and closing of the bypass valve 24. In particular, the second supercharging bypass valve corresponds to the connection state of the supercharger 6 in a low load range.
The opening degree of 24 is controlled to be larger at the time of connection than at the time of non-connection.

The processing of the control means 20 will be described with reference to the flowcharts of FIGS. FIG. 2 shows the electromagnetic clutch 14
After the control is started, the engine speed N and the intake air amount Q are read in step S1. Then, based on a map of the engine load TVO (throttle opening) and the engine speed N as shown in FIG. 4, it is determined in step S2 whether or not the current operating state is in the ON region II of the electromagnetic clutch 14. .

In the setting example of the control area corresponding to the engine load TVO and the engine speed N shown in FIG. 4, the off-area I of the electromagnetic clutch 14, that is, the non-supercharging area where the supercharger 6 is in the non-driving state, is the engine speed. N is a low-speed low-load region where the engine load TVO is equal to or less than the set value A and the engine load TVO is equal to or less than the set line A,
The other high-rotation high-load region is the ON region II, that is, the supercharging region in which the supercharger 6 is driven.

If the determination in step S2 is YES and the detected operation state is in the ON region II of the electromagnetic clutch 14, the process proceeds to step S3, where the electromagnetic clutch 14 is turned on to establish the connection state, and the drive of the mechanical supercharger 6 is performed. To start. In a state where supercharging is performed by driving the supercharger 6, the first supercharging bypass valve 12 acts to gradually increase the supercharging pressure as the intake pressure downstream of the throttle valve 5 increases. .

The opening of the first supercharging bypass valve 12 depends on the engine load.
It changes with respect to TVO as shown by the solid line V1 in FIG. 5, and is fully opened in a low load state and gradually closed by an increase in load. When the load TVO is equal to or greater than the load Ao that matches the load setting line A, the electromagnetic clutch 14 is connected to the ON state,
In the lower load state (low rotation), the non-connection operation is performed in the off state.

On the other hand, if the determination in step S2 is NO and the state changes to the off region I of the electromagnetic clutch 14, the electromagnetic clutch 14 is turned off in step S4, and the mechanical supercharger 6 is not driven. In this state, the first supercharging bypass valve 12 is opened by the introduction of the intake negative pressure, and the intake air is supplied to the cylinder through the supercharging bypass passage 11.

The load setting line A in FIG.
When the supercharging bypass valve 24 is at a set opening a at the time of non-connection, which will be described later, the passage area of the supercharging bypass passage 11 is constant, and the load is set to a constant torque with little torque fluctuation. The reason why the load setting line A is curved is that the throttle opening TVO is used as the load, and the load setting line A is linear with respect to the load amount such as the boost signal or the filling amount (Q / N). Becomes

Next, FIG. 3 shows an opening / closing operation routine of the second supercharging bypass valve 24. After the control is started, the engine speed N is read in step S5, and in step S6 whether the engine speed N is higher than the set value N1. Determine whether or not. If the determination is YES and the engine speed N is higher than the set value N1, the process proceeds to step S7, where the second supercharging bypass valve
24 is fully opened, while the determination in step S6 is NO.
In step S8, the second supercharging bypass valve 24 is closed to the predetermined opening a in step S8.

The set value N1 of the engine speed in step S5
As shown in FIG. 4, is set to a value equal to or slightly larger than the set value No of the engine speed for partitioning the on / off region of the electromagnetic clutch 14. Therefore, at the time of high rotation in step S7, the electromagnetic clutch 14 is in the on state of the connected state, and at the time of low rotation in step S8, the electromagnetic clutch 14
Corresponds to an uncoupled state that has been turned off.

Accordingly, the opening degree of the second supercharging bypass valve 24 is fully opened in the connected state higher than the set rotation speed N1, regardless of the engine load TVO, as shown by chain lines V2u and V2d in FIG. It closes to a predetermined opening degree a in the following non-connection area. The predetermined opening a is set to coincide with the opening of the first supercharging bypass valve 12 at a value Ao corresponding to the set load line A at which the electromagnetic clutch 14 is turned on in response to a load change. With the above setting, in the low load area below the load value Ao,
The passage area is defined by the opening degree a of the second supercharging bypass valve 24 in a low rotation region where the engine speed N is equal to or less than the set value N1, and the first supercharging bypass is set in a rotation region where the engine speed N is higher than the set value N1. The passage area is defined by the opening of the valve 12. In a high load region equal to or greater than the load value Ao, the passage area is defined by the opening degree of the first supercharging bypass valve 12 which is gradually closed according to the load TVO, regardless of the opening degree of the second supercharging bypass valve 24. You.

To explain the operation of the above embodiment, when the electromagnetic clutch 14 is in the off state in the low-load low-speed range and the mechanical supercharger 6 is not driven, the passage area of the supercharging bypass passage 11 is the second supercharging. The supercharging bypass air is defined by the degree of opening a of the bypass valve 24. The supercharging bypass air is slightly throttled, and an amount necessary for intake is supplied to the engine. 14 turns on and the turbocharger 6
This serves to reduce the torque fluctuation at the start of the driving of. On the other hand, when the engine speed rises higher than the set value N1 from the low load low speed state, the electromagnetic clutch 14
Is turned on to start the operation of the supercharger 6, but at this time, the passage area of the supercharge bypass passage 11 becomes large when the second supercharge bypass valve 24 is fully opened and the mechanical supercharger is opened. The discharge air increased by the high rotation drive of the compressor 6 returns to the upstream side of the supercharger through the supercharge bypass passage 11, and acts to reduce the pressure difference between the front and the rear of the supercharger 6 to reduce the increase in the driving load. . Further, when the load is increased, the supercharging bypass passage 11 is closed by the first supercharging bypass valve 12, which acts to increase the supercharging pressure.

In particular, when the mechanical supercharger 6 is an internal compression type supercharger as in the above embodiment, the driving load is large by the work of the internal compression, and the driving loss at low load and high rotation is remarkable. Therefore, the above-described control for reducing the driving load by increasing the amount of bypass air is effective.

Embodiment 2 The overall configuration of this embodiment is shown in FIG. 6. In this embodiment, a supercharging bypass passage is provided in two systems as compared with the previous embodiment, so that the change range of the control characteristic of the amount of bypass air is increased. is there.

That is, the first supercharging bypass passage 11 and the second supercharging bypass passage 31 that bypass the mechanical supercharger 6 are installed in parallel. The first supercharging bypass passage 11 is provided with the same first supercharging bypass valve 12 that opens and closes in accordance with the intake pressure downstream of the throttle valve 5. A second supercharging bypass passage 32 is interposed in the second supercharging bypass passage 31. The second supercharging bypass valve 32 has a valve element 32a that is opened and closed by a diaphragm actuator 32b, and is provided in the valve closing direction. Pressure chamber 32c with compressed spring 32d compressed
A three-way solenoid valve 34 is interposed in a pressure introduction passage 33 for introducing the intake pressure downstream of the throttle valve 5. A control signal is output from the control means 20 to the three-way solenoid valve 34, and the passage adjusting means F for adjusting the passage area so that the intake pressure (opening operation) and the air introduction (fully closed) are applied to the actuator 32b. ′ Are configured.

A control signal is output from the control means 20 to the three-way solenoid valve 34 of the second supercharging bypass valve 32 when the engine speed N becomes equal to or higher than the set value N1 similar to the previous example, thereby controlling the intake pressure. It is set so as to be introduced into the actuator 32b to open the second supercharging bypass valve 32.

In the above configuration, the supercharging bypass air amount (bypass passage area) that bypasses the mechanical supercharger 6 is determined by the area of the first supercharging bypass passage 11 opened by the first supercharging bypass valve 12, It is defined by the sum of the area of the second supercharging bypass passage 31 opened by the second supercharging bypass valve 32.

The other connecting means E and the like are the same as those in the previous example. In FIG. 6, the same reference numerals are given to the same structures as those in the previous example, and description thereof will be omitted.

FIG. 7 shows changes in the opening degree V1 (solid line) of the first supercharging bypass valve 12 and the opening degree V2 (dashed line) of the second supercharging bypass valve 32 with respect to the load.
In the low-load state, the intake negative pressure downstream of the throttle valve 5 is large in the low load state, so that the full-open state is opened. As the load increases, the intake negative pressure decreases, and the opening degree of the bypass valves 12, 32 gradually increases. It changes to decrease. The two supercharging bypass valves 12 and 32 have different spring characteristics so that the second supercharging bypass valve 32 is set to be fully closed under a lower load condition. When the control signal is actually output to the three-way solenoid valve 34 and the second supercharging bypass valve 32 is in the operating state, the sum of the opening degrees of the two bypass valves 12 and 32 is indicated by a chain line V. It operates with such characteristics that it opens greatly at a low load, sharply decreases as the load increases, and gradually closes after the second supercharging bypass valve 32 is fully closed.

Further, due to the above characteristics, the ratio of increasing the supercharging bypass passage area at the time of connection from the time at which the electromagnetic clutch 14 is not connected is as follows:
It is set to increase as the load decreases.

FIG. 8 shows the operating range of the electromagnetic clutch 14 with respect to the engine load Q / N and the rotational speed, and the set rotational speed N1 for operating the second supercharging bypass valve 32. The low load state in which the rotation is low and the load is equal to or less than Lo is the off region I of the electromagnetic clutch 14, and the other high load and high rotation regions are the on region II of the electromagnetic clutch 14.
The operating speed N1 of the second supercharging bypass valve 32 is set to a speed equal to or slightly higher than the switching speed No of the electromagnetic clutch 14.

In the present embodiment, in the low rotation state where the electromagnetic clutch 14 is in the off region I, the second supercharging bypass valve 32
In the fully closed state, the entire supercharging bypass passage area reduces the torque fluctuation only by the operation of the first supercharging bypass valve 12. When the engine speed N increases, the on-region II of the electromagnetic clutch 14 is reduced. As a result, the driving of the supercharger 6 is started, and the supercharging bypass passage area is increased by the opening operation of the second supercharging bypass valve 32, so that the driving load of the supercharger 6 is reduced. Further, when the load increases, the supercharging bypass passages 11 and 31 close according to the load, and the engine output is increased by increasing the supercharging pressure.

Third Embodiment Although the specific structure of this embodiment is not shown, a linear solenoid valve capable of continuously adjusting the opening degree is used instead of the first supercharging bypass valve 12 and the second supercharging bypass valve 24 in FIG. A single supercharging bypass valve is interposed in the supercharging bypass passage 11 as the passage adjusting means F, and the supercharging bypass valve is opened at a predetermined opening in accordance with a control signal from the control means 20 according to the engine load and the number of revolutions. This is an example of controlling each time.

The control characteristics in this example will be described with reference to FIGS. 9 and 10. The characteristics of the supercharging bypass passage area with respect to the load TVO shown in FIG. 9 are such that the bypass passage area is increased in a low load state and gradually closed as the load increases, and the bypass passage increases as the engine speed N increases. The area is set to be large. In other words, the driving load of the turbocharger increases as the engine speed increases even under the same load condition, and the drive loss of the turbocharger is reduced, so that the bypass passage area is increased in a range where the required supercharging pressure can be obtained.

Also, the engine load TVO (throttle opening) in Fig. 10
And the rotational speed N, the off-region I of the electromagnetic clutch 14 is set in the low-load low-rotation region, and the supercharging bypass passage area decreases as the load TVO increases. The area is set so as to increase as the engine speed N increases. And the electromagnetic clutch
When the engine speed N increases in the same load state from the off-region I of 14, the supercharging bypass passage area is set to be larger in the connected state than in the unconnected state of the electromagnetic clutch 14.

(Effect of the Invention) According to the present invention as described above, the flow area of the supercharge bypass passage that bypasses the mechanical supercharger according to the connection state of the mechanical supercharger corresponding to the change in the engine speed. By adjusting the flow area by the control means so as to be larger at the time of connection than at the time of non-connection of the mechanical supercharger, the demand for supercharging is low and the drive loss of the mechanical supercharger is increased. In a low-load, high-speed state, the drive area can be reduced by reducing the pressure difference before and after the turbocharger by increasing the flow area of the turbocharger bypass passage, and the function of the mechanical turbocharger can be fully exhibited. It is.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a control device for an engine with a mechanical supercharger according to a first embodiment of the present invention, FIG. 2 and FIG. 3 are flow chart diagrams for explaining processing by control means, FIG. FIG. 5 and FIG. 5 are characteristic diagrams showing control characteristics. FIG. 6 is an overall configuration diagram of a control device for a mechanical supercharged engine according to a second embodiment of the present invention. FIG. 7 and FIG. FIG. 9 and FIG. 10 are characteristic diagrams showing control characteristics in the second embodiment, and FIG. 9 and FIG. 10 are characteristic diagrams showing control characteristics in the third embodiment. 1 ... Engine 2 ... Intake passage 5 ... Throttle valve 6 ... Mechanical supercharger 11,31 ... Supercharge bypass passage 12,24,32 ... Supercharge bypass valve 14 ... Electromagnetic clutch, 16 ... Engine output shaft, 20 ... Control means, E ...
Connecting means, F ... passage adjusting means.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hidefumi Fujimoto 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Pref. Mazda Co., Ltd. (56) References Real Opening Sho 61-14725 (JP, U) Field (Int.Cl. ⁶ , DB name) F02B 33/00

Claims (2)

(57) [Claims] 1. A mechanical supercharger is connected to an engine output shaft in an operating region where an engine rotational speed is equal to or higher than a predetermined rotational speed, and a coupling means for supercharging is provided, while the mechanical supercharger is bypassed. In a mechanical supercharged engine provided with a supercharging bypass passage, a passage adjusting means for adjusting a flow area of the supercharging bypass passage, and an engine rotation speed of the connecting means changes beyond the predetermined rotation speed. Based on the change in the connection state of the turbocharger, the flow area of the supercharging bypass passage is set to be larger in the connection of the supercharger bypass passage than in the non-connection state, and the non-connection of the mechanical supercharger is determined. A control device for an engine with a mechanical supercharger, comprising: control means for setting a rate of increasing the flow area of the supercharging bypass passage at the time of connection from the time of connection to a greater value at a lower load. And a connecting means for connecting a mechanical supercharger to an engine output shaft to perform supercharging in an operation region in which the engine rotational speed is equal to or higher than a predetermined rotational speed, while bypassing the mechanical supercharger. In a mechanical supercharged engine provided with a supercharging bypass passage, a passage adjusting means for adjusting a flow area of the supercharging bypass passage, and an engine rotation speed of the connecting means changes beyond the predetermined rotation speed. Based on the change in the connection state of the turbocharger, the flow area of the supercharging bypass passage is set to be larger in the passage adjusting means than in the non-connection state when the connection is made, and the flow area of the supercharging bypass passage is set. A control device for a mechanically-charged engine with a supercharger, comprising: a control means for setting a larger value at a higher rotation speed.