JP2004308570A - Hybrid power plant and method of operating the same - Google Patents

Abstract

A hybrid power plant and a method of operating the hybrid power plant that can reliably reduce vibration generated in an internal combustion engine during a compression stroke when the engine is stopped or started.
In a vehicle C equipped with a parallel type hybrid power unit combining an internal combustion engine 1 and motor generators MG1 and MG2, when the internal combustion engine 1 is stopped or started, the intake manifold 4 of the internal combustion engine 1 The engine speed is reduced or increased while the pressure inside the surge tank 10 or the like is reduced.
[Selection] Figure 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a parallel-type hybrid power unit that combines an internal combustion engine and an electric motor, and a method of operating the same.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a so-called parallel type hybrid power device, a device in which two motor generators are coupled to a crankshaft of an internal combustion engine via a damper for attenuating torsional vibration and a planetary gear mechanism has been known ( For example, see Patent Document 1.) In a hybrid power plant including this type of internal combustion engine, it is necessary to avoid resonance of torsional vibration generated on the crankshaft of the internal combustion engine when the internal combustion engine is stopped or started. For this reason, in this hybrid power plant, when the engine is stopped, the electric motor rotates in the opposite direction to the crankshaft of the internal combustion engine with respect to the crankshaft of the internal combustion engine so as to quickly pass through the rotational speed range where torsional vibration resonance is observed. Of torque is applied.
[0003]
Further, as a technique for preventing the resonance of torsional vibration generated in a crankshaft of an internal combustion engine, there is known a technique of adjusting the opening / closing timing of an intake valve so that the effective compression ratio of the internal combustion engine is reduced (for example, see Patent Document 1). 2). As described above, by reducing the effective compression ratio of the internal combustion engine, the torque fluctuation acting on the crankshaft is reduced, and the compression work in the internal combustion engine is reduced. Therefore, according to such a technique, it is possible to reduce the amplitude of the torsional vibration of the crankshaft and quickly pass through the rotational speed range where the resonance of the torsional vibration is recognized.
[0004]
[Patent Document 1]
JP-A-10-306739
[Patent Document 2]
JP-A-10-82332
[0005]
[Problems to be solved by the invention]
However, even if the resonance of the torsional vibration is prevented as described above, even when the internal combustion engine having a low engine speed is stopped or started, particularly in the rotation speed range where the resonance of the torsional vibration is recognized, the internal combustion engine during the compression stroke is not affected. Vibration may occur in the engine. Here, when the above-described parallel type hybrid power unit is applied to a vehicle, the power transmission path from the internal combustion engine to the drive wheels may not be completely cut off. In such a case, during the compression stroke, The vibration generated in the internal combustion engine is transmitted to the drive wheels. The shock resulting from such vibration is perceived as unpleasant by the user of the vehicle equipped with the hybrid power unit.
[0006]
Accordingly, an object of the present invention is to provide a hybrid power plant and a method of operating the hybrid power plant that can surely reduce vibration generated in an internal combustion engine during a compression stroke when the engine is stopped or started.
[0007]
[Means for Solving the Problems]
A hybrid power unit according to the present invention is a parallel type hybrid power unit in which an internal combustion engine and an electric motor are combined. When the internal combustion engine is stopped or started, the rotation speed of the internal combustion engine is reduced while the intake system of the internal combustion engine is depressurized. Is reduced or increased.
[0008]
In this hybrid power unit, when stopping or starting the internal combustion engine, the internal pressure of the intake system is preferably reduced to the atmospheric pressure or less, and the rotational speed of the internal combustion engine is reduced or increased while the internal pressure of the intake system is reduced. Let me do. Thereby, in this hybrid power plant, the amount of air compressed in the combustion chamber during the compression stroke at the time of engine stop or startup can be reduced, and the internal pressure of the combustion chamber during the compression stroke at the time of engine stop or the like can be reduced. Therefore, it is possible to reliably reduce the vibration of the internal combustion engine that occurs during the compression stroke when the engine is stopped or started.
[0009]
Further, when the intake system of the internal combustion engine is depressurized, the throttle valve included in the intake system is fully closed, and the torque from the electric motor to the crankshaft of the internal combustion engine is the same as the rotation direction of the crankshaft. Is preferably added.
[0010]
As described above, by rotating the crankshaft by the electric motor in a state where the supply of further air to the intake system is stopped, the air remaining in the intake system is sucked into the combustion chamber, and the air from the combustion chamber is discharged from the combustion chamber. Since the discharge of air and the like is promoted, the pressure inside the intake system can be quickly reduced.
[0011]
Further, it is preferable that when opening and closing the intake system of the internal combustion engine, the opening and closing timing of the intake valve of the internal combustion engine be advanced.
[0012]
Thus, the intake of air in the intake system into the combustion chamber can be further promoted, so that the internal pressure of the intake system can be reduced to the target value very early.
[0013]
Further, it is preferable that the effective compression ratio of the internal combustion engine be reduced when the rotation speed of the internal combustion engine is reduced or increased.
[0014]
As a result, the torque fluctuation acting on the crankshaft of the internal combustion engine is reduced, and the compression work in the internal combustion engine is reduced. Therefore, the amplitude of the torsional vibration of the crankshaft is reduced, and the rotational speed range where the resonance of the torsional vibration is recognized. Can be passed quickly.
[0015]
Further, when the rotation speed of the internal combustion engine is reduced, it is preferable that a torque is applied from the electric motor to the crankshaft of the internal combustion engine in a direction opposite to the rotation direction of the crankshaft.
[0016]
Thus, when the internal combustion engine is stopped, it is possible to quickly pass through the rotation speed range where torsional vibration resonance is recognized.
[0017]
The method of operating a hybrid power plant according to the present invention is a method of operating a parallel type hybrid power plant in which an internal combustion engine and an electric motor are combined, wherein when stopping or starting the internal combustion engine, the intake system of the internal combustion engine is depressurized, The method is characterized in that the rotation speed of the internal combustion engine is reduced or increased while the pressure in the system is reduced.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a hybrid power plant and an operation method thereof according to the present invention will be described in detail with reference to the drawings.
[0019]
FIG. 1 is a schematic configuration diagram illustrating a vehicle including a hybrid power unit according to the present invention. The hybrid vehicle C shown in FIG. 1 has motor generators MG1 and MG2 in addition to the internal combustion engine 1. In the vehicle C, the internal combustion engine 1 and the motor generator MG2 are mainly used as a driving source for traveling, while the motor generator MG1 is driven by the internal combustion engine 1 and mainly functions as a generator.
[0020]
Here, first, the internal combustion engine 1 included in the vehicle C will be described. The internal combustion engine 1 generates power by rotating a crankshaft S by reciprocating a piston 3 by combustion of a mixture of fuel and air in a combustion chamber 2. Although FIG. 1 shows only one cylinder, the internal combustion engine 1 is preferably configured as a multi-cylinder engine, and the internal combustion engine 1 of the present embodiment is configured as, for example, a four-cylinder engine.
[0021]
An intake port of each combustion chamber 2 is connected to an intake pipe 4a constituting an intake manifold 4, and an exhaust port of each combustion chamber 2 is connected to an exhaust pipe 5a constituting an exhaust manifold 5, respectively. Further, an intake valve Vi for opening and closing an intake port and an exhaust valve Ve for opening and closing an exhaust port are provided for each combustion chamber 2 in a cylinder head of the internal combustion engine 1. Each intake valve Vi and each exhaust valve Ve are opened and closed by a valve mechanism 6 having a variable valve timing function (VVT). Further, a plurality of spark plugs 7 are arranged in the cylinder head of the internal combustion engine 1 so as to face each combustion chamber 2. Each spark plug 7 forms an electric spark by the high voltage applied from the igniter 8 via the distributor 9, and ignites the air-fuel mixture.
[0022]
As shown in FIG. 1, the intake manifold 4 (each intake pipe 4a) is connected to an air supply line 11 via a surge tank 10, and a throttle valve 12 is incorporated in the middle of the air supply line 11. ing. In the present embodiment, an electronically controlled throttle including an actuator (throttle motor) 13 and a throttle opening sensor 14 is employed as the throttle valve 12. Each intake pipe 4a is provided with a fuel injection valve 15 connected to a fuel tank via a fuel pump (not shown). Each fuel injection valve 15 is capable of injecting fuel such as gasoline into the corresponding intake pipe 4a, and the fuel injected by each fuel injection valve 15 mixes with air from the surge tank 10 to form an air-fuel mixture. It is sucked into each combustion chamber 2. On the other hand, the exhaust manifold 5 is connected to a catalyst device (three-way catalyst) 16 as shown in FIG. As the catalyst device 16, any device can be adopted, and an electrically heated catalyst device may be connected to the exhaust manifold 5.
[0023]
As shown in FIG. 1, the internal combustion engine 1 includes an engine electronic control unit (hereinafter, referred to as “engine ECU”) 20 functioning as control means. The engine ECU 20 includes the above-described valve mechanism 6 and igniter 8. , A throttle valve 12 (actuator 13), each fuel injection valve 15, and the like. The engine ECU 20 includes a CPU, a ROM, a RAM, an input / output port, a storage device, and the like, all of which are not shown. Further, the engine ECU 20 is connected to various sensors and the like for detecting the operating state of the internal combustion engine 1. The sensors connected to the engine ECU 20 include a throttle opening sensor 14, a pressure sensor 17 for detecting the internal pressure of the surge tank 10, a water temperature sensor 18 for detecting the engine water temperature, and a rotation speed sensor 9a provided in the distributor 9. And a rotation angle sensor 9b. Further, a cell motor (starter motor) 19 for starting the internal combustion engine 1 is connected to the engine ECU 20, and the control of the cell motor 19 is also executed by the engine ECU 20.
[0024]
As shown in FIG. 1, the crankshaft S of the internal combustion engine 1 is connected to the motor generators MG1 and MG2 via a damper 25 for damping torsional vibration and a planetary gear mechanism 30. The internal combustion engine 1, the planetary gear mechanism 30, and the motor generators MG1 and MG2 constitute a parallel hybrid power unit. The planetary gear mechanism 30 includes a sun gear 31 located at the center, a ring gear 32 provided concentrically outside the sun gear 31, and a plurality of gears that mesh with both the sun gear 31 and the ring gear 32 to revolve around the outer periphery of the sun gear 31 while rotating. , And a planetary carrier 34 that rotatably supports the shaft of each planetary pinion gear 33.
[0025]
Sun gear 31 is connected to motor / generator MG1 via hollow sun gear shaft S1, and ring gear 32 is connected to motor / generator MG2 via ring gear shaft S2. The transmission shaft S3 is fixed to the planetary carrier 34. The transmission shaft S3 is inserted into the sun gear shaft S1 and is connected to the crankshaft S of the internal combustion engine 1 via a damper 25. Further, the ring gear 32 is connected to a differential gear 27 via a chain belt 35 and a power transmission gear 26.
[0026]
The planetary gear mechanism 30 configured as described above has three shafts, i.e., a crankshaft S (transmission shaft S3), a sun gear shaft S1, and a ring gear shaft S2, as power input / output shafts. When the power input / output to the two axes is determined, the power input / output to the remaining axes is determined based on the power input / output to the other two axes. The planetary gear mechanism 30 transmits the output of the motor generator MG2 to the drive wheels W via the chain belt 35, the power transmission gear 26, the differential gear 27, and the like, and outputs the output of the internal combustion engine 1 to the motor generator MG1. And a drive wheel for distributing the drive wheels to the drive wheels W, and a transmission for reducing or increasing the rotation speed of the motor / generator MG2 or the internal combustion engine 1 and transmitting the rotation to the drive wheels W.
[0027]
Motor generators MG1 and MG2 are each configured as an AC synchronous motor operable as both a motor and a generator, and include a rotor 42 having a plurality of permanent magnets 41 on an outer peripheral surface and a three-phase coil 44 forming a rotating magnetic field. And the wound stator 45. The rotor 42 of the motor generator MG1 is fixed to the sun gear shaft S1 of the planetary gear mechanism 30, and the rotor 42 of the motor generator MG2 is fixed to the ring gear shaft S2 of the planetary gear mechanism 30. On the other hand, stators 45 of motor generators MG1 and MG2 are fixed to the inner peripheral surface of casing 40 shared by motor generators MG1 and MG2 and planetary gear mechanism 30, respectively. Further, a resolver R1 for detecting the rotation angle of the rotor 42 of the motor / generator MG1 is provided on the sun gear shaft S1, and a resolver R2 for detecting the rotation angle of the rotor 42 of the motor / generator MG2 is provided on the ring gear shaft S2. Is provided.
[0028]
Motor generator MG1 is connected to a motor electronic control unit (hereinafter referred to as “motor ECU”) 50 via inverter 51, and motor generator MG2 is connected to motor ECU 50 via inverter 52. The motor ECU 50 has a CPU, a ROM, a RAM, an input / output port, a storage device, and the like (not shown), and controls the inverters 51 and 52 so that the three-phase motor generators MG1 and / or MG2 An alternating current having an appropriate current value is supplied to the coil 44 at a predetermined frequency to control the operation of the motor generators MG1 and MG2. In the vehicle C, electric power is supplied from the traveling battery 55 to the starter motor 19 for starting the internal combustion engine 1.
[0029]
The vehicle C includes a hybrid ECU 100 that functions as a control unit for the entire vehicle. The hybrid ECU 100 also has a CPU, a ROM, a RAM, input / output ports, a storage device, and the like (not shown). The input / output ports include an accelerator position sensor 56, a brake position sensor 57, a shift position sensor 58, and an ignition switch. 59 etc. are connected. The hybrid ECU 100 controls the entire vehicle C while exchanging various information with the engine ECU 20 and the motor ECU 50 described above.
[0030]
Next, a stop procedure and a start procedure of the internal combustion engine 1 in the above-described vehicle C (hybrid power unit) will be described.
[0031]
First, the stop procedure of the internal combustion engine 1 in the vehicle C will be described with reference to FIG. 2. When the internal combustion engine 1 is operating in the vehicle C, the hybrid ECU 100 indicates that the user should stop the internal combustion engine 1. It is monitored whether a command has been issued (S10). When a user issues a command to stop internal combustion engine 1, hybrid ECU 100 transmits an engine stop command signal to both engine ECU 20 and motor ECU 50 instantaneously.
[0032]
Upon receiving the engine stop command signal from the hybrid ECU 100, the engine ECU 20 compares the internal pressure of the surge tank 10 detected by the pressure sensor 17 provided in the surge tank 10 with a predetermined value Pr1. (S12). The specified value Pr1 used in S12 is defined as a value smaller than the atmospheric pressure (about 1013 hPa), and is stored in the storage device of the engine ECU 20. In the present embodiment, the specified value Pr1 is, for example, a value that is about half the atmospheric pressure (about 500 hPa).
[0033]
Here, when the internal combustion engine 1 is operating, since a large amount of air is taken into the surge tank 10, the internal pressure of the surge tank 10 generally becomes larger than the specified value Pr1. Therefore, immediately after the engine stop command is issued, it is determined in S12 that the internal pressure of the surge tank 10 is not usually lower than the specified value Pr1. When the engine ECU 20 determines that the internal pressure of the surge tank 10 is not lower than the specified value Pr1, that is, is equal to or more than the specified value Pr1, the engine ECU 20 provides a predetermined command signal to the motor ECU 50 via the hybrid ECU 100, Execute the process.
[0034]
In S14, the engine ECU 20 stops the fuel injection from each of the fuel injection valves 15 and completely closes the throttle valve 12 included in the air supply line 11 constituting the intake system together with the intake manifold 4 and the surge tank 10. Further, the motor ECU 50 that has received the command signal from the engine ECU 20 operates the motor generator MG1 such that the crankshaft S of the internal combustion engine 1 to which the fuel supply has been stopped is rotated in the same direction as the previous rotation direction. The inverters 51 and 52 are controlled according to a predetermined program or the like (S14). Thus, the rotation of ring gear shaft S2 is regulated by motor / generator MG2, and the rotation speed of crankshaft S is maintained at a predetermined target rotation speed NE1 from motor / generator MG1. , A torque in the same direction as the previous rotation direction of the crankshaft S is applied.
[0035]
As described above, the crankshaft S of the internal combustion engine 1 is rotated by the motor / generator MG1 while the supply of further air to the surge tank 10 and the intake manifold 4 is stopped, so that the surge tank 10 and the intake manifold 4 are Since the suction of the air left inside into each combustion chamber 2 and the discharge of the air and the like from each combustion chamber 2 are promoted, the intake system constituted by the surge tank 10 and the intake manifold 4 and the like can be quickly changed. The inside will be depressurized. In the present embodiment, the target rotation speed NE1 is set to a value larger than the resonance rotation speed region of the torsional vibration of the crankshaft S.
[0036]
Further, in S14, the engine ECU 20 gives a predetermined command signal to the valve mechanism 6 to set the advance amount of the opening / closing timing of each intake valve Vi to the maximum. As described above, when the pressure inside the surge tank 10 and the intake manifold 4 is reduced, the opening and closing timing of each intake valve Vi is advanced, so that the intake of air into each combustion chamber 2 can be further promoted. Therefore, the pressure inside the surge tank 10 and the intake manifold 4 can be reduced very early.
[0037]
Then, after the processing in S14, the engine ECU 20 again compares the internal pressure of the surge tank 10 detected by the pressure sensor 17 provided in the surge tank 10 with a predetermined specified value Pr1 in S12. I do. The process of S14 is continued until the engine ECU 20 determines in S12 that the internal pressure of the surge tank 10 has fallen below the specified value Pr1. When determining that the internal pressure of the surge tank 10 has fallen below the specified value Pr1 in S12, the engine ECU 20 gives a predetermined command signal to the motor ECU 50 via the hybrid ECU 100 and executes the process of S16.
[0038]
In S16, the engine ECU 20 stops the fuel injection from each fuel injection valve 15, and keeps the throttle valve 12 completely closed. Further, the motor ECU 50, which has received the command signal from the engine ECU 20, controls the rotation of the ring gear shaft S2 by the motor / generator MG2 and, with respect to the crankshaft S, from the motor / generator MG1 to that of the crankshaft S. The inverters 51 and 52 are controlled in accordance with a predetermined program or the like so that a torque in a direction opposite to the rotation direction is applied.
[0039]
Thereby, in the hybrid power unit of the vehicle C, when the internal combustion engine 1 is stopped, the internal pressure of the intake system such as the surge tank 10 and the intake manifold 4 is reduced to a level below the predetermined value Pr1 below the atmospheric pressure. Therefore, the engine speed is reduced. Therefore, in the hybrid power unit of the vehicle C, the amount of air compressed in each combustion chamber 2 during the compression stroke when the internal combustion engine 1 is stopped is reduced, and the internal pressure of each combustion chamber 2 during the compression stroke when the engine is stopped is reduced. Since the vibration can be reduced, it is possible to reliably reduce the vibration of the internal combustion engine 1 that occurs during the compression stroke when the engine is stopped.
[0040]
That is, according to the present invention, internal combustion engine 1 is connected to motor generators MG1 and MG2 via planetary gear mechanism 30, and the power transmission path from internal combustion engine 1 to drive wheels W cannot be completely cut off. Also in the vehicle C, it is possible to greatly reduce unpleasant shock caused by transmission of the vibration generated in the internal combustion engine 1 during the compression stroke to the drive wheels W. Further, in S16, by applying a torque in the opposite direction to the rotation direction of the crankshaft S from the motor / generator MG1 to the crankshaft S, the rotation speed of the internal combustion engine 1 is quickly reduced and Thus, it is possible to quickly pass through a rotational speed range where torsional vibration resonance is recognized.
[0041]
Further, in S16, the engine ECU 20 gives a predetermined command signal to the valve mechanism 6, and sets the retard amount of the opening / closing timing of each intake valve Vi to the maximum. As a result, in the internal combustion engine 1, the effective compression ratio is reduced when the engine speed is reduced, so that the torque fluctuation acting on the crankshaft S can be reduced and the compression work can be reduced. As a result, it is possible to reduce the amplitude of the torsional vibration of the crankshaft S and to quickly pass through the rotational speed range where the resonance of the torsional vibration is recognized. After the processing of S16, the engine ECU 20 determines whether or not the internal combustion engine 1 has stopped based on the detection value of the rotation speed sensor 9a included in the distributor 9 (S18), and the engine rotation speed becomes zero. At this stage, the process of S16 is stopped, and the engine stop routine of FIG. 2 is terminated.
[0042]
On the other hand, in the vehicle C provided with the hybrid power unit, the internal combustion engine 1 is started according to the procedure shown in FIG.
[0043]
As shown in FIG. 3, when the hybrid ECU 100 is powered on in the vehicle C, the hybrid ECU 100 monitors whether or not the user issues a command to start the internal combustion engine 1 ( S20). Then, when a user issues a command to start internal combustion engine 1, hybrid ECU 100 instantaneously transmits an engine start command signal to both engine ECU 20 and motor ECU 50.
[0044]
Upon receiving the engine start command signal from hybrid ECU 100, engine ECU 20 compares the internal pressure of surge tank 10 detected by pressure sensor 17 provided in surge tank 10 with a predetermined specified value Pr2. (S22). The specified value Pr2 used in S22 is also set as a value smaller than the atmospheric pressure (about 1013 hPa), and is stored in the storage device of the engine ECU 20. In the present embodiment, the specified value Pr2 is set to, for example, a value that is about half the atmospheric pressure (about 500 hPa).
[0045]
Here, when a certain period of time has elapsed while the internal combustion engine 1 is stopped, the internal pressure of the surge tank 10 is generally equal to the atmospheric pressure. Becomes larger than the specified value Pr2. Therefore, immediately after the engine start command is issued, it is determined in S22 that the internal pressure of the surge tank 10 is not usually lower than the specified value Pr2. When the engine ECU 20 determines that the internal pressure of the surge tank 10 is not lower than the specified value Pr2, that is, is equal to or more than the specified value Pr2, the engine ECU 20 provides a predetermined command signal to the motor ECU 50 via the hybrid ECU 100, Execute the process.
[0046]
In S24, the engine ECU 20 stops the fuel injection from each fuel injection valve 15, and keeps the throttle valve 12 completely closed. Motor ECU 50 that has received the command signal from engine ECU 20 controls the rotation of ring gear shaft S2 by motor / generator MG2, and sets crankshaft S of internal combustion engine 1 to a predetermined target rotational speed NE2 by motor / generator MG1. The inverters 51 and 52 are controlled according to a predetermined program or the like so as to be rotated (S24).
[0047]
As described above, the crankshaft S of the internal combustion engine 1 is rotated by the motor / generator MG1 in a state where the supply of air to the surge tank 10 and the intake manifold 4 is stopped, so that the inside of the surge tank 10 and the intake manifold 4 is Since the suction of the remaining air into each combustion chamber 2 and the discharge of the air and the like from each combustion chamber 2 are promoted, the inside of the intake system constituted by the surge tank 10, the intake manifold 4, etc. is quickly reduced. The pressure will be reduced. In the present embodiment, the target rotational speed NE2 is set to a value smaller than the resonance rotational speed range of the torsional vibration of the crankshaft S.
[0048]
Further, in S24, the engine ECU 20 gives a predetermined command signal to the valve mechanism 6 to set the advance amount of the opening / closing timing of each intake valve Vi to the maximum. As described above, when the pressure inside the surge tank 10 and the intake manifold 4 is reduced, the opening and closing timing of each intake valve Vi is advanced, so that the intake of air into each combustion chamber 2 can be further promoted. Therefore, the pressure inside the surge tank 10 and the intake manifold 4 can be reduced very early.
[0049]
Then, after the processing in S24, the engine ECU 20 again compares the internal pressure of the surge tank 10 detected by the pressure sensor 17 provided in the surge tank 10 with a predetermined specified value Pr2 in S22. I do. Then, the process of S24 is continued until the engine ECU 20 determines in S22 that the internal pressure of the surge tank 10 has fallen below the specified value Pr2. When it is determined in S22 that the internal pressure of the surge tank 10 has fallen below the specified value Pr2 in S22, the engine ECU 20 gives a predetermined command signal to the motor ECU 50 via the hybrid ECU 100 and executes the process of S26.
[0050]
Also in S26, the engine ECU 20 stops the fuel injection from each fuel injection valve 15 and keeps the throttle valve 12 completely closed. Further, the motor ECU 50 that has received the command signal from the engine ECU 20 controls the rotation of the ring gear shaft S2 by the motor / generator MG2, and moves the motor shaft from the motor / generator MG1 to the crankshaft S with respect to the crankshaft S. The inverters 51 and 52 are controlled according to a predetermined program or the like so that a torque in the same direction as the rotation direction is applied to increase the number of revolutions of the crankshaft S.
[0051]
As a result, in the hybrid power unit of the vehicle C, when the internal combustion engine 1 is started, the pressure in the intake system such as the surge tank 10 and the intake manifold 4 is reduced to a level lower than a predetermined value Pr2 equal to or lower than the atmospheric pressure. Therefore, the engine speed is increased. Therefore, in the hybrid power unit of the vehicle C, the amount of air compressed in each combustion chamber 2 during the compression stroke at the time of starting the internal combustion engine 1 is reduced, and the internal pressure of each combustion chamber 2 during the compression stroke at the time of engine startup is reduced. Since the vibration can be reduced, the vibration of the internal combustion engine 1 generated during the compression stroke at the time of starting the engine can be reliably reduced.
[0052]
That is, in the vehicle C, even when the internal combustion engine 1 is started, uncomfortable shock caused by transmission of vibration generated in the internal combustion engine 1 during the compression stroke to the driving wheels W can be significantly reduced. . Also, in S26, the torque in the same direction as the rotation direction of the crankshaft S is applied from the motor / generator MG1 to the crankshaft S, so that the rotation speed of the internal combustion engine 1 is increased quickly. Thus, it is possible to quickly pass through a rotational speed range where torsional vibration resonance is recognized.
[0053]
Further, in S26, the engine ECU 20 gives a predetermined command signal to the valve mechanism 6 to set the retard amount of the opening / closing timing of each intake valve Vi to the maximum. As a result, in the internal combustion engine 1, the effective compression ratio is reduced when the engine speed is increased, so that the torque fluctuation acting on the crankshaft S can be reduced and the compression work can be reduced. As a result, it is possible to reduce the amplitude of the torsional vibration of the crankshaft S and to quickly pass through the rotational speed range where the resonance of the torsional vibration is recognized.
[0054]
After the process of S26, the engine ECU 20 causes the rotation speed of the internal combustion engine 1 to exceed the rotation speed range (resonance rotation speed range) where resonance of torsional vibration is recognized based on the detection value of the rotation speed sensor 9a included in the distributor 9. Is determined (S28), and the process of S26 is stopped when the engine speed exceeds the resonance speed range. Then, the ECU 20 terminates the engine start routine of FIG. 3 and shifts to the processing during normal operation.
[0055]
In the vehicle C, if the engine start command is issued within a very short time after the internal combustion engine 1 is temporarily stopped according to the procedure shown in FIG. Since the pressure is reduced to about the specified value Pr1, it is not particularly necessary to start the internal combustion engine 1 according to the procedure shown in FIG.
[0056]
【The invention's effect】
As described above, according to the present invention, it is possible to reliably reduce the vibration generated in the internal combustion engine during the compression stroke when the engine is stopped or started.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a vehicle provided with an internal combustion engine according to the present invention.
FIG. 2 is a flowchart illustrating a procedure for stopping an internal combustion engine in the vehicle of FIG. 1;
FIG. 3 is a flowchart illustrating a procedure for starting an internal combustion engine in the vehicle of FIG. 1;
[Explanation of symbols]
1 Internal combustion engine
2 Combustion chamber
4 Intake manifold
6 Valve train
10 Surge tank
11 Air supply line
12 Throttle valve
15 Fuel injection valve
17 Pressure sensor
20 Engine ECU
30 planetary gear mechanism
50 Motor ECU
51,52 Inverter
100 Hybrid ECU
C hybrid vehicle
MG1, MG2 motor generator
S crankshaft
Vi intake valve
W drive wheel

Claims (6)

In a parallel type hybrid power unit combining an internal combustion engine and an electric motor,
When the internal combustion engine is stopped or started, the rotation speed of the internal combustion engine is reduced or increased while the intake system of the internal combustion engine is depressurized. When depressurizing the intake system of the internal combustion engine, the throttle valve included in the intake system is fully closed, and the rotation direction of the crankshaft from the electric motor to the crankshaft of the internal combustion engine is the same. The hybrid power plant according to claim 1, wherein the torque of (i) is applied. 3. The hybrid power plant according to claim 2, wherein when depressurizing the intake system of the internal combustion engine, the opening / closing timing of an intake valve of the internal combustion engine is advanced. 4. The hybrid power plant according to any one of claims 1 to 3, wherein the effective compression ratio of the internal combustion engine is reduced when the rotation speed of the internal combustion engine is reduced or increased. 5. The motor according to claim 1, wherein when the rotation speed of the internal combustion engine is reduced, a torque in a direction opposite to a rotation direction of the crankshaft is applied from the electric motor to a crankshaft of the internal combustion engine. 6. The hybrid power plant according to any one of the above. In a method of operating a parallel-type hybrid power unit that combines an internal combustion engine and an electric motor,
When the internal combustion engine is stopped or started, the intake system of the internal combustion engine is depressurized, and the rotation speed of the internal combustion engine is reduced or increased while the interior of the intake system is depressurized. An operation method of the hybrid power plant.

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