Hybrid vehicle control device

Abstract

To provide a hybrid vehicle control device capable of achieving both enhancement of catalyst warming-up and NV suppression.SOLUTION: When hysteresis torque obtained with an engine rotation stopped is large, a delay amount of an ignition timing of an engine while warming up a catalyst is set larger than that when the hysteresis torque is low. Therefore, the catalyst becomes more likely to be warmed up as the hysteresis torque is increased. When constraint force against NV due to the engine is increased with the delay amount of the ignition timing set large, the constraint force to be transmitted to a power transmission system with the large hysteresis torque is likely to be damped and thereby causing the NV to be easily suppressed. Thus, a hybrid vehicle control device is capable of achieving both enhancement of catalyst warming-up and NV suppression.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a control device for a hybrid vehicle provided with a damper provided in a power transmission path between an engine and an electric motor.

Background Art

[0002] A control device for a hybrid vehicle including an engine, an electric motor power-transmissively connected to a power transmission path between the engine and drive wheels, and a damper provided between the engine and the electric motor in the power transmission path is well known. For example, the vehicle control device described in Patent Document 1 is such a device. Patent Document 1 discloses that, with the rotation of the crankshaft of the engine locked, torque is applied to the damper by power running control of the electric motor to measure the torsional angle of the damper, and thus a hysteresis torque, which is the difference in torque input to the damper when the torsional angle increases and decreases, is obtained.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, in engine control, when warming up a catalyst provided in the exhaust pipe of the engine, a technique of retarding the ignition timing of the engine is well known as compared with normal operation in which the warming up of the catalyst is completed. The greater the amount of retard during catalyst warm-up, the more the catalyst warm-up is promoted. However, the greater the amount of retard, the more unstable the combustion of the engine becomes, and for example, the forced vibration by the engine on the vehicle body (NV) tends to increase. Therefore, the amount of retard during catalyst warm-up is determined in advance in consideration of, for example, the forced vibration by the engine on the vehicle body (NV) that is allowed. "NV" is a general term for noise and vibration generated in the vehicle, and represents at least one of noise and vibration in the vehicle. Here, the damper has a function of attenuating the force transmitted to the power transmission system. There is room for improvement from the viewpoint of achieving both promotion of catalyst warm-up and suppression of NV.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a control device for a hybrid vehicle capable of achieving both promotion of catalyst warm-up and suppression of NV.

Means for Solving the Problems

[0006] The gist of the first invention is a control device for a hybrid vehicle including: (a) an engine, (b) an electric motor connected to be power-transmittable in a power transmission path between the engine and drive wheels, and (c) a damper provided between the engine and the electric motor in the power transmission path, the control device including: measuring a torsional angle of the damper by applying torque to the damper by the electric motor in a state where the engine is stopped to obtain a hysteresis torque that is a difference in torque input to the damper between when the torsional angle increases and when it decreases; and when the hysteresis torque is large, setting a larger amount of retard of the ignition timing of the engine during warm-up of a catalyst provided in an exhaust pipe of the engine than when the hysteresis torque is small.

Effects of the Invention

[0007] According to the first invention, when the hysteresis torque obtained in the engine stopped state is large, the retard angle amount of the engine ignition timing during catalyst warm-up is set larger than when it is small. Therefore, the larger the hysteresis torque, the easier it is to warm up the catalyst. When the retard angle amount of the ignition timing is set large and the NV forcing force by the engine is increased, the forcing force transmitted to the power transmission system by the large hysteresis torque is easily attenuated, so the NV is easily suppressed. Therefore, it is possible to achieve both promotion of catalyst warm-up and suppression of NV.

Brief Description of Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Examples

[0010] FIG. 1 is a diagram for explaining the schematic configuration of a vehicle 10 to which the present invention is applied, and is also a diagram for explaining the main part of control functions for various controls in the vehicle 10. The vehicle 10 is a hybrid vehicle including an engine 12, a first electric motor MG1, and a second electric motor MG2 that function as power sources. In the power transmission path PT between the engine 12 and the drive wheels 14, a damper 16, a differential mechanism 18, an output gear 20, a large-diameter gear 22, an engagement clutch 24, a small-diameter gear 26, a differential gear 28, and a pair of left and right drive shafts 30 are connected in order from the engine 12 side. The vehicle 10 includes an engine control device 50 including an ignition device and the like, an inverter 52, a catalyst 54 provided in an exhaust pipe 12b of the engine 12, and an electronic control device 70 and the like.

[0011] The engine 12 is a known internal combustion engine. The engine 12 has its engine torque Te, which is the torque of the engine 12, controlled by the engine control device 50 being controlled by the electronic control device 70.

[0012] The first electric motor MG1 and the second electric motor MG2 are rotary electric machines having functions as, for example, an engine and a generator, and are so-called motor generators. The first electric motor MG1 and the second electric motor MG2 are each connected to a battery (not shown) via the inverter 52. The first electric motor MG1 and the second electric motor MG2 have their MG1 torque Tmg1, which is the torque [Nm] of the first electric motor MG1, and MG2 torque Tmg2, which is the torque of the second electric motor MG2, respectively controlled by the inverter 52 being controlled by the electronic control device 70.

[0013] The damper 16 is a device that absorbs torque fluctuations of the engine 12. The damper 16 includes a first rotating element 16a connected to the crankshaft 12a of the engine 12, and a second rotating element 16b connected to the differential mechanism 18 via the input shaft 32. That is, the damper 16 is provided between the engine 12 and the first electric motor MG1 in the power transmission path PT. Between the first rotating element 16a and the second rotating element 16b, for example, a plurality of types of springs 16c and a friction mechanism 16d are interposed. The stiffness value (spring constant) corresponding to the change in the input torque Tin, which is the torque input to the damper 16 with respect to the change in the twist angle φ [rad] of the damper 16, is changed stepwise, and a predetermined hysteresis (also referred to as a history phenomenon) is imparted to the input torque Tin when the twist angle φ increases and decreases.

[0014] The differential mechanism 18 is, for example, a single pinion type planetary gear device, and the first electric motor MG1, the input shaft 32, and the output gear 20 are connected to the sun gear S, the carrier CA, and the ring gear R, respectively. The first electric motor MG1 is connected to the differential mechanism 18 so as to be capable of power transmission, and is an electric motor connected to the power transmission path PT so as to be capable of power transmission.

[0015] The large-diameter gear 22 meshes with the output gear 20, which is the output rotating member of the differential mechanism 18, and the second output gear 34, which is the output rotating member of the second electric motor MG2, respectively. Between the large-diameter gear 22 and the small-diameter gear 26, an engagement clutch 24 capable of connecting and disconnecting the power transmission therebetween is provided. The small-diameter gear 26 meshes with the differential ring gear 28a of the differential gear 28.

[0016] The vehicle 10 includes a parking gear 36. The parking gear 36 is connected to the drive wheels 14 via the small-diameter gear 26 or the like and rotates together with the drive wheels 14. The parking gear 36 is fixed (locked) so as not to rotate by a known parking lock mechanism (not shown).

[0017] The vehicle 10 is provided with an engagement brake 38. The crankshaft 12a is connected to a housing 40, which is a non-rotating member, via the engagement brake 38. The crankshaft 12a is locked so as not to rotate when the engagement brake 38 is engaged.

[0018] The vehicle 10 can selectively switch each shift range among a "P range (= parking range)", an "R range (= reverse driving range)", an "N range (= neutral range)", and a "D range (= forward driving range)" by operating a shift operating device (not shown), for example.

[0019] The electronic control unit 70 is a controller including a control device that controls each part in the vehicle 10, and includes a so-called microcomputer that performs signal processing according to a program stored in a ROM in advance while a CPU utilizes a temporary storage function of a RAM.

[0020] Various signals (for example, vehicle speed V [km / h], torsional angle φ representing the rotational position of the input shaft 32, engine rotational speed Ne [rpm] which is the rotational speed of the engine 12, catalyst temperature THc which is the temperature of the catalyst 54, etc.) based on detection values by various sensors (for example, vehicle speed sensor 60, input shaft rotation sensor 62, engine rotational speed sensor 64, catalyst temperature sensor 66, etc.) provided in the vehicle 10 are input to the electronic control unit 70, respectively. Various command signals (for example, engine control signal Se for controlling the engine 12, motor control signal Smg for controlling each of the first motor MG1 and the second motor MG2, etc.) are output from the electronic control unit 70 to each device (for example, engine control unit 50, inverter 52, etc.) provided in the vehicle 10, respectively.

[0021] The electronic control unit 70 functionally includes a characteristic measurement unit 72 and a warm-up control unit 74.

[0022] The characteristic measurement unit 72 determines whether the vehicle state allows measurement of the damper characteristics, which are the characteristics of the damper 16. A vehicle state that allows measurement of the damper characteristics is, for example, a state where the vehicle speed V is zero, the shift range is the P range, and the engine 12 is in a stopped state, and the operation of the engine 12 is not required. The measurement timing can be in various modes, such as during vehicle inspection, for each predetermined driving distance or driving time.

[0023] When the characteristic measurement unit 72 determines that the vehicle state allows measurement of the damper characteristics, it measures the damper characteristics. For example, the characteristic measurement unit 72 engages the meshing brake 38 to lock the crankshaft 12a against rotation, engages the meshing clutch 24, and controls the first motor MG1 to apply torque to the damper 16, and measures the torsional angle φ with an input shaft rotation sensor 62 such as a resolver. The MG1 torque Tmg1 applied to the damper 16 during the measurement of the torsional angle φ corresponds to the input torque Tin. Since a differential mechanism 18 is provided between the first motor MG1 and the damper 16, the magnitudes of the MG1 torque Tmg1 and the input torque Tin, which is the torque on the input shaft 32, differ by the speed ratio of the differential mechanism 18, but for convenience, they are treated as the same.

[0024] The characteristic measurement unit 72 obtains the relationship between the torsional angle φ and the input torque Tin as the damper characteristics, and obtains the hysteresis torque Thys [Nm] based on that relationship. The hysteresis torque Thys is the difference in the input torque Tin between when the torsional angle φ increases and when it decreases (see "measurement results" in FIG. 3 described later). In this way, the characteristic measurement unit 72 obtains the hysteresis torque Thys by applying torque to the damper 16 with the first motor MG1 and measuring the torsional angle φ of the damper 16 in a state where the engine 12 is rotationally stopped.

[0025] The warm-up control unit 74 controls the engine 12 to warm up the catalyst 54. For example, when the catalyst temperature THc is less than the predetermined temperature THcf, the warm-up control unit 74 controls the engine 12 to retard the ignition timing by a predetermined retard angle amount θf. The predetermined temperature THcf is a predetermined threshold value at which the warm-up of the catalyst 54 is required.

[0026] The ignition retard amount θ, which is the retard amount of the ignition timing during warm-up of the catalyst 54, is the amount [deg] of retard with respect to the ignition timing during normal operation when the catalyst 54 is not being warmed up, that is, during normal operation when the warm-up of the catalyst 54 is completed. The larger the ignition retard amount θ, the more the warm-up of the catalyst 54 is promoted, but the combustion of the engine 12 becomes unstable, and the NV force by the engine 12 is likely to be increased.

[0027] In the power transmission path PT between the engine 12 and the drive wheels 14 and in the power transmission path between the second electric motor MG2 and the drive wheels 14, there is play, that is, backlash, in the meshing portion between the gears that mesh with each other. The above NV is, for example, a rattling noise (= play rattling noise) called a gear rattle sound that occurs when the tooth surfaces collide and separate from each other repeatedly and strike each other when the explosion variation of the engine torque Te is transmitted to the meshing portion where the force pressing the tooth surfaces against each other is weakened when the MG2 torque Tmg2 is zero or near zero. Or, the above NV is, for example, a gear rattle sound generated by the amplification of the variation due to the drive torsional system resonance using the explosion variation as a forcing force when the explosion variation of the engine 12 stronger than the force pressing the tooth surfaces against each other is transmitted in the meshing portion between the gears in the power transmission path PT. Or, the above NV is, for example, a booming sound generated inside the vehicle when the body vibrates when the amplified explosion variation is transmitted to the suspension via the drive shaft 30 or the like when the explosion variation of the engine 12 becomes a forcing force and the vibration is amplified by the resonance of the power transmission path PT occurring at a specific engine rotational speed Ne.

[0028] The predetermined retard amount θf during warm-up of the catalyst 54 is determined in advance, for example, in consideration of the forced force of NV by the engine 12 for which NV is permitted. That is, the magnitude of the predetermined retard amount θf is restricted so that NV is at an acceptable level. On the other hand, the damper 16 has a function of attenuating the forced force of the engine 12 transmitted to the power transmission path PT. Therefore, the predetermined retard amount θf uniformly set at the retard amount limit value θlim at which the ignition retard amount θ is restricted in consideration only of the forced force of NV by the engine 12 is not necessarily an appropriate value.

[0029] The absolute value of the forced force of NV (the same applies to torque) by the engine 12 is much larger than the hysteresis torque Thys generated by frictional force. The larger the hysteresis torque Thys, the more easily the forced force of NV is attenuated. Therefore, the forced force of NV transmitted to the power transmission path PT is reduced, and NV is more easily suppressed.

[0030] For example, as shown in Fig. 2(a), as the ignition retard angle θ increases, the force of the rattle noise transmitted to the power transmission path PT increases. On the other hand, as the hysteresis torque Thys increases, the force of the rattle noise transmitted to the power transmission path PT decreases, and the rattle noise decreases. Therefore, the ignition retard angle θ at which the rattle noise is below the allowable force increases as the hysteresis torque Thys increases. That is, the maximum ignition retard angle θmax that can be set for each hysteresis torque Thys increases as the hysteresis torque Thys increases (see θ1, θ2, and θ3 in the figure). Increasing the maximum ignition retard angle θmax corresponds to increasing the relaxation margin of the retard angle limit value θlim. Therefore, as shown in Fig. 2(b), the relationship between the hysteresis torque Thys and the relaxation margin of the retard angle limit value θlim is predetermined. In Fig. 2(b), the relaxation margin of the retard angle limit value θlim is set to a larger value as the hysteresis torque Thys increases. The relaxation margin of the retard angle limit value θlim corresponds to, for example, the looseness of the retard angle limit and also corresponds to the magnitude of the ignition retard angle θ. Also, the relaxation margin of the retard angle limit value θlim corresponds to the engine control correction amount Δθ for correcting so as to increase a predetermined retard angle θf with respect to the retard angle limit value θlim. That is, the engine control correction amount Δθ is set to a larger value as the hysteresis torque Thys increases (see the "control correction amount map" in Fig. 3 described later).

[0031] Accordingly, if the hysteresis torque Thys is large, the retard angle limit value θlim is relaxed, so that the relaxation of the NV countermeasure can be performed and the warm-up of the catalyst 54 can be promoted. In this way, when the hysteresis torque Thys is large, the warm-up control unit 74 sets a larger ignition retard angle θ of the engine 12 during the warm-up of the catalyst 54 than when it is small.

[0032] Fig. 3 is a flowchart for explaining the main part of the control operation of the electronic control device 70, and is a flowchart for explaining the control operation for achieving both the promotion of the warm-up of the catalyst 54 and the suppression of NV, and is repeatedly executed, for example.

[0033] In FIG. 3, first, in step S10 corresponding to the function of the characteristic measurement unit 72 (hereinafter, steps are omitted), it is determined whether the vehicle speed V is zero. If the determination in this S10 is affirmative, then in S20 corresponding to the function of the characteristic measurement unit 72, it is determined whether the shift range is the P range. The P range is a shift range in which the parking gear 36 is locked by a parking lock mechanism (not shown). If the determination in this S20 is affirmative, then in S30 corresponding to the function of the characteristic measurement unit 72, it is determined whether the engine 12 is in a stopped state, that is, whether the engine rotational speed Ne is zero. If the determination in this S30 is affirmative, then in S40 corresponding to the function of the characteristic measurement unit 72, it is determined whether the operation of the engine 12 is required. A state where the operation of the engine 12 is required is, for example, a state where warm-up of the catalyst 54 is required, a state where charging of a battery (not shown) is required, and the like. If the determination in this S40 is negative, then in S50 corresponding to the function of the characteristic measurement unit 72, measurement (start) of the damper characteristic is carried out. On the other hand, if any of the determinations in the above S10, the above S20, and the above S30 is negative, or if the determination in the above S40 is affirmative, then the process returns to the above S10. Next to the above S50, in S60 corresponding to the function of the characteristic measurement unit 72, it is determined whether the shift range is other than the P range, or whether the vehicle speed V is other than zero, or whether the operation of the engine 12 is required. If the determination in this S60 is affirmative, then in S70 corresponding to the function of the characteristic measurement unit 72, measurement of the damper characteristic is interrupted. If the determination in the above S60 is negative, then in S80 corresponding to the function of the characteristic measurement unit 72, it is determined whether the measurement of the damper characteristic has ended. Next to the above S70, or if the determination in the above S80 is negative, then the process returns to the above S10. If the determination in the above S80 is affirmative, then in S90 corresponding to the functions of the characteristic measurement unit 72 and the warm-up control unit 74, the hysteresis torque Thys is obtained based on the measurement result of the damper characteristic (refer to "measurement result" in the figure).Also, using the relationship between a predetermined hysteresis torque Thys and an engine control correction amount Δθ (refer to the "control correction amount map" in the figure), an engine control correction amount Δθ corresponding to the hysteresis torque Thys is calculated (selected), and the program for controlling the engine 12 regarding the warm-up of the catalyst 54 is rewritten. For example, a predetermined retard angle amount θf is rewritten.

[0034] As described above, according to this embodiment, when the hysteresis torque Thys is large, the ignition retard angle amount θ during the warm-up of the catalyst 54 is set larger than when it is small. Therefore, the larger the hysteresis torque Thys, the easier it is to warm up the catalyst 54. When the ignition retard angle amount θ is set large and the forced force of NV by the engine 12 is increased, the forced force transmitted to the power transmission path PT by the large hysteresis torque Thys is easily attenuated, so NV is easily suppressed. Thus, it is possible to achieve both the promotion of the warm-up of the catalyst 54 and the suppression of NV. Also, it is possible to cope with individual differences and aging changes of the damper 16.

[0035] The embodiments of the present invention have been described above, but the present invention is also applicable in other aspects. For example, the present invention can be applied to a hybrid vehicle equipped with a damper provided between an engine and an electric motor. Note that the above is merely one embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

Explanation of reference numerals

[0036] 10: Vehicle (hybrid vehicle) 12: Engine 12b: Exhaust pipe 14: Driving wheel 16: Damper 54: Catalyst 70: Electronic control unit (control unit) MG1: First electric motor (electric motor) PT: Power transmission path

Claims

【Claim 1】 A control device for a hybrid vehicle, comprising: an engine; an electric motor connected to be capable of transmitting power in a power transmission path between the engine and drive wheels; and a damper provided between the engine and the electric motor in the power transmission path, wherein when the engine is in a rotation stop state, torque is applied to the damper by the electric motor to measure a torsional angle of the damper, and a hysteresis torque, which is a difference in torque input to the damper between when the torsional angle increases and when it decreases, is obtained; when the hysteresis torque is large, a retard angle amount of an ignition timing of the engine during warm-up of a catalyst provided in an exhaust pipe of the engine is set larger than when the hysteresis torque is small. A control device for a hybrid vehicle characterized by this.

Images