JP5045510B2 - Control device for an internal combustion engine with a supercharger - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine with a supercharger, and more particularly to a device that controls supply of lubricating oil when the supercharger is in a high-speed rotation state for supercharging operation.

  In an internal combustion engine with a supercharger, in order to improve the response to an acceleration request, it is necessary to quickly change the rotation state of the supercharger to a high speed rotation state for supercharging operation.

Patent Document 1 discloses an internal combustion engine that constitutes a parallel twin turbo system in which a secondary turbo supercharging operation is switched between an on state and an off state according to an operating state such as an engine speed. In this internal combustion engine, even when the supercharging operation of the secondary turbo is in the off state, the secondary turbo is in the low speed rotation state. By maintaining the rotation state, it is possible to speed up the time required for the high-speed rotation state by switching the supercharging operation of the secondary turbo from the off state to the on state, as compared to the mode in which the rotation is stopped. .
Japanese Utility Model Publication No. 07-25241

  However, as in Patent Document 1, even if the secondary turbo is maintained in a low-speed rotation state as a preliminary rotation, the rotation state of the secondary turbo is excessive due to the rotational resistance caused by the viscous resistance of the lubricating oil interposed in the bearing of the secondary turbo. It is not possible to sufficiently shorten the time for raising to the high speed rotation state for feeding operation.

  Accordingly, an object of the present invention is to provide an apparatus for shortening the time required for the supercharger to be in a high-speed rotation state for supercharging operation in consideration of the viscous resistance of the lubricating oil.

  The control device for an internal combustion engine according to the present invention includes a supercharger having a ball bearing as a bearing, and a lubrication device that supplies lubricating oil to the ball bearing, and sets the supercharger to a high-speed rotation state for supercharging operation. Sometimes, the lubrication device stops or suppresses the supply of lubricant to the ball bearing.

  By temporarily stopping or suppressing the supply of the lubricating oil, the viscous resistance due to the lubricating oil is reduced during that time, and the rotational resistance of the supercharger is reduced. As a result, the supercharger is likely to rotate, and the time required for the supercharger to be in a high-speed rotation state can be shortened. In addition, since the supercharger is provided with a bearing using a ball bearing, the reliability of the bearing is not greatly reduced even if the supply of lubricating oil is temporarily stopped.

  Preferably, the internal combustion engine includes a primary turbo and a secondary turbo that is switched between an on state and an off state of a supercharging operation depending on an operating state, and a ball bearing that stops or suppresses the supply of lubricating oil from the lubricating device is The secondary turbo bearing.

  When switching from single turbo mode to twin turbo mode, the secondary turbo supercharging operation is switched from the off state to the on state, reducing the rotational resistance of the secondary turbo when turning to the high speed rotation state, making it easier to rotate and high speed rotation It becomes possible to shorten the time for setting the state. Thereby, it is also possible to suppress the occurrence of a torque step when the secondary turbo charging operation is switched to the ON state.

  Further, preferably, the lubricating device is in a stopped state or a suppressed state of the supply of the lubricating oil to the ball bearing after a lubricating oil supply control period that starts after the time when the supply of the lubricating oil is stopped or suppressed is elapsed. To release.

  A period (lubricating oil supply control period) for stopping or suppressing the supply of the lubricating oil is set, and the stopped or suppressed state of the lubricating oil supply is canceled in relation to the elapsed time. Thereby, it becomes possible to perform the lubricating oil supply control without providing a state monitoring means for determining whether the stop state or the suppression state is released, such as a rotation speed sensor of the supercharger.

  More preferably, the lubricating oil supply control period is set based on at least one of the acceleration request level, the operation state of the internal combustion engine at the acceleration request time, and the bearing reliability of the ball bearing.

  Accordingly, it is possible to set an optimal lubricating oil supply control period corresponding to the degree of acceleration request and the like.

  Preferably, the lubricating device releases the stopped state or the suppressed state of the supply of the lubricating oil to the ball bearing based on the rotational speed of the supercharger or the outlet pressure.

  When it is determined that the turbocharger speed or the outlet pressure of the turbocharger has reached the predetermined speed required for supercharging or the predetermined outlet pressure, the supply or stop state of the lubricant is released. Is done. As a result, the stop state or the suppression state can be canceled according to the operation state after the supply of the lubricant is stopped or after the suppression.

  As described above, according to the present invention, it is possible to provide an apparatus that shortens the time required for the supercharger to be in a high-speed rotation state for supercharging operation in consideration of the viscous resistance of the lubricating oil.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The internal combustion engine 1 includes a control unit 5, a primary turbo 13, a secondary turbo 14, a lubrication device 20, an engine body 30, a compressor inlet side intake passage 51, a compressor outlet side intake passage 52, a turbine inlet side exhaust passage 72, and a turbine outlet side. An exhaust passage 73 is provided (see FIG. 1).

  The control unit 5 includes a CPU, a ROM that stores a control program, and a RAM that stores various data. The control unit 5 receives signals from various sensors, and outputs control signals to the intake air switching valve 19 and the like to generate internal combustion. It controls each part of the vehicle including the engine 1. In particular, the control unit 5 performs opening / closing control of the oil supply valve 25 and the oil drain valve 26 of the secondary turbo 14 when switching from the single turbo mode to the twin turbo mode.

  During the operation of the internal combustion engine 1, air is sucked into the combustion chamber of each cylinder of the engine body 30 via the compressor inlet side intake passage 51 and the compressor outlet side intake passage 52 (see the thin dotted arrow in FIG. 1). ). The fuel injected from the injector forms an air-fuel mixture with the sucked air. The air-fuel mixture is combusted by ignition of the spark plug based on the ignition signal from the control unit 5. A crankshaft (not shown) rotates by the reciprocating motion of the piston according to the explosive force caused by the combustion of the air-fuel mixture. The exhaust gas generated by the combustion is discharged through the turbine inlet side exhaust passage 72 and the turbine outlet side exhaust passage 73 (see the broken line arrow in FIG. 1).

  The lubricating device 20 includes first and second oil passages 21 and 22, first and second return passages 23 and 24, an oil supply valve 25, and an oil drain valve 26. The first oil passage 21 is a lubricating oil passage that guides the lubricating oil pumped out from an oil pan provided in the engine body 30 by an oil pump (not shown) to the bearing of the primary turbo 13. The second oil passage 22 This is a lubricating oil passage that guides the lubricating oil pumped out of the pan by the oil pump to the bearing of the secondary turbo 14. The first return passage 23 is a lubricating oil passage that returns the lubricating oil that has lubricated the bearing of the primary turbo 13 to the oil pan of the engine body 30, and the second return passage 24 is the lubricating oil that lubricated the bearing of the secondary turbo 14. This is a lubricating oil passage that returns to the oil pan of the engine body 30. The oil supply valve 25 provided on the second oil passage 22 is a valve for adjusting the flow rate of the lubricating oil supplied from the oil pan to the bearing of the secondary turbo 14, and the oil provided on the second return passage 24. The drain valve 26 is a valve that adjusts the flow rate of the lubricating oil returned from the bearing of the secondary turbo 14 to the oil pan. The lubricating device 20 supplies lubricating oil to other parts (not shown) such as a crankshaft. The opening / closing control of the oil supply valve 25 and the oil drain valve 26 will be described later.

  Next, the configuration of each part of the internal combustion engine 1 will be described focusing on the primary turbo 13 and the secondary turbo 14. The primary turbo 13 and the secondary turbo 14 are connected in parallel, and the primary turbo 13 serves as a main turbocharger, and the secondary turbo 14 serves as a sub turbocharger. In the low intake air amount region, the operation is performed in the single turbo mode in which the secondary turbo 14 is not used for supercharging and the primary turbo 13 is used for supercharging. In the high intake air amount region, the primary turbo 13 and the secondary turbo are operated. 14 is operated in the twin turbo mode used for supercharging.

  The primary turbo 13 has a first turbine 13a, a first compressor 13b, and a first shaft 13c, and the secondary turbo 14 has a second turbine 14a, a second compressor 14b, and a second shaft 14c. A ball bearing or a full float type bearing is used for the bearing of the first shaft 13c, and a ball bearing is used for the bearing of the second shaft 14c.

  The inlet sides of the first and second turbines 13a and 14a are connected to a turbine inlet side exhaust passage 72 that communicates with an exhaust manifold (not shown). The outlet sides of the first and second turbines 13a, 14a are connected to a turbine outlet side exhaust passage 73 communicating with an exhaust gas purification catalyst (not shown).

  The inlet sides of the first and second compressors 13 b and 14 b are connected to the compressor inlet side intake passage 51. The compressor inlet side intake passage 51 is provided with an air cleaner (not shown). The outlet sides of the first and second compressors 13b and 14b are connected to a compressor outlet side intake passage 52 communicating with an intake manifold (not shown). The compressor outlet side intake passage 52 is provided with an intercooler (not shown).

  In order to switch between the twin turbo mode and the single turbo mode, that is, to switch the supercharging operation of the secondary turbo 14 between the on state and the off state, the turbine inlet side exhaust passage 72 is provided with the second turbine 14a on the inlet side. 2 An exhaust gas switching valve 31 for switching between blocking and opening the flow of exhaust gas to the turbine 14a is provided, and the engine main body 30 is connected from the second compressor 14b to the outlet side of the second compressor 14b in the compressor outlet side intake passage 52. An intake switching valve 19 is provided for switching between blocking and opening of the air flow to the.

  In order to smoothly switch from the single turbo mode to the twin turbo mode, the compressor inlet side intake passage 51 is provided on the compressor outlet side intake passage 52 between the outlet of the second compressor 14b and the intake air switching valve 19, and the compressor inlet side intake passage 51. An intake bypass passage 53 that communicates is provided. The intake bypass passage 53 is provided with an intake bypass valve 17 that switches between blocking and opening the air flow.

  In the single turbo mode, both the intake switching valve 19 and the exhaust switching valve 31 are closed, but the intake bypass valve 17 is opened, so that the secondary turbo 14 is not used for supercharging. The turbo 13 is activated and used for supercharging. In the twin turbo mode, both the intake switching valve 19 and the exhaust switching valve 31 are opened, but the intake bypass valve 17 is closed, whereby the primary turbo 13 and the secondary turbo 14 are operated and excessive. Used for paying.

  Lubricating oil is supplied to the bearing of the primary turbo 13 and the bearing of the secondary turbo 14 while the internal combustion engine 1 is in operation. However, the lubricating oil supply control period Δt when the single turbo mode is switched to the twin turbo mode, that is, from the time when the control unit 5 gives an instruction to open the exhaust gas switching valve 31 in order to switch to the twin turbo mode. Until the lubricating oil supply control period Δt elapses, the supply of lubricating oil to the bearing of the secondary turbo 14 is stopped. The supply of the lubricating oil is stopped by closing the oil supply valve 25 and the oil drain valve 26.

  When switching from the single turbo mode to the twin turbo mode, the secondary turbo 14 is changed from the low-speed rotation state to the high-speed rotation state necessary for supercharging. When the rotational speed increases, the supply of lubricating oil to the bearing of the secondary turbo 14 is stopped, so that the rotational resistance caused by the viscous resistance of the lubricating oil interposed in the bearing of the secondary turbo 14 is supplied to the lubricating oil. Less than if you are. Therefore, it becomes easy for the secondary turbo 14 to rotate, and the time necessary for setting the high-speed rotation state, that is, the time necessary for increasing the rotational speed of the secondary turbo 14 to a predetermined rotational speed necessary for supercharging is shortened. Therefore, it becomes possible to improve the responsiveness in switching from the single turbo mode to the twin turbo mode (see FIG. 2).

  The lubrication oil supply control period Δt is a time necessary for setting the secondary turbo 14 in a high-speed rotation state, and is a value considering the bearing reliability of a ball bearing used as a bearing of the second shaft 14c, that is, A value equal to or less than the time that does not impair the bearing reliability even if the supply of the lubricating oil is stopped is set. Under the above-described conditions, it is possible to set the lubricating oil supply control period Δt in advance at the time of development of the internal combustion engine 1 or the like. It is desirable to further correct based on the operating state at the time of requesting acceleration. Specifically, when the degree of acceleration demand is large, that is, the accelerator opening is large, the exhaust gas flow rate is larger than when the accelerator opening is small, and the secondary turbo 14 can be brought into a high-speed rotation state in a short time. The oil supply control period Δt is set to a small value. Further, when the operation state at the time of acceleration request is close to the operation state in the switching region (hysteresis region) between the single turbo mode and the twin turbo mode, the exhaust gas flow is large and the secondary turbo 14 is brought into a high speed rotation state in a short time. Therefore, the lubricating oil supply time Δt is set to a small value. For example, the lubricating oil supply time Δt is shorter in the case of the engine speed and torque corresponding to point b than in the case of the engine speed and torque corresponding to point a as shown in FIG. Set to a value. As described above, it is possible to set the optimum lubricating oil supply control period Δt corresponding to the degree of acceleration request and the like.

  Next, the opening / closing control procedure of the oil supply valve 25 and the oil drain valve 26 by the control unit 5 will be described with reference to the flowchart of FIG. Such opening / closing control is performed while the internal combustion engine 1 is operating in the single turbo mode. Note that when the internal combustion engine 1 starts operation, that is, when the opening / closing control is started, both the oil supply valve 25 and the oil drain valve 26 are opened. When the opening / closing control is started, it is determined in step S11 whether or not the control unit 5 has issued an instruction to switch the exhaust switching valve 31 from the closed state to the opened state in order to switch from the single turbo mode to the twin turbo mode. The The switching determination between the single turbo mode and the twin turbo mode is made based on the operating state of the internal combustion engine 1 such as the engine speed and the fuel injection amount.

  If the control unit 5 has not issued an instruction to switch the exhaust gas switching valve 31 from the closed state to the open state, Step S11 is repeated. That is, the open state of the oil supply valve 25 and the oil drain valve 26 is maintained. Therefore, the state where the lubricating oil is supplied to the bearing of the secondary turbo 14 is maintained.

  When the control unit 5 gives an instruction to switch the exhaust gas switching valve 31 from the closed state to the open state, in step S12, based on the degree of acceleration request and the operating state at the time of the acceleration request of the internal combustion engine 1, the lubricating oil A supply control period Δt is set. Further, the oil supply valve 25 and the oil drain valve 26 are closed by the control of the control unit 5. Thereby, supply of the lubricating oil to the bearing of the secondary turbo 14 is stopped. Moreover, measurement of the elapsed time t from the time when the valve is closed is started. In step S13, it is determined whether the elapsed time t is equal to or longer than the lubricating oil supply control period Δt. If not, step S13 is repeated. If the elapsed time t is equal to or longer than the lubricating oil supply control period Δt, the oil supply valve 25 and the oil drain valve 26 are opened in step 15 and the process ends.

  In the internal combustion engine 1 constituting the parallel twin turbo system, when the single turbo mode is switched to the twin turbo mode, the exhaust gas also flows into the second turbine 14a of the secondary turbo 14, and therefore the inlet of the first turbine 13a of the primary turbo 13 The flow rate of the exhaust gas flowing into the engine is reduced. Thereby, the supercharging pressure in the primary turbo 13 is temporarily reduced, and a supercharging pressure step is generated. Since the supercharging pressure step causes the generation of a torque step, it is necessary to raise the supercharging pressure by setting the secondary turbo 14 in the high speed rotation state as soon as possible. In the present embodiment, when switching from the single turbo mode to the twin turbo mode, the supply of lubricating oil to the bearing of the secondary turbo 14 is temporarily stopped, during which time the viscous resistance due to the lubricating oil is reduced, and the rotational resistance of the secondary turbo 14 is reduced. Reduce. As a result, the secondary turbo 14 is easily rotated, the time required for the secondary turbo 14 to be in a high-speed rotation state can be shortened, and the occurrence of a torque step can be suppressed.

  In addition, since the ball bearing is used for the bearing of the second shaft 14c of the secondary turbo 14, even if the supply of the lubricating oil is stopped during the lubricating oil supply control period Δt, the reliability of the ball in the ball bearing Will not drop significantly.

  In addition, a period (lubricant supply control period Δt) for stopping or suppressing the supply of the lubricant is set, and the supply stop state of the lubricant is canceled in relation to the elapsed time t. Thereby, it becomes possible to perform the lubricant supply control without providing a state monitoring unit for determining the release of the stop state, such as a sensor for separately measuring the rotation speed of the secondary turbo 14.

  Further, as a means for suppressing the occurrence of a torque step, it is conceivable to keep the torque substantially constant by increasing the fuel injection amount until the secondary turbo 14 is in a high-speed rotation state, but in this case, the emission deteriorates. There is a fear. However, in this embodiment, the problem of emission deterioration does not occur.

  Further, in the present embodiment, the embodiment is described in which the supply control of the lubricating oil to the bearing of the secondary turbo 14 in the internal combustion engine 1 constituting the parallel twin turbo system is described. However, only one turbo bearing provided in the internal combustion engine is provided. The form which performs supply control of the lubricating oil to may be sufficient. In this case, the time required to increase the turbo rotation speed to a predetermined rotation speed required for supercharging from the supply stop time set after the acceleration request time (lubricant supply control period Δt ) Until the supply of lubricating oil to the turbo bearing is stopped.

  Moreover, although the form which determines cancellation | release of the stop state of supply of the lubricating oil to the secondary turbo 14 based on the elapsed time after supply stop was demonstrated, the rotation speed sensor separately provided in the secondary turbo 14, outlet pressure, etc. It may be a form that makes a determination based on information from the sensor. In this case, when it is determined that the rotational speed of the secondary turbo 14 or the outlet pressure of the secondary turbo 14 has reached a predetermined rotational speed or a predetermined outlet pressure necessary for supercharging, the supply state of the lubricating oil is stopped. Canceled. As a result, the stop state or the suppression state can be canceled according to the operation state after the supply of the lubricant is stopped or after the suppression.

  Further, the mode in which the supply of the lubricating oil to the bearing of the secondary turbo 14 is stopped when switching from the single turbo mode to the twin turbo mode has been described, but the supply of the lubricating oil is suppressed without stopping completely. That is, the supply amount may be reduced. Since the amount of the lubricating oil supplied to the bearing of the secondary turbo 14 is reduced, the viscous resistance due to the lubricating oil is reduced, the rotational resistance of the secondary turbo 14 is reduced, and it becomes easy to rotate.

It is a block diagram of the internal combustion engine in this embodiment. It is a graph which shows the time transition of the rotation speed of the secondary turbo when switching from the single turbo mode to the twin turbo mode. It is an engine full load performance graph. It is a flowchart which shows the stop control procedure of supply of lubricating oil.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 5 Control part 13 Primary turbo 14 Secondary turbo 13a, 14a 1st, 2nd turbine 13b, 14b 1st, 2nd compressor 13c, 14c 1st, 2nd shaft 20 Lubricating device 21, 22 1st, 2nd Oil passages 23, 24 First and second return passages 25 Oil supply valve 26 Oil drain valve 30 Engine body 51 Compressor inlet side intake passage 52 Compressor outlet side intake passage 53 Intake bypass passage 72 Turbine inlet side exhaust passage 73 Turbine outlet side exhaust aisle

Claims (1)

A turbocharger having a ball bearing as a bearing , the primary turbo, and a supercharger having a secondary turbo that can be switched between an on state and an off state of a supercharging operation according to an operation state of the internal combustion engine ;
A lubricating device that supplies lubricating oil to the ball bearing, and includes a lubricating device that stops or suppresses supply of the lubricating oil to the ball bearing when the supercharger is in a high-speed rotation state for supercharging operation. ,
The lubricating device, the inner case combustion engine operating state is close to the operating state in the switching area between the off and on states of the secondary turbo compared to if spaced, pre SL to the secondary turbo baud bearings A control device for an internal combustion engine with a supercharger, characterized in that a lubricant supply control period, which is a period for stopping or suppressing the supply of lubricant, is shortened.

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